An interventional study of Reduced-Volume High-Intensity Interval Swimming Training and Higher-Volume Moderate-Intensity Swimming Training in Physical Disability, Intellectual Impairment and Athletic Performance, sponsored by National and Kapodistrian University of Athens. Completed at 1 site in Greece. Open to participants aged 12 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-07.
Sponsored by National and Kapodistrian University of Athens · Not applicable, Interventional, and Other
This study compared the effects of four weeks of reduced-volume high-intensity interval training and higher-volume moderate-intensity swimming training on repeated-sprint ability, physiological responses, and body composition in competitive para swimmers. Twenty-four national-level swimmers representing World Para Swimming sport classes S5-S10 and S14 were randomly allocated to one of the two training interventions by drawing sealed group assignments. Both groups completed two supervised sessions per week for four weeks. Repeated-sprint ability was assessed before and after the intervention using eight maximal 15-m freestyle sprints.
Competitive para swimmers with physical or intellectual impairments were purposively recruited to provide representation across the included World Para Swimming sport classes. After enrollment and baseline assessment, participants were randomly allocated to reduced-volume high-intensity interval training or higher-volume moderate-intensity training by drawing sealed group assignments. The study used a two-arm, randomized, parallel-group, active-comparator design.
Both interventions lasted four weeks and included two supervised swimming sessions per week. The high-intensity intervention used lower-volume maximal and near-maximal swimming efforts, whereas the active-comparator intervention used a higher volume of moderate-intensity swimming.
Repeated-sprint ability was evaluated using eight maximal 15-m freestyle sprints separated by a standardized 30-s interval. The interval began when the swimmer crossed the 15-m timing marker and included a controlled low-intensity 6-m return to the wall followed by stationary in-water recovery. Repeated-sprint outcomes included ideal sprint time, total sprint time, and performance decrement. Physiological responses and body-composition measures were also obtained before and after the training intervention.
National and Kapodistrian University of Athens is the lead sponsor of 172 studies on the registry; 52 are open to participants now.
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Classified in Para Swimming sport class S5, S6, S7, S8, S9, S10, or S14. At least 12 years of age. Active competitive swimmer participating at the national level. Had won at least one national championship medal during the preceding two competitive seasons.
Regularly participating in organized swimming training. Able to understand and complete the adapted repeated-sprint swimming protocol. Provided written informed consent; for minors, consent was provided by a parent or legal guardian, and assent was obtained where applicable.
Exclusion Criteria:
Medical contraindication to maximal-intensity swimming exercise. Acute illness or injury preventing participation in testing or training. Change in medication or health status expected to influence exercise responses. Failure to complete the required familiarization, baseline testing, or intervention sessions.
Participation in another intervention likely to affect the study outcomes.
Participants completed two supervised sessions per week for four weeks. The main training sets incorporated high-intensity or maximal swimming efforts and had approximately 50% less training volume than the main sets completed by the higher-volume group.
Behavioral: Reduced-Volume High-Intensity Interval Swimming Training
The active-comparator intervention lasted four weeks and included two supervised sessions per week. Participants completed 50-, 100-, and 200-m freestyle intervals at moderate intensity using the predefined work-to-recovery structure. Intensity was monitored using heart rate and rating of perceived exertion, targeting approximately 60%-75% of estimated maximum heart rate and ratings of 3-4 on the Borg CR10 scale. Main-set volume was approximately 50% greater than in the high-intensity intervention.
Behavioral: Higher-Volume Moderate-Intensity Swimming Training
The intervention lasted four weeks and included two supervised sessions per week. Main-set activities included intermittent 50-m swims with short recovery intervals, 25-m all-out sprints using a 1:1 work-to-recovery ratio, and five 30-s tethered maximal efforts with 2 min 30 s of recovery between efforts. The precise session content progressed according to the predefined training schedule.
The active-comparator intervention lasted four weeks and included two supervised sessions per week. Participants completed 50-, 100-, and 200-m freestyle intervals at moderate intensity using the predefined work-to-recovery structure. Intensity was monitored using heart rate and rating of perceived exertion, targeting approximately 60%-75% of estimated maximum heart rate and moderate intensity ratings (e.g., 3-4) on the Borg CR10 scale. Main-set volume was approximately 50% greater than in the high-intensity intervention.
Change in Total Sprint Time
Total sprint time, measured in seconds, was calculated as the sum of the eight 15-m maximal freestyle sprint times. Lower values indicate better overall repeated-sprint performance.
Time frame: Baseline and two days after the final training session at four weeks
Change in Ideal Sprint Time
Ideal sprint time, measured in seconds, was calculated as the fastest single 15-m sprint time multiplied by eight. Lower values indicate better performance.
Time frame: Βaseline and two days after the final training session at four weeks
Change in Performance Decrement
Performance decrement was calculated as \[(total sprint time / ideal sprint time) × 100\] - 100 and expressed as a percentage. Lower values indicate less performance loss across the eight sprint repetitions
Time frame: Βaseline and two days after the final training session at four weeks
Change in 50-m and 200-m Freestyle Performance
Swimming performance is evaluated by the time (in seconds) required to complete 50-m and 200-m maximal freestyle tests. Lower values indicate better performance.
Time frame: Baseline and two days after the final training session at four weeks
Change in Stroke Rate
Stroke Rate (cycles/min) was assessed via video analysis during the swimming efforts.
Time frame: Baseline and two days after the final training session at four weeks
Changes in Stroke Length
Stroke Length (m/cycle) was assessed via video analysis during the swimming efforts.
Time frame: Βaseline and two days after the final training session at four weeks
Change in heart rate
Physiological markers were assessed pre- and post-exercise, including heart rate (beats/min).
Time frame: Baseline and two days after the final training session at four weeks
Change in blood lactate concentration
Physiological markers were assessed pre- and post-exercise, including blood lactate concentration (mmol/L).
Time frame: Βaseline and two days after the final training session at four weeks
Change in oxygen saturation
Physiological markers were assessed pre- and post-exercise, including oxygen saturation (%).
Time frame: Βaseline and two days after the final training session at four weeks
Change in fatigue index
Physiological markers were assessed pre- and post-exercise, including the fatigue index.
Time frame: Βaseline and two days after the final training session at four weeks
Change in VO2peak
Physiological markers were assessed pre- and post-exercise, including VO2peak.
Time frame: Βaseline and two days after the final training session at four weeks
Change in body mass
Body composition changes, including body mass (kg).
Time frame: Baseline and two days after the final training session at four weeks
Change in body-fat percentage
Body composition changes, body-fat percentage (%).
Time frame: Baseline and two days after the final training session at four weeks
Plan to share: No — Individual participant data are not planned for public release because the small sample size and detailed sport-class information may create a risk of participant re-identification. De-identified aggregate data and additional study information may be available from the corresponding author upon reasonable request and subject to ethical and institutional approval.
Ran from Sep 2022 to primary completion in Nov 2022, 2 months.
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