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Kenneth R. Turley and Jack H. Wilmore

This study investigated whether cardiovascular responses at a given submaximal oxygen consumption (V̇O2, L · min-1) are different between the treadmill (TM) and cycle ergometer (CE). Submaximal cardiovascular measurements were obtained at three work rates on both the TM and CE in 7- to 9-year-old children (12 males and 12 females). Using regression analysis, it was determined that there were no differences between the TM and CE in cardiac output (L · min-1), stroke volume (SV, ml · beat-1) or heart rate (beats · min-1) at a given V̇O2 (L · min-1). There were differences in the total peripheral resistance (TPR, units) and arterial-venous oxygen difference (a-vO2 diff, ml · 100 ml-1) to V̇O2 (L · min-1) relationship. While there were statistically significant differences in TPR and a-vO2 diff between the two modalities, there was substantial overlap of individual values at any given submaximal V̇O2, thus the physiological significance is questionable. Hence, we conclude that in 7- to 9-yearold children there are no differences in submaximal cardiovascular responses between the CE and TM.

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Mandy L. Gault, Richard E. Clements and Mark E.T. Willems

Cardiovascular responses of older adults to downhill (DTW, –10% incline) and level treadmill walking (0%) at self-selected walking speed (SSWS) were examined. Fifteen participants (age 68 ± 4 yr, height 1.69 ± 0.08 m, body mass 74.7 ± 8.1 kg) completed two 15-min walks at their SSWS (4.6 ± 0.6 km/hr). Cardiovascular responses were estimated using an arterial-volume finger clamp and infrared plethysmography. Oxygen consumption was 25% lower during DTW and associated with lower values for stroke volume (9.9 ml/beat), cardiac output (1.0 L/min), arteriovenous oxygen difference (a-v O2 diff, 2.4 ml/L), and systolic blood pressure (10 mmHg), with no differences in heart rate or diastolic and mean arterial blood pressure. Total peripheral resistance (TPR) was higher (2.11 mmHg) during DTW. During downhill walking, an exercise performed with reduced cardiac strain, endothelial changes, and reduced metabolic demand may be responsible for the different responses in TPR and a-v O2 diff. Future work is warranted on whether downhill walking is suitable for higher risk populations.

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Elizabeth Thompson, Theo H. Versteegh, Tom J. Overend, Trevor B. Birmingham and Anthony A. Vandervoort

Our purpose was to describe heart rate (HR), mean arterial blood pressure (MAP), and perceived exertion (RPE) responses to submaximal isokinetic concentric (CON) and eccentric (ECC) exercise at the same absolute torque output in older adults. Peak torques for ECC and CON knee extension were determined in healthy older males (n = 13) and females (n = 7). Subjects then performed separate, randomly ordered, 2-min bouts of CON and ECC exercise. Heart rate and MAP increased (p < .001) from resting values throughout both exercise bouts. CON exercise elicited a significantly greater cardiovascular response than ECC exercise after 60 s. Peak HR, MAP, and RPE after CON exercise were greater than after ECC exercise (p < .01). At the same absolute torque output, isokinetic CON knee extension exercise resulted in a significantly greater level of cardiovascular stress than ECC exercise. These results are relevant to resistance testing and exercise in older people.

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Karla A. Kubitz and Daniel M. Landers

This study examined the effects of an 8-week aerobic training program on cardiovascular responses to mental stress. Dependent variables included electrocardiographic activity, blood pressure, electroencephalographic (EEG) activity, state anxiety, and state anger. Quantification of indicators of sympathetic, parasympathetic, and central nervous system activity (i.e., respiratory sinus arrhythmia, T-wave amplitude, and EEG activity, respectively) allowed examination of possible underlying mechanisms. Subjects (n = 24) were randomly assigned to experimental (training) and control (no training) conditions. Pre- and posttesting examined cardiorespiratory fitness and responses to mental stress (i.e., Stroop and mental arithmetic tasks). MANOVAs identified a significant effect on cardiorespiratory fitness, heart rate, respiratory sinus arrhythmia, and EEG alpha laterality. The results appear consistent with the hypothesis that enhanced parasympathetic nervous system activity and decreased central nervous system laterality serve as mechanisms underlying certain aerobic training effects.

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Christine L. LaLanne, Michael S. Cannady, Joseph F. Moon, Danica L. Taylor, Jeff A. Nessler, George H. Crocker and Sean C. Newcomer

Participation in surfing has evolved to include all age groups. Therefore, the purpose of this study was to determine whether activity levels and cardiovascular responses to surfing change with age. Surfing time and heart rate (HR) were measured for the total surfing session and within each activity of surfing (paddling, sitting, wave riding, and miscellaneous). Peak oxygen consumption (VO2peak) was also measured during laboratory-based simulated surfboard paddling on a modified swim bench ergometer. VO2peak decreased with age during simulated paddling (r = –.455, p < .001, n = 68). Total time surfing (p = .837) and time spent within each activity of surfing did not differ with age (n = 160). Mean HR during surfing significantly decreased with age (r = –.231, p = .004). However, surfing HR expressed as a percent of age-predicted maximum increased significantly with age. Therefore, recreational surfers across the age spectrum are achieving intensities and durations that are consistent with guidelines for cardiovascular health.

