Influence of sex and training status on cardiac and baroreceptor function following combined high‐intensity interval exercise and orthostatic stress

Abstract

Training status and sex have been shown to impact sympathetic activation with intense exercise, and tolerance to orthostatic challenges. The purpose of this investigation was to assess the effects of sex and training status on cardiac and autonomic responses following high‐intensity interval exercise (HIT) and lower body negative pressure (LBNP). We hypothesized that endurance‐trained (ET) females would display greatest decrements. Ventricular function (echocardiography) and baroreceptor sensitivity (BRS) were assessed in 33(13f) normally active (NA) and ET subjects during LBNP (0, −20, −40 and −60 mmHg), before and after HIT (15 bouts of 1:2 min work:recovery cycling at 100 and 40%, respectively). A three‐way mixed model ANOVA was used to compare dependent variables between sex and training status, within LBNP and condition. Men and women responded similarly to combined HIT and LBNP. Throughout, women displayed enhanced strain, diastolic strain rate, and BRS (P>;0.05). Pre‐exercise BRS decreased greater in ET than NA (0 to −60 mmHg: NA, 17.3±12.8 to 17.0±17.5; ET, 26.1±10.5 to 16.9±4.1, ms/mmHg), but post‐exercise, recovery of BRS was more rapid in ET (NA, 9.6±5.0 to 9.4±5.5; ET, 8.2±4.4 to 13.5±7.6, ms/mmHg; P<0.01). In conclusion, it would appear that the cardiac and autonomic stability of ET and women during an orthostatic challenge is not compromised in the face of short (45 min) high‐intensity training.