The goal of this clinical trial is to assess the effectiveness of FES cycling in terms of changes morpho-functional characteristics of the leg muscles, training performance and bone trophism in 5 subjects with Spinal Cord Injury after 6 months of training. The main question[s] it aims to answer are:

• Do the morpho-functional characteristics of the leg muscles improve after 3 and 6 months of training with FES cycling? If any, the morpho-functional improvements are maintained one month after the end of the training?
• Does the quality of the leg bones improve after 3 and 6 months of training with FES cycling?
• Does the training performance improve during the training with FES cycling?
• Do the data referred to the vegetative nervous system change after 3 and 6 months of training with FES cycling? If yes, the changes in the vegetative nervous system are maintained one month after the end of the training?
• Does the intestinal function change after 3 and 6 months of training with FES cycling? If yes, the changes are maintained one month after the end of the training?
• Does the level of spasticity of the lower limbs change after 3 and 6 months of training with FES cycling? If yes, the changes are maintained one month after the end of the training?
• Does the level of pain perceived by pilots change after 3 and 6 months of training with FES cycling? If yes, the changes are maintained one month after the end of the training?
• Does the Psychological General Well-Being of the pilots change after 3 and 6 months of training with FES cycling? If yes, the changes are maintained one month after the end of the training?
• Does the pilots' motivation in carrying out a sporting activity change between T1 (3 months after starting the training) and T2(6 months after starting the training)?

Participants will train for 6 months with FES-cycling twice a week. Each session includes at most 30 minutes of stimulation.

Six months of FES-cycling trainings twice a week is performed for each pilot. Each session includes at most 30 minutes of stimulation.

At the beginning of training period, a conditioning phase is performed until the pilot reaches pedalling autonomy. This period is also used to define the stimulation parameters (minimum and maximum values of current intensity and pulse width), reference cadence and gear, specific for the ability of each pilot. Then the training period start and is performed indoor, setting the resistance of the smart trainer at 10% for all the participants. The sessions are organized as follows: a 3-minute warmup followed by four sets of 6 minutes of pedalling and a 3-minute cool down.

Inclusion Criteria:

• Age of subjects between 18 and 65 years.
• Subjects with paraplegia resulting from a SCI with both traumatic and non-traumatic origins occurred less than 5 years before the start of the study.
• Complete loss of motor function in the lower limbs (level ≤ T3, American Spinal Injury Association (ASIA) scale A or B)
• Adequate control of the trunk and sufficient muscle contraction using FES with surface electrodes.
• Preference for subjects with an aptitude for sports practice.
• Absence of a level of spasticity preventing device use and of disabling pain during training

Exclusion Criteria:

• Critical osteoporosis
• Skin lesions in interfaces parts with the trike,
• Dysfunction of the autonomic nervous system, and
• Psychopathological comorbidities