Title: “The association between different levels of protein intake per day and muscle strength and skeletal muscle mass depending on sex, age, and physical activity level in young and middle-aged adults”
Supervisor: Dr. Darren Warburton
Committee members: Dr. Carolyn McEwen, Dr. Mahsa Jessri
Abstract: The Recommended Dietary Allowance (RDA) for protein (i.e., 0.8 g/kg body weight/day) aims to decrease the probability of deficiency. However, higher protein intake might benefit muscle strength and skeletal muscle mass. Similarly, recommendations likely differ depending on characteristics like sex, age, and physical activity level because of their implication in physiologic processes. Therefore, this thesis proposal aims to analyze whether there is an association between different levels of protein intake per day and muscle strength and skeletal muscle mass depending on sex, age, and physical activity level. This will be a secondary cross-sectional analysis from the United States of America National Health and Nutrition Examination Survey (NHANES) utilizing the 2011-2014 cycles data. We will analyze the registries of participants aged 20 to 59, with complete data for dietary assessment, handgrip strength, appendicular lean soft tissue (ALST), accelerometer-assessed physical activity, and some covariates. Protein intake per day will be normalized for body weight and categorized into different groups (i.e., <0.8, 0.8 to 1.0, 1.0 to 1.6, >1.6 g/kg/day). Handgrip strength and ALST will be normalized for body mass index. We will analyze whether the two outcome variables differ statistically significantly among protein intake groups. These analyses will be performed for the entire sample, by sex (men, women), age group (20 to 39 y, 40 to 59 y), physical activity level (low, moderate, high), and the combination of these three grouping variables (i.e., 12 subgroups). The results of this thesis proposal may help to determine whether the recommendations for protein intake per day should be adjusted for sex, age, and physical activity level, considering their cross-sectional association with muscle strength and skeletal muscle mass.