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Level of competitive success achieved by elite athletes and multi-joint proprioceptive ability
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Journal of Science and Medicine in Sport xxx (2013) xxx–xxx
Contents lists available at ScienceDirect
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Original research
Level of competitive success achieved by elite athletes and multi-joint proprioceptive ability Jia Han a,b,∗ , Gordon Waddington b , Judith Anson b , Roger Adams c a b c
Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, China Faculty of Health, University of Canberra, Australia Faculty of Health Sciences, University of Sydney, Australia
a r t i c l e
i n f o
Article history: Received 25 July 2013 Received in revised form 8 November 2013 Accepted 28 November 2013 Available online xxx Keywords: Proprioception Movement discrimination Elite athletes Performance Training
a b s t r a c t Objectives: Proprioceptive ability has been suggested to underpin elite sports performance. Accordingly, this study examined the relationship between an athlete’s proprioceptive ability, competition level achieved, and years of sport-specific training. Design: Cross-sectional study. Methods: One hundred elite athletes, at competition levels ranging from regional to international, in aerobic gymnastics, swimming, sports dancing, badminton and soccer, were assessed for proprioceptive acuity at the ankle, knee, spine, shoulder, and finger joints. An active movement extent discrimination test was conducted at each joint, to measure ability to discriminate small differences in movements made to physical stops. Results: Multiple regression analysis showed that 30% of the variance in the sport competition level an athlete achieved could be accounted for by an equation that included: ankle movement discrimination score, years of sport-specific training, and shoulder and spinal movement discrimination scores (p < 0.001). Mean proprioceptive acuity score over these three predictor joints was significantly correlated with sport competition level achieved (r = 0.48, p < 0.001), highlighting the importance of proprioceptive ability in underpinning elite sports performance. Years of sport-specific training correlated with an athlete’s sport competition level achieved (r = 0.29, p = 0.004), however, proprioceptive acuity was not correlated with years of sport-specific training, whether averaged over joints or considered singly for each joint tested (all r ≤ 0.13, p ≥ 0.217). Conclusions: Proprioceptive acuity is significantly associated with the performance level achieved by sports elites. The amount of improvement in proprioceptive acuity associated with sport-specific training may be constrained by biologically determined factors. © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
1. Introduction Proprioceptive sensitivity is the ability to integrate sensory information from mechanoreceptors and thereby determine body position and movements in space.1,2 Having good proprioceptive ability is more important for tasks with high skill demand than it is for normal activities,3–5 suggesting that it may underlie elite athletic performance. However, there is presently little evidence to support this hypothesis. Although some research has shown athletes to have superior proprioceptive ability compared to non-athletic controls,3–5 the tests have been conducted at one joint, and in one sport. As a consequence, it has not been determined whether proprioceptive ability determined over multiple body joints, for athletes in
∗ Corresponding author. E-mail addresses: [email protected], [email protected] (J. Han).
different sports, is related to how good an athlete is, as reflected in the competition level they have achieved. Superior proprioceptive ability in athletes has been attributed to prolonged periods of athletic training.3,4,6 Because few studies have examined the relationship between proprioceptive ability and years of sport-specific training, it is not known whether this superior proprioceptive ability in athletes is inherently determined and selected for by competitive success, or whether it arises from extensive training. Recently, Daneshjoo et al.7 reported that knee proprioception at 45 and 60◦ was significantly improved by eight weeks of specifically designed warm up program, suggesting that proprioception may be enhanced by sport-specific training. If enhanced proprioceptive ability is an outcome of years of sport-specific training, proprioceptive sensitivity and years of sport-specific training should be significantly correlated. Conversely, it has been argued that proprioception cannot be trained,8 suggesting that no correlation would be apparent.
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2 Table 1 Participant information.
Elite competition level (n)
Aerobic gymnastics (8 M, 12 F) Swimming (10 M, 10 F) Sports dancing (7 M, 13 F) Badminton (12 M, 8 F) Football (Soccer) (13 M, 7 F) Control group (10 M, 10 F)
Sport-specific training (years)
Body mass (kg)
Height (m)
i
ii
iii
Mean
Range
Mean
Range
Mean
4 4 10 7 14 –
10 11 7 11 4 –
6 5 3 2 2 –
6 14 5 9 10 –
3–13 6–15 2–16 4–12 6–13 –
60 70 53 66 67 61
48–75 56–92 45–75 57–76 52–85 51–83
1.69 1.77 1.67 1.77 1.74 1.71
Age (years)
Range 1.58–1.78 1.66–1.92 1.56–1.80 1.64–1.86 1.61–1.90 1.63–1.82
Mean
Range
21 20 20 20 21 21
18–23 19–22 18–23 18–22 20–22 20–22
For elite competition level, i represents Chinese national top 32 or regional top 3; ii represents Chinese national top 16; and iii represents Chinese national top 6 and competing internationally.
