Anaerobic threshold and maximal oxygen consumption during arm cranking exercise in paraplegia

Cardiac Autonomic Modulation of Heart Rate Recovery in Children with Spina Bifida

We aimed to analyse cardiac autonomic control by assessing the post-exercise heart rate recovery (HRR) and physical fitness in children and adolescents with spina bifida (SB), compared to participants with typical development. A total of 124 participants, 42 with spina bifida (SB group) and 82 typical developmental controls (CO group) performed the arm cranking exercise test with a gas analysis system. HRR was determined at the first (HRR_1) and second (HRR_2) minute at recovery phase. Data are shown as [mean difference (95% CI)]. The SB group showed reduced HR reserve [14.5 (7.1-22.0) bmp, P<0.01], slower HRR_1 [12.4 (7.4-17.5) bpm, P<0.01] and HRR_2 [16.3 (10.6-21.9) bpm; P<0.01], lower VO2peak [VO2peak relative: 7.3 (4.2-10.3) mL·min-1·kg-1, P<0.01; VO2peak absolute: 0.42 (0.30-0.54) L·min-1, P<0.01], and lower O2 pulse [2.5 (1.8-3.2) mL·bpm, P<0.01] and ventilatory responses [13.5 (8.8-18.1) L·min-1, P<0.01] than the CO group. VE/VO2 was not different between groups [-2.82 (-5.77- -0.12); P=0.06], but the VE/VCO2 [-2.59 (-4.40-0.78); P<0.01] and the values of the anaerobic threshold corrected by body mass [-3.2 (-5.8- -0.6) mL·min-1·kg-1, P=0.01] were higher in the SB group than in the CO group. We concluded that children and adolescents with SB have reduced physical fitness and a slower HRR response after maximal effort.

The Application of Creatine Supplementation in Medical Rehabilitation

Numerous health conditions affecting the musculoskeletal, cardiopulmonary, and nervous systems can result in physical dysfunction, impaired performance, muscle weakness, and disuse-induced atrophy. Due to its well-documented anabolic potential, creatine monohydrate has been investigated as a supplemental agent to mitigate the loss of muscle mass and function in a variety of acute and chronic conditions. A review of the literature was conducted to assess the current state of knowledge regarding the effects of creatine supplementation on rehabilitation from immobilization and injury, neurodegenerative diseases, cardiopulmonary disease, and other muscular disorders. Several of the findings are encouraging, showcasing creatine's potential efficacy as a supplemental agent via preservation of muscle mass, strength, and physical function; however, the results are not consistent. For multiple diseases, only a few creatine studies with small sample sizes have been published, making it difficult to draw definitive conclusions. Rationale for discordant findings is further complicated by differences in disease pathologies, intervention protocols, creatine dosing and duration, and patient population. While creatine supplementation demonstrates promise as a therapeutic aid, more research is needed to fill gaps in knowledge within medical rehabilitation.

Examination of gas exchange and blood lactate thresholds in Paralympic athletes during upper-body poling

Objectives

The primary aim was to compare physiological and perceptual outcome parameters identified at common gas exchange and blood lactate (BLa) thresholds in Paralympic athletes while upper-body poling. The secondary aim was to compare the fit of the breakpoint models used to identify thresholds in the gas exchange thresholds data versus continuous linear and curvilinear (no-breakpoint) models.

Methods

Fifteen elite Para ice hockey players performed seven to eight 5-min stages at increasing workload until exhaustion during upper-body poling. Two regression lines were fitted to the oxygen uptake (VO₂)-carbon dioxide (VCO₂) and minute ventilation (VE)/VO₂ data to determine the ventilatory threshold (VT), and to the VCO₂-VE and VE/VCO₂ data to determine the respiratory compensation threshold (RCT). The first lactate threshold (LT1) was determined by the first rise in BLa (+0.4mmol·L^-1 and +1.0mmol·L^-1) and a breakpoint in the log-log transformed VO₂-BLa data, and the second lactate threshold (LT2) by a fixed rise in BLa above 4mmol·L^-1 and by employing the modified D_max method. Paired-samples t-tests were used to compare the outcome parameters within and between the different threshold methods. The fit of the two regression lines (breakpoint model) used to identify thresholds in the gas exchange data was compared to that of a single regression line, an exponential and a 3^rd order polynomial curve (no-breakpoint models) by Akaike weights.

