Wheelchair propulsion: effects of experience and push strategy on efficiency and perceived exertion

Contribution of Physical Characteristics to Game Performance in Male Wheelchair Basketball Athletes at the Tokyo Paralympic Games

ABSTRACT

Snyder, L, Goods, PSR, Peeling, P, Balloch, A, Peiffer, JJ, Binnie, MJ, and Scott, BR. Contribution of physical characteristics to game performance in male wheelchair basketball athletes at the Tokyo Paralympic Games. J Strength Cond Res XX(X): 000-000, 2024-This investigation explored the physical characteristics of elite male wheelchair basketball (WCB) athletes and their association with game performance during the Tokyo 2020 Paralympic Games. Sixteen male athletes from the Australian national WCB squad were assessed for anthropometrics, speed, change of direction, aerobic power, and upper-body power during a training camp before the 2020 Paralympic Games. Athletes were grouped according to the International Wheelchair Basketball Federation disability classification system (1.0-4.5) as low- (≤2.5, more severe impairments) or high-point (≥3.0, less severe impairments) athletes. Physical and performance characteristics between groups were compared using independent-samples t-tests, and their relationship to game statistics (points, rebounds, assists, and steals) per minute played was explored through stepwise regression. High-point athletes were 13% taller (p = 0.001), 4-9% faster (p < 0.001-0.017), and demonstrated superior change of direction ability (15%, p < 0.001) compared with low-point athletes. Approximately 74% of the variance in points scored per minute was accounted for by athlete classification, whereas the most important modifiable physical characteristic was speed, which contributed significantly to steals (54% of variance) and assists (96% of variance when arm span and sitting reach height were also considered). Low-point athletes with spinal cord injuries generally have impaired trunk control, which is a likely explanation for performance differences between groups. A range of nonmodifiable (classification, sitting reach height, and arm span) and modifiable (speed) physical characteristics contribute to game performance outcomes and should therefore be considered when identifying, developing, and selecting WCB athletes for elite competition.

Evaluation of two power assist systems for manual wheelchairs for usability, performance and mobility: a pilot study

BACKGROUND

Power-assist devices for manual wheelchairs offer benefits, including increased community participation. Several power-assist devices are commercially available, but research on benefits and limitations of devices is limited.

OBJECTIVE

To compare the usability, performance, and mobility of two power-assist device systems for manual wheelchairs in indoor and outdoor environments.

METHODS

This mixed methods pilot study included 11 volunteers with limited wheelchair experience. Participants tested two different power-assist device configurations: (1) the Batec® and (2) the SmartDrive® + Freewheel®. Indoor & outdoor obstacle courses contained relevant skills from the Wheelchair Skills Test, Power Mobility Community Driving Assessment, and Power Mobility Indoor Driving Assessment. The NASA Task Load Index and System Usability Scale assessed participants' perceptions of cognitive demand and usability. A semi-structured interview was conducted to explore participants' experiences.

RESULTS

Substantial differences were found in the NASA Task Load Index, and System Usability Scale scores. Participant interviews and researcher observations revealed each device performed better on some obstacle course elements. Qualitative findings showed a general preference for using the Batec® for long trips outside and off-road terrains, primarily due to the Batec's® perceived better speed control, maximum speed, and simpler braking system. Conversely, the SmartDrive® + Freewheel® was deemed most useful indoors and in tight spaces; due to a smaller wheelchair footprint, better turning radius, and increased device portability.

CONCLUSION

Further studies are required to understand the usability, performance, and mobility of power-assist devices. Moving forward, these findings will inform end users and occupational therapists when procuring manual wheelchair power-assist devices.Implications for rehabilitationPower-assist devices (PADs) for manual wheelchairs increase the potential for community participation.Qualitative findings showed a general preference for using the Batec® for long trips outside and for off-road terrains, primarily due to the Batec's® perceived better speed control, maximum speed, and simpler braking system.The SmartDrive® + Freewheel® was deemed most useful indoors and in tight spaces; due to a smaller wheelchair footprint, better turning radius, and increased device portability.Increasing knowledge and research about PADs will support development of alternative options for manual or power wheelchairs users. PADs may allow manual wheelchair users (MWC) to delay moving to a power wheelchair (PWC), potentially reducing the perceived stigma associated with transitioning to a power wheelchair and impacting health outcomes.

Evaluation of a standardized test protocol to measure wheelchair-specific anaerobic and aerobic exercise capacity in healthy novices on an instrumented roller ergometer

