Quadriceps muscle deoxygenation during functional electrical stimulation in adults with spinal cord injury

STUDY DESIGN: Cross-sectional study comparing healthy subjects with age and gender matched subjects with spinal cord injury (SCI, injury levels from C5 to T12). OBJECTIVES: To compare the acute cardiorespiratory responses and muscle oxygenation trends during functional electrical stimulation (FES) cycle exercise and recovery in the SCI and healthy subjects exercising on a mechanical cycle ergometer. SETTING: Seven volunteers in each group participated in one exercise test at the Rick Hansen Center, University of Alberta, Edmonton, Canada. METHODS: Both groups completed a stagewise incremental test to voluntary fatigue followed by 2 min each of active and passive recovery. Cardiorespiratory responses were continuously monitored using an automated metabolic cart and a wireless heart rate monitor. Tissue absorbency, an index of muscle oxygenation, was monitored non-invasively from the vastus lateralis using near infrared spectroscopy. RESULTS: The healthy subjects showed significant (P<0.05) increases in the oxygen uptake (VO2), heart rate (HR) and ventilation rate (VE) from rest to maximal exercise. The SCI subjects showed a twofold increase in VO2 (P>0.05), a threefold increase in VE (P<0.05) and a 5 beats/min increase in HR (P>0.05) from the resting value. The SCI subjects demonstrated a lesser degree (P<0.05) of muscle deoxygenation than the healthy subjects during the transition from rest to exercise. Regression analysis indicated that the rate of decline in muscle deoxygenation with respect to the VO2 was significantly (P<0.05) faster in the SCI subjects compared to healthy subjects. CONCLUSIONS: FES exercise in SCI subjects elicits: (a) modest increases in the cardiorespiratory responses when compared to resting levels; (b) lower degree of muscle deoxygenation during maximal exercise, and (c) faster changes in muscle deoxygenation with respect to the VO2 during exercise when compared to healthy subjects.     

Lipid profiles are influenced by arm cranking exercise and training in individuals with spinal cord injury

STUDY DESIGN: A prospective, two-group comparative intervention study. OBJECTIVE: To determine the acute and training effects of arm cranking exercise on blood lipid profiles in wheel chair bound individuals with spinal cord injury (SCI) and normal able-bodied subjects. SETTING: Faculty of Science, School of Sport and Exercise Science, Liverpool John Moores University, England. METHODS: Total cholesterol, triglyceride and high-density lipoprotein cholesterol (HDL-C) at rest and in response to arm cranking exercise before and after 12 weeks of training were compared between individuals with SCI (N = 5) and able-bodied subjects (N = 7). Following the determination of peak oxygen consumption (VO2peak), all subjects performed a submaximal arm cranking exercise at an intensity corresponding to 60-65% VO2peak for 30 min. Venous blood samples were obtained before and after submaximal exercise and measured for total cholesterol, triglycerides and HDL-C concentrations. These lipid parameters were remeasured in all subjects at rest and in response to the same submaximal arm cranking exercise after 12 weeks of individually supervised arm cranking training programme. RESULTS: Before training, the resting mean value of triglyceride in individuals with SCI was significantly (P < 0.05) higher than that found in able-bodied persons. Acute arm cranking exercise did not change total cholesterol or triglyceride concentrations in either the SCI or the able-bodied groups. However, HDL-C increased significantly following exercise in the able-bodied subjects. Following training, the resting mean value of total cholesterol in the group with SCI was significantly (P < 0.05) higher compared with able-bodied individuals. Furthermore, the resting and post submaximal arm cranking exercise mean values of total cholesterol in the able-bodied group, but not in the group with SCI, were significantly lower than those observed before training. While the resting mean value of HDL-C before training in the group with SCI was lower than that found in the able-bodied, this difference did not reach the designated level of significance (P > 0.05). Submaximal arm cranking exercise was followed by a significant increase in HDL-C only in the able-bodied individuals. Compared to pretraining, the resting and post arm cranking exercise levels of HDL-C in the group with SCI increased significantly (P < 0.05) after training. CONCLUSION: It is concluded that acute arm cranking exercise and training in individuals with SCI is associated with favourable effects on HDL-C, whereas total cholesterols and triglycerides were not altered. The mechanism responsible for the increase in HDL-C with training in individuals with SCI is not known, but it is likely to be related to increased activity of cholesterol transport enzymes lipoprotein lipase and acyltransferase.     

