- Email: [email protected]
Aerobic fitness and field test performance in elite Spanish soccer referees of different ages
Journal of Science and Medicine in Sport (2007) 10, 382—389
Aerobic fitness and field test performance in elite Spanish soccer referees of different ages Jos´ e Antonio Casajus a, Carlo Castagna b,∗ a
Faculty of Health and Sport, University of Zaragoza, Spain School of Sport and Exercise Sciences, Faculty of Medicine and Surgery, University of Rome Tor Vergata, Rome, Italy
b
Received 2 March 2006 ; received in revised form 28 August 2006; accepted 31 August 2006 KEYWORDS Ageing; Muscle performance; Training; Endurance; Maximal oxygen uptake; Sprinting
Summary The major aim of this study was to examine the physical fitness of elite Spanish soccer referees in relation to their age. A secondary aim was to assess the population criterion validity of the 12 min running test (12 MRT) against aerobic-fitness laboratory tests. Participants were 45 soccer referees (age 35.5 ± 4.4 years, height 178.3 ± 5.0 cm, body mass 75.1 ± 6.6 kg, body fat 11.3 ± 2.15%, VO2max 54.9 ± 3.9 ml kg−1 min−1 ) who were enrolled in the Referees Technical Committee of the Royal Spanish Soccer Federation. They were divided into three age groups: young (Y, 27—32 years, n = 15), average (A, 33—38 years, n = 17) and old (O, 39—45 years, n = 13). No age-related effects were observed for VO2max , 12 MRT or 200 m sprint performance in either the pooled or grouped data. However, age-related performance decrements were observed for 50 m sprint performance and the ventilatory threshold (VT) running speed. Twelve MRT performance was moderately related to VO2max (r = 0.46, P = 0.002), VT (km h−1 ) (r = 0.49, P < 0.001), and peak treadmill velocity (PTV) (r = 0.60, P < 0.001). The results showed that older elite-level referees may be able to limit the expected age-related performance decrements in both aerobic and anaerobic performance usually reported for sedentary people. Additionally, these results show that older referees are able to reach physical fitness levels that have been suggested to be appropriate for coping with match demands. © 2006 Published by Elsevier Ltd on behalf of Sports Medicine Australia.
Introduction Recent studies have shown that soccer refereeing is a physically challenging exercise mainly stressing aerobic metabolism.1 During a competitive match, ∗ Corresponding author. Tel.: +39 071 28 66 532(R); fax: +39 071 28 66 478. E-mail address: [email protected] (C. Castagna).
elite-level soccer referees can cover a mean distance of 11.5 km (range 9—14 km),2—6 attaining 85—95% of their estimated and individual maximal heart rate.2,4—7 It has also been reported that elite-level soccer referees work at 68% of their VO2max when officiating friendly matches. These physiological stresses imposed on the elite soccer referee are similar to that endured by mid-field soccer players.3,8 However, despite the similarities
1440-2440/$ — see front matter © 2006 Published by Elsevier Ltd on behalf of Sports Medicine Australia.
doi:10.1016/j.jsams.2006.08.004
Fitness performance in soccer referees in general physiological demands, there are several aspects of referees’ performance that distinguish their match requirements from that of the players. For instance, officials are not directly involved with the ball and cannot be substituted during the match. Professional soccer referees are usually older than professional soccer players. For example, the mean age of referees officiating at the Euro 2000 Championship was reported to be 40.2 ± 3.9 years9 compared to the mean age of the players competing in the Spanish championship: 24.5 ± 2.5 years [http://www.fifaworldcup.yahoo.com/; accessed 25th July 2002]. Further analysis of the ages of the world’s best referees who officiated the quarter-finals at the 2002 World Cup shows that the mean age was 41 ± 4 years (n = 8, [http://www.fifaworldcup.yahoo.com/; accessed 25th July 2002]). Paradoxically, these data show that elite soccer referees officiate at the highest level at an average age when most soccer players have retired from competition (i.e., >40 years). The difference in the mean age of players and referees may exist because of the time that it takes to gain the competitive match experience. Such experience is considered a fundamental prerequisite to officiate at the elite level by the refereeing governing bodies (Federation Internationale de Football Association, FIFA, and Union Europenne de Football Association, UEFA).10 These data suggest that referees are selected to officiate at the highest level when they reach ages where physiological functioning is not optimal.11—13 For example, maximal oxygen uptake (VO2max ) has been reported to decrease by ∼10% per decade after the age of 25 years in healthy sedentary men.14 Moreover, age-related decrements have been reported in respiratory capacity and submaximal exercise performance.15 Training status seems to have a significant effect on the agerelated decrements in aerobic fitness, by reducing the rate of decline in VO2max by ∼5% per decade.16 Recently, Mattern et al. reported a 3.3% decrease in sub-maximal aerobic performance per decade in well-trained subjects (cycling and triathlon).11 Since aerobic fitness has been shown to be related to physical performance,17—19 we suggest that this age-related decline in aerobic fitness may affect soccer referee match physical performance. At higher competition levels of soccer, the speed of the match play is higher,1 which may increase the physiological/running demands of refereeing. As a consequence of the increased physical demands at the higher levels of soccer competition,20 there is a clear need for an appropriate fitness level of the match referees. Accordingly, the governing bodies
383 of elite-level referees now implement regular fitness testing17 and supervised training sessions21 in an attempt to control and regulate the physical fitness of referees. For example, both FIFA and UEFA now systematically assess the fitness level of their affiliated referees with a battery of field tests consisting of 50 and 200 m sprints and 12 min running (12 MRT) for distance.10 Since FIFA and UEFA have adopted these tests, many other national referees’ associations have also used this test battery as evaluation tool for fitness and physical performance.17,22 However, although the 50, 200 m and 12 MRT have been widely used by national referees’ associations around the world, only few studies have evaluated the relevance of these tests to match performance.5,17 Additionally, to our knowledge, no scientific studies have examined the criterion validity of these tests for referees. Therefore, the first aim of this study was to investigate possible age-related difference in physiological and field tests performance in elite soccer referees of different officiating experience. Furthermore, since the 12 MRT10 is the most popular field test for aerobic fitness in soccer refereeing, the second aim of this study was to determine the criterion validity of 12 MRT in a group of highly competitive officials. The research hypothesis was that physical and physiological performance would be decreased with age in elite soccer referees.
Material Subjects The research examined the performance and physiological responses of 45 elite referees enrolled in the Referees Technical Committee of the Royal Spanish Soccer Federation. All subjects (n = 45, see Table 1) were experienced (>10 years professional level) elite-level referees from the Spanish Soccer Referees Association (CTA). Ten of the referees who participated in this study had previously officiated international matches. All referees were in good health and had taken part in the supervised physical training program that we had implemented.