The aim of the current study was to examine the relationship between proprioceptive ability, competition level achieved, and years of sport-specific training. Elite athletes from 5 sports – aerobic gymnastics, swimming, sports dancing, badminton, and soccer – all actively competing at regional, national or international level, were recruited, and proprioception tests conducted on 5 body sites: the ankle, knee, spine, shoulder and fingers. In the present study, a set of tests, each using a form of the active movement extent discrimination apparatus (AMEDA), was employed to assess proprioceptive ability. The AMEDAs were developed based on the principle of replicating functional movement,9 i.e., using active rather than passive movement, testing in normal weight-bearing conditions, moving at a steady pace, and without physical constraints to non-tested limbs, in order to maximize the ecological validity of proprioception testing. The AMEDA method for assessing proprioceptive acuity has been validated by being able to: identify subjects with ankle ligament laxity,10 evaluate the effect of training on knee proprioception,11 show different patterns of spine flexion discrimination in subjects with spinal disc replacement,12 reveal a correlation between shoulder proprioception with humeral torsion in adolescent baseball players13 and show superiority for the non-dominant hand/hemisphere system in the utilization of pinch movement proprioception.14,15 2. Methods The project was approved by the University of Canberra Committee for Ethics in Human Research (approval number: CEHR 11-47) and written informed consent was obtained from participants before testing sessions commenced. The organizations that provided funding for this project had no role in recruitment, data collection, analysis, interpretation, or approval for submission for publication. Participant information is presented in Table 1. Recruitment was from sports where there were sufficient elite athletes available at the time of testing. One hundred right-handed athletes competing at high levels in five different sports and twenty right-handed, non-athletic controls were recruited from advertisements posted throughout the Shanghai University of Sport. The athletes who volunteered had a minimum of two years of sport-specific training, and all were actively competing in their chosen sport. An athlete’s sport competition level was determined as their best level achieved within the prior year, at three elite levels. These were, from lowest to highest: (i) Chinese national top 32 or regional top 3; (ii) Chinese national top 16; and (iii) Chinese national top 6 and competing internationally. Given the selection pool for athletes in China, all individuals reaching these levels can be regarded as elites.16 A group of healthy university students without any history of specialized training experience specific to a particular sport was recruited as non-athletic controls. As all students participated in the weekly 90 min physical education classes held at the Shanghai University of Sport, they were physically able to undertake the proprioception
tests. All participants were asked to adhere to their normal routine of training, sleeping, eating and hydration prior to doing the AMEDA tests. The Edinburgh Handedness Inventory17 was used to determine right-handedness. When questioned regarding footedness, all participants responded that they would also use their right foot to kick a ball. A health questionnaire was used to rule out the presence of significant injuries within the past 6 months or a diagnosis of neurological disease, specifically Parkinson’s disease, brain damage, chronic pain, Down’s syndrome or diabetic neuropathy.3 A purpose-built AMEDA was employed for the proprioception tests at each body site (Fig. 1). The apparatus employed here has been described previously for the ankle,10 the knee,11 the spine,12 the shoulder13 and the fingers.18 Reliability of the scores (Interclass Correlation Coefficient) generated by the AMEDA tests has been determined as ranging from 0.82 to 0.96.14,18,19 The series of AMEDAs were used to generate a set of 5 end positions at each joint tested. The 5 predetermined displacements from smallest to largest were: ankle inversion = 10, 11, 12, 13 and 14◦ , knee flexion = 37, 38, 39, 40 and 41◦ , spine flexion = 20.9, 21.5, 22.1, 22.6 and 23.2◦ , shoulder flexion = 170.6, 171.2, 171.7, 172.3 and 172.9◦ , and thumb-index finger pinch extent = 5.5, 8.0, 10.5, 13.0 and 15.5 mm. A position number (1, 2, 3, 4 or 5) was assigned to each movement displacement in order, so that participants were able to use the assigned position numbers to make their responses during the test. The protocol for testing at each joint consists of a standardized familiarization session and a data collection session. During the familiarization session before data collection, each participant was informed that they would experience the five movement distances in order, from the smallest (moving to position 1) to the largest (moving to position 5), three times in succession, to ensure participants were focused on the relevant dimension. After the 15-trial familiarization, participants then undertook 50-trials of testing, in which all five positions were presented 10 times, in a random order. During testing, participants were asked to make a judgment as to the position number (1, 2, 3, 4 or 5) of each movement as soon as they returned the testing joint to the start position, without feedback being given regarding the correctness to the judgment they made for each trial. That is, the participants used their memory of the 5 movement displacements from the familiarization trials to enable them to evaluate the current stimulus and thus make a numerical judgment about each stimulus as it was presented. This task was thus a single stimulus, or absolute judgment task, wherein a single stimulus was presented and single response was made on each trial. The psychophysical method employed in the current study fulfills the validity criteria for assessing active movement function, with sufficient trials to determine participants’ ability to use proprioceptive information when they discriminate a set of movements.20,21 The procedure for spine flexion discrimination is described here as an example. Participants wore a loose shirt, short pants and were
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Fig. 1. Active movement extent discrimination apparatus for testing proprioception at the 5 body sites: a, spine flexion; b, shoulder flexion; c, knee flexion; d, ankle inversion; and e, finger pinch.
barefoot. They stood facing the height-adjustable spine AMEDA with their big toes aligned with a tape marker, to maintain the same original testing position for each participant. For each trial of the spine AMEDA test, participants made an active spine flexion movement at a steady pace, starting from the neutral standing position with the fixed stop against their thoracic spine, and moved their trunk forward until their sternum touched the stepper motor knob. Participants were unable to see the stepper motor knob at any time throughout the movement. After returning to the upright position at the same pace, participants identified the extent of spine flexion they had just experienced, out of five possible distances. The similar procedures for AMEDA testing of active movements of ankle inversion, knee flexion, shoulder flexion and finger pinch discrimination have been described previously.14 The testing order of the different joints on the dominant right side, and at the spine, was randomized for each participant. Participants were allowed to have a short break between joint sites to avoid fatigue. The complete test at each body site, with 15 familiarization trials and 50 test trials, took 10 min, and completing all 5 movement discrimination tasks required approximately 1 h. To obtain an accuracy metric, non-parametric signal detection analysis was used to produce pair-wise Receiver Operating Characteristic (ROC) curves. Stimulus–response matrices were constructed, with cell entries representing the frequency with which each response was made for each stimulus. Discrimination sensitivity between adjacent positions was calculated in a pair-wise fashion (i.e., 1–2, 2–3, 3–4, 4–5). Thereafter, the mean pair-wise Area Under the Curve (AUC) value was calculated using SPSS software V.18, to give each participant a single discrimination sensitivity score at a particular joint. The AUC score, derived from the ROC curve, provides an unbiased estimate of the ability of an individual to discriminate between the five different stimuli.22 AUC values range from 0.5, which is equivalent to chance responding, to 1.0, representing perfect ability to discriminate between the 5 different movement extents. Scores were obtained from the AMEDA tests of proprioceptive sensitivity at the ankle, knee, shoulder, spine and fingers for the 20 participants in each of the sports groups, and for the 20 non-athletic controls, and the means and 95% confidence intervals (CIs) were calculated for each of the groups. Thereafter, scores were entered into a repeated-measures ANOVA, with planned contrasts used to compare each of the five sport groups with the non-athlete control group. Where the Mauchly Sphericity Test result was significant, the Greenhouse–Geisser corrected F-value was used.
