Muscle mass of competitive male athletes

The recent publication of the first validated equation for the estimation of muscle mass (MM) in men has made possible a comparison of MM in athletes from different sports. Limb girths and skinfold thicknesses were measured in 62 male athletes (aged 17–38 years) and 13 non‐athletic males (aged 22–36 years). The MM (g) was calculated from the equation MM = S(0.0553 Gt 2+0.0987 Gf 2+0.0331 Gc 2)‐2445, where S is stature, Gt is the mid‐thigh girth corrected for the front thigh skinfold thickness, Gc is the maximum calf girth corrected for the calf skinfold thickness and Gf is the uncorrected maximum forearm girth (all in cm). The athletes were classified as gymnasts (n = 10), basketball players (n = 10), body‐builders (n= 10), track and field power athletes (n=12), track and field long sprinters (n= 10) or distance runners (n= 10). The MM means ranged from 38.4 kg for the distance runners to 58.7 kg for the body‐builders. Both body‐builders and basketball players had significantly greater MM than gymnasts, long sprinters, non‐athletic males and distance runners (P<0.01). Also, MM was greater in track and field power athletes than in distance runners (P<0.05). The MM as a percentage of body mass (%MM) ranged from 56.5% in the non‐athletic group to 65.1% in the body‐builders; body‐builders scored higher than basketball players (P<0.05), distance runners (P<0.01) and the non‐athletic group (P<0.01). The non‐athletic men had a lower %MM than basketball players (P<0.05), long sprinters (P<0.05) and power athletes (P<0.01). Controlling for body mass by analysis of covariance altered the ranking of the group means such that the long sprinters had the greatest adjusted muscle mass, followed by the body‐builders and power athletes, with the non‐athletes showing the least. Statistically significant differences remained only between the adjusted means for the non‐athletes and all the other groups : basketball players (P < 0.01), gymnasts (P<0.001), distance runners (P<0.05), power athletes (P<0.0001), body‐builders (P<0.0001) and long sprinters (P<0.0005). These muscularity rankings in the male athletes make biological sense given the body types and functional demands of the various sports. The equation applied here appears to provide the best estimate of skeletal muscle mass to date, in that (1) it is the only cadaver‐validated equation, (2) it gives values that are consistent with all known dissection data and (3) it gives appropriate results when applied to young men with a wide range of muscularity.