Maximal exercise response of paraplegic wheelchair road racers.

The maximal metabolic responses of 11 paraplegic wheelchair road racers were evaluated with 2 wheelchair exercise protocols: increasing speed and increasing resistance. The maximal heart rates, minute ventilations and oxygen uptakes were similar for the 2 tests, indicating that either protocol is suitable for maximal wheelchair dynamometer exercise tests for groups. The resulting data were then compared to published data on maximal arm exercise by athletic and non athletic paraplegics and ambulatory males of the same age group. The combined mean values for both exercise tests of maximal oxygen consumption rate (VO2max = 37.4 ml/kg/min), minute ventilation (VE = 109.4 l/min), respiratory exchange quotient (RQmax = 1.18) and heart rate (187 beats/min) are in the mid range of reported data on wheelchair athletes. The mean RQ and heart rate values were similar to those achieved by ambulatory individuals performing maximal exercise tests. The mean VO2max of 37.4 ml/kg/min in our subjects is comparable to that achieved by sedentary ambulatory males of this age group. The data and the comparison to published data suggest several conclusions: in some parameters elite male paraplegic road racers have maximal values similar to those of ambulatory males, and in others they have maximal values substantially lower than might be expected; there is considerable variability among paraplegics in the metabolic responses to maximal exercise, most likely related to differences in cardiovascular fitness; and paraplegics can improve their cardiovascular fitness by training.     

The effects of an arm ergometer training programme on wheelchair subjects

The purpose of the present investigation was to study the effects of an arm ergometer training programme on several physiological variables of recreational wheelchair subjects. Ten paraplegics (5 experimental, 5 control) were tested prior to and immediately after a 2 month exercise regimen at 80% of peak heart rate (30 min per day, 5 days per week, for 8 consecutive weeks at 50 rev/min). The results demonstrated significant increases (P less than 0.05) in VO2max (1 min-1 & ml kg-1 min-1) and workload but only mild improvements in maximal heart rate and post exercise blood lactates. Body fat, vital capacity and forced expiratory volume did not change with training. Triceps lateralis fibre distribution and fast twitch (FT) fibre area were unaffected by the endurance training programme. However, slow twitch (ST) fibre area increased (P less than 0.05) with training. The results indicate that physiological variables of paraplegic subjects following an arm ergometer endurance training programme react similarly to changes previously observed in non-handicapped subjects. The values when compared with normals are low as a result of the relative inactivity of the subjects due to the lack of available exercise programmes for wheelchair people.     

Exercise capacity of untrained spinal cord injured individuals and the relationship of peak oxygen uptake to level of injury

Twenty spinal cord injured individuals were tested for maximal oxygen uptake (VO2 peak using a hysteresis brake wheelchair ergometer. The subjects were divided into 4 groups as follows: (a) quadriplegics (4 subjects); (b) untrained female paraplegics (5 subjects); (c) untrained male paraplegics (7 subjects); and (d) trained male paraplegics (4 subjects). The VO2 peak were analysed by a one way ANOVA and Fisher's LSD multiple comparisons. The F-ratio (50.93) was significant (p = less than 0.0001). Fisher's LSD post hoc multiple comparisons found the following differences: (a) quadriplegics were significantly lower than the untrained paraplegic females, untrained paraplegic males and trained paraplegic males; (b) untrained females were significantly lower than the untrained male paraplegics, and trained paraplegic males; (c) untrained paraplegic males were significantly lower than the trained male paraplegics. A Spearman Rho correlation was calculated using injury level and VO2 max for all the untrained SCI individuals. The correlation was 0.68 and had a significance level of 0.0019. The present study combined with the known research literature gives strong evidence that VO2 peak in the untrained SCI is highly related to level of injury.     

Arm crank versus wheelchair treadmill ergometry to evaluate the performance of paraplegics

The purpose of this investigation was to compare peak performance capabilities of male paraplegics with arm crank and wheelchair ergometry. Eleven male paraplegics (aged 26.0 +/- 4.5 year) with spinal lesions at levels ranging from T5 to L4 were assessed during arm cranking and while propelling a wheelchair on a treadmill. Subjects completed both tests in randomised order within a 1 week period with a minimum of 48 hours between tests. Based on the data analysis, peak VO2 for the treadmill and arm crank were not significantly different while HR values for the treadmill were significantly greater (P less than 0.05) when compared to arm crank. A regression analysis indicated that wheelchair treadmill peak VO2 values can be accurately predicted from arm crank peak VO2 (r = 0.74).     