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.     

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.     

Optimal exercise intensities for fat metabolism in handbike cycling and cycling

STUDY DESIGN: Energy expenditure (EE) and fat oxidation in handbike cycling compared to cycling in order to determine the intensity that elicits maximal fat oxidation in handbike cycling. OBJECTIVE: To establish the exercise intensity with the highest fat oxidation rate in handbike cycling compared with cycling (control group) in order to give training recommendations for spinal cord-injured (SCI) athletes performing handbike cycling. SETTING: Institute of Sports Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland. METHODS: Eight endurance-trained handbike cyclists (VO2 peak(handbike cycling) 37.5+/-7.8 ml/kg/min) and eight endurance trained cyclists (VO2 peak(cycling) 62.5+/-4.5 ml/kg/min) performed three 20-min exercise blocks at 55, 65 and 75% VO2 peak in handbike cycling on a treadmill or in cycling on a cycling ergometer, respectively, in order to find the intensity with the absolutely highest fat oxidation. RESULTS: The contribution of fat to total EE was highest (39.1+/-16.3% EE) at 55% VO2 peak in handbike cycling compared to cycling, where highest contribution of fat to EE (50.8+/-13.8%) was found at 75% VO2 peak. In handbike cycling, the highest absolute fat oxidation (0.28+/-0.10 g/min) was found at 55% VO2 peak compared to cycling, where highest fat oxidation (0.67+/-0.20 g/min) was found at 75% VO2 peak. CONCLUSION: Well-trained handbike cyclists have their highest fat oxidation at 55% VO2 peak(handbike cycling) compared to well-trained cyclists at 75% VO2 peak(cycling). Handbike cyclists should perform endurance exercise training at 55% VO2 peak(handbike cycling), whereas well-trained cyclists should be able to exercise at 75% VO2 peak(cycling). For training recommendations, the heart rate at 55% VO2 peak(handbike cycling) lies at 135+/-6 bpm in handbike cycling in SCI compared to 147+/-14 bpm at 75% VO2 peak(cycling) in well-trained cyclists. We presume that the reduced muscle mass involved in exercise during handbike cycling is the most important factor for impaired fat oxidation compared to cycling. But also other factors as fitness level and haemodynamic differences should be considered. Our results are only applicable to well-trained handbike cyclists with SCI and not for the general SCI population.     

Cardiorespiratory responses during passive walking-like exercise in quadriplegics

STUDY DESIGN: Cross-sectional and comparative investigation using quadriplegics (QP) and nondisabled subjects (ND). OBJECTIVE: To evaluate cardiorespiratory responses during passive walking-like exercise (PWE) in QP. SETTING: National Rehabilitation Center for Persons with Disabilities in Japan. METHOD: The subjects were seven male QP with complete lesion (age: 27.0 +/- 5.4, injured level: C6-C7) and six male ND (age: 26.3 +/- 4.5). Cardiorespiratory responses were measured until voluntary fatigue during PWE, the rhythmical activity of paralyzed lower limbs synchronized with arm movements. RESULTS: There were no significant differences in oxygen consumption (VO(2)), pulmonary ventilation (VE), heart rate (HR) and oxygen pulse (O(2) pulse) between QP and ND during PWE. ND showed increased ventilatory equivalent for oxygen (VE/VO(2) ratio) during exercise, while QP showed a significantly greater respiratory rate (RR) during exercise than ND (P < 0.05). CONCLUSION: PWE elicited an increase in VO(2) with workload increment in QP similar to ND. However, higher RR suggested the intrinsic dysfunction of RR control during submaximal exercise in QP. From these results, it was thought that respiratory response would be the restriction factor of efficient oxygen transportation during PWE in QP.     

