Does Muscle Mass Affect Running Times in Male Long-distance Master Runners?

Purpose: the aim of the present study was to investigate associations between skeletal muscle mass, body fat and training characteristics with running times in master athletes (age > 35 years) in half-marathon, marathon and ultramarathon. methods: we compared skeletal muscle mass, body fat and training characteristics in master half-marathoners (n=103), master marathoners (n=91) and master ultra-marathoners (n=155) and investigated associations between body composition and training characteristics with race times using bi- and multi-variate analyses. results: after multi-variate analysis, body fat was related to half-marathon (ß=0.9, p=0.0003), marathon (ß=2.2, p<0.0001), and ultra-marathon (ß=10.5, p<0.0001) race times. in master half-marathoners (ß=-4.3, p<0.0001) and master marathoners (ß=-11.9, p<0.0001), speed during training was related to race times. in master ultra-marathoners, however, weekly running kilometers (ß=-1.6, p<0.0001) were related to running times. conclusions: to summarize, body fat and training characteristics, not skeletal muscle mass, were associated with running times in master half-marathoners, master marathoners, and master ultra-marathoners. master half-marathoners and master marathoners rather rely on a high running speed during training whereas master ultra-marathoners rely on a high running volume during training. the common opinion that skeletal muscle mass affects running performance in master runners needs to be questioned.