Isokinetic Strength, Bilateral and Unilateral Strength Differences: Variation by Age and Laterality in Elite Youth Football Players

Malý, Tomáš; Ford, Kevin R.; Sugimoto, Dai; Izovska, Jana; Bujnovsky, David; Hank, Mikuláš; Cabell, Lee; Zahálka, František

doi:10.4067/s0717-95022021000100260

Cited by 8 publications

(16 citation statements)

References 25 publications

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“…The main finding of our study was the significant (p < 0.05) effect of the AC on the prevalence of BA in KEs and KFs among the analyzed categories (U13, U15, and U17). However, the study by Maly et al [17] did not confirm this finding in their analysis of the U16-U21 categories. The study presented lower BA average values (Q:Q = 7.97-9.29%, H:H = 7.94-11.47%) than those in our study (Q:Q = 6.29-11.10%, H:H = 7.79-12.12%), suggesting that longer playing and training durations improve the neuromuscular environment; thus, athletes become more resilient and BA appears to be stabilized [25].…”

Section: Discussionmentioning

confidence: 79%

“…One possible reason is the reduced ability to cope with pre-existing asymmetries from incomplete maturation of their kinetic and neuromuscular patterns. Contrastingly, Maly et al [17] did not confirm a significant effect of age on BA level, although they presented higher average values of BA in KEs and knee KFs in the older categories (U19 and U21) than in the younger categories (U16 and U17).…”

Section: Introductionmentioning

confidence: 78%

“…Although strength BA as a negative factor for health and performance is well researched in professional soccer [3,4,7,12,15], we observed a paucity of literature on BA in various stages of childhood and adolescence in elite youth players. Some authors have attempted to clarify the effect of maturation [10,16] and chronological or professional training age [8,17,18] on the BA level; however, the conclusions vary. Atkins et al [16] examined BA during a deep squat test and concluded that the highest imbalance was observed at the age of 13−15 years, which is closely related to the well-regarded limit of the largest maturity-related changes in physical performance [19].…”

Section: Introductionmentioning

confidence: 99%

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Bilateral Strength Asymmetry in Elite Youth Soccer Players: Differences between Age Categories

et al. 2021

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The strength asymmetry of athletes as a negative health and performance factor is increasingly being researched in sports with a high load on the dominant limb when some specific unilateral movements, such as passing, jumping, and tackling, are required. This study aimed to determine the level of isokinetic strength bilateral asymmetry (BA) among knee extensors (KEs) and knee flexors (KFs) of elite youth soccer players. The sample (n = 87) consisted of three age categories of under 13 (U13), under 15 (U15), and under 17 (U17) years old. Isokinetic dynamometry was used to obtain the maximum peak torque of the KEs and KFs in the dominant and non-dominant lower limbs during concentric muscle contraction. The analysis revealed significantly lower values (p < 0.05) of BA in KEs in U17 than in younger categories, U13 and U15, and higher values (p < 0.05) of BA in KFs in the U15 category than in the U17category. The majority of the players in the U15 category (68%) reached KFs BA higher than 10% in comparison with U13 players (50%) and U17 players (28% of players) (p < 0.05). Our results showed a significant effect of age category on BA levels in young soccer players. High incidences of increased BA in the lower limbs occurred in the younger categories (U13, U15) and subsequently decreased in the later adolescent stages.

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Section: Discussionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

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Bilateral Strength Asymmetry in Elite Youth Soccer Players: Differences between Age Categories

et al. 2021

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“…Limb preference is the preferred leg (PL) while kicking a ball, according to one definition. 29 During the 2021–2022 season, all competitors played in the First Portuguese League.…”

Section: Methodsmentioning

confidence: 99%

Lower limbs strength variations between injured and non-injured professional soccer players

Martins,

França,

Sarmento

et al. 2024

Science Progress

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Due to its physical demands, professional soccer is becoming a real challenge regarding players’ exposure to high injury risk. Given its tight correlation with high-intensity actions, muscular strength is a crucial physical characteristic for soccer players. Therefore, the aims of this study are (a) to compare the vertical jumping performance during the season according to the injury profile, and (b) to investigate differences in isokinetic strength performance at the beginning and the end of the season. Twenty-one male professional soccer players (age: 26.0 ± 4.1 years, height: 181.0 ± 6.9 cm, body mass: 73.7 ± 6.9 kg) were assessed in isokinetic strength (Biodex System 4 Pro Dynamometer), and Optojump Next (Microgate, Bolzano, Italy). Isokinetic strength analyses considered the peak torque scores of knee flexors and knee extensors, according to the player's preferred and non-preferred limb. The countermovement and squat jump maximum height were assessed as lower body explosive strength indicators. No significant differences were found when comparing injured and non-injured players in vertical jump and isokinetic strength assessments. However, significant results were found when comparing both groups’ initial and final evaluation in isokinetic strength assessment, with both groups significantly improving their performance. Our findings indicate that the overall lower body strength performance was not a discriminant factor between injured and non-injury players. Thus, muscular strength assessment performance increased throughout the season independently of the injury profile. Future research needs to integrate other variables related to sports injuries since they seem to result from multifactorial causes.

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“…They can manifest in aspects ranging from gait mechanics to the change of direction differences (Nicholson et al, 2022). However, the largest BLA in soccer has been reported in lower limb strength (Nicholson et al, 2022), with this being affected by long-standing participation in soccer (Fousekis et al, 2010b;Maloney, 2019;Maly et al, 2021). Côté et al (2007) reported that elite players achieved more hours in specific football training during childhood and adolescence compared to those who did not achieve professional status.…”

Section: Introductionmentioning

confidence: 99%

Relationships of lower extremity and trunk asymmetries in elite soccer players

Maly,

Hank,

Verbruggen

et al. 2024

Front. Physiol.

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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 (ηp2) 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.

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Isokinetic Strength, Bilateral and Unilateral Strength Differences: Variation by Age and Laterality in Elite Youth Football Players

Cited by 8 publications

References 25 publications

Bilateral Strength Asymmetry in Elite Youth Soccer Players: Differences between Age Categories

Bilateral Strength Asymmetry in Elite Youth Soccer Players: Differences between Age Categories

Lower limbs strength variations between injured and non-injured professional soccer players

Relationships of lower extremity and trunk asymmetries in elite soccer players

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