Polar s610i heart rate monitor

To main exercise for the endurance group consisted of 30 min (3 × 10-min with 120 s interval) of running with 65–70% of MHR (208–0.7 (age); approximately 100-to-110 beat/min). The MHR was assessed using Polar S610i heart rate monitor (FIN, 90440, FINLAND).

The cycling VO_2max test protocol utilized in this study and its results has been described elsewhere (Vikmoen et al. 2016a). Briefly, the test was initiated with 1‐min cycling at a power output of 100 W that was subsequently increased by 25 W every minute until exhaustion. VO₂ was measured (30‐sec sampling time) using a computerized metabolic system with mixing chamber (Oxycon Pro, Erich Jaeger, Hoechberg, Germany). The gas analyzers were calibrated with certified calibration gases of known concentrations before every test. The flow turbine (Triple V, Erich Jaeger, Hoechberg, Germany) was calibrated before every test with a 3 l, 5530 series, calibration syringe (Hans Rudolph, Kansas City, USA). VO_2max was calculated as the average of the two highest 30 sec VO₂ measurements. Peak cycling performance during the test (W_max) was calculated as the mean power output during the last 2 min of the incremental test. After the test, blood [la⁻] and HR_peak was noted. [La⁻] were analyzed in whole blood with a Lactate Pro LT‐1710 analyzer (Arcray Inc., Kyoto, Japan). RPE was recorded using the Borg scale (Borg, 1982). HR was measured using a Polar S610i heart rate monitor (Polar, Kempele, Finland).