Protein Supplementation after Exercise and before Sleep Does Not Further Augment Muscle Mass and Strength Gains during Resistance Exercise Training in Active Older Men.

Background: The proposed benefits of protein supplementation on the skeletal muscle adaptive response to resistance exercise training in older adults remain unclear. Objective: The present study assessed whether protein supplementation after exercise and before sleep augments muscle mass and strength gains during resistance exercise training in older individuals. Methods: Forty-one older men [mean ± SEM age: 70 ± 1 y; body mass index (kg/m2): 25.3 ± 0.4] completed 12 wk of whole-body resistance exercise training (3 sessions/wk) and were randomly assigned to ingest either protein (21 g protein, 3 g total leucine, 9 g carbohydrate, 3 g fat; n = 21) or an energy-matched placebo (0 g protein, 25 g carbohydrate, 6 g fat; n = 20) after exercise and each night before sleep. Maximal strength was assessed by 1-repetition-maximum (1RM) strength testing, and muscle hypertrophy was assessed at the whole-body (dual-energy X-ray absorptiometry), upper leg (computed tomography scan), and muscle fiber (biopsy) levels. Muscle protein synthesis rates were assessed during week 12 of training with the use of deuterated water (2H2O) administration. Results: Leg-extension 1RM increased in both groups (placebo: 88 ± 3 to 104 ± 4 kg; protein: 85 ± 3 to 102 ± 4 kg; P < 0.001), with no differences between groups. Quadriceps cross-sectional area (placebo: 67.8 ± 1.7 to 73.5 ± 2.0 cm2; protein: 68.4 ± 1.4 to 72.3 ± 1.4 cm2; P < 0.001) increased in both groups, with no differences between groups. Muscle fiber hypertrophy occurred in type II muscle fibers (placebo: 5486 ± 418 to 6492 ± 429 µm2; protein: 5367 ± 301 to 6259 ± 391 µm2; P < 0.001), with no differences between groups. Muscle protein synthesis rates were 1.62% ± 0.06% and 1.57% ± 0.05%/d in the placebo and protein groups, respectively, with no differences between groups. Conclusion: Protein supplementation after exercise and before sleep does not further augment skeletal muscle mass or strength gains during resistance exercise training in active older men. This study was registered at the Netherlands Trial Registry (www.trialregister.nl) as NTR5082.

Nandrolone decanoate administration does not attenuate muscle atrophy during a short period of disuse.

BACKGROUND: A few days of bed rest or immobilization following injury, disease, or surgery can lead to considerable loss of skeletal muscle mass and strength. It has been speculated that such short, successive periods of muscle disuse may be largely responsible for the age-related loss of muscle mass throughout the lifespan. OBJECTIVE: To assess whether a single intramuscular injection of nandrolone decanoate prior to immobilization can attenuate the loss of muscle mass and strength in vivo in humans. DESIGN, SETTING AND PARTICIPANTS: Thirty healthy (22 ± 1 years) men were subjected to 7 days of one-legged knee immobilization by means of a full leg cast with (NAD, n = 15) or without (CON, n = 15) prior intramuscular nandrolone decanoate injection (200 mg). MEASURES: Before and immediately after immobilization, quadriceps muscle cross-sectional area (CSA) (by means of single-slice computed tomography (CT) scans of the upper leg) and one-legged knee extension strength (one-repetition maximum [1-RM]) were assessed for both legs. Furthermore, muscle biopsies from the immobilized leg were taken before and after immobilization to assess type I and type II muscle fiber cross-sectional area. RESULTS: Quadriceps muscle CSA decreased during immobilization in both CON and NAD (-6 ± 1% and -6 ± 1%, respectively; main effect of time P<0.01), with no differences between the groups (time × treatment interaction, P = 0.59). Leg muscle strength declined following immobilization (-6 ± 2% in CON and -7 ± 3% in NAD; main effect of time, P<0.05), with no differences between groups (time × treatment interaction, P = 0.55). CONCLUSIONS: This is the first study to report that nandrolone decanoate administration does not preserve skeletal muscle mass and strength during a short period of leg immobilization in vivo in humans.

Leucine Supplementation Does Not Attenuate Skeletal Muscle Loss during Leg Immobilization in Healthy, Young Men.

