Effects of High-Intensity Interval Training on Bone Health in Hong Kong Older Women

Inclusion Criteria: * • 60 to 74 years at the start date of the project * diagnosed with osteopenia by DXA scan screening with a BMD at the femoral neck or total hip or lumbar spine between -1 and -2.5 SD T-score below the average values * Passing the PAR-Q plus screening or with the physician's approval for readiness to participate in high-intensity exercise * Above the average level of 2-mins stepping showing competent aerobic fitness * No restriction on physical mobility * No cognitive impairment, as determined by the Chinese version of the Mini-Mental Status Examination (i.e., score \< 24) * No previous substantial experiences in practicing HIIT. The written informed consent form will be collected from each participant Exclusion Criteria: * • Severe chronic disease restricting high-intensity exercise * Having cognition impairment regarded by specialists * checked through medical records at HA Go app platform in the past 6 months, have concurrent medical conditions (e.g., thyrotoxicosis or hyperparathyroidism, Paget's disease, renal disease, diabetes, knee or hip osteoarthritis) and use medications (e.g., corticosteroids, estrogen, thyroxine, thiazide diuretics, or antiretroviral agents) known to affect bone metabolism during past 2 years * any condition with osteoporosis, osteoporotic fractures * current smoker * alcohol 3 or more units per day.