Effect of training intensity on physical capacity, lipid profile and insulin sensitivity in early rehabilitation of spinal cord injured individuals

STUDY DESIGN: Pre-post training intervention. OBJECTIVES: To evaluate the effect of training intensity on physical capacity, lipid profile and insulin sensitivity in early rehabilitation of spinal cord injured (SCI) patients, and to assess the correlation between peak aerobic capacity (VO(2Peak)) and insulin sensitivity. SETTING: Spinal Cord Rehabilitation Unit, Sunnaas Hospital, Nesoddtangen, Norway. METHOD: Six recently injured SCI individuals participated in the arm training intervention and were randomly admitted to a high-intensity (HI; 70-80% heart rate reserve (HRR)) and low-intensity (LI; 40-50% HRR) group. The 1 h interval training consisted of 3 min exercise bouts interspersed with 2 min of rest, three times a week for 8 weeks. In addition, a correlation coefficient was obtained between VO(2Peak) and insulin sensitivity in 11 SCI patients. RESULTS: The 8-week training program resulted in a significant increase in VO(2Peak) and maximal power output (PO(Max)) for the group as a whole (P<0.05). VO(2Peak) increased significantly more and total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C) ratio and triglycerids decreased significantly more in the HI group than in the LI group (P=0.05). Training-induced changes in insulin sensitivity were significantly different between the groups (P=0.05), which was due to a nonsignificant decline in insulin sensitivity in the HI group and a nonsignificant improvement in the LI group. A significant positive correlation was found between VO(2peak) and insulin sensitivity (r=0.68, P=0.02). CONCLUSION: The interval arm training protocol as used in the present study enables recently injured SCI patients to do substantial work at a relatively high intensity. Results indicate that improvements in physical capacity and lipid profile were more pronounced in response to high-intensity training. The significant correlation between maximal oxygen consumption and insulin sensitivity indicates that, as in the able-bodied population, peak aerobic capacity is a predictive value with regard to insulin sensitivity in SCI. Future studies with larger groups assessing the role of exercise intensity on insulin sensitivity in SCI are suggested.     

Attenuation of natural killer cell activity during 2-h exercise in individuals with spinal cord injuries

DESIGN: Non-randomized study. OBJECTIVE: To determine natural killer cell cytotoxic activity (NKCA) to 2-h arm ergometer exercise in persons with spinal cord injuries (SCI) and the underlying mechanism of such response. SETTING: University of Occupational and Environmental Health, Japan. METHODS: We examined NKCA response to 2-h arm crank ergometer exercise at 60% of maximum oxygen consumption (VO(2max)) in SCI and able-bodied persons. NKCA and plasma concentrations of prostaglandin E(2) (PGE(2)), adrenaline and cortisol were measured before, during and immediately after the exercise. The study included seven subjects with SCI between Th11 and L4 and six able-bodied persons. RESULTS: NKCA in able-bodied subjects increased (P<0.05) at 60 min of exercise and immediately after the exercise, and remained elevated up to 2 h after exercise. However, NKCA in SCI decreased (P<0.05) immediately after exercise but recovered at 2 h after exercise. Plasma adrenaline in both groups increased significantly (P<0.05) immediately after exercise and returned to baseline level 2 h after the exercise. Plasma cortisol in both groups remained constant throughout the study. In SCI, PGE(2) significantly increased immediately after 2 h exercise and returned to the baseline level 2 h after exercise; however, it remained unchanged during the test in able-bodied subjects. CONCLUSION: Our results suggested that increase of PGE(2) in SCI partially contributes to NKCA.     

