Joeri Verellen

Physical fitness profile of elite athletes with intellectual disability

The aim of this study was to investigate the physical fitness profile of high‐performance athletes with intellectual disability (ID) in comparison with able‐bodied individuals.

Influence of crank rate in hand cycling

PURPOSE The purpose of this study was to determine gross mechanical efficiency (ME) at different power output (PO) levels of synchronous hand cycling and to evaluate the influence of increasing PO by changing crank rate or resistance in wheelchair users with experience in hand cycling. METHODS Nine male participants with spinal cord injury randomly performed three maximal incremental hand cycling tests using a computer controlled cycle ergometer. Each test started at a PO level of 50 W with increments of 10 W. In the velocity protocol, PO was increased via crank rate while resistance was constant (VEL). In the resistance protocol PO was increased via resistance while crank rate was constant (RES). In the freely chosen frequency protocol, the participants could freely select their crank rate while resistance was automatically adjusted to obtain the desired PO (FCF). RESULTS Peak physiological responses were similar in all three tests, whereas PO max was lower in VEL compared with RES and FCF. Similar values for gross ME were found in both RES and FCF protocols, although systematically higher and increasing crank rates were adopted throughout FCF. Nevertheless, differences in gross ME at comparable relative (RES > VEL at 60 and 80% of PO range: 14.09 and 14.40% vs 13.02 and 13.11%, respectively) and absolute (RES, FCF > VEL at 90 W: 14.47, 14.47, and 13.43%, respectively) PO levels were demonstrated. CONCLUSION These results suggest that during synchronous hand cycling the freely chosen crank rate is not necessarily the most economical, that high crank rates result in a lower ME at a given PO and that freely chosen crank rates increase with increasing PO levels.

Cardiorespiratory responses during arm ergometry, functional electrical stimulation cycling, and two hybrid exercise conditions in spinal cord injured

Purpose. The purpose of this study was to compare peak functional aerobic power (VO2 peak) across four different types of exercise: arm crank ergometry (ACE), functional electrical stimulation (FES) cycling, and two hybrid exercise conditions: FES cycling combined with ACE and FES rowing using a newly developed rowing device (ROWSTIM). Methods. Five participants (C7 – T12), four male paraplegics with neurologically complete spinal cord injury (SCI), and one male with neurologically incomplete SCI, underwent a progressive maximal peak oxygen exercise test to ascertain peak physical work capacity during arm cranking, FES cycling, FES cycling combined with arm cranking and FES rowing. Results. Metabolic variables were significantly lower for FES cycling versus ACE, FES cycling combined with ACE and FES rowing measures (P < 0.05). However there were no significant differences between ACE, FES cycling combined with ACE and FES rowing. Conclusions. Preliminary results suggest that the ROWSTIM is as effective an exercise device or training tool for persons with SCI as ACE or combined FES-cycling and ACE, and more effective than FES-cycling. A larger sample size and further technological developments of the ROWSTIM are needed to demonstrate the efficacy of rowing over other hybrid exercise modalities and ACE.

Towards evidence-based classification in wheelchair sports: Impact of seating position on wheelchair acceleration

Abstract In most Paralympic wheelchair sports, active trunk range of movement is assessed by observing shoulder girdle excursion during active trunk movements and is a key determinant of an athletes class. However, to date research evaluating the impact of reduced trunk range of movement on wheelchair sports performance has not been conducted. In the present study, 15 non-disabled male participants performed two 20-s sprints on a wheelchair ergometer in each of three seating positions. Positions were typical of those used to enhance sitting stability in wheelchair sport and each impacted available trunk range of movement differently: condition-90 (seated with thighs horizontal; unrestricted range of movement) condition-45 (seated with thighs in 45°), and condition-0 (seated with hips maximally flexed; minimum range of movement). In condition-90, the trunk only actively contributed to the first push; for the remainder of the sprint, the trunk was held almost isometrically at 48.2° to the horizontal (range 42.1–56.4°). Similar patterns were observed for both condition-45 and condition-0. Compared with condition-90, participants in condition-0 had reduced capacity to accelerate of statistical (P < 0.05) and practical significance. These findings are an important initial step towards evidence-based decision making in classification. Future research should evaluate the individual and collective impact of other factors that affect the trunks contribution to wheelchair sports performance, including strapping, seating position, and impairments of trunk muscle power and coordination.

Trunk strength effect on track wheelchair start: implications for classification.

