BACKGROUND: Physical inactivity impairs insulin sensitivity, which is exacerbated with aging. We examined the impact of 2 wk of acute inactivity and recovery on glycemic control, and integrated rates of muscle protein synthesis in older men and women.
METHODS: Twenty-two overweight, prediabetic older adults (12 men, 10 women, 69 ± 4 y) undertook 7 d of habitual activity (baseline; BL), step reduction (SR; <1,000 steps.d-1 for 14 d), followed by 14 d of recovery (RC). An oral glucose tolerance test was used to assess glycemic control and deuterated water ingestion to measure integrated rates of muscle protein synthesis.
RESULTS: Daily step count was reduced (all p < .05) from BL at SR (7362 ± 3294 to 991 ± 97) and returned to BL levels at RC (7117 ± 3819). Homeostasis model assessment-insulin resistance increased from BL to SR and Matsuda insulin sensitivity index decreased and did not return to BL in RC. Glucose and insulin area under the curve were elevated from BL to SR and did not recover in RC. Integrated muscle protein synthesis was reduced during SR and did not return to BL in RC.
CONCLUSIONS: Our findings demonstrate that 2 wk of SR leads to lowered rates of muscle protein synthesis and a worsening of glycemic control that unlike younger adults is not recovered during return to normal activity in overweight, prediabetic elderly humans.
Briony Lago has joined the lab as part of her McMaster Chemical Biology Co-Op program. She will be working on our ‘Omic’ Responses & Inactivity in Aging project (a collaboration with colleagues in Kinesiology & Chemistry, see here) as well as our collaboration with Bates College on the role of Nfe2 in the oxidative stress response during zebrafish development (see here).
The McArthur lab is proud to collaborate with colleagues in the Faculty of Science on the metabolic and transcriptional responses to human inactivity and aging under the leadership of Dr. Stuart Phillips (pictured) of the Department of Kinesiology’s Exercise Metabolism Research Group. Dr. Phillips successfully competed in Faculty of Science Call for Interdisciplinary Projects 2015 to obtain funding for this project, which also includes Dr. Martin Gibala (Department of Kinesiology) and Dr. Philip Britz‐McKibbin of the Department of Chemistry.