Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EXERTION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed2005

Self-regulated running using perceived exertion in children.

AIM: The aim of this study was to examine the ability of 5- to 7-year-old female (n=16) and male (n=16) children to use perceived exertion in order to self-regulate their running intensity. An estimation-production paradigm was used to determine if 1) self-regulation of exercise using OMNI Scale could be administered in young children, 2) children were able to distinguish 3 different intermittent exercise intensities and 3) gender would differentiate the use of perceived exertion. METHODS: Children underwent 1) 1 estimation trial and 2) 3 production trials. During the estimation trial, perceived exertion was estimated at the end of each stage of an incremental running field test. Then, during the production test, the children were requested to run in random order 300 m bouts on an outdoor track at an exercise intensity based on their interpretation of levels 2, 6 and 10 of the OMNI Scale. Heart rate was continuously recorded during both trials. RESULTS: Heart rate did not differ significantly between estimation and production trials at the level 2 (124.1 SD 6 vs 125.3 SD 4 bpm), 6 (164.9 SD 5 vs 166.2 SD 6 bpm) and 10 (200.9 SD 8 vs 203.1 SD 8) of the OMNI scale. Furthermore, HR responses at OMNI 6 were significantly (p<0.05) higher than OMNI 2, and OMNI 10 were significantly (p<0.05) higher that OMNI 6. No significant difference was found between female and male children. CONCLUSIONS: The present investigation supports the view that the young female and male children tested in this study were able to use perceived exertion to self-regulate during intermittent running exercises.

Analysis of Variance↗
PubMed2006

Cut-points to prevent low back injury due to force exertion at work.

Force exertion is related to low back injuries (LBI). This paper critically reviews the literature concerning cut-points for back force exertion, presents available guidelines in a concise manner, and identifies areas that need further research. The studies reviewed were grouped according to the criteria used to set the cut-point values. Most often cut-points differ than concur. The approach considering physiological, psychophysical, epidemiological, and biomechanical aspects of back force exertion meets the most known criteria and presents the lowest common denominator of instantaneous load for lifting tasks. Further experimental and epidemiological studies in peak load and cumulative exposure are necessary. Compound indices should also be developed for pushing, pulling, and carrying. Future indices should consider electromyographically determined fatigue, differential viscoelastic properties of tissues, aging, and the cross sectional area of back muscles. We hope that this paper contributes to a more systematic appraisal of back force exertion at work.

Alberta↗
PubMed1990

Anthropometry and knee exertion injuries incurred in a physical training program.

Factors causing predisposition to knee exertion injuries were sought by means of a questionnaire and detailed anthropometric measurements in 39 Finnish Army conscripts picked from a random sample of 56 army conscripts. The subjects consisted of two groups of 18- to 23-year-old conscripts; Group A comprised 29 subjects without knee exertion injuries and Group B 10 subjects who had experienced knee exertion injuries during the physical training program of the first eight weeks of military service. In Group A the physical activity level preceding the military service was somewhat higher than in Group B. In Group B the skeletal dimensions were longer and the body fat percentage was higher than in Group A. We conclude that big size of the subjects predisposed to knee exertion injuries during the training program.

Adolescent↗
PubMed1988

Fetal heart rate response to maternal exertion.

Doppler monitoring of fetal heart rates during maternal exertion has suggested that fetal bradycardia occurs frequently during vigorous exercise, causing concern for fetal safety. Doppler determination of fetal heart rate during vigorous maternal effort is difficult. To avoid motion artifact, we observed fetal heart rate using two-dimensional ultrasound and determined the incidence of fetal bradycardia in 45 pregnant women (age, 29.0 +/- 3.7 years [mean +/- SD]; gestational age, 25.2 +/- 3.0 weeks) during 85 submaximal and 79 maximal cycle ergometer tests. Average fetal heart rate did not change during exercise. A single episode of fetal bradycardia (heart rate less than 110 beats per minute for greater than or equal to 10 s) occurred during submaximal exertion during a maternal vasovagal episode. Sixteen episodes of fetal bradycardia were noted within three minutes after cessation of exercise, 15 of which followed maximal maternal effort. We conclude that brief submaximal maternal exercise up to approximately 70% of maximal aerobic power (maternal heart rate less than or equal to 148 beats per minute) does not affect fetal heart rate. In contrast to submaximal maternal exertion, maximal exertion is commonly followed by fetal bradycardia. This may indicate inadequate fetal gas exchange.

Adult↗
PubMed1987

Management of chronic exertional anterior compartment syndrome of the lower extremity.

