Changes in oxygen uptake, shoulder muscles activity, and propulsion cycle timing during strenuous wheelchair exercise

STUDY DESIGN: Cross-over study. OBJECTIVE: To determine the effect of strenuous wheelchair exercise on oxygen uptake (VO2 ), muscle activity and propulsion cycle timing (including the push time and recovery time during one full arm cycle). SETTING: Laboratory of Sport Sciences at the University of France-Comte in France. METHODS: Two exercise bouts of 6-min duration were performed at a constant workload: (1) non-fatigable exercise (moderate workload) and (2) fatigable exercise (heavy workload). Measurement of VO2, surface electromyographic activity (EMG) from shoulder muscles, and temporal parameters of wheelchair ergometer propulsion were collected from eight able-bodied men (26+/-4 years). RESULTS: A progressive increase in VO2 associated with EMG alterations (P<0.05), and a decrease of the cycle and recovery time (P<0.05) during the heavy exercise. Whereas the push time remained constant, an increased muscle activation time (P<0.05) was found during heavy exercise. CONCLUSION: Observations during wheelchair ergometry indicate the development of fatigue and inefficient muscle coordination, which may contribute to deleterious stress distributions at the shoulder joint, increasing susceptibility to injury.     

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.     

Kinetic factors determining wheelchair propulsion in marathon racers with paraplegia.

OBJECTIVE: To assess the different factors that determine the propulsion of wheelchair in long distance racers with spinal cord injuries. DESIGN AND METHODS: Nine highly handicapped men who competed at the Oita International Wheelchair Marathon in 1995, participated in this study. Subjects performed steady and exhaustive wheelchair propulsion at their optimal speed on wheelchair rollers in a laboratory setting during a 5-min period. Movements of the trunk and arms were filmed by a video camera then analyzed kinetically using a two-dimensional analysis system. In order to determine the actual pushing time and angle of wheelchair, we measured the duration between hand contact and hand release from handrim. SETTING: Department of Rehabilitation Medicine University of Occupational and Environmental Health, Japan. RESULTS: The push time, cycle time, total push time, and angular velocity did not relate with the race time or wheelchair velocity. However, the total push angle correlated significantly (P<0.01) with the race time and wheelchair velocity. Improvement of the pushing angular velocity and pushing duration did not contribute to the race time. CONCLUSION: The skilful wheelchair propulsion in long distance racing depends on the total push angle. Improvement of the total push angle should be achieved by both prolongation of the total push time and increased pushing angular velocity.     

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).     

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.     

The effectiveness of community-based upper body exercise programs in persons with chronic paraplegia and manual wheelchair users: A systematic review

Context: Physical activity has been beneficial to health, functional independence and quality of life in individuals with spinal cord injury. However, there is no consensus concerning the effects of community-based upper-body exercise for people with paraplegia who use a manual wheelchair.Objective: Conduct a systematic review of evidence of upper-body exercise effects able to be developed in a community-setting, on both functional independence and quality of life, for individuals with chronic paraplegia who use a manual wheelchair.Methods: PubMed, Scopus, Ebsco, SportDiscus and Web of Science databases were browsed, searching for studies that combined words as paraplegia, exercise, functional independence and quality of life and their synonyms, published from January/1998 to December/2018 in English. PEDro scale and the Cochrane tool analyzed methodological quality and risk of bias, respectively.Results: Four studies were selected out of 4004. Studies conducted aerobic arm-ergometer and resistance training predominantly at home. Upper-limb functionality and wheelchair propulsion assessed functional independence, but only the first presented positive effects after resistance training. Resistance and aerobic arm-ergometer training seemed to improve health-related and subjective quality of life.Conclusion: Studies have shown low methodological quality and high risk of bias. Aerobic arm-ergometer and resistance training were the most upper-body exercises used. Resistance training improved functional independence while both types of exercise induced positive effects on quality of life. Future studies with uniform and high-quality methodology should be conducted with exercise in community-dwelling people with paraplegia who use a manual wheelchair.     

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.     

Metabolic rate and cardiorespiratory response during hybrid cycling versus handcycling at equal subjective exercise intensity levels in people with spinal cord injury

Abstract

Objective

To compare the metabolic rate and cardiorespiratory response during hybrid cycling versus handcycling at equal subjective exercise intensity levels in people with spinal cord injury (SCI).

