Changes in Muscle Mass and Strength During Follow-Up After One-Year Resistance Training Interventions in Older Adults.

ABSTRACT: Mertz, KH, Reitelseder, S, Rasmussen, MA, Bülow, J, Højfeldt, G, Jensen, M, Hjulmand, M, Lindberg, J, Kramer, MU, Bechshøft, R, and Holm, L. Changes in muscle mass and strength during follow-up after one-year resistance training interventions in older adults. J Strength Cond Res 37(10): 2064-2070, 2023-The aim of this study was to investigate if home-based resistance training compared with center-based resistance training was associated with better preservation of muscle mass and strength in older individuals, 6 months after the interventions ended. One hundred four healthy older individuals (>65 years) who had completed 1 year of either home-based light-intensity training with daily whey protein supplementation (LITW), center-based heavy resistance training with whey protein supplementation (HRTW), or daily whey protein supplementation alone (WHEY) returned for follow-up measurement 6 months after the interventions. Measures of muscle mass, strength, and power were assessed at the end of intervention as well as at follow-up. Furthermore, we compared changes in these parameters between subjects who continued resistance training (≥1 weekly training session) during follow-up (CONT) with those who stopped (STOP). Resistance training continuation during follow-up did not differ between HRTW and LITW (41 vs. 41%, P = 1.0) but was higher for both groups compared with WHEY (18%, P = 0.04-0.05). However, no between-group differences were observed between LITW/HRTW/WHEY in changes in muscle mass, strength, or power during follow-up. STOP was associated with a poorer preservation of quadriceps cross-sectional area compared with CONT (-1.7 cm 2 [-0.4 to -3.0], P = 0.01, effect size: 0.79). No effect of training continuation was observed on changes in muscle strength and power. In conclusion, maintenance of muscle mass and strength is not superior after home-based resistance training compared with center-based training. However, training continuation seems crucial for the maintenance of muscle mass, irrespective of the training intervention.

Effect of 1-year daily protein supplementation and physical exercise on muscle protein synthesis rate and muscle metabolome in healthy older Danes: a randomized controlled trial.

BACKGROUND: The skeletal muscle mass decreases with age and the responsiveness of aging muscles' protein synthesis rate (MPS) to protein intake seems to deteriorate. OBJECTIVE: This study investigated the impact of 12 months of protein supplementation with or without physical exercise training on the basal and postprandial MPS and the skeletal muscle metabolome of healthy older Danes (> 65 years, 29 females/37 males). METHODS: Subjects were randomized to follow one of five intervention groups: (1) carbohydrate, (2) collagen protein, (3) whey protein, (4) home-based light resistance training with whey protein, and (5) center-based heavy-load resistance training with whey protein. Before and after the intervention, a tracer infusion trial was conducted to measure basal and postprandial MPS in response to intake of a cocktail consisting of 20 g whey hydrolysate + 10 g glucose. In addition, the skeletal muscle metabolome was measured using gas chromatography-mass spectrometry (GC-MS) at basal state and 4 h after the intake of the cocktail. RESULTS: One year of daily protein or carbohydrate supplementation did not alter the basal and protein-stimulated postprandial muscle protein synthesis rate or the muscle metabolome of healthy older Danes. Basal MPS (%/h) at baseline for all subjects were 0.0034 ± 0,011 (mean ± SD). In contrast to previous studies, no difference was observed in basal MPS between males and females (p = 0.75). With the developed untargeted GC-MS methodology, it was possible to detect and tentatively annotate > 70 metabolites from the human skeletal muscle samples. CONCLUSION: One year of protein supplementation in comparison to an isocaloric-control supplement seems to affect neither the MPS at basal or postprandial state nor the skeletal muscle metabolome. CLINICAL TRIAL REGISTRY: Number: NCT02115698, clinicaltrials.gov/ct2/show/NCT02115698.

The effect of daily protein supplementation, with or without resistance training for 1 year, on muscle size, strength, and function in healthy older adults: A randomized controlled trial.