Eighteen patients (28 compartments) with chronic exertional compartment syndrome and 14 normal asymptomatic volunteers (18 compartments) were studied. Evaluation included clinical assessment followed by quantitative determination of intracompartmental pressures as monitored by wick or slit catheters before and after exercise. Intramuscular pressures measuring greater than or equal to 10 mmHg at rest and/or greater than or equal to 25 mmHg five minutes after exercise were defined as abnormally elevated. The patients with chronic compartment syndrome described reproducible exertional anterolateral leg pain, and 39% of these patients had a fascial hernia. Such a defect was present in less than five percent of the normal volunteers. Nonsurgical treatment was selected by five patients and all five reported persistent inability to participate in athletics because of their exertional pain. Of the remaining 13 patients, 12 were treated by decompressive fasciotomy and 11 of the 12 (92%) had pain relief and increased exercise tolerance. A single patient had had fascial closure instead of fasciotomy, and this procedure produced an acute compartment syndrome. Effective treatment of the chronic compartment syndrome consists of reduction of exertional activities or surgical decompression by fasciotomy.

Adolescent↗
PubMed1982

Central signals of perceived exertion during dynamic exercise.

The purpose of this review is to examine the evidence that links specific physiological processes with central signals of perceived exertion during dynamic exercise. The physiological processes thought to be associated with a central signals of exertion include heart rate (HR), ventilation (VE), respiratory rate (RR), and oxygen uptake (VO2). Parallel changes in HR and ratings of perceived exertion (RPE) were not apparent when HR was manipulated experimentally. Heart rate does not appear to be associated with a strong central signal of exertion. Sensations of ventilatory function and discomfort are the only central signals that are consciously monitored. Corresponding changes in VE and RPE were noted when ventilatory drive was altered by hypnosis, induced erythrocythemia, hypoxia, or hyperoxia. Ventilation begins to provide potent sensory signals between 45-70% VO2max. Both the absolute and relative (percent VO2) oxygen uptake have been proposed as central signals. For a fixed VO2, RPE differed when comparisons were made between various experimental conditions. In contrast, RPE did not differ between conditions when expressed as a function of percent of VO2max. The relative VO2 is more likely to be associated with a strong sensory signal. Central signals involving VE and the relative VO2 are proposed to act as an amplifier that potentiates local signals in proportion to the aerobic metabolic demand.

Aerobiosis↗
PubMed1982

Differentiated ratings of perceived exertion during physical exercise.

The typical overall (undifferentiated) rating of perceived exertion (RPE) appears to represent an individual's integration of various physiological sensations that have different subjective weightings. Two categories of physiological factors have been suggested as major determinants of RPE during physical exercise. These two factors are a local factor that relates to sensations or feelings of strain from the exercising muscles and/or joints and a central factor relating primarily to cardiopulmonary sensations. This paper attempts to characterize the relative importance of the various physiological cues in the exertional rating pertinent to these local and central factors. The majority of the related literature suggests that local factors are usually perceived as dominant; however, recent findings that evaluate differentiated RPE during exercise at high altitude imply a greater importance for central factors. When a particular physiological cue is markedly altered over others during exercise, it appears that the resultant sensation can easily dominate the overall RPE. In contrast, when this particular cue is not changed during exercise, as the result of some experimental manipulation or intervention, then another cue can become pronounced. Finally, an experimental model for evaluating differentiated RPE that allows comparisons between local and central exertion and further comparison to the general or overall exertion is discussed.

Altitude↗
PubMed1995

Acute exertional rhabdomyolysis.

Acute exertional rhabdomyolysis is caused by a skeletal muscle injury that results in the release of myoglobin and other cellular contents into the circulatory system. Recent reports suggest that acute exertional rhabdomyolysis is more common and more serious than previously realized. Mild to moderate acute exertional rhabdomyolysis can result in hyperkalemia, hypernatremia, lactic acidosis and hyperphosphatemia. Disseminated intravascular coagulation, renal failure and compartmental syndrome may also occur. The physician should maintain a high index of suspicion for acute exertional rhabdomyolysis in patients who present with symptoms of an overexertion injury, most commonly pain and swelling in the affected muscles. Special attention should be given to evaluating the history for occupational, recreational, environmental and medical risk factors for rhabdomyolysis. Screening may be performed with a simple urine dipstick test; if the urine is orthotoluidine-positive, the diagnosis should be confirmed with measurement of the serum creatine kinase level. Early intervention with aggressive hydration and close monitoring for metabolic, renal or hematologic complications may prevent serious injury or death.

Acute Disease↗
PubMed1994

Prescribing exercise intensity for healthy adults using perceived exertion.

