ExerciseInterval Training

Is high intensity interval training better than regular training?

Bottom Line:

This was a meta-analysis looking at studies comparing high-intensity interval training (HIIT) and regular or moderate intensity continuous training (MICT).  In treadmill running, the authors found that both HIIT and MICT resulted in ~2.6kg of fat loss.  This is equivalent to ~10% drop in body fat from baseline.  Although both groups achieved similar results, the HIIT group required 40% LESS time. Thus, interval training may be very time efficient way to achieve the same results as continuous training.

Why this matters:

One of the most commonly cited barriers to exercise has always been lack of time.  High-intensity interval training (HIIT) offers a unique way to achieve the same results as regular treadmill running but with 40% less time. HIIT can be done by having short periods of intense exercise with less intense recovery periods. For example, sprint for 30 seconds and then slow down to a moderate pace for another 30 seconds.

Study Design:

This was a systematic review and meta-analysis of 13 studies. Studies averaged roughly 10 weeks and included 3 sessions per week. The 424 participants were overweight or obese individuals ages 18-45 years. The participants did not have any other medical problems such as diabetes, high blood pressure or heart disease.

Key findings:

  • Body fat decreased 1.7kg for HIIT and 2.1kg for MICT
  • Waist Circumference decreased 3cm for both HIIT and MICT
  • Body weight decreased 2kg for HIIT and 1.9kg for MICT. This was not significant.
  • Sub-analysis showed that only running produced significant reduction in body fat and waist circumference. Cycling did not produce any significant effects.
  • Dropout rate was 16% for HIIT and 20% for MICT

Limitations:

  • The individual studies had small sample sizes.
  • The participants were healthy. It would be interesting to see if the results are the same in participants with diabetes.
  • There was a high dropout rate but interestingly it was lower in the HIIT group versus MICT group

Reference:

Wewege, M., van den Berg, R., Ward, R. E., and Keech, A. (2017) The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Obesity Reviews, 18: 635–646. doi: 10.1111/obr.12532.

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Dr. Sean

Sean Hashmi, MD, MS, FASN is a practicing Nephrologist and Obesity Medicine Specialist in Southern California. He is founding director of SELFPrinciple.org, a non-profit, non-commercial site focused on evidence based nutrition, health, and wellness.
Dr. Hashmi graduated from the University of California, San Diego Medical School. He completed his residency in Internal Medicine at UCLA-Olive View Medical Center followed by a fellowship in Nephrology at the University of California, Los Angeles.

  • Ray Nanda

    Fascinating. Thanks Dr Sean!!

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