Methods Experimental design Prior to exercise testing each referee was required to undertake a medical examination, which
384 Table 1
J.A. Casajus, C. Castagna Anthropometrical characteristics of entire group (n = 45) and Y, A and O groups
Variables
Group All [n = 45]
Age (year) Height (cm) Body Mass (kg) Skinfolds sum (mm) % Fat
35.5 178.3 75.1 83.2 11.3
± ± ± ± ±
4.4 5.0 6.6 20.5 2.15
Young [n = 15] 30.4 178.7 73.4 80.8 11.1
± ± ± ± ±
AO
1.5 5.4 6.1 11.3 0.56
Average [n = 17] 35.8 179.4 77.3 81 11.1
± ± ± ± ±
YO
1.2 4.8 6.9 14.1 0.53
Old [n = 13] 40.4 176.4 74.3 88.9 11.9
± ± ± ± ±
2.5YA 4.5 6.2 32.8 0.60
A Significantly
different from Average group P < 0.05; Y significantly different from Young group P < 0.05; O significantly different from Old group P < 0.05.
included blood screening, electro-cardiogram at rest, basal lung function tests and blood pressure measurements. In addition, all referees provided a written informed consent after they were given a detailed explanation as to the nature of the research. All tests were conducted during the preseason of the 2001—2002 Spanish championship (in August, after 4 weeks of training). The referees were all familiar with the testing procedures undertaken in this study. Specifically, all referees undertook the field test and laboratory test protocols in the 6 months prior to the study. The referees used in this study were eligible to officiate in the professional Spanish championships (Liga 1a Division and Liga 2a Division, first and second soccer division, respectively) and were members of the CTA. In Spain, only 45 referees are selected to officiate in the Liga 1a and 2a Championships each year. These referees are selected on the basis of their refereeing ability and physical fitness. Furthermore, referees who are older than 45 are not eligible to be selected to officiate in these championships. Due to the rigorous selection process and to the high level of play taking place in the Liga 1a and 2a championships, the referees in this study were considered to be representative of elite-level soccer referees. In order to test the likelihood of age-related variations in fitness performance, the referees were grouped into three age-group categories: young (Y, 27—32 years n = 15), average (A, 33—38 years, n = 17) and old (O, 39—45 years, n = 13).23 The selection for the grouping categories was based on the methods proposed by Castagna et al.,23 addressing similar populations of elite-level soccer referees. The Y, A and O groups were matched for both training intensity and volume performed during the three months preceding the commencement of this cross-sectional study.23 The age range considered for the O group was chosen, because the CTA considers 39 as the higher age limit to get access or aspire to elite-level soccer refereeing. The Y group was formed as representative
of the third decade of life considered as the age when morphological and physiological declines in skeletal muscle performance begin.11 These three groups were then tested using the field fitness test battery in use by UEFA at the time of this investigation10 (i.e., 50, 200 and 12 min run test) and with laboratory-based tests for aerobic fitness (i.e., treadmill running-test for VO2max and ventilatory threshold (VT) assessment). These measures of aerobic fitness were taken because recent studies have clearly shown that speed at selected lactate thresholds and VO2max are associated with physical match-performance in elite-level soccer referees.17,18 The Ethics Committee of the University of Zaragoza (Spain) and the CTA approved the research design.
Laboratory testing Aerobic fitness tests were performed at the same time of the day (09:00—14:00 h) under similar environmental conditions (temperature ∼20 ◦ C; relative humidity 45—55%; barometric pressure ∼720 mmHg). All subjects refrained from performing physical activity during the 24 h period before each test. Each subject performed an incremental exercise test to exhaustion on a motorised treadmill (Jaeger Laufergotest, Germany) for determination of ventilatory threshold (VT),24 maximal ventilation (VEmax ) and maximal oxygen uptake (VO2max ). Attainment of VO2max was considered when at least two of the following criteria were satisfied: (1) plateau in VO2 despite an increase in exercise intensity; (2) HR greater than 90% of the age-predicted maximal value (220-age); (3) a respiratory exchange ratio (RER) greater than 1.15. Following a 5 min warm-up, the incremental treadmill protocol commenced at a workload of 8 km h−1 and a 1% grade. The treadmill speed
Fitness performance in soccer referees
385
was increased by 1 km h−1 every minute until volitional exhaustion. The heart rate was monitored electrocardiographically and displayed simultaneously on the screen of the oscilloscope (Hellige, Servimed, Germany). Gas exchange measurements were made breath-by-breath during the test and for 3 min during the recovery (Medical GraphicsCardiopulmonary Exercise System CPX, USA). The speed at exhaustion was assumed as peak treadmill velocity (PTV) according to Noakes.25
referees throughout the test at regular intervals (i.e., every 2 min). Distance covered was assessed making subjects remain on the athletic-track spot reached at end of the 12 min run and counting laps performed plus possible extra space (rounded to the nearest metre using a measurement wheel). Experienced and qualified fitness trainers implemented all tests on behalf of the CTA.
Anthropometrical measurements
Data are presented as mean and standard deviation. The Kolmogorov—Smirnov test was applied to ensure a normal distribution of parametric data. One-way analysis of variance (ANOVA) with a Tukey HSD post hoc comparison was used to determine significant differences between the young, average and old groups of referees. The relationships between variables of interest were detected using Pearson’s correlation coefficient (r) and estimations were performed using bivariate regression equations. Significance was set for the calculations at 5% (P ≤ 0.05). All calculations were performed using Statistica software package (Version 6.01 StatSoft, Tulsa, USA).
Standard anthropometrical variables (stature, body mass, biceps-epicondylar humerus and femur width, arm flexed and extended and calf girths, and triceps, subscapular, supraspinal, abdominal, front thigh and medial calf skinfolds) were obtained on all subjects by a trained anthropometrist, following methods suggested by the International Society for the Advancement of Kinanthropometry.26 Anthropometric instruments used in this study included a stadiometer, scale, small sliding calliper (Rabonne Chesterman, Silverflex, UK), anthropometric tape (GPM Siber-Hegner Maschinen, Switzerland) and skinfold calliper (Holtain LTD, Crymych, UK). Percentage of body fat was estimated according to Carter’s equation.27 Sum of six skinfolds was also used as index of adiposity.
Field tests Field tests were performed on a tartan athletic track 5 days after the cardiorespiratory test. Each testing session was performed with well-rested (moderate exercise during the 24—48 h preceding testing, i.e., 20—30 min running at 70% of individual maximal heart rate) subjects and all test bouts were completed at the period of the day when most Spanish matches are played (16:00—18:00 h). Furthermore, the environmental conditions during testing sessions were similar to those experienced by referees during matches. The field tests were conducted in the following order: 50, 200 m and 12 MRT. Ten minutes of active rest (walking-jogging) was provided between the 50 m and the 200 m test and 15 min of rest was allowed between the 200 m sprint and the start of the 12 MRT. The 50 and 200 m times were assessed with the aid of photo-cells (Racetime 2 Kit SF, Bolzan, Italy), whereas 12 MRT times were clocked with an electronic stopwatch (Casio HS 30 W, Tokyo, Japan). The 12 MRT consisted in covering as much as distance as possible running for 12 min on a tartan athletic-track. Only 10 referees at a time were tested and time passage feedback was provided to
Statistical analyses
Results The anthropometrical and physiological characteristics of the participants to this study are shown in Tables 1 and 2, respectively. The mean age of each of the groups was significantly different (P < 0.001). No significant group differences were observed for height, body mass, skinfolds sum and percentage of body fat (% Fat) (P > 0.05). Referees in the O group were significantly slower in the 50 m sprint compared to Y group (6.90 ± 0.31 and 6.62 ± 0.18 s, respectively, P < 0.001). No significant age effects were evident for 200 and 12 MRT performances (P > 0.05). Heart rate at VT (VT% HRmax ) and relative PTV at VT (VT% PTV) of the Y group was significantly different from that of the O group (P < 0.01). Speed at VT was significantly higher in the A group compared to the O group (15.5 ± .9 and 14.5 ± 1.4 s, respectively, P < 0.001). Both relative and absolute VO2max was not significantly different across the age groups (P > 0.05). Twelve MRT performance was moderately related to VO2max (r = 0.46, P = 0.002, see Fig. 1), VT (km h−1 ) (r = 0.49, P < 0.001) and PTV (r = 0.60, P < 0.001, see Fig. 2). The 200 m sprint performance was significantly correlated to %PTV at VT (r = −0.51, P < 0.001). The 50 m performance was significantly related to 200 m performance (r = 0.79, P = 0.001).