BACKGROUND: Protein supplementation alone or combined with resistance training has been proposed to be effective in counteracting age-related losses of muscle mass and strength. OBJECTIVES: To investigate the effect of protein supplementation alone or combined with light-intensity or heavy-load resistance exercise on muscle size, strength, and function in older adults. METHODS: In a 1-y randomized controlled trial, 208 healthy older adults (>65 y) were randomly assigned to 1 of 5 interventions: 1) carbohydrate supplementation (CARB); 2) collagen protein supplementation (COLL); 3) whey protein supplementation (WHEY); 4) light-intensity resistance training 3-5 times/wk with whey protein supplementation (LITW); and 5) heavy resistance training 3 times weekly with whey protein supplementation (HRTW). Protein supplements contained 20 g protein + 10 g carbohydrate, whereas CARB contained 30 g of carbohydrates. All intervention groups received the supplement twice daily. The primary outcome was change in the quadriceps cross-sectional area (qCSA). Secondary outcomes included measures of lower extremity strength and power, functional capabilities, and body composition. RESULTS: There were 184 participants who completed the study. COLL and WHEY did not affect any measured parameter compared to CARB. Compared to WHEY, HRTW improved the qCSA size (between-group difference, +1.68 cm2; 95% CI, +0.41 to +2.95 cm2; P = 0.03), as well as dynamic (+18.4 Nm; 95% CI, +10.1 to +26.6 Nm; P < 10-4) and isometric knee extensor strength (+23.9 Nm; 95% CI, +14.2 to +33.6 Nm; P < 10-5). LITW did not improve the qCSA size, but increased dynamic knee extensor strength compared to WHEY (+13.7 Nm; 95% CI, +5.3 and +22.1 Nm; P = 0.01). CONCLUSIONS: Recommending protein supplementation as a stand-alone intervention for healthy older individuals seems ineffective in improving muscle mass and strength. Only HRTW was effective in both preserving muscle mass and increasing strength. Thus, we recommend that future studies investigate strategies to increase long-term compliance to heavy resistance exercise in healthy older adults. This trial was registered at clinicaltrials.gov as NCT02034760.

Effects of Prolonged Whey Protein Supplementation and Resistance Training on Biomarkers of Vitamin B12 Status: A 1-Year Randomized Intervention in Healthy Older Adults (the CALM Study).

We investigated the effect of long-term whey supplementation on biomarkers of B12 status in healthy older adults subjected to different schemes of supplements and exercise. The total study population examined at baseline consisted of 167 healthy older adults (age ≥ 65 year) who were randomized to 1-y intervention with two daily supplements of (1) whey protein (3.1 µg B12/day) (WHEY-ALL), (2) collagen (1.3 µg B12/day) (COLL), or (3) maltodextrin (0.3 µg B12/day) (CARB). WHEY-ALL was comprised of three groups, who performed heavy resistance training (HRTW), light resistance training (LITW), or no training (WHEY). Dietary intake was assessed through 3-d dietary records. For the longitudinal part of the study, we included only the participants (n = 110), who met the criteria of ≥ 50% compliance to the nutritional intervention and ≥ 66% and ≥ 75% compliance to the heavy and light training, respectively. Fasting blood samples collected at baseline and 12 months and non-fasting samples collected at 6 and 18 months were examined for methylmalonic acid, B12 and holotranscobalamin. At baseline, the study population (n = 167) had an overall adequate dietary B12 intake of median (range) 5.3 (0.7-65) µg/day and median B12 biomarker values within reference intervals. The whey intervention (WHEY-ALL) caused an increase in B12 (P < 0.0001) and holotranscobalamin (P < 0.0001). In addition, methylmalonic acid decreased in the LITW group (P = 0.04). No change in B12 biomarkers was observed during the intervention with collagen or carbohydrate, and the training schedules induced no changes. In conclusion, longer-term daily whey intake increased plasma B12 and holotranscobalamin in older individuals. No effect of intervention with collagen or carbohydrate or different training regimes was observed. Interestingly, the biomarkers of B12 status appeared to be affected by fasting vs. non-fasting conditions during sample collection.