This study aims to evaluate whether a test protocol with standardized and individualized resistance settings leads to valid wheelchair Wingate tests (WAnT) and graded exercise tests (GXT) in healthy novices. Twenty able-bodied individuals (10M/10F, age 23 ± 2 years, body mass 72 ± 11 kg) performed an isometric strength test, sprint test, WAnT and GXT on a wheelchair ergometer. Using a previously developed set of regression equations, individuals’ isometric strength outcome was used to estimate the WAnT result (P30_est), from which an effective individual WAnT resistance was derived. The subsequently measured WAnT outcome (P30_meas) was used to estimate the GXT outcome (POpeak_est) and to scale the individual GXT resistance steps. Estimated and measured outcomes were compared. The WAnT protocol was considered valid when maximal velocity did not exceed 3 m·s^-1; the GXT protocol was considered valid when test duration was 8–12 min. P30_est did not significantly differ from P30_meas, while one participant did not have a valid WanT, as maximal velocity exceeded 3 m·s^-1. POpeak_est was 10% higher than POpeak_meas, and six participants did not reach a valid GXT: five participants had a test duration under 8 min and one participant over 12 min. The isometric strength test can be used to individually scale the WAnT protocol. The WAnT outcome scaled the protocol for the GXT less accurately, resulting in mostly shorter-than-desired test durations. In conclusion, the evaluated standardized and individualized test protocol was valid for the WAnT but less valid for the GXT among a group of novices. Before implementing the standardized individual test protocol on a broader scale, e.g. among paralympic athletes, it should be evaluated among different athletic wheelchair-dependent populations.

Criterion Validity of a Field-Based Assessment of Aerobic Capacity in Wheelchair Rugby Athletes

PURPOSE

To confirm whether peak aerobic capacity determined during laboratory testing could be replicated during an on-court field-based test in wheelchair rugby players.

METHODS

Sixteen wheelchair rugby players performed an incremental speed-based peak oxygen uptake (V˙O2peak) test on a motorized treadmill (TM) and completed a multistage fitness test (MFT) on a basketball court in a counterbalanced order, while spirometric data were recorded. A paired t test was performed to check for systematic error between tests. A Bland-Altman plot for V˙O2peak illustrated the agreement between the TM and MFT results and how this related to the boundaries of practical equivalence.

RESULTS

No significant differences between mean V˙O2peak were reported (TM: 1.85 [0.63] vs MFT: 1.81 [0.63] L·min-1; P = .33). Bland-Altman plot for V˙O2peak suggests that the mean values are in good agreement at the group level; that is, the exact 95% confidence limits for the ratio systematic error (0.95-1.02) are within the boundaries of practical equivalence (0.88-1.13) showing that the group average TM and MFT values are interchangeable. However, consideration of the data at the level of the individual athlete suggests that the TM and MFT results were not interchangeable because the 95% ratio limits of agreement either coincide with the boundaries of practical equivalence (upper limit) or fall outside (lower limit).

CONCLUSIONS

Results suggest that the MFT provides a suitable test at a group level with this cohort of wheelchair rugby players for the assessment of V˙O2peak (range 0.97-3.64 L·min-1), yet caution is noted for interchangeable use of values between tests for individual players.

Investigating the test-retest reliability of Illinois Agility Test for wheelchair users

The Illinois Agility Test (IAT) is a standard agility course used to assess and train able-bodied athletes as well as wheelchair-sport athletes and rehabilitation of wheelchair users. It has been shown to be a reliable and valid tool to assess the able-bodied population, but the reliability of this test for assessing wheelchair propulsion has never been shown. The purpose of this study is to investigate the test-retest reliability of IAT to assess wheelchair propulsion. In this paper, the test-retest reliability of using IAT for wheelchair users is found for peak and average velocity, acceleration, tangential and total force of the push, each for the left and the right wheel. Each of these variables was found for thirty-two decisive points throughout the IAT path. The Intra-class Correlation Coefficient (ICC) was found to be very strong for 15 out of 16 variables. The average ICC was 89% and the average 95% confidence interval was [44% 96%]. In addition, thirty-seven other significant propulsion parameters were found that are clinically important, such as the number of pushes participants take to go around cones on the right, relative to turning around the cones on the left. Also, all thirty-seven variables were compared between the two sessions using four separate MANOVAs; the results showed no significant difference between IAT performed in the two sessions which were at least one week apart. This, in turn, backs the reliability of IAT for wheelchair users. These results are sufficient evidence to show that IAT is a reliable tool to test wheelchair agility for fifteen variables tested for non-wheelchair users. Since experienced wheelchair users are much more consistent in wheelchair propulsion compared to non-wheelchair-users, the results of this study show that IAT can be used as a reliable tool to assess and train wheelchair users, both for clinical and athletic applications.

Relationship Between Power Output and Speed-Related Performance in Brazilian Wheelchair Basketball Players

This study aimed to investigate the association between the optimum power load in the bench press (BP), shoulder press (SP), and prone bench pull (PBP) exercises and acceleration (ACC) and speed performances in 11 National Team wheelchair basketball (WB) players with similar levels of disability. All athletes were previously familiarized with the testing procedures that were performed on the same day during the competitive period of the season. First, athletes performed a wheelchair 20-m sprint assessment and, subsequently, a maximum power load test to determine the mean propulsive power (MPP) in the BP, SP, and PBP. A Pearson product-moment correlation was used to examine the relationships between sprint velocity (VEL), ACC, and the MPP in the three exercises. The significance level was set as p < .05. Large to very large significant associations were observed between VEL and ACC and the MPP in the BP, SP, and PBP exercises (r varying from .60 to .77; p < .05). The results reveal that WB players who produce more power in these three exercises are also able to accelerate faster and achieve higher speeds over short distances. Given the key importance of high and successive ACCs during wheelchair game-related maneuvers, it is recommended that coaches frequently assess the optimum power load in BP, SP, and PBP in WB players, even during their regular training sessions.