Design

Cross-sectional study.

Setting

Amsterdam Rehabilitation Research Centre | Reade, Amsterdam, The Netherlands.

Methods

On separate days, nine individuals with a motor complete paraplegia or tetraplegia (eight men, age 40 ± 13 years, time since injury 12 ± 10 years) performed 5-minute bouts of hybrid cycling (day 1) and handcycling (day 2) at moderate (level 3 on a 10-point rating of perceived exertion (RPE) scale) and vigorous (RPE level 6) subjective exercise intensity, while respiratory gas exchange was measured by open-circuit spirometry and heart rate was monitored using radiotelemetry.

Outcome measures

Metabolic rate (calculated with the Weir equation) and cardiorespiratory response (heart rate, oxygen pulse, and ventilation).

Results

Overall, the metabolic rate during hybrid cycling was 3.4 kJ (16%) higher (P = 0.006) than during handcycling. Furthermore, compared with handcycling, the overall heart rate and ventilation during hybrid cycling was 11 bpm (11%) and 5.3 l/minute (18%) higher (P = 0.004 and 0.024), respectively, while the oxygen pulse was the same (P = 0.26).

Conclusion

Hybrid cycling induces a higher metabolic rate and cardiorespiratory response at equal RPE levels than handcycling, suggesting that hybrid cycling is more suitable for fighting obesity and increasing cardiorespiratory fitness in individuals with SCI.     

Evidence for an exaggerated postprandial lipemia in chronic paraplegia

BACKGROUND/OBJECTIVE: Excessive delay in triglyceride (TG) metabolism after ingestion of dietary fat represents a significant cardiovascular disease (CVD) risk. The objective of this study was to compare the postprandial lipemic responses of individuals with paraplegia with those of healthy nondisabled individuals. METHODS: The ability of 3 recreationally active individuals with paraplegia having normal fasting TG (mean = 103 mg/dL) to metabolize TG after ingestion of a high-fat test meal was compared with a previously published cohort of 21 recreationally active individuals without paraplegia (TG mean = 86 mg/dL) who underwent identical testing. The subjects with paraplegia had venous blood taken under fasting conditions, and then ingested a milkshake containing premium ice cream blended with heavy whipping cream (approximately 92% of calories from fat). Additional blood samples were obtained at 2, 4, and 6 hours after ingestion. The area under the curve (AUC) for TG clearance for both subject groups was measured with an area planimeter. RESULTS: TG uptake for both groups was almost identical for the first 2 hours after ingestion. At 4 and 6 hours after ingestion, the TG levels were 50 and 35 mg/dL higher, respectively, in subjects with paraplegia than in nondisabled subjects. When corrected for small baseline differences in TG concentrations (16 mg/dL), the AUC was 46.5% greater for the group with paraplegia than in the nondisabled group. A near mirror association across time was observed between postprandial serum high-density lipoprotein cholesterol (HDL-C) and TG levels in subjects with paraplegia. CONCLUSION: This case series finds an exaggerated postprandial lipemia (PPL) in persons with paraplegia with normal fasting TGs. This finding is the first evidence, in a small population, of an unreported potential CVD risk in persons with paraplegia.     

Development and evaluation of a gyroscope-based wheel rotation monitor for manual wheelchair users

Abstract

Objective

To develop and evaluate a wireless gyroscope-based wheel rotation monitor (G-WRM) that can estimate speeds and distances traveled by wheelchair users during regular wheelchair propulsion as well as wheelchair sports such as handcycling, and provide users with real-time feedback through a smartphone application.

Methods

The speeds and the distances estimated by the G-WRM were compared with the criterion measures by calculating absolute difference, mean difference, and percentage errors during a series of laboratory-based tests. Intraclass correlations (ICC) and the Bland–Altman plots were also used to assess the agreements between the G-WRM and the criterion measures. In addition, battery life and wireless data transmission tests under a number of usage conditions were performed.

Results

The percentage errors for the angular velocities, speeds, and distances obtained from three prototype G-WRMs were less than 3% for all the test trials. The high ICC values (ICC (3,1) > 0.94) and the Bland–Altman plots indicate excellent agreement between the estimated speeds and distances by the G-WRMs and the criterion measures. The battery life tests showed that the device could last for 35 hours in wireless mode and 139 hours in secure digital card mode. The wireless data transmission tests indicated less than 0.3% of data loss.

