- Email: [email protected]
Non-specific low back pain in male professional football players in the Turkish super league
Science & Sports (2013) 28, e93—e98
Disponible en ligne sur
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ORIGINAL ARTICLE
Non-specific low back pain in male professional football players in the Turkish super league Lombalgies non spécifiques chez les footballeurs professionnels turcs A. C ¸ali , N. Gelecek , S.S. Subasi ∗ School of Physical Therapy and Rehabilitation, Dokuz Eylül University, Inciralti 35340 Izmir, Turkey Received 2 November 2011; accepted 2 August 2012 Available online 23 January 2013
KEYWORDS Low back pain; Professional; Football; Male
MOTS CLÉS Douleur lombaire ; Professionnel ; Football ; Male
∗
Summary Objectives. — The aim of this study was to determine the prevalence and possible causes of non-specific low back pain (LBP) in male professional football players in the Turkish Super League. Methods. — A total of 121 players were questioned for demographic variables and whether they have had LBP in the last year. Player position, training characteristics, number of years as a football player, injury background and last season statistics were investigated. Flexibility of low back and hamstring muscles, and hamstring muscle length were measured. Results. — Thirty-eight football players reported non-specific LBP in last year with a prevalence of 31.4%. It was found that more matches played in a starting position and hamstring muscle shortness were significant factors for developing non-specific LBP (P < 0.05). Conclusion. — The prevalence of non-specific LBP in Turkish male professional football players is 31.4%, similar to the literature findings. Hamstring muscle shortness and high numbers of matches played as a starter are important factors for non-specific LBP. These findings should be considered for injury prevention. Causes of LBP in football players require further investigation. Studies should be performed on a larger sample of participants to attain more certain results. © 2013 Published by Elsevier Masson SAS. Résumé Objectifs. — Le but de cette étude était de déterminer la prévalence et les causes possibles de lombalgies aspécifiques chez les footballeurs professionnels masculins. Méthodes. — Les caractéristiques démographiques et la fréquence de survenue des lombalgies ont été évaluées par questionnaires chez 121 footballeurs. Les données relatives à la position du joueur, les caractéristiques de son entraînement, le nombre d’années de pratique du football, les blessures encourues dans le passé ont été recueillies. La flexibilité des muscles de la région
Corresponding author. E-mail addresses: [email protected], [email protected] (S.S. Subasi).
0765-1597/$ – see front matter © 2013 Published by Elsevier Masson SAS. http://dx.doi.org/10.1016/j.scispo.2012.08.003
e94
A. C ¸ ali et al. lombaire et des ischio-jambiers, ainsi que la longueur des muscles ischio-jambiers ont été évaluées. Résultats. — Trente-huit footballeurs ont mentionné avoir eu des lombalgies aspécifiques dans l’année qui précédait, avec une prévalence de 31,4 %. Deux facteurs de risque de survenue de lombalgie ont été retenus, l’augmentation du nombre de matchs joués pour les avants-centres et le fait d’avoir des muscles ischio-jambiers courts (p < 0,05). Conclusion. — La prévalence de lombalgies aspécifiques chez des footballeurs professionnels masculins est de 31,4 % ; cette valeur est similaire aux résultats rapportés dans la littérature. Le fait d’avoir des muscles ischio-jambiers courts et l’augmentation du nombre de matchs joués en position d’avant-centre sont des facteurs de risque de survenue de lombalgies. Ces résultats devraient être considérés pour la prévention d’accidents. Les causes des douleurs lombaires chez les footballeurs demandent des études supplémentaires, en incluant des échantillons plus importants de footballeurs. © 2013 Publié par Elsevier Masson SAS.
1. Introduction Football is one of the most popular sports worldwide [1,2]. Football requires the player to have appreciable stamina while superimposing sprinting, kicking, jumping, tackling, sudden changes of direction, and defense. It also involves a combination of repetitive, high-intensity activities [3,4]. Some researchers reported that the overall injury risk was higher in male professional football player than in industrial occupations [5,6]. It is known that lower extremity and head injuries are common among football players [7]. Furthermore, non-specific low back pain (LBP) has been documented longitudinally for the last two decades in athletes [8—10]. LBP is estimated to have yearly prevalence of 15% to 20% and a lifetime prevalence of 50% to 80% in general adult population [11]. Studies reported that rates of LBP in athletes range from 1% to 30% and are affected by the type of sport, age, gender, technique, and intensity of training [12,13]. Recently, professional football players and football players have experienced LBP more severely and frequently than non-athletic controls, particularly in the male population [14,15]. The football player carries a significant risk for acute and overuse injuries in the low back region due to excessive working of muscles in trunk, which over time, can lead to spinal mechanical overload [16]. During football game activities, neuromuscular control of the trunk is important. Trunk muscles provide adequate force to maintain normative lumbar lordosis and to stabilize and protect the vertebral column from injuries in both static and dynamic condition [15,17]. The asymmetrical changes, and ballistic tasks that involve trunk rotation and flexion in a football game are accepted as risk factors for the trunk and low back injuries due to overload on the vertebral column [15,18]. Recently, football has become more competitive requiring players to perform at a higher level, which can lead the player to repeated eccentric and concentric overload in low back region and consequently LBP problems [3,18,19]. Therefore, the back and low back regions have recently been investigated in research studies designed for classifying these injuries among football players [3,19]. Although LBP rates rise in football, there is a lack of studies specifically investigating non-specific LBP in male professional football players. For this reason, the aims of
the present study were to determine the prevalence of nonspecific LBP and to investigate the possible reasons of LBP in male professional league football players.
