Abstract
ObjectiveTo investigate the effects of a 16-week concurrent exercise regimen [resistance exercise (RE) + functional exercise (FE)] in combination with, or without, a leucine-enriched whey protein isolate supplement on muscle strength, physical functioning, aerobic capacity, and cardiometabolic health in older adults (≥60 years). Physical activity levels were also evaluated 6 months post-cessation of the intervention.MethodsForty-six, community-dwelling, previously untrained males, and females [age: 68 ± 5 years (mean ± SD); BMI: 27.8 ± 6.2 kg/m2] who completed the trial were initially randomized to one of two independent arms [Exercise n = 24 (E); Exercise+Protein n = 22 (EP)]. Both arms completed 16 weeks of RE (performed to fatigue) (2 times/week) with FE (1 time/week) on non-consecutive days. Additionally, EP were administered a leucine-enriched whey protein supplement (3 times/day) for 16 weeks based on individual body-weight (1.5 g/kg/day).ResultsAs a result of dietary supplementation, protein intake increased in EP (∼1.2 ± 0.4 to 1.5 ± 0.7 g/kg/day) during the intervention. Maximal strength (1RM) values for leg press (E: +39 ± 7 kg, p = 0.006; EP: +63 ± 7 kg, p < 0.001), chest press (E: +22 ± 4 kg, p < 0.001; EP: +21 ± 6 kg, p < 0.001), and bicep curl (E: +7 ± 0 kg, p = 0.002; EP: +6 ± 1 kg, p = 0.008) significantly increased in E and EP respectively, with no differences between arms (p > 0.05). Physical functioning in the obstacle course (E: -5.1 ± 6.8 s, p < 0.001; EP: -2.8 ± 0.8 s, p < 0.001) and short-physical performance battery scores (E: +0.5 ± 0.5, p = <0.001; EP: +0.4 ± 0.5, p = 0.038), and aerobic capacity in the 6-min walk test (E: +37 ± 24 m, p = 0.014; EP: +36 ± 3 m, p = 0.005) improved in E and EP respectively, with no differences between arms (p > 0.05). No significant change was observed for markers of cardiometabolic health (glycaemic control or blood pressure) (p > 0.05). At follow-up, 86% of older adults reported to performing physical activity ≥1 per week. Of those, 61% were still participating in strength- and cardiovascular- based exercise.ConclusionConcurrent exercise (RE + FE) offers a potent method to combat age-related muscle weakness, and our results suggest a high proportion of older adults may continue to exercise unsupervised. However, leucine-enriched whey protein isolate supplementation did not confer any additional benefit in those already consuming ample amounts of dietary protein at trial enrolment. Future trials should utilize a whole-foods approach and investigate the effects in frail and non-frail older adults habitually consuming the RDA of protein, to assess if a higher intake of protein is needed to delay the onset of muscle weakness.Trial RegistrationClinicaltrials.gov Identifier: NCT02912130.
Highlights
The aging epidemic has led to increased awareness of frailty phenotypes, notably muscle weakness (Fried et al, 2001), which manifests around 50 years of age, and occurs at a 2–5 times more rapid rate than muscle mass loss (Goodpaster et al, 2006)
Participants included in the final analysis were distributed in each arm and when split by gender no difference was detected (p = 0.55)
Arms did not differ in any baseline measure (p > 0.05)
Summary
The aging epidemic has led to increased awareness of frailty phenotypes, notably muscle weakness (Fried et al, 2001), which manifests around 50 years of age, and occurs at a 2–5 times more rapid rate than muscle mass loss (Goodpaster et al, 2006). Two prophylactics suggested to curtail muscle weakness are resistance exercise (RE) and dietary-protein. RE is a potent stimulus to increase muscle strength and physical functioning (Fiatarone et al, 1990; Stec et al, 2017) whilst epidemiological data show higher quantities of dietary-protein (>1 g/kg/day) can curb declines in grip strength (McLean et al, 2016) and mobility (Mustafa et al, 2018). The body of evidence to support the increased requirement of dietary-protein to augment RE effects on muscle strength is inconclusive. Disparate findings may be due to total amount, type and timing of supplemented protein, and in particular, sub-optimal intakes of the essential amino acid leucine, the key regulator of muscle anabolism (Devries et al, 2018). Acute trials utilizing isotope tracers have demonstrated an anabolic resistance in older adults, whereby higher dosages of dietary-protein rich in leucine are suggested to overcome this phenomenon (Moore et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
