Resistance Exercise In Young Men Research Articles

The Effect of Leucine-Enriched Essential Amino Acid Supplementation on Anabolic and Catabolic Signaling in Human Skeletal Muscle after Acute Resistance Exercise: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Comparison Trial.

Resistance exercise transiently activates anabolic and catabolic systems in skeletal muscle. Leucine-enriched essential amino acids (LEAAs) are reported to stimulate the muscle anabolic response at a lower dose than whey protein. However, little is known regarding the effect of LEAA supplementation on the resistance exercise-induced responses of the anabolic and catabolic systems. Here, we conducted a randomized, double-blind, placebo-controlled, parallel-group comparison trial to investigate the effect of LEAA supplementation on mechanistic target of rapamycin complex 1 (mTORC1), the ubiquitin–proteasome system and inflammatory cytokines after a single bout of resistance exercise in young men. A total of 20 healthy young male subjects were supplemented with either 5 g of LEAA or placebo, and then they performed 10 reps in three sets of leg extensions and leg curls (70% one-repetition maximum). LEAA supplementation augmented the phosphorylation of mTORSer2448 (+77.1%, p < 0.05), p70S6KThr389 (+1067.4%, p < 0.05), rpS6Ser240/244 (+171.3%, p < 0.05) and 4EBP1Thr37/46 (+33.4%, p < 0.05) after resistance exercise. However, LEAA supplementation did not change the response of the ubiquitinated proteins, MuRF-1 and Atrogin-1 expression. Additionally, the mRNA expression of IL-1β and IL-6 did not change. These data indicated that LEAA supplementation augments the effect of resistance exercise by enhancing mTORC1 signal activation after exercise.

Whole egg, but not egg white, ingestion induces mTOR colocalization with the lysosome after resistance exercise.

We have recently demonstrated that whole egg ingestion induces a greater muscle protein synthetic (MPS) response when compared with isonitrogenous egg white ingestion after resistance exercise in young men. Our aim was to determine whether whole egg or egg white ingestion differentially influenced colocalization of key regulators of mechanistic target of rapamycin complex 1 (mTORC1) as means to explain our previously observed divergent postexercise MPS response. In crossover trials, 10 healthy resistance-trained men (21 ± 1 yr; 88 ± 3 kg; body fat: 16 ± 1%; means ± SE) completed lower body resistance exercise before ingesting whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Muscle biopsies were obtained before exercise and at 120 and 300 min after egg ingestion to assess, by immunofluorescence, protein colocalization of key anabolic signaling molecules. After resistance exercise, tuberous sclerosis 2-Ras homolog enriched in brain (Rheb) colocalization decreased ( P < 0.01) at 120 and 300 min after whole egg and egg white ingestion with concomitant increases ( P < 0.01) in mTOR-Rheb colocalization. After resistance exercise, mTOR-lysosome-associated membrane protein 2 (LAMP2) colocalization significantly increased at 120 and 300 min only after whole egg ingestion ( P < 0.01), and mTOR-LAMP2 colocalization correlated with rates of MPS at rest and after exercise ( r = 0.40, P < 0.05). We demonstrated that the greater postexercise MPS response with whole egg ingestion is related in part to an enhanced recruitment of mTORC1-Rheb complexes to the lysosome during recovery. These data suggest nonprotein dietary factors influence the postexercise regulation of mRNA translation in human skeletal muscle.

Beta2 -adrenoceptor agonist salbutamol increases protein turnover rates and alters signalling in skeletal muscle after resistance exercise in young men.