Intensive exercise may preserve bone mass of the upper limbs in spinal cord injured males but does not retard demineralisation of the lower body

STUDY DESIGN: Cross-sectional study comparing a group of active spinal cord injured (SCI) males carefully matched for age, height, and weight with active able-bodied male controls. OBJECTIVES: To compare bone mass of the total body, upper and lower limbs, hip, and spine regions in active SCI and able-bodied individuals. SETTING: Outpatient study undertaken in two centres in New Zealand. METHODS: Dual energy X-ray absorptiometry (DEXA) scanning was used to determine bone mass. Questionnaires were used to ascertain total time spent in weekly physical activity for each individual. The criterion for entry into the study was regular participation in physical activity of more than 60 min per week, over and above that required for rehabilitation. RESULTS: Seventeen SCI and their able-bodied controls met our required activity criterion. Bone mineral density (BMD) values of the total body and hip regions were significantly lower in the SCI group than in their controls (P=0.0001). Leg BMD and bone mineral content (BMC) were also significantly lower in the SCI group (P=0.0001). By contrast, lumbar spine BMD and arm BMD and BMC did not differ between the SCI and control groups. Arm BMD and BMC were greater (not significant) than the reference norms (LUNAR database) for both groups. CONCLUSION: Intensive exercise regimens may contribute to preservation of arm bone mass in SCI males, but does not prevent demineralisation in the lower body.     

Comparison of blood lactate elimination in individuals with paraplegia and able-bodied individuals during active recovery from exhaustive exercise

BACKGROUND/OBJECTIVE: The aim of the present study was to compare blood lactate elimination between individuals with paraplegia (P) and able-bodied (AB) individuals after strenuous arm exercise. METHODS: Eight P and 8 AB men (matched for age, height, and weight) participated in this study. Average weekly arm-training volume for P participants (eg, hand bike, wheelchair basketball) and AB participants (eg, swimming, rowing, cross-country skiing) was 4.1 +/- 1.6 vs 2.8 +/- 0.8 h. A maximal-arm-cranking intensity-graded exercise test to volitional exhaustion was performed by all test participants. Immediately after the exercise test, the participants performed arm cranking for another 30 minutes at a workload of one third of the maximally achieved power output. During this active recovery, mixed-capillary blood samples were taken for lactate analysis. RESULTS: The lactate accumulation constant was significantly higher for P individuals, whereas the lactate elimination constant showed no significant difference between the two groups. CONCLUSIONS: Individuals with paraplegia seem to have no disadvantages in lactate elimination after exhaustive arm exercise compared with able-bodied individuals.     

Comparison of asynchronous versus synchronous arm crank ergometry.

STUDY DESIGN: A direct comparison of synchronous versus asynchronous arm crank ergometry has not been carried out previously. Therefore, a comparative research design was employed. OBJECTIVE: To assess the physiological responses of arm cranking when performed asynchronously (arms moving opposite to each other) versus synchronously (both arms moving in the same direction simultaneously). SETTING: A university hospital setting in Galveston, Texas, USA. METHODS: Seventeen individuals between the ages of 19 and 53 years were studied, 11 with paraplegia and six with no apparent disability. Two maximal arm crank graded exercise tests were performed with the subject seated in a wheelchair. Testing consisted of both arms (1) asynchronously (reciprocally) pushing and pulling the crank handles and (2) pushing and pulling the crank handles synchronously. Each test consisted of 2 min stages starting at 20 W and increasing 10 W per stage thereafter until exhaustion. Heart rate, oxygen consumption, and minute ventilation were measured and recorded during each stage. Blood lactate levels were monitored before and after each test. Statistical analysis was performed using the multivariate Hotelling's T2 followed by post hoc univariate tests. RESULTS: Greater power and longer test times (both groups, P<0.05) and higher post test blood lactates (nondisabled P<0.01, paraplegic P<0.05) were achieved with asynchronous cranking versus synchronous cranking. While submaximal responses were similar between the two modes of cranking, there was a tendency for all variables to be lower with asynchronous. All subjects preferred asynchronous rather than synchronous cranking. CONCLUSION: Despite few statistically significant differences, based on the subjective reports from all subjects, we believe there is a clinically significant difference between the two modes of cranking. The results suggest that the mode of cranking may have implications for arm crank testing, training, and functional locomotion in individuals with lower extremity impairments.     