PURPOSE The T54 wheelchair racing class comprises athletes with normal arm muscle strength and trunk strength ranging from partial to normal. Paralympic sports classes should comprise athletes who have impairments that cause a comparable degree of activity limitation. On the basis of this criterion, the purpose of this study was to determine whether the T54 class is valid by assessing the strength of association between trunk strength and wheelchair acceleration. METHODS Participants were 10 male and 3 female international wheelchair track athletes with normal arm strength. Six were clinically assessed as having normal trunk strength, and seven had impaired trunk strength. Measures included isometric arm and trunk strength and distance covered at 1, 2, and 3 s in an explosive start from standstill on a regulation track, as well as on a custom-built ergometer with four times normal rolling resistance. RESULTS No significant differences were observed between male athletes with and without full trunk strength in distance covered after 1, 2, and 3 s. Correlations between isometric trunk strength and wheelchair track acceleration were nonsignificant and low (0.27-0.32), accounting for only 7%-10% of variance in performance. Correlations between trunk strength and distance pushed under high resistance were also nonsignificant, although values were almost double (r = 0.41-0.54), accounting for 18%-28% of the variance in performance. CONCLUSIONS These results provide evidence that impairment of trunk strength has minimal effect on wheelchair acceleration and indicate the T54 class is valid. Results do not infer that athletes with no trunk strength should compete with those who have partial or full trunk strength.

Determinants of shuttle run performance in the prediction of peak VO2 in wheelchair users

Purpose. The purpose of this study was to determine the impact of ergonomic and environmental variations on indoor shuttle run (SR) performance in wheelchair sportsmen. Methods. Eleven experienced male wheelchair sportsmen performed three 25-m SRs in random order with varying turning capacity (TC) and mechanical resistance (MR): condition NN where participants used their sports wheelchair on a tartan surface, condition RN with increased MR, and condition RD with limited TC. Metabolic data were continuously recorded using a portable K4b2 system. Results. Friedman ANOVA with Wilcoxon a posteriori testing indicated similar VO2peak values in all three tests. SR performance, however, was significantly different across the three test conditions (NN: 536.18 ± 119.09 s; RN: 488.82 ± 119.84 s; RD: 404.91 ± 88.41 s). SR performance contributed for 28% of the explained variance of the measured VO2peak. The addition of TC or MR or both increased the explained variance to 32, 38 and 41%, respectively. Conclusions. These findings demonstrate a significant impact of variations in floor surface and wheelchair-user interface on SR performance. The findings also suggest that strong reservations have to be made regarding the validity of a SR test, as predictor of VO2peak in a wheelchair user population.

Peak and submaximal steady-state metabolic and cardiorespiratory responses during arm-powered and arm-trunk-powered handbike ergometry in able-bodied participants

The purpose of this study was to compare the peak and submaximal metabolic and cardiorespiratory responses during steady-state arm-powered (AP) and arm-trunk-powered (ATP) handbike ergometry. Twelve male able-bodied participants with no prior experience in handcycling completed a maximal progressive incremental test and a series of 6-minute submaximal tests at 130 W with various cadences in a custom-designed handbike ergometer that allowed a realistic simulation of AP and ATP handcycling. Peak power output, peak oxygen uptake, and peak ventilation were significantly lower, whereas peak blood lactate concentration was significantly higher during AP handcycling. Mean gross mechanical efficiency was significantly higher during AP handcycling (range 16.7 to 20.5%) compared with ATP handcycling (range 15.8 to 17.6%). These results suggest that AP handcycling is advantageous during submaximal steady-state handcycling, whereas ATP handcycling allows for a higher peak power output generation. However, it remains unclear which handbike configuration would be favorable during competition.

Development and application of a handbike ergometer to measure the 3D force generation pattern during arm crank propulsion in realistic handcycling conditions

The majority of investigations in hand cycling thus far were carried out in little realistic conditions, particularly with regard to ergonomics and mechanical characteristics such as steering and stabilization mechanisms. In addition, integrated investigations studying both the physiological and biomechanical responses during realistic maximal and submaximal hand cycling have not yet been conducted. This paper illustrates the design, the working, and the possibilities of a newly developed handbike ergometer that simulates hand cycling in realistic ergonomic and mechanical conditions with a continuous control of the workload. Built-in force transducers in both crank handles allow the registration of the orthogonal force components in three dimensions along a pre-defined X, Y, and Z-axes in function of time and/or position. Consequently, the resultant force and the forces exerted in each plane of the test person can be calculated to evaluate the forward, upward, and sideward force generation during hand cycling. The tangential, radial, and transversal forces can also be calculated to analyze the movement effectiveness. As well, eight extra channels are foreseen to allow a simultaneous and synchronized electromyography registration. The handbike ergometer is therefore a useful tool to capture data that are novel and at the forefront of the field of biomechanical analyses in hand cycling, taking into consideration the physical potential of the user, the configuration of the handbike and the handbike–user interface.