Ml 6500

Participants performed a graded exercise test to exhaustion on a treadmill (MAT-2700, Fukuda Denshi, Japan) to determine the ${\displaystyle \stackrel{·}{\mathrm{V}}}$ O₂peak. The graded exercise test was started at 1 km/h and 0% slope, and the speed and slope of the treadmill were increased every minute by approximately 1 metabolic equivalent until the participants were exhausted [16 (link),17 (link)]. During the exercise, a 12-lead electrocardiogram was electronically recorded (Stress Test System ML-6500, Fukuda Denshi, Japan), and the heart rates were derived from the RR interval. Pulmonary gas exchange parameters (oxygen uptake ( ${\displaystyle \stackrel{·}{\mathrm{V}}}$ O₂), carbon dioxide output ( ${\displaystyle \stackrel{·}{\mathrm{V}}}$ CO₂), and respiratory exchange ratio (RER)) were determined in a breath-by-breath assessment using a gas analyser (AE-300S, Minato Medical Science, Osaka, Japan). Maximal metabolic measurements and heart rate were recorded only if the participants met at least two of the following three criteria [18 (link)]: (1) achieved ${\displaystyle \stackrel{·}{\mathrm{V}}}$ O₂ plateau (<150 mL/min) despite increasing the exercise intensity; (2) the highest heart rate measured during the last minute of the exercise was >90% of the predicted maximal heart rate (220 − age (in years)); and (3) the highest RER during the final stage of the incremental exercise was >1.10.