Although a multitude of factors that influence skeletal muscle blood flow have been extensively investigated, the influence of muscle length on limb blood flow has received little attention. Thus the purpose of this investigation was to determine if cyclic changes in muscle length influence resting blood flow. Nine healthy men (28 ± 4 yr of age) underwent a passive knee extension protocol during which the subjects' knee joint was passively extended and flexed through 100–180° knee joint angle at a rate of 1 cycle per 30 s. Femoral blood flow, cardiac output (CO), heart rate (HR), stroke volume (SV), and mean arterial pressure (MAP) were continuously recorded during the entire protocol. These measurements revealed that slow passive changes in knee joint angle did not have a significant influence on HR, SV, MAP, or CO; however, net femoral blood flow demonstrated a curvilinear increase with knee joint angle ( r² = 0.98) such that blood flow increased by ∼90% (125 ml/min) across the 80° range of motion. This net change in blood flow was due to a constant antegrade blood flow across knee joint angle and negative relationship between retrograde blood flow and knee joint angle ( r² = 0.98). Thus, despite the absence of central hemodynamic changes and local metabolic factors, blood flow to the leg was altered by changes in muscle length. Therefore, when designing research protocols, researchers need to be cognizant of the fact that joint angle, and ultimately muscle length, influence limb blood flow.

The reduction in physical activity following a spinal cord injury often leads to a decline in mental and physical health. Developing an exercise program that is effective and enjoyable is paramount for this population. Although functional electrical stimulation (FES) stationary cycling has been utilized in rehabilitation settings, implementing an overground cycling program for those with spinal cord injuries has greater technical challenges. Recently our laboratory team focused on training five individuals with compete spinal cord injuries utilizing an implanted pulse generator for an overground FES bike race in CYBATHLON 2016 held in Zurich, Switzerland. The advancements in muscle strength and endurance and ultimately cycling power our pilots made during this training period not only helped propel our competing pilot to win gold at the CYBATHLON 2016, but allowed our pilots to ride their bikes outside within their communities. Such a positive outcome has encouraged us to put effort into developing more widespread use of FES overground cycling as a rehabilitative tool for those with spinal cord injuries. This commentary will describe our approach to the CYBATHLON 2016 including technological advancements, bike design and the training program.

Recently our laboratory team focused on training five individuals with complete spinal cord injuries for an overground FES bike race in the 2016 Cybathlon held in Zurich Switzerland. A unique advantage team Cleveland had over other teams was the use of implanted pulse generators that provide more selective activation of muscles compared to standard surface stimulation. The advancements in muscle strength and endurance and ultimately cycling power our pilots made during this training period helped propel our competing pilot to win gold at the Cybathlon and allowed our pilots to ride their bikes outside within their communities. Such positive outcomes has encouraged us to further explore more widespread use of FES overground cycling as a rehabilitative tool for those with spinal cord injuries. This review will describes our approach to this race including information on the pilots, stimulation strategy, bike details and training program.