Key Points
- Determine heart rate responses and the percentage of maximal heart rate at the anaerobic threshold to evaluate heart rate as a metric for activity prescription.
- Assessed 20 young women during incremental cycle ergometer exercise to exhaustion, increasing workload by 25 W each minute.
- Measured pulmonary ventilation and gas exchange every 30 seconds and recorded heart rate every minute, determining anaerobic threshold via non-linear breakpoints in ventilatory equivalents and gas exchange.
- Derived heart rate at the anaerobic threshold by regressing individual heart rate values against oxygen consumption.
- Participants reached a mean VO2max of 38.4 ± 4.7 ml·min⁻¹·kg⁻¹ with a maximal heart rate of 183.0 ± 8.0 bpm; anaerobic threshold occurred at 27.0 ml·min⁻¹·kg⁻¹ (70.1% VO2max) and 158.4 ± 12.4 bpm (86.3% HRmax).
- Exercising within the 75–90% HRmax range (58–75% VO2max) produced non-uniform metabolic stress, resulting in anywhere from 1 to 14 participants exercising above their anaerobic threshold.
- A moderate correlation of r = 0.60 was observed between percentage of maximal heart rate and percentage of VO2max at the anaerobic threshold.
Structured PICO
IInterventionIncremental (25 W each min) cycle exercise to exhaustion
OOutcomeHeart rate response and percent maximal HR (%HRmax) at the anaerobic threshold (AT)surrogate
Heart rate can be used to regulate activity above or below the anaerobic threshold, but requires individual assessment due to variability in the correlation between %HRmax and %VO2max at the threshold.