Effect of High-Intensity Interval Training Combined with Blood Flow Restriction at Different Phases on Abdominal Visceral Fat among Obese Adults: A Randomized Controlled Trial

Li S, Guo R, Yu T, Li S, Han T, Yu W

Question

Does adding blood flow restriction during the exercise or recovery phase of cycle HIIT improve abdominal visceral fat and metabolic outcomes more than HIIT alone in obese adults?

Summary

In obese adults, 12 weeks of supervised cycle HIIT reduced fat and metabolic markers compared with no training. Adding blood flow restriction improved some body-fat and glucose outcomes more than HIIT alone, and applying BFR during recovery intervals reduced abdominal visceral fat more than applying it during exercise. Because BFR uses cuffs, pressure calibration, and close safety monitoring, this is not directly suitable for ordinary app workout generation.

Methodology

Obese adults from Qingdao City, China, with body fat percentage over 30% and no regular aerobic training.
72 participants.
Cycle ergometer with bilateral thigh BFR cuffs.
Work intervals: 3 minutes sprint/cycling at 85% VO2max intensity.
Recovery: 3 minutes rest on ergometer with BFR applied in interval group.
Intensity: 85% VO2max; BFR at 40% limb occlusive pressure during rest intervals.
36 minutes including 10 minute warm-up.
2 sessions/week.
12 weeks; 24 sessions.
Randomized controlled trial
Whole-body and regional fat, Abdominal visceral and subcutaneous fat, Blood glucose and lipids, and Acute physiological load were tracked.

Outcomes

Whole-body and regional fat

All exercise groups reduced fat measures versus baseline and control; BFR groups improved trunk fat mass and fat percentage more than HIIT alone.

Exercise groups improved vs control p<0.05; I and E groups improved trunk fat mass and fat% more than H p<0.05; I improved android and whole-body fat mass more than H p<0.05.

Improved

Abdominal visceral fat

HIIT with BFR during recovery intervals produced the greatest abdominal visceral fat reduction.

I group AVFA reduction superior to H and E groups, p<0.05.

Improved

Blood glucose and insulin

All exercise groups improved blood glucose/lipid indices versus control; BFR groups improved glucose and insulin more than HIIT alone.

Exercise groups vs C p<0.05; E and I improvements in blood glucose and insulin better than H p<0.05.

Improved

Physiological load and tolerability

BFR increased growth hormone, epinephrine, and lactate responses, especially interval-phase BFR, but side effects were not reported.

E and I GH greater than H immediately and 30 min post p<0.05; I EPI greater than H post p<0.05; I lactate greater than E and E greater than H p<0.05.

Mixed

Insights

The core HIIT structure is clear: 10-minute warm-up, then 4 x 3 minutes hard / 3 minutes rest at 85% VO2max.
BFR is a specialist add-on requiring cuff pressure measurement, contraindication screening, and emergency planning, so it should not be generalized to consumer HIIT.
Applying extra metabolic stress during recovery intervals may amplify physiological load, but safety and implementation barriers are substantial.

Limitations

Hormone measures were not corrected for plasma volume.
GH and epinephrine sampling used limited timepoints, so peak timing could be missed.
Mechanisms of BFR for visceral fat reduction were not comprehensively explored.
Population and sex details were incompletely reported in the paper.

Safety

Side effects were not reported in any group during training or testing.
Authors noted high-intensity exercise could cause nausea, muscle cramps, or muscle soreness.
Exercise physiologists monitored safety; HR and RPE were monitored; emergency plans were prepared.
Participants could quit for physical or psychological discomfort or tiredness.