Evaluation of two wheelchair hand rim models: contact pressure distribution in straight line and curve trajectories

Manual wheelchairs are essential for people with disabilities or limited mobility. However, manual propulsion causes biomechanical loads, including contact pressures on the palms of the hands. The hand rim design has received little attention over time, remaining almost unchanged since its creation. This study investigated how two different designs of such devices - one standard and another with a contoured design - influence the contact pressure on the surface of the hands. The procedures included a figure-of-eight shape propulsion task on a regular floor, using both models on a wheelchair. A pressure-mapping system coupled with a pair of fabric gloves recorded the data. The results show that the contoured hand rim provides lower pressure in most of the analysed regions. Considering that manual propulsion is performed during a considerable part of the day as a routine activity, improving the hand rim interface may benefit the user's comfort and safety during wheelchair use. Practitioner summary: The design of the hand rim used in wheelchair propulsion influences the contact pressure on the hands. Conventional round tube rims tend to concentrate high levels of pressure on the distal phalanges and metacarpal regions. A contoured design generally provides better stability and promotes the distribution of pressure. Abbreviations: AT: assistive technology; kPa: kilopascal.

Perceived exertion responses to wheelchair propulsion differ between novice able-bodied and trained wheelchair sportspeople

OBJECTIVES

To investigate peripheral (RPE_P) and central (RPE_C) Ratings of Perceived Exertion during wheelchair propulsion in untrained able-bodied (AB) participants, and trained wheelchair rugby athletes with and without cervical spinal cord injury (CSCI).

DESIGN

Cross-sectional study.

METHODS

38 participants (AB: n=20; wheelchair rugby athletes with CSCI: n=9; without CSCI: n=9) completed an incremental wheelchair propulsion test to exhaustion on a motorised treadmill. Gas exchange measures and heart rate (HR) were collected throughout. RPE_P and RPE_C on the Category Ratio-10 were verbally recorded each minute. Blood lactate concentration ([BLa]) was determined post-test.

RESULTS

Between 50-100% peak oxygen uptake (V̇O_2peak), RPE_P was greater than RPE_C in AB (p<0.05), but not in athletes with (p=0.07) or without (p=0.16) CSCI. RPE_P was greater in AB compared to players with CSCI (Effect sizes: 1.24-1.62), as were respiratory exchange ratio (1.02±0.10 vs 0.82±0.11, p<0.05) and [BLa]_peak (7.98±2.53 vs 4.66±1.57mmol·L^-1). RPE_C was greater in athletes without CSCI compared to those with CSCI (Effect sizes: 0.70-1.38), as were HR (166±20 vs 104±15 beats·min^-1, p<0.05) and ventilation (59.2±28.8 vs 35.1±16.6L·min^-1, p=0.01).

CONCLUSIONS

RPE_P was dominant over RPE_C during wheelchair propulsion for untrained AB participants. For athletes with CSCI, lower RPE_P and RPE_C were reported at the same %V̇O_2peak compared to those without CSCI. The mechanism for this remains to be fully elucidated.

Motor learning outcomes of handrim wheelchair propulsion during active spinal cord injury rehabilitation in comparison with experienced wheelchair users

PURPOSE

To investigate changes in wheelchair propulsion technique and mechanical efficiency across first five weeks of active inpatient spinal cord injury rehabilitation and to compare the outcomes at discharge with experienced wheelchair users with spinal cord injury.

METHODS

Eight individuals with recent spinal cord injury performed six weekly submaximal exercise tests. The first and last measurement additionally contained a wheelchair circuit and peak graded exercise test. Fifteen experienced individuals performed all above-mentioned tests on one occasion.

RESULTS

Mechanical efficiency and propulsion technique did not change during the five weeks of inpatient rehabilitation. Peak power output during peak graded test and performance time on the wheelchair circuit improved between the first and the last week. No difference in propulsion technique, peak power output, and performance time was found between the persons with a recent injury and the experienced group. Mechanical efficiency was higher after the correction for the difference in relative power output in the experienced group.

CONCLUSION

The group with a recent injury did not improve mechanical efficiency and propulsion technique over the period of active rehabilitation, despite significant improvements on the wheelchair circuit and in work capacity. The only significant difference between the groups was found in mechanical efficiency.Implications for rehabilitationThe lack of time-dependent changes in mechanical efficiency and propulsion technique in the group with a recent spinal cord injury, combined with the lack of differences in technique, work capacity and on the wheelchair circuit between the groups, suggest that important adaptations of motor learning may happen even earlier in rehabilitation and emphasize that the group in active rehabilitation was relatively skilled.Standardized observational analyses of handrim wheelchair propulsion abilities during early spinal cord injury rehabilitation provide detailed understanding of wheelchair technique, skill as well as wheelchair propulsion capacity.Measurement of external power output is critical to interpretation of gross efficiency, propulsion technique, and capacity.Wheelchair quality and body weight - next to wheelchair fitness and skill - require careful consideration both in early rehabilitation as well as in the chronic phase of spinal cord injury.