Pearson correlations were calculated to assess the relationship between movement discrimination scores of each of the five body sites and sports competition level, years of sport-specific training, age, height and body mass. The sample size of 100 in the present study fulfilled the minimum sample size requirement for linear regression (n ≥ 50 + 8 × m, where m = 6 independent variables: the movement discrimination scores at the ankle, knee, spine, shoulder and fingers, and years of sport-specific training).23 Accordingly, step-wise multiple regression analysis was conducted, with competition level as the dependent variable and AUC proprioception sensitivity scores at the ankle, knee, shoulder, spine, and finger, and years of sportspecific training entered as independent variables. 3. Results The mean and the upper and lower bounds of the 95% CIs for the AUC proprioceptive acuity score of each sport group were: aerobic gymnastics 0.680 (0.670–0.690), swimming 0.662 (0.652–0.672), sports dancing 0.667 (0.657–0.677), badminton 0.666 (0.656–0.676) and soccer 0.674 (0.664–0.684). The mean and the 95% CI for the non-athletic control group were 0.641 (0.631–0.651). Mean AUC across 5 joints for athletes in every sport was significantly greater than for the non-athletic control group, with the p-values for comparisons with aerobic gymnastics, swimming, sports dancing, badminton and soccer being 0.001, 0.003, 0.001, 0.001 and 0.001, respectively. Correlation values showed that sport competition level was significantly correlated with ankle (r = 0.43, p < 0.001) and shoulder proprioceptive acuity scores (r = 0.24, p = 0.015), but not with proprioceptive acuity at the spine (r = 0.15, p = 0.149), knee (r = −0.02, p = 0.866) or fingers (r = −0.09, p = 0.369). There was no significant relationship between years of sport-specific training and proprioceptive acuity score for any of the joints tested (all r ≤ 0.13, p ≥ 0.217), however, years of sport-specific training was significantly correlated with sport competition level (r = 0.29, p = 0.004), suggesting that while sport skill improves with years of training, proprioceptive acuity does not. The lack of significant correlations in the observed pattern of relationships between the proprioception scores for different joints (all r ≤ 0.12, p ≥ 0.219) further supports the notion of proprioception as joint-specific, rather than proprioceptive acuity being a global attribute.20 Multiple regression was used to determine whether an athlete’s years of training and joint proprioceptive acuity scores could
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Fig. 2. Mean proprioceptive acuity scores from the ankle, shoulder and spine active movement extent discrimination tasks, for the three competition level subgroups within each of the five sports. Being at a higher competition level was associated with better proprioceptive acuity, measured as averaged Area Under the Curve (AUC) scores over the three joints. Scores from the highest level athletes, Chinese national top 6 and competing internationally are represented by filled triangle symbols, Chinese national top 16 by filled circles, and for the Chinese national top 32 or regional top 3, filled squares are used.
predict their competition level. A significant prediction equation was found (F4,95 = 11.5, p < 0.001) that accounted for 30% of the variance in competition level (adjusted R2 = 0.30). The model produced four predictors that added significant independent amounts to the total variance that could be accounted for in sport competition level. The predictor variables were ankle proprioception AUC score (18%), years of sport-specific training (6%), shoulder proprioception AUC score (4%) and spine proprioception AUC score (2%). The resulting equation was: Predicted Sport Competition Level = 6.12 × AUC(Ankle) + 0.05 × Years of sport-specific training + 4.76 × AUC(Shoulder) +2.90 × AUC(Spine) − 7.66.
In Fig. 2, the mean AUC proprioception scores over the three joints that entered into the prediction equation for competition level – the ankle, shoulder and spine – are given, showing good separation between the competition level subgroups.
Proprioception underlies coordinated movement control,3–5 and the significant correlations between proprioceptive sensitivity and competition level observed in the present study indicate that proprioception tests may be useful in talent identification. For the sports tested here, ankle proprioceptive acuity was found to be the single best predictor for sport level achieved, predicting competition level achieved better than years of sport-specific training. This result suggests that research on the genetics of proprioceptive acuity is warranted, in addition to other factors currently considered as contributing to selection for high-level athlete success.26 Proprioceptive acuity over 5 joints for all sports groups studied was significantly better than for their non-athletic peers, a result consistent with previous research.3–5 Superior proprioceptive ability in athletes has been ascribed to their prolonged sport training.3,4,6 However, the present finding of no significant correlation between movement discrimination scores at any of the 5 joints tested and years of sport-specific training suggests that, while high level sport skills are associated with years of training,27 the mechanism for developing enhanced proprioceptive ability is different. Although studies have shown that proprioceptive acuity can be improved by a period of specifically designed training,7 Baker et al.28 suggested that the amount of improvement due to training is constrained by genetic factors. That the lack of association of proprioceptive acuity with years of sport-specific training may be more biologically determined, and therefore not readily trainable, has been suggested by Ashton-Miller.8 Thus different sports would tend to select those athletes with a sport-specific pattern of joint proprioceptive sensitivity, and within a sport, those athletes with the highest, most suited proprioceptive abilities would progress. It might be expected that in sports other than the five represented in the current work, different patterns of proprioceptive ability would contribute to success in sport competition. As found in previous work, the relationships observed here between the movement discrimination measures did not support the concept of a general proprioceptive ability common to a number of proprioception tests, but rather were consistent with the view that proprioceptive sensitivity is site-specific, since scores obtained from testing at one joint were not related to proprioception scores for other joints.14,29 While it remains unclear whether proprioceptive ability at different body sites is genetically determined or experience-dependent, the data reported here clearly show that superior proprioceptive ability is associated with achieving success in sport competition.
