Effect of different combinations of breathing exercises on sitting balance, swallowing and breathing in people with a spinal cord injury

The study design is a Bayesian Optimal Phase 2 Adaptive (BOPII) Trial. The study will include seven intervention arms, each arm receives a different combination of breathing (respiratory) exercises. One intervention arm is recruited at a time, with 16 participants anticipated to be enrolled in each arm with Stage 1 analysis occurring for each arm after the first 8 participants have been enrolled and completed. This Stage 1 analysis will determine if a further 8 people are recruited into Stage 2 of the arm, ie if non-futile an additional 8 people will be recruited for that intervention arm. If Stage 1 is deemed futile, then that arm is abandoned and recruitment into the next arm will commence. The order of the arms will be in progression of respiratory muscle training combination complexity, ie commencing with a single type of exercise first, for example expiratory muscle training only, and the last arm will be the combination of all three exercises. Participants in each arm (group) will receive 15-30 minutes of daily respiratory exercise therapy for six weeks, supervised by a trained physiotherapist, exercise physiologist or research assistant with clinical health sciences experience. Respiratory exercises will be targeted at inspiratory or expiratory muscles with or without additional abdominal functional electrical stimulation, depending on the participant's group. The seven arms include different combinations of respiratory therapy as follows: 1) expiratory muscle training (EMT) alone, 2) inspiratory muscle training (IMT) alone, 3) abdominal functional electrical stimulation (aFES) alone, 4) concurrent combination of IMT + EMT, 5) concurrent combination of IMT + aFES, 6) concurrent combination of EMT + aFES, 7) concurrent combination of IMT + EMT + aFES. The inspiratory and expiratory exercises (IMT or EMT) will consist of 3-5 sets of 10 breaths through a commercially available respiratory muscle training device set initially at 30% of their maximal respiratory strength. Exercise intensity will be increased by 10% each week over the 6 weeks of training. The aim is for the participant to achieve all 5 sets, however due to fatigue some participants may only be able to achieve a minimum of 3 sets when they commence, but the therapist will attempt to increase this in a stepwise fashion to 5 sets by week 3 of the training. The abdominal functional electrical stimulation (aFES) using a commercial Neurotrac stimulator, with a trigger function, The amplitude (mA) will be set to a strong observable level of muscle contraction, a frequency of 50Hz and 200us pulse width, and will consist of 3-5 sets of 10 breaths of triggered abdominal muscle contractions timed with expiration. Intensity will be increased by 5mA each week or as tolerated by the participant. The details of each training session provided to participants will be recorded by the therapist in a training diary.