Lower limb musculoskeletal profiling in Malaysian professional footballers during pre-season pre-competition medical assessments

Mohamad Azwan Aziz; S Ahmad Hazwan; Nahar Azmi Mohamed

doi:10.4103/mohe.mohe_30_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 11 | Issue : 2 | Page : 89-96

Lower limb musculoskeletal profiling in Malaysian professional footballers during pre-season pre-competition medical assessments

Mohamad Azwan Aziz, S Ahmad Hazwan, Nahar Azmi Mohamed
Department of Sports Medicine, University Malaya Medical Centre, Kuala Lumpur ; Sports Medicine Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur, Federal Territory of Kuala Lumpur, Malaysia

Date of Submission	02-Oct-2022
Date of Decision	08-Nov-2022
Date of Acceptance	21-Nov-2022
Date of Web Publication	22-Feb-2023

Correspondence Address:
Mohamad Azwan Aziz
Department of Sports Medicine, University Malaya Medical Centre, Kuala Lumpur; Sports Medicine Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur, Federal Territory of Kuala Lumpur
Malaysia

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mohe.mohe_30_22

Abstract

Background: Lower limb musculoskeletal profiling is important in pre-competition medical assessment (PCMA) as it helps to identify musculoskeletal pathologies that need rehabilitation and risk factors for injury that need specific prevention programme. However, a normative value is needed to identify which is normal or pathological. Our objective in this study is to establish a normative value for football-specific adaptation of lower limb musculoskeletal examination among Malaysian professional footballers.
Materials and Methods: This is a prospective cross-sectional examining 83 Malaysian footballers from a single club during PCMA from 17 January 2022 to 17 February 2022. We included anthropometric assessments using body impedance analysis, objective lower limb muscle strength assessments using handheld dynamometer, range of motion and objective dynamic balance test using the Biodex system.
Results: The mean age of our study was 20.3 ± 3 years. Goalkeepers and defenders have a higher body mass index and a higher skeletal muscle mass. Strikers and midfielders have a higher quadriceps and hamstring strength. Non-dominant leg has a better overall stability and anterior posterior stability index compared to dominant leg. Defender has a better overall stability. Sixty-six footballers (80%) have at least 1 low Add: Abd ratio of less than 0.9, which requires preventive programme for groin injury.
Conclusion: This study demonstrates a position-specific adaptation in different positions in football.

Keywords: Balance, football, lower limb, muscle strength, pre-competition medical assessments

How to cite this article:
Aziz MA, Hazwan S A, Mohamed NA. Lower limb musculoskeletal profiling in Malaysian professional footballers during pre-season pre-competition medical assessments. Malays J Mov Health Exerc 2022;11:89-96

How to cite this URL:
Aziz MA, Hazwan S A, Mohamed NA. Lower limb musculoskeletal profiling in Malaysian professional footballers during pre-season pre-competition medical assessments. Malays J Mov Health Exerc [serial online] 2022 [cited 2023 Sep 25];11:89-96. Available from: http://www.mohejournal.org/text.asp?2022/11/2/89/370241

Introduction

Football is the most popular sports worldwide including Malaysia. It involves multitudinous, complex lower limb movements such as kicking, pivoting, sprinting and jumping. Thus, lower limb is commonly injured in football (77%–93%) (Arnason et al., 2004; Hagglund et al., 2005; Pfirrmann et al., 2016). Drawer and Fuller (2002) evaluated the risk of acute injuries in football and found that professional footballers have 1000 times risk of injuries as compared to any type of industrial activity (Drawer and Fuller, 2002). In his study, the prevalence of injuries was 15% during match and training and 60%–95% footballers have at least 1 injury in each season (Drawer and Fuller, 2002). Injury incidence is higher in official matches (13–40.3 injuries per 1000 match hour) as compared to training (1.9–5.9 injuries per 1000 match hour) (Arnason et al., 2004; Mallo et al., 2011; Noya Salces et al., 2014). Knee and ankle are the most frequently reported site of injuries in footballers (Arnason et al., 2004). Muscle injuries are reported as the number one cause of injuries in football (35%–50%), mainly in quadriceps, hamstring, adductor and lower leg, followed by ligament injuries (Mallo et al., 2011; Noya Salces et al., 2014).