Shoulder and thorax kinematics contribute to increased power output of competitive handcyclists

Current knowledge of recumbent handbike configuration and handcycling technique is limited. The purpose of this study was to evaluate and compare the upper limb kinematics and handbike configurations of recreational and competitive recumbent handcyclists, during sport‐specific intensities. Thirteen handcyclists were divided into two significantly different groups based on peak aerobic power output (PO_peak) and race experience; competitive (n = 7; 5 H3 and 2 H4 classes; PO_peak: 247 ± 20 W) and recreational (n = 6; 4 H3 and 2 H4 classes; PO_peak: 198 ± 21 W). Participants performed bouts of exercise at training (50% PO_peak), competition (70% PO_peak), and sprint intensity while three‐dimensional kinematic data (thorax, scapula, shoulder, elbow, and wrist) were collected. Statistical parametric mapping was used to compare the kinematics of competitive and recreational handcyclists. Handbike configurations were determined from additional markers on the handbike. Competitive handcyclists flexed their thorax (~5°, P < 0.05), extended their shoulder (~10°, P < 0.01), and posteriorly tilted their scapular (~15°, P < 0.05) more than recreational handcyclists. Differences in scapular motion occurred only at training intensity while differences in shoulder extension and thorax flexion occurred both at training and competition intensities. No differences were observed during sprinting. No significant differences in handbike configuration were identified. This study is the first to compare the upper limb kinematics of competitive recreational handcyclists at sport‐specific intensities. Competitive handcyclists employed significantly different propulsion strategies at training and competition intensities. Since no differences in handbike configuration were identified, these kinematic differences could be due to technical training adaptations potentially optimizing muscle recruitment or force generation of the arm.

The influence of operator and wheelchair factors on wheelchair propulsion effort

Purpose: The goal of this study was to evaluate the relative influence of operator and wheelchair factors on propulsion effort during over-ground wheelchair manoeuvres.Method: This observational study included 23 full-time manual wheelchair users and 13 able-bodied subjects. The operator factors included shoulder position, aerobic capacity and propulsion strength. The wheelchair factors included system mass, weight distribution, and frictional loss in straight and turning trajectories. The performance of over-ground manoeuvres was defined as the propulsion effort measured by VO₂ as operators propelled along a modified figure-8 course on tile and carpet surfaces.Results: According to our regression model, shoulder position was the only significant contributor within operator factors, whereas weight distribution was the only significant contributor within wheelchair factors in influencing propulsion efforts. When combining operator and mechanical factors in the regression model, weight distribution became the only significant contributor to influence propulsion effort.Conclusion: Weight distribution and shoulder position had a significant influence on propulsion effort. These variables are related to the operator's relationship to the drive wheels. However, system mass and muscle strength had the least influence on wheelchair manoeuvres. Our finding can help clinicians to improve wheelchair configurations and manufacturers to improve wheelchair design by understanding the importance of shoulder position and weight distribution.Implication for rehabilitationStudying wheelchair manoeuvers by considering both wheelchair and operator factors might provide a unique insight to address the complex interactions among wheelchair designs and users.Propulsion effort decreases as percentage weight is increased on the drive wheels and the shoulder becomes more aligned with the axle position, which highlights the need to optimize wheelchair axle position.Wheelchair configuration, as represented by weight distribution, had a more significant influence on everyday manoeuvre than wheelchair mass does.It is essential for wheelchair users to choose a wheelchair that can match their daily needs and anthropometric measurements for saving propulsion efforts.

Differences in Physiological Responses During Wheelchair Basketball Matches According to Playing Time and Competition

PURPOSE

The main purpose of the present study was to determine physiological responses in wheelchair basketball (WB) matches in relation to heart rate (HR), match load (ML), differentiated perceived exertion (dRPE), lactate concentrations (LA), and tympanic temperature (TEMP), while specifying the individual player's playing time during different types of matches.

METHOD

Nine Spanish First Division WB players participated in the study. Three groups were determined for each observation (i.e., HR, ML, dRPE, LA, and TEMP) according to the minutes played by the WB players: players who had played 30 min to 40 min (WB_30-40), those who played 20 min to 30 min, and those who played 0 min to 20 min.

RESULTS

The WB_30-40 group attained statistically significantly higher results in mean HR than the other groups in league and playoff matches (p < .05; Δ% > -25.73%; ES > -1.31, large). With regard to the difference in each variable between league and playoff matches, the differences were highlighted in the WB_30-40 group according to ML (Edwards, p < .05, Δ% = -11.14%, ES = -0.87, large; Stagno's modified TRIMP, p < .05, Δ% = -16.95%, ES = -0.77, large). Tympanic temperature also reached higher values in playoff matches compared with league matches in WB_30-40 (p < .05; Δ% = 1.1%; ES = 0.67, moderate) but not in LA values.

CONCLUSIONS

Coaches should take into account that playoff matches were more demanding than league matches, thus forcing coaches to try to peak WB players' physical performance for the former.

The embodied nurse: Interdisciplinary knowledge exchange between compassionate nursing and recent developments in embodied leadership studies

AIMS

To report a potential knowledge exchange between nursing studies and the results obtained from a study conducted into the attributes of embodied leadership.

BACKGROUND

Leadership theories have been applied to evaluate, improve, and train nursing practitioners in several previous studies. However, leadership research has entered a new phase where the focus is to produce sustainable leaders through authenticity and compassion, the same two characteristics identified as being of most success in emergent nursing practice. There are few studies that have indicated a knowledge exchange between the latest developments in leadership studies and nursing.

