The CHILL BONES trial: testing Tai Chi and high intensity resistance and impact training (HiRIT) as therapy for older adults with low bone mass.

INTERVENTION: Arm 1: Tai Chi Participants will learn the 18 foundational movements of Shibashi style Tai Chi/Quigong. Progression will be achieved through altering the direction of exercise (incorporate multi‐directional movements) and increasing the challenge to balance through modification of base of support (foot position).. The instructor will provide participants with a selection of exercise progressions for each movement, and they will be encouraged to progress their exercises as able. Each week, participants will complete a 60‐minute community‐based Tai Chi group session, supervised by a qualified Tai Chi instructor, and an unsupervised, 30‐minute session of home‐based exercise with a standardised instructional video (delivered by the same instructor). The intervention will be performed on non‐consecutive days over a period of 8 months. A participant logbook will be completed after every session, to monitor compliance. Arm 2: HiRIT A recognised bone‐targeted program comprised of 5 sets of 5 repetitions of four exercises (jumping chin up with drop landing, back squat, overhead press, deadlift) will be completed. Resistance exercises will be progressed by gradually increasing the load over the first 2 months to achieve an intensity of 80‐85% of 1 repetition maximum (1RM) (based on individual strength). The load for each exercise will continue to increase across the remainder of the intervention period, ensuring an intensity of 80‐85% 1RM is maintained as participants adapt to the resistance exercise. The impact exercise (jumping chin up) will progress from a soft knee landing style to a stiff legged landing style, as able. Each week, participants will complete two supervised, 30‐minute sessions of HiRIT in a group setting, on the university cam CONDITION: Musculoskeletal ‐ Osteoporosis Osteoporosis;Osteopenia;Autonomic Dysfunction;Fracture; ; Osteoporosis ; Osteopenia ; Autonomic Dysfunction ; Fracture Physical Medicine / Rehabilitation ‐ Other physical medicine / rehabilitation PRIMARY OUTCOME: Total hip aBMD (g/cm2) measured by Dual‐energy X‐ray Absorptiometry (DXA) [ Baseline (pre‐intervention) and 8 months (post‐intervention).] INCLUSION CRITERIA: Community‐dwelling older adults over the age of 60 years, with low bone mass (T‐score <‐1.0 at hip or lumbar spine). Participants are otherwise healthy. They do not require a walking aid and are able to participate in an 8‐month exercise intervention, twice per week. SECONDARY OUTCOME: Appendicular skeletal muscle mass, measured using DXA[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Beat‐to‐beat blood pressure (tonic and reflexive), measured using Finapres Nova[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Beck Depression Inventory scores.[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Calf muscle density, measured using pQCT[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Calf muscle mass, measured using pQCT[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Compliance to the intervention, assessed through training diaries and monitoring across intervention period. [ Weekly for each intervention arm, across the entire intervention period (8 months).] Daily average calcium intake measured using the validated AusCal questionnaire[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Dynamic balance measured using a previously validated technique (Functional Gait Assessment).[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Fear of falling measured by a validated tool 'Falls Efficacy Scale International'.[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Functional performance measured by previously validated technique (Timed Up and Go test).[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Galvanic Skin Response (tonic and reflexive), measured using Galvanic Skin Response amplifier and finger electrodes.[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Geometric indices of bone strength, measured by pQCT[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Heart rate variability (tonic and reflexive), measured using ECG[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Historical bone‐relevant loading measured using a validated tool 'bone‐specific physical activity questionnaire (BPAQ)'[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Lower limb muscle strength, measured using five times sit to stand test (previously validated techniques).[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Lumbar spine (L1‐4) aBMD (g/cm2) measured by DXA[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Quality of life measured using the validated tool 'AQoL‐8D'.[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Skin Sympathetic Nerve Activity (SKNA) (tonic and reflexive), measured using neuECG.[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Total fat mass, measured using DXA[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Total number of falls, fracture, and musculoskeletal injuries assessed through diaries and monitoring across the intervention period.[ Weekly for each study arm, across the entire intervention period (8 months).] Upper limb muscle strength, measured using handheld dynamometer.[ Baseline (pre‐intervention) and 8 months (post‐intervention).] Volumetric indices of bone strength, measured using peripheral quantitative computed tomography (pQCT)[ Baseline (pre‐intervention) and 8 months (post‐intervention).]