Normative data for hip strength, flexibility and stiffness in male soccer athletes and effect of age and limb dominance

Assessment of Strength and Power Capacities in Elite Male Soccer: A Systematic Review of Test Protocols Used in Practice and Research

BACKGROUND

Strength and power represent two crucial physical qualities for the attainment of a high level of performance considering the frequency and the importance of explosive actions occurring during elite soccer match-play. Evaluation of strength and power is a multifaceted concept involving a vast array of tests and outcome variables. Nevertheless, a comprehensive and systematic search of strength and power assessment procedures in elite soccer has yet to be undertaken.

OBJECTIVES

The aims of this systematic review were to: (1) identify the tests and outcome variables used to assess strength and power of elite male soccer players; (2) provide normative values for the most common tests of strength and power across different playing levels; and (3) report the reliability values of these strength and power tests.

METHODS

A systematic review of the academic databases MEDLINE, CINAHL, SPORTDiscus, Web of Science and OVID for studies published until August 2023 was conducted, following the Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were eligible for inclusion if they: (1) were original research studies, published in a peer-reviewed journal, and written in English language; (2) had the primary aim to assess strength and/or power; (3) players were male and older than 17 years of age (i.e., mean age of the group); and (4) their playing level was defined as "professional", "international" or "elite".

RESULTS

Regarding strength testing, 115 studies and 29 different tests were identified. The three most frequent strength tests were the knee extensor isokinetic strength test (58 studies), the knee flexor isokinetic strength test (55 studies) and the Nordic hamstring strength test (13 studies). In terms of power testing, 127 studies with 31 different tests were included. The three most frequent power tests were the countermovement jump with hands fixed on hips (99 studies), the squat jump (48 studies) and the vertical jump with arm swing (29 studies).

CONCLUSIONS

The wide range of different tests and outcome variables identified in this systematic review highlights the large diversity in the employed testing procedures. The establishment of a hybrid testing approach, combining standardised and widely accepted tests for establishing normative standards and enabling comparisons across different contexts, with flexible context-specific testing batteries, has the potential to maximise the impact of testing information for practitioners. In addition, the limited reporting of reliability data across studies highlights the need for practitioners to establish their own reliability measure within their specific contexts, informing the selection of certain tests and outcome variables.

Relationships of lower extremity and trunk asymmetries in elite soccer players

In light of previous research highlighting the prevalence of asymmetries in soccer players and possible links to injury risks, there is a crucial gap in the biomechanical understanding of complex relationships between lower extremity and trunk asymmetries in elite soccer players. The purpose of this study was to investigate the level, relationships, and differences among twelve different parameters of strength, morphological, and neuromuscular asymmetries in elite soccer players. Methods: Elite male soccer players (n = 25, age 21.7 ± 3.9 years) were tested in the following tests: bilateral fluid distribution, hip flexor range of motion, postural stability, isokinetic strength of knee extensors and flexors, isometric lateral trunk rotation strength, eccentric strength of knee flexors, isometric bilateral strength of hip adductors, and vertical ground reaction force in counter-movement jump-free arms, counter-movement jump, squat jump, and drop jump tests. One-way ANOVA, Pearson's coefficient (r), and partial eta squared (η p 2) were used for data analysis. Results: Significant differences in asymmetries were found in elite soccer players (F11,299 = 11.01, p < .01). The magnitude of asymmetry over 10% was in postural stability and drop jump parameters. The lowest magnitudes of asymmetries were in the fluid distribution of the lower limbs and the vertical ground reaction force during the take-off phase in squat jumps. The highest asymmetries between the dominant and non-dominant sides were found in postural stability and drop jump. A total of eleven significant correlations (p < 0.05, r = 0.41-0.63, R2 = 0.17-0.40) were detected between the analyzed asymmetries in elite soccer players. The lateral trunk rotation asymmetries were significantly correlated to vertical ground reaction force asymmetries and knee extensors. Conclusion: Long-term exposure in elite soccer leads to unilateral biomechanical loading that induces abnormal strength and morphological adaptations in favor of the dominant side while linking lower limb and trunk strength asymmetries. By unraveling these complex relationships, we strive to contribute novel methods that could inform targeted training regimens and injury prevention strategies in the elite soccer community. The data should encourage future researchers and coaches to monitor and develop trunk strength linked to lower body kinematics.

