Skeletal muscle ceramides and relationship with insulin sensitivity after 2 weeks of simulated sedentary behaviour and recovery in healthy older adults

Abstract

Key point Insulin sensitivity (as determined by a hyperinsulinemic‐euglycemic clamp) decreased 15% after reduced activity but surprisingly rebounded above Pre by 14% after the recovery period despite not fully returning to baseline physical activity levels. Changes in insulin sensitivity in response to reduced activity were primarily driven by men but not women. There were modest changes in ceramides (nuclear/myofibrillar fraction and serum) following reduced activity and recovery but in the absence of major changes to body composition (ie, fat mass) ceramides were not related to changes in inactivity‐induced insulin sensitivity in healthy older adults. Abstract Older adults are at risk of being physical inactivity as they encounter debilitating life events. It is unknown how insulin sensitivity is affected by modest short‐term physical inactivity and recovery in healthy older adults, and if insulin sensitivity is related to changes in serum and muscle ceramide content. Healthy older adults (64‐82y,5F/7M) were assessed before (PRE), after 2‐weeks reduced physical activity (RA) and following 2‐weeks recovery (REC). Insulin sensitivity (hyperinsulinemic‐euglycemic clamp), lean mass, muscle function, skeletal muscle sub‐fraction, fiber‐specific, and serum ceramide content and indices of skeletal muscle inflammation were assessed. Insulin sensitivity decreased 15 ± 6% at RA (driven by men) but rebounded above PRE by 14 ± 5% at REC. Mid‐plantar flexor muscle area and leg strength decreased with RA, but only muscle size returned to baseline levels following REC. Body fat did not change and only minimal changes in muscle inflammation were noted across the intervention. Serum and intramuscular ceramides (nuclear/myofibrillar fraction) were modestly increased at RA and REC. However, ceramides were not related to changes in inactivity‐induced insulin sensitivity in healthy older adults. Short‐term inactivity induced insulin resistance in older adults in the absence of significant changes in body composition (i.e., fat mass) are not related to changes in ceramides. This article is protected by copyright. All rights reserved