Biomedical subjects

S H Boutcher

Publications and source records attributed to S H Boutcher.

At least 19 recordsLinked to original sources

PubMed2006

Impact of moderate overweight and body composition on postexercise hemodynamic responses in healthy men.

Postexercise hypotension (PEH) is a well-established phenomenon that may contribute to the antihypertensive mechanisms of exercise. The purpose of this study was to examine the impact of moderate overweight on postexercise hemodynamic responses in a group of healthy nonobese men (n = 16, aged 20.4+/-1.8 years) with apparently normal cardiovascular function at rest. Forearm blood flow, using strain gauge plethysmography, blood pressure, using a Finapres device, and cardiac output (CO), using impedance cardiography, were measured on a control day and on a separate day following a bout of moderate intensity exercise (20 min at 75% heart rate reserve). Linear regression analysis, adjusted for exercise intensity, revealed that body mass index (BMI) was associated with specific postexercise hemodynamic responses. Higher BMI was associated with greater reductions in CO and stroke volume, but lower reductions in total peripheral resistance. These findings suggest body composition impacts on mechanisms of PEH and should therefore be considered as an important confounding variable in future studies.

Adult↗

PubMed2003

The effect of acute plasma volume expansion on venous capacitance.

AIM: The purpose of this study was to examine the effect of plasma volume (PV) expansion, induced by 1 single bout of high intensity exercise, on venous capacitance. METHODS: Fourteen active but untrained healthy young males were randomly assigned to an exercise (n=7) or control group (n=7). The exercise protocol consisted of 8 4-min bouts of exercise at 70-85% of maximal oxygen consumption (VO(2)max) with 5-min recovery periods between bouts. Resting and exercise HR and venous capacitance were assessed before and 24 hours after one bout of cycle exercise. Exercise HR was assessed during cycle exercise at 30, 45, and 60% of VO(2)max, whereas forearm and leg venous capacitance were examined by determining limb volume change after 2 min of venous occlusion at 50 mmHg. PV, plasma albumin, and sodium and potassium concentration were analysed pre and 24 hours post exercise. RESULTS: Twenty-four hours after one single bout of exercise, PV was increased by 7.7%. The increase in PV was accompanied by a decrease in exercise HR of 5.8% at the 2 higher intensities (45 and 60% of VO(2)max) but no change in venous capacitance was found. No significant changes in plasma albumin and sodium concentration occurred, although potassium concentration was significantly increased by 29%. CONCLUSION: An acute exercise-induced increase in plasma volume appears to be able to reduce exercise HR but has no effect on venous capacitance.

Adolescent↗

PubMed2003

Plasma lipid and fibrinogen levels in aerobically trained and untrained postmenopausal women.

AIM: Physically active compared to inactive pre-menopausal women typically possess higher high-density lipoprotein (HDL) cholesterol and reduced plasma fibrinogen levels. The aim of this study was to compare resting blood lipid and fibrinogen levels of aerobically trained and untrained postmenopausal females. METHODS: Subjects were 13 aerobically trained (trained) and 26 untrained postmenopausal females (untrained) all on hormonal replacement therapy. Mean age of trained was 56 years (SD=3.6) and untrained was 58 years (SD=4.1). Testing involved blood sampling after an overnight fast. Plasma blood lipids were assessed through enzymatic methods, whereas plasma fibrinogen was measured through the Clauss method. RESULTS: Trained compared to untrained had significantly greater free fatty acid (51%, p<0.05) and apolipoprotein A levels (24%, p<0.05) and significantly lower fibrinogen (20%, p<0.05). Trained compared to untrained also possessed significantly lower total cholesterol/HDL cholesterol ratio (20%, p<0.05), total cholesterol/apolipoprotein A ratio (19%, p<0.05), apolipoprotein B/apolipoprotein A ratio (35%, p<0.05), and significantly higher HDL cholesterol (22%, p<0.05) although these differences were not significant after adjusting for body mass index (BMI). CONCLUSION: These results show that both a physically active lifestyle and a low BMI contribute to the improved lipid and fibrinogen levels of exercising postmenopausal women.

Fatty Acids, Nonesterified↗

PubMed2002

Cardiovascular and renal responses to mental challenge in highly and moderately active males with a family history of hypertension.

