Protein intake above the Recommended Dietary Allowance (RDA) and resistance training are known anabolic stimuli to support healthy aging. Specifically, protein supplementation after resistance exercise and nightly are strategies to maximize utilization of protein intake above the RDA in healthy adults. As such, the primary objective was to examine the efficacy of protein supplementation and nutritional counseling resulting in either moderate (MOD: ~1.0 g·kg−1·d−1) or higher (HIGH: ~1.6 g·kg−1·d−1) protein intake during resistance training on strength (one-repetition maximum, 1-RM; isokinetic and isometric peak torque) in healthy middle-aged adults. Exploratory analyses include diet-exercise effects on lean body mass (LBM), clinical biomarkers, gut microbiota, and diet composition. 50 middle-aged adults (age: 50 ± 8 y, BMI: 27.2 ± 4.1 kg·m-2) were randomized to either MOD or HIGH protein intake during a 10-week resistance training program (3 × week). Participants received dietary counseling and consumed either 15 g (MOD) or 30 g (HIGH) of protein from lean beef in the immediate post-exercise period and each evening. Maximal strength (1-RM) for all upper and lower body exercises significantly increased with no effect of protein intake (P<0.050). There was a main effect of time for LBM (P<0.005). Cardiovascular, renal, or glycemic biomarkers were not affected by the intervention. Gut microbiota were associated with several health outcomes (P<0.050). In conclusion, higher protein intake above moderate amounts does not potentiate resistance training adaptations in previously untrained middle-aged adults. This trial was registered at clinicaltrials.gov as NCT03029975.

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance but also be readily digested and absorbed. Potatoes are a whole-food-based option that fulfills these criteria, yet their impact on performance remains unexamined. We investigated the effects of potato purée ingestion during prolonged cycling on subsequent performance vs. commercial CHO gel or a water-only condition. Twelve cyclists (70.7 ± 7.7 kg, 173 ± 8 cm, 31 ± 9 yr, 22 ± 5.1% body fat; means ± SD) with average peak oxygen consumption (V̇o2peak) of 60.7 ± 9.0 mL·kg−1·min−1 performed a 2-h cycling challenge (60–85% V̇o2peak) followed by a time trial (TT; 6 kJ/kg body mass) while consuming potato, gel, or water in a randomized-crossover design. The race fuels were administered with [U-13C6]glucose for an indirect estimate of gastric emptying rate. Blood samples were collected throughout the trials. Blood glucose concentrations were higher ( P < 0.001) in potato and gel conditions compared with water condition. Blood lactate concentrations were higher ( P = 0.001) after the TT completion in both CHO conditions compared with water condition. TT performance was improved ( P = 0.032) in both potato (33.0 ± 4.5 min) and gel (33.0 ± 4.2 min) conditions compared with water condition (39.5 ± 7.9 min). Moreover, no difference was observed in TT performance between CHO conditions ( P = 1.00). In conclusion, potato and gel ingestion equally sustained blood glucose concentrations and TT performance. Our results support the effective use of potatoes to support race performance for trained cyclists. NEW & NOTEWORTHY The ingestion of concentrated carbohydrate gels during prolonged exercise has been shown to promote carbohydrate availability and improve exercise performance. Our study aim was to expand and diversify race fueling menus for athletes by providing an evidence-based whole-food alternative to the routine ingestion of gels during training and competition. Our work shows that russet potato ingestion during prolonged cycling is as effective as carbohydrate gels to support exercise performance in trained athletes.

Resistance training combined with adequate protein intake supports skeletal muscle strength and hypertrophy. These adaptations are supported by the action of muscle stem cells (MuSCs) which are regulated, in part, by fibro-adipogenic progenitors (FAPs) and circulating factors delivered through capillaries. It is unclear if middle-aged males and females have similar adaptations to resistance training at the cellular level. To address this gap, 27 (13 males, 14 females) middle-aged (40-64 years) adults participated in 10-weeks of whole-body resistance training with dietary counselling. Muscle biopsies were collected from the vastus lateralis pre- and post-training. Type II fibre cross-sectional area increased similarly with training in both sexes (P = 0.014). MuSC content was not altered with training; however, training increased PDGFRα+/CD90+ FAP content (P < 0.0001) and reduced PDGFRα+/CD90- FAP content (P = 0.044), independent of sex. The number of CD31+ capillaries per fibre also increased similarly in both sexes (p<0.05). These results suggest that muscle fibre hypertrophy, stem/progenitor cell, and capillary adaptations are similar between middle-aged males and females in response to whole-body resistance training.