Conclusion

The results indicate that the G-WRM is an appropriate tool for tracking a spectrum of wheelchair-related activities from regular wheelchair propulsion to wheelchair sports such as handcycling. The real-time feedback provided by the G-WRM can help wheelchair users self-monitor their everyday activities.     

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.     

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.     

Effectiveness of an upper extremity exercise device integrated with computer gaming for aerobic training in adolescents with spinal cord dysfunction

BACKGROUND/OBJECTIVE: To determine whether a new upper extremity exercise device integrated with a video game (GameCycle) requires sufficient metabolic demand and effort to induce an aerobic training effect and to explore the feasibility of using this system as an exercise modality in an exercise intervention. DESIGN: Pre-post intervention. SETTING: University-based research facility. SUBJECT POPULATION: A referred sample of 8 adolescent subjects with spina bifida (4 girls, 15.5 +/- 0.6 years; 4 boys, 17.5 +/- 0.9 years) was recruited to participate in the project. All subjects had some level of mobility impairment that did not allow them to participate in mainstream sports available to their nondisabled peers. Five subjects used a wheelchair full time, one used a wheelchair occasionally, but walked with forearm crutches, and 2 were fully ambulatory, but had impaired gait. MAIN OUTCOME MEASURES: Peak oxygen uptake, maximum work output, aerobic endurance, peak heart rate, rating of perceived exertion, and user satisfaction. RESULTS: Six of the 8 subjects were able to reach a Vo2 of at least 50% of their Vo2 reserve while using the GameCycle. Seven of the 8 subjects reached a heart rate of at least 50% of their heart rate reserve. One subject did not reach either 50% of Vo2 reserve or 50% of heart rate reserve. Seven of the 8 subjects increased their maximum work capability after training with the GameCycle at least 3 times per week for 16 weeks. Conclusions: The data suggest that the GameCycle seems to be adequate as an exercise device to improve oxygen uptake and maximum work capability in adolescents with lower extremity disability caused by spinal cord dysfunction. The subjects in this study reported that the video game component was enjoyable and provided a motivation to exercise.     

Exercise responses in patients treated for pulmonary tuberculosis by thoracoplasty.

Twenty eight subjects (mean age 64 years) who had been treated for tuberculosis by thoracoplasty in the past performed an increasing work rate exercise test, from which maximum oxygen consumption (VO2max), ventilation and heart rate were measured. VO2max was significantly lower than predicted, being 0.75 l/min in 17 subjects, 1.0 l/min in 10, and 1.5 l/min in one. Only one subject achieved a heart rate of 85% of the predicted maximum. The ratio of heart rate to oxygen consumption (HR/VO2) and heart rate at standard interpolated submaximal levels of oxygen uptake at 0.75 l/min (heart rate 0.75) and 1.0 l/min (heart rate 1.0) were normal. VO2max correlated with ventilation at maximal exercise (VE max) (r = 0.87) and FEV1 (r = 0.47). It did not correlate with resting arterial oxygen or carbon dioxide tensions, FEV1, maximum inspiratory pressure, angle of scoliosis, or number of ribs resected. The relation between ventilation and oxygen consumption (VE/VO2) and VE at the submaximal levels of oxygen consumption of 0.75 l/min (VE 0.75) and 1.0 l/min (VE 1.0) were normal. In 10 subjects a plateau of breathing frequency (fmax) was reached, after which the increase in ventilation was achieved by a further increase in tidal volume (VT). These subjects showed significantly lower values for the forced expiratory ratio, VO2max, and VEmax than those with a normal relation between tidal volume and breathing frequency. VEmax was correlated with FEV1 (r = 0.61), FVC (r = 0.46), maximum VT (r = 0.55), change in VT (r = 0.52), fmax (r = 0.56), and change in breathing frequency (r = 0.72). These results indicate that exercise in patients treated for tuberculosis by thoracoplasty is limited by ventilatory capacity and that this is due to a reduction in both dynamic lung volumes and respiratory frequency.     

