Osteopenia is a frequent complication of anorexia nervosa (AN). To determine whether the deficit in bone mineral changes during the course of this illness, we studied 15 adolescent patients prospectively for 12-16 months using dual photon absorptiometry of the spine and whole body. At follow-up, mean weight, height, and body mass index (BMI) had increased significantly, although 6 girls had further weight loss or minimal gain (less than 1.2 kg). Spontaneous menses occurred in 2 girls, and 3 others were given estrogen replacement. Bone mineral density of the lumbar spine did not change significantly (mean +/- SD, 0.836 +/- 0.137 vs. 0.855 +/- 0.096 g/cm2), while whole body bone mineral density increased (0.710 +/- 0.118 vs. 0.773 +/- 0.105; P less than 0.05). Despite gains in bone mineral, 8 patients had osteopenia of the spine and/or whole body. Changes in weight, height, and BMI were significant predictors of change in bone mineral density. Increased bone mass occurred with weight gain before return of menses; conversely, weight loss was associated with further decreases in bone density. In 1 patient who failed to gain weight, estrogen therapy resulted in increased spinal, but not whole body, bone mineral. We also studied a second group of 9 women who had recovered from AN during adolescence. All 9 had normal whole body bone mineral for age, but 3 had osteopenia of the lumbar spine. We conclude that osteopenia in adolescents with AN reflects bone loss, perhaps combined with decreased bone accretion. Weight rehabilitation results in increased bone mineral before the return of menses. Estrogen may have an independent effect on bone mass. The persistence of osteopenia after recovery indicates that deficits in bone mineral acquired during adolescence may not be completely reversible.

We conducted a 12-wk resistance training program in elderly women [mean age 69 +/- 1.0 (SE) yr] to determine whether increases in muscle strength are associated with changes in cross-sectional fiber area of the vastus lateralis muscle. Twenty-seven healthy women were randomly assigned to either a control or exercise group. The program was satisfactorily completed and adequate biopsy material obtained from 6 controls and 13 exercisers. After initial testing of baseline maximal strength, exercisers began a training regimen consisting of seven exercises that stressed primary muscle groups of the lower extremities. No active intervention was prescribed for the controls. Increases in muscle strength of the exercising subjects were significant compared with baseline values (28-115%) in all muscle groups. No significant strength changes were observed in the controls. Cross-sectional area of type II muscle fibers significantly increased in the exercisers (20.1 +/- 6.8%, P = 0.02) compared with baseline. In contrast, no significant change in type II fiber area was observed in the controls. No significant changes in type I fiber area were found in either group. We conclude that a program of resistance exercise can be safely carried out by elderly women, such a program significantly increases muscle strength, and such gains are due, at least in part, to muscle hypertrophy.

The effects of 52 weeks resistance training at one of two exercise intensities on thigh muscle strength, fiber cross-sectional area (CSA), and tissue composition were studied in healthy 65-79-year-old women. Subjects were assigned to either a control (CO), high-intensity (HI) or low-intensity (LO) training group. Exercise regimens consisted of three sets of leg press, knee extension, and knee flexion exercises, 3 days/week, at either 80% of one-repetition maximum (1-RM) for seven repetitions (HI) or 40% of 1-RM for 14 repetitions (LO). Dynamic muscle strength was evaluated by 1-RM, thigh lean tissue mass (LTM), fat mass, and bone mineral density (BMD, g/cm2) by dual energy X-ray absorptiometry, and fiber CSA of vastus lateralis m. by histomorphometry. Muscle strength increased, on average (+/- SEM), by 59.4 +/- 7.9% and 41.5 +/- 7.9% for HI and LO, respectively, compared to 1.3 +/- 4.8% in CO (P = 0.0001). Type I fiber CSA increased over time (P < 0.05) in both exercise groups, with a trend for increased type II area (HI, P = 0.06; LO, P = 0.11). There was no significant effect of either exercise program on thigh tissue composition, except for BMD at the 1/3 site (middle third of the femur), where LO and CO groups experienced a decline (P < 0.05) of -2.2 +/- 0.5% and -1.8 +/- 0.6%, respectively, while HI maintained BMD (+1.0 +/- 1.0%). Both training programs produced significant gains in thigh muscle strength, which were associated with fiber hypertrophy, although these did not translate into appreciable alterations in thigh tissue composition.

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