Relationship between proxies for Type II fiber type and resting blood pressure in Division I American Football Athletes.

OBJECTIVE: The risk for cardiovascular disease is well-documented. Perhaps surprisingly, specific athletic populations, including American football players, exhibit increased risk for cardiovascular disease as presented by elevated blood pressure. There is evidence suggesting a link between muscle fiber type distribution and resting blood pressure. Acknowledging this association, it becomes important to clarify an individual's risk for developing cardiovascular disease later in adulthood. The purpose of this study was to assess football performance measures-in particular proxies for muscular power-and their effect on resting blood pressure in football athletes. METHODS: A total of 80 collegiate-level football players participated in this study. Each participant's body fat %, body mass index, waist circumference, and mean arterial pressure (MAP) were measured. Participants performed one-repetition maximums of bench press, back squat, 40-yard dash, and vertical leap, and a power index (PI) defined as the product of vertical leap and mass. Linear regressions were run between body composition variables and performance measures for all players and a subset of skill players only. RESULTS: The PI was found to be positively, significantly correlated with MAP in all players (r = 0.269; P = 0.035) and the skill players subset (r = 0.425; P = 0.004). CONCLUSION: The results of the present study indicate an association between muscle fiber type distribution, as indicated by muscular power capacity, and resting blood pressure.

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.

The acute effects of static stretching on the sprint performance of collegiate men in the 60- and 100-m dash after a dynamic warm-up.

Previous research has shown that static stretching has an inhibitory effect on sprinting performances up to 50 m. The purpose of this study was to see what would happen to these effects at longer distances such as those seen in competition. This study used a within-subjects design to investigate the effects of passive static stretching vs. no stretching on the 60- and 100-m sprint performance of college track athletes after a dynamic warm-up. Eighteen male subjects completed both the static stretching and the no stretching conditions in counterbalanced order across 2 days of testing. On each day, all subjects first completed a generalized dynamic warm-up routine that included a self-paced 800-m run, followed by a series of dynamic movements, sprint, and hurdle drills. At the end of this generalized warm-up, athletes were assigned to either a static stretching or a no-stretching condition. They then immediately performed 2 100-m trials with timing gates set up at 20, 40, 60, and 100 m. Results revealed a significant slowing in performance with static stretching (p < 0.039) in the second 20 (20-40) m of the sprint trials. After the first 40 m, static stretching exhibited no additional inhibition of performance in a 100-m sprint. However, although there was no additional time loss, athletes never gained back the time that was originally lost in the first portion of the trials. Therefore, in strict terms of performance, it seems harmful to include static stretching in the warm-up protocol of collegiate male sprinters in distances up to 100 m.