2. Methods 2.1. Participants The Super league is at the top of the Turkish professional football league and is the country’s primary football competition. A total of 121 male professional football players from the Turkish Super League were included in this study with a mean age of 23.8 ± 4.1 years (mean ± SD) ranged from 16 to 34 years. Study protocol was approved by the Ethics Committee of Dokuz Eylul University (case 03.07.2008/304) and performed in accordance with the ethical standards set by the 1964 Declaration of Helsinki. An informed consent form was taken from all participants at the beginning of the study after all participants’ questions were answered.
2.2. Procedures There are 18 professional football clubs in the Turkish Super League. At the beginning of the study, a letter was sent to the administrative staffs of the clubs detailing the study’s aim and test procedures. Eleven of 18 clubs refused to participate, because they will be gone out of Turkey for new season training. The rest of the clubs accepted to participate. Consequently, the study was completed with 121 professional football players. All measurements were performed at team specific locations by the same physiotherapist. Inclusion criteria for this study were active participation for the last two seasons on a professional football team and having no neurological deficit due to LBP. Exclusion criteria were the presence of lumbar intervertebral disc pathologies or past low back surgery. The anthropometric characteristics and pain existence (yes or no) were collected from their medical records and player charts. Pain characteristics and pain related functional limitations in last year were questioned. Current pain intensity, average pain intensity in last year, avoidance of performing activities of daily
Non-specific low back pain in professional soccers living (ADL), avoidance of social and family relationships and restriction of playing football according to visual analog scale (VAS) were recorded and number of off days due to pain in last year was noted. Playing positions of the participants were recorded as goalkeeper, defender, midfielder and forward. Injury history during their football careers and localizations were determined. Injury sites were divided into groups according to their frequency as: ankle/foot; knee/calf; hip/thigh; head/neck; and upper extremity. Participants were questioned for the factors that may contribute to LBP. The questions are presented below: • active years in football (amateur, professional and total); • information about last season (daily training duration [minutes], weekly training frequency [days], number of matches played last season and number of matches played last season in a starting position) [20—22]. The ‘‘Passive Straight Leg Test’’ was used for to measure hamstring length [23]. Participants were placed in supine position, lying on a pillow that supported their lumbar lordosis. A universal goniometer was used. The goniometer was placed on the trochanter major of the femur. The examiner passively flexed the hip joint while the knee was fully extended. The angle was recorded when firm resistance was detected in the hamstring muscle group or when the player wanted to stop. This procedure was repeated three times for each lower extremity and an average of all three consecutive measures was recorded. The ‘‘Sit and Reach Flexibility Test’’ was used to measure the flexibility of the low back and hamstring muscles. Assessment of tightness in this area is important due to its implication in lumbar lordosis, forward pelvic tilt, and LBP. The participant sits on the floor, legs fully extended, with the soles of their feet pressed against the sit and reach box. The participant then bends forward and reaches their fingertips as far as possible. This test was repeated three times and the average of all three consecutive measures was recorded [24].
2.3. Statistical analyses The data obtained from these measurements were analyzed with the SPSS Windows (15.0) software package. All variables were normally distributed. Therefore, results are presented as mean ± standard deviations and percentages. Descriptive statistics were used to report player characteristics, pain and functional limitations. The samples were divided into two groups of players with and without non-specific LBP. Association between non-specific LBP, demographics, and possible risk factors were analyzed using Chi2 measures. Chi2 measures were directly used for the categorical variables. Median values were calculated to categorize all the continuous variables and then Chi2 measures were applied. The level of significance was set at P = 0.05.
3. Results Mean age, height, weight, and body mass index (BMI) of 121 male professional football players are illustrated in Table 1.
e95 Table 1 players.
Anthropometric characteristics of the football Mean ± SD
Age (year) Height (cm) Weight (kg) BMI (kg/m2 )
23.8 1.8 74.4 22.8
± ± ± ±
4.1 0.1 6.3 1.2
Min—max 16—34 1.6—1.9 55—96 19.8—26.3
Min-max: minimum-maximum; SD: standard deviation.