Aerobic power of competitive paraplegic road racers.

The purpose of this study was to determine peak aerobic power and associated physiological responses in highly competitive spinal cord injured (SCI) paraplegic road racers. Seven (6 male and one female) active paraplegic (lesions T4-T12) road racers and 9 healthy untrained able-bodied males performed continuous graded arm crank ergometer tests to exhaustion for determinations of peak power output (PO), oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), and respiratory exchange ratio (RER). Compared to able-bodied subjects, male paraplegic road racers elicited significantly (p less than or equal to .05) higher mean (+/- SD) peak levels of PO (141.6 +/- 8.8 vs 111.4 +/- 27.7 W), absolute VO2 (2.72 +/- .52 vs 2.22 +/- .381/min), and VO2 per unit of body weight (43.06 +/- 7.4 vs 30.33 +/- 4.3 ml/kg/min). Although peak HR (180.3 +/- 9.5 vs 173.2 +/- 8.5 bpm) and VE (92.8 +/- 17.2 vs 74.6 +/- 20.3 l/min) tended to be higher for male paraplegic road racers than able-bodied subjects, the differences were not statistically significant. The female paraplegic road racer achieved the highest peak levels of PO (119 W) and VO2 (1.99 l/min; 38.0 ml/kg/min) reported to date for wheelchair-dependent women. These data suggest that intense physical training via wheelchair propulsion can markedly enhance upper body cardiovascular fitness in SCI paraplegics. However, the correlational analysis between 10 km time and peak VO2 was nonsignificant (p greater than .05) indicating that factors other than peak upper body aerobic power may influence wheelchair road racing performance.     

Physical fitness of paraplegics in full wheelchair marathon racing

The wheelchair marathon is one of the most difficult sports for participants with much uncertainty regarding the security of the paraplegics. The physical fitness of paraplegics has been examined regularly since The Oita International Wheelchair Marathon (half marathon) was inaugurated (1981). A full marathon (42.195 km) was adopted at The 3rd Meeting (1983). The individual equations between heart rate (HR) and oxygen consumption VO2 were drawn from the preliminary test on the subjects who were expected to be among the top finishers in these races. VO2 during these races was indirectly estimated and showed a fairly low value (35.0 +/- 3.8 ml/kg/min in the full race, 32.7 +/- 6.3 ml/kg/min in the half race respectively) in comparison with able-bodied elite runners. However, the paraplegic participants had extremely high HR (171.6 +/- 20.5 beats/min, 168.1 +/- 9.8) continuously throughout the race. Though the ratio of active muscle mass of arms to legs in paraplegic athletes may approximate to near equal, paraplegic arms seem to exert physiologically and mechanically less efficient power. There were no significant differences in physical fitness between the full and the half marathon elite finishers. The cardiovascular function of paraplegic athletes may well be ranked among those of able-bodied athletes in their fitness. Full wheelchair marathon seems to be safe if it is held in an appropriate environment.     

Comparison of physiological responses to maximal arm exercise among able-bodied, paraplegics and quadriplegics

A comparison of pulmonary, cardiovascular and metabolic responses was made in 32 subjects consisting of 11 able-bodied, 8 paraplegics (T4-L3 lesions) and 13 quadriplegics (C5-C8 lesions) during maximal arm cranking exercise. A progressive continuous arm cranking test, modified for each group, was employed to elicit maximal responses with pulmonary and metabolic determinations made with open circuit spirometry and selected cardiovascular measurements made by impedance cardiography. Additionally, non-exercise static and dynamic lung function assessments were made. Quadriplegics had significantly lower (p less than 0.05) tidal volumes, vital capacities, forced expiratory volumes at 1 seconds, and maximal breathing capacities than the other two groups. The mean peak VO2 during maximal arm cranking was 28.2, 25.3 and 12.0 ml/kg.min for the able-bodied (AB), paraplegics (PP) and quadriplegics (QP), respectively. Furthermore, reduced cardiovascular function was observed in the QP as evident in the low peak HR (109 b/min), peak SV (52 ml/b) and peak Q (5.7 l/min). Values for the QP were 64% and 64% peak HR, 89% and 50% peak SV and 54% and 33% peak Q of values observed for the PP and AB groups, respectively. The peak SV and Q values were significantly lower (P less than 0.05) for the PP group when compared with the AB group. Although not statistically significant the estimated a-v O2 difference was higher for both spinal cord injured groups (14.0 and 14.6 ml O2/100 ml, PP and QP respectively). The impaired work capacity and reduced oxygen transport and utilisation of the QP group can be attributed to impaired sympathetic cardiac stimulation and a smaller available active muscle mass.     