Effect of lesion level on the orthotic gait performance in individuals with complete paraplegia

STUDY DESIGN: Cross-sectional, experimental research. OBJECTIVES: To clarify the effect of lesion level on cardio-respiratory responses and biomechanical characteristics of walking with a reciprocating gait orthosis in complete paraplegia with spinal cord injury (SCI). SETTING: National Rehabilitation Center for Persons with Disabilities, Japan. METHODS: Ten SCI individuals (age: 20-34 years, injured level: Th5-12) who experienced orthotic gait training at least for 10 weeks participated in two experiments: (1) measurement of the cardiorespiratory responses during 20 min of orthotic gait exercise; and (2) three-dimensional motion analysis and ground reaction force measurement using the VICON system. We calculated the following parameters: pulmonary ventilation, oxygen consumption (VO(2)), heart rate (HR), gait speed, cadence, stride length, crutch force (CF), hip range of motion (ROM), and hip angular velocity (VEL). Further, energy consumption and energy cost were calculated using the steady-state value of VO(2) and gait speed. RESULTS: The steady-state value of the VO(2) (18.2 +/- 3.80 ml/kg) and HR (133.0 +/- 21.63 b/min) tended to be larger in higher thoracic SCI subjects. There were strong positive correlations between the lesion level and walking speed (r = 0.74), energy cost (r = 0.85), and hip ROM (r = 0.78). On the other hand, negative correlation between the lesion level and peak CF (r = -0.78) was clarified. CONCLUSIONS: The physiological intensity of the orthotic gait strongly depended on the level of lesion. It seems likely that a limited hip range of motion and excess upper limb load result in the low energy cost of orthotic gait for the higher thoracic level of paraplegic patients.     

Potential impact of orthotic gait exercise on natural killer cell activities in thoracic level of spinal cord-injured patients

STUDY DESIGN: Prospective before-after trial. OBJECTIVE: To examine the changes of natural killer (NK) cell activity in response to orthotic gait exercise in thoracic level of spinal cord-injured (SCI) patients. SETTING: National Rehabilitation Center for Persons with Disabilities, Japan. METHODS: In all, 10 thoracic level of SCI patients (ranging Th5-Th12), who experienced orthotic gait training, participated in this study. NK cell activity at an effector:target (E/T) ratio (20:1) was examined in a sample of peripheral blood taken before and just after orthotic gait exercise for 20 min. On a separate day, to evaluate the physical intensity of the orthotic gait exercise, cardiorespiratory responses at rest and during exercise were measured. RESULTS: The resting value of the NK cell activity in our SCI patients was remarkably lower than that in normal subjects reported in previous studies. The NK cell activity was significantly increased through a 20 min orthotic gait exercise (pre versus post; 12.7+/-5.28 versus 17.76+/-6.71, P<0.05). The steady-state value of oxygen (VO2) and heart rate (HR) were 18.13+/-3.92 ml/kg and 142.53+/-19.84 b/min, respectively. It was noteworthy that a patient who showed decrement of NK cell activity in response to exercise had the highest level of injury (Th5), and showed the higher energy cost of orthotic gait. CONCLUSION: These findings suggested that the orthotic gait exercise has the potential to enhance the immune function for SCI persons, although patients with a higher level of SCI may have some difficulties. SPONSORSHIP: Mitsui Sumitomo Insurance Welfare Foundation     

Recovery Off-Kinetics Following Exhaustive Upper Body Exercise in Spinal Cord Injury