Rating of perceived exertion (RPE) is endorsed by the American College of Sports Medicine as a useful adjuvant for prescribing and monitoring exercise intensity. In this paper, I describe a rationale for the use of RPE and other exertional symptoms as an alternative to traditional exercise prescription procedures for healthy adults. Errors associated with using RPE for producing exercise intensity are discussed along with limitations with the use of HRReserve as the standard for judging the accuracy of RPE for prescribing relative exercise intensity. The concept of preferred exertion is discussed as a prescription paradigm that is complementary to the use of perceived exertion and physiological indicators of relative exercise intensity. Important areas that have not received enough research attention are summarized.

Adult↗
PubMed1993

Exertional gastroesophageal pH-metry: a new provocative physiological test in the diagnosis of chest pain.

With the aim of determining the value of physical exercise as a provocative test for chest pain associated with gastroesophageal reflux, 67 patients presenting non-cardiac chest pain (normal coronary angiograms and no functional coronary artery alterations) with different characteristics (group A: at rest; group B: exertional or mixed-type) underwent exercise tests during 24-hour gastroesophageal pH-metry associated with electrocardiographic (EKG) monitoring. Thirty-four patients in group A (73.4%), and 12 in group B (57%) showed pathological reflux on 24-hour gastroesophageal pH-metry. Twelve patients in group A (25%) and 6 in group B (28.5%) (total ratio: 26.8%) presented positive responses to exercise, with concomitant occurrence of gastroesophageal reflux, typical pain, without EKG ischemic signals. Exertional pH-metry allowed to reach diagnostic certitude in 10 (14.9%) of 67 patients, 9 presenting 24-hour pH-metry results that only suggested "possible" diagnosis, and 1 without either pathological reflux or pain during prolonged monitoring: all these patients belonged to group A. The repetition of the test showed total reproducibility of the results, with "fixed thresholds" of exercise in 11 of 18 subjects (61.1%). These data suggest the usefulness of grouping different diagnostics (24-hour EKG, pH-metry and exertional test) to increase diagnostic certitude, mainly in patients with primary angina. Exertional pH-metry shows to be an efficacious provocative test, and the only based on a physiological stimulus.

Adult↗
PubMed1987

Pressures exerted by experimental cholesteatomas.

Previous studies have shown that transmitted pressure may be an important factor in the induction of osteoclastic bone resorption by cholesteatoma. However, the ability of cholesteatomas to actually exert pressure on adjacent structures has not been studied. Implantable pressure gauges were used to measure static pressure exerted by induced gerbilline cholesteatomas. Cholesteatomas were found to exert pressures between 1.31 mm Hg and 11.88 mm Hg. Osteoclastic bone resorption was observed in areas where the pressure gauge transmitted these pressures to bone. Thus, pressure exerted by an expanding cholesteatoma may be an important factor in the induction of osteoclastic bone resorption.

Animals↗
PubMed2003

Abnormal coupling of knee and hip moments during maximal exertions in persons with cerebral palsy.

The motions of lower-limb extension, adduction, and internal rotation are frequently coupled in persons with cerebral palsy (CP) and are commonly referred to as an extension synergy. However, the underlying joint moments that give rise to these coupled motions are not well understood. We hypothesized that maximal voluntary exertions in a direction of one component of a synergy (e.g., hip extension) would result in the concurrent presence of other components of the synergy in subjects with CP but not in control subjects. To test this hypothesis, we measured three-dimensional moments about the hip and knee as nine subjects with spastic CP and six control subjects performed maximal isometric exertions of the hip and knee flexors and extensors. During maximal hip extension exertions, control subjects simultaneously generated a knee flexion moment, whereas CP subjects generated a knee extension moment (P < 0.05) and a larger hip internal rotation moment than did controls (P < 0.05). During maximal knee extension exertions, control subjects generated a hip flexion moment, whereas CP subjects generated a hip extension moment (P < 0.05). The patterns of joint moments generated by CP subjects are consistent with an extension synergy and may underlie the coupled motion patterns of the lower extremity in such persons.

Adolescent↗
PubMed1990

Blood glucose extraction as a mediator of perceived exertion during prolonged exercise.

The effect of blood glucose extraction on the perception of exertion was examined during prolonged arm exercise. Eight male subjects consumed in counter-balanced order a standard daily diet containing either (1) 75 g dihydroxyacetone and 25 g sodium pyruvate (DHAP) or (2) an isocaloric amount of placebo, to manipulate blood glucose extraction. Following each 7-day diet, subjects exercised to exhaustion at 60% of peak arm oxygen consumption. Ratings of perceived exertion (Borg, CR-10 scale) were obtained for the arms (RPE-A), legs (RPE-L), chest (RPE-C) and overall body (RPE-O) every 10 min of exercise. After 60 min of continuous exercise, blood samples were drawn from the radial artery and axillary vein. Ratings of perceived exertion did not differ between trials during the first 50 min of exercise. At the 60-min time point, perceived exertion was lower (P less than 0.01) in the DHAP than placebo trials for the arms (RPE-A: 4.25 vs 5.50) and overall body (RPE-O: 3.25 vs 4.00). These differences persisted throughout exercise. RPE-L and RPE-C did not differ between trials. Whole-arm arterial-venous glucose difference was higher (P less than 0.05) in the DHAP (1.00 mmol.l-1) than placebo (0.36 mmol.l-1) trials, as was fractional extraction of glucose (22.5 vs 9.0%). Respiratory exchange ratio was the same between trials. Triceps muscle glycogen was (1) higher in the DHAP than placebo trial at pre-exercise (P less than 0.05), (2) decreased during exercise and (3) did not differ between trials at exercise termination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1996

