Multivariate dynamic association analysis between sprint interval training and adolescent freestyle swimming performance
Question
Can complex network modeling describe the dynamic multivariate associations between a single 6 x 50 m sprint interval swimming session and 100 m freestyle performance in adolescent swimmers?
Summary
This cross-sectional sports science study tested 16 highly trained adolescent swimmers during a single 6 x 50 m maximal freestyle sprint interval session and a separate 100 m freestyle time trial. The researchers measured swimming velocity, stroke rate, stroke length, blood lactate, and RPE, then used complex network modeling to examine how these variables related to 100 m freestyle performance across the six sprint repetitions. Network structure stayed relatively stable, while velocity, lactate, and RPE became more central as fatigue accumulated; stroke rate became less central and stroke length stayed comparatively stable.
Methodology
- Sixteen highly trained adolescent freestyle swimmers with at least five years of formal swim training.
- 16 participants.
- Freestyle swimming.
- Work intervals: One 50 m maximal-effort freestyle sprint from wall push-off.
- Recovery: 4-minute inter-set rest.
- Intensity: Maximal effort.
- At least about 53 minutes including 20-minute warm-up, 10-minute rest, sprints, and rest intervals; exact duration not directly reported.
- Single testing session.
- Single session.
- Cross-sectional, exploratory complex network modeling study of one sprint interval session and one 100 m freestyle time trial.
- SSIT velocity, Blood lactate, RPE, and Stroke rate and stroke length were tracked.
Outcomes
SSIT physiological and perceptual load
During 6 x 50 m SSIT, mean velocity was 1.63 +/- 0.12 m/s, blood lactate was 12.15 +/- 1.48 mmol/L, RPE was 14.7 +/- 1.61, stroke rate was 44.11 +/- 2.86 cycles/min, and stroke length was 1.12 +/- 0.11 cycle/m. Lactate and RPE increased across the session.
Descriptive Table 1 values; no intervention p-values reported for these means.
100 m freestyle performance reference
Mean 100 m velocity was 1.68 +/- 0.11 m/s, blood lactate was 12.97 +/- 1.86 mmol/L, and RPE was 15.81 +/- 1.72.
Descriptive Table 1 values.
Network topology
Across sprint orders 1-6, networks showed stable high-density, low-modularity structure linking SSIT and 100 m freestyle variables.
Network density ranged from 0.426 to 0.492; modularity ranged from 0.198 to 0.243; number of nodes was 16 or 17 and edges 56-61.
Centrality of velocity, lactate, and RPE
Degree and eigenvector centrality for SSIT velocity, blood lactate, and RPE increased as sprint repetitions progressed, positioning them as central hubs in relation to 100 m freestyle performance.
Centrality trends reported from Fig. 5; exact numeric centrality values not provided in the paper.
Centrality of stroke variables
Stroke rate centrality declined, while stroke length influence remained relatively stable; the fourth 50 m may represent a turning point in technical parameters.
Centrality trends reported from Fig. 5 and discussion; exact numeric values not provided in the paper.
Insights
- This is athlete-performance evidence, not general consumer HIIT evidence.
- In repeated maximal sprint intervals, later repetitions may reveal rising metabolic and perceptual load while technical variables shift under fatigue.
- For app translation, pace/velocity and RPE are more practical monitoring signals than blood lactate or network centrality.
Limitations
- Small sample of 16 adolescent swimmers
- Highly trained and sport-specific population
- Cross-sectional single-session design
- No control group and no long-term training adaptation
- Freestyle swimming only
- Complex network analysis is exploratory and does not infer causality
Safety
- No adverse events or injuries were reported in the paper.
- Participants were screened for good health and absence of recent cardiopulmonary disease or musculoskeletal injury.
- Tests were separated by 48 hours and preceded by standardized warm-up and rest.