The objective of this study was to compare FBF and renal responses to mental challenge in highly and moderately active males with a family history of hypertension. Normotensive, healthy males with a family history of hypertension (n = 18) were recruited into moderately active and highly active groups. Cardiovascular, FBF, and renal responses to a 10-min Stroop mental challenge were measured. Urine was analysed for levels of sodium and potassium pre and post stressor as an indicant of renal blood flow. The results were that the moderately active males demonstrated a significantly higher level of FBF reactivity to mental challenge compared with that of the highly active. Heart rate change and FBF change during the stressor were positively correlated (r = 0.75, P < 0.01). Both groups, however, demonstrated a similar pattern of sodium excretion to mental challenge. These findings suggest that physical activity level is associated with FBF reactivity but not renal reactivity to mental challenge in offspring hypertensives. That sodium excretion was no different post-stressor in the moderately active group suggests that the exaggerated forearm vasodilatation response was not due to renal vasoconstriction.

Adult↗

PubMed2001

Cardiovascular response of trained and untrained old men to mental challenge.

PURPOSE: The cardiovascular response to mental challenge of trained and untrained older men was examined. METHODS: Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance (TPR), rate pressure product, and cardiac contractility of 10 aerobically trained (trained) and 10 untrained (untrained) older men during and recovering from the Stroop task were compared. Fitness was assessed by online, open-circuit spirometry using a bicycle ergometer. RESULTS: Trained compared with untrained men showed significantly lower absolute heart rate during and recovering from the Stroop and greater left ventricular ejection time recovering from Stroop. Delta TPR scores were greater for Trained during and recovering from the Stroop, whereas delta systolic blood pressure was greater recovering from Stroop. CONCLUSION: These results indicate that although aerobically trained men possessed lower absolute heart rate their change in TPR and systolic blood pressure during mental challenge was significantly greater than that of untrained older men. The greater vascular response of the trained to mental challenge may reflect greater sensitivity to alpha-adrenergic stimulation.

Aged↗

PubMed1999

Cardiovascular responses to light isometric and aerobic exercise in 21- and 59-year-old males.

The effects of aging on the cardiovascular response to continuous light isometric and aerobic exercise remains to be determined. Thus, the purpose of this study was to compare the cardiovascular response of young and older males during light handgrip and cycle ergometry exercise. Blood pressure, heart rate, rate pressure product, as well as pre-ejection period (derived from impedance cardiography) were obtained for 15 young [mean (SE) age: 21 (0.7) years] and 15 older males [59 (0.8) years] during and after light handgrip exercise and cycle ergometry. The parasympathetic influence on the heart was also assessed through a time-series analysis of heart period variability (HPVts). Both during and when recovering from the handgrip exercise and cycle ergometry, the older subjects exhibited a significantly higher absolute systolic and diastolic blood pressure, and rate pressure product, and a lower HRVts than the young subjects. Relative to baseline, the change in pre-ejection period was lower for the young subjects during the handgrip and cycle ergometry, tasks. These results indicate that although the sympathetic influence on both the myocardium and the vasculature was less pronounced in the older males, the aging cardiovasculature was under greater hemodynamic stress both during rest and during exposure to light isometric and aerobic challenge.

Adult↗

PubMed1998

Cardiovascular response to passive cycle exercise.

PURPOSE: Cardiovascular response of trained males (N = 20) and fit but untrained controls (N = 10) were examined during rest and passive cycle exercise (PCE). METHODS: Heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR), and mean arterial pressure (MAP) were measured during PCE for 6 min at intensities of 30 and 60 rpm. Also vagal influence on the heart was assessed through time series analysis of heart period variability (HPVts) at high and medium frequencies. Electromyography (EMG) was used to monitor muscle activity during PCE. RESULTS: During PCE no differences in cardiovascular response were found between the trained and untrained groups; thus groups were combined for the remainder of the analysis. Results indicated that during light and medium PCE all subjects combined showed a significant increase in HR, CO, and MAP and a significant decrease in HPVts (P < 0.001). CONCLUSION: The increase in HR during passive exercise may be a result of the stimulation of mechanoreceptors. The small and similar SV response during PCE of both groups suggests that the muscle pumps may not be effective during this form of passive exercise.

Adolescent↗

PubMed1998

Heart period variability of trained and untrained men at rest and during mental challenge.

