PMID 34110721

Research
All papers

Effects of sprint interval training on substrate oxidation in adults living with and without obesity: The i-FLEX study

Colpitts BH, Seaman K, Eadie AL, Brunt KR, Bouchard DR, Sénéchal M

Question

Does 4 weeks of sprint interval training alter resting or exercise substrate oxidation differently in adults living with and without obesity?

Summary

After 4 weeks of supervised Wingate-style sprint interval training, adults with obesity showed lower submaximal exercise RER and higher submaximal fat oxidation, while adults without obesity did not show the same substrate shift. The study was small, single-arm, and lacked a non-exercise control group.

Methodology

  • Adults with and without obesity completing 4 weeks of supervised SIT.
  • 34 participants.
  • Stationary cycling.
  • Work intervals: 30 s.
  • Recovery: 4 min active recovery at 59 W.
  • Intensity: All-out Wingate at 7.5% bodyweight load.
  • 9-18 min plus cooldown.
  • 3 sessions/week.
  • 4 weeks.
  • Single-arm quasi-experimental intervention with obesity-status comparison
  • Submaximal RER, Submaximal fat oxidation, Insulin sensitivity, and VO2peak were tracked.

Outcomes

Submax RER

Adults with obesity reduced submaximal RER after SIT.

Obesity 0.95 +/- 0.08 to 0.92 +/- 0.06; time x group p=0.001.

Improved

Fat oxidation

Submaximal fat oxidation increased in adults with obesity.

105.5 to 208.0 g/min; p=0.009.

Improved

Insulin sensitivity

Insulin sensitivity decreased in the no-obesity group and increased nonsignificantly in the obesity group.

Group x time p=0.033.

Mixed

VO2peak

VO2peak improved in the no-obesity group but not significantly in the obesity group.

No-obesity p=0.004; obesity p=0.352.

Mixed

Insights

  • SIT may change fuel use during exercise in adults with obesity, but this is mechanistic evidence.
  • Long recoveries and screening are central to the studied sprint protocol.
  • Do not translate Wingate SIT directly to broad unsupervised bodyweight workouts.

Limitations

  • No non-exercise control group
  • Small sample
  • Short intervention
  • Different activity eligibility by obesity status
  • VO2peak rather than VO2max
  • Prior training experience not recorded

Safety

  • Three participants dropped out for injury/illness unrelated to the intervention or personal reasons.
  • HR and BP were checked after cooldown before participants left sessions.