Part I. This study will examine the relationship between steady-state and peak exercise performance in participants with tetraplegia or paraplegia.~Participants will have their peak energy expenditure measured using a discontinuous step test. Participants will then perform three different trials of exercise at a steady state at a target intensity that corresponds with 90%, 70%, and 60% of their own measured peak energy expense. Participants will exercise at the prescribed power output until fatigue. Participants may choose which exercise mode they use (with all steady-state trials being in the same mode as the peak test), and may choose to perform the study twice in the different exercise modes. Exercise trials will be performed over a number of different sessions in a randomized order, allowing for adequate rest and recovery between trials, and depending on each participant's capabilities and preferences.~Part II. This study will determine if high intensity interval training (HIIT) results in greater energy expense than constant rate aerobic exercise, and will test if exercising with HITT effects time to fatigue.~Participants will exercise using a high intensity interval training (HIIT) protocol, which involves alternating high intensity bouts of short duration with low intensity bouts of longer duration. Participants will have their peak energy expenditure measured using a discontinuous step test. Participants will then perform one trial of steady-state exercise at a target intensity that corresponds with 50% of their peak energy expense, for a target of 20-45 minutes. Participants will perform a separate trial using a HIIT protocol of exercise at a target intensity that corresponds with 50% of their peak energy expense interspersed with bouts of high intensity (target intensity that corresponds with 90% of peak energy expense) for 30-60 seconds, for a total duration target of 20-45 minutes.~Participants may choose which exercise mode they use (with all trials being in the same mode as the peak test), and may choose to perform the study twice in the different exercise modes. Exercise trials will be performed over a number of different sessions in a randomized order, allowing for adequate rest and recovery between trials, and depending on each participant's capabilities and preferences.
To identify means to improve exercise performance in participants with tetraplegia.