Carbohydrate-protein (CHO-PRO) and carbohydrate (CHO) beverages are two popular nutritional supplements currently used by many athletes to improve exercise performance. Research regarding these supplements effectiveness during resistance exercise (RE) has been inconsistent. PURPOSE: The purpose of this investigation was to determine the effect of CHO-PRO versus CHO supplementation and a placebo (PLA) on RE performance, perceived exertion during RE, and post-exercise salivary cortisol. METHODS: Twenty seven college aged (18 to 30 yrs) healthy males who participated in recreational strength training were recruited from the university community to participate in this investigation. Subjects randomly received either a: 1) CHO-PRO; 2) CHO; or 3) PLA supplement 15 minutes prior to exercise, between every other set during exercise, and immediately post-exercise. Subjects completed a RE session consisting of multiple sets of seated leg press exercise starting with 1 set of 10 repetitions at 40, 50, and 60% of 1 repetition maximum (RM), continuing with multiple sets of 8 to 10 repetitions at 70% of their 1 RM until fatigue. Ratings of perceived exertion for the active muscle group (RPE-AM) and overall body (RPE-O) were measured immediately following each set and Session-RPE was measured 30 minutes after the RE session concluded. Salivary cortisol samples were collected approximately 15 minutes prior to v exercise and 30 minutes post-exercise. RESULTS: CHO-PRO and CHO supplementation resulted in a significantly greater total number of repetitions performed to fatigue than a PLA. CHO supplementation resulted in an attenuated RPE-AM response at 25% and 50% of total volume of work performed compared to the CHO-PRO supplementation or a PLA. There were no significant differences for RPE-O or Session-RPE between the three treatment groups. Finally, CHO supplementation resulted in an attenuation of post-exercise salivary cortisol response compared to CHO-PRO supplementation or a PLA. CONCLUSION: The results of this investigation suggest that both CHO-PRO and CHO supplementation before and during RE can have a positive impact on exercise performance which may ultimately lead to enhanced muscular adaptations and improved sport performance.

The purpose of this study was to compare energy expenditure (EE) of single-set and multiple-set resistance exercise protocols using indirect calorimetry. Twelve men and twelve women (age = 21.4 ± 1.3 years) performed a single-set (SS) and multiple-set (MS) resistance exercise protocol in random order. The subjects performed two protocols at 70% of their 1-repetition maximum. The protocols consisted of 5 upper-body exercises of either 1 or 3 sets per exercise performed in random order. Metabolic and cardiorespiratory data were recorded over the entire exercise session and during 5 minutes of recovery by a portable metabolic measurement system. Gross (167.9 ± 58.7 kcal) and net (88.3 ± 41.6 kcal) EE for the MS protocol were significantly greater (p < 0.001) than gross (71.3 ± 26.5 kcal) and net (36.3 ± 18.7 kcal) EE of the SS protocol. Conversely, there was no significant difference in the rate of EE between both protocols. Significant gender differences (p < 0.001) in absolute and relative EE were observed for both protocols where values in men were higher than women. Heart rate, respiratory rate, relative V[Combining Dot Above]O2, respiratory exchange ratio, and minute ventilation values were significantly higher during the MS than the SS protocol. The results of this study indicated that MS protocols yield greater metabolic and cardiovascular demands than SS protocols when the number of exercises performed is the same.

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