An exercise test to evaluate fitness for wheelchair activity.

The purpose of this study was to develop a wheelchair ergometer (WERG) test to evaluate fitness for manual wheelchair activity. Thirty able-bodied females participated in a progressive intensity, discontinuous test where exercise bouts were 4 min in duration interspersed with 5-min rest periods. Physiological responses of oxygen uptake (VO2), respiratory exchange ratio (R), net mechanical efficiency (ME), pulmonary ventilation (VO) and heart rate (HR) were determined during the final minute of exercise at power output (PO) levels of 30, 60, 90, 120 and 150 kpm/min. These responses were generally found to be linearly related to PO, however, net ME initially increased with PO and plateaued at approximately 11 per cent at 90 kpm/min. Criteria for fitness evaluation were based upon: (1) magnitude of physiological responses at each PO level; and (2) the maximal PO level completed.     

Aerobic capacity in early paraplegia: implications for rehabilitation

Both strength (ability to develop tension) and endurance (aerobic capacity as measured by VO2 max) contribute to overall functional capacity. In the rehabilitation of individuals with major neuromuscular deficits such as paraplegia, primary emphasis is generally placed on strength training to develop functional independence. However, endurance training may also be important. To clarify the influence of paraplegia on the VO2, we studied 10 paraplegics between 2 to 12 weeks after injury to determine whether or not a deficit in arm VO2 max was present before the inception of a conventional rehabilitation programme, and whether it persisted in three subjects after its completion. Cardiorespiratory responses to progressive multi-stage arm ergometry were measured using standard open circuit calorimetry. Ten paraplegic subjects demonstrated a low VO2 max compared to control subjects. This deficit persisted when selected subjects (n = 3) were tested after completion of a conventional rehabilitation programme which emphasised strengthening exercises. Further research is needed to study the effects of complementary endurance training on the aerobic capacity as measured by VO2 max, and to assess their value in the rehabilitation process.     

Enhanced carotid-cardiac baroreflex response and elimination of orthostatic hypotension 24 hours after acute exercise in paraplegics.

To test the hypothesis that an acute bout of maximal exercise can ameliorate orthostatic hypotension consequent to prolonged wheelchair confinement, we evaluated heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure responses during 15 minutes of 70 degrees head-up tilt (HUT) in 10 paraplegic subjects 24 hours after arm crank exercise designed to elicit maximal effort, and during a control (no exercise) conditions. Additionally, the carotid baroreceptor stimulus-cardiac response relationship was determined by measurement of R-R interval during external application of graded pressures to the carotid sinuses. One week separated the treatment conditions. The maximum slope of the carotid-cardiac baroreflex response was increased (p = 0.049) by exercise (6.2 +/- 1.7 msec/mmHg) compared to control (3.3 +/- 0.6). During control HUT, HR increased from 61 +/- 1 to 90 +/- 7 bpm (p = 0.001) while SBP decreased from 118 +/- 5 to 106 +/- 9 mmHg (p = 0.025). During HUT 24 hours after exercise, HR increased from 60 +/- 2 to 90 +/- 4 bpm (p = 0.001), but the reduction in SBP was essentially eliminated (116 +/- 5 to 113 +/- 5 mmHg). The reduction in SBP during control HUT (-12.0 +/- 4.6 mmHg) was four-fold larger (p = 0.017) than during HUT following exercise (-3.1 +/- 3.9 mmHg). DBP during HUT was not altered in either condition. A single bout of intense, dynamic arm crank exercise eliminated orthostatic hypotension in paraplegics. Equal HR response with smaller reduction in SBP during HUT after exercise was consistent with a measured increased sensitivity of the carotid-cardiac baroreflex.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolic responses of women to exercise attributable to long term use of a manual wheelchair

