Strength development and non-contact lower limb injury in academy footballers across age groups

Hip adduction and abduction strength values in elite-level male and female youth soccer players: A comparison between sexes, and across age-groups

OBJECTIVES

To report isometric hip adduction squeeze and abduction press strength values of elite-level youth male and female soccer players and examine if differences exist between sexes, and age-groups.

DESIGN

Cross-sectional cohort study.

SETTING

Elite youth soccer academy.

PARTICIPANTS

102 soccer players (n = 64; male, n = 38 female) competing in the national youth soccer leagues from under (U) 14-19 years of age level (U-14, U-15, U-17, U-19).

MAIN OUTCOME MEASURES

Isometric hip adduction and abduction strength values were measured with a ForceFrame in various testing positions.

RESULTS

Isometric hip adduction and abduction strength values are presented. Male U-17 and U-19 players demonstrated significantly greater (p < 0.05) absolute(N) and relative (N/kg) hip adduction and abduction strength than their female counterparts, with large (η2 = 0.068-0.227) and medium-to-large (η2 = 0.049-0.234) effect size, respectively. Significant differences in absolute strength, but not relative strength, were observed for hip adduction and abduction between male age-groups (U-14, U-15, U-17, U-19), with hip abduction strength differences only existing between U-14 and U-17 groups. No significant differences in hip strength were observed between U-17 and U-19 groups for female players.

CONCLUSION

Male youth soccer players have higher absolute and relative hip adduction and abduction strength than females at the U-17 and U-19 level.

Elit genç futbol akademisi sporcularında yaralanma insidansı: 3 yıllık geriye dönük takip

Aim: The aim of this study was to investigate the incidence and characteristics of injuries suffered by elite soccer academy athletes. Materials and Methods: A retrospective analysis was made of the health records between 2016 and 2019 of athletes in the elite male soccer academy of an elite football club. The cause, type, location, recurrence, and severity of the injuries, where the injuries occured and time lost due to the injuries were recorded. The injury incidence and prevalence were calculated. Results: Overall, total injuries and seasonal incidence rate were 1.49 (1.33-1.68) and 8.06 (7.16-0.04) per 1000 hours, respectively. The injury burden ranged between 11.83 (10.53-13.29) days and 51.43 (49.11-53.85) days. The injury characteristics were not statistically different according to age groups (p˃0.05). Conclusion: Youth soccer players in the U19 and U21 age groups had more injuries than other junior age groups in a typical soccer season. It was concluded that there were more match injuries, the thigh was the most injured area, muscle injuries were more common, and the hamstring was the most frequently injured muscle.

Rapid Spike in Hip Adduction Strength in Early Adolescent Footballers: A Study of 125 Elite Male Players From Youth to Senior

PURPOSE

To investigate the differences in hip adductor and abductor muscle strength in elite male footballers from youth to senior level.

METHODS

We tested 125 players from the under-13-years (U'13) to senior squads of a Danish male professional football club in this cross-sectional design study. Hip adductor and abductor force (in newtons), torque (in newton meters), normalized torque (in newton meters per body mass), and adduction-to-abduction ratio were measured using handheld dynamometry.

RESULTS

Between U'13 and senior level, adductor force increased by 104%, torque by 127%, and normalized torque by 21%. Abductor force increased by 78%, torque by 126%, and normalized torque by 17%. For incremental differences between age groups, significant increases were observed between the ages of U'13 to U'14 (18%-39%) and U'14 to U'15 (19%-33%) for all strength measures (P ≤ .021). No incremental difference was observed for adductor-to-abductor ratio.

CONCLUSIONS

The large increases in hip adductor and abductor strength occurring between the ages of U'13 and U'15 offer insight into the strength capabilities and stress demands in these players, which may relate to injury vulnerability, and facilitate clinicians in selecting best-suited exercise interventions.

Long-standing pubic-related groin pain in professional academy soccer players: a prospective cohort study on possible risk factors, rehabilitation and return to play

Background

Despite being a common overuse entity in youth soccer, scientific data on risk factors, rehabilitation and return to play for long-standing pubic-related groin pain is still rare. The current prospective cohort study aims to evaluate potential risk-factors, propose a criteria-based conservative rehabilitation protocol and assess return-to-play outcomes among professional youth soccer players suffering from long-standing pubic-related groin pain.

Methods

Male soccer players with long-standing (> 6 weeks) pubic-related groin pain from a professional soccer club’s youth academy were analyzed for possible risk factors such as age, team (U12 - U23), younger/older age group within the team, position and preinjury Functional movement score. All injured players received a conservative, standardized, supervised, criteria-based, 6-level rehabilitation program. Outcome measures included time to return to play, recurrent groin pain in the follow-up period and clinical results at final follow-up two years after their return to play.

Results

A total of 14 out of 189 players developed long-standing pubic-related groin pain in the 2017/2018 season (incidence 7.4%). The average age of the players at the time of the injury was 16.1 ± 1.9 years. Risk factor analysis revealed a significant influence of the age group within the team (p = .007). Only players in the younger age group were affected by long-standing pubic-related groin pain, mainly in the first part of the season. Injured players successfully returned to play after an average period of 135.3 ± 83.9 days. Only one player experienced a recurrence of nonspecific symptoms (7.1%) within the follow-up period. The outcome at the 24-month follow-up was excellent for all 14 players.

Conclusions

Long-standing pubic-related groin pain is an overuse entity with a markedly high prevalence in youth soccer players, resulting in a relevant loss of time in training and match play. In particular, the youngest players in each team are at an elevated risk. Applying a criteria-based rehabilitation protocol resulted in an excellent return-to-play rate, with a very low probability of recurrence.

Trial registration

The trial was retrospectively registered under DRKS00016510 in the German Clinical Trials Register on 19.04.2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04837-x.

Field based lower limb strength tests provide insight into sprint and change of direction ability in academy footballers

Conducting field-based strength assessments is embedded within football academy development processes. Yet, there is a limited understanding of how hip and groin strength assessments relate to vital game-based tasks such as sprinting and change of direction (COD) performance. Our aim was to explore field-based strength assessments and their relationships with both sprint and COD performance in male academy footballers. Participants (n = 146; age 14.2 ± 2.2 years; stature 166.3 ± 15.4 cm; body mass 55.6 ± 15.6 kg) performed maximal countermovement jump (CMJ), Nordic hamstring strength (NHS), isometric hip adductor (ADD)/abductor (ABD), 5 m, 10 m, 20 m sprints, and modified 505 agility test. All strength measures were allometrically scaled to account for body weight. Between-limb differences were reported as imbalance scores. Principal component analysis reduced sprint and COD variables to a single "running ability" component score. Scaled strength and imbalance, when controlled for age, were associated with "running ability" (adjusted R²  = 0.78, p < 0.001). Significant effects on "running ability" included the following: age, CMJ impulse, NHS, and hip-ADD. When the sprint and COD variables were explored independently, age and CMJ-impulse were featured in all sprint and COD models. For 10 m and 20 m sprint distances, hip-ADD emerged as a significant effect. Mean 505 performance was explained by age, CMJ-impulse, hip-ADD, but also with the addition of NHS. Our findings suggest that insight into the underpinning strength qualities of "running ability" of academy footballers can be obtained from a suite of field-based tests.