The relationship between lower extremity muscle tightness and pain and disability in individuals with non-specific chronic low back pain

BACKGROUND

Low back pain is a common health issue, and such pains are often associated with muscle tightness. Understanding the link between lower back pain and tight lower extremity muscles is essential for effective pain management and enhanced quality of life.

OBJECTIVE

The objective of this study was to investigate the relationship between lower extremity muscle tightness and pain and disability in individuals with non-specific low back pain (NSLBP).

METHODS

A total of 52 individuals with NSLBP were enrolled in this cross-sectional study. Lower extremity muscle tightness was assessed using various clinical tests, including the Active Knee Extension Test, Active Straight Leg Raise, Ober Test, and Modified Thomas Test. Pain intensity and disability were evaluated using the Visual Analog Scale and the Oswestry Disability Index, respectively. Statistical analyses were conducted to assess the correlation between muscle tightness, pain, and disability.

RESULTS

The study found weak to moderate negative correlations between lower extremity muscle tightness and both pain intensity and disability in individuals with NSLBP (r: -0.287 to -0.526, p < 0.05). Dominant and non-dominant extremities exhibited differences in muscle flexibility, with the dominant extremity showing greater flexibility (p < 0.05).

CONCLUSIONS

In individuals with NSLBP, lower extremity muscle tightness is closely related to pain severity and disability. These findings suggest that lower extremity muscle tightness plays a significant role in the severity of low back pain and disabilities. Additionally, the observed flexibility difference between dominant and non-dominant extremities warrants further investigation for more personalized treatment approaches.

Isokinetic Assessment of Knee Flexor and Extensor Strength and Lower Extremity Flexibility Assessment of an NCAA Division III Men's Soccer Team

Background

Strength imbalances and flexibility deficits of the hamstrings and hip flexors have been identified as potential risk factors for hamstring injuries, but research on athletes at the Division III level are limited, potentially due to a lack of resources and technology.

Purpose

The purpose of this study was to conduct isokinetic and flexibility assessments to screen male soccer athletes at risk of sustaining a hamstring injury.

Study Design

Observational cohort.

Methods

Standardized isokinetic testing of concentric muscle performance, measured by peak torque of the quadriceps and hamstrings and hamstring-to-quadriceps ratios, was conducted using a Biodex isokinetic dynamometer at speeds of 60 and 180°/sec. Additionally, the Active Knee Extension (AKE) test and the Thomas test were performed bilaterally to objectively measure flexibility. Paired sample t-tests were used to compare left and right lower extremities for all outcomes, with the level of significance set at p<0.05. Participants were ranked for risk and given a set of exercises sourced from the FIFA 11 Injury Prevention Program.

Results

At 60°/sec, the mean PT/BW bilateral deficit was 14.1% for extension and 12.9% for flexion. At 180°/sec, the mean deficit was 9.9% for extension and 11.4% for flexion. The team's average for left and right H:Q ratios for each speed were 54.4 and 51.4 at 60°/sec and 61.6 and 63.1 at 180°/sec, respectively. The team's average AKE range of motion was 158° for the left leg and 160° for the right leg. The mean Thomas test measurements were 3.6° away from the neutral position on the right and 1.6° on the left, with nine positive tests. There were no statistically significant differences between left and right knee extension or flexion PT/BW or H:Q ratios at either speed. There was no significant difference between left and right AKE measurements (p=0.182).

Conclusion

The results of this screening suggest that isokinetic testing and flexibility testing may be useful to identify non-optimal strength ratios and flexibility deficits in male collegiate soccer players. The benefits of this research have direct implications, as participants received both their screening data and a set of exercises aimed to help decrease their injury risk, in addition to the offering data that is useful for determining what normative values for flexibility and strength profiles might look like for Division III male soccer players.

Level of Evidence

Level 3.

Dynamometric Strength Profile of Hip Muscles in Youth Soccer Players

BACKGROUND

Soccer is the most widely practiced sport in the world, demanding high-speed activities such as jumps, sprints and changes of direction. Therefore, having optimal levels of muscle strength improves performance and reduces the injury rate.

OBJECTIVES

The objectives of our study were (i) to determine the dynamometric profile of hip muscle strength in young soccer players by position, evaluated at different isokinetic speeds, (ii) to describe the conventional and functional unilateral muscle strength ratios, (iii) to analyze the bilateral balance.

