Effects of plyometrics performed during warm-up on 20 and 40 m sprint performance.

BACKGROUND: Postactivation potentiation in the form of a plyometric during warm-ups have been shown to improve performance in some speed/power events. This study aimed to determine if a plyometric during warm up can increase sprint performance in a 20 and 40 m sprint. METHODS: In this study we measured sprint times of 10 male track and field athletes over distances of 20 and 40 m after warm-ups with and without a plyometric exercise. The subjects performed the sprints at the same time on 2 different days, once with the experimental treatment, a plyometric exercise in the form of a plate jump, and once without. Plate jumps were chosen as the plyometric treatment because they do not require special equipment or facilities. The plate used for the plate jumps had a mass of 11.2 kilograms, which was between 12.8-16.6% of each athlete's body mass. RESULTS: Statistical analysis showed a decrease in sprint time when a plyometric was performed during the warm-up for both 20 (t-test P<0.05) and 40 m sprints (t-test P<0.01). The effect sizes of the improvement for both the 20 and 40 m sprints were d=0.459 and d=0.405, respectively, which is considered a small to medium effect. CONCLUSIONS: These results indicate that including a plyometric exercise during warm-ups can improve sprint performance in collegiate aged male sprinters during short sprints.

Effect of walking speed on typing performance using an active workstation.

This study tested the effect of treadmill walking speed on typing performance when these tasks were performed simultaneously. 24 research participants (M age = 23.2 yr.) performed a typing test under each of four conditions including the control (seated), treadmill walking at 1.3 km/hr., 2.25 km/hr., and 3.2 km/hr. Results indicated that treadmill walking had a detrimental effect on typing performance, but that the walking speed of 2.25 km/hr. would result in better typing performance than the slower and faster speeds. Seated typing was better than typing while walking at 1.3 km/hr. and typing while walking at 3.2 km/hr. Typing performance while walking at 2.25 km/hr. was not different than seated typing performance. The results support the potential of treadmill walking at 2.25 km/hr. to provide low-intensity physical activity without compromising typing performance.