A Randomised Control Trial to Assess the Efficacy of Short-term, Home-based High- Intensity Interval Training (HIT) for Improving Indices of Cardiorespiratory Fitness

Brief Summary

Detailed Description

Patients with lower peak oxygen uptake have higher mortality and morbidity when undergoing major surgery. Aerobic fitness is a potentially modifiable risk factor for postoperative complications. Traditional pre-operative exercise interventions to improve fitness involve high time and supervision-demands, often resulting in poor compliance. High-intensity interval training (HIT) is a time-efficient, feasible method to improve pre-operative fitness, however current studies only involve exercise in the laboratory setting. Study Design Thirty-six healthy volunteers aged 55y and over will be randomly allocated to one of three groups: 1) Laboratory-HIT; 2) Home-HIT; 3) No intervention. All HIT sessions will involve a brief warm-up, followed by five 1-minute bouts of high-intensity (body-weight based) exercise, interspersed with 90-seconds recovery, concluding with a brief cool-down. The primary endpoint of the study is change in VO2 peak with secondary endpoints of changes in: anaerobic threshold, insulin sensitivity and muscle mass. Subjects will be expected to perform up to a maximum of 16 HIT sessions (maximum 5 sessions per week) within a period of 31 days. Aerobic fitness will be assessed prior to and following the exercise, as will body composition, muscle structure, physical function and insulin sensitivity. For the age comparison, 24 young individuals will be recruited to either a control or home-HIT arm. In addition, the efficacy of time-matched 'static' interventions for improving cardiovascular parameters in 24 middle-aged females will also be assessed as exploratory work for these interventions. The efficacy of the static interventions in older adults at home will also be explored. Power calculation: The investigators performed a power calculation for the primary outcome of VO2 max in older adults using data from a previous study at our centre on home versus laboratory HIIT. Assuming an effect size F of 0.6 for three groups and a within group SD of 5, the alpha level was set at 0.05 and the 1-beta at 0.80. This concluded that 30 participants would be required. To allow for potential non-completion and missing data 36 older participants will be enrolled to the study (12 to each group).

Primary Outcomes

Secondary Outcomes

• Change in Anaerobic Threshold (L/min) using CPET(31 days)
• Change in resting glucose and insulin sensitivity (mmol/L)(31 days)
• Change in muscle architecture as assessed by ultrasound(31 days)
• Change in body composition (fat, muscle, bone (g)) as assessed by Dual-energy Xray Absorptiometry (DEXA)(31 days)
• Feasibility of home HIT assessed using a preset feasibility questionnaire(31 days)