DESIGN

An exploratory and qualitative study.

METHODS

Between February 2012 - July 2012, a focused sample of 14 medical care professionals was interviewed across a chain of hospitals. The aim was to evaluate embodied leadership characteristics and understand the factors that contribute to the manifestation of these characteristics. The transcribed interviews were analysed using thematic analysis.

FINDINGS

Several factors that contribute to the characteristics of embodied leadership have been identified in the interviews and in subsequent literature searches on the characteristics and contributing factors found to be associated with nursing research. These could prompt a knowledge exchange.

CONCLUSION

The results suggest common ground between nursing and contemporary leadership research in the exposition of behaviours; namely, being non-judgmental, listening actively, reflective practice and embracing uncertainty. Several implications can therefore be expected through the exchange of knowledge resulting from collaboration between researchers in the two disciplines.

The physiological and biomechanical effects of forwards and reverse sports wheelchair propulsion

OBJECTIVE

To explore the physiological and biomechanical differences between forwards (FOR) and reverse (REV) sports wheelchair propulsion.

DESIGN

Fourteen able-bodied males with previous wheelchair propulsion experience pushed a sports wheelchair on a single-roller ergometer in a FOR and REV direction at three sub-maximal speeds (4, 6, and 8 km/hour). Each trial lasted 3 minutes, and during the final minute physiological and biomechanical measures was collected.

RESULTS

The physiological results revealed that oxygen uptake (1.51 ± 0.29 vs. 1.38 ± 0.26 L/minute, P = 0.005) and heart rate (121 ± 19 vs. 109 ± 14 beats/minute, P < 0.0005) were significantly greater during REV than FOR only during the 8 km/hour trials. From a biomechanical perspective, push frequencies were similar between FOR and REV across all speeds (P > 0.05). However, greater mean resultant forces were applied during FOR (P < 0.0005) at 4 km/hour (66.7 ± 19.5 vs. 49.2 ± 10.3 N), 6 km/hour (90.7 ± 21.9 vs. 65.3 ± 18.6 N), and 8 km/hour (102.5 ± 17.6 vs. 68.7 ± 13.5 N) compared to REV. Alternatively, push times and push angles were significantly lower (P ≤ 0.001) during FOR at each speed.

CONCLUSIONS

The current study demonstrated that at higher speeds physiological demand becomes elevated during REV. This was likely to be associated with an inability to apply sufficient force to the wheels, thus requiring kinematic adaptations in order to maintain constant speeds in REV.

Wheelchair users' perceived exertion during typical mobility activities

STUDY DESIGN

Each participant performed a series of wheelchair exercises equivalent in intensity to minimal functional speed (1 m s(-1)), functional walking speed (1.3 m s(-1)), a relatively challenging speed (1.6 m s(-1)) and a self-selected speed. Each participant also completed a graded exercise test (GXT) to volitional exhaustion (VO2peak).

OBJECTIVES

The purpose of this study was (1) to assess the physical capacity of wheelchair users as they undertake typical mobility activities and (2) to investigate how closely the components of a differentiated model of perceived exertion mirror wheelchair users' own perception of exertion.

METHODS

Eleven (eight males and three females) spinal cord-injured or congenitally impaired wheelchair-dependent participants volunteered for the study. Differentiated ratings of perceived exertion (RPE_arm and RPE_respiration) and oxygen uptake (VO2) and heart rate were recorded during each exercise.

RESULTS

The mean comfortable speed at which the participants propelled their own wheelchairs on the wheelchair ergometer was 1.1±0.2 m s(-1). Speeds of 1 m s(-1) and 1.3 m s(-1) are typical of everyday functional propulsion. The corresponding RPE_respiration and RPE_arm ranged from 7 to 13 on the Borg scale; the %VO2peak measured in these trials ranged from 37 to 80% VO2peak. For propulsion intensities used in the present study-low, moderate, high and graded exercise intensity-no difference could be observed between RPE_respiration and RPE_arm. There were no significant differences between RPE_arm and RPE_respiration at the termination of the GXT.

CONCLUSION

The current study showed potential for the use of RPE to assess and monitor daily wheelchair propulsion intensity in individuals with paraplegia.

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

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.

Predicting energy expenditure through hand rim propulsion power output in individuals who use wheelchairs

AIM

To examine the relationship between hand rim propulsion power and energy expenditure (EE) during wheelchair wheeling and to investigate whether adding other variables to the model could improve on the prediction of EE.

METHODS

Individuals who use manual wheelchairs (n=14) performed five different wheeling activities in a wheelchair with a PowerTap power meter hub built into the right rear wheel. Activities included wheeling on a smooth, level surface at three different speeds (4.5, 5.5 and 6.5 km/h), wheeling on a rubberised track at one speed (5.5 km/h) and wheeling on a sidewalk course that included uphill and downhill segments at a self-selected speed. EE was measured using a portable indirect calorimetry system. Stepwise linear regression was performed to predict EE from power output variables. A repeated-measures analysis of variance was used to compare the measured EE to the estimates from the power models. Bland-Altman plots were used to assess the agreement between the criterion values and the predicted values.

