Combined carbohydrate–protein supplementation improves competitive endurance exercise performance in the heat

Abstract

Laboratory-based studies have demonstrated that adding protein (PRO) to a carbohydrate (CHO) supplement can improve thermoregulatory capacity, exercise performance and recovery. However, no study has investigated these effects in a competitive sporting context. This study assessed the effects of combined CHO-PRO supplementation on physiological responses and exercise performance during 8 days of strenuous competition in a hot environment. Twenty-eight cyclists participating in the TransAlp mountain bike race were randomly assigned to fitness-matched placebo (PLA 76 g L(-1) CHO) or CHO-PRO (18 g L(-1) PRO, 72 g L(-1) CHO) groups. Participants were given enough supplements to allow ad libitum consumption. Physiological and anthropometric variables were recorded pre- and post-exercise. Body mass decreased significantly from race stage 1 to 8 in the PLA group (-0.75 ± 0.22 kg, P = 0.01) but did not change in the CHO-PRO group (0.42 ± 0.42 kg, P = 0.35). Creatine kinase concentration and muscle soreness were substantially elevated during the race, but were not different between groups (P = 0.82, P = 0.44, respectively). Urine osmolality was significantly higher in the CHO-PRO versus the PLA group (P = 0.04) and the rise in tympanic temperature from pre- to post-exercise was significantly less in CHO-PRO versus PLA (P = 0.01). The CHO-PRO group also completed the 8 stages significantly quicker than the PLA group (2,277 ± 127 vs. 2,592 ± 68 min, respectively, P = 0.02). CHO-PRO supplementation therefore appears to prevent body mass loss, enhance thermoregulatory capacity and improve competitive exercise performance despite no effect on muscle damage.

Addition of Protein in Carbohydrate Supplementation Does not Improve Performance of Amateur Runners in Exercise above the Anaerobic Threshold

“…Study with trained cyclists verified that those who received CHO+PTN supplementation in an interval activity characterized by 45 to 75% of the Maximum Oxygen Consumption (VO2Max) with 3 hours of duration obtained a longer time to exhaustion (TTE) in a subsequent activity to 85% VO2Max when compared to groups that received only CHO or placebo (PLA) [9]. In line of this, other studies also found an improvement in performance after the addition of PTN in the CHO supplement [10,11,12]. On the other hand, other authors [13,14,15] did not observe improvement in the performance of individuals who received CHO+PTN supplementation.…”

“…Some authors proposed an initial exercise protocol with a much longer time (≥ 120 minutes) and an intensity for the athletes to reach exhaustion at the end of exercise much lower (80 to 85% VO2Max) [9,11,12] when compared to the present study (60 minutes and 90% VO2Max, respectively). Another study [10] that also showed a positive effect on protein addition used this intervention in a chronic way (for 8 days) with ad libitum intake of the supplement making it difficult to compare with our research. Possible explanations for this fact are that prolonged exercises require a greater contribution of PTN as an energy source [32] whereas activities with intensities above AT use predominantly CHO to produce ATP through the oxidation of glucose by glycolytic pathway [33].…”

Changes in hydration status of elite Olympic class sailors in different climates and the effects of different fluid replacement beverages

“…Saunders et al [42] found the use of a fluid replacement drink fortified with protein during a two cycle-to-exhaustion tests within the same day was effective in attenuating the nutritional deficit incurred during exercise and helped to reduce skeletal muscle damage compared to a carbohydrate electrolyte drink alone. Therefore, performing multiple bouts of exercise within a day or consecutive days of competition may be necessary to fully observe the nutritional and physiologic effects of protein ingested with a carbohydrate electrolyte beverage during exercise [43]. …”

Optimal Nutrition for Endurance Exercise: A Systematic Review

“…RER was consistently higher in the CHO-PRO condition than the other conditions and mean heart rate was consistently lower in CHO condition compared to the others. Conversely, Cathcart et al did observe differences in endurance performance after randomizing 28 competitive mountain bikers to either CHOonly (control) supplements or CHO-PRO supplements [27]. Overall, those consuming the CHO-PRO supplement performed significantly faster than the placebo.…”