Effects of Posture, Load, and Rate of Carry on Task Heart Rates

1984 ◽  
Vol 28 (11) ◽  
pp. 1000-1002
Author(s):  
Stephen J. Morrissey
Keyword(s):  
Heart Rate ◽  
Task Performance ◽  
Level Surface ◽  
Experimental Conditions ◽  
Value Analysis ◽  
Heart Rates ◽  
Actual Load ◽  
Male Subjects

Five well trained male subjects carried loads on a level surface with five levels of task weight, five levels of distance carried, five levels of rate of carriage, and in five task postures set between normal erect and stoopwalking under ceilings set at 80 percent of each subject's normal erect stature. The tasks were performed for 15 minutes, and heart rate measured during the last 5 minutes of task performance and averaged for the condition-subject value. Analysis of the resulting task heart rates found there to be little change due to the experimental conditions tested. Only in the most stooped postures and with the heaviest loads, did large (but not significant) differences in task heart rate appear. It was concluded that for the range of conditions examined, well trained male subjects were able to recover adequately in the period between the actual load carries.

Cardiorespiratory responses during prolonged exercise

1961 ◽  
Vol 16 (6) ◽  
pp. 997-1000 ◽  
Author(s):  
Ernest D. Michael ◽  
Kenneth E. Hutton ◽  
Steven M. Horvath
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Energy Cost ◽  
Prolonged Exercise ◽  
Bicycle Ergometer ◽  
Maximum Oxygen Uptake ◽  
Healthy Male ◽  
Heart Rates ◽  
Cardiorespiratory Responses ◽  
Male Subjects

Three healthy male subjects 20 years of age were exercised for 2—8 hr riding a bicycle ergometer or walking on a treadmill. Higher heart rates were found with the bicycle rides than with the walking exercises with equivalent oxygen uptakes. The subjects could not work on the bicycle ergometer at oxygen uptakes of 1.8 liters/min for more than 4 hr but could with this uptake walk 8 hr. The results indicated that an 8-hr period of exercise could be completed without undue fatigue whenever the energy cost did not exceed 35% of the maximum oxygen uptake where heart rates, oxygen uptakes, and rectal temperatures remained below 120 beats/min, 1.4 liters/min, and 38 C, respectively. The heart rate appeared to be the important factor for estimating 8-hr work endurance. A rate of 140 beats/min could not be maintained for more than 4 hr or a rate of 160 beats/min for more than 2 hr without extreme fatigue. Submitted on October 26, 1960

Oxygen deficit and stores at onset of muscular exercise in humans

1983 ◽  
Vol 55 (1) ◽  
pp. 146-153 ◽  
Author(s):  
P. E. Di Prampero ◽  
U. Boutellier ◽  
P. Pietsch
Keyword(s):  
Heart Rate ◽  
Blood Lactate ◽  
Recovery Period ◽  
Oxygen Deficit ◽  
Experimental Conditions ◽  
Air Breathing ◽  
Single Breath ◽  
Male Subjects ◽  
Exercise In Humans ◽  
O2 Deficit

Single-breath O2 consumption (VO2) at the mouth and heart rate were determined in five healthy male subjects at rest, during 8 min of cycloergometric exercise (50, 100, 125, and 150 W), and in the recovery period following two experimental conditions: air breathing throughout (AA); hypoxic breathing (FIO2 = 0.11) for 6 min of preexercise rest followed by air breathing from the onset of exercise (HA). The O2 deficits and debts as well as the t 1/2 values of the VO2 on- and off-responses were determined and blood lactate concentrations measured at rest and in the recovery after 4 and 8 min of exercise. At all work loads: 1) O2 deficits were on the average 0.39 liter smaller in HA than in AA; 2) VO2 on-responses were faster in HA (t 1/2 approximately equal to 7 s) than in AA (t 1/2 = 20-30 s); and 3) O2 debts and VO2 off-responses were the same in the two conditions. Since the VO2 and heart rate levels at steady state as well as the blood lactate concentrations after 4 and 8 min of exercise were the same in AA and HA, the observed differences of O2 deficit cannot be attributed to changes of energy metabolism in the two conditions; they therefore depend on the reduction of body O2 stores at rest in HA. This, independently measured, was found to be 0.46 liters, not far from the observed O2 deficit difference (0.39 liters). Thus a decrease of O2 stores before exercise is accompanied by a reduction of the O2 deficit and faster VO2 kinetics at the onset of exercise.