Background:People with spinal cord injury (SCI) present with impaired autonomic control when the lesion is above T6. This could lead to delayed cardiorespiratory recovery following vigorous physical activity.Objectives:To characterize and compare gas exchange off-kinetics following exhaustive exercise in individuals with SCI and an apparently healthy control group.Methods:Participants were 19 individuals with SCI who presented with the inability to voluntarily lift their legs against gravity (age, 44.6 ± 14.2 years; AIS A, n = 5; AIS B, n = 7; AIS C, n = 7; paraplegia, n = 14; tetraplegia, n = 5) and 10 healthy comparisons (COM; age, 30.5 ± 5.3 years). All participants performed an arm ergometer cardiopulmonary exercise test (aCPET) to volitional exhaustion followed by a 10-minute passive recovery. O₂ uptake (V̇o₂) and CO₂ output (V̇co₂) off-kinetics was examined using a mono-exponential model in which tau off (τ_off) and mean response time (MRT) were determined. The off-kinetics transition constant (Kt_off) was calculated as ΔV̇o₂/MRT. Student t tests were used to compare SCI versus COM group means.Results:COM had a significantly higher relative peak V̇o₂ compared to SCI (1.70 ± 0.55 L/min vs 1.19 ± 0.51 L/min, p = .019). No difference was observed for τ_off between the groups, however Kt_off for both V̇o₂ and V̇co₂ was significantly lower in the SCI compared to the COM group.Conclusion:A reduced Kt_off during recovery may suggest inefficiencies in replenishing muscle ATP stores and lactate clearance in these participants with SCI. These findings may contribute to the observed lower cardiorespiratory fitness and greater fatigability typically reported in individuals with SCI.     

Treadmill exercise testing with increasing inclination as exercise protocol for wheelchair athletes.

STUDY DESIGN: Treadmill testing on a progressive incline of 11 wheelchair athletes. OBJECTIVE: To determine if a novel treadmill exercise protocol which uses increments in inclination, rather than the standard increments in velocity, can be used to effectively determine maximum oxygen uptake VO2max for elite wheelchair athletes. SETTING: Nottwil, Switzerland. METHODS: Eleven elite wheelchair basketball players (29.3+/-6.3 years, 72.7+/-16.9 kg and 177+/-9.6 cm) performed an exercise protocol with increasing inclination on the treadmill. Eight players had a spinal cord injury (SCI), two had no lesion of the central nervous system and one had poliomyelitis. VO2max and heart rate were measured continuously, while serum lactate was determined immediately after the exercise protocol. RESULTS: Athletes reached a maximal heart rate of 185+/-11.4 bpm and maximal lactate of 10.2+/-2.1 mmol/l. VO2max was 35.1+/-4.9 ml/min/kg. The correlation between heart rate and VO(2) at different inclinations was statistically significant and comparable to able-bodied subjects. CONCLUSIONS: An exercise protocol with increasing inclination is a valid alternative to an exercise protocol with increasing velocity.     

The influence of high-velocity resistance circuit training on aerobic power*

* This work was supported by the Natural Sciences and Engineering Research Council. This study was designed to investigate the influence of high-velocity resistance circuit training on maximal aerobic power. Twenty-seven trained males participated either as training (N = 16) or control (N = 11) subjects. The training group exercised for two 20 sec sets at each of six stations of hydraulic, variable resistance apparatus over two or three circuits maintaining an exercise:relief ratio of 1:2 during each circuit. Subjects trained four times weekly over 5 weeks. The resistance at each station was adjusted as necessary to maintain consistent angular limb velocities of approximately 3.2 rad/sec. The VO2max for the training group was increased (p < 0.001) by 9.5% when expressed in either absolute or relative terms. No changes were observed for control subjects. Oxygen consumption responses measured over two circuits for six training group subjects averaged 61 and 57% of VO2max for exercise and relief intervals, respectively. It is therefore suggested that the hydraulic circuit resistance program described will elicit a metabolic intensity sufficient to improve aerobic power, even in previously trained subjects.J Ortho Sports Phys Ther 1988;9(10):339-344.     