There is a high value in performing lower limb musculoskeletal screening (strength, range of motion and balance) in pre-competition medical assessment (PCMA); (i) normative value for lower limb football-specific adaptations, (ii) early detection of risk factors of injuries and (iii) detecting current musculoskeletal pathologies (Bahr, 2016; van Dyk et al., 2018). van Dyk et al. (2016) studied isokinetic quadriceps and hamstring strength in footballs and its association with hamstring injuries (van Dyk et al., 2016). Arnason et al. (2004) examined the difference in physical characteristics among different positions among 306 male soccer players from Ireland; anthropometric, leg extension power and lower limb flexibility (Arnason et al., 2004). Bradley and Portas (2007) examined the range of motion deficit and association with muscle injuries in football (Bradley and Portas, 2007). Mosler et al. (2017) established a normative value for hip strength and range of motion among professional footballers in Qatar (Mosler et al., 2017). Wik et al., (2018) investigated the differences in physical characteristics of lower limb in different football positions (Wik et al. 2018). Gonell et al. (2015) demonstrated that lower balance was more likely to sustain a lower extremity injury (P = 0.001) (Gonell et al., 2015). Establishing normative value for football-specific adaptation of lower limb is crucial as it will benefit the clinician to tackle risk factors of lower limb injuries. To the best author's knowledge, there was no such study that has been performed among Malaysian populations. Thus, there is a requisite for normative value among professional Malaysian footballers. This study aims to establish a normative value for football-specific adaptation of the lower limb musculoskeletal examination among Malaysian professional footballers and examine the differences in lower limb characteristics in different football positions.

Materials and Methods

Study design

This was a prospective cross-sectional study. Professional footballers from single renowned football club in the Malaysian league, who came for pre-PCMA in the Sports Medicine Unit, University of Malaya, from 17^th January 2022 to 17^th February 2022, were included in this study. Assessments of PCMA were completed by skilled sports and exercise physician trainee, who underwent intensive course before pre-PCMA and had more than 1-year experience in sports and exercise medicine. There were 94 footballers participated in PCMA. However, 10 international and 1 injured footballers were excluded from this study.

Pre-competition medical assessments

Footballers asked to rest for 1 day before PCMA. There were few components assessed and included in this study: demographic data, dominant leg, joint range of motion, muscle strength assessments, joint laxity and dynamic balance assessments. Demographic data collected were age, gender and position played. Name, identification number and football club name were collected but were excluded from the analysis. Other assessments which were required by Football Association Malaysia (FAM), such as medical history, upper limb and spine examinations were performed but were excluded in this study. Data were recorded in the standardised report form and FAM PCMA forms.

