Does lower-leg hot-water immersion before or after exercise improve pain during and after exercise for people with osteoarthritis?

All participants will complete 3 water immersion (40ºC) sessions and a control session (in a randomised order): 1) 15-min pre-exercise lower leg immersion + 30-min exercise; 2) 30-min exercise + 15-min post-exercise lower leg immersion; 3) 15-min pre-exercise lower leg immersion + 30-min exercise + 15-min post-exercise lower leg immersion; 4) 30-min exercise only (control) There will be a 7-day washout between exposures. 1. 15-min pre-exercise lower leg immersion + 30-min exercise Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin). Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the primary investigator (PI) or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher. Exposure: Participants will complete a single 15-min hot water immersion session in 40 °C water followed by 30-min moderate intensity walk on a treadmill or cycle (intensity assessed via Borg RPE scale), followed by 15-min seated rest (no water immersion). Participants will be seated upright with water approximately below knee level. Duration: 60 min. 2. 30-min exercise + 15-min post-exercise lower leg immersion Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin). Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the primary investigator (PI) or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher. Exposure: Participants will complete 15-min seated rest (no water immersion), followed by a single 30-min moderate intensity walk on a treadmill or cycle (intensity assessed via Borg RPE scale), followed by a single 15-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately below knee level. Duration: 60 min. 3. 15-min pre-exercise lower leg immersion + 30-min exercise + 15-min post-exercise lower leg immersion Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin). Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the primary investigator (PI) or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher. Exposure: Participants will complete a single 15-min hot water immersion session in 40ºC water, followed by 30-min moderate intensity walk on a treadmill or cycle (intensity assessed via Borg RPE scale), followed by a single 15-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately below knee level. Duration: 60 min Adherence will be assessed via direct observation.