Effect of exercise at the AT point for children with cerebral palsy

Eleven children with spastic cerebral palsy (CP) who could walk underwent exercise at the anaerobic threshold (AT) point. The subjects exercised for 20 minutes per session, twice a week for a period ranging from 6 to 20 weeks. The subjects were divided into two groups. The leg exercise group contained six CP children who exercised on a cycle ergometer with average attendance of 1.8 days a week. The other five CP children constituted the arm exercise group and exercised using an arm cranking ergometer with average attendance of 1.5 days per week. After the exercise period, the oxygen uptake (VO2) at the AT point increased significantly in the children in the leg exercise group. On the other hand, the VO2 at the AT point did not change in children in the arm exercise group. These results demonstrate that cycle ergometer exercise at the AT point is effective in improving the physical endurance of children with CP. In contrast, arm exercises for children with CP seem to have little effect on increasing physical endurance.     

Exercise training for claudicants: changes in blood flow, cardiorespiratory status, metabolic functions, blood rheology and lipid profile.

OBJECTIVE: Exercise training improves the walking distance of claudicants. The aim of this study was to investigate factors associated with the improvement in the maximum walking distance (MWD) in respect to cardiovascular, respiratory and metabolic adaptations. METHODS: Forty claudicants were studied. Common femoral artery blood flow (BF), heart rate (HR), oxygen consumption (VO(2)), respiratory exchange ratio (RER), lactate levels, blood rheology and lipid profiles were measured. Tests were repeated after 3 months of exercise training. RESULTS: Fifteen patients did not complete the exercise program. For patients who did complete the program, MWD improved by 82%. A significant reduction in HR and VO(2)during exercise was demonstrated. No significant changes occurred in BF or RER. Although MWD increased significantly, there was no increase in recovery VO(2)(oxygen debt). A significant reduction in post-exercise lactate levels occurred. Blood rheology was unchanged, but an improvement in HDL levels was noted. CONCLUSIONS: Many claudicants could not complete an exercise program, mainly due to osteoarthritis. Exercise training improved exercise tolerance significantly without any increase in BF. The HR and oxygen cost of similar exercise was reduced. An improved MWD did not correlate with a higher oxygen debt or lactate load. Favourable changes in lipid profiles occurred.     

Fat oxidation at different intensities in wheelchair racing

STUDY DESIGN: Determination of fat oxidation at three different intensities in trained wheelchair athletes on the treadmill. OBJECTIVE: The aim of the study was to assess the level and highest rate of fat oxidation in endurance-trained wheelchair athletes for recommendation on endurance training. SETTING: Institute of Sports Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland. METHODS: Nine (seven men and two women) endurance-trained wheelchair athletes (VO(2peak) 40.2+/-6.7 ml/kg/min) were studied over 20 min at 55, 65 and 75% VO(2peak) on a treadmill in their own racing wheelchairs in order to find the exercise intensity with the highest absolute fat oxidation. RESULTS: As presumed, total energy expenditure for wheelchair racing was highest at 75% VO(2peak), while absolute fat oxidation was statistically not significantly different at the three tested intensities. Percentage of energy expenditure from fat oxidation decreased with increasing intensity from 31.4% at 55% VO(2peak) to 20.9% at 75% VO(2peak), while percentage from carbohydrate oxidation increased from 68.6% at 55% VO(2peak) to 79.1% at 75% VO(2peak). CONCLUSION: For wheelchair athletes, we recommend training of fat metabolism for endurance exercise at an intensity of 55% VO(2peak), because absolute fat metabolism is not higher at higher intensities but less carbohydrates are used at lower intensity levels. At lower intensities, exercise can be performed over a longer time before the emptied glycogen stores will limit exercise duration. This may apply especially to paraplegic subjects whose active muscle mass is limited in contrast to able-bodied athletes.     