4. Discussion
5. Conclusion
Regression analysis of proprioceptive sensitivity data from elite athletes competing at 3 different levels in five different sports showed that the specific contributors to prediction of level of competitive success in these sports were proprioceptive sensitivity scores for the ankle, shoulder and spine, which, together with the number of years of sport-specific training, accounted for 30% of the variance in competition level achieved. These findings suggest that having good proprioceptive ability at the ankle, shoulder and spine is important for sporting success. Of the set, ankle proprioceptive ability emerged as the primary predictor. The ankle joint test conducted here involved ankle inversion movements, and the importance of ankle frontal plane proprioceptive measures to unipedal balance has been noted in recent work by Allet et al.24 The importance of frontal plane ankle proprioception has therefore been demonstrated across the performance spectrum. In addition to its association with a higher level of sport performance, having good ankle inversion proprioception has also been shown to be associated with a lower risk of ankle injury.25
The present study provides the first evidence of an association between proprioceptive sensitivity and achievement in elite sport. Ability to differentiate small differences between active movements at the ankle, shoulder and spine was found to be significantly related to the competition level achieved by elite athletes in aerobic gymnastics, swimming, sports dancing, badminton and soccer. While the importance of physical and mental preparation for success in sport at the international level is widely accepted and training aims to optimize these aspects, the current data suggest that proprioceptive ability is also an important determining attribute, and one which warrants further research.
6. Practical implications • For elite athletes in aerobic gymnastics, swimming, sports dancing, badminton and football, proprioceptive ability measured at the ankle, shoulder and spine is associated with the competition level that they have achieved.
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• Proprioceptive ability scores for tests at the ankle, knee, shoulder, spine and fingers do not correlate with years of sport-specific training, suggesting that proprioception is not improved as a byproduct of sports training. • The implication that proprioceptive ability is not a product of training suggests that tests to identify good proprioceptive ability could play a role in identifying talented athletes for participation in sport-specific training programs. Acknowledgements The authors would like to thank the University of Canberra and Shanghai Municipal Science and Technology Commission (Grant number 13490503800) for funding the research, and the Shanghai University of Sport for allowing recruitment of the athletes who took part. None of the authors have any relevant conflicts of interest. References 1. Goble DJ. Proprioceptive acuity assessment via joint position matching: from basic science to general practice. Phys Ther 2010; 90(8):1176–1184. 2. Gandevia SC, Refshauge KM, Collins DF. Proprioception: peripheral inputs and perceptual interactions, In: Sensorimotor control of movement and posture. US, Springer, 2002. 3. Lephart SM, Giraldo JL, Borsa PA et al. Knee joint proprioception: a comparison between female intercollegiate gymnasts and controls. Knee Surg Sports Traumatol Arthrosc 1996; 4(2):121–124. 4. Muaidi QI, Nicholson LL, Refshauge KM. Do elite athletes exhibit enhanced proprioceptive acuity, range and strength of knee rotation compared with nonathletes? Scand J Med Sci Sports 2009; 19(1):103–112. 5. Lin CH, Lien YH, Wang SF et al. Hip and knee proprioception in elite, amateur, and novice tennis players. Am J Phys Med Rehabil 2006; 85(3):216–221. 6. Aydin T, Yildiz Y, Yildiz C et al. Effects of extensive training on female teenage gymnasts’ active and passive ankle-joint position sense. J Sport Rehabil 2002; 11(1):1–10. 7. Daneshjoo A, Mokhtar AH, Rahnama N et al. The effects of comprehensive warmup programs on proprioception, static and dynamic balance on male soccer players. PLoS ONE 2012; 7(12):12. 8. Ashton-Miller JA, Wojtys EM, Huston LJ et al. Can proprioception really be improved by exercises? Knee Surg Sports Traumatol Arthrosc 2001; 9(3):128–136. 9. Waddington G, Shepherd R. Ankle injury in sports: role of motor control systems and implications for prevention and rehabilitation. Phys Ther Rev 1996; 1:79–87. 10. Witchalls JB, Newman P, Waddington G et al. Functional performance deficits associated with ligamentous instability at the ankle. J Sci Med Sport 2012; 16(2):89–93.