Incidence and clinical correlates of increased serum creatine kinase levels in persons with spinal cord injury

BACKGROUND: Elevated plasma levels of creatine kinase (CPK) are found in various neuromuscular conditions as a result of muscle damage and necrosis. Elevated CPK has also been described in elite wheelchair athletes and in able-bodied individuals after strenuous exercise. METHODS: The incidence of elevated CPK in individuals with spinal cord injury (SCI) has not been well established. We reviewed laboratory data from 581 individuals with chronic SCI. RESULTS: Most individuals with SCI (73.3%) had CPK values within 95% confidence intervals for able-bodied individuals. The highest levels were seen in African Americans (21% had CPK values > 95 confidence intervals for able-bodied individuals). Significant associations between CPK and the following independent variables were identified: impairment group, gender, duration of injury, body mass index, and ethnic group. Multiple regression analysis revealed significant correlations between CPK and oxygen consumption (beta .37, P < .01) in 32 individuals who performed the exercise test. CONCLUSIONS: These findings are important for clinicians evaluating symptoms of fatigue and myopathy in individuals with SCI.     

Kinetics and steady-state of VO2 responses to arm exercise in trained spinal cord injury humans

STUDY DESIGN: Cross-sectional study comparing trained spinal cord injured (SCI) subjects (lesion level: L1 - T6) with healthy young subjects (CONT). OBJECTIVE: To investigate the kinetics of response in oxygen uptake (VO(2)) in human upper-body skeletal muscles, nine trained SCI subjects underwent submaximal supine arm exercises. METHOD: The SCI subjects underwent an incremental arm exercise test until exhaustion. The days after this first round of testing, breath-by-breath VO(2) and beat-by-beat heart rate (HR) on- and off-kinetics were determined during three repetitions of constant exercise at 50% of VO(2peak). The overall time course of response was determined from the half time (t(1/2)). Increased capillary blood lactate production (delta[La]b) at the onset of exercise was defined as the difference between at rest and at the end of exercise. Cardiac output (Q) was measured using the acetylene rebreathing method during the steady state of exercise. In accordance with the Fick principle, the difference in arterial-venous O(2) content (Ca-vO(2)) was defined as VO(2)/Q. RESULTS: During the steady state of the submaximal arm exercise, a more significant increase in the steady state of Q was obtained in the CONT subjects than in the trained SCI subjects: respectively, 14.9+/-1.4 l/min versus (12.7+/-0.8 l/min). There was no difference in the steady state of VO(2) between the two groups; as a result, SCI subjects had the greater Ca-v(2). Meanwhile, VO(2) on- and off-kinetics became much faster in the trained SCI subjects than in the CONT subjects. In addition, t(1/2) HR on-kinetics was not significantly different between the SCI and CONT groups. Increased Delta[La]b was closely related to larger t(1/2) VO(2) on-kinetics (r = 0.624, P < 0.05). CONCLUSION: It is concluded that the acceleration of VO(2) on- and off-kinetics in the trained SCI subjects was observed even though there was no difference in HR on- and off-kinetics between the SCI and CONT groups and a lower steady state of Q in the trained SCI subjects. VO(2) kinetics would therefore be the limiting factor in oxidative phosphorylation in the upper skeletal muscles, thereby providing a lower lactic O(2)-deficit (ie delta[La]b).     

Effect of harness application and postural changes on cardiovascular parameters of individuals with spinal cord injury

STUDY DESIGN: Prospective assessment of cardiovascular parameters in individuals with spinal cord injury (SCI) in response to harness application and postural changes including orthostatic stress. OBJECTIVE: To evaluate arterial blood pressure and heart rate (HR) with and without harness application during sitting, supine, and standing positions in able-bodied and SCI individuals. METHODS: Measurements were obtained in all SCI research participants (n=11) before a locomotor training intervention and compared to data with able-bodied individuals (n=9). During standing, all research participants wore a harness and were suspended by an overhead, pneumatic body weight support system. RESULTS: Resting arterial blood pressure and HR in individuals with cervical SCI were significantly lower during sitting than in thoracic SCI and able-bodied individuals (P<0.05). Orthostatic stress significantly decreased arterial blood pressure only in individuals with cervical SCI (P<0.05). Harness application had no effect on cardiovascular parameters in able-bodied individuals, whereas diastolic blood pressure was significantly increased in those with SCI. Orthostatic changes in cervical SCI when sitting were ameliorated by harness application. However, while standing with harness, individuals with cervical SCI still developed orthostatic hypotension. CONCLUSIONS: Level of injury to the spinal cord influences baseline cardiovascular parameters. Application of harness in individuals with SCI could alter baseline cardiovascular parameters and the response to orthostatic stress. This should be carefully considered when assessing effects of therapeutic interventions using body weight support in individuals with SCI.     