Animal models have shown that beta2 -adrenoceptor stimulation increases protein synthesis and attenuates breakdown processes in skeletal muscle. Thus, the beta2 -adrenoceptor is a potential target in the treatment of disuse-, disease- and age-related muscle atrophy. In the present study, we show that a few days of oral treatment with the commonly prescribed beta2 -adrenoceptor agonist, salbutamol, increased skeletal muscle protein synthesis and breakdown during the first 5h after resistance exercise in young men. Salbutamol also counteracted a negative net protein balance in skeletal muscle after resistance exercise. Changes in protein turnover rates induced by salbutamol were associated with protein kinase A-signalling, activation of Akt2 and modulation of mRNA levels of growth-regulating proteins in skeletal muscle. These findings indicate that protein turnover rates can be augmented by beta2 -adrenoceptor agonist treatment during recovery from resistance exercise in humans. The effect of beta2 -adrenoceptor stimulation on skeletal muscle protein turnover and intracellular signalling is insufficiently explored in humans, particularly in association with exercise. In a randomized, placebo-controlled, cross-over study investigating 12 trained men, the effects of beta2 -agonist (6×4mg oral salbutamol) on protein turnover rates, intracellular signalling and mRNA response in skeletal muscle were investigated 0.5-5h after quadriceps resistance exercise. Each trial was preceded by a 4-day lead-in treatment period. Leg protein turnover rates were assessed by infusion of [13 C6 ]-phenylalanine and sampling of arterial and venous blood, as well as vastus lateralis muscle biopsies 0.5 and 5h after exercise. Furthermore, myofibrillar fractional synthesis rate, intracellular signalling and mRNA response were measured in muscle biopsies. The mean (95% confidence interval) myofibrillar fractional synthesis rate was higher for salbutamol than placebo [0.079(95% CI, 0.064 to 0.093) vs. 0.066(95% CI, 0.056 to 0.075%)×h-1 ] (P<0.05). Mean net leg phenylalanine balance 0.5-5h after exercise was higher for salbutamol than placebo [3.6(95% CI, 1.0 to 6.2nmol)×min-1 ×100 gLeg Lean Mass-1 ] (P<0.01). Phosphorylation of Akt2, cAMP response element binding protein and PKA substrate 0.5 and 5h after exercise, as well as phosphorylation of eEF2 5h after exercise, was higher (P<0.05) for salbutamol than placebo. Calpain-1, Forkhead box protein O1, myostatin and Smad3 mRNA content was higher (P<0.01) for salbutamol than placebo 0.5h after exercise, as well as Forkhead box protein O1 and myostatin mRNA content 5h after exercise, whereas ActivinRIIB mRNA content was lower (P<0.01) for salbutamol 5h after exercise. These observations suggest that beta2 -agonist increases protein turnover rates in skeletal muscle after resistance exercise in humans, with concomitant cAMP/PKA and Akt2 signalling, as well as modulation of mRNA response of growth-regulating proteins.

Intensive resistance exercise and circadian salivary testosterone concentrations among young male recreational lifters.

Strength and morphological adaptations to resistance exercise are mediated in part by anabolic hormones such as testosterone, yet the time course of variability in circadian hormone concentrations is not well characterized. This study, investigated how the circadian rhythm of salivary testosterone is altered by resistance exercise in young men. Twenty healthy young male recreational lifters (age, 18.0 ± 1.3 years) with 2 years of experience in weightlifting were recruited. A randomized controlled trial was conducted, and subjects were randomly assigned to either the resistance exercise group (n = 10), who completed a series of resistance exercise (3 times a week, in the afternoon, 6-7 repetitions, at 85% of 1 repetition maximum for 3 weeks), or a control group (n = 10), who did not exercise during the 3 weeks. Before and after the study, an unstimulated saliva sample (2 ml) was taken every 2 hours for a maximum of 16 hours during each day. A significant decrease was observed in the resistance exercise (44.2%, p = 0.001) and control group (46.1%, p = 0.001) for salivary testosterone at each time point compared with baseline (p = 0.001). There was also no significant difference between the exercise and resting conditions in both groups for salivary testosterone (p > 0.05), except a significantly higher increase by 38.4% vs. -0.02% (p = 0.001), at 1730 hours during exercise sessions in the resistance exercise group compared with the control group. Resistance exercise has no noteworthy effect on circadian secretion of salivary testosterone throughout the 16 waking hours. These results indicate that athletes can undertake resistance exercise in either the morning or afternoon with the knowledge that a similar testosterone response can be expected regardless of the time of day.

The curious case of anabolic resistance: old wives' tales or new fables?

the progressive loss of muscle mass, commonly termed sarcopenia, accompanies the process of healthy aging ([27][1]). The underlying basis of this condition, in a very simplistic view, would be at a more advanced age skeletal muscle proteins are being lost because of an imbalance between muscle

Hormone Responses to Acute and Chronic Traditional and Blood Flow Restricted Resistance Exercise in Young Men

Hormone Responses to Acute and Chronic Traditional and Blood Flow Restricted Resistance Exercise in Young Men

Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men

BackgroundWe aimed to determine the effect of resistance exercise intensity (% 1 repetition maximum—1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression.Methodology/Principal FindingsFifteen men (21±1 years; BMI = 24.1±0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.Conclusions/SignificanceThese results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.

Correction: Farnfield, M.M., et al. Whey Protein Ingestion Activates mTOR-dependent Signalling after Resistance Exercise in Young Men: A Double-Blinded Randomized Controlled Trial. Nutrients 2009, 1, 263-275.

We found an error in our paper recently published in Nutrients [1]. [...]