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11. Waddington G, Seward H, Wrigley T et al. Comparing wobble board and jumplanding training effects on knee and ankle movement discrimination. J Sci Med Sport 2000; 3(4):449–459. 12. Hobbs AJ, Adams RD, Shirley D et al. Comparison of lumbar proprioception as measured in unrestrained standing in individuals with disc replacement, with low back pain and without low back pain. J Orthop Sports Phys Ther 2010; 40(7):439–446. 13. Whiteley RJ, Adams RD, Nicholson LL et al. Shoulder proprioception is associated with humeral torsion in adolescent baseball players. Phys Ther Sport 2008; 9(4):177–184. 14. Han J, Anson J, Waddington G et al. Proprioceptive performance of bilateral upper and lower limb joints: side-general and site-specific effects. Exp Brain Res 2013; 226(3):313–323. 15. Han J, Waddington G, Adams R et al. Bimanual proprioceptive performance differs for right- and left-handed individuals. Neurosci Lett 2013; 542: 37–41. 16. Hong F, Wu P, Xiong H. Beijing ambitions: an analysis of the Chinese elite sports system and its Olympic strategy for the 2008 Olympic games. Int J Hist Sport 2005; 22(4):510–529. 17. Oldfield RC. The assessment and analysis of handedness: the Edinburgh inventory. Neuropsychologia 1971; 9(1):97–113. 18. Han J, Waddington G, Anson J et al. Does elastic resistance affect finger pinch discrimination? Hum Factors 2013; 55:976–984. 19. Waddington G, Adams RD. The effect of a 5-week wobble-board exercise intervention on ability to discriminate different degrees of ankle inversion, barefoot and wearing shoes: a study in healthy elderly. J Am Geriatr Soc 2004; 52(4):573–576. 20. Han J, Waddington G, Adams R et al. Ability to discriminate movements at multiple joints around the body: global or site-specific. Percept Mot Skills 2013; 116(1):59–68. 21. Ashton-Miller JA. Proprioceptive thresholds at the ankle: implications for the prevention of ligament injury, In: Proprioception and neuromuscular control in joint stability. Champaign, Human Kinetics Publ., 2000. 22. Swets JA. Signal detection theory and ROC analysis in psychology and diagnostics: collected papers, England, Lawrence Erlbaum Associates, 1996. 23. Tabachnick BG, Fidell LS. Using multivariate statistics, 5th ed. Needham Heights, Allyn & Bacon, 2006. 24. Allet L, Kim H, Ashton-Miller J et al. Frontal plane hip and ankle sensorimotor function, not age, predicts unipedal stance time. Muscle Nerve 2012; 45(4):578–585. 25. Witchalls J, Blanch P, Waddington G et al. Intrinsic functional deficits associated with increased risk of ankle injuries: a systematic review with meta-analysis. Br J Sports Med 2012; 46(7):515–523. 26. Davids K, Baker J. Genes environment and sport performance: why the nature–nurture dualism is no longer relevant. Sports Med 2007; 37(11):961–980. 27. Ericsson KA. The Cambridge handbook of expertise and expert performance, London, Cambridge University Press, 2006. 28. Baker J, Horton S, Robertson-Wilson J et al. Nurturing sport expertise: factors influencing the development of elite athlete. J Sports Sci Med 2003; 2(1): 1–9. 29. Waddington G, Adams R. Discrimination of active plantarflexion and inversion movements after ankle injury. Aust J Physiother 1999; 45(1):7–13.
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G Model JSAMS-975; No. of Pages 5
Journal of Science and Medicine in Sport xxx (2013) xxx–xxx
Contents lists available at ScienceDirect
Journal of Science and Medicine in Sport journal homepage: www.elsevier.com/locate/jsams
Original research
Level of competitive success achieved by elite athletes and multi-joint proprioceptive ability Jia Han a,b,∗ , Gordon Waddington b , Judith Anson b , Roger Adams c a b c
Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, China Faculty of Health, University of Canberra, Australia Faculty of Health Sciences, University of Sydney, Australia
a r t i c l e
i n f o
Article history: Received 25 July 2013 Received in revised form 8 November 2013 Accepted 28 November 2013 Available online xxx Keywords: Proprioception Movement discrimination Elite athletes Performance Training
a b s t r a c t Objectives: Proprioceptive ability has been suggested to underpin elite sports performance. Accordingly, this study examined the relationship between an athlete’s proprioceptive ability, competition level achieved, and years of sport-specific training. Design: Cross-sectional study. Methods: One hundred elite athletes, at competition levels ranging from regional to international, in aerobic gymnastics, swimming, sports dancing, badminton and soccer, were assessed for proprioceptive acuity at the ankle, knee, spine, shoulder, and finger joints. An active movement extent discrimination test was conducted at each joint, to measure ability to discriminate small differences in movements made to physical stops. Results: Multiple regression analysis showed that 30% of the variance in the sport competition level an athlete achieved could be accounted for by an equation that included: ankle movement discrimination score, years of sport-specific training, and shoulder and spinal movement discrimination scores (p < 0.001). Mean proprioceptive acuity score over these three predictor joints was significantly correlated with sport competition level achieved (r = 0.48, p < 0.001), highlighting the importance of proprioceptive ability in underpinning elite sports performance. Years of sport-specific training correlated with an athlete’s sport competition level achieved (r = 0.29, p = 0.004), however, proprioceptive acuity was not correlated with years of sport-specific training, whether averaged over joints or considered singly for each joint tested (all r ≤ 0.13, p ≥ 0.217). Conclusions: Proprioceptive acuity is significantly associated with the performance level achieved by sports elites. The amount of improvement in proprioceptive acuity associated with sport-specific training may be constrained by biologically determined factors. © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
1. Introduction Proprioceptive sensitivity is the ability to integrate sensory information from mechanoreceptors and thereby determine body position and movements in space.1,2 Having good proprioceptive ability is more important for tasks with high skill demand than it is for normal activities,3–5 suggesting that it may underlie elite athletic performance. However, there is presently little evidence to support this hypothesis. Although some research has shown athletes to have superior proprioceptive ability compared to non-athletic controls,3–5 the tests have been conducted at one joint, and in one sport. As a consequence, it has not been determined whether proprioceptive ability determined over multiple body joints, for athletes in
∗ Corresponding author. E-mail addresses: [email protected], [email protected] (J. Han).
different sports, is related to how good an athlete is, as reflected in the competition level they have achieved. Superior proprioceptive ability in athletes has been attributed to prolonged periods of athletic training.3,4,6 Because few studies have examined the relationship between proprioceptive ability and years of sport-specific training, it is not known whether this superior proprioceptive ability in athletes is inherently determined and selected for by competitive success, or whether it arises from extensive training. Recently, Daneshjoo et al.7 reported that knee proprioception at 45 and 60◦ was significantly improved by eight weeks of specifically designed warm up program, suggesting that proprioception may be enhanced by sport-specific training. If enhanced proprioceptive ability is an outcome of years of sport-specific training, proprioceptive sensitivity and years of sport-specific training should be significantly correlated. Conversely, it has been argued that proprioception cannot be trained,8 suggesting that no correlation would be apparent.
