Cardiovascular drift relative to ventilatory threshold in boys and men

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dc.contributor.advisor Mahon, Anthony D. en_US Cheatham, Christopher C. en_US 2011-06-03T19:37:47Z 2011-06-03T19:37:47Z 1997 en_US 1997
dc.identifier LD2489.Z78 1997 .C48 en_US
dc.description.abstract Cardiovascular drift can occur during prolonged exercise and is characterized by a gradual decrease in stroke volume (SV) and a corresponding increase in heart rate (HR) over time, despite the maintenance of a constant level of work; cardiac output (CO) usually is unchanged. A number of factors may cause cardiovascular drift to occur, including increases in peripheral blood flow, decreases in plasma volume, increases in circulating catecholamines, and metabolic acidosis. These physiological events may be influenced by the relationship of the exercise intensity to ventilatory threshold (VT). Therefore, the purpose of this study was to examine the cardiovascular responses during prolonged exercise in boys and men at an intensity set relative to VT. Eight boys (10-13 yrs.) and 10 men (18-25 yrs.) completed an orientation trial, a graded maximal exercise test, and a 40 minute submaximal exercise bout at an intensity equal to the V02 at VT. During the 40 minute exercise bout, V02 increased significantly over time (P_<0.05),although the magnitude of change was similar in boys and men (P>0.05). Heart rate was higher and SV was lower in the boys compared to the men (P<_0.05), and the changes in HR and SV were significant over time. Although there was a trend for the HR increase and SV decrease to be greater in the men, the group-by-time interaction was not significant. Cardiac output and arteriovenous oxygen difference were higher in the men compared to the boys (P<0.05), but remained constant over time. Mean arterial blood pressure (MABP) was higher in the men than the boys (P<_0.05). In the men, MABP decreased significantly from 10 to 40 minutes, while in the boys, MABP decreased (P<_0.05) from 10 to 30 minutes and then increased to a value similar to that at 10 minutes. This differential response in MABP over time resulted in a significant groupby-time interaction. Total peripheral resistance was significantly higher in the boys than the men, but remained constant over time (P>0.05). Men exhibited a greater decrease in plasma volume from 0 to 40 minutes. There was no group difference in perceived exertion (RPE) between the boys and the men, although the boys exhibited a greater increase in RPE over time than the men (P<0.05). In conclusion, the cardiovascular responses during prolonged exercise are similar in boys and men, although there is a tendency for the magnitude of cardiovascular drift to be greater in the men. In addition, due to the fact that these results are similar to previous studies not accounting for individual differences in VT, it would seem that these differences in VT should not be of concern when studying the cardiovascular responses during prolonged exercise.
dc.description.sponsorship School of Physical Education
dc.format.extent x, 80 leaves : ill. ; 28 cm. en_US
dc.source Virtual Press en_US
dc.subject.lcsh Cardiac output -- Measurement. en_US
dc.subject.lcsh Respiration -- Measurement. en_US
dc.subject.lcsh Exercise for men -- Physiological aspects. en_US
dc.subject.lcsh Exercise for children -- Physiological aspects. en_US
dc.subject.lcsh Heart beat. en_US
dc.title Cardiovascular drift relative to ventilatory threshold in boys and men en_US Thesis (M.S.)
dc.identifier.cardcat-url en_US

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  • Master's Theses [5293]
    Master's theses submitted to the Graduate School by Ball State University master's degree candidates in partial fulfillment of degree requirements.

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