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 trainingcharacteristics 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 ( =0.9, P=0.0003), marathon ( =2.2, P<0.0001), and ultra-marathon ( =10.5, P<0.0001) race times. In master half-marathoners ( =-4.3, P<0.0001) and master marathoners ( =-11.9, P<0.0001), speed during training was related to race times. In master ultra-marathoners, however, weekly running kilometers( =-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.