Footballers were asked to fast for 6 h before the test. Anthropometric measurements were taken using Inbody 370 Body Composition Analysis. Joints range of motion was measured using goniometer, by single identical examiner (examiner 1) throughout the PCMA. The techniques of range of motion are outlined in [Supplementary Table 1]. Lower limb muscle strength assessments were carried out by a single identical examiner (examiner 2) as well as using JTECH Commander Powertrack Muscle Dynamometer manual muscle testing. The techniques of lower limb muscle strength assessments are outlined in [Supplementary Table 2]. We choose objective muscle testing using a handheld dynamometer as it has a (i) high correlation between hip, knee and ankle strength compared to isokinetic, (ii) cheaper and (iii) is applicable as bedside examination in clinic and office (Chamorro et al., 2017). An objective dynamic balance test using Biodex Balance System was assessed by a single identical examiner (examiner 3). The Biodex Balance System SD (Biodex Medical Systems Inc, Shirley, New York, USA) aims to test the dynamic postural stability on an unstable multiaxial platform (Riemann et al., 2003). It measures the degree of tilt at the sagittal plane (anterior–posterior stability index [API]), frontal plane (medial-lateral stability index [MLI]) and degrees in all motions (overall stability index [OSI]). The nearer the indices to zero, the higher the balance performance. Thus, the aim of the test is to remain static while maintaining the platform as level and stationary as possible (Riemann et al., 2003). The feet were placed in their most comfortable position to maintain the dot at the centre and malleolar aligned. After positioning, footballers were instructed to maintain their foot position until the end of the test. The position of the foot (heel position and foot angle) were documented according to the grip. Footballers asked to 'maintain the platform as level and stable and motionless as possible' while looking straight ahead and maintaining their hands on their iliac crests throughout the entire trial. A broke posture defined as the hands lifted from the iliac crests, touching down with the contralateral limb, or moving the contralateral limb into more than 30° of hip flexion or adduction results in invalid test. Thus, the test trial was repeated one more time for the broke posture. One leg was tested individually. The OSI, API and MLI were recorded for each trial. The average of three results was recorded (Riemann et al., 2003). We were using level 4 difficulties in assessing the footballers. This study was approved by Medical Research Ethics Committee, University Malaya Medical Centre.

Data analysis

Descriptive analysis was done for anthropometric, lower limb range of motions, lower limb muscle strength and lower limb dynamic balance and expressed as mean (standard deviation). Normality of the data was assessed using the visual inspection and the Shapiro–Wilk test. As the data were not normally distributed, the comparison of anthropometrics, lower limb range of motions, lower limb muscle strength and lower limb dynamic balance between the different groups using the Kruskal–Wallis H test and expressed as median (interquartile range). Data were analyzed using IBM Corp. (2020). IBM SPSS Statistics for Windows (Version 27.0).

Results

Out of 94 footballers, only 83 were included in our study. The mean age of our footballers was 20.3 ± 3 years. 32.5% (n = 27) were defenders, 30.1% (n = 25) were midfielders, 24.1% (n = 20) were striker and 13.3% (n = 11) were goalkeepers. Seventy-seven per cent (n = 64) were right leg dominant and 23% (n = 19) were left leg dominant. Thirty-six per cent of them had previous history of lower limb injuries. [Table 1] shows the demographic and anthropometric data of our footballers. In our study, goalkeepers and defenders have a higher weight, body mass index (BMI) and higher skeletal muscle mass, as shown in [Table 2].

Table 1: Descriptive analysis of the anthropometric assessments in 83 Malaysian footballers

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Table 2: Differences in anthropometrics assessments in different football positions

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For range of motion, the range of motion of hip, knee and ankle joints was similar in dominant and non-dominant leg. We did not identify any significant range of motion-specific adaptation in different football positions. Details of the findings are reported in [Table 3] and [Table 4].

Table 3: Descriptive analysis of the range of motion assessments in hip, knee and ankle in 83 Malaysian footballers

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Table 4: Differences in range of motion assessments in hip, knee and ankle joints in different football position

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For muscle strength assessments, dominant legs demonstrated a higher hip extension, adduction and abduction compared to non-dominant leg. Sixty-six footballers (80%) have at least 1 low Add: Abd ratio of <0.9. However, the knee strength of flexion and extension and ankle strength; dorsiflexion, plantar flexion, inversion and eversion were similar in the dominant and non-dominant leg. Details of the findings are available in [Table 5]. When compared with different football positions, strikers and midfielders have a higher hip, knee and ankle strength, as shown in [Table 6].

Table 5: Descriptive analysis of the muscle strength assessments in hip, knee and ankle in 83 Malaysian footballers

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Table 6: Differences in muscle strength assessments in hip, knee and ankle joints in different football position

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For the dynamic balance test, non-dominant leg a slightly better overall stability and anterior posterior stability as compared to dominant leg, as shown in [Table 7]. In comparison with different football positions, defenders have the best overall stability, as shown in [Table 8].

