Abstract
Background
Longitudinal monitoring of shoulder strength asymmetries in athletes is essential, as these imbalances are associated with reduced sports performance and increased injury risk. Tennis players, who frequently perform repetitive overhead motions, are particularly susceptible to strength discrepancies in the shoulder complex. Identifying and quantifying these asymmetries in elite youth tennis players can provide valuable insights for optimizing performance and reducing injury risk. This study aimed to examine longitudinal changes in shoulder strength asymmetries in elite youth tennis players.
Methods
Twelve elite youth tennis players (5 males, 7 females; mean age: 14.5 ± 1.8 years) underwent two isokinetic strength assessments, separated by a 12-month period, using a Biodex dynamometer. Measurements included peak torque, peak torque normalized to body weight (peak torque/body weight), and peak power for internal and external rotation at 90° shoulder abduction and a velocity of 60°/s. Asymmetry magnitudes were calculated using the percentage difference method: ((dominant value – non-dominant value/dominant value) * 100). Data normality was assessed with the Kolmogorov-Smirnov test. A repeated-measures ANOVA analysed changes in dominant and non-dominant internal and external rotation strength over time, separately for male and female players. Paired Samples t Tests examined changes in asymmetry magnitudes over time, with significance set at p < 0.05.
Results
All data were normally distributed. Strength measures were significantly higher (p < 0.05) in the dominant shoulder except for external rotation peak power, which showed no significant difference. Most strength metrics increased significantly over time, except for peak power/body weight in both internal and external rotation. Male players exhibited significantly greater internal and external rotation power than females. Asymmetry magnitudes ranged from 12.8% to 34.1%, with internal rotation asymmetry decreasing significantly over time, while external rotation asymmetry remained unchanged.
Discussion
These findings confirm the presence of significant shoulder strength asymmetries in elite youth tennis players, which evolve over time. Given the potential impact on performance and injury risk, targeted strength and conditioning programs are essential to address these imbalances. Due to the considerable variation in asymmetry magnitude, individualized assessments are recommended. Additionally, as the young age of participants precluded testing at higher angular velocities (e.g., 180°/s), future research should investigate whether significant asymmetries persist at greater angular speeds.
Longitudinal monitoring of shoulder strength asymmetries in athletes is essential, as these imbalances are associated with reduced sports performance and increased injury risk. Tennis players, who frequently perform repetitive overhead motions, are particularly susceptible to strength discrepancies in the shoulder complex. Identifying and quantifying these asymmetries in elite youth tennis players can provide valuable insights for optimizing performance and reducing injury risk. This study aimed to examine longitudinal changes in shoulder strength asymmetries in elite youth tennis players.
Methods
Twelve elite youth tennis players (5 males, 7 females; mean age: 14.5 ± 1.8 years) underwent two isokinetic strength assessments, separated by a 12-month period, using a Biodex dynamometer. Measurements included peak torque, peak torque normalized to body weight (peak torque/body weight), and peak power for internal and external rotation at 90° shoulder abduction and a velocity of 60°/s. Asymmetry magnitudes were calculated using the percentage difference method: ((dominant value – non-dominant value/dominant value) * 100). Data normality was assessed with the Kolmogorov-Smirnov test. A repeated-measures ANOVA analysed changes in dominant and non-dominant internal and external rotation strength over time, separately for male and female players. Paired Samples t Tests examined changes in asymmetry magnitudes over time, with significance set at p < 0.05.
Results
All data were normally distributed. Strength measures were significantly higher (p < 0.05) in the dominant shoulder except for external rotation peak power, which showed no significant difference. Most strength metrics increased significantly over time, except for peak power/body weight in both internal and external rotation. Male players exhibited significantly greater internal and external rotation power than females. Asymmetry magnitudes ranged from 12.8% to 34.1%, with internal rotation asymmetry decreasing significantly over time, while external rotation asymmetry remained unchanged.
Discussion
These findings confirm the presence of significant shoulder strength asymmetries in elite youth tennis players, which evolve over time. Given the potential impact on performance and injury risk, targeted strength and conditioning programs are essential to address these imbalances. Due to the considerable variation in asymmetry magnitude, individualized assessments are recommended. Additionally, as the young age of participants precluded testing at higher angular velocities (e.g., 180°/s), future research should investigate whether significant asymmetries persist at greater angular speeds.
| Original language | English |
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| Number of pages | 1 |
| Publication status | Published - 2025 |
| Event | European College of Sport Science congress 2025 - Italy, Rimini Duration: 1 Jul 2025 → 4 Jul 2025 |
Conference
| Conference | European College of Sport Science congress 2025 |
|---|---|
| City | Rimini |
| Period | 1/07/25 → 4/07/25 |