The effect of aerobic training on parasympathetic reactivity to mental stress is unclear. Thus, the parasympathetic response, as assessed by time series analysis of heart period variability (HPVts), of 10 trained male runners (trained group), 10 inherently low resting heart rate untrained men (low HR group), and 10 normal resting HR men (control group) at rest and to two mental stressors was examined. Participants completed a mental arithmetic and Stroop task. Resting HPVts at high and medium frequencies was significantly greater for the trained and the low HR groups than for the control group. Significantly greater decreases in HPVts at the medium frequency during arithmetic recovery were measured for the trained and low HR groups compared with the response of the control group. Significantly greater decreases in HPVts at both the the high and medium frequencies during the first two epochs of the Stroop occurred only for the trained and low HR groups. These results suggest that the greater HPVts at rest and decline in HPVts during and after mental challenge is influenced by both aerobic training and genetic inheritance.

Adult↗

PubMed1997

Stroke volume response to cycle ergometry in trained and untrained older men.

UNLABELLED: The aims of this study were threefold: (1) to investigate the stroke volume (SV) response of trained older male cyclists [Cyclists: 65 (2.1) years, n = 10] during incremental cycle ergometry (20 W.min-1); (2) to determine the SV dynamics and total peripheral resistance response of untrained, but healthy and active older male controls [ CONTROLS: 66 (1.1) years; n = 10]; (3) to compare the maximum oxygen consumption (VO2max) and SV response of trained older male runners [Runners: 65 (3.4) years; n = 11] with that of age-matched Cyclists. Impedance cardiography was used to assess the response of cardiac output (CO), SV and total peripheral resistance to exercise involving cycle ergometry. The mean VO2max of the trained Cyclists [54 (1.6) ml.kg-1.min-1] was significantly higher (P < 0.05) than that of the Runner [48 (3.9) ml.kg-1.min-1], whereas both groups possessed a significantly higher VO2max than the CONTROLS [28 (1.3) ml.kg-1.min-1]. During exercise, at a heart rate of 90 beats.min-1, the SV of the Cyclists increased by 41%, that of the Runners increased by 47%, and that of the CONTROLS increased by 31%. However, the Cyclists' and Runners' SV response was significantly greater than that of the CONTROLS. The SV for cyclists and controls peaked at 30% of VO2max. This early increase in SV was a major factor underlying the increase in CO during exercise in both the trained and the untrained subjects. In addition, all three groups showed a significant decrease in total peripheral resistance throughout exercise. The finding that older male runners possessed a large exercise SV and high VO2max suggests that run training results in enhanced cardiovascular performance during cycle ergometry.

Aged↗

PubMed1996

Cardiovascular response of young and older males to mental challenge.

Blood pressure, heart rate, rate pressure product, heart rate variability, stroke volume, cardiac output, peripheral resistance, and cardiac contractility derived from impedance cardiography were obtained from 15 young and 15 old males during and after the Stroop task. The old group demonstrated significantly higher absolute heart rate, systolic and mean arterial pressure, peripheral resistance, and rate pressure product, and lower cardiac output, stroke volume, and heart rate variability both during and recovering from Stroop. The young group showed significantly greater relative heart rate increase at the start of Stroop, higher relative levels of contractility during and recovering, and greater relative levels of peripheral resistance during and recovering from Stroop. Overall, old compared to young subjects possessed greater absolute but smaller relative cardiovascular responses during and recovering from Stroop. These results suggest that although the aging cardiovasculature may be less reactive, it may be under greater hemodynamic stress both during rest and mental challenge.

Adult↗

PubMed1995

Association between heart rate variability and training response in sedentary middle-aged men.

The effect of exercise training on heart rate variability (HRV) and improvements in peak oxygen consumption (VO2peak) was examined in sedentary middle-aged men. The HRV and absolute and relative VO2peak of training (n = 19) and control (n = 15) subjects were assessed before and after a 24-session moderate intensity exercise training programme. Results indicated that with exercise training there was a significantly increased absolute and relative VO2peak (P < 0.005) for the training group (12% and 11% respectively) with no increase for the control group. The training group also displayed a significant reduction in resting heart rate; however, HRV remained unchanged. The trained subjects were further categorized into high (n = 5) and low (n = 5) HRV groups and changes in VO2peak were compared. Improvements in both absolute and relative VO2peak were significantly greater (P > 0.005) in the high HRV group (17% and 20% respectively) compared to the low HRV group (6% and 1% respectively). The groups did not differ in mean age, pretraining oxygen consumption, or resting heart rate. These results would seem to suggest that a short aerobic training programme does not alter HRV in middle-aged men. Individual differences in HRV, however, may be associated with VO2peak response to aerobic training.

