Skeletal muscle and physiologic characteristics of a world champion masters distance runner: a case study

Physiologic and skeletal muscle characteristics of a world champion and world record holder Masters distance runner were evaluated in the context of his race performances at age 50 and 51. Comparisons were made to data on other middle-aged runners and on younger, elite distance runners. The subject had a VO2 max of 62.6 mL.kg-1.min-1, an average value for elite, middle-aged runners, but a low value compared to elite, younger distance runners. The subject had a smaller proportion of ST fibers in his gastrocnemius muscle (51.9%) compared to elite distance runners (mean 70.7%) However, the subject had a higher phosphorylase activity and a succinate dehydrogenase activity that was in the same range for younger, elite distance runners. In addition, the subject's gastrocnemius muscle was characterized by small ST and FT fibers with a large capillary density, favoring oxygen diffusion. Despite a relatively modest VO2 max value, the subject has demonstrated superior performance criteria in races from 3 to 42.2 km and an apparent ability to run for several hours at a high percentage of his VO2 max. These capabilities correspond to his large muscle metabolic capacity and enhanced muscle capillarization.