PMID 29855444

Research
All papers

High intensity interval training is associated with greater impact on physical fitness, insulin sensitivity and muscle mitochondrial content in males with overweight/obesity, as opposed to continuous endurance training: a randomized controlled trial

De Strijcker D, Lapauw B, Ouwens DM, Van de Velde D, Hansen D, Petrovic M, Cuvelier C, Tonoli C, Calders P

Question

Does 10 weeks of low-volume high-intensity interval training produce stronger metabolic and mitochondrial adaptations than continuous aerobic training in overweight/obese men at risk for type 2 diabetes?

Summary

In sedentary middle-aged men with overweight or obesity and diabetes risk, 10 weeks of twice-weekly high-intensity cycling improved peak fitness, insulin-sensitivity measures, basal respiratory exchange ratio, and muscle mitochondrial content more than a matched-duration continuous aerobic program. The trial was very small and the two exercise modes were not calorie-matched.

Methodology

  • Sedentary males aged 42-57 years with BMI 28-36 kg/m2 and HbA1c below diabetes threshold.
  • 16 participants.
  • Cycling intervals with continuous aerobic segment.
  • Work intervals: 15 s.
  • Recovery: 45 s.
  • Intensity: 100% ventilatory-threshold resistance for weeks 1-5, 110% weeks 6-10; HR >85% peak HR.
  • 40 min.
  • 2 sessions/week.
  • 10 weeks.
  • Randomized controlled two-arm exercise trial
  • Peak VO2, Insulin sensitivity, Basal respiratory exchange ratio, and Muscle mitochondria were tracked.

Outcomes

Peak VO2

Peak VO2 improved after HIT but not continuous aerobic training.

HIT p=0.023; time x group p=0.004.

Improved

Insulin sensitivity

Glucose AUC, insulin AUC, and OGTT composite score improved more after HIT.

AUC glucose and insulin time x group p<0.001; OGTT composite time x group p=0.005.

Improved

Basal RER

Basal RER decreased after HIT, consistent with greater fasting fat oxidation.

HIT p=0.001; CAT p=0.37; time x group p<0.001.

Improved

Mitochondria

Mitochondrial number and surface area increased after HIT at intermyofibrillar and subsarcolemmal sites.

Intermyofibrillar number p<0.001 and surface p=0.001; subsarcolemmal number p=0.004 and surface p=0.001.

Improved

Safety

No adverse events were reported during training sessions.

No clear change

Insights

  • Short 15/45 cycling intervals can produce metabolic adaptations with only two sessions per week when intensity is individualized.
  • Clinical-risk users need screening and supervision before high-intensity cycling.
  • Claims about insulin sensitivity should acknowledge this was a small all-male trial.

Limitations

  • Very small sample
  • All participants were male
  • Protocols were not eucaloric
  • Baseline insulin sensitivity differed between groups
  • OGTT insulin was not measured immediately after the test

Safety

  • No adverse events were reported during training sessions.
  • One HIT participant attended 18 of 20 sessions because of injury, without detail tying it to training.