1440-2440/$ – see front matter © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jsams.2013.11.013
Please cite this article in press as: Han J, et al. Level of competitive success achieved by elite athletes and multi-joint proprioceptive ability. J Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2013.11.013
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2 Table 1 Participant information.
Elite competition level (n)
Aerobic gymnastics (8 M, 12 F) Swimming (10 M, 10 F) Sports dancing (7 M, 13 F) Badminton (12 M, 8 F) Football (Soccer) (13 M, 7 F) Control group (10 M, 10 F)
Sport-specific training (years)
Body mass (kg)
Height (m)
i
ii
iii
Mean
Range
Mean
Range
Mean
4 4 10 7 14 –
10 11 7 11 4 –
6 5 3 2 2 –
6 14 5 9 10 –
3–13 6–15 2–16 4–12 6–13 –
60 70 53 66 67 61
48–75 56–92 45–75 57–76 52–85 51–83
1.69 1.77 1.67 1.77 1.74 1.71
Age (years)
Range 1.58–1.78 1.66–1.92 1.56–1.80 1.64–1.86 1.61–1.90 1.63–1.82
Mean
Range
21 20 20 20 21 21
18–23 19–22 18–23 18–22 20–22 20–22
For elite competition level, i represents Chinese national top 32 or regional top 3; ii represents Chinese national top 16; and iii represents Chinese national top 6 and competing internationally.
The aim of the current study was to examine the relationship between proprioceptive ability, competition level achieved, and years of sport-specific training. Elite athletes from 5 sports – aerobic gymnastics, swimming, sports dancing, badminton, and soccer – all actively competing at regional, national or international level, were recruited, and proprioception tests conducted on 5 body sites: the ankle, knee, spine, shoulder and fingers. In the present study, a set of tests, each using a form of the active movement extent discrimination apparatus (AMEDA), was employed to assess proprioceptive ability. The AMEDAs were developed based on the principle of replicating functional movement,9 i.e., using active rather than passive movement, testing in normal weight-bearing conditions, moving at a steady pace, and without physical constraints to non-tested limbs, in order to maximize the ecological validity of proprioception testing. The AMEDA method for assessing proprioceptive acuity has been validated by being able to: identify subjects with ankle ligament laxity,10 evaluate the effect of training on knee proprioception,11 show different patterns of spine flexion discrimination in subjects with spinal disc replacement,12 reveal a correlation between shoulder proprioception with humeral torsion in adolescent baseball players13 and show superiority for the non-dominant hand/hemisphere system in the utilization of pinch movement proprioception.14,15 2. Methods The project was approved by the University of Canberra Committee for Ethics in Human Research (approval number: CEHR 11-47) and written informed consent was obtained from participants before testing sessions commenced. The organizations that provided funding for this project had no role in recruitment, data collection, analysis, interpretation, or approval for submission for publication. Participant information is presented in Table 1. Recruitment was from sports where there were sufficient elite athletes available at the time of testing. One hundred right-handed athletes competing at high levels in five different sports and twenty right-handed, non-athletic controls were recruited from advertisements posted throughout the Shanghai University of Sport. The athletes who volunteered had a minimum of two years of sport-specific training, and all were actively competing in their chosen sport. An athlete’s sport competition level was determined as their best level achieved within the prior year, at three elite levels. These were, from lowest to highest: (i) Chinese national top 32 or regional top 3; (ii) Chinese national top 16; and (iii) Chinese national top 6 and competing internationally. Given the selection pool for athletes in China, all individuals reaching these levels can be regarded as elites.16 A group of healthy university students without any history of specialized training experience specific to a particular sport was recruited as non-athletic controls. As all students participated in the weekly 90 min physical education classes held at the Shanghai University of Sport, they were physically able to undertake the proprioception
tests. All participants were asked to adhere to their normal routine of training, sleeping, eating and hydration prior to doing the AMEDA tests. The Edinburgh Handedness Inventory17 was used to determine right-handedness. When questioned regarding footedness, all participants responded that they would also use their right foot to kick a ball. A health questionnaire was used to rule out the presence of significant injuries within the past 6 months or a diagnosis of neurological disease, specifically Parkinson’s disease, brain damage, chronic pain, Down’s syndrome or diabetic neuropathy.3 A purpose-built AMEDA was employed for the proprioception tests at each body site (Fig. 1). The apparatus employed here has been described previously for the ankle,10 the knee,11 the spine,12 the shoulder13 and the fingers.18 Reliability of the scores (Interclass Correlation Coefficient) generated by the AMEDA tests has been determined as ranging from 0.82 to 0.96.14,18,19 The series of AMEDAs were used to generate a set of 5 end positions at each joint tested. The 5 predetermined displacements from smallest to largest were: ankle inversion = 10, 11, 12, 13 and 14◦ , knee flexion = 37, 38, 39, 40 and 41◦ , spine flexion = 20.9, 21.5, 22.1, 22.6 and 23.2◦ , shoulder flexion = 170.6, 171.2, 171.7, 172.3 and 172.9◦ , and thumb-index finger pinch extent = 5.5, 8.0, 10.5, 13.0 and 15.5 mm. A position number (1, 2, 3, 4 or 5) was assigned to each movement displacement in order, so that participants were able to use the assigned position numbers to make their responses during the test. The protocol for testing at each joint consists of a standardized familiarization session and a data collection session. During the familiarization session before data collection, each participant was informed that they would experience the five movement distances in order, from the smallest (moving to position 1) to the largest (moving to position 5), three times in succession, to ensure participants were focused on the relevant dimension. After the 15-trial familiarization, participants then undertook 50-trials of testing, in which all five positions were presented 10 times, in a random order. During testing, participants were asked to make a judgment as to the position number (1, 2, 3, 4 or 5) of each movement as soon as they returned the testing joint to the start position, without feedback being given regarding the correctness to the judgment they made for each trial. That is, the participants used their memory of the 5 movement displacements from the familiarization trials to enable them to evaluate the current stimulus and thus make a numerical judgment about each stimulus as it was presented. This task was thus a single stimulus, or absolute judgment task, wherein a single stimulus was presented and single response was made on each trial. The psychophysical method employed in the current study fulfills the validity criteria for assessing active movement function, with sufficient trials to determine participants’ ability to use proprioceptive information when they discriminate a set of movements.20,21 The procedure for spine flexion discrimination is described here as an example. Participants wore a loose shirt, short pants and were