Thirty-eight players were considered to suffer from non-specific LBP, corresponding to a prevalence of 31.4%. Average pain intensity in last year was 4.87 ± 2.14 (mean ± SD) according to VAS. Seventeen participants (44.7%) reported their pain intensity as between 1 and 4 whereas 21 participants (55.3%) reported it as between 5 and 8 according to VAS. Thirty-one players reported no current pain (81.6%). Four participants (10.5%) reported their current pain intensity as between 1 and 4 whereas three participants (7.9%) reported it as between 5 and 6. Two participants’ (5.3%) avoidance of performing ADL were over 5 (6 and 9), four participants’ (10.5%) avoidance of performing ADL were between 1 and 2. Five participants’ (13.2%) restriction of social and family relationships were between 1 and 4, 2 participants’ (5.3%) restriction of social and family relationships were 6 and 8. Furthermore, 13 participants (34.2%) reported no restriction of playing football, 22 participants (57.9%) reported their restriction between 1 and 4, three participants (7.9%) reported it between 5 and 6. Only one participant with pain intensity of 3 (2.6%) was off for 2 days, whereas five participants with the pain intensity over 5 (13.2%) were off for more numbers of days between 3 to 10 days. Association between the demographics such as age, height, body weight, and BMI with non-specific LBP was not significant (P > 0.05) (Table 2). Total active football years of the players ranged from 5 to 27 years. When the relationship of amateur, professional, and total active years of football and non-specific LBP were investigated, no significant relationship was found (P > 0.05) (Table 2). Ankle and foot injuries (56.2%) were found at higher rates compared to the injuries in the other body parts in football players, as we expected. Other injury rates were determined as knee/calf (38%), hip/thigh (35.5%), upper extremity (14.9%), and head/neck (3.3%). Injury history and non-specific LBP were not significantly correlated (P > 0.05) (Table 2). Analysis of the previous season’s statistics revealed that the weekly training frequency of all the participants was 6 days, with a daily training duration of 90 minutes. The relationship between weekly training frequency, daily training duration and LBP was therefore not analyzed due to lack of variability. There was no association between the number of matches played last season and non-specific LBP (P > 0.05), whereas the number of matches played last season in a starting position was found to be related with non-specific LBP (P < 0.05) (Table 2). It was determined that playing over 20 matches in a starting position in one season was significantly related with non-specific LBP (P < 0.05) (Table 2).
e96
A. C ¸ ali et al.
Table 2 Association between possible risk factors and nonspecific low back pain (LBP). LBP (n) Demographics Age (years) ≤ 24 > 24 Height (cm) ≤ 180 > 180 Body weight (kg) ≤ 74 > 74 BMI (kg/m2 ) ≤ 22.7 > 22.7 Active years in football Amateur (years) ≤ 14 > 14 Profesionnal (years) ≤5 >5 Total (years) ≤ 14 > 14 Injury history Ankle & foot Yes (n) No (n) Knee and calf Yes (n) No (n) Hip and thigh Yes (n) No (n) Head and neck Yes (n) No (n) Upper extremity Yes (n) No (n) Last year statistics Numbers of matchesa ≤ 25 > 25 Starting positionb ≤ 20 > 20 Flexibility Hamstring shortness (R) ≤ 76◦ > 76◦ Hamstring shortness (L) ≤ 78◦ > 78◦ Sit and reach (cm) ≤6 >6
No LBP (n)
Table 3 Playing positions of the participants and nonspecific low back pain (LBP).
P
LBP
No LBP
Total
n
%
n
%
n
%
4 9 19 6
33.3 26.4 36.5 24
8 25 33 17
66.7 73.6 63.5 76
12 34 52 23
100 100 100 100
18 20
50 33
0.24
19 19
47 36
0.56
18 20
47 36
0.43
16 22
44 39
0.33
22 16
42 41
0.56
16 22
45 38
0.24
4. Discussion
22 16
49 34
1.00
15 (39.5%) 23 (60.5%)
53 (63.8%) 30 (36.2%)
0.30
13 (34.2%) 25 (65.8%)
33 (39.7%) 50 (60.3%)
0.69
16 (42.1%) 22 (57.9%)
27 (32.5%) 56 (67.5%)
0.31
3 (7.9%) 35 (92.1%)
1 (1.2%) 82 (98.8%)
0.91
5 (13.1%) 33 (86.9%)
13 (15.7%) 70 (84.3%)
0.79
16 22
46 37
0.24
14 24
47 36
0.04
25 13
36 47
0.03
26 12
49 34
0.04
24 14
41 42
0.17
We aimed to determine the prevalence of non-specific LBP and to investigate the reasons leading to non-specific LBP in male professional football players in the Turkish Super League. We found that the prevalence of non-specific LBP was 31.4%. Results of the present study showed that lack of flexibility in the hamstring muscles and the numbers of matches played in a starting position were significant predictors of non-specific LBP in male professional football players. Research performed in last decade reports a rate of low back problems in athletes between 1% and 30% [12,25,26]. Although the incidences vary according to the type of sport, the research was mostly conducted with fewer participants, which makes it difficult to interpret the results [12,13,17]. Sward et al. found 79% LBP in 24 elite gymnasts in their study [27], while Kujala et al. reported this percentage as 46% in adolescent athletes [28]. Lundin et al. found 37% LBP in football players while tennis players displayed 32% [29]. Yet, there is a lack of information for the prevalence of LBP in male professional football players. Non-specific LBP prevalence of male professional football players in the Turkish Super League was determined as 31.4% in our study. It can be said that the average pain intensity of those football players in a year was found as moderate and 55.3% of the players suffered pain with the intensity of 5 to 8 according to VAS. Although a few of the players (15.8%) were off for a period between 2 days to 10 days due to LBP and it seems that most of the football players could work even though they had pain, our results revealed an important point that was the restriction of playing football with the rate of 65.8%. They mostly haven’t avoided performing ADL and haven’t avoided from social and family relationships. The position and responsibilities of the players are different in a football team, even though each position consists of similar motions and acts. These differences may cause differences in injury rates and locations as well. Hawkins and Fuller reported that the risk of injury is higher in defenders than players in other positions, due to increased player
Chi2 analyses, P < 0.05; BMI: body mass index. a Numbers of matches played (number/season). b Numbers of matches played as a starter (number/season).