RESULTS

EE and power were significantly correlated (r=0.694, p<0.001). Regression analysis yielded three significant prediction models utilising measured power; measured power and speed; and measured power, speed and heart rate. No significant differences were found between measured EE and any of the prediction models.

CONCLUSION

EE can be accurately and precisely estimated based on hand rim propulsion power. These results indicate that power could be used as a method to assess EE in individuals who use wheelchairs.

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion

The purpose of this study was to (1) evaluate the mechanical efficiency (ME) of two commercially available lever-propulsion mechanisms for wheelchairs and (2) compare the ME of lever propulsion with hand rim propulsion within the same wheelchair. Of the two mechanisms, one contained a torsion spring while the other used a roller clutch design. We hypothesized that the torsion spring mechanism would increase the ME of propulsion due to a passive recovery stroke enabled by the mechanism. Ten nondisabled male participants with no prior manual wheeling experience performed submaximal exercise tests using both lever-propulsion mechanisms and hand rim propulsion on two different wheelchairs. Cardiopulmonary parameters including oxygen uptake (VO2), heart rate (HR), and energy expenditure (En) were determined. Total external power (Pext) was measured using a drag test protocol. ME was determined by the ratio of Pext to En. Results indicated no significant effect of lever-propulsion mechanism for all physiological measures tested. This suggests that the torsion spring did not result in a physiological benefit compared with the roller clutch mechanism. However, both lever-propulsion mechanisms showed decreased VO2 and HR and increased ME (as a function of slope) compared with hand rim propulsion (p < 0.001). This indicates that both lever-propulsion mechanisms tested are more mechanically efficient than conventional hand rim propulsion, especially when slopes are encountered.

Partitioning kinetic energy during freewheeling wheelchair maneuvers

This paper describes a systematic method to partition the kinetic energy (KE) of a free-wheeling wheelchair. An ultralightweight rigid frame wheelchair was instrumented with two axle-mounted encoders and data acquisition equipment to accurately measure the velocity of the drive wheels. A mathematical model was created combining physical specifications and geometry of the wheelchair and its components. Two able-bodied subjects propelled the wheelchair over four courses that involved straight and turning maneuvers at differing speeds. The KE of the wheelchair was divided into three components: translational, rotational, and turning energy. This technique was sensitive to the changing contributions of the three energy components across maneuvers. Translational energy represented the major component of total KE in all maneuvers except a zero radius turn in which turning energy was dominant. Both translational and rotational energies are directly related to wheelchair speed. Partitioning KE offers a useful means of investigating the dynamics of a moving wheelchair. The described technique permits analysis of KE imparted to the wheelchair during maneuvers involving changes in speed and direction, which are most representative of mobility in everyday life. This technique can be used to study the effort required to maneuver different types and configurations of wheelchairs.

Field-based physiological testing of wheelchair athletes

The volume of literature on field-based physiological testing of wheelchair sports, such as basketball, rugby and tennis, is considerably smaller when compared with that available for individuals and team athletes in able-bodied (AB) sports. In analogy to the AB literature, it is recognized that performance in wheelchair sports not only relies on fitness, but also sport-specific skills, experience and technical proficiency. However, in contrast to AB sports, two major components contribute towards 'wheeled sports' performance, which are the athlete and the wheelchair. It is the interaction of these two that enable wheelchair propulsion and the sporting movements required within a given sport. Like any other athlete, participants of wheelchair sports are looking for efficient ways to train and/or analyse their technique and fitness to improve their performance. Consequently, laboratory and/or field-based physiological monitoring tools used at regular intervals at key time points throughout the year must be considered to help with training evaluation. The present review examines methods available in the literature to assess wheelchair sports fitness in a field-based environment, with special attention on outcome variables, validity and reliability issues, and non-physiological influences on performance. It also lays out the context of field-based testing by providing details about the Paralympic court sports and the impacts of a disability on sporting performance. Due to the limited availability of specialized equipment for testing wheelchair-dependent participants in the laboratory, the adoption of field-based testing has become the preferred option by team coaches of wheelchair athletes. An obvious advantage of field-based testing is that large groups of athletes can be tested in less time. Furthermore, athletes are tested in their natural environment (using their normal sports wheelchair set-up and floor surface), potentially making the results of such testing more relevant than laboratory testing. However, given that many tests, such as the multistage fitness test and the Yo-Yo intermittent test, have originally been developed for AB games players, the assumption that these can also be used for wheelchair athletes may be erroneous. With the array of AB aerobic and anaerobic field tests available, it is difficult to ascertain which ones may be best suited for wheelchair athletes. Therefore, new, wheelchair sport-specific tests have been proposed and validated. Careful selection of tests to enable coaches to distinguish between disability classifications, wheelchair proficiency and actual performance improvements is paramount as this will not only enhance the value of field-based testing, but also help with the development of meaningful normative data.

Subjective measures of exercise intensity to gauge substrate partitioning in persons with paraplegia

BACKGROUND

The Borg Rating of Perceived Exertion (RPE) Scale and talk test (TT) are commonly recommended for persons to gauge exercise intensity. It is not known whether they are suitable to estimate substrate partitioning between carbohydrate and fat in persons with SCI.