386 Table 2
J.A. Casajus, C. Castagna Physiological and fitness tests results of the entire group (n = 45) and Y, A and O groups
Variables
Group All [n = 45] −1
VO2 (L min ) VO2 (ml kg−1 min−1 ) VEmax (l min−1 ) VT (km h−1 ) PTV (km h−1 ) HRmax (beat min−1 ) VT (ml kg−1 min−1 ) VT %VO2max VT% HRmax VT% PTV 50 m (s) 200 m (s) 12 MRT (m) O Significantly
4.1 54.9 137 15.1 17.9 182 46.3 84.4 92.5 84.29 6.76 28.95 2984
± ± ± ± ± ± ± ± ± ± ± ± ±
0.4 3.9 15 1.1 0.9 9 3.9 5.4 3.0 4.29 0.25 1.28 125
Young [n = 15] 4.1 55.3 139 15.2 17.8 185 47.3 85.7 94.1 85.7 6.62 28.43 2986
± ± ± ± ± ± ± ± ± ± ± ± ±
0.4 4.5 15 1.0 1.0 7 3.4 5.8 2.0O 3.7O 0.18O 1.02 122
Average [n = 17] 4.2 55.3 137 15.5 18.2 181 46.6 84.3 92.3 85.2 6.78 29.02 2978
± ± ± ± ± ± ± ± ± ± ± ± ±
0.3 3.3 17 .9O 0.8 10 3.1 3.7 2.5 2.9O 0.20 1.02 97
Old [n = 13] 4.0 53.8 134 14.5 17.8 180 44.7 83.0 91.0 81.6 6.90 29.47 2988
± ± ± ± ± ± ± ± ± ± ± ± ±
0.4 3.8 15 1.4 1.0 9 4.9 6.7 3.6 5.4 0.31 1.60 165
different from Older group; P < 0.05.
Discussion
Figure 1 Relationship between VO2max (ml kg−1 min−1 ) and 12 MRT (r = 0.46, P = 0.002).
Figure 2 Relationship between VO2max (ml kg−1 min−1 ) and PTV (r = 0.60, P < 0.001).
The results of this study showed that there were age-related differences in selected components of physical fitness in this group of elite-level soccer referees. Specifically, both short maximal anaerobic sprinting (50 m sprint) and sub-maximal (VT) aerobic measures were significantly better in younger referees compared to their older counterparts. However, both VO2max and 12 MRT, the variables that have previously been shown to strongly relate to match running performance,17,19 showed no significant difference among the age groups. These findings suggest that older referees possess aerobic performances similar to those showed by their younger colleagues. In this study, we found no age-related effects on VO2max . The present results are in contrast to previous research that has reported age-related decrements in VO2max of 5—15% per decade after the age of 25 years.12 The age-related decrement in VO2max has been mainly attributed to decreased cardiac output12,28 and decreased heart contractility.16,29 However, we did not observe any changes in HRmax between the age groups in this study. Similarly, there were no differences in any of the anthropometrical measures between the young, average or older referees in this study. It is possible that the maintenance of appropriate body composition may have also contributed to the maintenance of aerobic fitness in the older referees.14 The small but significant correlation between body fat percentage and relative VO2max (r = −0.34, P = 0.02) supports this suggestion. It is possible that the history of regular high-intensity training among this group of older elite-level referees may have prevented or
Fitness performance in soccer referees diminished the anticipated decline in VO2max that is common in a non-elite population.30 A lower sub-maximal exercise performance was observed in the older referees compared to their younger counterparts. Specifically, the O group showed a significantly lower running velocity (km h−1 ) and %PTV at VT compared to the Y group. These results are in contrast to previous research13 that reported neither age-related declines in VO2 nor increments in % of VO2max during sub-maximal aerobic exercise. The decline in sub-maximal exercise performance observed in older referees is in line with that which has been reported in non-professional cyclists.11 Although the mechanisms underlying these age-related changes are not understood, it is possible that an age-related reduction in muscle power was the cause for the reduction in sub-maximal running performance. In fact, several previous studies have shown a strong relationship between neuromuscular efficiency and sub-maximal running performance in active individuals.31—33 In this study, we found that 50 m sprint performance was decreased in the older group of referees. This reduction in neuromuscular power might also explain the reduced sub-maximal running capacity in the older group of referees. Previous studies have suggested that there is a strong relationship between neuromuscular performance and sub-maximal aerobic performance.31—33 In support, we observed a moderate correlation between 50 m performance and VT (km h−1 ) (r = −0.41 P = 0.05) and VT (ml kg−1 min−1 ) (r = −0.55 P < 0.001). Taken collectively, these results might suggest that the reduction in neuromuscular power with ageing is related to the reduced sub-maximal aerobic performance in older referees. However, caution must be taken when interpreting these suggestions as the correlation analysis does not demonstrate a cause—effect relationship. The possible effects of the reduced sprint and sub-maximal aerobic performance on match physical performance are difficult to quantify accurately. In fact, 50 m sprint performance has been previously reported to not be significantly related to match physical performance.17 Conversely, higher speeds at selected lactate threshold have been reported to be related to greater match coverage in elite-level soccer referees.18 As total-match distance has been related to optimal positioning in soccer refereeing,1 higher speed at VT could be of some benefit for older referees.17,19 Bangsbo et al. have recently reported that older top-class referees (age 40—46 years) do not have greater difficulty in keeping up with the game when compared to their younger counterparts (age 29—34 and 35—39
387 years).34 Probably, 12 MRT and VO2max levels similar to those found in the younger counterparts may compensate for the reported under-performance in VT. In this study, there was a moderate relationship between the 12 MRT, VO2max (r = 0.42, P = 0.002) and sub-maximal (VT) aerobic fitness (r = 0.49, P < 0.001). Indeed, the correlation between the 12 MRT and VO2max was lower than the values reported in previous research.23,35 It is possible that the lower correlation between these variables in this study compared to previous research (VO2max standard deviations ±3.9 and 5.91 ml kg−1 min−1 , respectively) is that there is a greater level of homogeneity of the aerobic fitness levels of the referees in this study. 23 In agreement with previous research, 25,36 this study also demonstrated that PTV has a stronger relationship with aerobic-performance than other component of aerobic-fitness measured in this study. In fact, previous studies have shown PTV to be associated with endurance performance over a large range of distances from 1500 m through to the marathon.25,36 The likely explanation for the higher relationship between 12 MRT and PTV found in this study is that PTV may reflect the interaction between an individual’s VO2max , exercise economy, anaerobic capacity and muscle power and thus better characterising aerobic performance.25,31—33,36 This test may be a useful measure for assessing changes in performance and fitness changes in elite referees. Furthermore, since the 12 MRT is usually conducted in the outdoors, performance may be affected by environment changes and therefore may not be sufficiently reliable or sensitive to small changes in performance. The VO2max levels (54.9 ± 3.9 ml kg−1 min−1 ) of the elite Spanish soccer referees in this study are considerably higher than those previously reported for competitive level referees of other countries.1 For example, the mean VO2max values of 49.30 ± 8.0 and 50.9 ± 5.7 ml kg−1 min−1 have been reported in elite-level Italian referees19 and English Premier League referees,7 respectively. Similar values were reported for Danish top-class referees with the mean VO2max of 46.3 ml kg−1 min−1 (range: 40.9—56 ml kg−1 min−1 ).5 However, the VO2max levels measured in this study are approximately 16% lower than those reported by Casajus37 for the same period of the season in Spanish elite-level soccer players (65.5 ± 8.0 ml kg−1 min−1 ) competing in the same League. The reasons for the higher VO2max levels found for this group of officials are difficult to determine. It is possible that the higher VO2max levels observed in this study may be due to the supervised fitness training performed throughout
388 the competitive year,28,38 daily lifestyle39 and/or genetic factors.12 The results of this study showed that older elitelevel referees may be able to limit the expected age-related performance decrements in both aerobic and anaerobic performance usually reported for sedentary people. Additionally, they show that older referees are able to maintain physical fitness levels that have been suggested to be appropriate for coping with match demands.17,40
J.A. Casajus, C. Castagna
13.
