Objective: The objective of this research was to develop a circuit aerobic step exercise program and to examine the effects of the circuit aerobic step exercise program on bone formation, bone resorption, muscle strength and body balance of the
postmenopausal females.
Material and Method: The samples consisted of 52 female participants from Chulalongkorn University, aged between 45-55
years old. The subjects were divided into two groups: 26 females in the circuit aerobic step exercise group (CASE) and 26
females in the control group (CON) by the simple random sampling method. The experimental group participated in the
aerobic step exercise program while wearing heart rate monitors. The exercise speed was determined by the rhythm of the music. The experimental group completed two circuits of aerobic step exercise at 6 stations, 3 times per week, for a period of 4 weeks. The intensity is 55-75% of a maximum heart rate. The control group did not participate in the circuit aerobic step exercise program. The collected data of the before and after experiment were the results of physiology test, biochemical bone
markers, muscle strength and balance ability. The collected data were compared and analyzed by the mean and standard deviation. The differences of the tests were statistically significant at the 0.05 level.
Results: After the 4-week experiment training, the circuit aerobic step exercise group had significantly decreased in resting heart rate and bone resorption (p<0.05). Muscle strength and balance on normal stability surfaces improved significantly only in the circuit aerobic step exercise group when being compared with the pretest and the control group (p<0.05).
Conclusion: The circuit aerobic step exercise had positive effect on bone formation, muscle strength and body balance. This,
therefore, is a good exercise choice for postmenopausal people and can help reduce the risks of falling especially in postmenopausal women.

Keywords: Biochemical bone marker, Bone formation, Circuit aerobic step exercise, Balance, Falling, Postmenopausal
women