Nitric oxide synthase inhibition reduces glucose uptake during exercise in individuals with type 2 diabetes more than in control subjects

Nitric oxide (NO) synthase inhibition reduces leg glucose uptake during cycling without reducing leg blood flow (LBF) in young, healthy individuals. This study sought to determine the role of NO in glucose uptake during exercise in individuals with type 2 diabetes. Nine men with type 2 diabetes and nine control subjects matched for age, sex, peak pulmonary oxygen uptake (VO(2) peak), and weight completed two 25-min bouts of cycling exercise at 60 +/- 2% VO(2) peak, separated by 90 min. N(G)-monomethyl-L-arginine (L-NMMA) (total dose 6 mg/kg) or placebo was administered into the femoral artery for the final 15 min of exercise in a counterbalanced, blinded, crossover design. LBF was measured by thermodilution in the femoral vein, and leg glucose uptake was calculated as the product of LBF and femoral arteriovenous glucose difference. During exercise with placebo, glucose uptake was not different between control subjects and individuals with diabetes; however, LBF was lower and arterial plasma glucose and insulin levels were higher in individuals with diabetes. L-NMMA had no effect on LBF or arterial plasma glucose and insulin concentrations during exercise in both groups. L-NMMA significantly reduced leg glucose uptake in both groups, with a significantly greater reduction (P = 0.04) in the diabetic group (75 +/- 13%, 5 min after L-NMMA) compared with the control group (34 +/- 14%, 5 min after L-NMMA). These data suggest a greater reliance on NO for glucose uptake during exercise in individuals with type 2 diabetes compared with control subjects.     

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.     

Influence of lesion level on the cardioventilatory adaptations in paraplegic wheelchair athletes during muscular exercise

OBJECTIVES: To characterize the influence of neurological lesion level on the cardiorespiratory and ventilatory responses of two groups of paraplegic athletes during incremental exercise on a treadmill and in the usual conditions for wheelchair exercise. METHODS: Cardioventilatory responses evaluated in two groups of paraplegic wheelchair sportsmen designated as high paraplegic athletes (HPA) and low paraplegic athletes (LPA). After 2 min of data collection at rest and 3 min of warm-up at 4 km x h(-1), treadmill speed was increased by 1 km x h(-1) every minute until exhaustion. During this test, ventilation and its components, as well as respiratory exchanges, were measured breath by breath (C.P.X. Medical Graphics) every minute by taking the mean of the last 20 s of each increment. RESULTS: Spirometric values presented no significant differences between groups. At rest, no significant difference was observed between the two groups for all cardiorespiratory and ventilatory values obtained during the treadmill test. At submaximal exercise, all variables increased with the augmentation in workload. With the exception of R, there were no significant differences in the classic cardiorespiratory parameters (VO2, VCO2, HR, VE) between the two groups of paraplegics. For the ventilatory parameters, we observed significant differences between the two groups, with values of f and It/Trf significantly higher (0.01相似文献   

Handrim forces during wheelies performance in able-bodied and SCI subjects

Context: Manual wheelchair users must be able to carry out wheelies in order to tackle obstacles in the outdoor environment. To date, no studies have compared balance variables and forces exerted on the handrim during a stationary wheelie between able bodied and spinal cord injury subjects.Objectives: To compare the distribution of forces applied to the handrim and the center of pressure displacement during a stationary wheelie between able-bodied (AB) subjects and manual wheelchair users with spinal cord injury (SCI).Design: Prospective experimental study.Setting: A university hospital laboratory.Participants: 27 participants (14 AB and 13 SCI).Outcome Measure: Each participant performed 3 stationary wheelies of 60 s duration using a wheelchair equipped with an instrumented wheel. Two force platforms were used to calculate the displacement of the center of pressure (DCOP).Results: Median group DCOP amplitude in the anteroposterior axis was smaller and less variable in the AB (19.6 mm [8.1,49.6]) than the SCI (14.9 mm [7.6,141.1]) group. Forces applied to the handrim only differed significantly between the AB (6 N [−13.8,16.6]) and SCI groups (2.7 N [−12.1 21.9]) in the posteroanterior axis.Conclusions: The results showed that the participants with SCI exerted greater PA forces on the handrim, moreover, the direction of force was opposite to that of the AB group, suggesting that the SCI group used a proactive balance strategy while the AB group used a retroactive strategy. The results suggest that the direction of force applied should be considered when teaching individuals to perform wheelies.     

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.