Functional community ambulation requirements in incomplete spinal cord injured subjects.

STUDY DESIGN: A group of people with incomplete spinal cord injuries (SCI) were evaluated and compared with able-bodied individuals during several walking conditions. OBJECTIVES: To evaluate the functional community ambulation and estimated energy expenditure in persons with incomplete SCI and able-bodied individuals. METHODS: A list of criteria was used to evaluate functional community ambulation among participants. Physiological variables, such as the heart rate, oxygen uptake and the lactate concentration, were also measured. RESULTS: Three of nine incomplete SCI subjects and all able-bodied subjects were able to meet all the criteria measured. The required velocity to safely cross an intersection was the criterion that the incomplete SCI group had the most difficulty reaching. The able-bodied subjects had a comfortable walking velocity twice that of the incomplete SCI subjects' preferred velocity. When walking at the same velocity (incomplete SCI subjects' preferred velocity), the incomplete SCI subjects had a rate of oxygen uptake 26% greater than the healthy subjects and were 200% less efficient. The lactate concentration also proved to be a useful tool when evaluating the incomplete SCI subjects' walking efficiency. The incomplete SCI subjects lactate concentration increased after walking at their preferred velocity, meaning that the anaerobic pathways were used to meet energy demands. CONCLUSION: Rehabilitation centers should adapt their evaluation forms and increase their criteria requirements to more suitable criteria that are found in the SCI patient's community. The physiological cost should also be taken into consideration when evaluating the SCI patient's functional ambulation.     

Cardiovascular response to peak voluntary exercise in males with cervical spinal cord injury

Context/Objective: Traumatic damage to the cervical spinal cord is usually associated with a disruption of the autonomic nervous system (ANS) and impaired cardiovascular control both during and following exercise. The magnitude of the cardiovascular dysfunction remains unclear. The aim of the current study was to compare cardiovascular responses to peak voluntary exercise in individuals with tetraplegia and able-bodied participants.

Design: A case-control study.

Subjects: Twenty males with cervical spinal cord injury (SCI) as the Tetra group and 27 able-bodied males as the Control group were included in the study.

Outcome Measures: Blood pressure (BP) response one minute after the peak exercise, peak heart rate (HR_peak), and peak oxygen consumption (VO_2peak) on an arm crank ergometer were measured. In the second part of the study, 17 individuals of the Control group completed the Tetra group's workload protocol with the same parameters recorded.

Results: There was no increase in BP in response to the exercise in the Tetra group. Able-bodied individuals exhibited significantly increased post-exercise systolic BP after the maximal graded exercise test (123±16%) and after completion of the Tetra group's workload protocol (114±11%) as compared to pre-exercise. The Tetra group VO_2peak was 59% and the HR_peak was 73% of the Control group VO_2peak and HR_peak, respectively.

Conclusions: BP did not increase following maximal arm crank exercise in males with a cervical SCI unlike the increases observed in the Control group. Some males in the Tetra group appeared to be at risk of severe hypotension following high intensity exercise, which can limit the ability to progressive increase and maintain high intensity exercise.     