Please cite this article in press as: Han J, et al. Level of competitive success achieved by elite athletes and multi-joint proprioceptive ability. J Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2013.11.013
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Fig. 1. Active movement extent discrimination apparatus for testing proprioception at the 5 body sites: a, spine flexion; b, shoulder flexion; c, knee flexion; d, ankle inversion; and e, finger pinch.
barefoot. They stood facing the height-adjustable spine AMEDA with their big toes aligned with a tape marker, to maintain the same original testing position for each participant. For each trial of the spine AMEDA test, participants made an active spine flexion movement at a steady pace, starting from the neutral standing position with the fixed stop against their thoracic spine, and moved their trunk forward until their sternum touched the stepper motor knob. Participants were unable to see the stepper motor knob at any time throughout the movement. After returning to the upright position at the same pace, participants identified the extent of spine flexion they had just experienced, out of five possible distances. The similar procedures for AMEDA testing of active movements of ankle inversion, knee flexion, shoulder flexion and finger pinch discrimination have been described previously.14 The testing order of the different joints on the dominant right side, and at the spine, was randomized for each participant. Participants were allowed to have a short break between joint sites to avoid fatigue. The complete test at each body site, with 15 familiarization trials and 50 test trials, took 10 min, and completing all 5 movement discrimination tasks required approximately 1 h. To obtain an accuracy metric, non-parametric signal detection analysis was used to produce pair-wise Receiver Operating Characteristic (ROC) curves. Stimulus–response matrices were constructed, with cell entries representing the frequency with which each response was made for each stimulus. Discrimination sensitivity between adjacent positions was calculated in a pair-wise fashion (i.e., 1–2, 2–3, 3–4, 4–5). Thereafter, the mean pair-wise Area Under the Curve (AUC) value was calculated using SPSS software V.18, to give each participant a single discrimination sensitivity score at a particular joint. The AUC score, derived from the ROC curve, provides an unbiased estimate of the ability of an individual to discriminate between the five different stimuli.22 AUC values range from 0.5, which is equivalent to chance responding, to 1.0, representing perfect ability to discriminate between the 5 different movement extents. Scores were obtained from the AMEDA tests of proprioceptive sensitivity at the ankle, knee, shoulder, spine and fingers for the 20 participants in each of the sports groups, and for the 20 non-athletic controls, and the means and 95% confidence intervals (CIs) were calculated for each of the groups. Thereafter, scores were entered into a repeated-measures ANOVA, with planned contrasts used to compare each of the five sport groups with the non-athlete control group. Where the Mauchly Sphericity Test result was significant, the Greenhouse–Geisser corrected F-value was used.
Pearson correlations were calculated to assess the relationship between movement discrimination scores of each of the five body sites and sports competition level, years of sport-specific training, age, height and body mass. The sample size of 100 in the present study fulfilled the minimum sample size requirement for linear regression (n ≥ 50 + 8 × m, where m = 6 independent variables: the movement discrimination scores at the ankle, knee, spine, shoulder and fingers, and years of sport-specific training).23 Accordingly, step-wise multiple regression analysis was conducted, with competition level as the dependent variable and AUC proprioception sensitivity scores at the ankle, knee, shoulder, spine, and finger, and years of sportspecific training entered as independent variables. 3. Results The mean and the upper and lower bounds of the 95% CIs for the AUC proprioceptive acuity score of each sport group were: aerobic gymnastics 0.680 (0.670–0.690), swimming 0.662 (0.652–0.672), sports dancing 0.667 (0.657–0.677), badminton 0.666 (0.656–0.676) and soccer 0.674 (0.664–0.684). The mean and the 95% CI for the non-athletic control group were 0.641 (0.631–0.651). Mean AUC across 5 joints for athletes in every sport was significantly greater than for the non-athletic control group, with the p-values for comparisons with aerobic gymnastics, swimming, sports dancing, badminton and soccer being 0.001, 0.003, 0.001, 0.001 and 0.001, respectively. Correlation values showed that sport competition level was significantly correlated with ankle (r = 0.43, p < 0.001) and shoulder proprioceptive acuity scores (r = 0.24, p = 0.015), but not with proprioceptive acuity at the spine (r = 0.15, p = 0.149), knee (r = −0.02, p = 0.866) or fingers (r = −0.09, p = 0.369). There was no significant relationship between years of sport-specific training and proprioceptive acuity score for any of the joints tested (all r ≤ 0.13, p ≥ 0.217), however, years of sport-specific training was significantly correlated with sport competition level (r = 0.29, p = 0.004), suggesting that while sport skill improves with years of training, proprioceptive acuity does not. The lack of significant correlations in the observed pattern of relationships between the proprioception scores for different joints (all r ≤ 0.12, p ≥ 0.219) further supports the notion of proprioception as joint-specific, rather than proprioceptive acuity being a global attribute.20 Multiple regression was used to determine whether an athlete’s years of training and joint proprioceptive acuity scores could
Please cite this article in press as: Han J, et al. Level of competitive success achieved by elite athletes and multi-joint proprioceptive ability. J Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2013.11.013
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Fig. 2. Mean proprioceptive acuity scores from the ankle, shoulder and spine active movement extent discrimination tasks, for the three competition level subgroups within each of the five sports. Being at a higher competition level was associated with better proprioceptive acuity, measured as averaged Area Under the Curve (AUC) scores over the three joints. Scores from the highest level athletes, Chinese national top 6 and competing internationally are represented by filled triangle symbols, Chinese national top 16 by filled circles, and for the Chinese national top 32 or regional top 3, filled squares are used.
