Impact of Resistance Training on Bone During 40% Caloric Restriction in Growing Female Rats

Area of Science:

• Bone physiology and metabolism
• Exercise science and sports medicine
• Nutritional science and public health

Background:

• Severe caloric restriction (CR) is increasingly prevalent among normal-weight young females, posing a risk to bone health.
• Understanding the impact of CR on bone development and the potential mitigating effects of exercise is crucial.

Purpose of the Study:

• To investigate whether resistance training (RT) can preserve bone health in growing female rats subjected to a severe 40% CR diet for six weeks.
• To assess the effects of RT on bone mineral density (BMD) and bone mechanical properties under caloric restriction.

Main Methods:

• A six-week study involving 24 female rats divided into three groups: normal diet (N), sedentary 40% CR diet (D), and RT 40% CR diet (DT).
• The DT group performed ladder climbing with weights three days per week.
• Tibial BMD was measured using dual-energy X-ray absorptiometry, and bone mechanical properties were evaluated.

Main Results:

• Caloric restriction significantly reduced body mass in both D and DT groups compared to the N group.
• Sedentary rats on the CR diet (D) showed a significant 7.9% decline in tibial BMD compared to the normal diet group (N).
• Rats in the RT group (DT) experienced only a non-significant 3.3% decline in tibial BMD compared to N, and their bone mechanical properties were superior to the D group.

Conclusions:

• Resistance training demonstrated a potential to maintain tibial bone mineral density and improve bone mechanical properties in growing female rats fed a severe 40% caloric-restricted diet.
• These findings suggest that resistance exercise may be a viable strategy to counteract the negative effects of severe caloric restriction on bone health in young, growing individuals.