Effect of push frequency and strategy variations on economy and perceived exertion during wheelchair propulsion
Department of Exercise and Sport Science, Manchester Metropolitan University, Manchester, England, United Kingdom Arbeitsphysiologie
(Impact Factor: 2.19).
10/2003; 90(1-2):154-8. DOI: 10.1007/s00421-003-0875-6
Wheelchair locomotion is a cyclical activity and participants are free to select any push frequency-propulsion strategy combination that suits their needs at a given power output. The aim of the study was to examine the physiological effects of varying push frequency and strategy on pushing economy. Twelve male, able-bodied participants completed four, randomly assigned, 5-min bouts of submaximal exercise at 32 W on a wheelchair ergometer. Each bout of exercise combined two different push frequencies (40 and 70 push min(-1)), with one of two different push strategies [synchronous (SYN): both arms pushing together, and asynchronous: one arm applying force to the wheel at a time). Physiological measures included oxygen uptake ( VO(2)), heart rate (HR) and blood lactate [La](b )concentration. Differentiated ratings of perceived exertion (RPE) were also recorded (overall, local and central). Separate ANOVA were used for VO(2), HR, [La](b) and RPE as the dependent variables. Where significant differences were identified, a Bonferroni post hoc test was used. The main effect for push frequency by strategy was significant for VO(2) ( P<0.01). Scrutiny of the HR values showed that the SYN 40 condition was significantly less stressful than all other frequency-strategy combinations ( P<0.01). RPE data supported these findings although they were found to be non-significant. When looking at [La](b,) both of the main effects were also significant showing the concentration was lower on average when the push rate was 40 as opposed to 70 (1.65 vs 2.14 mmol l(-1); P<0.01). This study provides further evidence that a low push frequency provides the most economical form of wheelchair propulsion especially when combined with a SYN strategy.
Available from: Paul Calmels
- "C Les contraintes fonctionnelles pour la recherche d'une autonomie maximale induisent une dépense énergétique importante pour effectuer certains actes de la vie quotidienne et maintenir un niveau de vie active (les exercices de verticalisation, de transfert, les actes quotidiens sont sources d'une grande dépense énergétique)        ; C de plus, l'état de santé, le bien être, l'autonomie et la prévention des pathologies liées à la perte d'activité et à la sédentarité (surcharge pondérale, douleur etc.), sont corrélés avec une pratique régulière d'activité physique           . • des justifications personnalisées : C selon l'état antérieur du sujet : en particulier selon son niveau d'adaptation à l'effort, qui conditionne l'importance du réentraînement (il devra être d'autant plus important chez le sujet ayant peu pratiqué d'activité phy- sique) ; C selon l'âge du sujet : le réentraînement ne doit pas être négligé chez le sujet âgé car il conditionne aussi les possibilités fonctionnelles (conservation de la propulsion en fauteuil roulant qui constitue un élément de l'auto- nomie) ; C selon le mode ou le choix de vie : en particulier, le souhait d'une vie active, d'une reprise d'une activité professionnelle ou d'un sport va justifier un programme de réentraînement et son niveau d'intensité ; C les possibilités de choix du fauteuil roulant vont contraindre à une personnalisation de l'entraînement (amélioration des capacités cardio-vasculaires, adaptation , réglages et apprentissage des paramètres biomécaniques sollicités par la propulsion)        . "
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ABSTRACT: Introduction. – Individualised exercise training programs in spinal cord injury (SCI) individuals are considered highly effective for improving and maintaining capacity for physical activity, as well as for reducing cardiovascular risk. However, no consensus exists on the type, intensity, and frequency of the training programs for SCI.Objective. – To review the literature about training program characteristics for SCI and describe their efficacy, limits, and results, with the aim of proposing specific recommendations.Methods. – Query using Medline and Embase databases. Ninety-nine references were found, including the following: Clinical studies examining physical endurance capacity of individuals with SCI, physiological responses to maximal exercise, or cardiovascular differences between sedentary and wheelchair-trained subjects; Articles? investigating the effects of training programmes for SCI.Results. – Various combinations of training intensity, duration, frequency, type, and ergometers have been proposed for SCI. Whatever the characteristics of the training program, a review of 25 cardiorespiratory training studies involving SCI subjects revealed an average improvement of 9% to 99% in VO2max, 19% to 118% in power output, and a decrease in submaximal values after 4 to 36 weeks of training.Discussion – Conclusion. – Wheelchair ergometers seems to be interesting for SCI because it mimics closely the daily motor tasks of wheelchair users and allows for adjustment of the wheelchair. Both continuous and interval training programmes are appropriate, but intermittent exercise intensities may be more beneficial since they mimic the intermittent nature of daily activity patterns. Furthermore, on the basis of the results of these studies, we recommend that training at or above 70% of maximum heart rate, for 30 minutes of rhythmic exercise, three days per week during eight weeks, will provide a sound of basis for design of an endurance exercise programme for people with SCI.
Annales de Réadaptation et de Médecine Physique 06/2005; 48(5):259-269. DOI:10.1016/j.annrmp.2004.12.004
Available from: Andrew D. Moss
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ABSTRACT: Full-text of this article is not available in this e-prints service. This article was originally published following peer-review in Adapted Physical Activity Quarterly, published by and copyright Human Kinetics. To compare the velocity characteristics of wheelchair propulsion with and without the use of a tennis racquet, eight male wheelchair tennis players performed a series of 20m sprints from a stationary start. The maximum velocities reached on average 4.39 ± 0.74 m/s; however, they were reduced by 0.18 ± 0.06 m/s during the racquet condition. Furthermore, when wheeling under the racquet condition, the velocities achieved during the first three pushes were significantly reduced. The reduction in maximum velocity and relative velocity contributions while holding a tennis racquet may have been due to an ineffective push technique resulting in low effectiveness of force application. The relation of these parameters and trunk stability is discussed.
Adapted physical activity quarterly: APAQ 07/2005; 22(3). · 1.32 Impact Factor
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ABSTRACT: Diamond and AlN are, respectively, the non-piezoelectric and piezoelectric materials showing the highest acoustic velocities. So, SAW devices based on AlN/diamond are a promising candidate to operate at the highest frequencies. In this work we analyze both theoretically and experimentally the propagation along this structure of the 0th and 1st SAW modes and of the 1st PSAW mode. The phase velocity and leaky propagation loss were calculated vs. AlN film thickness h, normalized to the acoustic wavelength λ, for different electrical boundary conditions at the AlN surfaces. For AlN/diamond, two different low-loss PSAW conditions have been observed in the 1st PSAW mode at h/λ, ≈ 0.09 and 0.15, where the leaky loss is below 0.001 dB/λ, i.e. it is possible that fast PSAWs degenerate into SAWs, at these points. The corresponding velocities are ≈ 15.9 and 13.4 km/s. Experiments on both SAW and low-loss PSAW propagation have been done using the same delay line configuration on AlN/diamond, at different AlN thickness. A good accordance between experimental data and theoretical predictions was observed for both phase and group velocities.
Ultrasonics Symposium, 2005 IEEE; 10/2005
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