PMID 40755811

Research
All papers

Influence of 4-week lower extremity high-intensity interval training on energy metabolism and maximal oxygen uptake of elite swimmers

Jin R, Sun J, Jiang N, Chen C

Question

Does a 4-week dry-land lower-limb HIIT program improve energy metabolism and VO2max in elite swimmers compared with regular training?

Summary

In elite swimmers, 4 weeks of supervised dry-land lower-limb HIIT improved absolute phosphagen, glycolytic, aerobic, and total energy supply and VO2max compared with regular training alone. The sample was small and limited to elite swimmers from one institution.

Methodology

  • Elite competitive swimmers from Shanghai University of Sport.
  • 24 participants.
  • Dry-land lower-limb circuit including high leg lift, elastic band drills, BOSU squat jumps, squat jumps, slide board, side jumps, and resisted jumps.
  • Work intervals: 20 seconds.
  • Recovery: 10 seconds.
  • Intensity: Maximal intensity for each exercise.
  • About 60 minutes including 20-minute warm-up, 30-minute HIIT work, and 10-minute stretching/relaxation.
  • 3 sessions per week.
  • 4 weeks.
  • Randomized controlled pre/post intervention.
  • Energy supply, and VO2max were tracked.

Outcomes

Energy supply

HIIT significantly increased absolute phosphagen, glycolytic, aerobic, and total energy supply while controls did not.

HIIT total energy supply 214.48 ± 38.58 to 290.65 ± 42.01 kJ; group × time F = 101.979, p < 0.001, η2 = 0.823.

Improved

Energy proportions

Relative contribution percentages of energy pathways did not significantly change.

Phosphagen %, glycolytic %, anaerobic %, and aerobic % all p > 0.05.

No clear change

VO2max

VO2max improved in the HIIT group and did not improve in controls.

HIIT 51.48 ± 3.85 to 55.03 ± 4.90 ml/min/kg; time p = 0.041; group p = 0.009; time × group p < 0.001.

Improved

Insights

  • A short dry-land lower-limb HIIT block may improve metabolic output and VO2max in already highly trained swimmers.
  • The 20:10 structure is highly specific and supervised; it should not be treated as general home-fitness evidence.
  • The study supports sport-specific lower-limb power programming more than general public HIIT guidance.

Limitations

  • Small sample from one institution.
  • Elite swimmers only.
  • Menstrual cycle phase of female athletes was not monitored or controlled.
  • Neuromuscular activity and lactate clearance mechanisms were not directly measured.
  • Performance outcomes in the pool were not reported.

Safety

  • One screened athlete was excluded due to injury risk before enrollment.
  • All 24 enrolled athletes completed the intervention and post-testing.
  • The article did not report adverse events during the intervention.