PMID 33098020

Research
All papers

The acute physiological and perceptual effects of recovery interval intensity during cycling-based high-intensity interval training

Fennell CRJ, Hopker JG

Question

How does recovery interval intensity affect physiological and perceptual responses during self-paced cycling-based aerobic HIIT?

Summary

Fourteen trained cyclists completed six randomized lab HIIT sessions: 6 x 4 minutes or 3 x 8 minutes, each with passive recovery, active recovery at 80% lactate-threshold power, or active recovery at 110% lactate-threshold power. Passive recovery let cyclists produce higher work-interval power and spend more time at high percentages of maximal minute power while producing similar oxygen-uptake stress and lower session RPE than the hardest active recovery.

Methodology

  • Fourteen trained cyclists with at least 2 years competitive racing experience.
  • 14 participants.
  • Cycling.
  • Work intervals: 6 x 4 min or 3 x 8 min self-paced maximal session effort.
  • Recovery: Passive seated recovery, active recovery at 80% LT power, or active recovery at 110% LT power.
  • Intensity: Highest possible work-interval power output; recovery at PA, 80A, or 110A.
  • About 52-54 min including warm-up, between-interval recoveries, and cooldown.
  • Six lab sessions on non-concurrent days.
  • Acute crossover study.
  • Randomized repeated-measures crossover laboratory study.
  • Power output, Oxygen uptake, Session RPE, and Muscle oxygenation were tracked.

Outcomes

Work power

Passive recovery increased time above high percentages of MMP and supported higher work-interval power than active recovery.

Time above 80%, 90%, and 95% MMP higher with PA than 80A and 110A during both protocols; all p<=0.001.

Improved

VO2 stress

Recovery intensity did not significantly change time above 90% or 95% VO2peak during work intervals.

>90% VO2peak p=0.11; >95% VO2peak p=0.50.

No clear change

Session RPE

110A active recovery made sessions feel harder than passive or 80A recovery.

6 x 4 sRPE: PA 8.3 +/- 0.7, 80A 8.7 +/- 0.6, 110A 9.1 +/- 0.5; 3 x 8 sRPE: PA 8.6 +/- 0.7, 80A 8.5 +/- 0.6, 110A 9.1 +/- 0.5; p<=0.001.

Safety concern

Blood lactate

Active recovery showed lower lactate in the 6 x 4 session, likely because work-interval intensity was lower.

BLa recovery-intensity main effect for 6 x 4 p<0.001; not significant for 3 x 8 p=0.06.

Mixed

Insights

  • Passive recovery can be a better default between hard long cycling intervals when work quality matters.
  • Active recovery above lactate threshold can make a session harder without improving VO2 time at target.
  • Recovery intensity should be prescribed and tracked as part of HIIT design.

Limitations

  • Small trained-cyclist sample.
  • Acute crossover design only.
  • No chronic adaptation outcomes.
  • Cycling lab setting limits transfer to bodyweight HIIT.
  • Sex distribution was not stated in the extracted NXML.

Safety

  • No adverse events were reported.
  • Participants were trained cyclists tested under laboratory monitoring.