The effectiveness of adaptive training for stress inoculation in a simulated astronaut task

2021 ◽  
Vol 65 (1) ◽  
pp. 1541-1545
Author(s):  
Tor Finseth ◽  
Michael C. Dorneich ◽  
Nir Keren ◽  
Warren Franke ◽  
Stephen Vardeman ◽  
...  
Keyword(s):  
Heart Rate ◽  
Task Performance ◽  
Stress Responses ◽  
Training System ◽  
Stress Inoculation ◽  
Stress System ◽  
Smoke Alarms ◽  
Experimental Conditions ◽  
Adaptive Training ◽  
Adaptive Condition

Astronauts operate in an environment with multiple hazards that can develop into life-threatening emergency situations. Managing stress in emergencies may require cognitive resources and lead to diminishing performance. Stress training aims to maintain performance under stress by methodically increasing stressor levels to build inoculation against stress. An adaptive virtual reality (VR) training system was developed with real-time stress detection by using machine learning on psychophysiological responses. Using a VR simulation of a spaceflight emergency fire, stress classifications were used to trigger adaptations of the VR environmental stressors (e.g., smoke, alarms, flashing lights), with the goal of maintaining a manageable level of stress during training. Fifty-seven healthy subjects underwent task training over eight trials with adaptive training (adaptive, n=19); results were compared to trials with predetermined gradual increases in stressors (graduated, n=18), and with trials with constant low-level stressors (skill-only, n=20). Stress responses were measured through heart rate, heart rate variability (i.e., root mean squared of successive differences (RMSSD), low frequency to high frequency (LF/HF) ratio), and task performance (distance-from-fire). Heart rate decreased and RMSSD increased pre-post training for all experimental conditions. The LF/HF ratio decreased pre-post training for the adaptive condition, but not in the other conditions. Results suggests that all conditions had lower stress, but the adaptive condition was more successful. Task performance showed a marginal increase across trials for the adaptive condition. Preliminary results suggest that training with the adaptive stress system can prepare individuals for responding to stressors better than skill-only and graduated training.

Heart Rate Variability, Homeostasis, and Brain Function

2012 ◽  
Vol 26 (4) ◽  
pp. 178-203 ◽  
Author(s):  
Francesco Riganello ◽  
Sergio Garbarino ◽  
Walter G. Sannita
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Vegetative State ◽  
Communication Disorders ◽  
Affective States ◽  
Experimental Conditions ◽  
Cardiovascular Research ◽  
Sensory Stimuli ◽  
Additional Information ◽  
Brain Injured

Measures of heart rate variability (HRV) are major indices of the sympathovagal balance in cardiovascular research. These measures are thought to reflect complex patterns of brain activation as well and HRV is now emerging as a descriptor thought to provide information on the nervous system organization of homeostatic responses in accordance with the situational requirements. Current models of integration equate HRV to the affective states as parallel outputs of the central autonomic network, with HRV reflecting its organization of affective, physiological, “cognitive,” and behavioral elements into a homeostatic response. Clinical application is in the study of patients with psychiatric disorders, traumatic brain injury, impaired emotion-specific processing, personality, and communication disorders. HRV responses to highly emotional sensory inputs have been identified in subjects in vegetative state and in healthy or brain injured subjects processing complex sensory stimuli. In this respect, HRV measurements can provide additional information on the brain functional setup in the severely brain damaged and would provide researchers with a suitable approach in the absence of conscious behavior or whenever complex experimental conditions and data collection are impracticable, as it is the case, for example, in intensive care units.

Identifying Patterns in Complex Field Data

2017 ◽  
Vol 225 (3) ◽  
pp. 268-284 ◽  
Author(s):  
Andrew J. White ◽  
Dieter Kleinböhl ◽  
Thomas Lang ◽  
Alfons O. Hamm ◽  
Alexander L. Gerlach ◽  
...  
Keyword(s):  
Heart Rate ◽  
Panic Disorder ◽  
Latent Class ◽  
Treatment Protocol ◽  
Situational Factors ◽  
Self Report ◽  
Complex Field ◽  
Cluster Assignment ◽  
Experimental Conditions ◽  
Conventional Analysis