Higher glucose uptake in paralysed spastic leg

BACKGROUND: Insulin resistance and diabetes mellitus have been reported in the spinal cord injured (SCI). The group exhibits risk factors, as decreased physical activity, as well as episodes of stimulation of sympathetic nervous system below the level of lesion known to stimulate lipolysis, which in turn could induce insulin resistance. However, data are inconsistent, which might indicate the presence of protective mechanisms. OBJECTIVE: To investigate the glucose uptake in spastic paralysed SCI legs compared to able-bodied. To investigate regional differences between glucose handling in the arm and leg. STUDY DESIGN: Experimental controlled study. SETTINGS: Institution of Clinical Neuroscience and Physiology, Spinal Injures Unit, Sahlgrens University Hospital, Goteborg, Sweden. METHODS: Nine SCI subjects (2 C7, 7 T1-T4 ASIA A: 8, ASIA B: 1) were compared to 10 weight- and age-matched controls. Plasma flow in arm and leg was analysed by venous occlusion strain gauge plethysmography, and plasma derived from artery and veins in the arm and leg was analysed for glucose, insulin and lactate during fasting resting conditions. RESULTS: Glucose uptake was higher in SCI legs compared to controls. There was no difference in insulin uptake or lactate production. Plasma flow was higher in SCI legs compared to controls. Controls showed a higher glucose uptake and lactate production in arm than leg. CONCLUSIONS: Spasticity may counteract the risk of diabetes by inducing an insulin-independent glucose uptake. The regional difference in metabolism in able-bodied make it hazardous to do generalizations to whole body metabolism from arm or leg measurements.     

Low-frequency fatigue in individuals with spinal cord injury

BACKGROUND/OBJECTIVE: This study examined magnitude and recovery of low-frequency fatigue (LFF) in the quadriceps after electrically stimulated contractions in spinal cord-injured (SCI) and able-bodied subjects. SUBJECTS: Nine SCI (ASIA A-C, levels C5-T9, injured 13.6 +/- 12.2 years) and 9 sedentary able-bodied subjects completed this study. METHODS: Fatigue was evoked in 1 thigh, and the nonfatigued leg served as a control. The fatigue test for able-bodied subjects lasted 15 minutes. For SCI, stimulation was adjusted so that the relative drop in force was matched to the able-bodied group. Force was assessed at 20 (P20) and 100 Hz (P100), and the ratio of P20/P100 was used to evaluate LFF in thighs immediately after, at 10, 20, and 60 minutes, and at 2, 4, 6, and 24 hours after a fatigue test. RESULTS: The magnitude of LFF (up to 1 hour after fatigue) was not different between able-bodied and patients with SCI. However, recovery of LFF over 24 hours was greater in able-bodied compared with patients with SCI in both the experimental (P < 0.001) and control legs (P < 0.001). The able-bodied group showed a gradual recovery of LFF over time in the experimental leg, whereas the SCI group did not. CONCLUSIONS: These results show that individuals with SCI are more susceptible to LFF than able-bodied subjects. In SCI, simply assessing LFF produced considerable LFF and accounted for a substantial portion of the response. We propose that muscle injury is causing the dramatic LFF in SCI, and future studies are needed to test whether "fatigue" in SCI is actually confounded by the effects of muscle injury.     

Acute effects of locomotor training on overground walking speed and H-reflex modulation in individuals with incomplete spinal cord injury

OBJECTIVE: The purpose of this study was to assess the effect of a single bout of a locomotor-training paradigm on overground walking speed and H-reflex modulation of individuals with incomplete spinal cord injury (SCI). METHODS: Self-selected and maximum walking speeds and soleus H-reflexes (H/M ratios) during standing and stance and swing phases of walking (self-selected velocity) were obtained from 4 individuals with American Spinal Injury Association impairment classification D. Data were collected immediately before and after a single bout of locomotor training with body weight support on a treadmill. The pretraining H/M ratios of the SCI subjects were also compared with values from 4 able-bodied subjects who did not receive the intervention. Maximum H/M ratios while standing and during midstance and midswing phases of overground walking were considerably greater in the SCI subjects than in the control subjects. RESULTS: After the single bout of training, self-selected and maximum overground walking speeds of the subjects with SCI increased by 26% and 25%, respectively. Furthermore, H-reflexes were significantly more depressed in the SCI subjects during overground walking (28% less during stance, 34% less during swing). CONCLUSIONS: Although preliminary, these findings indicate that a single bout of locomotor training produced immediate increases in walking velocity and acute neurophysiologic changes in individuals with incomplete SCI.     