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L.P. Kilduff, E. Georgiades, N. James, R.H. Minnion, M. Mitchell, D. Kingsmore, M. Hadjicharalambous and Y.P. Pitsiladis

The effects of creatine (Cr) supplementation on cardiovascular, metabolic, and thermoregulatory responses, and on the capacity of trained humans to perform prolonged exercise in the heat was examined. Endurance-trained males (n = 21) performed 2 constant-load exercise tests to exhaustion at 63 ± 5 % VO2max in the heat (ambient temperature: 30.3 ± 0.5 °C) before and after 7 d of Cr (20 g · d–1 ’ Cr + 140 g • d–1 glucose polymer) or placebo. Cr increased intraccl-lular water and reduced thermoregulatory and cardiovascular responses (e.g., heart rate, rectal temperature, sweat rate) but did not significantly increase time to exhaustion (47.0 ± 4.7 min vs. 49.7 ± 7.5 min, P = 0.095). Time to exhaustion was increased significantly in subjects whose estimated intramuscular Cr levels were substantially increased (“responders”: 47.3 ± 4.9 min vs. 51.7 ± 7.4 min, P = 0.031). Cr-induced hyperhydration can result in a more efficient thermoregulatory response during prolonged exercise in the heat.

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Gi Broman, Miguel Quintana, Margareta Engardt, Lennart Gullstrand, Eva Jansson and Lennart Kaijser

The aim of the study was to examine submaximal and maximal physiological responses and perceived exertion during deep-water running with a vest compared with the responses during treadmill running in healthy elderly women. Eleven healthy women 70 ± 2 years old participated. On two different occasions they performed a graded maximal exercise test on a treadmill on land and a graded maximal exercise test in water wearing a vest. At maximal work the oxygen uptake was 29% lower (p < .05), the heart rate was 8% lower (p < .05), and the ventilation was 16% lower (p < .05) during deep-water running than during treadmill running. During submaximal absolute work the heart rate was higher during deep-water running than during treadmill running for the elderly women. The participants had lower maximal oxygen uptake, heart rate, ventilation, respiratory-exchange ratio, and rate of perceived exertion during maximal deep-water running with a vest than during maximal treadmill running. These responses were, however, higher during submaximal deep-water running than during treadmill running.

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Juliane P. Hernandez, Kristin Roever and Tonya Seed

This investigation attempted to determine whether heart-rate and blood pressure responses to maximal acute lower body negative pressure (LBNP) are exacerbated compared with maximal graded LBNP in active older (n = 9, 70 ± 7 yr) and endurance-trained younger (n = 10, 23 ± 3 yr) individuals. Heart rate increased earlier during graded LBNP in the younger group (−40 mm Hg vs. tolerance) and was significantly higher than that of the older adults at the point of tolerance. Mean arterial pressure (MAP) decreased more in the older than the younger individuals during graded LBNP. LBNP-tolerance index was significantly greater in the younger group (309 ± 52 vs. 255.6 ± 48 mm Hg/min). Acute doses of LBNP elicited slower heart-rate responses in the older group. Despite these age-related differences, MAP responses were not different between groups with acute LBNP, so age per se does not appear to predispose individuals to orthostatic intolerance.

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Richard Mulholland Jr. and Alexander W. McNeill

The purpose of the study was to evaluate the effects of physical activities on the cardiovascular performances of three institutionalized, profoundly retarded, multiply handicapped children. Heart rates were recorded during the completion of selected motor activities using a combination of telemetered electrocardiograms (ECG) and standard wireless microphone/video technology. Each subject participated in the experiment for a minimum of 6 weeks. The relationships between mean heart rates and performance times for each subject were evaluated throughout the experiment. Based upon the data collected, it was concluded that gross motor activities may have a significant effect on the cardiorespiratory functioning of profoundly retarded, multiply handicapped children, provided the activities are performed for an extended period of time and on a regular basis. The activities selected for use in this study were developmentally based, and no special consideration was given to their aerobic demands on the subjects. The subjects’ level of functioning dictated the use of developmental criteria rather than other, more fitness oriented, criteria that are usually applied to nonhandicapped individuals.

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Lee J. Moore, Samuel J. Vine, Mark R. Wilson and Paul Freeman

Competitive situations often hinge on one pressurized moment. In these situations, individuals’ psychophysiological states determine performance, with a challenge state associated with better performance than a threat state. But what can be done if an individual experiences a threat state? This study examined one potential solution: arousal reappraisal. Fifty participants received either arousal reappraisal or control instructions before performing a pressurized, single-trial, motor task. Although both groups initially displayed cardiovascular responses consistent with a threat state, the reappraisal group displayed a cardiovascular response more reflective of a challenge state (relatively higher cardiac output and/or lower total peripheral resistance) after the reappraisal manipulation. Furthermore, despite performing similarly at baseline, the reappraisal group outperformed the control group during the pressurized task. The results demonstrate that encouraging individuals to interpret heightened physiological arousal as a tool that can help maximize performance can result in more adaptive cardiovascular responses and motor performance under pressure.