N‐Terminal Propeptide of Type III Procollagen (P3NP) Responses to Resistance Exercise in Older Adults

Abstract

Circulating P3NP, a peptide fragment cleaved from type 3 procollagen during collagen synthesis, is lower in older adults than younger adults and is predictive of changes in lean muscle mass. The purpose of this investigation was to determine whether circulating P3NP changes in response to resistance exercise training and if potential changes correspond to changes in muscle strength or quality (MQ). Twenty‐one older adults (69.4±5.2 y; BMI =28.1±5.4 kg·m−2) completed a 6‐week resistance training program in a randomized, controlled design. Resting circulating plasma P3NP, lean muscle mass, cross sectional area of the rectus femoris, muscle strength, and muscle quality were determined at baseline and after the intervention or control period by ELISA, DXA, ultrasound, leg extension 1‐RM prediction, and relative strength, respectively. P3NP changes were evaluated with repeated measures ANOVA and relationships between variables were evaluated with bivariate correlations. Short term resistance training did not result in uniform changes in circulating P3NP. Interestingly, baseline P3NP (mean ± SD = 4.91 ± 2.5 ng·mL−1) correlated to lean body mass (r=.471, p=.031) and muscle cross‐sectional changes (r=.527, p=.014), but not changes in strength or muscle quality. While further research is needed, P3NP appears to be reflective of muscle mass but not muscle quality.This research was supported from by grants from the Learning Institute for Elders (LIFE) and the Toni Jennings Exceptional Education Institute.