OBJECTIVE

Investigate substrate partitioning/utilization patterns associated with RPE and TT.

METHODS

Twelve participants with chronic paraplegia underwent 2 arm crank exercise tests on nonconsecutive days within 2 weeks. Test 1 was a graded exercise test (GXT) to volitional exhaustion. Test 2 was a 15-minute self-selected steady state (SS) voluntary arm exercise bout simulating a brief, yet typical exercise session.

RESULTS

For the GXT, very light intensity exercise (RPE < 9) and TT stage before last positive were associated with highest contribution of fat oxidation (~35%-50%) to total energy expenditure (TEE). Fat oxidation was low at all stages, with the highest rate (0.13 ± 0.07 g/min) occurring at stage 1 (10 W). Corresponding average RPE was 7 ± 2 and the TT was positive for all participants at this stage. For the SS, fuel partitioning throughout exercise was dominated by carbohydrate oxidation (1.47 ± 0.08 g/min), accounting for almost all (~94%) of TEE with only a minute contribution from fat oxidation (0.02 ± 0.004 g/min). A positive TT was associated with an average contribution of fat oxidation of ~10%.

CONCLUSIONS

RPE but not the TT appears suitable to predict exercise intensities associated with the highest levels of fat oxidation. However, such intensities are below authoritative intensity thresholds for cardiorespiratory fitness promotion, and therefore the applicability of such a prediction for exercise prescriptions is likely limited to individuals with low exercise tolerance.

Differentiated perceived exertion and self-regulated wheelchair exercise

OBJECTIVE

To investigate the utility of the differentiated rating of perceived exertion (RPE) for the self-regulation of submaximal wheelchair propulsion in novice users.

DESIGN

Each participant completed a submaximal incremental test and a graded test to exhaustion to determine peak oxygen consumption (Vo(2)peak) on a wheelchair ergometer. On a separate day, two 12-minute intermittent bouts consisting of three 4-minute stages were completed at individualized imposed power outputs equating to light (40% Vo(2)peak) and moderate (60% Vo(2)peak) intensity exercise. On a third occasion, participants were assigned to either the overall group or the peripheral group and were required to self-regulate 12-minute intermittent exercise according to either overall RPE or peripheral RPE reported during the corresponding imposed intensity trial.

SETTING

Laboratory facilities at a university.

PARTICIPANTS

Preliminary population of able-bodied participants with no prior experience of wheelchair propulsion (N=18).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Differences in oxygen consumption (Vo(2)), heart rate, blood lactate concentration, and power output between the imposed and self-regulated exercise trials.

RESULTS

No difference was found in physiological responses between the moderate-intensity imposed and RPE-regulated trials in the peripheral group, whereas a significant (P<.05) underproduction in Vo(2) (1.76±.31 vs 1.59±.25L/min) and blood lactate concentration (2.8±0.90 vs 2.21±.83mmol/L) was seen in the overall group. In contrast, a significant (P<.05) overproduction was seen in the peripheral group at a light exercise intensity, whereas no difference was found between all variables during the light-intensity imposed and RPE-regulated trials in the overall group.

CONCLUSIONS

Peripheral RPE enabled a more precise self-regulation during moderate-intensity wheelchair exercise in novice users. In contrast, overall RPE provided a more accurate stimulus when performing light-intensity propulsion.

Cardiovascular drift in trained paraplegic and able-bodied individuals during prolonged wheelchair exercise: effect of fluid replacement

The progressive heart rate (HR) increase and stroke volume (SV) decline during prolonged constant-load leg exercise signifies cardiovascular drift (CVdrift); fluid replacement is known to minimize this phenomenon. Like their able-bodied counterparts (AB), paraplegic athletes undergo prolonged exercise during training and competition, which could result in CVdrift. The aim of this study is to address the role of rehydration on preventing CVdrift in spinal cord injured (SCI) paraplegic athletes. Eight SCI athletes with an injury level between C7 and T6 and 9 AB subjects performed 60-min constant-load exercise on a wheelchair ergometer in a thermo-neutral environment. No fluid was taken in 1 trial, whereas 85% of sweat losses were replaced by drinking water in another trial. Cardic output (CO), SV, HR, and oral temperature (Tor) were determined during exercise. Prolonged exercise resulted in similar HR (18 beats·min(-1) for AB and 12 beats·min(-1) for SCI) and Tor (0.63 °C for AB and 0.71 °C for SCI) elevation and SV decline (-8.5 mL·beat(-1) for AB and -5.5 mL·beat(-1) for SCI), whereas CO remained unchanged. Water intake restrained the exercise-induced hyperthermia and resulted in smaller SV decline (-4.0 mL for AB and -3.0 mL for SCI, p < 0.01). In conclusion, CVdrift was similar in SCI and AB subjects during prolonged wheelchair exercise. Likewise, the beneficial effects of hydration in both groups were analogous.

Test-retest reliability and minimal detectable change of the SmartWheel clinical protocol

OBJECTIVES

(1) To quantify the intra- and intersession reliability and minimal detectable change (MDC) of the SmartWheel clinical protocol (SCP) and (2) to compare the reliability of the SCP between experienced and naïve wheelchair users.