14.
15.
16.
Practical implications • Training should focus on training maximal aerobic power and aerobic endurance development of elite-level referees of all ages. • Trainers of referees should focus on control of the body mass and composition of older referees. • Training of referees should also include activities that focus on increasing explosivestrength and running speed.
17.
18.
19.
20.
21.
References 22. 1. Stølen T, Chamari K, Castagna C, et al. Physiology of soccer: an update. Sports Med 2005;35(6):501—36. 2. D’Ottavio S, Castagna C. Physiological load imposed on elite soccer referees during actual match play. J Sports Med Phys Fitness 2001;41(1):27—32. 3. D’Ottavio S, Castagna C. Analysis of match activities in elite soccer referees during actual match play. J Strength Cond Res 2001;15(2):167—71. 4. Johnston L, McNaughton L. The physiological requirements of soccer refereeing. Aust J Sci Med Sport 1994;26(3—4):67—72. 5. Krustrup P, Bangsbo J. Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training. J Sports Sci 2001;19:881—91. 6. Catterall C, Reilly T, Atkinson G, et al. Analysis of work rate and heart rates of association football referees. Br J Sports Med 1993;27:153—6. 7. Weston M, Brewer J. A study of the physiological demands of soccer refereeing. J Sports Sci 2002;20:59— 60. 8. Bangsbo J, Norregaard L, Thorso F. Activity profile of competition soccer. Can J Sport Sci 1991;16(2):110—6. 9. Helsen W, Bultynck JB. Physical and perceptual-cognitive demands of top-class refereeing in association football. J Sports Sci 2004;22:179—89. 10. Eissmann HJ, D’Hooghe M. Sports medical examinations. In: The 23rd man: sports medical advice for football referees. Leipzig, Germany: Gers¨ one-Druck; 1996. 11. Mattern CO, Gutilla MJ, Bright DL, et al. Maximal lactate steady state declines during the aging process. J Appl Physiol 2003;95(6):2576—82. 12. Taylor AH, Cable NT, Faulkner G, et al. Physical activity and older adults: a review of health benefits and the effec-
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
tiveness of interventions. J Sports Sci 2004;22(8):703— 25. Wiswell RA, Jaque SV, Marcell TJ, et al. Maximal aerobic power, lactate threshold, and running performance in master athletes. Med Sci Sports Exerc 2000;32(6):1165— 70. Rogers MA, Hagberg JM, Martin WH, et al. Decline in VO2max with ageing in masters athletes and sedentary men. J Appl Physiol 1990;68:2195—9. Coggan AR, Abduljalil AM, Swanson SC, et al. Muscle metabolism during exercise in young and older untrained and endurance-trained men. J Appl Physiol 1993;75:2125—33. Heath GW, Hagberg JM, Ehsani AA, et al. A physiological comparison of young and older endurance athletes. J Appl Physiol 1981;51(3):634—40. Castagna C, Abt G, D’Ottavio S. Relation between fitness tests and match performance in elite Italian soccer referees. J Strength Cond Res 2002;16(2):231—5. Castagna C, Abt G, D’Ottavio S. The relationship between selected blood lactate thresholds and match performance in elite soccer referees. J Strength Cond Res 2002;16(4):623—7. Castagna C, D’Ottavio S. Effect of maximal aerobic power on match performance in elite soccer referees. J Strength Cond Res 2001;15(4):420—5. Williams AM, Lee D, Reilly T. A quantitative analysis of matches played in the 1991—92 and 1997—98 seasons. London: The Football Association; 1999. Weston M, Helsen W, MacMahon C, et al. The impact of specific high-intensity training sessions on football referees’ fitness levels. Am J Sport Med 2004;32(1 Suppl.):54s—61s. Rontoyannis GP, Stalikas A, Sarros G, et al. Medical, morphological and functional aspects of Greek football referees. J Sports Med Phys Fitness 1998;38:208—14. Castagna C, Abt G, D’Ottavio S, et al. Age-related effects on fitness performance in elite-level soccer referees. J Strength Cond Res 2005;19(4):785—90. Beaver WL, Wasserman K, Whipp BJ. A new method for detecting anaerobic threshold by gas exchange. J Appl Physiol 1986;60(6):2020—7. Noakes TD. Implications of exercise testing for prediction of athletic performance: a comtemporary perspective. Med Sci Sports Exerc 1988;20(4):319—30. Eston RG, Reilly T. Kinanthropometry and exercise physiology laboratory manual: tests, procedures and data: anthropometry, vol. 1. London: Routledge; 2001. Carter JEL. Physical structure of olympic athletes. Part I. The Montreal olympic games. Anthropological project. Basel: S. Karger; 1982. Proctor DN, Joyner MJ. Skeletal muscle mass and the reduction of VO2max in trained older subjects. J Appl Physiol 1997;82(5):1411—5. Higginbotham MB, Morris KG, Williams RS, et al. Physiologic basis for the age-related decline in aerobic work capacity. Am J Cardiol 1986;57(15):1374—9. Rognmo Ø, Hetland E, Helgerud J, et al. High intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease. Eur J Cardiovasc Prev Rehabil 2004;11(3):216—22. Paavolainen L, Hakkinen K, Hamalainen I, Nummela A, Rusko H. Explosive-strength training improves 5-km running time by improving running economy and muscle power. J Appl Physiol 1999;86(5):1527—33. Nummela AT, Paavolainen LM, Sharwood KA, et al. Neuromuscular factors determining 5 km running performance
Fitness performance in soccer referees
33.
34.
35. 36.
and running economy in well-trained athletes. Eur J Appl Physiol Occup Physiol 2006;97(1):1—8. Paavolainen LM, Nummela AT, Rusko HK. Neuromuscular characteristics and muscle power as determinants of 5-km running performance. Med Sci Sports Exerc 1999;31(1):124—30. Bangsbo J, Mohr M, Krustrup P. Physical capacity and match performance of top-class referees in relation to age. J Sports Sci 2004;22:524. Cooper KH. A means of assessing maximal oxygen intake. J Am Med Assoc 1968;(203):201—4. Noakes TD, Myburgh KH, Schall R. Peak treadmill running velocity during the VO2max test predicts running performance. J Sports Sci 1990;8(1):35—45.
389 37. Casajus J. Seasonal variation in fitness variables in professional soccer players. J Sports Med Phys Fitness 2001;41:463—9. 38. Lawrenson L, Hoff J, Richardson RS. Aging attenuates vascular and metabolic plasticity but does not limit improvement in muscle VO2max . Am J Physiol Heart Circ Physiol 2004;286(4):1565—72. 39. Aoyagi Y, Katsuta S. Relationship between the starting age of training and physical fitness in old age. Can J Sport Sci 1990;15(1):65—71. 40. Weston M, Bird S, Helsen W, et al. The effect of match standard and referee experience on the objective and subjective match workload of English Premier League referees. J Sci Med Sport 2006;9(3):256—62.