Adult↗

PubMed1995

Heart rate response to psychological stressors of individuals possessing resting bradycardia.

The authors examined the relation between trained and inherent bradycardia and heart rate (HR) and T-wave amplitude response to psychological stressors. They compared cardiac responses to two psychological stressors of 10 trained male runners (MVo2max = 75 mL/kg-1 min-1) possessing low resting heart rate (M = 58 bpm), 10 untrained men (MVo2max = 58 mL/kg-1 min-1) with inherently low resting heart rate (M = 58 bpm), and 10 unconditioned men (MVo2max = 51 mL/kg-1 min-1) with normal resting heart rate (M = 69 bpm). All participants completed a maximal oxygen consumption treadmill test, an easy and a hard mental arithmetic task, and the Stroop Color and Word Test. Their analysis of the data revealed no significant differences in relative heart rate response or T-wave amplitude between groups during or after any stressor. In contrast, absolute heart rates during and after mental arithmetic and during the Stroop test were significantly lower for both the trained and inherently low groups compared with the control group. These findings suggest that the lower absolute HR response during and after stressors was influenced by both aerobic training and genetic inheritance.

Adult↗

PubMed1995

Forehead skin temperature and thermal sensation during exercise in cool and thermoneutral environments.

BACKGROUND: The influence of forehead and mean skin temperature on thermal sensation during exercise in hot, cool, and thermoneutral environments is unclear. HYPOTHESIS: We hypothesized that forehead temperature, in contrast to other skin sites, would contribute significantly to thermal sensation during exercise in hot, cool, and thermoneutral environments. METHOD: Volunteer males (N = 14) performed 30 min of constant load exercise on a cycle ergometer during which thermal sensation, skin and rectal temperatures, and heart rate were collected. Each subject participated in a control (24 degrees C), hot (40 degrees C), and cool (8 degrees C) condition. RESULTS: Significantly higher mean skin temperatures occurred during exercise in the hot condition (M = 37.22 +/- 0.20 degrees C) compared to exercise in the neutral (M = 33.34 +/- 0.51 degrees C) and cool conditions (M = 27.92 +/- 0.22 degrees C). Forehead skin temperature in the neutral and cool conditions was significantly greater than forearm, hand, thigh, and calf skin temperatures (p < 0.05). In the hot condition, forehead temperature was significantly greater than back, chest, upper arm, and hand skin temperatures (p < 0.05). In contrast to the neutral and hot conditions, forehead skin temperature was significantly associated with thermal sensation during exercise in the cool condition (r consistently > 0.67). CONCLUSIONS: We conclude that forehead skin temperature, in contrast to other skin sites, contributed significantly to thermal sensation during exercise in the cool.

Adult↗

PubMed1993

Ratings of perceived exertion and affect in hot and cool environments.

The effects of hot and cool environments on perceptual and physiological responses during steady-state exercise were examined in men (n = 14) performing 30 min of constant exercise (cycle ergometry) at a perceived exertion of "somewhat hard". Subjects exercised at the same absolute exercise intensity in hot (40 degrees C), neutral (24 degrees C), and cool (8 degrees C) conditions. Data were collected for differential ratings of perceived exertion (RPE), affect, thermal sensation, mean skin (Tsk) and rectal temperatures (Tre), and cardiac frequency (fc). The subjects completed the hot exposure with an average Tsk of 37.5 degrees C (SEM 0.11), while the neutral and cool conditions produced values of 33.8 (SEM 0.09) and 28.2 degrees C (SEM 0.30), respectively. The Tsk was significantly higher in the hot than the neutral and cool conditions throughout exercise (P < 0.05). The fc was significantly lower in the cool than in the other conditions (P < 0.05), and the subjects completed the hot exposure with a mean fc more than 20 beats.min-1 greater than observed in the other conditions. The subjects felt worse (lower affect) in the heat throughout exercise (P < 0.05). Overall RPE was significantly lower in the cool than in the heat, while chest RPE scores for the cool and hot conditions were displaced vertically by approximately two points. Subjects perceived work to be harder, felt worse, and experienced greater thermal sensation in the hot condition, compared with the neutral and cool conditions. Changes in cutaneous vasomotor tone and heat-induced influences on the chest may have accounted for the RPE changes observed in the heat.