BACKGROUND: Short successive periods of physical inactivity occur throughout life and contribute considerably to the age-related loss of skeletal muscle mass. The maintenance of muscle mass during brief periods of disuse is required to prevent functional decline and maintain metabolic health. OBJECTIVE: To assess whether daily leucine supplementation during a short period of disuse can attenuate subsequent muscle loss in vivo in humans. METHODS: Thirty healthy (22 ± 1 y) young males were exposed to a 7-day unilateral knee immobilization intervention by means of a full leg cast with (LEU, n = 15) or without (CON, n = 15) daily leucine supplementation (2.5 g leucine, three times daily). Prior to and directly after immobilization, quadriceps muscle cross-sectional area (computed tomography (CT) scan) and leg strength (one-repetition maximum (1-RM)) were assessed. Furthermore, muscle biopsies were taken in both groups before and after immobilization to assess changes in type I and type II muscle fiber CSA. RESULTS: Quadriceps muscle cross-sectional area (CSA) declined in the CON and LEU groups (p < 0.01), with no differences between the two groups (from 7712 ± 324 to 7287 ± 305 mm² and from 7643 ± 317 to 7164 ± 328 mm²; p = 0.61, respectively). Leg muscle strength decreased from 56 ± 4 to 53 ± 4 kg in the CON group and from 63 ± 3 to 55 ± 2 kg in the LEU group (main effect of time p < 0.01), with no differences between the groups (p = 0.052). Type I and II muscle fiber size did not change significantly over time, in both groups (p > 0.05). CONCLUSIONS: Free leucine supplementation with each of the three main meals (7.5 g/d) does not attenuate the decline of muscle mass and strength during a 7-day limb immobilization intervention.

Creatine Loading Does Not Preserve Muscle Mass or Strength During Leg Immobilization in Healthy, Young Males: A Randomized Controlled Trial.

BACKGROUND: A short period of leg immobilization leads to rapid loss of muscle mass and strength. Creatine supplementation has been shown to increase lean body mass in active individuals and can be used to augment gains in muscle mass and strength during prolonged resistance-type exercise training. OBJECTIVE: Our objective was to investigate whether creatine loading can attenuate the loss of muscle mass and strength during short-term leg immobilization. METHODS: Healthy young men (n = 30; aged 23 ± 1 years; body mass index [BMI] 23.3 ± 0.5 kg/m-2) were randomly assigned to either a creatine or a placebo group. Subjects received placebo or creatine supplements (20 g/d) for 5 days before one leg was immobilized by means of a full-leg cast for 7 days. Muscle biopsies were taken before creatine loading, prior to and immediately after leg immobilization, and after 7 days of subsequent recovery. Quadriceps cross-sectional area (CSA) (computed tomography [CT] scan) and leg muscle strength (one-repetition maximum [1-RM] knee extension) were assessed before and immediately after immobilization and after 1 week of recovery. Data were analyzed using repeated measures analysis of variance (ANOVA). Data are presented consistently as mean ± standard error of the mean (SEM). RESULTS: There was a significant overall increase in muscle total creatine content following the 5-day loading phase (p = 0.049), which appeared driven by an increase in the creatine group (from 90 ± 9 to 107 ± 4 mmol/kg-1 dry muscle) with no apparent change in the placebo group (from 88 ± 4 to 90 ± 3 mmol/kg-1; p = 0.066 for time × treatment interaction). Quadriceps muscle CSA had declined by 465 ± 59 and 425 ± 69 mm2 (p < 0.01) in the creatine and placebo group, respectively, with no differences between groups (p = 0.76). Leg muscle strength decreased from 56 ± 4 to 53 ± 4 kg in the creatine and from 59 ± 3 to 53 ± 3 kg in the placebo group, with no differences between groups (p = 0.20). Muscle fiber size did not change significantly over time in either group (p > 0.05). When non-responders to creatine loading were excluded (n = 6), responders (n = 8; total creatine content increasing from 70 to 106 mmol/kg-1) showed similar findings, with no signs of preservation of muscle mass or strength during immobilization. During the subsequent recovery phase, no differences in muscle mass or strength were found between the two groups (p > 0.05). CONCLUSION: Creatine supplementation prior to and during leg immobilization does not prevent or attenuate the loss of muscle mass or strength during short-term muscle disuse. NIH Clinical Trial Registration Number: NCT01894737 ( http://www.clinicaltrials.gov/ ).