Aging coincides with frequent periods of muscle disuse and, when combined with subsequent poor muscle recovery, contributes to sarcopenia, loss of muscle during aging. In order to develop effective interventions to offset deficits in muscle mass and function, Micah Drummond, PhD, and colleagues studied the cellular and molecular events that accompany muscle disuse in older adults. They found that older adults are more susceptible to losing muscle mass and strength during disuse than young persons because of reduced protein synthesis and increased protein breakdown in the muscle. To intervene during disuse periods, they implemented therapeutic tools (e.g. protein supplementation and neuromuscular electrical stimulation) that increase protein synthesis and moderate muscle breakdown. Although weakness persisted, this dual treatment was successful in maintaining muscle mass. Their research suggests that current countermeasures will need to be refined, and new pharmacological agents explored, to maintain full muscle functionality during muscle disuse in older people.
References:
Age-related differences in leg lean mass, protein synthesis and skeletal muscle markers of proteolysis after bed rest and exercise rehabilitation. Tanner, R.E., L. Brunker, J. Agergaard, K. Barrows, R. Briggs, O. Kwon, L. Young, P. Hopkins, E. Volpi, R. Marcus, P. LaStayo, M.J. Drummond. Journal of Physiology. 2015 September 15;593(18): 4259.
Neuromuscular electrical stimulation combined with protein ingestion preserves thigh muscle mass but not muscle function in healthy older adults during 5-days of bed rest. Reidy PT, McKenzie AI, Brunker P, Nelson DS, Barrows KM, Supiano M, LaStayo PC, Drummond, MJ. Rejuvenation Research. 2017 December;20(6):449.
Age-dependent skeletal muscle transcriptome response to bed rest-induced atrophy. Mahmassani ZS, Reidy PT, McKenzie AI, Stubben C, Howard MT, Drummond MJ. Journal of Applied Physiology. 2019 April 1;126(4):894.
