Home based high intensity interval training to mitigate bone loss in post-menopausal HRT users and non-users

Ageing in females is associated with significant changes in hormone levels beginning with the onset of menopause (the cessation of menstrual cycles). Specifically, females lose their cyclical release of oestrogen, a vital regulator of bone formation, the lack of which increases the risk of declines in bone health and the onset of osteoporosis. As a result, fragility fractures tend to occur in the spine, hip and wrist, with 50 % of hip fractures leading to disability and 20% leading to death within 6 months in older women. Hormone replacement therapy (HRT) medication has been prescribed for the post-menopausal female to off-set this reduction of bone health by introducing synthetic hormones to counteract losses that occur through menopause. There are currently ~1 million HRT users in the UK, and although it may protect the bone from initial losses of menopause, it does not provide longer term protection after the medication has stopped and fractures often still occur. 

Within elderly populations, exercise interventions have demonstrated a number of advantages, but very few have shown longer term increases in physical activity levels, thus any initial health benefits are temporary. High intensity interval training has been successfully applied as a means to overcome this issue by reducing the time commitment required to carry out the exercise and has demonstrated cardio-metabolic benefits for elderly populations. For post-menopausal females, reduction in physical activity levels further heightens risk for falling and bone fractures. Future exercise regimes and interventions should look to accommodate at home workouts that can be completed to the appropriate level of intensity within the home environment. 

There is a distinct lack of data available on the impact of home-based, high intensity interval training on bone metabolism in post-menopausal females, nor have any exercise intervention studies identified differences in adaptability between HRT users and non-users. Herein, the proposed PhD project will explore the bone-specific response to a 12-week bodyweight home-based HIIT intervention in women. The project will be conducted in young, peri and post-menopausal (with and without HRT) women. Gold standard imaging measures of bone health will be utilised as well as quantification of acute adaptations via circulating bone metabolism biomarkers.