PMID 29707918

Research
All papers

High intensity interval training and vitamin D3 supplementation in overweight and obese adults

Lithgow HM, Florida-James G, Leggate M

Question

Does vitamin D3 supplementation augment glycemic, cardiometabolic, and fitness adaptations to 6 weeks of HIIT in overweight and obese adults?

Summary

In overweight and obese but otherwise healthy adults, 6 weeks of supervised cycling HIIT improved aerobic fitness, waist/hip measures, systolic blood pressure, triglycerides, and glucose and insulin responses during an oral glucose tolerance test. Daily vitamin D3 corrected low vitamin D status but did not add metabolic benefit and appeared to blunt the glucose AUC improvement.

Methodology

  • Overweight or obese Caucasian adults, otherwise healthy and recreationally inactive/lightly active
  • 20 participants.
  • Stationary cycling.
  • Work intervals: 1 minute.
  • Recovery: 1 minute active recovery at 50 W.
  • Intensity: 100% VO2peak workload for sessions 1-6, 110% for sessions 7-12, 120% for sessions 13-18.
  • 30 minutes including 5-minute warm-up and 5-minute cool-down.
  • 3 sessions per week.
  • 6 weeks; 18 sessions.
  • Randomized, double-blind, placebo-controlled supplementation trial with all participants completing supervised HIIT
  • VO2peak, Glucose AUC, Insulin AUC, and Triglycerides were tracked.

Outcomes

VO2peak

VO2peak increased by 12% and peak power increased by 17% across participants, without added effect of vitamin D3.

VO2peak P < 0.001; peak power P < 0.001

Improved

OGTT glucose

Glucose AUC improved overall, but the improvement occurred mainly in placebo and was attenuated in the vitamin D3 group.

Glucose AUC 829 +/- 110 to 786 +/- 139 mmol h/L, P = 0.043; group x time interaction P = 0.035

Mixed

OGTT insulin

Insulin AUC decreased after HIIT.

8101 +/- 4755 to 7024 +/- 4489, P = 0.049

Improved

Triglycerides

Triglycerides decreased after the intervention.

1.93 +/- 1.06 to 1.72 +/- 1.04, P = 0.025

Improved

Blood pressure

Systolic blood pressure decreased by about 6 mmHg.

P = 0.004

Improved

Insights

  • A 10 x 1-minute cycling format with equal active recovery was feasible under supervision in overweight/obese adults.
  • Progressing from 100% to 120% of VO2peak workload produced fitness and cardiometabolic changes over 6 weeks.
  • Vitamin D3 supplementation should not be presented as an enhancer of HIIT glycemic adaptations based on this small trial.

Limitations

  • Small sample size and limited power for subgroup or interaction effects.
  • All participants exercised, so HIIT effects are primarily pre-post rather than compared with a non-exercise control.
  • Diet was not tightly controlled or monitored.
  • Post-testing 72 hours after the final session may miss acute exercise effects.

Safety

  • No adverse events or injuries were reported in the article. Safety/context details reported: participants were otherwise healthy and screened by exclusions, HIIT was supervised with HR and RPE monitoring, 20/22 completed, 2 withdrew for time commitments, HIIT adherence was 99.4%, and supplement/placebo compliance was 100%.