PMID 33467257

Research
All papers

The Effects of Short-Term High-Intensity Interval Training and Moderate Intensity Continuous Training on Body Fat Percentage, Abdominal Circumference, BMI and VO(2max) in Overweight Subjects

Russomando L, Bono V, Mancini A, Terracciano A, Cozzolino F, Imperlini E, Orrù S, Alfieri A, Buono P

Question

Does a 6-week, 3-days-per-week personalized supervised HIIT protocol improve body fat percentage, abdominal circumference, BMI, and VO2max compared with standard MICT in young overweight sedentary adults?

Summary

This small randomized trial compared six weeks of supervised personalized HIIT plus resistance training with a longer MICT plus resistance-training program in young overweight sedentary adults. Both groups improved body composition and estimated VO2max, with no significant training-by-time interaction. A secondary comparison of percent changes favored HIIT for VO2max and showed only a trend for greater fat-mass reduction. The protocol is useful for HIIT Play as a time-efficient, equipment-based interval template, but the evidence is limited by small sample size, estimated VO2max, and combined resistance training.

Methodology

  • Young healthy overweight sedentary volunteers performing less than 60 minutes of exercise 1-2 times per week
  • 20 participants.
  • Machine resistance training followed by jump-box/stepper interval training.
  • Work intervals: 30 seconds at 140% of maximum workload, targeting HR up to 90% predicted HRmax.
  • Recovery: 90 seconds active recovery at 25% of maximum workload, targeting HR up to 60% predicted HRmax.
  • Intensity: Personalized from YMCA-adapted test; HRmax predicted with Tanaka equation; resistance training at approximately 70% 1RM.
  • 40 minutes: 6-minute warmup, 20-minute RT, 8-minute HIIT, 6-minute cooldown.
  • 3 days/week.
  • 6 weeks.
  • Randomized controlled trial with pre/post assessments
  • BMI, Body fat percentage, Abdominal circumference, and VO2max were tracked.

Outcomes

Training completion

Seventeen of 20 participants completed training; the three dropouts were in the MICT group. HIIT and MICT participants who remained completed a similar number of sessions.

HIIT 17.6 +/- 0.5 sessions; MICT 17.1 +/- 0.7 sessions out of 18; p=0.103.

Improved

Training-related injury

No training-related injury was reported.

No clear change

BMI, body fat percentage, abdominal circumference, VO2max

Both HIIT and MICT improved the tested health-related parameters over time, but two-way ANOVA did not show a significant training-by-time interaction for any parameter.

Training x time interaction p>0.05 for all parameters.

Improved

VO2max percent change

Percent-change comparison favored HIIT for estimated VO2max.

Delta mean percentage: MICT +3.2% vs HIIT +5.7%; p=0.05.

Improved

Fat mass percent change

Percent-change comparison showed a trend toward greater fat-mass percentage reduction with HIIT, but it did not meet conventional significance.

Delta mean percentage: MICT -5.7% vs HIIT -8.2%; p=0.06.

Mixed

BMI and abdominal circumference percent change

Percent-change comparisons did not favor HIIT over MICT for BMI or abdominal circumference.

BMI: MICT -4.3% vs HIIT -3.4%, p=0.28; abdominal circumference: MICT -1.6% vs HIIT -1.1%, p=0.30.

No clear change

Insights

  • A very small total hard-work dose, 2 minutes per session, can be embedded in a 40-minute resistance-plus-HIIT workout and still target high intensity.
  • Compared with a 60-minute MICT-plus-RT protocol, this 40-minute HIIT-plus-RT protocol produced similar broad improvements and a stronger VO2max percent-change signal in a small sample.
  • Body-composition claims should be cautious: the key fat-mass comparison was a trend, and the training-by-time interaction was not significant.
  • Combining HIIT with resistance training is product-relevant for workout design but complicates attribution of outcomes to HIIT alone.

Limitations

  • Small sample size of 20 randomized participants.
  • Three dropouts all occurred in MICT, leaving unequal completer groups.
  • HIIT was combined with resistance training, limiting attribution to interval training alone.
  • VO2max was estimated by walking test, not directly measured by maximal gas exchange.
  • Body fat percentage was estimated by girth equations, not imaging or DXA.
  • Participants were young healthy overweight adults, so findings may not generalize to older adults, obesity, or clinical populations.
  • No food restriction was imposed; dietary changes were self-reported rather than tightly controlled.

Safety

  • None of the recruited subjects reported any training-related injury.
  • The paper does not describe a detailed adverse-event monitoring protocol beyond injury reporting.