The highest jump was used for analysis. VJPP and VJMP were determined using equations from Johnson and Bahamonde (1996). After VJ testing was complete, participants rested for 5 min before performing 3 maximal 20 m sprints with 3 min of rest between sprints. Sprint times were recorded using a wireless selleck catalog TC-System (Brower Timing Systems, Draper, Utah, USA). Timing gates were set at 10 and 20 m so that both distances could be recorded simultaneously. Participants used a standing 2-point start position. The timing clock started when the subjects�� rear foot left the ground. All performance testing for session 2 was conducted in a large, open gymnasium with wooden floors. Participants attended a third and final session, during which they performed eight resisted sprints on a non-motorized treadmill (Force 3.
0, Woodway, Waukesha, WI, USA). Similar to session 2, this session was preceded by a dynamic warm-up involving calisthenics, submaximal walking, and submaximal jogging on the treadmill. Chia and Lim (2008) determined that peak power elicited during repeated sprints on non-motorized treadmills can be impacted by a rest period, and indicated that it is essential to use a minimum of 2 min rest between efforts to maintain a consistent peak power measurement. Therefore, 3 min of seated rest was given between sprints. Resisted sprints were performed with non-randomized increasing relative loads expressed as percent of body weight: 5, 10, 15, 20, 25, 30, 35, and 40 percent of body weight. Sprint peak power (SPP) was measured for each load to help determine which relative load elicited each participant��s greatest SPP.
On the rear shaft of the treadmill there is a speed sensor that directly measures the distance. The sensor is a digital encoder and the resolution is 2 cm per pulse. Pacer software digitally filters (at selected cut-off frequency) the distance/time data and then differentiates using the finite difference technique to produce velocity data. Pacer software digitally filters (at selected cut-off frequency) the distance/time data and then double differentiates using the finite difference technique to produce acceleration data. Pacer software calculates the product of the instantaneous velocity and horizontal force to determine the instantaneous power. Horizontal force is directly measured from the load cell connected to the user��s waist tether.
Vertical force is directly measured from the 4 load cells mounted under the running belt. An older version of the Woodway has previously been validated to be able to assess power (Lakomy, 1984). After SPP testing was complete, participants were given 5 min of seated rest before being tested for leg press 1 RM (LPMAX), leg press 1 RM relative to body weight (RELBW), leg press 1 RM relative to lean body mass (RELLBM), leg press AV-951 1 RM power (MAXPOW), and leg press power at 80% of 1 RM (LP80POW) using an Air300 Leg Press (Keiser, Fresno, CA, USA).