Sarcopenic Characteristics of Active Older Adults: A Cross-sectional Exploration.

Abstract

Background: Ageing is associated with a decline in skeletal muscle mass and function (strength and power), known as sarcopenia. Inadequate dietary protein and inactivity have been shown to accelerate sarcopenia outcomes, occurring at different rates in males and females. Regardless, active older adults who often exceed the exercise guidelines still show signs of sarcopenia. This study aimed to explore the link between age, physical activity, protein intake, and biological sex with skeletal muscle mass, strength, power, and physical capacity/performance in active older adults. Methods: Fifty-four active older adults were grouped according to age (middle aged: 50-59 years, and older age: ≥60 years), exercise volume (low: <150min/week, moderate: >150-299min/week, and high: >300min/week), protein intake (low: <0.8g/kg body mass (BM), moderate: ≥0.8-1.19g/kgBM, and high: ≥1.2g/kgBM), and biological sex (males and females). Skeletal muscle and fat mass (dual x-ray absorptiometry), strength (1-repetition maximum using leg press, chest press, lateral pull down, and hand grip), power (counter movement jump), and general fitness (cardiorespiratory capacity and gait speed) were assessed. Data were grouped based on variables, and a one-way ANOVA (or non-parametric equivalent) was applied to assess group differences. Results: The middle-aged group had a 13%, 17%, and 12% higher leg press, chest press, and lateral pull down, respectively, compared to the older aged group (P<0.05). Participants that reported moderate and high training volumes had lower body fat mass compared to those that reported lower training volumes (26.1%, 25.1%, and 35.6%, respectively; P<0.001). Similarly, higher leg press (22% and 27%) and chest press (22% and 23%) was observed with moderate and high training volumes compared with lower. Higher protein intakes were associated with significantly less body fat mass (P=0.019), higher leg strength (P=0.038) and relative power (W/kg) (P=0.048) compared to the moderate and low protein intake groups. Significant differences based on biological sex were observed for all outcomes expect for gait speed (P=0.611) and cardiorespiratory fitness (P=0.147).Conclusion: Contributions of age, physical activity, daily protein intake, and biological sex can explain the individual variation in outcomes related to changes in body composition, strength, power, and/or cardiorespiratory fitness in a cohort of active older adults.