Results

All outcome parameters identified with the VT (i.e., breakpoints in the VO₂-VCO₂ or VE/VO₂ data) were significantly higher than the ones identified with a fixed rise in BLa (+0.4 or +1.0mmol·L^-1) at the LT1 (e.g. BLa: 5.1±2.2 or 4.9±1.8 vs 1.9±0.6 or 2.3±0.5mmol·L^-1,p<0.001), but were not significantly different from the log-log transformed VO₂-BLa data (4.3±1.6mmol·L^-1,p>0.06). The outcome parameters identified with breakpoints in the VCO₂-VE data to determine the RCT (e.g. BLa: 5.5±1.4mmol·L^-1) were not different from the ones identified with the modified D_max method at the LT2 (5.5±1.1mmol·L^-1) (all p>0.53), but were higher compared to parameters identified with VE/VCO₂ method (4.9±1.5mmol·L^-1) and a fixed BLa value of 4mmol·L^-1 (all p<0.03). Although we were able to determine the VT and RCT via different gas exchange threshold methods with good fit in all 15 participants (mean R²>0.931), the continuous no-breakpoint models had the highest probability (>68%) of being the best models for the VO₂-VCO₂ and the VCO₂-VE data.

Conclusions

In Paralympic athletes who exercise in the upper-body poling mode, the outcome parameters identified at the VT and the ones identified with fixed methods at the LT1 showed large differences, demonstrating that these cannot be used interchangeably to estimate the aerobic threshold. In addition, the close location of the VT, RCT and LT2 does not allow us to distinguish the aerobic and anaerobic threshold, indicating the presence of only one threshold in athletes with a disability exercising in an upper-body mode. Furthermore, the better fit of continuous no-breakpoint models indicates no presence of clear breakpoints in the gas exchange data for most participants. This makes us question if breakpoints in the gas exchange data really exist in an upper-body exercise mode in athletes with disabilities.

Health-related physical fitness of adolescents and young adults with myelomeningocele

To assess components of health-related physical fitness in adolescents and young adults with myelomeningocele (MMC), and to study relations between aerobic capacity and other health-related physical fitness components. This cross-sectional study included 50 adolescents and young adults with MMC, aged 16–30 years (25 males). Aerobic capacity was quantified by measuring peak oxygen uptake (peakVO₂) during a maximal exercise test on a cycle or arm ergometer depending on the main mode of ambulation. Muscle strength of upper and lower extremity muscles was assessed using a hand-held dynamometer. Regarding flexibility, we assessed mobility of hip, knee and ankle joints. Body composition was assessed by measuring thickness of four skin-folds. Relations were studied using linear regression analyses. Average peakVO₂ was 1.48 ± 0.52 l/min, 61% of the participants had subnormal muscle strength, 61% had mobility restrictions in at least one joint and average sum of four skin-folds was 74.8 ± 38.8 mm. PeakVO₂ was significantly related to gender, ambulatory status and muscle strength, explaining 55% of its variance. Adolescents and young adults with MMC have poor health-related physical fitness. Gender and ambulatory status are important determinants of peakVO₂. In addition, we found a small, but significant relationship between peakVO₂ and muscle strength.

The relationship between perceived exertion and physiologic indicators of stress during graded arm exercise in persons with spinal cord injuries

OBJECTIVE

To examine the relationship between psychologic cues of somatic stress and physiologic responses to exercise in persons with paraplegia and tetraplegia.

DESIGN

Repeated measures with 2 comparison groups.

SETTING

Academic medical center.

PARTICIPANTS

Forty-two subjects between 18 and 69 years of age with motor-complete spinal cord injury (SCI) resulting in paraplegia or tetraplegia (American Spinal Injury Association grades A and B).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Subjects underwent peak graded arm ergometry during which heart rate, oxygen consumption (VO2), minute ventilation (VE), and ratings of perceived exertion (RPE) (Borg Categorical 6-20 Scale) were measured at successive work rate increments from baseline to fatigue.

