Hypoestrogenism causes an imbalance in bone homeostasis, which can affect bone microarchitecture and result in loss of tissue strength and increased risk of fractures. Physical training and melatonin can act on bone formation; however, in a state of hypoestrogenism, the potential effect of the combination of both interventions is not understood. The aim of this study was to investigate the effect of 12 weeks of swimming physical training associated with melatonin administration on the mineral content and biomechanical parameters in bone tissue under hypoestrogenism conditions. The animals (Wistar rats) performed an incremental swimming test to determine the individual anaerobic lactacidemic threshold and underwent bilateral ovariectomy. The interventions consisted of physical training (30 min, 5 d/wk, 90% of individual anaerobic lactacidemic threshold) and melatonin administration (10 mg/kg/d via gavage). After 12 weeks, the femur was collected for the analysis of calcium and phosphorus contents and the three-point flexion test to obtain biomechanical parameters. Data were expressed as mean±standard deviation, subjected to factorial analysis of variance and the Newman–Keuls post hoc test (a significance level of 5%). The association of endurance physical training with melatonin administration resulted in a significant increase in calcium and phosphorus contents, while presenting a significant increase in the capacity to support a greater maximum load and promote rigidity to bone tissue. Considering the detrimental impact of hypoestrogenism on bone tissue, both interventions, endurance physical training and melatonin administration, were able to generate beneficial results regarding the bone mineral content, influencing the improvement of biomechanical parameters that determine tissue strength, which can prevent bone fracture.

Received: 09 March 2026

Accepted after revision: 09 April 2026

Article published online:
23 April 2026

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