Table 7: Descriptive analysis of the lower limb dynamic assessments in hip, knee and ankle in 83 Malaysian footballers

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Table 8: Differences in lower limb dynamic assessments in different football position

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Discussion

This would be the first study to perform lower limb musculoskeletal profiling, which includes range of motion, muscle strength, and proprioception among professional Malaysian footballers.

Anthropometric assessments

Our footballers have similar findings of mean for BMI (22.6 ±1.8 kg/m²) to Azwan Aziz et al. (2021) (22.7 ± 2.1 kg/m²) and Aziz and Abu Hanifah (2021) (22.6 ± 7), who had examined Sabah footballers and elite female footballers (22.3 ± 2.3 kg/m²) (Aziz and Abu Hanifah, 2021; Hassan et al., 2020; Risberg et al., 2018). Recreational footballers have a higher BMI (26.40 ± 2.08 kg/m²) as compared to our study with their mean age of 31.80 ± 5.46 years (Meo et al., 2021). Defensive players have a significantly higher BMI than offensive players. Goalkeepers have the highest BMI, whereas midfielders have the lowest BMI. This study is consistent with many international studies (Arnason et al., 2004; Boone et al., 2012; Sporis et al., 2009). This study reflects the position-specific demands in football. Lower BMI seen in our offensive players was due to a lower skeletal muscle mass and percentage body fat. This is because midfielders and strikers are high metabolic demand positions, as it needs to cover a longer distance during tournament compared to goalkeepers and defenders (Boone et al., 2012; Di Salvo et al., 2007). Strikers has the highest metabolic demand among all football position, as they need to perform aat high to very high intensities (Bloomfield et al., 2007). Krustrup et al. found that midfielders tend to have the lowest body fat percentage as compared to the other playing positions (Krustrup et al., 2005). According to Reilly et al. (1990), there is a strong relation between the body composition and fitness of male soccer players (Reilly et al., 1990).

Range of motion

There was no significant difference in range of motion of the hip, knee and ankle on different football positions in this study. Arnason et al. (2004) demonstrated a significant difference in hip flexion and extension between offensive players and goalkeepers (Arnason et al., 2004). Malaysian footballers have a slightly higher hip external rotation and abduction than international Qatar Stars league footballers (Mosler et al., 2017). Spanish footballers have a higher range of motion of hip flexion, internal and external rotation, abduction and lower hip extension as compared to our study (Lopez-Valenciano et al., 2019). López-Valenciano et al. (2019) also reported a higher ankle dorsiflexion in knee extension range of motion compared to our study (Lopez-Valenciano et al. 2019). However, this study was conducted in the standing position, while our study was conducted in the lying position. Thus, a standardised measurement technique should be done to report reliable outcomes.

Strength

Muscle strength is crucial for performance and injury prevention. In our study, strikers and midfielders have higher hip muscle strength than defenders and goalkeepers. Our non-dominant hip abductor strength (3.06 Nm/kg) is slightly lower than the dominant side (3.4 Nm/kg), with a difference of 10%. Our hip abductor strength was higher as compared to Thorborg et al. (2011) study (2.5 Nm/kg with no difference between dominant and non-dominant lower limb) and Mosler et al. (2016) study (2.6±0.4 Nm/kg with no difference between dominant and non-dominant lower limb (Mosler et al., 2017; Thorborg et al., 2011) Our hip adductor strength (2.87 Nm/kg) is significantly lower as compared to dominant side (3.1 Nm/kg) with a difference of 7.4%. These findings were slightly higher compared to Thorborg et al. (2011) (dominant = 2.8 Nm/kg, non-dominant = 2.5 Nm/kg with a 13% difference between dominant and non-dominant lower limb) and Mosler et al. (2017) study (3.0 ± 0.6 Nm/kg with no difference between dominant and non-dominant lower limb) (Mosler et al., 2017; Thorborg et al., 2011). Our mean hip ADD:ABD ratio (dominant: 0.92 ± 0.2, non-dominant: 0.97 ± 0.2) was within borderline range (normal: 0.9–1.4). These findings were slightly lower compared to professional Qatar Star League player (1.2 ± 0.2). Any player who had ADD: ABD ratio less than 0.9 was recommended for hip adductor strengthening program to reduce risk of groin pan syndrome. Hip strength, especially hip adduction and abduction, is crucial in the prevention and treatment of groin injury in football (Krommes et al., 2017). Thus, regular examination of hip strength is recommended as the part of the management of footballers.