Available online at www.sciencedirect.com
Aerobic fitness and field test performance in elite Spanish soccer referees of different ages Jos´ e Antonio Casajus a, Carlo Castagna b,∗ a
Faculty of Health and Sport, University of Zaragoza, Spain School of Sport and Exercise Sciences, Faculty of Medicine and Surgery, University of Rome Tor Vergata, Rome, Italy
b
Received 2 March 2006 ; received in revised form 28 August 2006; accepted 31 August 2006 KEYWORDS Ageing; Muscle performance; Training; Endurance; Maximal oxygen uptake; Sprinting
Summary The major aim of this study was to examine the physical fitness of elite Spanish soccer referees in relation to their age. A secondary aim was to assess the population criterion validity of the 12 min running test (12 MRT) against aerobic-fitness laboratory tests. Participants were 45 soccer referees (age 35.5 ± 4.4 years, height 178.3 ± 5.0 cm, body mass 75.1 ± 6.6 kg, body fat 11.3 ± 2.15%, VO2max 54.9 ± 3.9 ml kg−1 min−1 ) who were enrolled in the Referees Technical Committee of the Royal Spanish Soccer Federation. They were divided into three age groups: young (Y, 27—32 years, n = 15), average (A, 33—38 years, n = 17) and old (O, 39—45 years, n = 13). No age-related effects were observed for VO2max , 12 MRT or 200 m sprint performance in either the pooled or grouped data. However, age-related performance decrements were observed for 50 m sprint performance and the ventilatory threshold (VT) running speed. Twelve MRT performance was moderately related to VO2max (r = 0.46, P = 0.002), VT (km h−1 ) (r = 0.49, P < 0.001), and peak treadmill velocity (PTV) (r = 0.60, P < 0.001). The results showed that older elite-level referees may be able to limit the expected age-related performance decrements in both aerobic and anaerobic performance usually reported for sedentary people. Additionally, these results show that older referees are able to reach physical fitness levels that have been suggested to be appropriate for coping with match demands. © 2006 Published by Elsevier Ltd on behalf of Sports Medicine Australia.
Introduction Recent studies have shown that soccer refereeing is a physically challenging exercise mainly stressing aerobic metabolism.1 During a competitive match, ∗ Corresponding author. Tel.: +39 071 28 66 532(R); fax: +39 071 28 66 478. E-mail address: [email protected] (C. Castagna).
elite-level soccer referees can cover a mean distance of 11.5 km (range 9—14 km),2—6 attaining 85—95% of their estimated and individual maximal heart rate.2,4—7 It has also been reported that elite-level soccer referees work at 68% of their VO2max when officiating friendly matches. These physiological stresses imposed on the elite soccer referee are similar to that endured by mid-field soccer players.3,8 However, despite the similarities
1440-2440/$ — see front matter © 2006 Published by Elsevier Ltd on behalf of Sports Medicine Australia.
doi:10.1016/j.jsams.2006.08.004
Fitness performance in soccer referees in general physiological demands, there are several aspects of referees’ performance that distinguish their match requirements from that of the players. For instance, officials are not directly involved with the ball and cannot be substituted during the match. Professional soccer referees are usually older than professional soccer players. For example, the mean age of referees officiating at the Euro 2000 Championship was reported to be 40.2 ± 3.9 years9 compared to the mean age of the players competing in the Spanish championship: 24.5 ± 2.5 years [http://www.fifaworldcup.yahoo.com/; accessed 25th July 2002]. Further analysis of the ages of the world’s best referees who officiated the quarter-finals at the 2002 World Cup shows that the mean age was 41 ± 4 years (n = 8, [http://www.fifaworldcup.yahoo.com/; accessed 25th July 2002]). Paradoxically, these data show that elite soccer referees officiate at the highest level at an average age when most soccer players have retired from competition (i.e., >40 years). The difference in the mean age of players and referees may exist because of the time that it takes to gain the competitive match experience. Such experience is considered a fundamental prerequisite to officiate at the elite level by the refereeing governing bodies (Federation Internationale de Football Association, FIFA, and Union Europenne de Football Association, UEFA).10 These data suggest that referees are selected to officiate at the highest level when they reach ages where physiological functioning is not optimal.11—13 For example, maximal oxygen uptake (VO2max ) has been reported to decrease by ∼10% per decade after the age of 25 years in healthy sedentary men.14 Moreover, age-related decrements have been reported in respiratory capacity and submaximal exercise performance.15 Training status seems to have a significant effect on the agerelated decrements in aerobic fitness, by reducing the rate of decline in VO2max by ∼5% per decade.16 Recently, Mattern et al. reported a 3.3% decrease in sub-maximal aerobic performance per decade in well-trained subjects (cycling and triathlon).11 Since aerobic fitness has been shown to be related to physical performance,17—19 we suggest that this age-related decline in aerobic fitness may affect soccer referee match physical performance. At higher competition levels of soccer, the speed of the match play is higher,1 which may increase the physiological/running demands of refereeing. As a consequence of the increased physical demands at the higher levels of soccer competition,20 there is a clear need for an appropriate fitness level of the match referees. Accordingly, the governing bodies
383 of elite-level referees now implement regular fitness testing17 and supervised training sessions21 in an attempt to control and regulate the physical fitness of referees. For example, both FIFA and UEFA now systematically assess the fitness level of their affiliated referees with a battery of field tests consisting of 50 and 200 m sprints and 12 min running (12 MRT) for distance.10 Since FIFA and UEFA have adopted these tests, many other national referees’ associations have also used this test battery as evaluation tool for fitness and physical performance.17,22 However, although the 50, 200 m and 12 MRT have been widely used by national referees’ associations around the world, only few studies have evaluated the relevance of these tests to match performance.5,17 Additionally, to our knowledge, no scientific studies have examined the criterion validity of these tests for referees. Therefore, the first aim of this study was to investigate possible age-related difference in physiological and field tests performance in elite soccer referees of different officiating experience. Furthermore, since the 12 MRT10 is the most popular field test for aerobic fitness in soccer refereeing, the second aim of this study was to determine the criterion validity of 12 MRT in a group of highly competitive officials. The research hypothesis was that physical and physiological performance would be decreased with age in elite soccer referees.
Material Subjects The research examined the performance and physiological responses of 45 elite referees enrolled in the Referees Technical Committee of the Royal Spanish Soccer Federation. All subjects (n = 45, see Table 1) were experienced (>10 years professional level) elite-level referees from the Spanish Soccer Referees Association (CTA). Ten of the referees who participated in this study had previously officiated international matches. All referees were in good health and had taken part in the supervised physical training program that we had implemented.
