H10 hr sensor

The Polar H10 HR sensor, validated against the ECG gold standard [51 (link)], was positioned at the xiphoid process of the sternum using an adjustable chest strap and a Polar M400 monitoring wristband. The recorded R-R interval data was then transferred to the computer using the Polar FlowSync (version 2.5) for analysis. Before processing, the inter-beat intervals (IBIs) were manually corrected for ectopic or missed beats [52 (link)]. Kubios HRV software version 3.5 (Biosignal Analysis and Medical Imaging Group, Kuopio, Finland) was used to analyze the parameters. An Autoregressive (AR) algorithm was used for power spectral analysis of the frequency series.

Submaximal exercise (RUN 1) began 90 min post-treatment. Participants ran for 60 min at a fixed speed (10 km·h⁻¹) and individualised gradient designed to elicit an intensity of 70% V̇O_2max. Respiratory gases were sampled continuously between 24–32 (24_EX), 37–45 (37_EX) and 50–58 (50_EX) min of exercise. Measures were collected at precisely the same time to minimise any influence of metabolic drift [28 (link)]. HR (Polar H10 HR Sensor), ratings of perceived exertion (RPE) on the Borg scale (6–20) [29 ], ratings of affect (i.e. pleasure–displeasure) on the Feelings Scale (–5 =“feeling very bad” to + 5 =“feeling very good”) [30 ], and finger prick blood lactate (BL) and glucose (BG) concentrations (in singlicate) (Edge® Blood Lactate Monitoring System; Accu-Check® Performa Meter) were also measured at 20 (20_EX), 40 (40_EX) and 60 (60_EX) minutes.