Exercise‐induced overexpression of key regulatory proteins involved in glucose uptake and metabolism in tetraplegic persons: molecular mechanism for improved glucose homeostasis

Abstract

Complete spinal cord lesion leads to profound metabolic abnormalities and striking changes in muscle morphology. Here we assess the effects of electrically stimulated leg cycling (ESLC) on whole body insulin sensitivity, skeletal muscle glucose metabolism, and muscle fiber morphology in five tetraplegic subjects with complete C5-C7 lesions. Physical training (seven ESLC sessions/wk for 8 wk) increased whole body insulin-stimulated glucose uptake by 33+/-13%, concomitant with a 2.1-fold increase in insulin-stimulated (100 microU/ml) 3-O-methylglucose transport in isolated vastus lateralis muscle. Physical training led to a marked increase in protein expression of GLUT4 (378+/-85%), glycogen synthase (526+/-146%), and hexokinase II (204+/-47%) in vastus lateralis muscle, whereas phosphofructokinase expression (282+/-97%) was not significantly changed. Hexokinase II activity was significantly increased, whereas activity of phosphofructokinase, glycogen synthase, and citrate synthase was not changed after training. Muscle fiber type distribution and fiber area were markedly altered compared to able-bodied subjects before ESLC training, with no change noted in either parameter after ECSL training. In conclusion, muscle contraction improves insulin action on whole body and cellular glucose uptake in cervical cord-injured persons through a major increase in protein expression of key genes involved in the regulation of glucose metabolism. Furthermore, improvements in insulin action on glucose metabolism are independent of changes in muscle fiber type distribution.

Improved glucose tolerance and insulin sensitivity after electrical stimulation-assisted cycling in people with spinal cord injury

“…Similar to our results, Hjeltnes et al 43 recently found that ES-assisted cycling increased insulin-mediated glucose disposal by 33+13%. 43 They also reported that after 8 weeks of training, basal and insulin stimulated glucose transport activity were increased by 1.6-and 2.1-fold, respectively, compared to pretraining level. The subjects in their study completed seven exercise sessions (30 min/session) per week, more than double the frequency of training compared to the protocol we used in the present study.…”

“…The subjects in their study completed seven exercise sessions (30 min/session) per week, more than double the frequency of training compared to the protocol we used in the present study. The training Improved glucose tolerance after ES-assisted cycling JY Jeon et al frequency from the study of Hjeltnes et al 43 was rather unrealistic since many people with SCI are unable to exercise seven times per week. However, our data suggested that exercising with ES-assisted cycling only three times per week could also have bene®cial e ects on glucose metabolism in people with SCI.…”

“…Since then, research has clearly shown physiological bene®ts with ES-assisted cycling with respect to cardiovascular, 32 ± 35 muscular, 36 ± 38 pulmonary 39 ± 41 and hormonal adaptations. 42,43 However, there are very limited studies examining the e ects of ES-assisted exercise on insulin sensitivity in people with SCI. Therefore, the purpose of the study was to investigate the e ect of ES-assisted cycling on glucose tolerance and insulin sensitivity in people with SCI.…”

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

“…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.…”

Patient perception of the impact of sporting activity on rehabilitation in a spinal cord injuries unit

“…6 Risk factors for cardiovascular disease are ameliorated in spinal cord-injured individuals by exercise with reported increased cardiac dimensions, 7 higher maximal work rate, 7 increase in peak oxygen consumption, 8 reduced breathlessness, 9 and improved lipid profiles and glucose metabolism. [10][11][12] The emphasis on patient-centred goal setting and patient involvement in rehabilitation planning in current practice suggests the importance of patients' perception of the value of a given activity. We wished to establish the perception of the role of sporting activity in rehabilitation and in general health among patients who had recently undergone rehabilitation in a SCI unit (SCIU).…”