Methods Experimental design Prior to exercise testing each referee was required to undertake a medical examination, which
384 Table 1
J.A. Casajus, C. Castagna Anthropometrical characteristics of entire group (n = 45) and Y, A and O groups
Variables
Group All [n = 45]
Age (year) Height (cm) Body Mass (kg) Skinfolds sum (mm) % Fat
35.5 178.3 75.1 83.2 11.3
± ± ± ± ±
4.4 5.0 6.6 20.5 2.15
Young [n = 15] 30.4 178.7 73.4 80.8 11.1
± ± ± ± ±
AO
1.5 5.4 6.1 11.3 0.56
Average [n = 17] 35.8 179.4 77.3 81 11.1
± ± ± ± ±
YO
1.2 4.8 6.9 14.1 0.53
Old [n = 13] 40.4 176.4 74.3 88.9 11.9
± ± ± ± ±
2.5YA 4.5 6.2 32.8 0.60
A Significantly
different from Average group P < 0.05; Y significantly different from Young group P < 0.05; O significantly different from Old group P < 0.05.
included blood screening, electro-cardiogram at rest, basal lung function tests and blood pressure measurements. In addition, all referees provided a written informed consent after they were given a detailed explanation as to the nature of the research. All tests were conducted during the preseason of the 2001—2002 Spanish championship (in August, after 4 weeks of training). The referees were all familiar with the testing procedures undertaken in this study. Specifically, all referees undertook the field test and laboratory test protocols in the 6 months prior to the study. The referees used in this study were eligible to officiate in the professional Spanish championships (Liga 1a Division and Liga 2a Division, first and second soccer division, respectively) and were members of the CTA. In Spain, only 45 referees are selected to officiate in the Liga 1a and 2a Championships each year. These referees are selected on the basis of their refereeing ability and physical fitness. Furthermore, referees who are older than 45 are not eligible to be selected to officiate in these championships. Due to the rigorous selection process and to the high level of play taking place in the Liga 1a and 2a championships, the referees in this study were considered to be representative of elite-level soccer referees. In order to test the likelihood of age-related variations in fitness performance, the referees were grouped into three age-group categories: young (Y, 27—32 years n = 15), average (A, 33—38 years, n = 17) and old (O, 39—45 years, n = 13).23 The selection for the grouping categories was based on the methods proposed by Castagna et al.,23 addressing similar populations of elite-level soccer referees. The Y, A and O groups were matched for both training intensity and volume performed during the three months preceding the commencement of this cross-sectional study.23 The age range considered for the O group was chosen, because the CTA considers 39 as the higher age limit to get access or aspire to elite-level soccer refereeing. The Y group was formed as representative
of the third decade of life considered as the age when morphological and physiological declines in skeletal muscle performance begin.11 These three groups were then tested using the field fitness test battery in use by UEFA at the time of this investigation10 (i.e., 50, 200 and 12 min run test) and with laboratory-based tests for aerobic fitness (i.e., treadmill running-test for VO2max and ventilatory threshold (VT) assessment). These measures of aerobic fitness were taken because recent studies have clearly shown that speed at selected lactate thresholds and VO2max are associated with physical match-performance in elite-level soccer referees.17,18 The Ethics Committee of the University of Zaragoza (Spain) and the CTA approved the research design.
Laboratory testing Aerobic fitness tests were performed at the same time of the day (09:00—14:00 h) under similar environmental conditions (temperature ∼20 ◦ C; relative humidity 45—55%; barometric pressure ∼720 mmHg). All subjects refrained from performing physical activity during the 24 h period before each test. Each subject performed an incremental exercise test to exhaustion on a motorised treadmill (Jaeger Laufergotest, Germany) for determination of ventilatory threshold (VT),24 maximal ventilation (VEmax ) and maximal oxygen uptake (VO2max ). Attainment of VO2max was considered when at least two of the following criteria were satisfied: (1) plateau in VO2 despite an increase in exercise intensity; (2) HR greater than 90% of the age-predicted maximal value (220-age); (3) a respiratory exchange ratio (RER) greater than 1.15. Following a 5 min warm-up, the incremental treadmill protocol commenced at a workload of 8 km h−1 and a 1% grade. The treadmill speed
Fitness performance in soccer referees
385
was increased by 1 km h−1 every minute until volitional exhaustion. The heart rate was monitored electrocardiographically and displayed simultaneously on the screen of the oscilloscope (Hellige, Servimed, Germany). Gas exchange measurements were made breath-by-breath during the test and for 3 min during the recovery (Medical GraphicsCardiopulmonary Exercise System CPX, USA). The speed at exhaustion was assumed as peak treadmill velocity (PTV) according to Noakes.25
referees throughout the test at regular intervals (i.e., every 2 min). Distance covered was assessed making subjects remain on the athletic-track spot reached at end of the 12 min run and counting laps performed plus possible extra space (rounded to the nearest metre using a measurement wheel). Experienced and qualified fitness trainers implemented all tests on behalf of the CTA.
Anthropometrical measurements
Data are presented as mean and standard deviation. The Kolmogorov—Smirnov test was applied to ensure a normal distribution of parametric data. One-way analysis of variance (ANOVA) with a Tukey HSD post hoc comparison was used to determine significant differences between the young, average and old groups of referees. The relationships between variables of interest were detected using Pearson’s correlation coefficient (r) and estimations were performed using bivariate regression equations. Significance was set for the calculations at 5% (P ≤ 0.05). All calculations were performed using Statistica software package (Version 6.01 StatSoft, Tulsa, USA).
Standard anthropometrical variables (stature, body mass, biceps-epicondylar humerus and femur width, arm flexed and extended and calf girths, and triceps, subscapular, supraspinal, abdominal, front thigh and medial calf skinfolds) were obtained on all subjects by a trained anthropometrist, following methods suggested by the International Society for the Advancement of Kinanthropometry.26 Anthropometric instruments used in this study included a stadiometer, scale, small sliding calliper (Rabonne Chesterman, Silverflex, UK), anthropometric tape (GPM Siber-Hegner Maschinen, Switzerland) and skinfold calliper (Holtain LTD, Crymych, UK). Percentage of body fat was estimated according to Carter’s equation.27 Sum of six skinfolds was also used as index of adiposity.
Field tests Field tests were performed on a tartan athletic track 5 days after the cardiorespiratory test. Each testing session was performed with well-rested (moderate exercise during the 24—48 h preceding testing, i.e., 20—30 min running at 70% of individual maximal heart rate) subjects and all test bouts were completed at the period of the day when most Spanish matches are played (16:00—18:00 h). Furthermore, the environmental conditions during testing sessions were similar to those experienced by referees during matches. The field tests were conducted in the following order: 50, 200 m and 12 MRT. Ten minutes of active rest (walking-jogging) was provided between the 50 m and the 200 m test and 15 min of rest was allowed between the 200 m sprint and the start of the 12 MRT. The 50 and 200 m times were assessed with the aid of photo-cells (Racetime 2 Kit SF, Bolzan, Italy), whereas 12 MRT times were clocked with an electronic stopwatch (Casio HS 30 W, Tokyo, Japan). The 12 MRT consisted in covering as much as distance as possible running for 12 min on a tartan athletic-track. Only 10 referees at a time were tested and time passage feedback was provided to
Statistical analyses
Results The anthropometrical and physiological characteristics of the participants to this study are shown in Tables 1 and 2, respectively. The mean age of each of the groups was significantly different (P < 0.001). No significant group differences were observed for height, body mass, skinfolds sum and percentage of body fat (% Fat) (P > 0.05). Referees in the O group were significantly slower in the 50 m sprint compared to Y group (6.90 ± 0.31 and 6.62 ± 0.18 s, respectively, P < 0.001). No significant age effects were evident for 200 and 12 MRT performances (P > 0.05). Heart rate at VT (VT% HRmax ) and relative PTV at VT (VT% PTV) of the Y group was significantly different from that of the O group (P < 0.01). Speed at VT was significantly higher in the A group compared to the O group (15.5 ± .9 and 14.5 ± 1.4 s, respectively, P < 0.001). Both relative and absolute VO2max was not significantly different across the age groups (P > 0.05). Twelve MRT performance was moderately related to VO2max (r = 0.46, P = 0.002, see Fig. 1), VT (km h−1 ) (r = 0.49, P < 0.001) and PTV (r = 0.60, P < 0.001, see Fig. 2). The 200 m sprint performance was significantly correlated to %PTV at VT (r = −0.51, P < 0.001). The 50 m performance was significantly related to 200 m performance (r = 0.79, P = 0.001).