Goalkeeper Defender Midfielder Forward
Flexibility of low back and hamstring muscles was not related with non-specific LBP (P > 0.05), whereas hamstring muscle shortness for both dominant and non-dominant sides was significantly related with non-specific LBP (P < 0.05) (Table 2). Chi2 analyses revealed that there was no correlation between the playing positions of the participants and nonspecific LBP (P = 0.72) (Table 3).
Non-specific low back pain in professional soccers contact [21]. In our study, we found no relationship between player positions and non-specific LBP. The research is inconsistent regarding the relationship between heavy physical work, age, and LBP. Researchers found that heavy physical work may be a factor contributing to LBP [30], whereas other research indicates that working conditions do not cause LBP [18,28,31]. Kovec et al. highlighted that the risk of injury was higher in men who have jobs that require heavy and repetitive motions, and work more than 8 hours a day [30]. Van Nieuwenhuyse et al., instead, stated that physical load was not a factor for developing LBP in young individuals [31]. Parameters related with physical load such as the numbers of matches played, and the numbers of matches played in a starting position in a season were investigated. It was found that players who played more matches in a starting position in a season had more LBP. We may speculate that the players might have more micro and/or macro trauma as they play in more matches in a starting position. Additionally, we thought that playing football for a longer time might lead to heavy and repetitive work on low back region. However, in our study we found that amateur, professional, and total active years in football are not factors for developing non-specific LBP. Football naturally includes long and heavy training. Players are not only injured during games but are also injured in training sessions during season and off-season trainings. Injury history is considered as a risk factor for new injuries [5]. Injury might cause lack of flexibility at the involved anatomical location and muscle and/or joint injuries of lower extremity might trigger abnormal body mechanics, therefore low back problems. Hawkins et al. highlighted that ankle injuries deteriorate ankle biomechanics, knee injuries contribute to increasing lumbar lordosis and these changes in the mechanical loads lead to pathology of the lumbar region [21]. Muscle strains and increased lumbar lordosis have been found to be associated with abnormal knee mechanics and lumbar pathologies [9]. We found that past injury locations were most prevalent in the ankle and foot. However, we found no association between injury history and non-specific LBP. We also investigated the flexibility of the low back and hamstring muscles, which is one of the intrinsic factors that may cause LBP. Shortness of the lumbar extensors, hip flexors, and hamstring muscles can cause position changes of the pelvis and increased mechanical loads in the lumbar region [8,15]. These types of changes in muscle groups of the lower extremity and in pelvis mechanics can lead to musculoskeletal injuries especially in the lumbar region. Hides et al. reported similar results for Australian elite football players and indicated that decreased flexibility negatively affected sportive performance [14]. However, no relationship between flexibility of the low back and hamstring muscles and non-specific LBP was found in our study. We determined that hamstring shortness is associated with non-specific LBP. Stewart et al. and Hides et al. reported that hamstring shortness leads to limited hip flexion during kicking and shooting activities, resulting in increased musculoskeletal loads [3,15]. This explanation could support our result; however, further investigation is needed to explain the exact mechanisms of the factors that influence non-specific LBP.
e97 Unfortunately, we were not able to examine all of the players in the Turkish Super League because most of the clubs refused to participate the present study. Therefore, to generalize the results to the Turkish professional football league, more clubs should be included in future studies. The prevalence of non-specific LBP in male professional football players in the Turkish Super League is 31.4%. The restriction of playing football was an important result of pain. Hamstring muscle shortness and the number of matches played in a starting position in a season are the predictors of non-specific LBP. Hamstring muscle length should be evaluated while planning training programs and playing high numbers of matches in a starting position in a season should be considered in terms of injury prevention. Factors which may cause LBP in male professional football players require further investigation. Additionally, to attain more certain results, studies need to be performed on a larger sample of participants.
Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.
Acknowledgements Authors would like to thank managements of the Turkish Super League Teams and department of medical statistics in Dokuz Eylul University, Turkey for their support for the statistical analysis and Kevin A Elmore for his editing of grammar, spelling and other errors of the paper.
