Browsing Kinesiology, Recreation, and Sport by Title
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Prevalence of Cardiac Abnormalities in Male and Female College Athletes when Exposed to Physiological and Thermal StressorsCardiovascular pre-participation screening of collegiate student athletes is inadequate. Physiological stress in the form of submaximal exercise and heat exposure can both alter cardiovascular function, possibly elucidating an abnormality via electrocardiogram (ECG). Purpose. To investigate prevalence of cardiac abnormalities in college athletes when exposed to physiological and thermal stress. Methods. Eleven participants (males n=5; females n=6; 20.5 ± 1.4 yrs; 167.8 ± 4.8 cm; 60.0 ± 4.5 kg; 56.1 ± 12.2 ml/kg/min) currently participating at the NCAA Division I level volunteered for this study. Participants completed two submaximal treadmill tests (70% of VO2 max) in varying environmental conditions: thermoneutral (24.8 ± 1.6˚C) and hyperthermic (38˚C) for 30 minutes. ECGs were recorded at five minute intervals. PR interval duration, ST segment elevation/depression, and R and S wave voltage amplitude were measured; ECGs were further analyzed for abnormalities. A repeated measures ANOVA was used to test the effects of condition by time.Results. No significant condition by time interactions were found for any variable (p>0.05). Significance across time manifested as a decreased PR interval (p<0.05), R wave voltage, (p<0.05), and S wave voltage (p<0.05). No main effects (p>0.05) were found for ECG abnormalities however; high occurrences of incomplete left bundle branch block (ILBBB) were found. Conclusion. Submaximal exercise in the hyperthermic condition did not significantly alter cardiovascular function in the parameters measured; however, the total number of ECG readings with abnormalities was higher in the hyperthermic condition compared to thermoneutral), most notable in incidences of ILBBB.
Relationship Between Foot Pressures and Alterations of Horizontal Velocities of the Center of Mass While HurdlingThis study analyzed the landing phase of hurdle clearance to investigate how the vertical displacement in the hurdler’s center of mass and foot pressures at ground contact lead to a change in the hurdler’s overall horizontal velocity of the center of mass. This study examined four male collegiate high hurdlers as they performed three trials of clearing one 42 inch high hurdle. The subjects were filmed during the three trials using three Panasonic cameras (60 Hz) and one JVC video camera (60 Hz), which was later used to provide video images in order to digitize each frame using the APAS software. The subjects’ foot pressure mapping data was also recorded at a sampling rate of 400 Hz during the three trials using the Tekscan high resolution (HR) Fscan hardware and software. The Tekscan HR Fscan hardware and software allowed for pressure measurements of the subjects’ forefoot, heel, and total foot pressure measured in pounds per square inch. The data collected from the APAS software and the Tekscan software was then calculated using the statistical software package SPSS. Multiple Pearson product correlations were analyzed between the kinematic and kinetic variables with one of these correlations resulting in a moderate relationship. The correlation between the change in the center of mass horizontal velocity and the heel pressure psi during the landing phase resulted in a moderate relationship with a correlation coefficient of r = .612, p= .034. The relationship between these two variables indicates that when a hurdler heel taps during the transitioning from flight phase to landing phase there is a decrease in their horizontal velocity.