Dietary protein digestion and absorption kinetics are not impaired after exercise or at an older age. Exercising before protein intake allows for a greater use of dietary protein-derived amino acids for de novo muscle protein synthesis in both young and elderly men. This trial was registered at clinicaltrials.gov as NCT00557388.

Timed protein supplementation immediately before and after exercise does not further augment the increase in skeletal muscle mass and strength after prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein. This trial was registered at clinicaltrials.gov as NCT00744094.

This is the first study to show that protein ingested immediately before sleep is effectively digested and absorbed, thereby stimulating muscle protein synthesis and improving whole-body protein balance during postexercise overnight recovery.

During postexercise recovery, optimal nutritional intake is important to replenish endogenous substrate stores and to facilitate muscle-damage repair and reconditioning. After exhaustive endurance-type exercise, muscle glycogen repletion forms the most important factor determining the time needed to recover. Postexercise carbohydrate (CHO) ingestion has been well established as the most important determinant of muscle glycogen synthesis. Coingestion of protein and/or amino acids does not seem to further increase muscle glycogensynthesis rates when CHO intake exceeds 1.2 g · kg -1 · hr -1 . However, from a practical point of view it is not always feasible to ingest such large amounts of CHO. The combined ingestion of a small amount of protein (0.2-0.4 g · kg -1 · hr -1 ) with less CHO (0.8 g · kg -1 · hr -1 ) stimulates endogenous insulin release and results in similar muscle glycogen-repletion rates as the ingestion of 1.2 g · kg -1 · hr -1 CHO. Furthermore, postexercise protein and/or amino acid administration is warranted to stimulate muscle protein synthesis, inhibit protein breakdown, and allow net muscle protein accretion. The consumption of ~20 g intact protein, or an equivalent of ~9 g essential amino acids, has been reported to maximize muscle protein-synthesis rates during the first hours of postexercise recovery. Ingestion of such small amounts of dietary protein 5 or 6 times daily might support maximal muscle protein-synthesis rates throughout the day. Consuming CHO and protein during the early phases of recovery has been shown to positively affect subsequent exercise performance and could be of specific benefit for athletes involved in multiple training or competition sessions on the same or consecutive days.

Impaired digestion and/or absorption of dietary protein lowers postprandial plasma amino acid availability and, as such, could reduce the postprandial muscle protein synthetic response in the elderly. We aimed to compare in vivo dietary protein digestion and absorption and the subsequent postprandial muscle protein synthetic response between young and elderly men. Ten elderly (64 +/- 1 y) and 10 young (23 +/- 1 y) healthy males consumed a single bolus of 35 g specifically produced, intrinsically l-[1-(13)C]phenylalanine-labeled micellar casein (CAS) protein. Furthermore, primed continuous infusions with l-[ring-(2)H(5)]phenylalanine, l-[1-(13)C]leucine, and l-[ring-(2)H(2)]tyrosine were applied and blood and muscle tissue samples were collected to assess the appearance rate of dietary protein-derived phenylalanine in the circulation and the subsequent muscle protein fractional synthetic rate over a 6-h postprandial period. Protein ingestion resulted in a rapid increase in exogenous phenylalanine appearance in both the young and elderly men. Total exogenous phenylalanine appearance rates (expressed as area under the curve) were 39 +/- 3 mumol.6 h.kg(-1) in the young men and 38 +/- 2 mumol.6 h.kg(-1) in the elderly men (P = 0.73). In accordance, splanchnic amino acid extraction did not differ between young (72 +/- 2%) and elderly (73 +/- 1%) volunteers (P = 0.74). Muscle protein synthesis rates, calculated from the oral tracer, were 0.063 +/- 0.006 and 0.054 +/- 0.004%/h in the young and elderly men, respectively, and did not differ between groups (P = 0.27). We conclude that protein digestion and absorption kinetics and the subsequent muscle protein synthetic response following the ingestion of a large bolus of intact CAS are not substantially impaired in healthy, elderly men.

It has been reported previously that mouth rinsing with a carbohydrate-containing solution can improve cycling performance. The purpose of the current study was to investigate the impact of such a carbohydrate mouth rinse on exercise performance during a simulated time trial in a more practical, postprandial setting. Fourteen male endurance-trained athletes were selected to perform 2 exercise tests in the morning after consuming a standardized breakfast. They performed an approximately 1-hr time trial on a cycle ergometer while rinsing their mouths with either a 6.4% maltodextrin solution (CHO) or water (PLA) after every 12.5% of the set amount of work. Borg's rating of perceived exertion (RPE) was assessed after every 25% of the set amount of work, and power output and heart rate were recorded continuously throughout the test. Performance time did not differ between treatments and averaged 68.14 +/- 1.14 and 67.52 +/- 1.00 min in CHO and PLA, respectively (p = .57). In accordance, average power output (265 +/- 5 vs. 266 +/- 5 W,p = .58), heart rate (169 +/- 2 vs. 168 +/- 2 beats/min, p = .43), and RPE (16.4 +/- 0.3 vs. 16.7 +/- 0.3 W, p = .26) did not differ between treatments. Furthermore, after dividing the trial into 8 s, no differences in power output, heart rate, or perceived exertion were observed over time between treatments. Carbohydrate mouth rinsing does not improve time-trial performance when exercise is performed in a practical, postprandial setting.