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Disponible en ligne sur
www.sciencedirect.com
ORIGINAL ARTICLE
Non-specific low back pain in male professional football players in the Turkish super league Lombalgies non spécifiques chez les footballeurs professionnels turcs A. C ¸ali , N. Gelecek , S.S. Subasi ∗ School of Physical Therapy and Rehabilitation, Dokuz Eylül University, Inciralti 35340 Izmir, Turkey Received 2 November 2011; accepted 2 August 2012 Available online 23 January 2013
KEYWORDS Low back pain; Professional; Football; Male
MOTS CLÉS Douleur lombaire ; Professionnel ; Football ; Male
∗
Summary Objectives. — The aim of this study was to determine the prevalence and possible causes of non-specific low back pain (LBP) in male professional football players in the Turkish Super League. Methods. — A total of 121 players were questioned for demographic variables and whether they have had LBP in the last year. Player position, training characteristics, number of years as a football player, injury background and last season statistics were investigated. Flexibility of low back and hamstring muscles, and hamstring muscle length were measured. Results. — Thirty-eight football players reported non-specific LBP in last year with a prevalence of 31.4%. It was found that more matches played in a starting position and hamstring muscle shortness were significant factors for developing non-specific LBP (P < 0.05). Conclusion. — The prevalence of non-specific LBP in Turkish male professional football players is 31.4%, similar to the literature findings. Hamstring muscle shortness and high numbers of matches played as a starter are important factors for non-specific LBP. These findings should be considered for injury prevention. Causes of LBP in football players require further investigation. Studies should be performed on a larger sample of participants to attain more certain results. © 2013 Published by Elsevier Masson SAS. Résumé Objectifs. — Le but de cette étude était de déterminer la prévalence et les causes possibles de lombalgies aspécifiques chez les footballeurs professionnels masculins. Méthodes. — Les caractéristiques démographiques et la fréquence de survenue des lombalgies ont été évaluées par questionnaires chez 121 footballeurs. Les données relatives à la position du joueur, les caractéristiques de son entraînement, le nombre d’années de pratique du football, les blessures encourues dans le passé ont été recueillies. La flexibilité des muscles de la région
Corresponding author. E-mail addresses: [email protected], [email protected] (S.S. Subasi).
0765-1597/$ – see front matter © 2013 Published by Elsevier Masson SAS. http://dx.doi.org/10.1016/j.scispo.2012.08.003
e94
A. C ¸ ali et al. lombaire et des ischio-jambiers, ainsi que la longueur des muscles ischio-jambiers ont été évaluées. Résultats. — Trente-huit footballeurs ont mentionné avoir eu des lombalgies aspécifiques dans l’année qui précédait, avec une prévalence de 31,4 %. Deux facteurs de risque de survenue de lombalgie ont été retenus, l’augmentation du nombre de matchs joués pour les avants-centres et le fait d’avoir des muscles ischio-jambiers courts (p < 0,05). Conclusion. — La prévalence de lombalgies aspécifiques chez des footballeurs professionnels masculins est de 31,4 % ; cette valeur est similaire aux résultats rapportés dans la littérature. Le fait d’avoir des muscles ischio-jambiers courts et l’augmentation du nombre de matchs joués en position d’avant-centre sont des facteurs de risque de survenue de lombalgies. Ces résultats devraient être considérés pour la prévention d’accidents. Les causes des douleurs lombaires chez les footballeurs demandent des études supplémentaires, en incluant des échantillons plus importants de footballeurs. © 2013 Publié par Elsevier Masson SAS.
1. Introduction Football is one of the most popular sports worldwide [1,2]. Football requires the player to have appreciable stamina while superimposing sprinting, kicking, jumping, tackling, sudden changes of direction, and defense. It also involves a combination of repetitive, high-intensity activities [3,4]. Some researchers reported that the overall injury risk was higher in male professional football player than in industrial occupations [5,6]. It is known that lower extremity and head injuries are common among football players [7]. Furthermore, non-specific low back pain (LBP) has been documented longitudinally for the last two decades in athletes [8—10]. LBP is estimated to have yearly prevalence of 15% to 20% and a lifetime prevalence of 50% to 80% in general adult population [11]. Studies reported that rates of LBP in athletes range from 1% to 30% and are affected by the type of sport, age, gender, technique, and intensity of training [12,13]. Recently, professional football players and football players have experienced LBP more severely and frequently than non-athletic controls, particularly in the male population [14,15]. The football player carries a significant risk for acute and overuse injuries in the low back region due to excessive working of muscles in trunk, which over time, can lead to spinal mechanical overload [16]. During football game activities, neuromuscular control of the trunk is important. Trunk muscles provide adequate force to maintain normative lumbar lordosis and to stabilize and protect the vertebral column from injuries in both static and dynamic condition [15,17]. The asymmetrical changes, and ballistic tasks that involve trunk rotation and flexion in a football game are accepted as risk factors for the trunk and low back injuries due to overload on the vertebral column [15,18]. Recently, football has become more competitive requiring players to perform at a higher level, which can lead the player to repeated eccentric and concentric overload in low back region and consequently LBP problems [3,18,19]. Therefore, the back and low back regions have recently been investigated in research studies designed for classifying these injuries among football players [3,19]. Although LBP rates rise in football, there is a lack of studies specifically investigating non-specific LBP in male professional football players. For this reason, the aims of
the present study were to determine the prevalence of nonspecific LBP and to investigate the possible reasons of LBP in male professional league football players.