Whey Protein Ingestion Activates mTOR-dependent Signalling after Resistance Exercise in Young Men: A Double-Blinded Randomized Controlled Trial

The effect of resistance exercise with the ingestion of supplementary protein on the activation of the mTOR cascade, in human skeletal muscle has not been fully elucidated. In this study, the impact of a single bout of resistance exercise, immediately followed by a single dose of whey protein isolate (WPI) or placebo supplement, on the activation of mTOR signalling was analyzed. Young untrained men completed a maximal single-legged knee extension exercise bout and were randomized to ingest either WPI supplement (n = 7) or the placebo (n = 7). Muscle biopsies were taken from the vastus lateralis before, and 2, 4 and 24 h post-exercise. WPI or placebo ingestion consumed immediately post-exercise had no impact on the phosphorylation of Akt (Ser473). However, WPI significantly enhanced phosphorylation of mTOR (Ser2448), 4E-BP1 (Thr37/46) and p70S6K (Thr389) at 2 h post-exercise. This study demonstrates that a single dose of WPI, when consumed in modest quantities, taken immediately after resistance exercise elicits an acute and transient activation of translation initiation within the exercised skeletal muscle.

Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men

This study was designed to compare the acute response of mixed muscle protein synthesis (MPS) to rapidly (i.e., whey hydrolysate and soy) and slowly (i.e., micellar casein) digested proteins both at rest and after resistance exercise. Three groups of healthy young men (n = 6 per group) performed a bout of unilateral leg resistance exercise followed by the consumption of a drink containing an equivalent content of essential amino acids (10 g) as either whey hydrolysate, micellar casein, or soy protein isolate. Mixed MPS was determined by a primed constant infusion of l-[ring-(13)C(6)]phenylalanine. Ingestion of whey protein resulted in a larger increase in blood essential amino acid, branched-chain amino acid, and leucine concentrations than either casein or soy (P < 0.05). Mixed MPS at rest (determined in the nonexercised leg) was higher with ingestion of faster proteins (whey = 0.091 +/- 0.015, soy = 0.078 +/- 0.014, casein = 0.047 +/- 0.008%/h); MPS after consumption of whey was approximately 93% greater than casein (P < 0.01) and approximately 18% greater than soy (P = 0.067). A similar result was observed after exercise (whey > soy > casein); MPS following whey consumption was approximately 122% greater than casein (P < 0.01) and 31% greater than soy (P < 0.05). MPS was also greater with soy consumption at rest (64%) and following resistance exercise (69%) compared with casein (both P < 0.01). We conclude that the feeding-induced simulation of MPS in young men is greater after whey hydrolysate or soy protein consumption than casein both at rest and after resistance exercise; moreover, despite both being fast proteins, whey hydrolysate stimulated MPS to a greater degree than soy after resistance exercise. These differences may be related to how quickly the proteins are digested (i.e., fast vs. slow) or possibly to small differences in leucine content of each protein.

Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men

BackgroundThe anabolic effect of resistance exercise is enhanced by the provision of dietary protein. ObjectivesWe aimed to determine the ingested protein dose response of muscle (MPS) and albumin protein synthesis (APS) after resistance exercise. In addition, we measured the phosphorylation of candidate signaling proteins thought to regulate acute changes in MPS. DesignSix healthy young men reported to the laboratory on 5 separate occasions to perform an intense bout of leg-based resistance exercise. After exercise, participants consumed, in a randomized order, drinks containing 0, 5, 10, 20, or 40 g whole egg protein. Protein synthesis and whole-body leucine oxidation were measured over 4 h after exercise by a primed constant infusion of [1-13C]leucine. ResultsMPS displayed a dose response to dietary protein ingestion and was maximally stimulated at 20 g. The phosphorylation of ribosomal protein S6 kinase (Thr389), ribosomal protein S6 (Ser240/244), and the ε-subunit of eukaryotic initiation factor 2B (Ser539) were unaffected by protein ingestion. APS increased in a dose-dependent manner and also reached a plateau at 20 g ingested protein. Leucine oxidation was significantly increased after 20 and 40 g protein were ingested. ConclusionsIngestion of 20 g intact protein is sufficient to maximally stimulate MPS and APS after resistance exercise. Phosphorylation of candidate signaling proteins was not enhanced with any dose of protein ingested, which suggested that the stimulation of MPS after resistance exercise may be related to amino acid availability. Finally, dietary protein consumed after exercise in excess of the rate at which it can be incorporated into tissue protein stimulates irreversible oxidation.

Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men

Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men

Arterial stiffness following repeated Valsalva maneuvers and resistance exercise in young men

The purpose of this study was to compare arterial stiffness after a bout of resistance exercise (RE) and an experimental condition consisting of repeated Valsalva maneuvers (VMs). Fourteen male participants randomly completed a lower-body, unilateral RE bout and a VM bout designed to alter blood pressure (BP) in a similar pulsatile fashion. Pulse-wave velocity (PWV, measured in metres per second (m.s-1)) was used to measure central and peripheral arterial stiffness and was assessed before and 20 min after each perturbation. Beat-to-beat blood pressure (BP) was assessed during bouts using finger plethysmography. Change in systolic BP, diastolic BP, mean arterial pressure, and pulse pressure were similar during both bouts. Central PWV increased after repeated VMs (7.1 +/- 0.3 m/s to 7.8 +/- 0.3 m/s), but not after RE (7.2 +/- 0.3 m/s to 7.2 +/- 0.3 m/s) (interaction, p = 0.032). There was no change in peripheral PWV after VM (8.9 +/- 0.3 m/s to 9.3 +/- 0.3 m/s) or RE (8.5 +/- 0.2 m/s to 8.4 +/- 0.2 m/s). Arterial stiffness increased after repeated VM. Even though presented with a similar BP load, arterial stiffness did not increase after acute RE. These findings suggest a role for VM in acutely altering arterial properties.

Dose‐responses of whole body protein turnover with increasing protein intake after an acute bout of resistance exercise in young men

Dose‐responses of whole body protein turnover with increasing protein intake after an acute bout of resistance exercise in young men

Minimal whey protein with carbohydrate stimulates muscle protein synthesis following resistance exercise in young men.

Whey protein is a supplemental protein source used by athletes, particularly those aiming to gain muscle mass; however, direct evidence for its efficacy in stimulating muscle protein synthesis (MPS) is lacking. We aimed to determine the impact of consuming whey protein on skeletal muscle protein turnover in the post-exercise period. Eight healthy young men (BMI = 26.8±0.9; age = 21±1) participated in a double-blind randomized cross-over trial in which they performed a unilateral leg resistance exercise workout – EX – (4 sets of knee extensions and 4 sets of leg press – 8–10 reps per set), such that the other leg was not exercised and acted as a rested (RE) comparator. After exercise subjects consumed either an isocaloric whey protein plus carbohydrate beverage (10g whey and 21g fructose) – WHEY – or a carbohydrate beverage containing fructose and maltodextrin (21g and 10g, respectively) – CHO. Subjects received pulse-tracer injections of L[ring-2H5]phenylalanine and L-[15N]phenylalanine to measure MPS. Exercise stimulated a rise in MPS only in the WHEY-EX leg, which was greater than MPS in the WHEY-RE leg and also the CHO-EX leg (all P<0.01). We conclude that a small dose (10g) of whey protein with carbohydrate (21g) can stimulate a rise in MPS after resistance exercise which, overtime, would be supportive of a net muscle protein accrual and hypertrophy. Supported by the US National Dairy Council.

Dietary Protein to Support Anabolism with Resistance Exercise in Young Men

Resistance exercise is fundamentally anabolic and as such stimulates the process of skeletal muscle protein synthesis (MPS) in an absolute sense and relative to skeletal muscle protein breakdown (MPB). However, the net effect of resistance exercise is to shift net protein balance (NPB = MPS − MPB) to a more positive value; however, in the absence of feeding NPB remains negative. Feeding stimulates MPS to an extent where NPB becomes positive, for a transient time. When combined, resistance exercise and feeding synergistically interact to result in NPB being greater than with feeding alone. This feeding- and exercise-induced stimulation of NPB is what, albeit slowly, results in muscle hypertrophy. With this rudimentary knowledge we are now at the point where we can manipulate variables within the system to see what impact these interventions have on the processes of MPS, MPB, and NPB and ultimately and perhaps most importantly, muscle hypertrophy and strength. We used established models of skeletal muscle amino acid turnover to examine how protein source (milk versus soy) acutely affects the processes of MPS and MPB after resistance exercise. Our findings revealed that even when balanced quantities of total protein and energy are consumed that milk proteins are more effective in stimulating amino acid uptake and net protein deposition in skeletal muscle after resistance exercise than are hydrolyzed soy proteins. Importantly, the finding of increased amino acid uptake would be independent of the differences in amino acid composition of the two proteins. We propose that the improved net protein deposition with milk protein consumption is also not due to differences in amino acid composition, but is due to a different pattern of amino acid delivery associated with milk versus hydrolyzed soy proteins. If our acute findings are accurate then we hypothesized that chronically the greater net protein deposition associated with milk protein consumption post-resistance exercise would eventually lead to greater net protein accretion (i.e., muscle fiber hypertrophy), over a longer time period. In young men completing 12 weeks of resistance training (5d/wk) we observed a tendency (P = 0.11) for greater gains in whole body lean mass and whole as greater muscle fiber hypertrophy with consumption of milk. While strength gains were not different between the soy and milk-supplemented groups we would argue that the true significance of a greater increase in lean mass that we observed with milk consumption may be more important in groups of persons with lower initial lean mass and strength such as the elderly.