Abstract
There is no consensus in the literature that supports the inclusion of protein in the carbohydrate supplement in endurance exercise. The purpose of this study was to compare the physical performance of amateur runners under three different supplementation protocols: placebo (PLA), carbohydrate (CHO) and carbohydrate plus protein (CHO + PTN). Twelve amateur runners performed three exercise protocols on separate occasions consisting of 60 initial minutes with intensity referring to the Anaerobic Threshold (AT) and then 10% above the AT until exhaustion. Supplements (150 mL) were ingested 15 minutes before starting the activity and every 20 minutes until the first hour of exercise. Biochemical analyzes (blood glucose and lactate) and rating of perceived exertion (RPE) were measured before, during and after exercise protocols. Total caloric intake (Kcal) and macronutrients (g) were evaluated in the 24 hours preceding each exercise protocol. The time of exhaustion was higher for the CHO group when compared to the PLA group (24.6±13.6 vs. 15.2±8.9 minutes, p = 0.001) and the CHO + PTN group (24.6±13.6 vs. 18.6±8.4 minutes, p = 0.01). In general, glycemia was higher for the CHO and CHO + PTN groups when compared to the PLA group at all times whereas lactate, RPE and dietary assement did not show great differences. Our results suggest that, unlike supplementation with CHO alone, the addition of PTN in CHO supplements does not result in improved performance for the studied population and exercise intensity.
Highlights
The importance of carbohydrate (CHO) for skeletal muscle to remain active during exercise is something that has been studied for a long time [1]
It has been increasingly elucidated in the literature that the longer the duration of endurance exercise, greater is the ergogenic effect resulting from supplementation with CHOs [2]
Duration, and type of exercise may favor the benefit of adding PTN to the CHO supplement [16], since the studies cited that resulted in improved performance after PTN addition were performed with very long exercise duration (>3 hours) and milder intensity (80 to 85% VO2Max) when compared to those who did not find Journal of Food and Nutrition Research benefits
Summary
The importance of carbohydrate (CHO) for skeletal muscle to remain active during exercise is something that has been studied for a long time [1]. The addition of 1g of protein (PTN) to every 3 to 4g of CHO (1: 3-4 ratio) seems to increase athlete exhaustion time by virtue of attenuating central fatigue and improve the insulin response [6], thereby sparing endogenous carbohydrates [7] which resulted in a lower oxidation of CHO during exercise [8]. This aspect is not fully elucidated in the literature yet. Duration, and type of exercise may favor the benefit of adding PTN to the CHO supplement [16], since the studies cited that resulted in improved performance after PTN addition were performed with very long exercise duration (>3 hours) and milder intensity (80 to 85% VO2Max) when compared to those who did not find
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