Adult↗

PubMed1993

Cardiac response of trained and untrained males to a repeated psychological stressor.

The authors examined cardiac response to repeated exposure to a psychological stressor of aerobically conditioned (n = 15) and unconditioned subjects (n = 15). Heart rate and electrocardiographic T-wave amplitude responses of 10 trials of the Stroop Test were monitored during and after performance. Both groups' adaptation patterns were similar, with a plateauing of heart rate response after the third trial. Compared with the unconditioned group, however, the aerobically conditioned subjects recorded lower absolute heart rate responses during and after the stressor for every trial. Relative heart rate responses during the stressor and recovery were similar for both groups. There was also no difference between groups in T-wave response during or after the stressor. These data suggest that absolute heart rate response during and after repeated exposure to a psychological stressor is lower for aerobically trained individuals.

Adult↗

PubMed1993

Heart-rate and blood-pressure responses to speech alone compared with cognitive challenges in the Stroop task.

Heart-rate and blood-pressure responses are assumed to reflect the "stressfulness" of cognitive tasks. Cardiovascular responses to speech are often assumed to be negligible. To test these assumptions, 34 middle-aged men (mean age 45.0 +/- 6.1) performed three versions of the Stroop color-conflict task, passive responding, push-button, and verbal. Although difficulty of passive responding was rated 11.8 (fairly light), push-button 16.1 (between hard and very hard), and verbal Stroop 14.5 (hard), all were significantly different. Analysis of variance showed during tasks heart-rate responses and systolic blood pressure did not differ. Recovery average heart-rate and over-all heart-rate patterns were not different for the difficult tasks but were significantly different from the easy task. Diastolic blood-pressure changes during tasks were more similar for verbal tasks despite the difference in difficulty. Stressor heart-rate and systolic blood-pressure responses did not reflect the difficulty of this stressful task. Verbalization of responses contributed significantly to cardiovascular reactivity.

Adult↗

PubMed1992

The effect of participation in an exercise training program on cardiovascular reactivity in sedentary middle-aged males.

Exaggerated cardiovascular reactivity to mental stressors may be a risk factor for cardiovascular disease. To determine if participation in a moderate intensity aerobic exercise training program reduces cardiovascular reactivity to laboratory stressors, 40 sedentary middle-aged males were randomly assigned: training group (n = 25) and control group (n = 15). Cardiovascular reactivity during and after three mental stressors (passive responding, push-button Stroop and verbal Stroop) and mild exercise (bicycle ergometer) was assessed before and after an 8-week intervention. VO2(peak) was determined using the Balke protocol. Among 19 subjects who completed the training, VO2(peak) increased 13.7%. Also, trained compared to untrained subjects showed significant reductions in baseline and absolute heart rate responses to all stressors. Baseline adjusted heart rates were significantly lower during push-button Stroop recovery and during verbal Stroop. Blood pressure, T-wave amplitude, finger pulse amplitude and pulse transit time responses were unaffected by exercise training. It was concluded that participation in a short-term, moderate intensity aerobic exercise training program may have a cardioprotective effect by significantly reducing absolute and baseline-adjusted heart rate responses to stressors.

Adult↗

PubMed1992

The effects of smokeless tobacco on performance and psychophysiological response.

The effects of smokeless tobacco (ST) on psychophysiological response and performance were examined in two studies. Study 1 compared heavy and moderate ST users on psychomotor tasks (simple reaction time/anticipation time and choice reaction time/movement time) in ST (2 g amount) and no smokeless tobacco (NST) conditions. Moderate users performed significantly better than heavy users; there were no significant psychomotor performance differences comparing ST/NST conditions. Heart rate and blood pressure were elevated equally for both groups with the use of ST. Heavy users reported significantly less state anxiety in both ST and NST conditions than moderate users. Study 2 replicated the psychomotor performance results of study 1 when comparing nonusers and ST users who were given four dose amounts of ST (NST, 1/3 mean dose, mean dose, and 5/3 mean) over 4 d. For the math and Stroop tasks, ST use resulted in 12.1% and 10.4% better performance than the NST condition. Physiological measures showed significant elevations during the ST conditions. No differences between dose amounts of ST were apparent for any of the measures. These studies demonstrate that ST users perform better than nonusers when having to react to cognitively challenging task situations.

Adult↗