Hydration status, sweating rate, heart rate and perceived exertion after running sessions in different relative humidity conditions: a randomized controlled trial

ABSTRACT The purpose of this study was to analyze the impact of running in normal relative humidity (RH = 53%) and very high RH (94%) on hydration status (HS), sweating rate (SR), heart rate (HR), and rating of perceived exertion (RPE). Fourteen men (25.2 ± 6.6 yrs) performed two sessions of treadmill running. Body mass (normal RH: -1.35%, very high RH: -1.65%) HS (normal RH: -14.8%; very high RH: -20.8%) were reduced while RPE (normal RH: +26%; very high RH: +28%) and HR were increased (very high RH: +5.8%: 20-40 min, +3.1%: 40-60 min, +3%: 20-40 min; +2.3%: 40-60 min for normal RH). As expected, SR was significantly greater during very high RH (-20/8%) compared to normal RH (-14.8%). Running in very high RH at moderate temperature has a greater negative impact on SR, HS, body mass, HR, RPE in men than running in normal RH at the same temperature, which places the runner in greater danger of heat illnesses such as heat exhaustion or heat stroke.

RESUMO Analisar o impacto da corrida em diferentes humidade relativa (HR) (normal (53%), muito alto (94%)), estado de hidratação (EH), taxa de transpiração (TT), freqüência cardíaca (FC), esforço percebido (RPE). Quatorze homens (25,2 anos) realizaram duas sessões de corrida em esteira. Massa corporal (HR normal: -1,35%, HR muito alta: -1,65%) e EH reduziram (HR normal: -14,8%, HR muito alta: -20,8%), RPE (HR normal: + 26%, HR muito alta: + 28%), aumento da FC (HR muito alta: + 5.8%: 20-40 min, + 3.1%: 40-60 min, HR normal: + 3%: 20-40 min; + 2.3%: 40-60 min). TT foi significantemente diferente entre HR (HR normal: -14.8%, HR muito alta: -20.8%). Há um impacto negativo na corrida em EH, massa corporal, FC e RPE em homens com HR normal e muito alta, e TT é mais afetada com HR muito alta.

RESUMEN El objetivo de este estudio fue analizar las repercusiones de correr con diferentes niveles de humedad relativa (HR) (normal [53%], muy alta [94%]) sobre el estado de hidratación (EH), la tasa de sudoración (TS), la frecuencia cardíaca (FC) y el esfuerzo percibido (EP). Catorce hombres (25,2 ± 6,6 años) realizaron dos sesiones en cinta de correr. La masa corporal (HR normal: -1,35%; HR muy alta: -1,65%) y el EH (HR normal: -14,8%; HR muy alta: -20,8%) se redujeron, mientras que el EP (HR normal: +26%; HR muy alta: +28%) y la FC (HR muy alta: +5,8%: 20-40 min; +3,1%: 40-60 min; HR normal: + 3%: 20-40 min; + 2,3%: 40-60) aumentaron. La TS fue considerablemente diferente entre las HR (HR normal: -14,8%; muy alta HR: -20,8%). Hay repercusiones negativas por correr con una HR muy alta y una temperatura moderada en TS, EH, masa corporal, FC y EP en corredores que corren a una HR normal a la misma temperatura, lo que sitúa a estos en gran peligro de sufrir un enfermedad provocada por el calor, como agotamiento por calor o golpe de calor.

Twenty minutes of post-exercise hypotension are enough to predict chronic blood pressure reduction induced by resistance training in older women

AIM: This study investigated the correlation between post-exercise hypotension (PEH) and chronic blood pressure (BP) reduction in older women after a resistance training (RT) program. METHODS: Twenty-five older women (≥60 years) performed a RT program for 8 weeks, 3x/week consisting of 3 sets of 8-12 repetitions maximum in 8 exercises. Acute and chronic BP measurements were performed using automatic equipment, in which acute BP was measured before and after 10, 20, 30, 40, 50 and 60 min following the sixth exercise session, while chronic BP was measured pre and post-training. RESULTS: Significant decrease for systolic blood pressure (SBP) was observed after the intervention period, however, the diastolic blood pressure (DBP) did not change. To acute changes in BP, SBP decreased at all times after a single RT session, while DBP increased after 40 min. The reduction for SBP after a single RT session at baseline showed positive and significant correlations with the reductions in basal SBP observed after the 8 weeks of RT, the strongest correlations were observed at 20 min. A linear relationship between the magnitude of change in chronic SBP and the 20 min for acute SBP, and 30 min for acute DBP of post-exercise was observed. CONCLUSION: The results suggest that acute BP lowering after RT session is a reliable predictor of chronic BP response to exercise training, and 20 min of resting, after RT training, is enough to indicate chronic response of BP as this measure was highly associated with chronic BP lowering in older women.(AU)