386 Table 2
J.A. Casajus, C. Castagna Physiological and fitness tests results of the entire group (n = 45) and Y, A and O groups
Variables
Group All [n = 45] −1
VO2 (L min ) VO2 (ml kg−1 min−1 ) VEmax (l min−1 ) VT (km h−1 ) PTV (km h−1 ) HRmax (beat min−1 ) VT (ml kg−1 min−1 ) VT %VO2max VT% HRmax VT% PTV 50 m (s) 200 m (s) 12 MRT (m) O Significantly
4.1 54.9 137 15.1 17.9 182 46.3 84.4 92.5 84.29 6.76 28.95 2984
± ± ± ± ± ± ± ± ± ± ± ± ±
0.4 3.9 15 1.1 0.9 9 3.9 5.4 3.0 4.29 0.25 1.28 125
Young [n = 15] 4.1 55.3 139 15.2 17.8 185 47.3 85.7 94.1 85.7 6.62 28.43 2986
± ± ± ± ± ± ± ± ± ± ± ± ±
0.4 4.5 15 1.0 1.0 7 3.4 5.8 2.0O 3.7O 0.18O 1.02 122
Average [n = 17] 4.2 55.3 137 15.5 18.2 181 46.6 84.3 92.3 85.2 6.78 29.02 2978
± ± ± ± ± ± ± ± ± ± ± ± ±
0.3 3.3 17 .9O 0.8 10 3.1 3.7 2.5 2.9O 0.20 1.02 97
Old [n = 13] 4.0 53.8 134 14.5 17.8 180 44.7 83.0 91.0 81.6 6.90 29.47 2988
± ± ± ± ± ± ± ± ± ± ± ± ±
0.4 3.8 15 1.4 1.0 9 4.9 6.7 3.6 5.4 0.31 1.60 165
different from Older group; P < 0.05.
Discussion
Figure 1 Relationship between VO2max (ml kg−1 min−1 ) and 12 MRT (r = 0.46, P = 0.002).
Figure 2 Relationship between VO2max (ml kg−1 min−1 ) and PTV (r = 0.60, P < 0.001).
The results of this study showed that there were age-related differences in selected components of physical fitness in this group of elite-level soccer referees. Specifically, both short maximal anaerobic sprinting (50 m sprint) and sub-maximal (VT) aerobic measures were significantly better in younger referees compared to their older counterparts. However, both VO2max and 12 MRT, the variables that have previously been shown to strongly relate to match running performance,17,19 showed no significant difference among the age groups. These findings suggest that older referees possess aerobic performances similar to those showed by their younger colleagues. In this study, we found no age-related effects on VO2max . The present results are in contrast to previous research that has reported age-related decrements in VO2max of 5—15% per decade after the age of 25 years.12 The age-related decrement in VO2max has been mainly attributed to decreased cardiac output12,28 and decreased heart contractility.16,29 However, we did not observe any changes in HRmax between the age groups in this study. Similarly, there were no differences in any of the anthropometrical measures between the young, average or older referees in this study. It is possible that the maintenance of appropriate body composition may have also contributed to the maintenance of aerobic fitness in the older referees.14 The small but significant correlation between body fat percentage and relative VO2max (r = −0.34, P = 0.02) supports this suggestion. It is possible that the history of regular high-intensity training among this group of older elite-level referees may have prevented or
Fitness performance in soccer referees diminished the anticipated decline in VO2max that is common in a non-elite population.30 A lower sub-maximal exercise performance was observed in the older referees compared to their younger counterparts. Specifically, the O group showed a significantly lower running velocity (km h−1 ) and %PTV at VT compared to the Y group. These results are in contrast to previous research13 that reported neither age-related declines in VO2 nor increments in % of VO2max during sub-maximal aerobic exercise. The decline in sub-maximal exercise performance observed in older referees is in line with that which has been reported in non-professional cyclists.11 Although the mechanisms underlying these age-related changes are not understood, it is possible that an age-related reduction in muscle power was the cause for the reduction in sub-maximal running performance. In fact, several previous studies have shown a strong relationship between neuromuscular efficiency and sub-maximal running performance in active individuals.31—33 In this study, we found that 50 m sprint performance was decreased in the older group of referees. This reduction in neuromuscular power might also explain the reduced sub-maximal running capacity in the older group of referees. Previous studies have suggested that there is a strong relationship between neuromuscular performance and sub-maximal aerobic performance.31—33 In support, we observed a moderate correlation between 50 m performance and VT (km h−1 ) (r = −0.41 P = 0.05) and VT (ml kg−1 min−1 ) (r = −0.55 P < 0.001). Taken collectively, these results might suggest that the reduction in neuromuscular power with ageing is related to the reduced sub-maximal aerobic performance in older referees. However, caution must be taken when interpreting these suggestions as the correlation analysis does not demonstrate a cause—effect relationship. The possible effects of the reduced sprint and sub-maximal aerobic performance on match physical performance are difficult to quantify accurately. In fact, 50 m sprint performance has been previously reported to not be significantly related to match physical performance.17 Conversely, higher speeds at selected lactate threshold have been reported to be related to greater match coverage in elite-level soccer referees.18 As total-match distance has been related to optimal positioning in soccer refereeing,1 higher speed at VT could be of some benefit for older referees.17,19 Bangsbo et al. have recently reported that older top-class referees (age 40—46 years) do not have greater difficulty in keeping up with the game when compared to their younger counterparts (age 29—34 and 35—39
387 years).34 Probably, 12 MRT and VO2max levels similar to those found in the younger counterparts may compensate for the reported under-performance in VT. In this study, there was a moderate relationship between the 12 MRT, VO2max (r = 0.42, P = 0.002) and sub-maximal (VT) aerobic fitness (r = 0.49, P < 0.001). Indeed, the correlation between the 12 MRT and VO2max was lower than the values reported in previous research.23,35 It is possible that the lower correlation between these variables in this study compared to previous research (VO2max standard deviations ±3.9 and 5.91 ml kg−1 min−1 , respectively) is that there is a greater level of homogeneity of the aerobic fitness levels of the referees in this study. 23 In agreement with previous research, 25,36 this study also demonstrated that PTV has a stronger relationship with aerobic-performance than other component of aerobic-fitness measured in this study. In fact, previous studies have shown PTV to be associated with endurance performance over a large range of distances from 1500 m through to the marathon.25,36 The likely explanation for the higher relationship between 12 MRT and PTV found in this study is that PTV may reflect the interaction between an individual’s VO2max , exercise economy, anaerobic capacity and muscle power and thus better characterising aerobic performance.25,31—33,36 This test may be a useful measure for assessing changes in performance and fitness changes in elite referees. Furthermore, since the 12 MRT is usually conducted in the outdoors, performance may be affected by environment changes and therefore may not be sufficiently reliable or sensitive to small changes in performance. The VO2max levels (54.9 ± 3.9 ml kg−1 min−1 ) of the elite Spanish soccer referees in this study are considerably higher than those previously reported for competitive level referees of other countries.1 For example, the mean VO2max values of 49.30 ± 8.0 and 50.9 ± 5.7 ml kg−1 min−1 have been reported in elite-level Italian referees19 and English Premier League referees,7 respectively. Similar values were reported for Danish top-class referees with the mean VO2max of 46.3 ml kg−1 min−1 (range: 40.9—56 ml kg−1 min−1 ).5 However, the VO2max levels measured in this study are approximately 16% lower than those reported by Casajus37 for the same period of the season in Spanish elite-level soccer players (65.5 ± 8.0 ml kg−1 min−1 ) competing in the same League. The reasons for the higher VO2max levels found for this group of officials are difficult to determine. It is possible that the higher VO2max levels observed in this study may be due to the supervised fitness training performed throughout
388 the competitive year,28,38 daily lifestyle39 and/or genetic factors.12 The results of this study showed that older elitelevel referees may be able to limit the expected age-related performance decrements in both aerobic and anaerobic performance usually reported for sedentary people. Additionally, they show that older referees are able to maintain physical fitness levels that have been suggested to be appropriate for coping with match demands.17,40
J.A. Casajus, C. Castagna
13.