Submaximal physical strain and peak performance in handcycling versus handrim wheelchair propulsion

STUDY DESIGN: Experimental study in subjects with paraplegia and nondisabled subjects. OBJECTIVE: To compare submaximal physical strain and peak performance in handcycling and handrim wheelchair propulsion in wheelchair-dependent and nondisabled control subjects SETTING: Amsterdam, The Netherlands. METHODS: Nine male subjects with paraplegia and 10 nondisabled male subjects performed two exercise tests on a motor-driven treadmill using a handrim wheelchair and attach-unit handcycle system. The exercise protocol consisted of two 4-min submaximal exercise bouts at 25 and 35 W, followed by 1-min exercise bouts with increasing power output until exhaustion. RESULTS: Analysis of variance for repeated measures showed a significantly lower oxygen uptake (VO2), ventilation (Ve), heart rate (HR), rate of perceived exertion and a higher gross efficiency for handcycling at 35 W in both subject groups, while no significant differences were found at 25 W. Peak power output and peak VO2, Ve and HR were significantly higher during handcycling in both groups. The differences between handcycling and wheelchair propulsion were the same in subjects with paraplegia and the nondisabled subjects. CONCLUSIONS: Handcycling induces significantly less strain at a moderate submaximal level of 35 W, and shows noticeably higher maximal exercise responses than wheelchair propulsion, which is consistent in subjects with paraplegia and nondisabled controls. These results demonstrate that handcycling is beneficial for mobility in daily life of wheelchair users.     

Intermittent claudication: exercise-increased walking distance is not related to improved cardiopulmonary fitness.

OBJECTIVES: To assess if exercise training improves the symptoms of intermittent claudication by improvement in cardiopulmonary fitness. METHODS: Claudication distance (CD), maximum walking distance (MWD), calf endurance (repetitive heel raises), cardiovascular fitness (VO2 peak), and ankle-brachial pressure index (ABPI) were measured in 16 subjects with intermittent claudication before, and following an 8-week treadmill training programme. RESULTS: Training resulted in a median increase in CD of 65.5 m (p<0.01), MWD of 339.5 m (p<0.001) and HR of 19 (p<0.03). Notably, improvements in MWD correlated with those in HR (p=0.001; R=0.75). There was no training-associated change in VO2 peak (median increase of only 0.35 ml/kg/min; p=0.60) or ABPI (median increase of only 0.01; p=0.64). CONCLUSION: In this study, overall improvement in claudication was not related to an improvement in cardiopulmonary fitness.     

The incidence of post-race symptoms of upper respiratory tract infection in wheelchair marathon racers

STUDY DESIGN: Prospective analysis. OBJECTIVES: To investigate the influence of exercise and major competition on infectious episodes in athletes with spinal cord injuries (SCI). SETTING: Japan. METHODS: We examined the self-reported infectious episodes of upper respiratory tract infection (URTI) in athletes with SCI during a 1-month period before the race and 2 weeks after the race. The study included 21 persons with SCI who participated in the 18th Oita International Wheelchair Marathon. Thirteen persons with SCI who did not participate in the race were studied as control subjects. RESULTS: The number of URTI episodes in marathoners was 0.086+/-0.036/week during the 1-month period before the race and 0.089+/-0.040/week during the 2-week post-race period, whereas that of the controls was 0.139+/-0.046/week during the 1-month period before the race and 0.072+/-0.047/week during the 2-week post-race period. There were no significant differences between before and after the race in marathoners, or between marathoners and controls during each period. However, the number of URTI episodes 2 weeks after the race was significantly higher in subjects who trained more than 65 km/week compared to those who trained less than 65 km/week. CONCLUSIONS: In subjects with SCI who completed a wheelchair full marathon race, the incidence of URTI after the race was not high compared to control subjects who did not participate in the race. According to the number of URTI episodes and the training data, it is recommended that wheelchair marathoners should consider their risk for URTI during excessive practice.     

