Lean and fat mass as determinants of muscle strength and insulin sensitivity in Chilean elderly subjects

To report the association of lean body mass with nutritional, social and economic factors and its functional consequences in free living healthy elderly subjects.

Healthy elderly subjects of low socioeconomic level were studied. Monthly income, marital status, anthropometric measures and fall risk were assessed. Mini Nutritional Assessment score was calculated. Body composition and bone mineral density were measured by double beam X ray absorptiomentry. Fasting serum lipids, fasting and postprandial insulin and glucose levels were measured. Hand grip, quadriceps and biceps strengths and maximal inspiratory and expiratory pressures were measured.

One hundred and nine subjects (56 women), aged 75 +/- 4 years old were studied. Lean body mass was 34.1 +/- 4 and 49.2 +/- 5.4 kg in women and men respectively (p < 0.001), fat mass was 22.8 +/- 7.1 and 20.7 +/- 6.4 kg in women and men respectively (p= NS). Lean body mass correlated with hand grip, quadriceps and biceps muscle strengths in men and with quadriceps and biceps strength in women. Men that exercised regularly had higher quadriceps strength and maximal expiratory pressure. Total body fat correlated positively with fasting and postprandial serum insulin levels.

In this sample, lean body mass is directly related to muscle strength mostly in men. On the other hand, total fat mass is related to serum insulin levels.