14.
15.
16.
Practical implications • Training should focus on training maximal aerobic power and aerobic endurance development of elite-level referees of all ages. • Trainers of referees should focus on control of the body mass and composition of older referees. • Training of referees should also include activities that focus on increasing explosivestrength and running speed.
17.
18.
19.
20.
21.
References 22. 1. Stølen T, Chamari K, Castagna C, et al. Physiology of soccer: an update. Sports Med 2005;35(6):501—36. 2. D’Ottavio S, Castagna C. Physiological load imposed on elite soccer referees during actual match play. J Sports Med Phys Fitness 2001;41(1):27—32. 3. D’Ottavio S, Castagna C. Analysis of match activities in elite soccer referees during actual match play. J Strength Cond Res 2001;15(2):167—71. 4. Johnston L, McNaughton L. The physiological requirements of soccer refereeing. Aust J Sci Med Sport 1994;26(3—4):67—72. 5. Krustrup P, Bangsbo J. Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training. J Sports Sci 2001;19:881—91. 6. Catterall C, Reilly T, Atkinson G, et al. Analysis of work rate and heart rates of association football referees. Br J Sports Med 1993;27:153—6. 7. Weston M, Brewer J. A study of the physiological demands of soccer refereeing. J Sports Sci 2002;20:59— 60. 8. Bangsbo J, Norregaard L, Thorso F. Activity profile of competition soccer. Can J Sport Sci 1991;16(2):110—6. 9. Helsen W, Bultynck JB. Physical and perceptual-cognitive demands of top-class refereeing in association football. J Sports Sci 2004;22:179—89. 10. Eissmann HJ, D’Hooghe M. Sports medical examinations. In: The 23rd man: sports medical advice for football referees. Leipzig, Germany: Gers¨ one-Druck; 1996. 11. Mattern CO, Gutilla MJ, Bright DL, et al. Maximal lactate steady state declines during the aging process. J Appl Physiol 2003;95(6):2576—82. 12. Taylor AH, Cable NT, Faulkner G, et al. Physical activity and older adults: a review of health benefits and the effec-
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
tiveness of interventions. J Sports Sci 2004;22(8):703— 25. Wiswell RA, Jaque SV, Marcell TJ, et al. Maximal aerobic power, lactate threshold, and running performance in master athletes. Med Sci Sports Exerc 2000;32(6):1165— 70. Rogers MA, Hagberg JM, Martin WH, et al. Decline in VO2max with ageing in masters athletes and sedentary men. J Appl Physiol 1990;68:2195—9. Coggan AR, Abduljalil AM, Swanson SC, et al. Muscle metabolism during exercise in young and older untrained and endurance-trained men. J Appl Physiol 1993;75:2125—33. Heath GW, Hagberg JM, Ehsani AA, et al. A physiological comparison of young and older endurance athletes. J Appl Physiol 1981;51(3):634—40. Castagna C, Abt G, D’Ottavio S. Relation between fitness tests and match performance in elite Italian soccer referees. J Strength Cond Res 2002;16(2):231—5. Castagna C, Abt G, D’Ottavio S. The relationship between selected blood lactate thresholds and match performance in elite soccer referees. J Strength Cond Res 2002;16(4):623—7. Castagna C, D’Ottavio S. Effect of maximal aerobic power on match performance in elite soccer referees. J Strength Cond Res 2001;15(4):420—5. Williams AM, Lee D, Reilly T. A quantitative analysis of matches played in the 1991—92 and 1997—98 seasons. London: The Football Association; 1999. Weston M, Helsen W, MacMahon C, et al. The impact of specific high-intensity training sessions on football referees’ fitness levels. Am J Sport Med 2004;32(1 Suppl.):54s—61s. Rontoyannis GP, Stalikas A, Sarros G, et al. Medical, morphological and functional aspects of Greek football referees. J Sports Med Phys Fitness 1998;38:208—14. Castagna C, Abt G, D’Ottavio S, et al. Age-related effects on fitness performance in elite-level soccer referees. J Strength Cond Res 2005;19(4):785—90. Beaver WL, Wasserman K, Whipp BJ. A new method for detecting anaerobic threshold by gas exchange. J Appl Physiol 1986;60(6):2020—7. Noakes TD. Implications of exercise testing for prediction of athletic performance: a comtemporary perspective. Med Sci Sports Exerc 1988;20(4):319—30. Eston RG, Reilly T. Kinanthropometry and exercise physiology laboratory manual: tests, procedures and data: anthropometry, vol. 1. London: Routledge; 2001. Carter JEL. Physical structure of olympic athletes. Part I. The Montreal olympic games. Anthropological project. Basel: S. Karger; 1982. Proctor DN, Joyner MJ. Skeletal muscle mass and the reduction of VO2max in trained older subjects. J Appl Physiol 1997;82(5):1411—5. Higginbotham MB, Morris KG, Williams RS, et al. Physiologic basis for the age-related decline in aerobic work capacity. Am J Cardiol 1986;57(15):1374—9. Rognmo Ø, Hetland E, Helgerud J, et al. High intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease. Eur J Cardiovasc Prev Rehabil 2004;11(3):216—22. Paavolainen L, Hakkinen K, Hamalainen I, Nummela A, Rusko H. Explosive-strength training improves 5-km running time by improving running economy and muscle power. J Appl Physiol 1999;86(5):1527—33. Nummela AT, Paavolainen LM, Sharwood KA, et al. Neuromuscular factors determining 5 km running performance
Fitness performance in soccer referees
33.
34.
35. 36.
and running economy in well-trained athletes. Eur J Appl Physiol Occup Physiol 2006;97(1):1—8. Paavolainen LM, Nummela AT, Rusko HK. Neuromuscular characteristics and muscle power as determinants of 5-km running performance. Med Sci Sports Exerc 1999;31(1):124—30. Bangsbo J, Mohr M, Krustrup P. Physical capacity and match performance of top-class referees in relation to age. J Sports Sci 2004;22:524. Cooper KH. A means of assessing maximal oxygen intake. J Am Med Assoc 1968;(203):201—4. Noakes TD, Myburgh KH, Schall R. Peak treadmill running velocity during the VO2max test predicts running performance. J Sports Sci 1990;8(1):35—45.
389 37. Casajus J. Seasonal variation in fitness variables in professional soccer players. J Sports Med Phys Fitness 2001;41:463—9. 38. Lawrenson L, Hoff J, Richardson RS. Aging attenuates vascular and metabolic plasticity but does not limit improvement in muscle VO2max . Am J Physiol Heart Circ Physiol 2004;286(4):1565—72. 39. Aoyagi Y, Katsuta S. Relationship between the starting age of training and physical fitness in old age. Can J Sport Sci 1990;15(1):65—71. 40. Weston M, Bird S, Helsen W, et al. The effect of match standard and referee experience on the objective and subjective match workload of English Premier League referees. J Sci Med Sport 2006;9(3):256—62.
Available online at www.sciencedirect.com