Abstract. Ambulatory assessment methods are well suited to examine how patients with panic disorder and agoraphobia (PD/A) undertake situational exposure. But under complex field conditions of a complex treatment protocol, the variability of data can be so high that conventional analytic approaches based on group averages inadequately describe individual variability. To understand how fear responses change throughout exposure, we aimed to demonstrate the incremental value of sorting HR responses (an index of fear) prior to applying averaging procedures. As part of their panic treatment, 85 patients with PD/A completed a total of 233 bus exposure exercises. Heart rate (HR), global positioning system (GPS) location, and self-report data were collected. Patients were randomized to one of two active treatment conditions (standard exposure or fear-augmented exposure) and completed multiple exposures in four consecutive exposure sessions. We used latent class cluster analysis (CA) to cluster heart rate (HR) responses collected at the start of bus exposure exercises (5 min long, centered on bus boarding). Intra-individual patterns of assignment across exposure repetitions were examined to explore the relative influence of individual and situational factors on HR responses. The association between response types and panic disorder symptoms was determined by examining how clusters were related to self-reported anxiety, concordance between HR and self-report measures, and bodily symptom tolerance. These analyses were contrasted with a conventional analysis based on averages across experimental conditions. HR responses were sorted according to form and level criteria and yielded nine clusters, seven of which were interpretable. Cluster assignment was not stable across sessions or treatment condition. Clusters characterized by a low absolute HR level that slowly decayed corresponded with low self-reported anxiety and greater self-rated tolerance of bodily symptoms. Inconsistent individual factors influenced HR responses less than situational factors. Applying clustering can help to extend the conventional analysis of highly variable data collected in the field. We discuss the merits of this approach and reasons for the non-stereotypical pattern of cluster assignment across exposures.

scholarly journals Eating behavior affects cardio-metabolic risk in high school teenagers in a developing country

2020 ◽  
Vol 29 (1) ◽  
pp. 71-81
Author(s):  
Rita Suhadi ◽  
Phebe Hendra ◽  
Dita Maria Virginia ◽  
Christianus Heru Setiawan
Keyword(s):  
Risk Factors ◽  
Heart Rate ◽  
Waist Circumference ◽  
Eating Behavior ◽  
Eating Behaviors ◽  
Metabolic Risk Factors ◽  
Metabolic Risk ◽  
Cross Sectional ◽  
Male Subjects ◽  
Female Subjects

BACKGROUND Modernization negatively changes lifestyle, characterized by excessive eating and reduced energy consumption, and concurrently increases the cardiometabolic risk. This study was aimed to evaluate the association between eating behavior and cardio-metabolic risk factors including body mass index (BMI) in percentile, blood pressure (BP) in percentile, waist circumference, and heart rate in total subjects and gender sub-groups. METHODS This analytical cross-sectional study was done from July to November 2018. High schools in four provinces of Indonesia and students were selected using purposive sampling. Subjects’ profiles were collected from interview and cardio-metabolic parameters were measured at the study sites. Data were analyzed with chi-square and independent t-test. RESULTS Subjects who were overweight/obese and had high BP accounted for 27.1% and 9.3–12.0% of the total subjects (n = 768), respectively. Subjects who having breakfast tended to have lower BMI (p = 0.006), and the lower consumption of western meals had lower heart rate (p = 0.02). Male subjects had more meal frequency and had less quantity of snacks than female subjects (p<0.001). Male subjects with routine intake of vegetables had low heart rate (p = 0.03). Female subjects with routine breakfast had better BMI (p<0.001), and lower diastolic BP (p = 0.004) and waist circumference (p = 0.02), whereas those who consumed Western meals had higher heart rate (p = 0.046) and waist circumference (p = 0.001). CONCLUSIONS Eating behaviors are likely to affect cardio-metabolic risk factors, and the effects vary within gender groups.

scholarly journals Heart Rate–Induced Myocardial Ca 2+ Retention and Left Ventricular Volume Loss in Patients With Heart Failure With Preserved Ejection Fraction

2020 ◽  
Vol 9 (17) ◽  
Author(s):  
Daniel N. Silverman ◽  
Mehdi Rambod ◽  
Daniel L. Lustgarten ◽  
Robert Lobel ◽  
Martin M. LeWinter ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Ejection Fraction ◽  
Sinus Rhythm ◽  
Left Ventricular ◽  
Atrial Pacing ◽  
Preserved Ejection Fraction ◽  
Volume Loss ◽  
Heart Rates ◽  
Patients With Heart Failure

