The study compares effects of 4-week walking training program on a walking track with difference surface [WTDS] and a firm ground on functional ability of ambulatory individuals with incomplete spinal cord injury [iSCI], using within- and between-group comparisons.

Inclusion Criteria:

1. Age at least 18 years
2. Having an incomplete SCI (the American Spinal Cord Injury Association (ASIA) Impairment Scale or AIS C or D) (Kirshblum et al., 2011)
3. At a sub-acute or chronic stage of injury (post injury time: PIT > 3 months) (Wirth et al., 2008; Blackwell et al., 2001)
4. Able to walk with or without a walking device for at least 10m (Behrman et al., 2005; Lam et al., 2008; Jackson et al., 2008)
5. Having a body mass index (BMI) between 18.5-29.9 kg/m2 (Woo et al., 2007)

Exclusion Criteria:

1. Having an SCI from a progressive disease such as multiple sclerosis or malignancy
2. Having other medical conditions that might affect ambulatory ability, such as pain in the musculoskeletal system with an intensity of pain more than 5 out of 10 on a numeric rating pain scale (Dijkers, 2010), deformities of the spine and lower extremities (i.e. scoliosis, kyphosis, and equinovarus) and other neurological or other medical disorders (thromboembolism, autonomic dysreflexia).
3. Severe spasticity of the lower extremities (Modified Ashworth Scale (MAS) more than 2) (Bohannon & Smith, 1987; Scivoletto et al., 2008).