2. Methods 2.1. Participants The Super league is at the top of the Turkish professional football league and is the country’s primary football competition. A total of 121 male professional football players from the Turkish Super League were included in this study with a mean age of 23.8 ± 4.1 years (mean ± SD) ranged from 16 to 34 years. Study protocol was approved by the Ethics Committee of Dokuz Eylul University (case 03.07.2008/304) and performed in accordance with the ethical standards set by the 1964 Declaration of Helsinki. An informed consent form was taken from all participants at the beginning of the study after all participants’ questions were answered.
2.2. Procedures There are 18 professional football clubs in the Turkish Super League. At the beginning of the study, a letter was sent to the administrative staffs of the clubs detailing the study’s aim and test procedures. Eleven of 18 clubs refused to participate, because they will be gone out of Turkey for new season training. The rest of the clubs accepted to participate. Consequently, the study was completed with 121 professional football players. All measurements were performed at team specific locations by the same physiotherapist. Inclusion criteria for this study were active participation for the last two seasons on a professional football team and having no neurological deficit due to LBP. Exclusion criteria were the presence of lumbar intervertebral disc pathologies or past low back surgery. The anthropometric characteristics and pain existence (yes or no) were collected from their medical records and player charts. Pain characteristics and pain related functional limitations in last year were questioned. Current pain intensity, average pain intensity in last year, avoidance of performing activities of daily
Non-specific low back pain in professional soccers living (ADL), avoidance of social and family relationships and restriction of playing football according to visual analog scale (VAS) were recorded and number of off days due to pain in last year was noted. Playing positions of the participants were recorded as goalkeeper, defender, midfielder and forward. Injury history during their football careers and localizations were determined. Injury sites were divided into groups according to their frequency as: ankle/foot; knee/calf; hip/thigh; head/neck; and upper extremity. Participants were questioned for the factors that may contribute to LBP. The questions are presented below: • active years in football (amateur, professional and total); • information about last season (daily training duration [minutes], weekly training frequency [days], number of matches played last season and number of matches played last season in a starting position) [20—22]. The ‘‘Passive Straight Leg Test’’ was used for to measure hamstring length [23]. Participants were placed in supine position, lying on a pillow that supported their lumbar lordosis. A universal goniometer was used. The goniometer was placed on the trochanter major of the femur. The examiner passively flexed the hip joint while the knee was fully extended. The angle was recorded when firm resistance was detected in the hamstring muscle group or when the player wanted to stop. This procedure was repeated three times for each lower extremity and an average of all three consecutive measures was recorded. The ‘‘Sit and Reach Flexibility Test’’ was used to measure the flexibility of the low back and hamstring muscles. Assessment of tightness in this area is important due to its implication in lumbar lordosis, forward pelvic tilt, and LBP. The participant sits on the floor, legs fully extended, with the soles of their feet pressed against the sit and reach box. The participant then bends forward and reaches their fingertips as far as possible. This test was repeated three times and the average of all three consecutive measures was recorded [24].
2.3. Statistical analyses The data obtained from these measurements were analyzed with the SPSS Windows (15.0) software package. All variables were normally distributed. Therefore, results are presented as mean ± standard deviations and percentages. Descriptive statistics were used to report player characteristics, pain and functional limitations. The samples were divided into two groups of players with and without non-specific LBP. Association between non-specific LBP, demographics, and possible risk factors were analyzed using Chi2 measures. Chi2 measures were directly used for the categorical variables. Median values were calculated to categorize all the continuous variables and then Chi2 measures were applied. The level of significance was set at P = 0.05.
3. Results Mean age, height, weight, and body mass index (BMI) of 121 male professional football players are illustrated in Table 1.
e95 Table 1 players.
Anthropometric characteristics of the football Mean ± SD
Age (year) Height (cm) Weight (kg) BMI (kg/m2 )
23.8 1.8 74.4 22.8
± ± ± ±
4.1 0.1 6.3 1.2
Min—max 16—34 1.6—1.9 55—96 19.8—26.3
Min-max: minimum-maximum; SD: standard deviation.