Biological quality control for exercise testing

BACKGROUND: A study was undertaken to evaluate the use of a biological quality control programme for a computer controlled, breath-by-breath exercise test system over a 2.5 year period. METHODS: One healthy volunteer performed a regular progressive treadmill test with breath-by-breath measurements of oxygen uptake (VO(2)), carbon dioxide output (VCO(2)), ventilation (VE), and the ECG heart rate (HR). Following a familiarisation period, five consecutive tests were performed and the measurements at peak exercise were averaged to give baseline values. All tests were compared with these values. RESULTS: A total of 35 tests were recorded. The within subject standard deviation for measurements at peak exercise were 52 ml/min for VO(2), 74 ml/min for VCO(2), 3.1 l/min for VE, and 3 beats/min for HR. The mean (SE) percentage variation in measurements at peak exercise compared with the baseline values was +0.37 (0.30)% for VO(2), -0.10 (0.39)% for VCO(2), -0.88 (0.52)% for VE, and +1.2 (0.26)% for HR. The variability present in measurements made during high and moderate intensity exercise (73% VO(2)peak) was not significantly different (p>0.05). During the study period the quality control detected a fault on the oxygen analyser which was not apparent from the automatic calibration. CONCLUSIONS: Regular quality control using a healthy volunteer allows all components of the breath-by-breath system to be checked simultaneously and in a manner which is consistent with its clinical use. This practice can highlight faults not detected by automatic calibration.     

Exercise performance increases coincident to body weight over the first two years following cardiac transplantation

Chaudry H, Yip DS, Bush T, Reynolds V, Witzke L, Taylor V, Hosenpud JD. Exercise performance increases coincident to body weight over the first two years following cardiac transplantation.
Clin Transplant 2011: 25: 685–688. © 2011 John Wiley & Sons A/S. Abstract: Background: To determine whether exercise performance changed over time once patients stabilized after heart transplantation, metabolic stress testing was performed in patients one and two yr post‐heart transplantation. Methods: The patient cohort includes those transplanted in our program who survived at least two yr and were able to perform metabolic stress tests during their one‐ and two‐yr annual evaluations. Standard stress test parameters were assessed, including weight, body surface area, rest and exercise heart rate (HR) and blood pressure (BP), exercise time, anaerobic threshold (AT), and maximum VO2 (MVO2). Ejection fraction by echo was also collected. Each patient served as their own control and data were compared using paired t‐testing. Results: Fifty patients were included in the cohort, 48 of whom were able to exercise to at least AT. Patient weight increased from year 1 to year 2 (82.4 ± 15.1 vs. 85.0 ± 17.0 kg, p = 0.035). Systolic BP increased approximately 40 mmHg with exercise with no change in diastolic BP, and there was no difference between years 1 and 2. HR increased approximately 25 bpm with exercise. There was no difference in resting HR but exercise HR increased significantly between yrs (148 ± 15 bpm vs. 154 ± 18 bpm, p = 0.017). Both VO2 at AT and MVO2 increased significantly from year 1 to year 2 (1116 ± 347 mL/min vs. 1192 ± 313 mL/min, p = 0.049 and 1523 ± 337 mL/min vs. 1599 ± 356 mL/min, p = 0.012, respectively) but when corrected for body weight, there were no differences (VO2‐AT 13.6 ± 4.0 mL/kg/min vs. 14.0 ± 4.0 mL/kg/min; MVO2 18.7 ± 4.2 mL/kg/min vs. 18.8 ± 4.1 mL/kg/min). All other measured parameters were not different. There was a weak but statistically significant correlation between change in peak HR and change in VO2 at AT between one and two yr post‐transplantation (r = 0.30, p = 0.04). Conclusions: We conclude that exercise performance as measured by VO2 can increase over time post‐heart transplantation and in our cohort appears to be related to both an increase in body weight and an increase in HR from years 1 and 2.