Ryan Keating

Elite 50 m freestyle performance demands targeted interventions for events that may be decided by hundredths of a second. This case study assesses the effectiveness of an individualised in-water resistance training intervention informed by load–velocity (LV) profiling in both profiling metrics and competitive performance, while documenting the training characteristics of an elite 50 m freestyle swimmer (male, 24.8 years) over the 18 months culminating in the Paris 2024 Olympic Games. A coach-led, six-week resisted-swim intervention involved three sessions per week with prescribed velocity-decrement zones targeting technical development, speed-strength, and power while preserving the swimmer’s race stroke rate. Post-intervention LV outputs showed likely improvements in maximal swim speed, of +3.4% and theoretical maximal load, of +13.6%, and competition time improved by 1.3% with a 3.5% improvement in free swimming time (15–45 m). Although limited to a single-athlete design, the observed improvements suggest that individualised, LV-informed resisted swimming using accessible equipment may contribute to enhancements in sprint swimming performance.

This study investigated the relationship between sprint swim performance and outputs derived from fully-tethered and semi-tethered swimming assessments in high-performance male and female swimmers. Twenty elite/highly trained swimmers (9 females, 11 males), specialising in 50-100 m events, completed all assessments in a randomised order in a 25 m pool. 50 m time-trial variables included total time, stroke rate, stroke length and swim velocity. A fully-tethered protocol involved 20 s of maximal swimming to determine peak and mean force, impulse and stroke rate. A semi-tethered protocol required swimmers sprinting 10 m with incremental loads (1, 3, 5 kg for females; 1, 5, 9 kg for males). Load-velocity and force-velocity profiling derived theoretical maximum velocity (V₀), theoretical maximal load/force (L₀/F₀), relative to body mass (rL₀/rF₀) and absolute and relative slope between the two variables. All semi-tethered variables except slopes showed large to extremely large correlations with 50 m total time (r = -0.618 to -0.955, p < 0.05) in males and females. In contrast, fully-tethered variables showed heterogeneous correlations, suggesting stroke- and sex-specific analyses may be more appropriate. These findings highlight semi-tethered profiling as an effective and ecologically valid tool for assessing sprint performance in high-performance swimmers and informing targeted training interventions.

The study compares three methods of evaluating semi-tethered performance in front crawl swimming using different velocity extraction techniques. Thirty Level 4 swimmers (17 males, 13 females) completed three protocols: Absolute (5 × 25 m, 1-9 kg for males; 1-5 kg for females), Modified (3 × 10 m, 1, 5, 9 kg for males; 1, 3, 5 kg for females) and Velocity-Restricted (device limited to 1 m/s), across three testing sessions, 7 days apart. Absolute and Modified protocols generated load-velocity (LV) and force-velocity (FV) profiles, while Velocity-Restricted produced an FV profile to determine maximal velocity (LV-V₀, FV-V₀), absolute and relative load/force (L₀, F₀, rL₀, rF₀) and slope (S_LV, S_FV). Reliability estimates for the Absolute method: ICC 0.74-0.83, CV% 2.4-9.0% for males; ICC 0.57-0.87, CV% 2.4-11.6% for females. Modified: ICC 0.51-0.85, CV% 2.8-13.7% for males; ICC 0.16-0.80, CV% 2.9-17.1% for females. Velocity-Restricted: ICC 0.50-0.84, CV% 2.6-8.5% for males; ICC 0.10-0.55, CV% 4.2-21.7% for females. FV-V₀ was significantly higher than LV-V₀ (p < 0.001), showing LV and FV outputs are not interchangeable. No statistical differences between Absolute and Modified protocols suggest that the latter (5 m analysis) is a more time-efficient method. Differences in reliability highlight the need for sex-specific considerations when interpreting results.

Load-velocity (LV) profiling in swimming provides key metrics, including theoretical maximal velocity (V₀) and theoretical maximal load (L₀); however, longitudinal studies tracking these variables across competitive seasons are limited. This study investigated LV profiling and competition performance in national and international-level swimmers (Level 1–3) over a 15-month period. Twenty-six swimmers participated (16 males: age: 19.8 ± 3.9 years, body mass: 80.3 ± 7.9 kg, height: 1.84 ± 0.07 m; 10 females: age: 20.7 ± 3.6 years, body mass: 68.2 ± 5.7 kg, height: 1.74 ± 0.03 m), all specializing in 50–200 m events. Swimmers completed 4–6 testing sessions, each involving 3 × 10 m sprints against resistances of 1, 5, and 9 kg (males) and 1, 3, and 5 kg (females), in both front-crawl and their preferred-stroke. Linear mixed-effects models assessed changes in LV outputs—V₀, L₀ (absolute and relative to body mass), relative slope (−V₀/rL₀), and active drag (AD). Smallest worthwhile change (SWC) assessed within-athlete variation, while Pearson's correlations evaluated relationships between race performance and LV outputs. Analysis of preferred-stroke found males exhibited significantly higher values across all variables except the slope (p = 0.607). National-level swimmers had lower L₀ (−2.8 kg, p = 0.019), but no statistical difference in rL₀ (−1.5%, p = 0.244) or slope (−0.002 m/s/%, p = 0.558). AD remained stable across observations, though males produced greater drag (+30.2 N, p < 0.001), while national-level swimmers produced less (−12.8 N, p = 0.045). Analysis of front-crawl performance found males presented higher values across all variables (p ≤ 0.05) while national-level swimmers were lower (p < 0.005). SWC analysis revealed that most within-athlete changes in V₀ and L₀ were trivial or unclear, with only isolated meaningful changes observed. Large to very large correlations existed between race performance and L₀ (r = 0.67, p < 0.05), V₀ (r = 0.73, p < 0.05), and AD (r = 0.58–0.7, p < 0.05) at select observations. These findings highlight the stability of LV profiling metrics over time while reinforcing their relevance in distinguishing between performance levels. This suggests their potential utility in talent identification and informing training prescription.