Author(s): TOUBEKIS, A., CHALKIADAKIS, I., NIKITAKIS, I., ARSONIADIS, G., Institution: NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS, Country: GREECE, Abstract-ID: 1003

INTRODUCTION:
In-water force applied during tethered swimming is a key determinant of swimming performance. In age-group swimmers, biological maturation plays a critical role in the development of strength and power, particularly in male athletes [1]. Previous research has demonstrated associations between dry-land strength and power with in-water tethered force and impulse [2]; however, limited evidence exists regarding how these in-water kinetic variables evolve across maturation stages in competitive swimming. Therefore, the purpose of the present study was to examine age- and sex-related differences in tethered force, impulse, and fatigue index across age-group categories in competitive swimmers.
METHODS:
A total of 197 competitive swimmers (127 males and 70 females; age: 15.0 ± 3.1 years; body height: 164.4 ± 13.3 cm; body mass: 58.3 ± 14.0 kg) participated in a single session of a maximum effort 30 s tethered swimming test. Participants were classified into eight age-groups based on chronological age: A1 (10.0–10.99 years), A2 (11.0–11.99 years), A3 (12.0–12.99 years), A4 (13.0–13.99 years), A5 (14.0–14.99 years), A6 (15.0–15.99 years), A7 (16.0–16.99 years), and A8 (≥17 years). Mean tethered force (TF), force per second and force per arm-stroke were recorded. Impulse (IMP) was calculated as the product of force and the duration of the underwater phase of each arm-stroke. The fatigue index (FI) was calculated using the formula: FI% = [(maxTF − minTF) / maxTF] × 100, where maxTF and minTF were the mean TF in the first and last 5 s, of the 30 s test respectively.
RESULTS:
An interaction between sex and age-group was observed for mean TF (p = 0.01). In male swimmers, TF was lower in A1 (38.2 ± 6.6 N) compared to A5 (80.0 ± 19.3 N), A6 (90.2 ± 16.0 N), A7 (95.0 ± 16.4 N), and A8 (114.0 ± 23.2 N). In female swimmers, TF was lower in A1 (40.5 ± 4.1 N) compared to A4 (69.2 ± 8.9 N) and A5 (67.9 ± 10.9 N).
Similarly, a sex-by-age-group interaction was found for mean IMP (p = 0.01). Male swimmers demonstrated lower IMP values in A1 (23.1 ± 3.9 N·s) compared to A5 (47.8 ± 13.3 N·s), A6 (51.5 ± 12.0 N·s), A7 (54.8 ± 11.4 N·s), and A8 (65.5 ± 13.5 N·s). In female swimmers, IMP was lower in A1 (24.5 ± 3.8 N·s) compared to A4 (41.6 ± 5.5 N·s), A5 (41.4 ± 6.2 N·s), and A8 (50.7 ± 9.5 N·s). FI was similar across chronological age categories (p = 0.82), while female swimmers presented a lower FI than male swimmers (Females: 26.3 ± 7.9% vs. Males: 30.8 ± 7.1%, p = 0.01).
CONCLUSION:
In-water TF and IMP increase progressively with age, likely reflecting maturation-related adaptations. The fatigue index did not vary across age categories, but females consistently had lower values than males, indicating sex-specific differences in fatigue resistance. These findings highlight the importance of considering age- and sex-specific kinetic characteristics when designing training and monitoring performance development in competitive swimming.
1. Costa et al., 2021; 2. Loturco et al., 2015