Metabolic Demand and Muscle Activation during Different Forms of Bodyweight Supported Locomotion in Men with Incomplete SCI

Abstract

Body weight supported locomotor training uses neuroplasticity principles to improve recovery following a spinal cord injury (SCI). Steady state locomotion using the same body weight support (BWS) percent was compared in 7 males (42.6 ± 4.29 years) with incomplete SCI and matched (gender, age) noninjured controls (42.7 ± 5.4 years) using the Lokomat, Manual Treadmill, and ZeroG. The VO2000, Polar Heart Rate (HR) Monitor, and lower limb electromyography (EMG) electrodes were worn during the 2-minute sessions. Oxygen uptake (VO2) and HR were expressed as percentage of peak values obtained using progressive arm ergometry; VO2 was also expressed relative to resting metabolic equivalents (METS). Filtered EMG signals from tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF), and medial gastrocnemius (MG) were normalized to ZeroG stepping. The Lokomat required 30% of VO2 peak (2METS) compared to ~54% (3METS) for Manual Treadmill and ZeroG sessions. HR was 67% of peak during Lokomat sessions compared to ~83% for Manual Treadmill and ZeroG. Muscle activation was higher in treadmill conditions compared to the ZeroG primarily due to increased BF activity. At the same level of BWS, locomotion using the Manual Treadmill or the ZeroG is more aerobically demanding than the Lokomat. Treadmill modalities encourage greater hip extensor activation compared to overground locomotion.

Acute Cardiorespiratory and Metabolic Responses During Exoskeleton-Assisted Walking Overground Among Persons with Chronic Spinal Cord Injury

“…This evidence suggests that exoskeleton devices requiring more active involvement in body weight support, postural control, and step initiation may elicit a greater cardiorespiratory training effect than a more passive device. In fact, when comparing the cardiorespiratory demands of exoskeletonassisted treadmill training 31 to exoskeletonassisted walking overground, participants in the present study, when walking at faster speeds, demonstrated twice the cardiorespiratory response to that of treadmill walking ( Table 4). This observation provides valuable insight as to the potential cardiorespiratory benefits associated with exoskeleton-assisted walking overground for persons with motorcomplete SCI.…”

“…However, reports of metabolic cost of exoskeleton-assisted treadmill training provide comparisons to our findings. One study reported the metabolic cost of exoskeleton-assisted treadmill walking in METs, 31 3 reported metabolic cost relative to V . O 2 , 30,32,44 and one reported metabolic cost based on metabolic power calculations.…”

“…28,29 Studies have begun to explore the cardiorespiratory and metabolic demands of exoskeleton-assisted treadmill walking and its effect on health outcomes following SCI. [30][31][32][33] Recent advances in robotic exoskeleton technology have produced a variety of devices that allow persons with SCI to walk overground. Our team was interested in exploring the potential for these devices to elicit the cardiorespiratory and metabolic responses needed to mitigate the long-term comorbidities often associated with persons with chronic motorcomplete SCI.…”

Robotically assisted treadmill exercise training for improving peak fitness in chronic motor incomplete spinal cord injury: A randomized controlled trial

“…Peak VO 2 in SCI using other modalities ZeroG® walking, 22 and manual treadmill walking. 22 A possible explanation for these differences was highlighted in an earlier study by Israel et al 17 In their investigation, the authors used both passive and active approaches during robotic stepping and compared these results with values obtained during therapist assisted treadmill stepping.…”

“…22 A possible explanation for these differences was highlighted in an earlier study by Israel et al 17 In their investigation, the authors used both passive and active approaches during robotic stepping and compared these results with values obtained during therapist assisted treadmill stepping. The passive robotic condition resulted in lower peak VO 2 responses compared to values observed during the therapist assisted walking.…”