The effects of four weeks of creatine supplementation and high-intensity interval training on cardiorespiratory fitness: a randomized controlled trial
Question
Does creatine supplementation add to cardiorespiratory or performance adaptations from a 4-week cycling HIIT program?
Summary
Recreationally active college-aged men improved VO2peak, time to exhaustion at VO2peak, and ventilatory threshold after 4 weeks of cycling HIIT. Creatine did not further improve VO2peak and did not improve a separate total-work-done test, though it may have contributed to ventilatory-threshold changes.
Methodology
- Recreationally active college-aged men
- 43 participants.
- Cycle ergometer.
- Work intervals: Five 2-minute exercise bouts.
- Recovery: 1-minute passive rest between bouts.
- Intensity: Difficult days progressed from 90% to 120% of baseline VO2peak maximum workload; recovery days at 80%.
- 5-minute warm-up plus interval set; cool-down not reported.
- 5 days per week.
- 4 weeks main training/treatment.
- Randomized controlled trial with double-blind creatine/placebo supplementation and a non-training control group
- VO2peak, VO2peak time to exhaustion, Ventilatory threshold, and Total work done were tracked.
Outcomes
VO2peak
Both HIIT groups increased VO2peak, with no additional creatine benefit.
Time x treatment P < 0.001; creatine 3.60 +/- 0.55 to 3.87 +/- 0.47 L/min, P = 0.002; placebo 3.65 +/- 0.59 to 4.00 +/- 0.59, P = 0.001
VO2peak TTE
Both training groups increased time to exhaustion during the VO2peak test.
Creatine 818.3 +/- 127.2 to 869.3 +/- 130.0 s; placebo 837.7 +/- 130.1 to 899.4 +/- 127.9 s; P < 0.001 for each
VT
Ventilatory threshold improved clearly in the creatine group; placebo change did not meet the Bonferroni-adjusted threshold.
Interaction P = 0.040; creatine 2.14 +/- 0.53 to 2.49 +/- 0.57, P = 0.001; placebo P = 0.040 with Bonferroni threshold P < 0.017
TWD
Total work done at 110% maximum workload did not improve.
No significant change reported
Insights
- Cycling HIIT with five 2-minute bouts can improve cardiorespiratory fitness in recreationally active men within 4 weeks.
- Creatine should not be presented as improving VO2peak adaptations to HIIT based on this trial.
- The protocol mixed hard interval days with lower-intensity recovery days across the training week.
Limitations
- Short intervention.
- Male-only college-aged sample.
- Supplement dose did not use a creatine loading phase, which the authors discuss as a possible reason for limited effects.
- Adherence and adverse events were not numerically reported in detail.
Safety
- No adverse events, injuries, or supplement side effects were reported in the article. Safety/context details reported: participants were screened for heart and joint conditions and recent supplement/creatine use, supplementation was supervised to monitor compliance, and cycle HIIT was conducted in the laboratory; exercise attendance, dropout, and tolerability were not numerically reported.