Objectives Yes-Associated Protein (YAP) is implicated as a regulator of the post-exercise skeletal muscle response through mechanical transduction. We recently observed that resistance exercise (RE) increased both total (t) and phosphorylated (p) muscle YAP content, which correlated with extracellular signal-regulated kinase 1/2 (Erk1/2). Other anabolic signaling pathways (i.e., mTORC1) are known to be potentiated by the combined stimuli of RE and protein ingestion during post-exercise recovery. However, the impact of protein ingestion on t- and p-muscle YAP content during recovery from RE is unknown. Therefore, we aimed to determine the nutrient sensitivity of YAP in both an acute and chronic exercise setting in aging skeletal muscle. Methods Acute study: 13 untrained older women (59.8 ± 0.5 y) were randomized to perform an acute bout of unilateral RE (3 sets × 12 repetitions at 65% of one repetition maximum) followed by the ingestion of whey protein (0.3 g/kg lean body mass) or water. Muscle biopsies of both the rested and exercised legs were collected before and during the postprandial period. Chronic study: 20 untrained middle-aged men and women (47.5 ± 0.3 y) performed 3 weeks of whole body RE (3 d/wk) with moderate or high protein intake set at 1.2 g/kg/d or 1.6 g/kg/d, respectively. Muscle biopsies were taken weekly in the rested state. Total and phosphorylated YAPSer127 and Erk1/2Thr202/Tyr204 were examined by western blotting. Results Acute study: Protein ingestion decreased t- and p-YAP compared to the water condition in the non-exercised leg (main effect: P &lt; 0.04). There was no change in t- or p-YAP, regardless of condition, in the exercised-leg throughout recovery (P = 0.88). There was no change in p/t ratio of Erk1/2 in the exercised or non-exercised leg.  Chronic study: There was no change in either p- or t-YAP in moderate and high protein conditions throughout training (both, P &gt; 0.05). There was a decrease in t-Erk1/2 irrespective of condition (P = 0.04). There was no change in p/t ratio of Erk1/2 throughout training. There was a significant correlation between t-Erk1/2 and t-YAP (r = 0.741 and P &lt; 0.001). Conclusions Protein ingestion mediated an acute down-regulation of YAP in the postprandial-state. However, resistance training did not modulate YAP content in aged skeletal muscle tissue. Funding Sources Funded by Beef Checkoff. AFS is supported by CAPES-Brazil.

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Objectives High protein diets (>1.6 g/kg/d) are thought to maximize daily myofibrillar protein synthesis (MPS) rates to resistance exercise training. Current research has focused on isolated protein sources to stimulate MPS disregarding other nutritional factors within a healthy diet. Therefore, we examined the impact of dietary counseling underlining food-focused healthy eating patterns equally distributing protein through high-quality sources at the Recommended Daily Allowance (RDA) or in excess on resistance exercise mediated daily rates of MPS in middle-aged adults. Methods Nineteen healthy middle-aged adults (11 M, 8F, 48 ± 7 y, BMI: 28.9 ± 3.7 kg/m2, 7451 ± 4957 steps/d) were randomized to consume protein at the RDA (0.8–1.0 g/kg/d, n = 10) or twice the RDA (2 × RDA, 1.6–1.8 g/kg/d, n = 9) for 2 weeks. Participants were counseled to equally distribute protein between meals and consumed either 15 g (RDA) or 30 g (2 × RDA) protein from lean beef in immediately post-exercise and nightly. Week 0 (−7 to 0 d) served as a dietary habituation, and week 1 (1–8 d) included whole body resistance exercise sessions (3/wk) with the dietary intervention. On 0 d, participants ingested 5 mL/kg over 10.5 h of deuterated water (2H2O) for deuterium enrichment of body water, with maintenance daily doses of 0.625 mL/kg/d 2H2O for days 1–8. Repeated saliva and muscle biopsies from the vastus lateralis were collected throughout the 1-week intervention to assess daily rates of MPS. Results The 2 × RDA group (1.6 ± 0.4 g/kg/d) consumed significantly more protein than the RDA group (1.0 ± 0.4 g/kg/d, P = 0.01). Steady-state body water enrichment was not different (P = 0.94) between the 2 × RDA (0.9 ± 0.3%) or RDA (0.9 ± 0.1%) groups. Daily MPS was not different (P = 0.43) between RDA (0.91 ± 0.2%/d) and 2 × RDA groups (1.13 ± 0.6%/d) during the 1-week intervention. Conclusions Daily MPS with resistance exercise training is not altered by a more protein-dense diet when at least the RDA is consumed in middle-aged adults. Our data suggest that multi-component nutritional strategies focusing on protein quality, distribution, and timing may supersede the importance of only considering total quantity to support early hypertrophic protein remodeling with resistance exercise. Funding Sources This work was supported by funds provided by the National Cattleman's Beef Association.

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Objectives Apelin is a putative exercise-sensitive myokine that has been shown to be associated with physical independence during aging. Physical performance is highly dependent on muscle strength, with a clear role of dietary protein (i.e., &gt; Recommended Dietary Allowance) for the maintenance of age-related muscle strength. However, the influence of dietary protein density on exercise-induced apelin remains unknown. Therefore, our aim was to evaluate plasma apelin concentrations and its relationship with muscle strength in middle-aged adults consuming differential amounts of animal-based protein during progressive resistance training. Methods 41 overweight middle-aged adults (50 ± 2 y, BMI 28 ± 1 kg · m−2, M = 19, F = 22) were stratified and randomized to consume either high protein (1.68 ± 0.06 g · kg−1·d−1) or moderate amounts of animal-based protein (1.16 ± 0.04 g · kg−1·d−1) during a 10-week weight-maintenance nutrition counseling-controlled resistance training program. Body composition was assessed by dual-energy x-ray absorptiometry. Muscle strength was assessed by one-repetition maximum (1RM) and isometric maximal voluntary contraction (MVC) at 60° knee angle. Oral glucose tolerance tests were performed at baseline and post-intervention. Results Main effects of time were observed for increases in lean body mass (P = 0.003), upper and lower body 1RM (all P ≤ 0.001), isometric MVC (P = 0.013), and plasma apelin concentrations (P = 0.007). There were no changes in body adiposity or glucose-insulin regulation (e.g., HOMA-IR, Matsuda) with the intervention (all P ≥ 0.152). Apelin was positively and significantly associated with isometric MVC (extension: r = 0.233, P = 0.047; flexion: r = 0.308, P = 0.008), but not 1RM. Conclusions Our results show that resistance training increases circulating apelin concentrations which is related to isometric strength gain. However, higher consumption of animal-based protein foods does not potentiate these resistance-exercise induced adaptations in overweight middle-aged adults. Funding Sources Funded in part by the Beef Checkoff. CFM funded by JBT Fellowship, UIUC.