PMID 27900150

Research
All papers

Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO(2)max during exercise

Bagley L, Slevin M, Bradburn S, Liu D, Murgatroyd C, Morrissey G, Carroll M, Piasecki M, Gilmore WS, McPhee JS

Question

Do men and women respond differently to 12 weeks of very short-duration sprint interval training for body fat, fat oxidation, VO2max, and metabolic risk markers?

Summary

A 12-week sprint interval program with only 80 seconds of hard work per session improved VO2max and fat-oxidation capacity in adults. Men lost more fat mass, while women had a larger relative VO2max improvement; fasting glucose, insulin, HOMA-IR, triglycerides, total cholesterol, and HDL did not materially change.

Methodology

  • General adult men and women completing 12 weeks of low-volume sprint interval cycling.
  • 41 participants.
  • Cycle ergometer.
  • Work intervals: 20 s.
  • Recovery: 2 min very low-intensity cycling.
  • Intensity: Maximal effort at 175% of VO2max-test workload.
  • Less than 10 min.
  • 3 sessions/week.
  • 12 weeks.
  • Single-arm pre-post intervention with sex comparison
  • VO2max, Body fat, Fat oxidation, and Metabolic markers were tracked.

Outcomes

VO2max

VO2max increased overall, with a larger relative improvement in women.

Overall about +9%; women +18.7%, men +6.0%; sex x training p=0.009.

Improved

Fat mass

Fat mass decreased overall, with clearer loss in men than women.

Overall -1.0 kg; men lost more fat mass and percent body fat than women.

Mixed

Fat oxidation

FATmax improved similarly in men and women.

Approximately +13% improvement.

Improved

Glucose markers

Fasting glucose, insulin, and HOMA-IR did not significantly change.

Glucose p=0.496; insulin p=0.708; HOMA p=0.426.

No clear change

Lipids

LDL decreased and HDL:TC ratio improved, while triglycerides, total cholesterol, and HDL did not significantly change.

LDL -8%, p=0.028; HDL:TC +6%, p=0.005.

Mixed

Insights

  • Very low-volume sprint intervals can improve fitness with minimal hard-work time.
  • Body-fat and VO2max responses may differ by sex.
  • Do not overstate glucose-control improvements from this trial.

Limitations

  • No non-exercise control group
  • Moderate sample size for sex comparisons
  • Maximal sprint protocol
  • Diet and outside exercise were not tightly controlled
  • Not all sessions fully laboratory supervised

Safety

  • No explicit adverse-event results were reported.
  • Maximal sprint cycling was used, which limits direct translation to unscreened users.