title: Effect of training on contractile and metabolic properties of wrist extensors in spinal cord-injured individuals.
abstract: Paretic human muscle rapidly loses strength and oxidative endurance, and electrical stimulation training may partly reverse this. We evaluated the effects of two training protocols on the contractile and metabolic properties of the wrist extensor in 12 C-5/6 tetraplegic individuals. The wrist extensor muscles were stimulated for 30 min/day, 5 days/week, for 12 weeks, using either a high-resistance (Hr) or a low-resistance (Lr) protocol. Total work output was similar in both protocols. The nontrained arm was used as a control. Maximum voluntary torque increased in the Hr (P < 0.05) but not the Lr group. Electrically stimulated peak tetanic torque at 15 HZ, 30 HZ, and 50 HZ were unchanged in the Lr group and tended to increase only at 15 HZ (P < 0.1) in the Hr group. Resistance to fatigue, however, increased (P < 0.05) in both Hr (42%) and Lr (41%) groups. Muscle metabolism was evaluated by (31)P nuclear magnetic resonance spectroscopy ((31)P-NMRS) during and following a continuous 40-s 10-HZ contraction. In the Hr group the cost of contraction decreased by 38% (P < 0.05) and the half-time of phosphocreatine (PCr) recovery was shortened by 52% (P < 0.05). Thus, long-term electrically induced stimulation of the wrist extensor muscles in spinal cord injury (SCI) increases fatigue resistance independent of training pattern. However, only the Hr protocol increased muscle strength and was shown to improve muscle aerobic metabolism after training. Muscle Nerve 27: 72-80, 2003
authors.affiliation: Clinic for Para- and Tetraplegia, The Neuroscience Centre, Rigshospitalet, Copenhagen University Hospitals, Copehagen, Denmark. Hartkopp@dadlnet.dk
authors.forename: Andreas
authors.initials: A
authors.lastname: Hartkopp
authors.forename: Stephen D R
authors.initials: SD
authors.lastname: Harridge
authors.forename: Masao
authors.initials: M
authors.lastname: Mizuno
authors.forename: Aivaras
authors.initials: A
authors.lastname: Ratkevicius
authors.forename: Björn
authors.initials: B
authors.lastname: Quistorff
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
authors.forename: Fin
authors.initials: F
authors.lastname: Biering-Sörensen
mesh_terms: D000328:Adult; D004599:Electric Stimulation Therapy / Q000592:standards; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010243:Paralysis / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D010759:Phosphorus Isotopes; D010807:Physical Endurance / Q000502:physiology; D015203:Reproducibility of Results; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000628:therapy*; D014955:Wrist Joint / Q000502:physiology
chemical_list: D010759:Phosphorus Isotopes