Incidence And Clinical Correlates Of Increased Serum Creatine Kinase Levels In Persons With Spinal Cord Injury

Abstract

Background: Elevated plasma levels of creatine kinase (CPK) are found in various neuromuscular conditions as a result of muscle damage and necrosis. Elevated CPK has also been described in elite wheelchair athletes and in able-bodied individuals after strenuous exercise.

Methods: The incidence of elevated CPK in individuals with spinal cord injury (SCI) has not been well established. We reviewed laboratory data from 581 individuals with chronic SCI.

Results: Most individuals with SCI (73.3%) had CPK values within 95% confidence intervals for able-bodied individuals. The highest levels were seen in African Americans (21% had CPK values > 95 confidence intervals for able-bodied individuals). Significant associations between CPK and the following independent variables were identified: impairment group, gender, duration of injury, body mass index, and ethnic group. Multiple regression analysis revealed significant correlations between CPK and oxygen consumption (beta .37, P < .01) in 32 individuals who performed the exercise test.

Conclusions: These findings are important for clinicians evaluating symptoms of fatigue and myopathy in individuals with SCI.     

Pulse Wave Velocity for Assessment of Arterial Stiffness Among People With Spinal Cord Injury: A Pilot Study

Background/Objective: The most significant complication and leading cause of death for people with spinal cord injury (SCI) is coronary artery disease (CAD). It has been confirmed that aortic pulse wave velocity (PVW) is an emerging CAD predictor among able-bodied individuals. No prior study has described PWV values among people with SCI. The objective of this study was to compare aortic (the common carotid to femoral artery) PWV, arm (the brachial to radial artery) PVW, and leg (the femoral to posterior tibial artery) PVW in people with SCI (SCI group) to able-bodied controls (non-SCI group).

Methods: Participants included 12 men with SCI and 9 non-SCI controls matched for age, sex, height, and weight. Participants with a history of CAD or current metabolic syndrome were excluded. Aortic, arm, and leg PVW was measured using the echo Doppler method.

Results: Aortic PVW (mean ± SD) in the SCI group (1,274 ± 369 cm/s) was significantly higher (P < 0.05) than in the non-SCI group (948 ± 110 cm/s). There were no significant between-group differences in mean arm PVW (SCI: 1,152 ± 193 cm/s, non-SCI: 1,237 ± 193 cm/s) or mean leg PVW (SCI: 1,096 ± 1 73 cm/s, non-SCI: 994 ±178 cm/s) values.

Conclusions: Aortic PVW was higher among the SCI group compared with the non-SCI group. The higher mean aortic PVW values among the SCI group compared with the non-SCI group indicated a higher risk of CAD among people with SCI in the absence of metabolic syndrome.     

Acute Effects Of Locomotor Training on Overground Walking Speed and H-Reflex Modulation in Individuals with Incomplete Spinal Cord Injury

Abstract

Objective: The purpose of this study was to assess the effect of a single bout of a locomotor-training paradigm on overground walking speed and H-reflex modulation of individuals with incomplete spinal cord injury (SCI).

Methods: Self-selected and maximum walking speeds and soleus H-reflexes (H/M ratios) during standing and stance and swing phases of walking (self-selected velocity) were obtained from 4 individuals with American Spinal Injury Association impairment classification D. Data were collected immediately before and after a single bout of locomotor training with body weight support on a treadmill. The pretraining H/M ratios of the SCI subjects were also compared with values from 4 able-bodied subjects who did not receive the intervention. Maximum H/M ratios while standing and during midstance and midswing phases of overground walking were considerably greater in the SCI subjects than in the control subjects.

Results: After the single bout of training, self-selected and maximum overground walking speeds of the subjects with SCI increased by 26% and 25%, respectively. Furthermore, H-reflexes were significantly more depressed in the SCI subjects during overground walking (28% less during stance, 34% less during swing).

Conclusions: Although preliminary, these findings indicate that a single bout of locomotor training produced immediate increases in walking velocity and acute neurophysiologic changes in individuals with incomplete SCI.     

