Carbohydrate supplementation and psychophysiological responses during moderate exercise in hypoxia

Abstract

Background: Rating of Perceived Exertion (RPE) is a subjective scale to monitor overload and fatigue during exercise. Hypoxia may worsen the perception of fatigue, compromising the self-reported perception of effort and increasing RPE. The objective was to evaluate the effects of carbohydrate (CHO) supplementation on RPE during exercise in hypoxia simulating 4200 m. Methods: Eight male physically active volunteers performed two exercises at 50% VO 2peak and 1% slope: exercise in hypoxia + placebo or exercise in hypoxia + CHO (6% maltodextrin) with supplementation at 20, 40, and 60 min during exercise. Oxygen Saturation (SaO 2 %) was assessed at baseline and after exercise, while RPE and HR were measured each 10 min during the trial. Results: SaO 2 % decreased after exercise in both conditions of hypoxia compared to rest. The RPE did not differ between groups. However, the RPE increased in hypoxia after 20 min of exercise in relation to 10 min. The Area Under the Curve (AUC) of RPE was lower in hypoxia + CHO compared to hypoxia. The AUC of the HR/RPE ratio in the hypoxia + CHO group was higher in relation to hypoxia. Conclusions: Our results indicate that CHO supplementation does not change RPE induced by 60 min of exercise at 50% VO 2peak in hypoxia equivalent to 4200 m at the different times analyzed. However, in hypoxia + CHO the (AUC)-60 min of total RPE decreased during exercise, while the heart rate/RPE ratio improved, indicating lower RPE in the hypoxic environment.

Carbohydrate and Glutamine Supplementation Attenuates the Increase in Rating of Perceived Exertion during Intense Exercise in Hypoxia Similar to 4200 m

“…In normoxia, RPE is associated with glycemia and carbohydrate supplementation during long-term exercise [ 38 ]. During moderate exercise in hypoxia similar to 4200 m, carbohydrate supplementation can mitigate the increase in RPE [ 13 ]. However, this is the first study carried out to evaluate the effects of supplementation during intense exercise in hypoxia and suggest that the effects of supplementation on RPE may depend on blood glucose and not on the intensity of exercise or SaO 2 .…”

“…Every minute, speed was increased by 1.0 km/h until the volunteers were exhausted. Heart rate was measured every minute with a frequency meter, blood pressure was monitored using a sphygmomanometer and stethoscope, and the perception of effort was assessed using the RPE scale (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The equipment was calibrated according to the manufacturer's recommendations to measure ventilatory parameters…”

“…The increase in RPE seems to correlate with the reduction in SaO 2 and increase in heart rate at altitudes greater than 2543 m [ 12 ]. Psychobiological changes over 2500 m, including mood and congestion, may worsen the self-reported perception of effort [ 13 ].…”

“…A previous study showed that carbohydrate supplementation reduced RPE during moderate exercise (50% peak oxygen uptake) and RPE area under curve for 60 min in hypoxia equivalent to 4200 m, while the heart rate/RPE ratio increased, suggesting lower RPE [ 13 ]. However, the effects of intense exercise on RPE in hypoxia are not unquestionably known.…”