title: Cardiorespiratory and Muscle Metabolic Responses During Conventional Versus Motion Sensor-Assisted Strategies for Functional Electrical Stimulation Standing After Spinal Cord Injury.
abstract: This is a case series study with the objective of comparing two motion sensor automated strategies to avert knee buckle during functional electrical stimulation (FES)-standing against a conventional hand-controlled (HC) FES approach. The research was conducted in a clinical exercise laboratory gymnasium at the University of Sydney, Australia. The automated strategies, Aut-A and Aut-B, applied fixed and variable changes of neurostimulation, respectively, in quadriceps amplitude to precisely control knee extension during standing. HC was an "on-demand" increase of stimulation amplitude to maintain stance. Finally, maximal FES amplitude (MA) was used as a control condition, whereby knee buckle was prevented by maximal isometric muscle recruitment. Four AIS-A paraplegics undertook 4 days of testing each, and each assessment day comprised three FES standing trials using the same strategy. Cardiorespiratory responses were recorded, and quadriceps muscle oxygenation was quantified using near-infrared spectroscopy. For all subjects, the longest standing times were observed during Aut-A, followed by Aut-B, and then HC and MA. The standing times of the automated strategies were superior to HC by 9-64%. Apart from a lower heart rates during standing (P = 0.034), the automation of knee extension did not promote different cardiorespiratory responses compared with HC. The standing times during MA were significantly shorter than during the automated or "on-demand" strategies (by 80-250%). In fact, the higher isometric-evoked quadriceps contraction during MA resulted in a greater oxygen demand (P < 0.0001) and wider arteriovenous oxygen extraction (P = 0.08) when compared with the other strategies. In conclusion, even though increased standing times were demonstrated using automated control of knee extension, physiological benefits compared with HC were not evident.
authors.affiliation: Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.|Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia.
authors.forename: Gustavo P
authors.initials: GP
authors.lastname: Braz
authors.affiliation: Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Russold
authors.affiliation: Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.|Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia.
authors.forename: Ché
authors.initials: C
authors.lastname: Fornusek
authors.affiliation: Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.|Biomedical Engineering Department, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Nur Azah
authors.initials: NA
authors.lastname: Hamzaid
authors.affiliation: Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Smith
authors.affiliation: Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.|Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia.|Biomedical Engineering Department, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Glen M
authors.initials: GM
authors.lastname: Davis
mesh_terms: D004599:Electric Stimulation Therapy / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D009038:Motion; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D012132:Respiratory Muscles / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000628:therapy*
keywords: Exercise physiology; Functional electrical stimulation; Muscle metabolism; Spinal cord injury; Standing