The aim of this study is to investigate two different modalities of functional electrical stimulation (FES) leg exercise in patients with spinal cord injury (SCI). The primary outcomes being compared are 1. FES-induced leg aerobic fitness, and 2. FES-induced leg strength. There will be two FES-leg training groups, and sub-acute patients with SCI will be randomised between the groups - high-short [HI-SHORT] and low-long [LO-LONG]. Both groups (n=10 per group) will exercise on the Hasomed RehaStim™ exercise ergometer for 6-8 weeks, three-four times per week (24 therapy sessions). [HI-SHORT] will perform 10 x 2-min of high-intensity interval training with a recovery of 1-2 min between exercise bouts. [LO-LONG] will perform 20+ min of continuous exercise at a low-moderate exercise intensity. Exercise intensity for [HI-SHORT] and [LO-LONG] will be titrated by neuromuscular stimulation characteristics. The primary outcomes will be assessed before training commences and after 6-8 weeks of training has been completed.

Inclusion Criteria:

• Greater than 6-weeks post-trauma after SCI.
• Traumatic and atraumatic spinal cord injuries between C7 and T10
• Participants diagnosed with "motor complete' spinal cord injury American Spinal Injury Association Impairment Scale A and B.
• Age between 18-75 years old.
• Both male and female.
• Have at least 90º bilateral knee flexion.
• Able to perform FES muscle contractions (not FES intolerant).
• Able to follow verbal instructions.

Exclusion Criteria:

• A recent history of trauma to the lower limb.
• Severe or infected pressure sore on weight-bearing skin areas.
• Illness caused by acute urinary tract infection.
• Uncontrolled spasticity or pain.
• History of cardiovascular / cardiorespiratory disease contraindicating exercise.
• Uncontrolled orthostatic hypotension.
• Unhealed decubiti at electrode placement area.
• Recurrent and uncontrolled autonomic dysreflexia.
• Active heterotopic ossification.
• Other peripheral or central neurologic injury.