RESULTS

There were inconsistent associations among the outcomes. For subjects with tetraplegia, RPE related positively to heart rate at the initial work rate, but there were no other significant correlations. For subjects with paraplegia, RPE did not correlate significantly with heart rate, VO2, or VE. VO2 and Ve related positively at the first and last work rates. In general, heart rate, VO2, and Ve increased as the exercise intensity increased, and were more pronounced in subjects with paraplegia. While RPE values increased with increasing work rates for each group, we found no differences between groups.

CONCLUSIONS

Our findings contradict the well-accepted relationships between RPE and both heart rate and VO2 during exercise by people without disabilities, and challenge the use of RPE as a valid psychophysiologic index of perceived exertion in persons with SCI.

Postural responses during falling with rapid reach-and-grasp balance reaction in patients with motor complete paraplegia

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To investigate the kinematic, kinetic and electromyographic (EMG) aspects of postural control during falling with rapid reach-and-grasp balance reaction in thoracic cord-injured individuals wearing knee-ankle-foot orthoses (KAFOs).

SETTING

Institutional Motion Analysis Laboratory.

METHODS

Seven T7-T12 cord-injured subjects with complete motor loss (ASIA classes A and B) participated in this study. Subjects with KAFOs first stood steady with a modified walker and then released their hold on the walker to maintain self-supported standing until falling with grasping. The center of pressure (COP), center of mass (COM) and joint angles were measured together with EMG of the triceps (TRI), T4 paraspinal and abdominal muscles.

RESULTS

After release of the walker, there was a rapid increase of COM-COP distance (that is, from 13.32+/-11.79 to 54.29+/-24.56 mm), with COM in front of COP during a forward fall, which was associated with the increases of T4 muscle activities. After the reach-and-grasp reaction, COM moved behind COP, which was associated with the increase of ankle dorsiflexion and the TRI and abdominal muscle activities.

CONCLUSION

The increase of upper back extensor muscle activity might not be enough to correct postural instability during unsupported stance in thoracic spinal cord injury with complete motor loss. The rapid reach-and-grasp reaction is an alternative compensatory mechanism to prevent falling to the ground.

Development and qualitative assessment of the GAME(Cycle) exercise system

Increased physical activity is important for reducing the risk of cardiovascular disease. However, among people with disabilities, inactivity is prevalent. In order to encourage exercise among members of this group, an exercise system combining arm ergometry with video gaming, called the GAME(Cycle) was previously developed. User input was received through an arm crank ergometer on a swivel, with the angular velocity of the ergometer resistance wheel controlling one axis and rotation of ergometer about the swivel controlling the other. The purpose of this study was to detail the algorithms used in this device and present novel features included in a second generation of the GAME(Cycle). The features include a wheel on base, a steering return mechanism, and wireless fire buttons. A focus group of clinicians (n = 8), wheelchair users (n = 8), and clinician wheelchair users (n = 2) was conducted to evaluate the features of the GAME(Cycle). The focus group suggested improvements to the steering mechanism and to reduce vibration in the system. However, the focus group enjoyed the GAME(Cycle) and felt that it would encourage exercise among persons with disabilities.

Hypokinetic circulation in persons with paraplegia

INTRODUCTION

It is well established that hemodynamic dysfunction, resulting in diminished upper-extremity work capacity, occurs in persons with spinal cord injury (SCI) as compared with those who are nondisabled (ND). Although it has been shown that persons with paraplegia display higher values of heart rate (HR) with lower values of stroke volume (SV) during exercise, it is not resolved whether there is adequate compensation to produce similar values of cardiac output (.Q) as in ND.

PURPOSE

This study examined central cardiovascular responses (HR, SV, and .Q) of 20 subjects with complete thoracic level SCI (T(4)-T(11)) and 20 sedentary ND subjects during matched levels of arm-crank (AC) exercise.

METHODS

All subjects performed an incremental peak AC test to volitional exhaustion with continuous metabolic analysis and HR measurement via open circuit spirometry and 12-lead electrocardiography, respectively. Stroke volume was assessed using transthoracic impedance.

RESULTS

Heart rate was higher for SCI (P< 0.05) with significantly lower values for SV and .Q at rest (approximately 25%). Peak responses were significantly higher for ND in all factors except HR. Although subpeak HRs at matched absolute workloads were significantly higher for SCI (12-20 beats.min (-1) ), SV and .Q were significantly lower (P< 0.05).

