Michel Dabonneville

A 5-min running field test as a measurement of maximal aerobic velocity

Abstract Based on a theoretical approach from world record running data, we have previously calculated that the most suitable duration for measuring maximal aero-bic velocity (vamax) by a field test was 5 min (vamax(5)). The aim of this study was, therefore, to check this hypothesis on 48 men of various levels of physical fitness by comparing (vmax(5)) with (vamax) determined at the last step of a progressive treadmill exercise test when the subject felt exhausted (vamax(t)) and during a test on a running track, behind a cyclist (following an established protocol) (vamax(c)). For each test, (O2max) was also measured by a direct method on a treadmill (O2max(t)) and calculated by an equation for field tests (O2max(5) and O2max(c)). The Vamax(5) [17.1 (SD 2.2) km · h−1] and (vamax(c)) [(18.2 (SD 2.4) km · h−1] were significantly higher than (vamx(t)) [16.9 (SD 2.6) km · h−1; P < 0.001]. The (vamax(t))␣was strongly correlated with (vamax(5)) (r␣= 0.94) and (vamax(c)) (r = 0.95) (P < 0.001). The best identity and correlation between (vamax(5)) and track performances were found in the runners (n = 9) with experience over a distance of 3,000 m. The O2max(5) and (O2max(c)) were higher than O2max(t) (+ 5.0% and + 13.7%, respectively; P < 0.001) and O2max(t) was highly correlated with vamax(5) (r = 0.90; P < 0.001). These results suggest that the 5-min field test, easy to apply, provided precise information on vamax and to a lesser degree on O2max.

Two-dimensional kinematic and dynamic analysis of a karate straight punch.

The mechanical effect of punches performed in martial arts or boxing sports has been studied on different ways: the impact force was either directly measured with sensors fixed on rigid frames [5, 6] or indirectly estimated from the mechanical features of materials broken during strike tests [2, 3]. A few authors developed experimental devices for measuring this force in actual fighting conditions [1] or on a punching bag [4]. Among the studies that analyzed the kinematics of the striking segments [2, 3, 5], only one [2] related kinematic and dynamic data through the linear momentum. According to this approach, a straight punch struck by a karateka (1.68 m, 68 kg, 3rd dan black belt) on a training instrument traditionally used in karate (makiwara) was analyzed in two dimensions. The peak force was two to three times lower than the maximum values (4000 to 6000 N) reported in previous studies [1, 5, 6], which could be explained by the makiwara flexibility. The large difference between the variation of the karatekas linear momentum and the linear impulse of the target-block pointed out the limitation of a 2-D analysis of this movement, which cannot take into account the angular momenta of the trunk and the upper limbs around the vertical axis.

A method for computing the actual trajectory followed by a manual wheelchair during real life propulsion

Until now, kinematics of actual wheelchair propulsion has only been studied during straight displacements with devices that allowed calculating the linear speed of the wheelchair Coutts (1990), Faupin et al. (2002), Moss et al. (2003) and Vanderthommen et al. (2002). For investigating wheelchair propulsion in real life conditions, an original wireless wheelchair ergometer (WWE) has been equipped with several dynamic and kinematic transducers Dabonneville et al.(2002). For instance, rotating potentiometers were fixed on rear wheels axles for measuring the angular positions of each wheel with respect to the wheelchair reference frame. This study presents a method for reconstructing the actual trajectory of the wheelchair from data recorded by potentiometers along a known curvilinear circuit.

Drag force mechanical power during a propulsion cycle on a manual wheelchair

In this case, Fb is measured by a “drag-test” where the subject is sitting upright on the wheelchair (van der Woude et al. 1986), and Vw is approximated by the average treadmill or roller velocity. Some authors, however, have shown that both wheelchair speed (Coutts 1990, Moss et al. 2005, de Saint Rémy 2005) and braking force (de Saint Rémy 2005, Sauret et al. 2006) were not constant along the propulsion cycle. These latter results let suppose that mechanical power of wheelchair propulsion should not be constant during the cycle. That hypothesis has been investigated and three calculation methods of drag force mechanical power have been compared in this study.

Computing wheelchair drag force from the system's total weight value and distribution

A 3-D surface equation was used to estimate changes of the resultant braking forces (F b ) during real life conditions of manual wheelchair locomotion from the weight of the system (W) and its relative fore-and-aft distribution (D) on the front castors due to the subject movement.

Fore-and-aft evolution of the subject's center of mass and center of pressure during actual wheelchair propulsion

The effort produced by a wheelchair user during propulsion on a horizontal floor mainly depends on the resulting braking force, which is related to the total mass of the system and its fore-and-aft distribution (de Saint Rémy and al, 2003). However, it is not easy to continuously measure this latter parameter during field locomotion. The aim of this study was to compare the displacements of the subject’s center of mass (COM) computed from a kinematic analysis of his movements while crossing a camera’s field of view, and those of his center of pressure (COP) calculated from the measurements of a six-component force-plate fixed under the seat of a wireless wheelchair ergometer (WWE) (Dabonneville and al, to be published), during actual wheelchair propulsion.