This study aims to determine whether body weight-supported treadmill training (BWSTT) has beneficial effects, over and above arm-cycle ergometry training (ACET) on indicators of cardiovascular disease (CVD) risk in individuals with severe spinal cord injury (SCI).

After SCI, the primary cause of illness and death is CVD. Currently, preventative measures focus around increasing physical activity- especially through the use of ACET. However, ACET's capacity to improve cardiovascular health is questionable. Research has demonstrated that BWSTT, an alternative form of exercise, may be capable of improving cardiovascular health in individuals with SCI.

The studies primary outcome measure is carotid-to-femoral pulse wave velocity (cfPWV) which has been shown to have prognostic value for CVD above and beyond that of other risk factors. It is hypothesised that through large muscle mass involvement and postural challenge, the physical stimuli of BWSTT will reduce cfPWV and lower CVD risk in individuals with SCI.

1. Purpose To determine whether body weight-supported treadmill training (BWSTT) has beneficial effects, over and above arm-cycle ergometry training (ACET), on arterial stiffness (carotid-to-femoral pulse wave velocity, cfPWV) and secondary health outcomes (cardiovascular, autonomic and metabolic indices, fitness, body composition, and quality of life) in individuals with chronic (≥ 1 year post-injury) motor-complete cervical and high-thoracic SCI.
2. Hypothesis Through large muscle mass involvement and postural challenge, the physical and metabolic stimuli of BWSTT will reduce carotid-to-femoral pulse wave velocity (cfPWV) by 1 m/s in individuals with established risk (i.e. cfPWV ≥ norm median value of age-matched able-bodied individuals).
3. Justification for the study Cardiovascular disease (CVD) is a leading cause of morbidity and mortality in the SCI population. It is most commonly attributed to decreased physical activity levels; therefore strategies for decreasing CVD risk are centred on increasing physical activity. Unfortunately, the exercise-training literature in populations with SCI is limited, making it difficult to design evidence-based exercise prescriptions. ACET is widely used by individuals with SCI, but there is limited evidence on its ability to improve cardiovascular health. Given the evidence linking cardiovascular measures, specifically cfPWV, and CVD risk, an exercise prescription, which is capable of eliciting both acute cardiovascular responses and chronic cardiovascular adaptations, is crucial. BWSTT has demonstrated favorable cardiovascular adaptations, but is primarily employed in individuals with incomplete SCI due to the nature of the exercise. While preliminary evidence in individuals with complete SCI suggest it may have favorable training effects, its effectiveness in a large sample of individuals with chronic, motor-complete, severe SCI has yet to be established.
4. Objectives Cardiovascular adaptations in individuals with SCI predispose them to complex secondary health problems. This study will use a comprehensive assessment of cardiovascular risk factors and two different exercise interventions to assist in developing cardiovascular risk profiles and determining if BWSTT has greater efficacy than traditional exercise interventions (ACET) for decreasing cardiovascular risk in individuals with high, severe SCI.
5. Research Method This study will employ a prospective, multi-centre, randomized, controlled, single-blinded clinical trial. A total of 60 participants (20 per site) between 18-60 years of age who have sustained a motor-complete (i.e., C4-T6, AIS A or B) traumatic SCI ≥ 1 year prior will be recruited. Only individuals with cfPWV ≥ norm median value of age-matched able-bodied individuals will be eligible to participate. The primary outcome measure (cfPWV), and secondary cardiovascular and autonomic parameters will be assessed using a combination of electrocardiography, ultrasound, blood pressure, and applanation tonometry techniques. Fitness will be determined using a peak oxygen consumption test on a arm-cycle ergometer. Body composition will be determined using a dual energy x-ray absorbitrometry (DXA) scan. Metabolic indices will be determined from blood sampling. Lastly, quality of life and physical activity levels will be assessed using questionnaires. Measurements will take place at baseline (via participation in Study 1), and 3 and 6-months of exercise training. Training will involve 3, 30 - 60 minute exercise sessions per week, for 24 weeks. Both BWSTT and ACET sessions will take place at the Blusson Spinal Cord Centre at International Collaboration On Repair Discoveries (ICORD).

Inclusion Criteria:

• 18-60 years of age

• Motor-complete SCI (AIS A or B)

• Severe SCI (C4-T6)

• Individuals must be competent to give informed consent.

• cfPWV above median for age:

  1. < 30 years = 6.1 m/s
  2. 30-39 years = 6.4 m/s
  3. 40-49 years = 6.9 m/s
  4. 50-59 years = 8.1 m/s
  5. ≥ 60 years = 9.7 m/s

Exclusion Criteria:

• History and/or symptoms of CVD or cardiopulmonary problems/disease.
• Major trauma or surgery within the last 6 months.
• Active Stage 3 or 4 pressure ulcer (based on the National Pressure Ulcer Advisory Panel classification)
• Recent (within 1 year) history of lower-extremity or non-union fracture
• Any unstable medical/psychiatric condition or substance abuse disorder that is likely to affect their ability to complete this study.
• Individuals with active medical issues such as pressure sores, urinary tract infections, hypertension, or heart disorders.
• Any cognitive dysfunction or language barrier that would prevent subjects from following English instructions.
• Subjects may be excluded at the discretion of the principal investigator due to other, unforeseen, safety issues.
• Weighing >135 kg (absolute weight capacity of the body weight-supported treadmill).