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

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 campus. These sessions will be performed on non-consecutive days, supervised by a trained physiotherapist for a period of 8 months. A participant logbook will be completed after every session, to monitor compliance and progression. Arm 3: Combined Tai Chi + HiRIT As this is a combined intervention, participants will undertake all components of Arm 1 and Arm 2 (Tai Chi and HiRIT) for the 8-month intervention period. Participants will complete HiRIT (30 mins) followed by supervised community-based Tai Chi (60 mins) once per week. They will also complete a second HiRIT session (30 mins) followed by an unsupervised home-based Tai Chi session (30 mins) performed with the same instructional video as per Arm 1. Each intervention day will be separated by at least 24 hours. Progressions for each intervention are as per Arm 1 and Arm 2. A participant logbook will be completed after every session to monitor compliance and progression.