Effects of resistance training and protein supplementation interventions on muscle volume and muscle function: sex differences in humans

Comparison of the Effectiveness of Protein Supplementation Combined with Resistance Training on Body Composition and Physical Function in Healthy Elderly Adults

BACKGROUND

The global population of individuals over 65 y is expected to reach 426 million by 2050. Aging is associated with a progressive loss of muscle mass, strength, and function, leading to sarcopenia and adverse outcomes such as physical disability and increased mortality. Interventions such as resistance training and protein supplementation have shown promise in mitigating these effects.

OBJECTIVES

To determine the comparative effectiveness of protein supplementation, resistance training, and their combination on body composition and physical function in healthy older adults through a network meta-analysis.

METHODS

We conducted a systematic review and network meta-analysis following PRISMA guidelines and registered it in PROSPERO (CRD42021226561). We included randomized controlled trials comparing protein supplementation, resistance training, and their combination in participants aged ≥50 y. Data were extracted from PubMed, Web of Science, Embase, and Cochrane Library. The risk of bias was assessed using the Cochrane Collaboration Risk of Bias Tool.

RESULTS

A total of 38 randomized controlled trials involving 2610 participants were included. The combined intervention of protein supplementation and resistance training significantly improved lean body mass (standardized mean difference [SMD]: 0.44; 95% confidence interval [CI]: 0.05, 0.95) compared with protein supplementation alone. The combined intervention also showed significant improvements in muscle mass (SMD: 1.49; 95% CI: 0.11, 2.67). The combined intervention (SMD: 2.74; 95% CI: 0.76, 4.74) and resistance training alone (SMD: 2.53, 95% CI: 0.29, 4.84) significantly improved muscle strength compared with controls. The combined intervention (SMD: 4.98; 95% CI: 2.72, 7.17) and resistance training alone (SMD: 4.52; 95% CI: 2.30, 6.64) significantly improved physical function compared with protein supplementation alone.

CONCLUSIONS

Combining exercise and protein supplementation is the most effective method for improving muscle mass, strength, and physical function in older adults. This approach should be considered to enhance physical health in this population. Future large-scale trials are necessary to confirm these findings.

Maximal Oxygen Uptake, Muscular Oxidative Capacity, and Ventilatory Threshold in Amateur Triathletes: Eight-Month Training Follow-Up

Purpose

Endurance sports performance is influenced by several factors, including maximal oxygen uptake (⩒O2max), the percentage of ⩒O2max that can be sustained in endurance events, running economy, and body composition. Traditionally, ⩒O2max can be measured as an absolute value, adjusted for body mass, reflecting the athlete's central capacity (maximal cardiac output), or adjusted for lean mass (LM), reflecting the athlete's peripheral capacity (muscular oxidative capacity). The present study aims to evaluate absolute, total body mass, and lower limb LM-adjusted ⩒O2max, ventilatory thresholds (VT), respiratory compensation points (RCP), and body composition during two training periods separated by 8 months.

Patients and Methods

Thirteen competitive amateur triathletes [seven men (40.7±13.7 years old, 76.3±8.3kg, and 173.9±4.8cm) and six women (43.5±6.9 years old, 55.0±2.7kg, 164.9±5.2cm)] were evaluated for body composition with dual-energy X-ray absorptiometry and ⩒O2max, VT, RPC, and maximal aerobic speed (MAS) with a cardiorespiratory maximal treadmill test.

Results

The absolute ⩒O2max (p = 0.003, d = 1.05), body mass-adjusted ⩒O2max (p < 0.001, d = 1.2859), and MAS (p = 0.047, d = 0.6139) values differed significantly across evaluation periods. Lower limb LM-adjusted ⩒O2max (p = 0.083, d = -0.0418), %⩒O2max at VT (p = 0.541, d = -0.1746), speed at VT (p = 0.337, d = -0.2774), % ⩒O2max at RCP (p = 0.776, d = 0.0806), and speed at RCP (p = 0.436, d = 0.2234) showed no difference.

Conclusion

The sensitivities of ⩒O2max adjusted for body mass and ⩒O2max adjusted for LM to detect changes in physical training state differ. Furthermore, decreases in physical fitness level, as evaluated by ⩒O2max values, are not accompanied by changes in VT.