The purpose of this study was to determine the effects of long term use of a manual wheelchair by wheelchair-confined women (means = 14.6 years) on physiological responses to wheelchair ergometry. Six experimental subjects were compared to six able bodied women during maximal exercise as well as submaximal wheelchair ergometry at 50 and 80% of peak VO2. The wheelchair dependent women achieved higher power outputs, greater efficiency at the higher submaximal workload, less metabolic acidosis during submaximal exercise as well as less ventilatory stress. There was no significant difference in peak VO2 between the two groups of women. Because these were not athletically trained women, it was concluded that the long term use of a manual wheelchair leads to physiological adaptations favourable to the daily requirements of wheelchair locomotion.     

The effects of arm cranking exercise and training on platelet aggregation in male spinal cord individuals

Platelet aggregation at rest and in responses to exercise and training were compared between spinal cord injured (SCI) individuals (N=5) and able-bodied subjects (N=7). All participants performed arm cranking exercise at 60-65% VO(2peak) for 30 min. Venous blood samples were obtained before and after sub-maximal exercise and measured for platelet aggregation using ADP and collagen. To assess the effects of arm cranking training, platelet aggregation was re-measured in all subjects at rest and in response to the sub-maximal arm cranking exercise after 12 weeks of individually supervised training programme. Before training, the resting mean values of platelet aggregation induced by ADP and collagen were not different (P>0.05) between SCI and able-bodied. However the SCI individuals, but not the able-bodied subjects, exhibited a significantly (P<0.05) higher maximal platelet aggregation induced by ADP and collagen following sub-maximal arm cranking exercise. Although VO(2peak) after training was significantly increased (P<0.05) in both groups, the resting mean values of platelet aggregation induced with ADP and collagen were not significantly different (P>0.05) from those observed before training and were not different (P>0.05) between SCI and able-bodied. Post-training, the SCI individuals, but not able-bodied individuals, exhibited a significant decrease (P<0.05) in platelet aggregation following sub-maximal arm cranking exercise and this occurred with both ADP and collagen. These results suggest that SCI individuals, but not normal subjects increase their platelet aggregation following sub-maximal arm cranking exercise. Furthermore, arm cranking training in SCI individuals, appears to diminish the percentage of platelet aggregation ex vivo.     

Transition of physical fitness in wheelchair marathon competitors over several years

Twenty eight stress tests for 14 wheelchair marathon competitors were performed to determine their physical fitness just before the Oita International wheelchair marathon since 1984. All the subjects were wheelchair-bound Japanese males and workers at Sun Industry. Oxygen consumption at the maximal workload was significantly larger than that of non-athletic paraplegics and the mean values were 35.0 +/- 4.8 ml/kg in competitors and 22.6 +/- 5.0 ml/min/kg in non-athletic paraplegics. Eight competitors had more than 2 stress tests and 6 of them had 3 tests from 1984 to 1987. The oxygen consumption at the maximal workload of their third test was very high (46.5 +/- 6.8 ml/min/kg) equal to highly trained paraplegics, and was larger than the result of the first test significantly. Their physical fitness was reduced significantly during the off season, however their physical fitness was maintained at a satisfactory higher level than that of non-athletes. This study demonstrated that individual training for wheelchair marathoners had improved the competitors' physical fitness over several years.     

A comparative study of the muscle strength and mass of the arm flexors and extensors in paraplegic and in non paraplegic basketball players.

OBJECTIVES: to study the changes in the strength of the elbow flexors and extensors in paraplegic subjects, and the agonist/antagonist mass and strength ratio in paraplegic wheelchair users. METHOD: 10 paraplegic wheelchair basketball players were compared with 10 healthy basketball players. The 20 subjects underwent a clinical and dynamometric isokinetic assessment, and a CT scan measurement of the muscle cross-sectional surface area of the flexor and extensor muscles of the elbows. RESULTS: there was an increase in muscle strength in paraplegic subjects. There was no significant difference in the agonist/antagonist ratio between the dominant and non dominant upper limb in paraplegics whereas such a difference was found in healthy subjects. The muscle mass was increased in the paraplegics, but a correlation between muscle mass and strength was only found in the healthy subjects.     

