Influence of resistance exercise on lumbar strength in older, overweight adults.

Objective: To measure lumbar extensor strength in overweight (OVW) and nonoverweight (NOVW) elderly adults before and after resistance exercise training (RX).

Design: Descriptive, comparative study.

Setting: University-based wellness center and research facility.

Participants: Eighty-four adults (age range, 60-83 y) were placed into 1 of 2 groups based on body mass index (BMI): control (NOVW; mean BMI, 22.5 kg/m(2)) or OVW (mean BMI, 29.2 kg/m(2)). Subjects were then randomly assigned to either a resistance exercise (RX) or nonexercising group.

Intervention: Six months of total body RX and isolated lumbar extension exercise.

Main Outcome Measures: Body composition, isometric lumbar extension strength, and 1-repetition maximum for each of the training exercises.

Results: Upper-body strength increased by 18.3% and 17.2% for the NOVW-RX and OVW-RX groups, respectively. Lower-body strength increased by 12.7% and 19.5% for the NOVW-RX and OVW-RX groups, respectively. At baseline, the OVW participants had greater total lumbar extension strength (1067 Nm vs 714 Nm) compared with the NOVW participants (P<.05). When expressed per kilogram of fat-free mass, there were no differences in baseline total lumbar extension strength. After RX, lumbar extension strength increased by 58% and 34% for the NOVW-RX and OVW-RX groups, respectively (P<.05). No changes in lumbar extension, upper- or lower-body strength were noted for the nontraining groups.

Conclusions: OVW subjects were found to have greater absolute and similar relative, upper-body, lower-body, and lumbar extension strength at baseline when compared with their NOVW counterparts. Also, isolated lumbar extension exercise was effective in improving lumbar extensor strength in OVW and NOVW persons.