20% Caloric Restriction did not Impact Bone Health nor Exercise-Induced Elevations in Bone Mass in Young Female Rats

Area of Science:

• Bone physiology
• Nutritional science
• Exercise physiology

Background:

• Bone health is crucial during growth periods.
• Caloric restriction (CR) and resistance training are known to influence bone metabolism.
• The combined effects of CR and resistance training on bone health in young, growing animals require further investigation.

Purpose of the Study:

• To investigate the impact of a 20% CR diet, with and without resistance training, on tibial bone mineral density (BMD) in growing young female rats.
• To determine if CR alters the bone-protective effects of resistance training during development.

Main Methods:

• Forty female rats (5 weeks old) were divided into five groups: baseline, sedentary normal diet, sedentary 20% CR diet, resistance-trained normal diet, and resistance-trained 20% CR diet.
• Resistance training involved climbing a vertical ladder with weights 3 days/week for 6 weeks.
• Tibial BMD was measured using dual-energy x-ray absorptiometry (DXA).

Main Results:

• Caloric restriction significantly reduced body mass in both sedentary and resistance-trained groups compared to normal diet groups.
• Tibial BMD was not significantly different between sedentary rats on a normal diet and those on a 20% CR diet.
• Resistance training led to a significant elevation in tibial BMD compared to sedentary groups, irrespective of diet.

Conclusions:

• A 20% CR diet for 6 weeks during the growth period does not negatively impact tibial BMD in young female rats.
• Resistance training effectively enhances BMD in growing female rats.
• Caloric restriction does not interfere with the positive effects of resistance training on bone mineral density during growth.