Free plasma catecholamines in spinal cord injured persons with different injury levels at rest and during exercise

Spinal cord lesion leads to an interruption of pathways from brain to the peripheral sympathetic nervous system, which results in pathological changes in sympathetic innervation. Free epinephrine (E), norepinephrine (NE) and dopamine (DA) were measured in 30 tetraplegics (TETRA), 15 high-lesion paraplegics (T₁ and T₄, HPARA), 15 paraplegics with injuries between T₅ and T₁₀ (MPARA), 15 low-lesion paraplegics (below T₁₀, LPARA) and 16 non-handicapped control persons (C) at rest, at 60 and 100% of maximal oxygen consumption during graded wheelchair ergometry (WCE). The TETRA showed significant lower E and NE levels at rest and only slight increases during physical exercise. The E and NE concentrations of the paraplegics with a lesion below T₅ were significantly higher than those of the high-lesion paraplegics, as well as those of the control persons at every point in the study. All paraplegics and the control persons showed, at submaximal and maximal exercise, a significant increase in NE. Only a slight increase in E in HAPRA was shown. No differences were found at rest and during exercise in E and NE levels in the MPARA and LPARA. No significant differences were found in the dopamine concentration at rest or during exercise for any of the groups. In summary, different levels of lesion and the resulting interruption to sympathetic pathways in the spinal cord are decisive factors in the degree of impairment of sympathetic innervation in SCI persons. Tetraplegics show less preganglionic resting activity because of interruption of impulses from central centers and no considerable stimulation of the sympathetic nervous system during maximal exercise. Individuals with high paraplegia have a partial impairment of catecholamine release, especially of epinephrine, at rest and during exercise. Paraplegics with a lesion level below T₅ showed an augmented basal and exercise-induced upper spinal thoracic sympathetic activity in comparison to control persons.     

Cycle ergometry is not a sensitive diagnostic test for mitochondrial myopathy

Cycle exercise has repeatedly been used to diagnose patients suspected of having mitochondrial myopathy (MM), in whom exercise intolerance and lactic acidosis are common. No standardized test, however, has been established. We evaluated the diagnostic value of incremental and constant workload (20 min at 65 % VO(2max)) cycle tests for the diagnosis of MM. Plasma lactate and oxidative capacity (VO(2) and workload) were measured in 15 well-characterized MM patients during cycling. Findings were compared with those in 10 myotonic dystrophy patients and 18 sedentary, healthy subjects.All MM patients had ragged red or COX-negative fibers on muscle biopsy. VO(2max) and maximal workload were lower in MM than in control groups (P < 0.02). Resting plasma lactate was higher in MM than in control groups (P < 0.005; sensitivity = 93 %; specificity = 85 %), while exercise-induced increases in plasma lactate were only higher during the constant workload protocol in MM patients vs. control groups (P < 0.05; sensitivity = 27 %; specificity = 86 %). The findings indicate that the diagnostic value of a constant workload protocol is superior to an incremental cycle test, but that the test is less sensitive for MM than simple testing of resting lactate and muscle morphology. Cycle testing of MM patients remains an important research tool, but should not be a standard diagnostic procedure for MM.     

Resting oxygen consumption and in vivo ADP are increased in myopathy due to complex I deficiency

