Former exercisers of an 18-month intervention display residual aBMD benefits compared with control women 3.5 years post-intervention: a follow-up of a randomized controlled high-impact trial

Exercise is recommended to enhance bone health but data on the maintenance of the exercise-induced bone benefit is sparse. The purpose of the study was to assess the maintenance of the musculoskeletal benefits obtained in an 18-month intervention of high-impact exercise in premenopausal women (34 former trainees and 31 controls). Physical performance and areal bone mineral density (aBMD, g/cm2) were measured at baseline, after 18 months, and after 5 years. All significant 18-month improvements relative to controls in the trainees' neuromuscular performance (isometric leg press, and vertical jump with and without additional 10% weight of the body mass) had been lost at the 5-year follow-up. However, since the changes in aBMD in both former trainees and controls by time were similar, the exercise-induced aBMD gain (i.e. the mean statistically significant intergroup differences of 1-3% in favor of the trainees) was maintained at the femoral neck, distal femur, patella, proximal tibia, and calcaneus at the 5-year follow-up. At lumbar spine, the difference was 1.7% at both 18-month and at the 5-year follow-ups but the difference was not statistically significant (NS) in the latter follow-up. At the trochanter and unloaded distal radius, the intergroup aBMD differences were NS at both the 18-month and 5-year follow-ups. In conclusion, the bone sites aBMD increased in response to the 18-month intervention, also demonstrated maintenance of this gain 3.5 years after the intervention. In contrast, the exercise-induced improvements in the neuromuscular performance vanished during the post intervention follow-up. These findings suggest the possibility of long-term bone benefits of high-impact training in women.