Zeroing of six-component handrim dynamometer for biomechanical studies of manual wheelchair locomotion.

A six-component handrim dynamometer (HRD) is a dynamometer that rotates around the wheel axle during measurements. For this kind of dynamometer, static zero level calibration is insufficient because the proportion of the forces (i.e. handrim weight and centrifugal force) measured by each sensor varies according to the angular position and velocity of the dynamometer. The dynamic calibration presented in this paper is based on the direct correction of the sensor signals using Fourier's polynomials that take into account the influences of both the handrim weight distribution on the sensors with respect to the wheel's angular position and the effect of the wheel's angular velocity. When these corrections were applied to the signals produced by the sensors while the HRD was rotating and no effort was being exerted on the handrim, the calculated forces and torques remained close to zero, as expected. Based on these results, the wheel dynamometer can be confidently used for studying manual wheelchair locomotion under various real conditions. The method could also be applied in other situations in which a dynamometer rotates during measurements.

The effect of feet position on orthostatic posture in a female sample group.

Until now, the feet position effect on orthostatic posture has been investigated only in male or mixed sample groups. However, literature reports gender differences on orthostatic equilibrium. In order to study the effect of feet position on females and to complete the previous works, we tested a homogenous female sample group with 16 feet positions. Most of our results are in agreement with those already observed in male or mixed sample groups. The increase of the base of support induces an improvement of the orthostatic balance mainly on the medio-lateral axis. The stabilizing effect of the inner feet distance increase is more important than the one of the angle. We also noticed that the mean center of pressure position is located on the subjects' right side.

The 5 min running field test: test and retest reliability on trained men and women.

The repeatability of the maximal aerobic velocity ( v(amax)) estimated using the 5 min running field test (5(RFT)) has been examined in an heterogeneous population of 132 subjects distributed in five groups considering their sporting activities, their competition levels and their physical fitness levels: among them were national and local runners, rugby players, and multi-sport women and men. To establish the test and retest reliability, all the subjects took part in the 5(RFT) twice within 3 weeks. After the normality of distributions had been assessed using a Kolmogorov-Smirnov's test, a Student's paired t-test showed no difference between the two trials in all groups except that of the national runners. A heterogeneous group was then constituted from the other subjects, and this took part in the reliability study. Intraclass correlation coefficients calculated from a one-way ANOVA on the performances achieved by each group in both tests ranged from 0.94 to 0.98. The standard errors of measurement (SEM) of the 5(RFT) ranged from 0.95% (13 m) to 1.89% (20 m), which correspond to errors of 0.15 km.h(-1) and 0.34 km.h(-1) in the v(amax), respectively. These results indicate that the 5(RFT) is reliable when used in homogeneous groups with various characteristics as well as in a heterogeneous population. Moreover, the results of this study have shown that the 5(RFT) is reliable for estimating v(amax) from only one trial, since the intraclass correlation coefficients for one trial ranged from 0.88 to 0.96, which is of particular interest to coaches. Nevertheless, further studies would be necessary to evaluate the repeatability of this test in other populations such as school children and adults of both sexes having different characteristics.