Long term adaptation to electrically induced cycle training in severe spinal cord injured individuals

Abstract

Spinal cord injured (SCI) individuals most often contract their injury at a young age and are deemed to a life of more or less physical inactivity. In addition to the primary implications of the SCI, severe SCI individuals are stigmatized by conditions related to their physically inactive lifestyle. It is unknown if these inactivity related conditions are potentially reversible and the aim of the present study was, therefore, to examine the e ect of exercise on SCI individuals. Ten such individuals (six with tetraplegia and four with paraplegia; age 27 ± 45 years; time since injury 3 ± 23 years) were exercise trained for 1 year using an electrically induced computerized feedback controlled cycle ergometer. They trained for up to three times a week (mean 2.3 times), 30 min on each occasion. The gluteal, hamstring and quadriceps muscles were stimulated via electrodes placed on the skin over their motor points. During the ®rst training bouts, a substantial variation in performance was seen between the subjects. A majority of them were capable of performing 30 min of exercise in the ®rst bout; however, two individuals were only able to perform a few minutes of exercise. After training for 1 year all of the subjects were able to perform 30 min of continuous training and the work output had increased from 4+1 (mean+SE) to 17+2 Kilo Joules per training bout (P50.05). The maximal oxygen uptake during electrically induced exercise increased from 1.20+0.08 litres per minute measured after a few weeks habituation to the exercise to 1.43+0.09 litres per minute after training for 1 year (P50.05).Magnetic resonance cross sectional images of the thigh were performed to estimate muscle mass and an increase of 12% (mean, P50.05) was seen in response to 1 year of training. In biopsies taken before exercise various degrees of atrophy were observed in the individual muscle ®bres, a phenomenon that was partially normalized in all subjects after training.The ®bre type distribution in skeletal muscles is known to shift towards type IIB ®bres (fast twitch, fast fatiguable, glycolytic ®bres) within the ®rst 2 years after the spinal cord injury. The muscle in the present investigation contained of 63% myosin heavy chain (MHC) isoform IIB, 33% MHC isoform IIA (fast twitch, fatigue resistant) and less than 5% MHC isoform I (slow twitch) before training. A shift towards more fatigue resistant contractile proteins was found after 1 year of training. The percentage of MHC isoform IIA increased to 61% of all contractile protein and a corresponding decrease to 32% was seen in the fast fatiguable MHC isoform IIB, whereas MHC isoform I only comprised 7% of the total amount of MHC. This shift was accompanied by a doubling of the enzymatic activity of citrate synthase, as an indicator of mitochondrial oxidative capacity.It is concluded that inactivity-associated changes in exercise performance capacity and skeletal muscle occurring in SCI individuals after injury are reversible, even up to over 20 years after the injury. It follows that electricall...

Glucose tolerance and physical activity level in people with spinal cord injury

“…However, from a point of speculation, it is possible that insulin resistance may be present in muscles both below and above the lesion. In paralyzed muscle, characteristic changes include a marked decrease in cross-sectional area of both slow-and fast-twitch muscle fibers 6 and reduction in slow myosin heavy chain proportion, and concomitantly, a marked shift to fast myosin heavy chain isoforms; 7 and increased intramuscular fat accumulation. 4,5 No studies have compared GLUT4 content in those with and without SCI.…”

“…7,12,17 For example, electrical stimulation-induced leg cycling training increased expression of muscle fiber types I and IIa, 7 increased GLUT4 content 12 improved glucose tolerance and insulin sensitivity 17 and increased oxidative capacity. 7,12 Interestingly, with regard to physical activity, our data showed that it was not only participation in exercise, but also in non-exercise-related activity that differed between those with normal glucose tolerance and those with disordered glycemia. Those with normal glucose tolerance engaged in more housework (median 0.7 h day -1 , range 0-6.97 h day -1 ), with participants citing specific tasks, such as doing the washing, looking after young children and vacuuming.…”

“…1,2 It has been suggested that the extent of neurological impairment after SCI is an important determinant of these impairments; participants with complete tetraplegia (TETRA) had higher levels of serum glucose and plasma insulin during a 2-h oral glucose tolerance test (OGTT) and higher incidence of IGT or diabetes than participants with either incomplete TETRA or complete or incomplete paraplegia (PARA). 3 The suggestion that greater neurological deficit is associated with poorer glucose tolerance may be explained by the consequences of denervation such as skeletal muscle atrophy 4,5 and altered fiber-type proportions, 6,7 with the volume of muscle affected related to level and completeness of the neurological lesion. Skeletal muscle is the major site for insulin-mediated glucose disposal and glucose transport is rate limiting for glucose utilization under most conditions.…”

Physiological effects of lower extremity functional electrical stimulation in early spinal cord injury: lack of efficacy to prevent bone loss

“…Electrical stimulation has a long history in the diagnosis [1][2][3] and treatment of disorders [4][5][6] of the central nervous system. The application of this physical modality in the rehabilitation of people with spinal cord injury (SCI) has been extensively studied as a 'functional therapy'.…”

“…The application of this physical modality in the rehabilitation of people with spinal cord injury (SCI) has been extensively studied as a 'functional therapy'. [4][5][6][7] Clinical and experimental studies indicate that neuromuscular electrical stimulation can both affect and effect changes in muscle fibre contractile properties 4,8 and metabolism, 9,10 as well as responses at physiological 5,6 and functional levels. Although well studied, 7,[11][12][13] there is conflicting evidence about the efficacy of electrically evoked muscle activation in the stimulation of bone metabolism (bone formation and/or reduction of bone loss), and the clinical role of functional electrical stimulation (FES) in the treatment of osteoporosis resulting from neurological damage.…”