CONCLUSIONS

The results of this study indicate that .Q is significantly lower in SCI than in ND during AC, despite significantly greater values of HR. These findings also suggest that the disparity in exercise values of .Q is related to differences exhibited at rest.

Physical fitness of lower limb amputees

OBJECTIVE

To investigate the cardiorespiratory endurance of the physical fitness of amputees and able-bodied subjects of the same ages and to demonstrate deterioration of the physical fitness of the amputees.

DESIGN

The test subjects were 31 amputees. Eighteen able-bodied persons served as controls. The incremental exercise test was performed to evaluate physical fitness. Sixteen of 31 amputees underwent endurance training by using a cycle ergometer driven by the intact leg, and their physical fitness was evaluated after completion of the endurance training program.

RESULTS

The Vo2max, anaerobic threshold, and maximum workload for the amputees were significantly lower than those of the able-bodied group. The equivalent values for the endurance training group before exercise treatment were 18.0, 12.1, and 63.9, respectively. After exercise treatment, these values significantly increased, and there was no significant difference from the able-bodied subjects.

CONCLUSIONS

This study showed that the physical fitness of amputees was clearly lower than that of the able-bodied subjects and that the amputees were able to recover from a poorly conditioned status after endurance training.

Physiology of wheelchair racing in athletes with spinal cord injury

Wheelchair racing is one of the most popular sporting activities of individuals with spinal cord injury. Athletes with this impairment have unique changes in metabolic, cardiorespiratory, neuromuscular and thermoregulatory systems, which reduce their overall physiological capacity compared with able-bodied individuals or individuals with other types of impairments. This review on spinal cord injury: presents the International Stoke Mandeville Games Federation classification of wheelchair athletes; describes methods commonly used to characterise anaerobic and aerobic fitness; presents the findings of physiological studies that have evaluated wheelchair racing performance; identifies the risks associated with temperature regulation when competing in wheelchair races; and discusses special conditions that can influence wheelchair racing performance. Currently there is limited research that has examined the relationship between sprint or distance wheelchair racing performance and the anaerobic and aerobic components of physical fitness. Although the descriptive evidence indicates that the profiles of these athletes reflect their training and participation in these specific events, the association between their physiological profiles and real or simulated racing performance is unclear. The generally accepted concept that high values of aerobic and anaerobic power are strongly correlated with endurance and sprint racing performance, respectively, are not necessarily true in this population. Athletes with spinal cord injury have an impaired thermoregulatory capacity, because the compromised autonomic and somatic nervous system functions disrupt control of skin blood flow and sweating below the level of the lesion. As a result, they may be more susceptible to hyperthermia during distance wheelchair racing performance. Wheelchair athletes should follow recommendations advocated for able-bodied individuals to minimise their risks of heat stress during competition. Many athletes with quadriplegia voluntarily induce autonomic dysreflexia (commonly known as boosting) during distance racing events to improve performance. Experimental evidence indicates that boosting can improve performance time by 10% in elite wheelchair marathon racers during simulated racing, as a result of increased oxygen utilisation in the boosted state. However, since boosting can be dangerous to health, the International Paralympic Committee has banned athletes from voluntarily inducing it during competition. The use of anti-gravity suits to increase lower-body positive pressure can increase the peak oxygen uptake, cardiac output and stroke volume. However, the use of abdominal binders does not influence these physiological responses. An effect of either of these techniques on wheelchair racing performance has not been demonstrated.

Oral creatine supplementation enhances upper extremity work capacity in persons with cervical-level spinal cord injury

OBJECTIVE

To examine the effects of short-term creatine monohydrate supplementation on the upper extremity work capacity of persons with cervical-level spinal cord injury (SCI).

DESIGN

Randomized, double-blind, placebo-controlled, crossover design study. Consists of 2 treatment phases lasting for 7 days, separated by a 21-day washout period.

SETTING

University research laboratory trial.

PARTICIPANTS

Sixteen men with complete cervical-level SCI (C5-7).

