31 Physical Activity, Muscle Strength and Quantity: Preliminary Findings From the Mass_Lifecourse Cohort

Abstract

Introduction We established the MASS-Lifecourse study to investigate changesin skeletal muscle between ages 45-85. Reduced physical activity(PA) is a key factor linked to the development of sarcopenia. Ouraim was the describe the amount and patterns of PA and sedentarybehaviour (SB), and relationships with muscle strength and quantity, among MASS-Lifecourse participants. Method Participants wore a triaxial accelerometer on their dominant wristfor seven days. Recordings were analysed to calculate time inmoderate-vigorous PA (MVPA) with time not in MVPA classifiedas SB based on wrist position. Muscle strength was measured witha Jamar grip dynamometer and the 5 chair-stand test. Musclequantity was assessed using appendicular lean muscle mass fromdual-energy X-ray absorptiometry. Physical performance wasassessed by gait speed. Results 68 participants (31 male) aged 47-84 (mean 65) participated inthe present study. Median daily MVPA was 19.1 (IQR 7.1, 36.6)minutes and was lower with age. The mean sedentary time per daywas 767.1 minutes per day and increased with age. The pattern of MVPA across the day changed with age: the oldest group (75-84 years) achieved a lower morning activity peak followed by anearlier decline whilst the younger groups were more consistentlyactive throughout the day. Participants were more active thanpopulation reference data from the Active Lives Survey. Time spent in MVPA was positively associated with muscle strength and physical performance, whereas SB was negatively associated.Muscle quantity was not associated with PA or SB. Conclusions Participants in the MASS-Lifecourse study are more active thanthe general population but still show age-related declines inphysical activity and strength. Future work in the cohort aims toelucidate mechanisms underlying the age-related loss of musclestrength and quantity.