DESIGN

Test-retest study.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Manual wheelchair users (WCUs) (n=10) with 1 to 32 years of wheeling experience and able-bodied (AB) naïve users (n=15).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Wheelchair propulsion parameters including average peak force, push frequency, push length, and velocity were measured according to the SCP but with 5 trials per session, for 2 sessions. WCUs and AB users were analyzed separately. Intraclass correlation coefficients ([ICC](2,1) and ICC(2,5)) were calculated to assess intrasession reliability. ICC(2,1) and MDC (with 95% confidence) were calculated for each SCP parameter using a single trial from each session and with the mean of 5 repeated measures to evaluate intersession reliability.

RESULTS

Intra- and intersession reliability for WCU parameters ranged from high to very high correlation (ICC range, .70-.99). For AB parameters, intrasession ICC(2,1) ranged from moderate to very high (ICC range, .50-.92), while intersession ICC(2,1) indicated low to very high correlation (ICC range, .25-.90). Estimates of standard error of measurement and MDC were provided for each parameter. For both WCUs and AB users, using the means from 5 trials increased intra- and intersession ICC and decreased MDC values. All MDC values were lower for WCUs compared with AB users.

CONCLUSIONS

The SCP is a reliable method for assessing propulsion parameters in WCUs, even if just 1 trial is taken per session. AB users showed lower intra- and intersession reliability compared with WCUs. Therefore, for AB users or individuals with minimal wheeling experience, averaging multiple trials is recommended for the SCP.

Supporting the paralympic athlete: focus on wheeled sports

The complexity of wheelchair sports provides the scientist with a unique challenge. There are two major components that contribute towards 'wheeled sports' performance: the athlete and the chair. It is the interaction of these two components that enable wheelchair propulsion and the sporting movements required within a given sport. This article will describe three discrete case studies on how sport scientists have worked with Great Britain coaches and practitioners to help optimise training leading to a major competition through evidence base practise. A fourth area will describe on-going work designed to address the optimisation of wheelchair configurations for wheelchair court sports. It will focus on four sports: wheelchair racing, wheelchair tennis, wheelchair basketball and wheelchair rugby. The first topic will discuss the concept of pushing economy and mechanical efficiency of wheelchair propulsion. The second topic will show how technology assists the coaching process. The third topic will illustrate the concept of sports classification, and show how training volume 'in terms of basketball shooting' may need to be individually assigned and finally future research within wheelchair team sports and chair configurations will be examined.

Physical capacity after 7 weeks of low-intensity wheelchair training

PURPOSE

To simulate the effect of low-intensity exercise in early rehabilitation, we investigated the effect of a 7-week low-intensity norm duration hand rim wheelchair training on the physical capacity in untrained able-bodied individuals.

METHOD

Twenty-five able-bodied participants were randomly assigned to an experimental and control group: 10 participants exercised 7 weeks, three times a week at 30% heart rate reserve (HRR) for 30 min (experimental group). The control group consisted of 15 participants who did not receive training. Physical capacity (maximal isometric strength, sprint power, peak power output and peak oxygen uptake) and submaximal performance [heart rate (HR), oxygen uptake (VO₂), mechanical efficiency (ME)] were assessed pre- and post-training. The levels of upper-body discomfort were determined with the use of a Local Perceived Discomfort scale.

RESULTS

Compared to the control group the experimental group significantly improved on sprint power (+31.2%), peak aerobic power output (+34%), submaximal HR, VO₂ and ME (+16.9%). The participants did not experience high levels of local discomfort in the upper body during the training.

CONCLUSIONS

Low-intensity norm duration hand rim wheelchair training which significantly improved peak aerobic and sprint power output, efficiency and physical strain in able-bodied untrained individuals. Training at 30% HRR (3 × /week, 30 min/session) may be appropriate in untrained individuals, such as novice wheelchair users at the start of their rehabilitation, to prevent early fatigue and overuse and enhance motivation.

Effects of 4-weeks of asynchronous hand-rim wheelchair practice on mechanical efficiency and timing

PURPOSE

To investigate the consequence on gross mechanical efficiency (GE), arm frequency and sub-maximal performance, of paced and unpaced practice during asynchronous hand-rim wheelchair propulsion.

METHODS

Twenty-five able-bodied participants performed five, 4-min exercise bouts at 1.7 m/s, at the freely chosen frequency (FCF) and four paced arm frequencies of 60, 80, 120 and 140% FCF. GE, arm frequency and measures of sub-maximal performance were determined. Participants were assigned to an unpaced (FCF, N = 9), paced (80% FCF, N = 8) or control (CON, N = 8) no practice group. The FCF and 80% FCF groups received 4-weeks (unpaced and paced, respectively) propulsion practice (three sessions·per wk, four 4 min/trials; 33-35 W) at 1.7 m/s on a wheelchair ergometer. Following practice, the pre-testing protocol was repeated.

RESULTS

Mean GE showed a relative increase in both experimental groups (21 and 17%; FCF and 80% FCF respectively; p = 0.001) compared to no change in CON (-1.5%). The FCF arm frequency decreased in both experimental groups (p = 0.001), with larger changes evident following FCF practice.

CONCLUSION

Four weeks of unpaced or paced practice had a beneficial effect on GE. This improvement seems to be associated with a reduction in arm frequency.