INTERVENTION

Subjects were randomly assigned to 1 of 2 groups and received either 20g/d of creatine monohydrate supplement powder or placebo maltodextrin powder for the first treatment phase; the treatment was reversed in the second phase. Incremental peak arm ergometry tests, using 2-minute work stages and 1-minute recovery periods, were performed immediately before and after each treatment phase (total of 4 assessments). The initial stage was performed unloaded, with power output progressively increased 10 watts/stage until subjects had achieved volitional exhaustion.

MAIN OUTCOME MEASURES

Peak power output, time to fatigue, heart rate, and metabolic measurements, including oxygen uptake (VO2), minute ventilation, tidal volume (VT), and respiration frequency.

RESULTS

Significantly greater values of VO2, VCO2, and VT at peak effort after creatine supplementation (P <.001).

CONCLUSIONS

Creatine supplementation enhances the exercise capacity in persons with complete cervical-level SCI and may promote greater exercise training benefits.

Does computer game play aid in motivation of exercise and increase metabolic activity during wheelchair ergometry?

GAME(Wheels) is an interface between a portable roller system and a computer that enables a wheelchair user to play commercially available computer video games. The subject controls the game play with the propulsion of their wheelchair's wheels on the rollers. The purpose of this study was to investigate whether using the GAME(Wheels) System during wheelchair propulsion exercise can help increase the individual's physiological response and aid in the motivation to exercise. Fifteen subjects participated in this study. The subjects propelled their wheelchairs on a portable roller that was equipped with the GAME(Wheels) System. There were two exercise trials consisting of 2 min of warm-up, 16 min of exercise and 2 min of cool-down. Physiological data (ventilation rate, oxygen consumption, heart rate) were collected. A significant difference (P<0.05) was found between exercise with GAME(Wheels) versus without GAME(Wheels) for average ventilation rate and average oxygen consumption. The differences were found during time periods of transition from warm-up to exercise, and before and after the midpoint of exercise. Written questionnaires showed that 87% of the individuals tested reported the system would help them work out on a regular basis. Playing the video game helped these individuals to reach their exercise training zone faster and maintain it for the entire exercise trial.

Evaluation of a manual wheelchair interface to computer games

The sedentary lifestyle of many people with spinal cord injury (SCI) has lead to cardiovascular diseases being a major health concern. A suitable exercise program may help improve the SCI individual's cardiovascular fitness level. GAMEWheels is an interface between a custom wheelchair roller system and a computer that enables an individual to control computer video games by driving his or her wheelchair. The purpose of Phase 1 was to evaluate the design of the GAMEWheels system and to determine the type of computer video game that is likely to motivate wheelchair users to exercise. Phase 2 included physiologic testing of wheelchair users and the GAMEWheels system to investigate whether the system elicits an exercise training response. Thirty-five subjects were recruited to evaluate the GAMEWheels by playing three commercial computer games (Phase 1) and to identify the computer game that they would prefer to use when exercising. The feedback from Phase 1 was used with test subjects to verify that the GAMEWheels system elicits an exercise training effect (Phase 2). Phase 2 included 10 subjects using the GAMEWheels system to play Need for Speed II. During game play, physiologic data were collected and the subjects' oxygen consumption and heart rate were analyzed. Analysis showed that the GAMEWheels system induced nine subjects to reach their training zone, defined as 50% and 60% of their maximum oxygen consumption and heart rate, respectively. This study demonstrates that the GAMEWheels system elicits an exercise training response.

Varying physiological response to arm-crank exercise in specific spinal injuries

The purpose of this arm-crank ergometry (ACE) study was to provide a greater understanding of the influence to which specific cervical and thoracic spinal cord injuries contribute to reduction in optimal cardio-respiratory and metabolic function. Twenty five male volunteers aged 20 to 47 years participated. Twenty disabled wheelchair-confined spinal cord injured (SCI) subjects were equally divided into four 'site-specific' groups based on the lesion being within either high- or low- cervical or thoracic anatomical regions. Five physically non-disabled controls (As) were included. Measured variables tended to decrease progressively from As to high-level quadriplegics. Analysis revealed a high variance in maximum cardio-respiratory performance levels between groups (P < 0.001). These findings confirm that limitation to upper body physical capabilities in the SCI during high-intensity ACE is dependent on specific lesion site. Considerable variability in performance levels were measured in those suffering lesions within closely approximating anatomical regions. Results also suggest a greater importance in the location of cervical rather than thoracic injuries in contributing towards higher relative losses in maximal cardio-respiratory and metabolic potential. Alterations in body composition and varying severity of muscle paralysis likely also play a contributing role in reducing optimal metabolic function in SCI individuals. The importance for stringent classification techniques of spinal cord lesion site in predicting upper body physical exercise potential in the SCI has therefore been highlighted in this study.

