Influence of aerobic training on mechanical bone strength in premenopausal women undergoing breast cancer endocrine therapy

Purpose: To assess the influence of aerobic training on bone strength in premenopausal women undergoing breast cancer endocrine therapy.

Material and methods: The study included 53 women during breast cancer treatment. Endocrine therapy consisted in using Zoladex (goserelin) 3.6 mg/28 days and Nolvadex D (tamoxifen) 20 mg/days. This was a nonrandomized, prospective clinical study. The following examinations of the assessment of bone strength in the DEXA were carried out by measuring the bone mineral density of femur, lumbar region L₁-L₄, total body and determining T-score and Z-score; the geometrical analysis of femur (hip strength analysis –HSA) using: hip axis length (HAL), hip strength index (HSI), cross-sectional moment of inertia (CSMI), cross-sectional area (CSA). The examinations were conducted for all the patients according to the schedule: before the beginning of the endocrine therapy, after 6 months and 12 months of the endocrine therapy (after 6 months’ aerobic training).

Results: After the first 6 months of the endocrine therapy without regular physical exercise, the following results were noted: the BMD (bone mineral density) mean value of the neck of femur, in the L₁-L₄ spine region and in the total body were significantly lower than the initial value. The HAL and HIS mean values did not change significantly in comparison to the pre-treatment parameters. The CSMI and CSA results were lower in comparison to their pre-treatment mean values. After 6 months’ aerobic training, in the 12 months of the follow up, the BMD mean value of the neck of femur was 1.1% (p > 0.05) lower, while in the L₁-L₄ spine region it was 5.6% (p < 0.05) lower, and in the total body 2.7% (p < 0.05) lower in comparison to the values in the sixth month of the observation. The mean value of HAL and CSA were reduced, HSI and CSMI were increased in comparison to the value in the 6th month of the observation.

Conclusions: The results obtained show that even a short course of the endocrine therapy is related to changes in the mechanical bone strength. The introduction of aerobic physical activity slows down negative changes in bones.