Thirty-eight players were considered to suffer from non-specific LBP, corresponding to a prevalence of 31.4%. Average pain intensity in last year was 4.87 ± 2.14 (mean ± SD) according to VAS. Seventeen participants (44.7%) reported their pain intensity as between 1 and 4 whereas 21 participants (55.3%) reported it as between 5 and 8 according to VAS. Thirty-one players reported no current pain (81.6%). Four participants (10.5%) reported their current pain intensity as between 1 and 4 whereas three participants (7.9%) reported it as between 5 and 6. Two participants’ (5.3%) avoidance of performing ADL were over 5 (6 and 9), four participants’ (10.5%) avoidance of performing ADL were between 1 and 2. Five participants’ (13.2%) restriction of social and family relationships were between 1 and 4, 2 participants’ (5.3%) restriction of social and family relationships were 6 and 8. Furthermore, 13 participants (34.2%) reported no restriction of playing football, 22 participants (57.9%) reported their restriction between 1 and 4, three participants (7.9%) reported it between 5 and 6. Only one participant with pain intensity of 3 (2.6%) was off for 2 days, whereas five participants with the pain intensity over 5 (13.2%) were off for more numbers of days between 3 to 10 days. Association between the demographics such as age, height, body weight, and BMI with non-specific LBP was not significant (P > 0.05) (Table 2). Total active football years of the players ranged from 5 to 27 years. When the relationship of amateur, professional, and total active years of football and non-specific LBP were investigated, no significant relationship was found (P > 0.05) (Table 2). Ankle and foot injuries (56.2%) were found at higher rates compared to the injuries in the other body parts in football players, as we expected. Other injury rates were determined as knee/calf (38%), hip/thigh (35.5%), upper extremity (14.9%), and head/neck (3.3%). Injury history and non-specific LBP were not significantly correlated (P > 0.05) (Table 2). Analysis of the previous season’s statistics revealed that the weekly training frequency of all the participants was 6 days, with a daily training duration of 90 minutes. The relationship between weekly training frequency, daily training duration and LBP was therefore not analyzed due to lack of variability. There was no association between the number of matches played last season and non-specific LBP (P > 0.05), whereas the number of matches played last season in a starting position was found to be related with non-specific LBP (P < 0.05) (Table 2). It was determined that playing over 20 matches in a starting position in one season was significantly related with non-specific LBP (P < 0.05) (Table 2).
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Table 2 Association between possible risk factors and nonspecific low back pain (LBP). LBP (n) Demographics Age (years) ≤ 24 > 24 Height (cm) ≤ 180 > 180 Body weight (kg) ≤ 74 > 74 BMI (kg/m2 ) ≤ 22.7 > 22.7 Active years in football Amateur (years) ≤ 14 > 14 Profesionnal (years) ≤5 >5 Total (years) ≤ 14 > 14 Injury history Ankle & foot Yes (n) No (n) Knee and calf Yes (n) No (n) Hip and thigh Yes (n) No (n) Head and neck Yes (n) No (n) Upper extremity Yes (n) No (n) Last year statistics Numbers of matchesa ≤ 25 > 25 Starting positionb ≤ 20 > 20 Flexibility Hamstring shortness (R) ≤ 76◦ > 76◦ Hamstring shortness (L) ≤ 78◦ > 78◦ Sit and reach (cm) ≤6 >6
No LBP (n)
Table 3 Playing positions of the participants and nonspecific low back pain (LBP).
P
LBP
No LBP
Total
n
%
n
%
n
%
4 9 19 6
33.3 26.4 36.5 24
8 25 33 17
66.7 73.6 63.5 76
12 34 52 23
100 100 100 100
18 20
50 33
0.24
19 19
47 36
0.56
18 20
47 36
0.43
16 22
44 39
0.33
22 16
42 41
0.56
16 22
45 38
0.24
4. Discussion
22 16
49 34
1.00
15 (39.5%) 23 (60.5%)
53 (63.8%) 30 (36.2%)
0.30
13 (34.2%) 25 (65.8%)
33 (39.7%) 50 (60.3%)
0.69
16 (42.1%) 22 (57.9%)
27 (32.5%) 56 (67.5%)
0.31
3 (7.9%) 35 (92.1%)
1 (1.2%) 82 (98.8%)
0.91
5 (13.1%) 33 (86.9%)
13 (15.7%) 70 (84.3%)
0.79
16 22
46 37
0.24
14 24
47 36
0.04
25 13
36 47
0.03
26 12
49 34
0.04
24 14
41 42
0.17
We aimed to determine the prevalence of non-specific LBP and to investigate the reasons leading to non-specific LBP in male professional football players in the Turkish Super League. We found that the prevalence of non-specific LBP was 31.4%. Results of the present study showed that lack of flexibility in the hamstring muscles and the numbers of matches played in a starting position were significant predictors of non-specific LBP in male professional football players. Research performed in last decade reports a rate of low back problems in athletes between 1% and 30% [12,25,26]. Although the incidences vary according to the type of sport, the research was mostly conducted with fewer participants, which makes it difficult to interpret the results [12,13,17]. Sward et al. found 79% LBP in 24 elite gymnasts in their study [27], while Kujala et al. reported this percentage as 46% in adolescent athletes [28]. Lundin et al. found 37% LBP in football players while tennis players displayed 32% [29]. Yet, there is a lack of information for the prevalence of LBP in male professional football players. Non-specific LBP prevalence of male professional football players in the Turkish Super League was determined as 31.4% in our study. It can be said that the average pain intensity of those football players in a year was found as moderate and 55.3% of the players suffered pain with the intensity of 5 to 8 according to VAS. Although a few of the players (15.8%) were off for a period between 2 days to 10 days due to LBP and it seems that most of the football players could work even though they had pain, our results revealed an important point that was the restriction of playing football with the rate of 65.8%. They mostly haven’t avoided performing ADL and haven’t avoided from social and family relationships. The position and responsibilities of the players are different in a football team, even though each position consists of similar motions and acts. These differences may cause differences in injury rates and locations as well. Hawkins and Fuller reported that the risk of injury is higher in defenders than players in other positions, due to increased player
Chi2 analyses, P < 0.05; BMI: body mass index. a Numbers of matches played (number/season). b Numbers of matches played as a starter (number/season).
