The effectiveness of preoperative heat therapy and high-intensity interval training for prehabilitation in patients awaiting hip or knee arthroplasties

Participants will be randomised to either heat therapy or HIIT of the intervention groups outlined below, and perform this intervention only. If they have not been scheduled for their surgery following the 12 week intervention, all participants will completed the Home-based maintenance phase for 12 weeks or, shorter if their surgery is scheduled before this time. Heat Therapy Location: School of Physical Education, Sport and Exercise Science Aquatic Facility (University of Otago, Dunedin). Supervision: Heat sessions will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and heat and exercise session particulars (i.e., duration in spa, type of exercise performed etc.) will be recorded at each session by the supervising researcher. Exposure: Participants will complete 3 heat therapy sessions per week, with bathing duration progressively increasing from 20 to 30 min, as tolerable (20 minutes first week, 25 min second week and 30 min third and subsequent weeks). Participants will be seated (or semi-recumbent) in a heated spa (39-40 °C), with water approximately top-sternal level. Following bathing, participants will complete 20-30 min of light-intensity resistance exercise (i.e., bicep curls, chest press using therabands etc.). Participants will perform a series of whole body exercises in 1 min intervals, separated with 1 min recovery. Duration: Participants will complete 12 weeks of heat therapy. High intensity interval training (HIIT) Location: School of Physical Education, Sport and Exercise Science Clinical Exercise Facility (University of Otago, Dunedin). Supervision: HIIT sessions will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), the PI or a research assistant; all supervising researchers are first aid trained. Attendance and exercise session data (i.e., exercise heart rate) will be recorded at each session by the supervising researcher. Exposure: HIIT will be performed 3 times a week using a cross-trainer, arm ergometer and / or cycle (dependent on tolerance). Each session will begin with a 5-min warm-up on an exercise modality of the participants choosing. Initial sessions will begin with 6 x 60-s intervals, with recovery (90-120 s) in between intervals. Interval duration will remain constant throughout the intervention, with the aim of increasing the number of intervals to 8 and recovery duration decreasing to 60 sec, based on participant progress. Exercise intensity will initially be set at 85% of each participants VO2peak, before increasing each interval until a score of 7/10 on the rating of perceived exertion (RPE) scale is achieved; this corresponding workload will be used for subsequent intervals. As fitness increases, workload will increase to maintain this RPE,. Each session will last ~30 min and include a cool-down with light-intensity, whole-body flexibility exercise. Duration: Participants will complete 12 weeks of upper-limb HIIT. Home-based maintenance phase Location: At the participant’s home, preferred exercise facility or in the community. Supervision: Home-based maintenance sessions will be unsupervised. A registered CEP will design a personalised exercise programme and all participants will be educated on how to perform it safely and effectively. Participants will record a log of daily step count. Exposure: The personalised exercise programme will be based on the participant’s fitness, joint pain levels and their access to exercise equipment / facilities. The training regimen will follow ACSM recommendations for aerobic exercise in those with osteoarthritis, which recommend accumulating at least 150 minutes of activity each week. All participants will be provided an RPE scale and instructed to progress exercise intensity to a limit of 5/10 (i.e., “Hard”), and avoid excessive increases in acute joint pain. Where a participant has no access to exercise equipment / facilities, a pedometer will be provided; advice will be to steadily increase daily step count (determined from 12-week reassessment) by 10% every 4 weeks. Duration: The maintenance phase will last for 12 weeks or until one week prior to surgery (whichever is sooner).