In our study, strikers and midfielders have higher lower limb muscle strength as compared to goalkeepers and defenders. This is contrary to many other studies. Wik et al. (2018) demonstrated higher relative isokinetic knee flexion and extension in defenders (Wik et al., 2018). Brazilian professional footballers reported a higher quadriceps and hamstring strength in goalkeepers (Ruas et al., 2015). However, the muscle torque was not normalised with body mass. Polish professional footballers demonstrated a lower isokinetic strength in goalkeepers and midfielders (Sliwowski et al., 2017). There is no significant difference between the dominant extensor strength and non-dominant extensor (3.2 ± 0.8 Nm/kg). According to Fousekis et al. (2010), footballers tend to develop an asymmetrical motor pattern, due to distinct use of dominant leg for kicking, cutting and passing balls (Fousekis et al., 2010). Contrary to many studies, our study did not confirm that findings (Fousekis et al., 2010; McLean and Tumilty, 1993) Hamstring to Quadriceps ratio (H:Q) in our study was within normal range (1 ± 0.2). Average H:Q is between 0.5–0.8, with a ratio above 1 provide a greater stability to the knee joint (Rosene et al., 2001).

Dynamic stability

To the authors knowledge, this is the first study to compare single leg athlete proprioception among different positions in football. Footballers require a high static and dynamic balance as it involves jumping, landing, pivoting and cutting. Thus, proprioception is a crucial part of assessment and performance training in football. Interestingly in our study, non-dominant legs (1.36 ± 0.5) have a slightly better overall stability than dominant legs (1.3 ± 0.4), slightly better anterior-posterior stability on non-dominant leg (0.9 ± 0.3) than dominant (0.8 ± 0.2), and medial lateral stability on non-dominant legs (0.9 ± 0.3) than dominant (0.9 ± 0.2). Riemann and Davies (2013) reported similar findings that non-dominant legs have a better dynamic balance (Riemann and Davies, 2013). Proprioception is also influenced by sex and anthropometric (Riemann and Davies, 2013). Another interesting finding, we found that defenders demonstrated a better overall stability as compared to strikers. Bloomfield reported that defenders spend more time on purposeful movement (standing, walking, jogging, running sprinting and skipping) as compared to strikers (Bloomfield et al., 2007). Single-leg balance most accurately replicates the sporting movements and may better encompass an athlete's potential to maintain balance (Emery, 2003).

This study will serve as a baseline for football-specific lower limb adaptation among Malaysian footballers. We used the methods of assessments that are applicable as a bedside examination in clinic or in office. However, few limitations should be outlined in this study. Although in each examination, there was a single identical examiner assessed the specific lower limb profile throughout PCMA, a reproducible of findings are crucial to assess the reliability of the data. Isokinetic testing is a more objective assessment of muscle strength using a specific angle velocity and exhibiting dynamic muscle movement as compared to the isometric hand-held dynamometer. Dynamic balance assessments methods and reporting using Biodex are not standardised across many studies. The inconsistency in reporting the data leads to difficulties to interpret the data judiciously. There should be a standard guide in reporting Biodex balance assessments so that results can be interpreted and compared in future research.

Conclusion

In this study, we were able to demonstrate a position-specific adaptation in different positions of football. Goalkeepers and defenders have a higher BMI and higher skeletal muscle mass. Striker and midfielder have a higher quadriceps and hamstring strength, and defender has a better overall stability. There was no position-specific adaptation for joint range of motion in our study.

Acknowledgment

We thank all sports physician, sports medicine trainees and staffs in Sports Medicine Department, University Malaya Medical Centre that was highly involved in the PCMA.

Data availability statement

Data are available within its supplementary materials upon request.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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