Fdr x3000

A video camera (Sony FDR-X3000, Japan) synchronised with the mechanical apparatus recorded the swimmers in the sagittal plane to identify the entry and exit of the hand in the water. The string of a mechanical speedometer (SpeedRT, ApLab, Rome, Italy) was attached to the swimmers' waist (Dadashi et al., 2012) (link). The speedometer calculated the swimmer's displacement and velocity at a rate of 100 Hz and transferred data to a PC. Subsequently, the velocity-time series were imported into a signal processing software (AcqKnowledge v. 3.9.0, Biopac Systems, Santa Barbara, USA). Signal was handled with a Butterworth 4 th order low-pass filter (cut-off: 5 Hz) upon residual analysis. Swimming velocity (in m•s -1 ) was obtained from the software during three consecutive stroke cycles. Afterwards, the dv (in %) of each stroke cycle was computed as the CV, as previously mentioned (Barbosa et al., 2005) (link). Figure 1 presents the filtered swimming velocity for the three groups. Specifically, for each group, it shows the average of the 10 swimmers, being each of them represented by the mean of three consecutive stroke cycles. The beginning and end of each stroke cycle was considered the consecutive entry of the left hand into the water.

For the all-out testing, the string of a mechanical apparatus (SpeedRT, APLab) was attached to the swimmers' waist. 18 The speedometer calculated the displacement and speed of the swimmer at a rate of 100 Hz. Afterward, the speed-time data were imported into a signal processing software (AcqKnowledge, version 3.9.0, Biopac Systems). The signals were handled with Butterworth fourth-order low-pass filter (cut-off: 5 Hz). A video camera (Sony FDR-X3000) recorded the swimmers in the sagittal plane to identify the entry and exit of the hand and was synchronized with the speed-time data.
The following kinematic variables were collected during 3 consecutive stroke cycles over the middle 10 m to neglect the pushoff effect. Swimming speed (v, m/s) was obtained from the speedtime curve. The stroke frequency (SF, Hz) was calculated by the number of cycles per unit of time (based on the footage recorded) from the time it took to complete one full cycle (f = 1/P; where P is the period) and afterward converted to Hz. The intracyclic variation of swimming speed (dv, %) was computed as being the coefficient of variation (CV): CV = mean/1SD × 100.