Oxygen uptake during peak graded exercise and single-stage fatigue tests of wheelchair propulsion in manual wheelchair users and the able-bodied

OBJECTIVE

To determine if a single-stage, submaximal fatigue test on a wheelchair ergometer would result in higher than expected energy expenditure.

DESIGN

An experimental survey design contrasting physiologic responses during peak graded exercise tests and fatigue tests.

SETTING

A rehabilitation science laboratory that included a prototypical wheelchair ergometer, open-circuit spirometry system, and heart rate monitor.

PARTICIPANTS

Nine able-bodied non-wheelchair users (the NWC group: 6 men and 3 women, mean +/- SD age 30 +/- 7yrs) and 15 manual wheelchair users (the WC group: 12 men and 3 women, age 40 +/- 9yrs, time in wheelchair 16 +/- 9yrs). No subject had any disease, medication regimen, or upper body neurologic, orthopedic, or other condition that would limit wheelchair exercise.

MAIN OUTCOME MEASURES

Peak oxygen uptake (VO2) for graded exercise testing and during fatigue testing, using a power output corresponding to 75% peak aerobic capacity on graded exercise test.

RESULTS

In the WC group, VO2 at 6 minutes of fatigue testing was not significantly different from peak VO2. In the NWC group, VO2 was similar to the expected level throughout fatigue testing.

CONCLUSION

Energy expenditure was higher than expected in the WC group but not in the NWC group. Fatigue testing may provide a useful evaluation of cardiorespiratory status in manual wheelchair users.

Physical performance and cardiovascular and metabolic adaptation of elite female wheelchair basketball players in wheelchair ergometry and in competition

Spinal cord injury leads to a pronounced reduction of cardiovascular, pulmonary, and metabolic ability. Physical activity, up to and including high-performance sports, has obtained importance in the course of rehabilitation and the postclinical phase. Thirteen elite female wheelchair basketball players from the German National Basketball Team and 10 female sedentary spinal cord-injured persons were examined in the study. Heart volume was measured by an echocardiography. All subjects underwent a graded exercise test on a wheelchair ergometer. Additionally, heart rate, lactate, and player points were measured during a competitive basketball game in wheelchair basketball players. Cardiac dimensions were larger for spinal cord-injured wheelchair basketball players (620.3 ml; 9.6 ml x kg(-1)) in comparison with spinal cord-injured persons (477.4 ml; 8.2 ml x kg(-1)) but did not exceed the heart volume of untrained nonhandicapped persons. In contrast, athletes with amputations or those having had poliomyelitis reached training-induced cardiac hypertrophy in relation to body mass (713.7 ml; 13.2 ml x kg(-1)), as observed in nonhandicapped athletes. During graded wheelchair ergometry, wheelchair basketball players showed a higher maximal work rate (59.9 v 45.5 W), maximal oxygen consumption (33.7 v 18.3 ml x min(-1) x kg(-1)), and maximal lactate (9.1 v 5.47 mmol x l(-1)) without a difference in maximal heart rate and workload at AT4 than did spinal cord-injured persons. The average heart rate during the wheelchair basketball game was 151 x min(-1), and the lactate concentration was 1.92 mmol x l(-1). Female athletes with a less severe handicap and higher maximal oxygen consumption during the graded exercise test reached a higher game level in the evaluation. During the competitive basketball game, high cardiovascular stress was observed, indicating a fast aerobic metabolism; the anaerobic lactic acid capacity played a subordinate role. Wheelchair basketball is an effective and suitable sport to enhance physical performance and to induce positive physiological adaptations.