predict their competition level. A significant prediction equation was found (F4,95 = 11.5, p < 0.001) that accounted for 30% of the variance in competition level (adjusted R2 = 0.30). The model produced four predictors that added significant independent amounts to the total variance that could be accounted for in sport competition level. The predictor variables were ankle proprioception AUC score (18%), years of sport-specific training (6%), shoulder proprioception AUC score (4%) and spine proprioception AUC score (2%). The resulting equation was: Predicted Sport Competition Level = 6.12 × AUC(Ankle) + 0.05 × Years of sport-specific training + 4.76 × AUC(Shoulder) +2.90 × AUC(Spine) − 7.66.
In Fig. 2, the mean AUC proprioception scores over the three joints that entered into the prediction equation for competition level – the ankle, shoulder and spine – are given, showing good separation between the competition level subgroups.
Proprioception underlies coordinated movement control,3–5 and the significant correlations between proprioceptive sensitivity and competition level observed in the present study indicate that proprioception tests may be useful in talent identification. For the sports tested here, ankle proprioceptive acuity was found to be the single best predictor for sport level achieved, predicting competition level achieved better than years of sport-specific training. This result suggests that research on the genetics of proprioceptive acuity is warranted, in addition to other factors currently considered as contributing to selection for high-level athlete success.26 Proprioceptive acuity over 5 joints for all sports groups studied was significantly better than for their non-athletic peers, a result consistent with previous research.3–5 Superior proprioceptive ability in athletes has been ascribed to their prolonged sport training.3,4,6 However, the present finding of no significant correlation between movement discrimination scores at any of the 5 joints tested and years of sport-specific training suggests that, while high level sport skills are associated with years of training,27 the mechanism for developing enhanced proprioceptive ability is different. Although studies have shown that proprioceptive acuity can be improved by a period of specifically designed training,7 Baker et al.28 suggested that the amount of improvement due to training is constrained by genetic factors. That the lack of association of proprioceptive acuity with years of sport-specific training may be more biologically determined, and therefore not readily trainable, has been suggested by Ashton-Miller.8 Thus different sports would tend to select those athletes with a sport-specific pattern of joint proprioceptive sensitivity, and within a sport, those athletes with the highest, most suited proprioceptive abilities would progress. It might be expected that in sports other than the five represented in the current work, different patterns of proprioceptive ability would contribute to success in sport competition. As found in previous work, the relationships observed here between the movement discrimination measures did not support the concept of a general proprioceptive ability common to a number of proprioception tests, but rather were consistent with the view that proprioceptive sensitivity is site-specific, since scores obtained from testing at one joint were not related to proprioception scores for other joints.14,29 While it remains unclear whether proprioceptive ability at different body sites is genetically determined or experience-dependent, the data reported here clearly show that superior proprioceptive ability is associated with achieving success in sport competition.
4. Discussion
5. Conclusion
Regression analysis of proprioceptive sensitivity data from elite athletes competing at 3 different levels in five different sports showed that the specific contributors to prediction of level of competitive success in these sports were proprioceptive sensitivity scores for the ankle, shoulder and spine, which, together with the number of years of sport-specific training, accounted for 30% of the variance in competition level achieved. These findings suggest that having good proprioceptive ability at the ankle, shoulder and spine is important for sporting success. Of the set, ankle proprioceptive ability emerged as the primary predictor. The ankle joint test conducted here involved ankle inversion movements, and the importance of ankle frontal plane proprioceptive measures to unipedal balance has been noted in recent work by Allet et al.24 The importance of frontal plane ankle proprioception has therefore been demonstrated across the performance spectrum. In addition to its association with a higher level of sport performance, having good ankle inversion proprioception has also been shown to be associated with a lower risk of ankle injury.25
The present study provides the first evidence of an association between proprioceptive sensitivity and achievement in elite sport. Ability to differentiate small differences between active movements at the ankle, shoulder and spine was found to be significantly related to the competition level achieved by elite athletes in aerobic gymnastics, swimming, sports dancing, badminton and soccer. While the importance of physical and mental preparation for success in sport at the international level is widely accepted and training aims to optimize these aspects, the current data suggest that proprioceptive ability is also an important determining attribute, and one which warrants further research.
6. Practical implications • For elite athletes in aerobic gymnastics, swimming, sports dancing, badminton and football, proprioceptive ability measured at the ankle, shoulder and spine is associated with the competition level that they have achieved.
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