BACKGROUND: Patients with isolated complex I deficiency (CID) in skeletal muscle mitochondria often present with exercise intolerance as their major clinical symptom. OBJECTIVE: To study the in vivo bioenergetics in patients with complex I deficiency in skeletal muscle mitochondria. METHODS: In vivo bioenergetics were studied in three of these patients by measuring oxygen uptake at rest and during maximal exercise, together with forearm ADP concentrations ([ADP]) at rest. Whole-body oxygen consumption at rest (VO(2)) was measured with respiratory calorimetry. Maximal oxygen uptake (VO(2)max) was measured during maximal exercise on a cycle ergometer. Resting [ADP] was estimated from in vivo (31)P MRS measurements of inorganic phosphate, phosphocreatine, and ATP content of forearm muscle. RESULTS: Resting VO(2) was significantly increased in all three patients: 128 +/- 14% (SD) of values in healthy control subjects. VO(2)max in patients was on average 2.8 times their VO(2) at rest and was only 28% of VO(2)max in control subjects. Resting [ADP] in forearm muscle was significantly increased compared with healthy control subjects (patients 26 +/- 2 microM, healthy controls 9 +/- 2 microM). CONCLUSION: In patients with CID, the increased whole-body oxygen consumption rate at rest reflects increased electron transport through the respiratory chain, driven by a decreased phosphorylation potential. The increased electron transport rate may compensate for the decreased efficiency of oxidative phosphorylation (phosphorylation potential).     

Fahrradfahren Querschnittgelähmter mittels funktioneller Elektrostimulation

Cycling using functional electrical stimulation offers paraplegics the possibility of muscle and cardiovascular training as well as the chance for independent locomotion. To investigate whether this method might be suitable for a large group of paraplegics, the first German feasibility study of functional electrical stimulation (FES) cycling with seven paraplegic patients was started at the beginning of 2003. Even at the beginning of the study, and without training, these patients were able to drive distances of 0.5-1.6 km. To stimulate cardiovascular adaptation processes in the case of FES ergometer training or to cover useful distances in the case of FES cycling, a minimum amount of generated mechanical output power is required, which as a rule cannot be achieved yet. In this study, we point out two particular aspects of FES cycling, which impair power output: prolonged fatigue mode and viscous joint friction of the paraplegic FES cyclist. We discuss current possibilities for increasing output power and endurance.     

Effects of heart-rate feedback on estimated cardiovascular fitness in patients with panic disorder

Psychological parameters that are believed to affect estimations of cardiovascular fitness were examined in patients with panic disorder and nonclinical controls. Fifty-four participants [panic disorder patients (n = 27) and age- and sex-matched nonclinical controls (n = 27)] completed a cycle ergometer test and were compared on the basis of estimated VO2 max. Participants were randomly assigned to experimental conditions in which they received heart-rate feedback or no feedback during the test. Patients with panic disorder exhibited lower VO2 max and decreased exercise tolerance (i.e., were more likely to discontinue the test) than nonclinical controls. Furthermore, individuals with high anxiety sensitivity (i.e., a fear of autonomic arousal), but not a panic disorder diagnosis per se, achieved significantly lower VO2 max when provided with heart-rate feedback. Moreover, diagnostic status interacted with levels of anxiety sensitivity to predict VO2 max. Patients with panic disorder display poorer cardiovascular fitness after controlling for anxiety and other factors that underestimate performance during fitness testing.     

Central AT(1) receptor blockade increases metabolic cost during exercise reducing mechanical efficiency and running performance in rats

The effect of central angiotensin AT(1) receptor blockade on metabolic rate and running performance in rats during exercise on a treadmill (18 m x min(-1), 5% inclination) was investigated. Oxygen consumption (VO(2)) was measured, using the indirect calorimetry system, while the animals were exercising until fatigue after injection of 2 microL of losartan (Los; 60 nmol, n=9), an angiotensin II AT(1) receptor antagonist, or 2 microL of 0.15 M NaCl (Sal, n=9) into the right lateral cerebral ventricle. Mechanical efficiency (ME) and workload (W) were calculated. The W performance by Los-treated animals was 29% lesser than in Sal-treated animals (p<0.02). During the first 10 min of exercise (dynamic state of exercise), there was a similar increase in VO(2), while ME remained the same in both groups. Thereafter (steady state of exercise), VO(2) remained stable in the Sal group but continued to increase and stabilized at a higher level in Los-treated animals until fatigue. During the steady state of exercise there was a sharper reduction in ME in Los-treated rats compared to Sal-treated animals (p<0.01) that was closely correlated to W (r=0.74; p<0.01). Our data showed that AT(1) receptor blockade increases metabolic cost during exercise, reducing mechanical efficiency. These results indicate that central angiotensinergic transmission modulates heat production, improving ME during the steady state of exercise.