High-intensity swim training improves fitness and short-event performance in competitive swimmers, but its value for 1.9-3.8 km triathlon swims is untested
Interpretation
For competitive pool swimmers the evidence is reasonably consistent: a meta-analysis of 11 studies (237 swimmers, mean age 15.4) found HIIT improved VO2max and performance, especially in sprint events and after 8 weeks or more; replacing half the volume with HIT neither helped nor harmed 100-200 m times in 41 elite swimmers (Kilen 2014) or 100-400 m times over 4 weeks (Faude 2008); a review found no harm in 7 studies. But participants were mostly young sprint and middle-distance swimmers, USRPT has no eligible trials, and the only triathlete study (32 amateurs, 4 weeks) found intensity- and volume-based training improved 50 m and 400 m equally. Graded limited for long-course triathletes because of this population and distance gap.
Practical implication
Long-course triathletes can use short, fast repeats and some higher-intensity sets as a time-efficient part of the week, alongside threshold and steady aerobic swimming and technique work. Benefits for 1.9 km and 3.8 km open-water swims are extrapolated from short pool events in young swimmers.
Sources
6 sources, independently verified.
HIIT improved VO2max (SMD 0.86) and swimming performance (SMD 0.52); largest gains in sprint events (1.8%); interventions of 8 weeks or more had larger effects (SMD 0.78 vs 0.42); ultra-short race-pace training held 98.5% of target speed with 24% lower lactate. For 800 m and longer, only preliminary support for pyramidal approaches. Mostly adolescent pool swimmers.
Both groups trained about 12 h/week for 12 weeks; the HIT group swam about 17 km/week with about 5 h of HIT (6-10 x 10-30 s maximal efforts) versus about 35 km/week with 1 h HIT. 100 m and 200 m performance and absolute VO2max were unchanged in both groups. Authors speculate HIT could be detrimental beyond 800 m (untested).
Two 4-week periods of high-volume or lower-volume high-intensity training, each followed by a taper week. 100 m and 400 m times were not significantly affected by training type; high volume had no advantage over high intensity over 4 weeks.
Of 538 records, 7 studies compared HIT (at least 4 weeks) with higher-volume training. HIT improved physiological measures in 6 and swimming performance in 4; none found a reduction. Short study durations limit conclusions.
Screened 1,347 records and 15 full texts but found no eligible trials of USRPT as defined. Concludes USRPT is not grounded in peer-reviewed research and its recommendations to avoid resistance training, cross-training, sub-race-pace swimming and part-practice drills are highly controversial; notes 1,500 m and 10 km events depend on aerobic supply.
Four weeks of intensity- or volume-based training (6 sessions/week) both improved 50 m and 400 m swim times; no difference between them in 2000 m run, HRV, jump or body composition. Short study; swim tests no longer than 400 m.