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Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains v, 84 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 43-47).

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

The purpose of this study was to measure the intensity and duration of ice hockey play for six university hockey players (three forwards and three defencemen) and to compare them with the results to a similar study published in 1976. Comparisons of heart rate output and time-motion characteristics between forwards and defencemen were examined as well as differences in intensity between practices and games. The players performed at significantly lower intensity, had less playing time per shift, and had less playing time per game than the players in the 1976 study. Both investigations had similar bench times between shifts. The forwards had significantly different time-motion characteristics from the defencemen but similar playing time intensity. The intensity of games was higher than practices in terms of on-ice intensity but similar in terms of total time above a threshold intensity ($ geq$ 70% of HRmax).

The evidence for an increase in resting vagal tone to explain the lower heart rate of endurance athletes remains controversial. This study used spectral analysis of heart rate (HRV) and blood pressure (BPV) variability to examine the vagal and sympathovagal influences on the sinus node in 12 endurance-trained athletes (A) and 10 age and sex-matched control subjects (C) (age: 26(1.2) yrs; VO2max: A: 68.2(2.1) vs C: 41.4(2.0) ml/kg/min; p $<$ 0.05). Continuous ECG and BP recordings were obtained during supine rest, sitting, controlled respiration (12 breaths/min), standing, exercise at heart rates of 100 and 130 beats/min, and after 5 and 15 minutes of seated recovery. No differences were observed between A and C in the vagal or high frequency (HF) components (48.0(4.0) vs 44.2(6.9) nu), in the low frequency (LF) components (55.8(6.9) vs 52.0(4.0) nu), or in the LF/HF ratios (1.72(0.4) vs 1.22(0.2)) of the HRV spectral components at rest or other experimental conditions, despite the lower resting heart rates of the A (53.1(1.8) vs 65.1(2.1) beats/min; p $<$ 0.05). Standing and exercise decreased the HF components and increased the LF/HF ratios similarily in both the A and C, controlled respiration induced similar rises in the HF component of HRV. Despite a significantly higher systolic BP in athletes, no difference was observed between A and C in the HF or LF components of either systolic or diastolic BPV. Exercise induced an increase in the HF component of BPV which was associated with the rise in breathing frequency. These results indicate a similar sinoatrial sympathovagal balance in A and C suggesting that training-induced bradycardia could result from an adaptation in the intrinsic sinoatrial properties. Also, endurance training does not appear to influence the beat-to-beat BPV.

A comparison of heart rate viability and respiratory sinus arrhythmia (RSA) characteristics was performed in 20 athletes and 12 age-matched sedentary controls (CTRL) (22 +/- 2.4 yrs). More specifically, this study examined the role of regular physical activity on the breathing frequency (BF)---RSA amplitude response curve comparing varsity swimmers (SW) to endurance runners (RU) to test the hypothesis that a locomotor-respiratory entrainment resulting from the water-immersion breathing pattern of swimmers would alter their respiratory related cardiac vagal integrative response. Spectral power components of HRV were computed from R-R interval sequences. Five-minute recordings were performed with subjects breathing either at their spontaneous breathing rate, at four breathing cycles less (M4) and four cycles more (P4) than spontaneous. Amplitude and phase of RSA were computed from the sinusoid fitted to the instantaneous heart rate within each breath while the gain of the RSA response was obtained from the slope of the RSA amplitude versus BF. (Abstract shortened by UMI.)

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This study investigated differences in heart rate recovery (HRR) and the underlying autonomic mechanisms following maximal and submaximal exercise between boys and men. Children are known to have a faster HRR than adults. However, the mechanism responsible for these differences is still largely unknown, but is thought to be due to differences in the autonomic nervous system. Ten boys (10.1 ± 0.8 years old) and ten men (24.2 ± 1.3 years old) completed a supine recovery following a maximal and submaximal exercise bout. HRR was measured as the decline in HR during the first minute of recovery and heart rate variability (HRV) was used to measure autonomic function. Boys had a faster HRR during the first minute of recovery from maximal exercise (p<0.05), but there was no difference in HRR following submaximal exercise (p>0.05). The R-R coefficient of variation and high frequency power were both significantly greater following maximal exercise in boys than men. There were no differences in HRV variables following submaximal exercise. These findings suggest that faster parasympathetic re-activation could be a mechanism responsible for faster HRR in boys compared to men, especially following maximal exercise. / School of Physical Education, Sport, and Exercise Science

Purpose: Little is known about the heart rate (HR) responses at the onset of exercise, at peak exercise, and recovery in apparently healthy men and women. The purpose of this study was to determine the prevalence of abnormal HR acceleration at the onset of exercise, define the HR acceleration profile, determine if traditional cardiovascular disease (CVD) risk factors are associated with abnormal HR acceleration, and identify whether abnormal chronotropic responses cluster with abnormal HR acceleration in an asymptomatic, self-referred, adult population. Methods: A retrospective examination of a symptom-limited maximal treadmill test was performed for participants of a university-based fitness program between 1990 and 2006. Records were analyzed for various HR responses from individuals (N=947) of both sexes who represented a broad range of age and fitness levels (mean VO2: 32.9±9.4ml∙kg-1∙min-1). Abnormal HR acceleration at minute 1 and ⅓ total exercise time was defined as a HR increase from standing rest of ≤14 and ≤28 beats respectively. Results: The prevalence of abnormal HR acceleration at minute 1 and ⅓ total exercise time was 30.6% and 31.3% respectively. The mean HR increase during the first minute and ⅓ total exercise time was 20.5 ± 10.3 and 33.7 ± 10.4 beats respectively. Abnormal accelerators had a significantly better CVD risk factor profile (lower systolic and diastolic blood pressure, BMI, total cholesterol, triglycerides, higher VO2, and higher percent of regular exercise) than normal accelerators, despite consisting of a greater percentage of current smokers. Lastly, abnormal HR acceleration showed higher prevalence with abnormal HR recovery than with chronotropic incompetence. Conclusions: In the present study cohort, a lower HR increase at the onset of exercise was associated with a better CVD risk factor profile but the same differences were not seen at ⅓ total exercise time. / School of Physical Education, Sport, and Exercise Science