Anaerobic work capacity in elite wheelchair athletes

To study the anaerobic work capacity in wheelchair athletes, 67 elite wheelchair athletes (50 male) were studied in a 30-second sprint test on a computer-controlled wheelchair ergometer during the World Championships and Games for the Disabled in Assen (1990). The experimental set-up (ergometer, protocol) proved to be adequate in terms of power output (P30, P5) velocity and heart rate. Male and female athletes were comparable with respect to personal characteristics (age, body weight, training hours). Track athletes (classified in 4 different functional classes) showed a class-related mean power output (P30: mean power produced during the 30-second sprint period) of 23, 68, 100, and 138 W for the male athletes (n = 38) and 38, 77, and 76 W for females in the upper three classes (n = 10). Sprint power was low for the group of subjects with cerebral palsy (35 W; mixed, n = 6) and relatively high for the amputee group (121 W; mixed, n = 6), female basketball players (81 W; n = 5), and two male field athletes (110 W). Significant differences between male and female athletes were found for P30 and P5 (highest mean power output over any of the six 5-second periods). As was to be expected, mean maximum heart rate in the sprint test varied significantly between the track groups from 112 (high lesion group) to 171 beats/minute(-1) (low lesion group) but not for both genders. The lower P30 in the T1 and T2 groups must be explained not only by the reduced functional muscle mass and impaired coordination but also by phenomena of cardiovascular dysfunction. Based on the performance parameters, the functional classification of the track athletes into four groups seems adequate. P30 was significantly associated with the personal characteristics of gender and hours of training. A significant correlation was found between P30 and sprint performance times for 200 meters (r = -0.79). No correlation was found between either of the forms of power output and the marathon times. Anaerobic wheelchair work capacity can be adequately studied with the 30-second sprint test that was used in this study. Anaerobic work capacity is highly variable among elite wheelchair athletes with different disabilities and from different sports disciplines and appeared quite strongly influenced by functionality, hours of training, and gender.

Tolerable exercise intensity in the early rehabilitation of paraplegic patients. A preliminary study

Accessible indicators for setting exertion levels in newly injured paraplegias could be useful to improve their daily and occupational performances in less time than is presently required. Eight male newly injured paraplegic subjects performed progressive resisted and endurance exercise tests on an arm cranking ergometer. Cardiorespiratory parameters during exercise were monitored with an oxygen uptake analyzer and perceived exertion was rated on Borg's 10-point scale. Four subjects (Group A) underwent an 'enhanced' rehabilitation protocol which included aerobic arm training sessions. The prescription of exercise intensity was tailored to each subject's tolerable power output for prolonged exertion. The remaining four (Group B) followed a 'conventional' rehabilitation program. Tests were repeated in both groups after 6 weeks. We observed a greater improvement in endurance capacity in Group A than in Group B after completion of the rehabilitation program. A 6-week 'enhanced' rehabilitation program based on a 'moderate' intensity of exercise was well tolerated and effective in improving the fitness levels of newly injured paraplegic subjects. Subjective perception has been shown to be a simple and accessible indicator for setting exertion levels.

Peak oxygen uptake and respiratory function in persons with spinal cord injury

This study investigated the association between peak oxygen uptake (peak VO2) during arm cranking exercise and respiratory function in paraplegics. Fourteen male paraplegics were recruited for the present study. The subjects were grouped according to the level of injury into the HL (Th3-Th8) and LL (Th11-L3) group. Prior to the maximal test, pulmonary function, including vital capacity (VC) and residual volume (RV), was measured in the sitting position. Mean peak VO2 in the LL group (1662 ml.min-1) was significantly greater than that in the HL group (1357 ml.min-1), corresponding to 82% of that in the LL group (P < or = 0.05). In respiratory function, the HL group showed marked restrictive impairment of ventilatory function. That is, VC and RV were significantly lower in the HL group than in the LL group (P < or = 0.05). The reduction in VC and RV is related to the degree of loss of control in respiratory functioning muscle mass. However, there was no clear-cut correlation between respiratory function and peak VO2 expressed as a function of body mass (ml.kg-1.min-1). In addition, a multiple linear regression analysis revealed that RV and VC were not associated with peak VO2 (ml.min-1) in contrast to the importance of body mass. It seems reasonable to conclude from these results that respiratory function is not an important factor in determining peak VO2 in the paraplegic.