Goalkeeper Defender Midfielder Forward
Flexibility of low back and hamstring muscles was not related with non-specific LBP (P > 0.05), whereas hamstring muscle shortness for both dominant and non-dominant sides was significantly related with non-specific LBP (P < 0.05) (Table 2). Chi2 analyses revealed that there was no correlation between the playing positions of the participants and nonspecific LBP (P = 0.72) (Table 3).
Non-specific low back pain in professional soccers contact [21]. In our study, we found no relationship between player positions and non-specific LBP. The research is inconsistent regarding the relationship between heavy physical work, age, and LBP. Researchers found that heavy physical work may be a factor contributing to LBP [30], whereas other research indicates that working conditions do not cause LBP [18,28,31]. Kovec et al. highlighted that the risk of injury was higher in men who have jobs that require heavy and repetitive motions, and work more than 8 hours a day [30]. Van Nieuwenhuyse et al., instead, stated that physical load was not a factor for developing LBP in young individuals [31]. Parameters related with physical load such as the numbers of matches played, and the numbers of matches played in a starting position in a season were investigated. It was found that players who played more matches in a starting position in a season had more LBP. We may speculate that the players might have more micro and/or macro trauma as they play in more matches in a starting position. Additionally, we thought that playing football for a longer time might lead to heavy and repetitive work on low back region. However, in our study we found that amateur, professional, and total active years in football are not factors for developing non-specific LBP. Football naturally includes long and heavy training. Players are not only injured during games but are also injured in training sessions during season and off-season trainings. Injury history is considered as a risk factor for new injuries [5]. Injury might cause lack of flexibility at the involved anatomical location and muscle and/or joint injuries of lower extremity might trigger abnormal body mechanics, therefore low back problems. Hawkins et al. highlighted that ankle injuries deteriorate ankle biomechanics, knee injuries contribute to increasing lumbar lordosis and these changes in the mechanical loads lead to pathology of the lumbar region [21]. Muscle strains and increased lumbar lordosis have been found to be associated with abnormal knee mechanics and lumbar pathologies [9]. We found that past injury locations were most prevalent in the ankle and foot. However, we found no association between injury history and non-specific LBP. We also investigated the flexibility of the low back and hamstring muscles, which is one of the intrinsic factors that may cause LBP. Shortness of the lumbar extensors, hip flexors, and hamstring muscles can cause position changes of the pelvis and increased mechanical loads in the lumbar region [8,15]. These types of changes in muscle groups of the lower extremity and in pelvis mechanics can lead to musculoskeletal injuries especially in the lumbar region. Hides et al. reported similar results for Australian elite football players and indicated that decreased flexibility negatively affected sportive performance [14]. However, no relationship between flexibility of the low back and hamstring muscles and non-specific LBP was found in our study. We determined that hamstring shortness is associated with non-specific LBP. Stewart et al. and Hides et al. reported that hamstring shortness leads to limited hip flexion during kicking and shooting activities, resulting in increased musculoskeletal loads [3,15]. This explanation could support our result; however, further investigation is needed to explain the exact mechanisms of the factors that influence non-specific LBP.
e97 Unfortunately, we were not able to examine all of the players in the Turkish Super League because most of the clubs refused to participate the present study. Therefore, to generalize the results to the Turkish professional football league, more clubs should be included in future studies. The prevalence of non-specific LBP in male professional football players in the Turkish Super League is 31.4%. The restriction of playing football was an important result of pain. Hamstring muscle shortness and the number of matches played in a starting position in a season are the predictors of non-specific LBP. Hamstring muscle length should be evaluated while planning training programs and playing high numbers of matches in a starting position in a season should be considered in terms of injury prevention. Factors which may cause LBP in male professional football players require further investigation. Additionally, to attain more certain results, studies need to be performed on a larger sample of participants.
Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.
Acknowledgements Authors would like to thank managements of the Turkish Super League Teams and department of medical statistics in Dokuz Eylul University, Turkey for their support for the statistical analysis and Kevin A Elmore for his editing of grammar, spelling and other errors of the paper.
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