PMID 31395812

Research
All papers

Blood Lactate Concentration Is Not Related to the Increase in Cardiorespiratory Fitness Induced by High Intensity Interval Training

Astorino TA, DeRevere JL, Anderson T, Kellogg E, Holstrom P, Ring S, Ghaseb N

Question

Are blood lactate response, sleep duration, energy intake, or training heart rate associated with VO2max improvement after a brief HIIT program?

Summary

In 14 already active adults, 3 weeks of cycling HIIT improved VO2max by about 6%. Blood lactate response, energy intake, and sleep duration did not predict the VO2max change, but higher training heart rate was associated with larger improvements.

Methodology

  • Recreationally active adults recruited by convenience sampling
  • 14 participants.
  • Electrically braked cycle ergometer.
  • Work intervals: 1 min at 130% ventilatory threshold.
  • Recovery: 75 s active recovery at 10% peak power output.
  • Intensity: 130% ventilatory threshold, equal to about 70% peak power output; elicited about 90% +/- 5% PPO and 95% +/- 3% HRmax.
  • 5 min warm-up plus intervals and recoveries.
  • 3 sessions/week.
  • 3 weeks.
  • Single-group pre-post training study
  • VO2max, Blood lactate, Sleep, and Energy intake were tracked.

Outcomes

VO2max

VO2max increased after nine HIIT sessions.

p = 0.007; +6%; +0.15 +/- 0.13 L/min and +2.4 +/- 1.8 mL/kg/min

Improved

Blood lactate

Blood lactate response did not predict VO2max improvement.

Delta VO2max vs BLa r = 0.44, p = 0.10; mean BLa day 1 r = 0.17, p = 0.57; day 9 r = 0.48, p = 0.08

No clear change

Sleep

Sleep duration was not associated with VO2max change.

r = 0.14, p = 0.62

No clear change

Energy intake

Energy intake was not associated with VO2max change.

r = 0.38, p = 0.18; intake 2050 +/- 686 to 2074 +/- 639 kcal, p = 0.39

No clear change

Heart rate

Higher training heart rate was associated with larger VO2max improvement.

r = 0.62, p = 0.02; mean training HR 95% +/- 3% HRmax

Improved

Insights

  • A brief 3-week HIIT block can improve VO2max even in already active adults.
  • Heart-rate response may be a more useful training signal than lactate for predicting VO2max response in this protocol.
  • The study is not evidence that lactate is irrelevant in all HIIT programs; it used threshold-based cycling in a small sample.

Limitations

  • No control group
  • Small sample
  • Active participants rather than sedentary users
  • Self-reported diet and sleep
  • Brief training duration
  • Underpowered for sex-specific effects

Safety

  • No adverse-event reporting was identified in the the paper; participants were apparently healthy and exercised in the lab.