Background Increases in heart rate are thought to result in incomplete left ventricular (LV) relaxation and elevated filling pressures in patients with heart failure with preserved ejection fraction (HFpEF). Experimental studies in isolated human myocardium have suggested that incomplete relaxation is a result of cellular Ca 2+ overload caused by increased myocardial Na + levels. We tested these heart rate paradigms in patients with HFpEF and referent controls without hypertension. Methods and Results In 22 fully sedated and instrumented patients (12 controls and 10 patients with HFpEF) in sinus rhythm with a preserved ejection fraction (≥50%) we assessed left‐sided filling pressures and volumes in sinus rhythm and with atrial pacing (95 beats per minute and 125 beats per minute) before atrial fibrillation ablation. Coronary sinus blood samples and flow measurements were also obtained. Seven women and 15 men were studied (aged 59±10 years, ejection fraction 61%±4%). Patients with HFpEF had a history of hypertension, dyspnea on exertion, concentric LV remodeling and a dilated left atrium, whereas controls did not. Pacing at 125 beats per minute lowered the mean LV end‐diastolic pressure in both groups (controls −4.3±4.1 mm Hg versus patients with HFpEF −8.5±6.0 mm Hg, P =0.08). Pacing also reduced LV end‐diastolic volumes. The volume loss was about twice as much in the HFpEF group (controls −15%±14% versus patients with HFpEF −32%±11%, P =0.009). Coronary venous [Ca 2+ ] increased after pacing at 125 beats per minute in patients with HFpEF but not in controls. [Na + ] did not change. Conclusions Higher resting heart rates are associated with lower filling pressures in patients with and without HFpEF. Incomplete relaxation and LV filling at high heart rates lead to a reduction in LV volumes that is more pronounced in patients with HFpEF and may be associated with myocardial Ca 2+ retention.

Heart Rate and Performance in Manual Missile Guidance

1971 ◽  
Vol 32 (2) ◽  
pp. 352-354
Author(s):  
Bengt Bergstroem ◽  
Peter Arnberg
Keyword(s):  
Heart Rate ◽  
Performance Data ◽  
Tracking Performance ◽  
Missile Guidance ◽  
Heart Rates ◽  
Laboratory Conditions ◽  
Stress Studies ◽  
And Performance

Earlier stress studies under laboratory conditions show that heart rates from 100 to 110 bpm are associated with significant decrements in missile-tracking performance. Data from real missile tracking by 8 operators with no stress deliberately induced indicate, however, that performance is unaffected up to 135 bpm, and only moderately affected in the 135- to 170-bpm region. The disagreement between the two sets of results highlights the difficulties in generalizing from stress experiments.

Stress level in wild harbour porpoises (Phocoena phocoena) during satellite tagging measured by respiration, heart rate and cortisol

2009 ◽  
Vol 89 (5) ◽  
pp. 885-892 ◽  
Author(s):  
I.G. Eskesen ◽  
J. Teilmann ◽  
B.M. Geertsen ◽  
G. Desportes ◽  
F. Riget ◽  
...  
Keyword(s):  
Heart Rate ◽  
Respiration Rate ◽  
Serum Cortisol ◽  
Phocoena Phocoena ◽  
Heart Rates ◽  
Stress Effects ◽  
Respiration Rates ◽  
Stressed Animal ◽  
Cortisol Levels ◽  
Satellite Tagging

During satellite tagging of harbour porpoises (Phocoena phocoena), heart rate, respiration rate and cortisol value were measured to evaluate stress effects during handling and tagging. Respiration rates were obtained using video recordings, heart rates were recorded and serum cortisol levels were analysed from blood samples. Differences in heart rates, respiration rates and cortisol levels before and during the tagging events were investigated. An overall significant decrease of 31.5% in respiration rate was found during the tagging event period, while mature porpoises respired significantly more often than immature individuals. Though significant differences in heart rates were found for some individuals, no general significant change for all animals was detected. We found no correlation between cortisol concentration and either heart rate or respiration rate, nor did we find any relationships between cortisol and month of year, sex and body length. As high individual variations occurred in response to tagging of harbour porpoises, it is not possible to give general advice based on the factors investigated, on how to reduce stress during handling. However, pouring water over the animal and lowering it into the water seem to stabilize a stressed animal. Therefore, general precaution and individual judgement based on experience is essential when handling wild harbour porpoises.

Expected Task Duration and Perceived Effort: An Attributional Analysis

1980 ◽  
Vol 2 (3) ◽  
pp. 227-236 ◽  
Author(s):  
Walter J. Rejeski ◽  
Paul M. Ribisl
Keyword(s):  
Perceived Exertion ◽  
Mental Fatigue ◽  
Treadmill Running ◽  
Ratings Of Perceived Exertion ◽  
Heart Rates ◽  
Task Duration ◽  
Perceived Effort ◽  
Attributional Analysis ◽  
Male Subjects

The purpose of this study was to examine the effects of anticipated task duration on ratings of perceived exertion during treadmill running. Male subjects.(N = 15) completed two separate runs on a motor-driven treadmill at 85% V02 max. During one trial, subjects ran for a period of 20 minutes, while for a second trial, subjects were led to believe that they would be running for 30 minutes. In each case, the trials were terminated at the 20-minute mark. Ratings of perceived exertion, heart rates, respiratory rates, and ventilatory minute volumes were collected across each trial. Results supported the supposition that the anticipation of continued performance mediated ratings of effort expenditure. This effect was obtained only during moderate work levels and was in contrast to research examining mental fatigue.

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