A randomized controlled trial of the impact of protein supplementation on leg lean mass and integrated muscle protein synthesis during inactivity and energy restriction in older persons

Abstract

Background In older persons, muscle loss is accelerated during physical inactivity and hypoenergetic states, both of which are features of hospitalization. Protein supplementation may represent a strategy to offset the loss of muscle during inactivity, and enhance recovery on resumption of activity. Objective We aimed to determine if protein supplementation, with proteins of substantially different quality, would alleviate the loss of lean mass by augmenting muscle protein synthesis (MPS) while inactive during a hypoenergetic state. Design Participants (16 men, mean ± SD age: 69 ± 3 y; 15 women, mean ± SD age: 68 ± 4 y) consumed a diet containing 1.6 g protein · kg–1 · d–1, with 55% ± 9% of protein from foods and 45% ± 9% from supplements, namely, whey protein (WP) or collagen peptides (CP): 30 g each, consumed 2 times/d. Participants were in energy balance (EB) for 1 wk, then began a period of energy restriction (ER; –500 kcal/d) for 1 wk, followed by ER with step reduction (ER + SR; <750 steps/d) for 2 wk, before a return to habitual activity in recovery (RC) for 1 wk. Results There were significant reductions in leg lean mass (LLM) from EB to ER, and from ER to ER + SR in both groups (P < 0.001) with no differences between WP and CP or when comparing the change from phase to phase. During RC, LLM increased from ER + SR, but in the WP group only. Rates of integrated muscle protein synthesis decreased during ER and ER + SR in both groups (P < 0.01), but increased during RC only in the WP group (P = 0.05). Conclusions Protein supplementation did not confer a benefit in protecting LLM, but only supplemental WP augmented LLM and muscle protein synthesis during recovery from inactivity and a hypoenergetic state. This trial was registered at http://www.clinicaltrials.gov as NCT03285737.

One Week of Step Reduction Lowers Myofibrillar Protein Synthesis Rates in Young Men

“…In this regard, an older comparator group to directly assess age-related differences in the present study would have been informative and is an important avenue for future research. (23,29,30). In the present study, daily energy intake tended (P=0.07) to decrease during SR but body weight remained stable, suggesting that participants were not in negative energy balance.…”

Nutritional Strategies to Offset Disuse-Induced Skeletal Muscle Atrophy and Anabolic Resistance in Older Adults: From Whole-Foods to Isolated Ingredients

“…The use of step-reduction (SR) in experimental research is highly relevant to numerous situations of old age in which activity levels are reduced, including transient periods of inactivity (e.g., illness and elective surgery) [23]. Previous investigations using SR typically reduce daily step-count to ≤2000/day over 7-14 days [12,15,24]. To place this in context,~750 steps/day represents typical ambulatory activity during an acute hospital stay [12,15,23].…”

“…To place this in context,~750 steps/day represents typical ambulatory activity during an acute hospital stay [12,15,23]. SR studies consistently show a reduction in postprandial [12] and free-living MPS [15,24], as well as marked reductions in muscle mass [12]. Another model of disuse atrophy, with clinical relevance, is unilateral limb immobilisation (ULI), achieved by the casting (or bracing) of a given limb over days to weeks [14,25], with the non-immobilised contralateral limb often serving as a within-subject control [26].…”

“…To date, there has only currently been one randomised controlled trial (RCT) of the influence of dietary protein during an SR model [24]. Oikawa et al (2018) found that a high quality, high-protein diet (~1.6 g•kg −1 •BW•day −1 ) during SR (~750 steps day −1 ) and a~500 Kcal energy deficit for two weeks, failed to attenuate muscle atrophy in older adults. Specifically, the provision of two daily WP drinks (providing~30 g protein each (15.4 g EAA, 4.3 g leucine) or a protein-matched hydrolysed collagen peptide drink (4.5 g EAA, 0.8 g leucine) during SR failed to attenuate the reduction (~14%) in free-living MPS [24].…”

“…An important observation from this study is that a seven-day transition from energy balance to energy restriction evoked a decline in MPS (~12%), even in the presence of double the current protein RDA (~1.6 g•kg −1 •BW•day −1 ). Alarmingly, Oikawa et al (2018) also found that, following a seven-day period of re-ambulation, MPS was not fully restored to levels pre-intervention levels, highlighting the importance for an appropriately prescribed rehabilitation and nutrition program following a period of disuse in older adults [24]. Nonetheless, whilst WP supplementation failed to prevent the loss of lean tissue during SR, WP did promote a greater recovery of lean tissue upon reambulation [24].…”