Aims/hypothesis Exercise represents an effective interventional strategy to improve glycaemic control in type 2 diabetes patients. However, the impact of exercise intensity on the benefits of exercise training remains to be established. In the present study, we compared the clinical benefits of 6 months of continuous low-to moderate-intensity exercise training with those of continuous moderate-to high-intensity exercise training, matched for energy expenditure, in obese type 2 diabetes patients.Methods Fifty male obese type 2 diabetes patients (age 59± 8 years, BMI 32±4 kg/m 2 ) participated in a 6 month continuous endurance-type exercise training programme. All participants performed three supervised exercise sessions per week, either 55 min at 50% of whole body peak oxygen uptake V Á O 2peak À Á (low to moderate intensity) or 40 min at 75% of V Á O 2peak (moderate to high intensity). Oral glucose tolerance, blood glycated haemoglobin, lipid profile, body composition, maximal workload capacity, whole body and skeletal muscle oxidative capacity and skeletal muscle fibre type composition were assessed before and after 2 and 6 months of intervention. Results The entire 6 month intervention programme was completed by 37 participants. Continuous endurance-type exercise training reduced blood glycated haemoglobin levels, LDL-cholesterol concentrations, body weight and leg fat mass, and increased V Á O 2peak , lean muscle mass and skeletal muscle cytochrome c oxidase and citrate synthase activity (p<0.05). No differences were observed between the groups training at low to moderate or moderate to high intensity. Conclusions/interpretation When matched for energy cost, prolonged continuous low-to moderate-intensity endurancetype exercise training is equally effective as continuous moderate-to high-intensity training in lowering blood glycated haemoglobin and increasing whole body and skeletal muscle oxidative capacity in obese type 2 diabetes patients.

The present study was designed to assess the impact of coingestion of various amounts of carbohydrate combined with an ample amount of protein intake on postexercise muscle protein synthesis rates. Ten healthy, fit men (20 Ϯ 0.3 yr) were randomly assigned to three crossover experiments. After 60 min of resistance exercise, subjects consumed 0.3 g ⅐ kg Ϫ1 ⅐ h Ϫ1 protein hydrolysate with 0, 0.15, or 0.6 g ⅐ kg Ϫ1 ⅐ h Ϫ1 carbohydrate during a 6-h recovery period (PRO, PRO ϩ LCHO, and PRO ϩ HCHO, respectively). Primed, continuous infusions with L-[ring-13 C6]phenylalanine, L-[ring-2 H2]tyrosine, and [6,6-2 H2]glucose were applied, and blood and muscle samples were collected to assess whole body protein turnover and glucose kinetics as well as protein fractional synthesis rate (FSR) in the vastus lateralis muscle over 6 h of postexercise recovery. Plasma insulin responses were significantly greater in PRO ϩ HCHO compared with PRO ϩ LCHO and PRO (18.4 Ϯ 2.9 vs. 3.7 Ϯ 0.5 and 1.5 Ϯ 0.2 U ⅐ 6 h Ϫ1 ⅐ l Ϫ1 , respectively, P Ͻ 0.001). Plasma glucose rate of appearance (Ra) and disappearance (Rd) increased over time in PRO ϩ HCHO and PRO ϩ LCHO, but not in PRO. Plasma glucose Ra and R d were substantially greater in PRO ϩ HCHO vs. both PRO and PRO ϩ LCHO (P Ͻ 0.01). Whole body protein breakdown, synthesis, and oxidation rates, as well as whole body protein balance, did not differ between experiments. Mixed muscle protein FSR did not differ between treatments and averaged 0.10 Ϯ 0.01, 0.10 Ϯ 0.01, and 0.11 Ϯ 0.01%/h in the PRO, PRO ϩ LCHO, and PRO ϩ HCHO experiments, respectively. In conclusion, coingestion of carbohydrate during recovery does not further stimulate postexercise muscle protein synthesis when ample protein is ingested. resistance exercise; protein metabolism; nutrition; recovery POSTEXERCISE NUTRITION IS INSTRUMENTAL to enhance recovery and to facilitate the adaptive response to regular exercise training (28). In the endurance-trained athlete, rapid restoration of depleted muscle glycogen stores is essential to enhance postexercise recovery and, as such, to maintain performance capacity (15). Therefore, endurance athletes generally aim to maximize postexercise muscle glycogen synthesis rates by ingesting large amounts of carbohydrate during recovery (30,40). Coingestion of relative small amounts of protein and/or amino acids has been suggested to further accelerate muscle glycogen repletion and/or to reduce muscle damage (40, 44).It has been firmly established (4,18,19,23,25) that postexercise protein and/or amino acid intake is essential to allow net muscle protein accretion. Therefore, athletes involved in resistance-type exercise training like fitness and bodybuilding generally ingest large quantities of protein during postexercise recovery to augment net muscle protein accretion (21, 38). It is generally assumed that carbohydrate should be coingested to maximize the postexercise muscle protein synthetic response. Although ingestion of only carbohydrate does not seem to stimulate postexercise muscle protein...