METHODS

Thirty-seven male soccer players (age 17.02 ± 0.92 years) participated in the study. Strength assessment was performed with a functional electromechanical dynamometer, and concentric and eccentric strength of abductors, adductors, extensors and hip flexors were measured bilaterally at 0.5 m/s and 1 m/s.

RESULTS

For eccentric right hip abduction at 0.5 m/s, defenders are significantly stronger than midfielders (p = 0.013) and stronger than forwards (p = 0.140). For eccentric right hip adduction at 0.5 m/s, defenders are significantly stronger than midfielders (p = 0.005) and stronger than forwards (p = 0.253), as for eccentric right hip adduction at 1 m/s, defenders are significantly stronger than midfielders (p = 0.014) and stronger than forwards (p = 0.084). There is a significant effect for the conventional strength ratio of left abduction/adduction at 1 m/s. The conventional strength ratio of forwards is significantly higher than that of defenders (p = 0.045) and higher than that of midfielders (p = 0.152).

CONCLUSIONS

Concentric and eccentric hip strength values differ according to playing position.

Hip external rotation isometric torque for soccer, basketball, and volleyball athletes: normative data and asymmetry index

BACKGROUND

Deficits in strength of the hip external rotators (ER) affect trunk, hip, and knee movement patterns, potentially contributing to injury in athletes.

OBJECTIVES

To provide normative data on isometric torque for hip ER in athletes of three distinct sports and to determine if isometric torque for the hip ER and torque asymmetry between legs differ among sports and between sexes.

METHODS

Basketball, soccer, and volleyball athletes (n=451) were evaluated. Hip ER torque was quantified bilaterally with athletes in prone and 90° of knee flexion using a hand-held dynamometer.

RESULTS

Data are expressed as mean and 95% confidence interval. Hip ER torque values in Nm/kg for the dominant and non-dominant limbs were, respectively, 0.46 (0.44, 0.48) and 0.42 (0.40, 0.44) for male soccer athletes; 0.35 (0.32, 0.37) and 0.27 (0.25, 0.29) for male basketball athletes; and 0.37 (0.34, 0.39) and 0.35 (0.32, 0.37) for male volleyball athletes. Hip ER torque in Nm/kg for the female volleyball athletes was 0.29 (0.26, 0.33) for the dominant and 0.29 (0.25, 0.32) for the non-dominant limb. The Limb Symmetry Index for male soccer, basketball, and volleyball players was, respectively, 94% (91, 97), 81% (75, 87), and 95% (91, 99). For female volleyball players the Limb Asymmetry Index was 102% (95, 108). Male volleyball athletes showed higher torque values than female volleyball athletes.

CONCLUSIONS

This study reported normative values for hip ER isometric torque of youth athletes. Clinicians can use the reported data as reference to identify torque deficits in athletes of the three reported sports.

Morphological and Fitness Attributes of Young Male Portuguese Basketball Players: Normative Values According to Chronological Age and Years From Peak Height Velocity

The aims of the present study were: (i) to describe the structural and functional attributes of young male Portuguese basketball players aged 12-16 years and (ii) to generate normative data according to chronological age and years from peak height velocity. A total of 281 male Portuguese young basketball players between the ages of 12 and 16 years were assessed in this study. Chronological age, maturity parameters (maturity offset and predicted age at peak height velocity), morphological (body mass, height, and skinfolds and length), and fitness (sprint, change of direction ability, jump, and upper body strength) attributes were measured. Descriptive statistics were determined for the age and maturity status, and the 10th, 25th, 50th, 75th, and 90th percentiles were chosen as reference values. Descriptive and normative values of the players' morphological and fitness attributes, stratified by age and maturity status, are provided. The normative values of age at peak height velocity (category YAPHV = 0) showed that regional basketball players presented average values (50th percentile) of 169.8 cm for height, 173.3 cm for arm span, 55.6 kg for body mass, 3.34 s for the 20-m speed test, 10.31 s for the T-test, 4.75 m for the 2-kg medicine ball throw, 66.9 kg for the combined right and left handgrip strength, and 30.1 and 35.9 cm for jump height in the countermovement jump (CMJ) and CMJ with arm swing, respectively. In conclusion, these results may be helpful to quantify and control an athlete's performance over time and to adjust strength and conditioning programs to biological demands.