PMID 24782684

Research
All papers

High-intensity interval training and beta-hydroxy-beta-methylbutyric free acid improves aerobic power and metabolic thresholds

Robinson EH 4th, Stout JR, Miramonti AA, Fukuda DH, Wang R, Townsend JR, Mangine GT, Fragala MS, Hoffman JR

Question

Does HMB free acid supplementation enhance aerobic fitness and metabolic-threshold adaptations to four weeks of cycle-ergometer HIIT in healthy college-aged men and women?

Summary

In healthy college-aged adults, four weeks of cycling HIIT improved some endurance measures, and adding HMB free acid produced larger gains in VO2peak and ventilatory threshold than HIIT with placebo. Body composition did not significantly change, and the study is partly supplement evidence rather than workout-only evidence.

Methodology

  • Healthy recreationally active college-aged men and women
  • 34 participants.
  • Cycle ergometer.
  • Work intervals: 2 minutes.
  • Recovery: 1 minute complete rest.
  • Intensity: 80-120% maximal workload.
  • About 19-23 minutes including warm-up.
  • 3 sessions/week.
  • 4 weeks.
  • Double-blind placebo-controlled training study with non-training control
  • VO2peak, Ventilatory threshold, Time to exhaustion, and Body composition were tracked.

Outcomes

VO2peak

HMBFA-HIIT had greater VO2peak gains than control and placebo-HIIT.

ANCOVA p=0.003 overall; HMBFA-HIIT vs CTL p=0.001, vs PLA-HIIT p=0.032

Improved

thresholds

HMBFA-HIIT improved ventilatory threshold; both HIIT groups improved RCP compared with control.

Reported p<0.05

Improved

time to exhaustion

Both HIIT groups improved time to exhaustion versus control without significant difference between HIIT groups.

Reported p<0.05 versus CTL

Improved

body composition

No significant differences were observed for body composition.

No clear change

Insights

  • Two-minute cycling intervals with short rest can build aerobic threshold and performance.
  • Use supplement-linked claims only as background, not core HIIT generation evidence.
  • No body-composition change after 4 weeks despite performance gains.

Limitations

  • Small groups
  • Supplement co-intervention
  • Short 4-week duration
  • No detailed adverse-event reporting
  • Healthy college sample

Safety

  • The article did not report intervention-related adverse events, injuries, or symptoms.
  • Before final analysis, 3 female and 2 male participants were removed for health reasons not associated with the study, and 1 female participant was removed after a family emergency.
  • Participants self-reported no musculoskeletal injury on PAR-Q, gave informed consent after risks and benefits were explained, and supplement logs/returned packets showed 99% compliance.