Low-Frequency Fatigue in Individuals With Spinal Cord Injury

Abstract

Background/Objective: This study examined magnitude and recovery of low-frequency fatigue (LFF) in the quadriceps after electrically stimulated contractions in spinal cord-injured (SCI) and able-bodied subjects.

Subjects: Nine SCI (ASIA A-C, levels C5-T9, injured 13.6 ± 12.2 years) and 9 sedentary able-bodied subjects completed this study.

Methods: Fatigue was evoked in 1 thigh, and the nonfatigued leg served as a control. The fatigue test for able-bodied subjects lasted 15 minutes. For SCI, stimulation was adjusted so that the relative drop in force was matched to the able-bodied group. Force was assessed at 20 (P20) and 100 Hz (PI 00), and the ratio of P20/P100 was used to evaluate LFF in thighs immediately after, at 10, 20, and 60 minutes, and at 2, 4, 6, and 24 hours after a fatigue test.

Results: The magnitude of LFF (up to 1 hour after fatigue) was not different between able-bodied and patients with SCI. However, recovery of LFF over 24 hours was greater in able-bodied compared with patients with SCI in both the experimental (P < 0.001) and control legs (P < 0.001). The able-bodied group showed a gradual recovery of LFF over time in the experimental leg, whereas the SCI group did not.

Conclusions: These results show that individuals with SCI are more susceptible to LFF than able-bodied subjects. In SCI, simply assessing LFF produced considerable LFF and accounted for a substantial portion of the response. We propose that muscle injury is causing the dramatic LFF in SCI, and future studies are needed to test whether “fatigue” in SCI is actually confounded by the effects of muscle injury.     

Carbohydrate and lipid metabolism in chronic spinal cord injury

BACKGROUND: Abnormalities of carbohydrate and lipid metabolism are more common in the spinal cord injury (SCI) population than in the able-bodied population. This is an important consideration in the long-term care of individuals with SCI. DESIGN: Literature review. FINDINGS: When compared with the able-bodied population, people with SCI are more likely to have oral carbohydrate intolerance, insulin resistance, elevated low-density lipoprotein cholesterol, and reduced high-density lipoprotein cholesterol, associated with increased prevalences of diabetes mellitus and cardiovascular disease. CONCLUSIONS: Because of increased risk factors for diabetes mellitus and heart disease in individuals with SCI, modifiable risk factors should be addressed, eg, obesity, inactivity, dietary factors, and smoking. To reduce mortality and morbidity associated with these risk factors, periodic screening for carbohydrate and lipid abnormalities is recommended, with appropriate therapeutic interventions.     

Influence of upper- and lower-limb exercise training on cardiovascular function and walking distances in patients with intermittent claudication

PURPOSE: The effects of upper-limb (arm cranking) and lower-limb (leg cranking) exercise training on walking distances in patients with intermittent claudication was assessed. METHODS: Sixty-seven patients (33 to 82 years old) with moderate to severe intermittent claudication were recruited, and the maximum power generated during incremental upper- and lower-limb ergometry tests was determined, as were pain-free and maximum walking distances (by using a shuttle walk test). Patients were randomly assigned to an upper-limb training group (n = 26) or a lower-limb training group (n = 26). An additional untrained group (n = 15) was recruited on an ad hoc basis in parallel with the main trial by using identical inclusion criteria. This group was subsequently shown to possess a similar demographic distribution to the two exercise groups. Supervised training sessions were held twice weekly for 6 weeks. RESULTS: Both training programs significantly improved the maximum power generated during the incremental upper- and lower-limb ergometry tests (P <. 001), which may reflect an increase in central cardiovascular function that was independent of the training mode. More importantly, pain-free and maximum walking distances also improved in both training groups (P <.001). The improvements in the training groups were similar; there were no changes in the untrained control group. These findings suggest that the symptomatic improvement after upper-limb exercise training may result, in part, from systemic cardiovascular effects rather than localized metabolic or hemodynamic changes. CONCLUSION: Carefully prescribed upper-limb exercise training can evoke a rapid symptomatic improvement in patients with claudication, while avoiding the physical discomfort experienced when performing lower-limb weight-bearing exercise.