The influence of task resistance on the characteristics of maximal one- and two-handed lifting exertions in men and women.

Dynamic lifting strength was assessed at lift velocities ranging from 0 to 1 m.s-1 using a hydrodynamometer in which the viscous resistance to motion could be preset. Nine men and nine women performed one- and two-handed dynamic exertions against low, medium, and high resistances. The subjects were required to lift as forcefully and as fast as possible from a height of 400 mm to just above head height. The instantaneous forces recorded at knee, knuckle, hip, shoulder, elbow, and head heights were compared with those obtained during maximal one- and two-handed isometric lifts performed at the same heights. The position of peak force relative to stature was lower for one-handed lifts (35.9% of stature) than for two-handed lifts (38.4% of stature) (P < 0.005), but was unaffected by lift resistance (P > 0.05) and subject sex (P > 0.05). Lifting forces during two-handed exertions were on average 1.5 times greater than for one-handed exertions (P < 0.0001). However, the difference in the strength of one- and two-handed lifts was highly dependent on hand height (P < 0.0001) and task resistance (P < 0.005), and was greater for the men than for the women (P < 0.001). When static lifting strength was measured at heights relative to stature and normalized by dividing by body weight, there was no significant difference in performance between the men and the women [mean normalized female:male: (f:m) strength ratio = 0.76, P > 0.05]. Under dynamic conditions the sex difference in lifting performance was pronounced (mean normalized f:m strength ratio = 0.68, P < 0.01), especially for power output (mean f:m power.unit body weight-1 ratio = 0.52, P < 0.005). The proportion of generality (r2 x 100) between dynamic and static lifting strength was found to range between 63% and 87%. These data suggest that the dynamic and static tests of lifting strength measured a common, intrinsic ability to produce maximal lifting forces. The finding that sex differences in strength are dependent on whether the exertion is static or dynamic has important implications for biomechanical models of human strength.

Adult↗
PubMed2005

Effects of pressure exerted on the skin by elastic cord on the core temperature, body weight loss and salivary secretion rate at 35 degrees C.

Effects of pressure exerted on the skin by elastic cord on the core temperature, body weight loss and salivary secretion rate were studied under conditions of ambient temperature of 35 degrees C and a relative humidity of 60%. Twelve healthy females, aged 18-23 years, served as subjects. The subjects entered a bioclimatic chamber and rested quietly in a chair for 80 min. Then, skin pressure was exerted by applying elastic cord (8.5 mm wide) to six different skin areas, such as axilla, under-bust, waist, inguines, thighs and ankles. The values of skin pressure by elastic cord ranged from 11.9 to 33.3 g/cm(2). In the control experiment, wrapping with an elastic cord was loosely performed without any skin pressure. Rectal and skin temperatures, body weight loss by sweating and salivary secretion rate were measured throughout the 160 min experimental period. Core temperature increased more significantly under pressure exerted on the skin. Body weight loss by mainly sweating and salivary secretion rate were significantly suppressed under pressure exerted on the skin. We discussed the physiological mechanisms in terms of suppression of central nervous activity as to why significant increase of core temperatures, inhibition of body weight loss mainly by sweating and of salivary secretion rate occurred, and furthermore practical significance of these findings for impairment of digestion, swallowing, vocalizing, defense against disease bacteria and sport activity.

Adolescent↗
PubMed1994

Hemodynamic and hemostatic responses to morning and evening exertion in systemic hypertension and implications for triggering of acute cardiovascular disease.

The increased morning frequency of cardiovascular disease onset has created concern that morning exertion promotes greater risk than evening exertion. The physiologic responses to isometric exercise (handgrip) in the morning (9 A.M.) versus the evening (6:30 P.M.) were compared in 15 subjects with mild hypertension. Isometric exercise produced similar increases at both times of the day (morning vs evening) in systolic arterial pressure (31 +/- 4 vs 35 +/- 4 mm Hg, p = NS) and heart rate (7 +/- 1 vs 8 +/- 1 beats/min, p = NS). It also produced similar increases in fibrinolytic activity (reduction in euglobulin clot lysis time) at both times of the day (-53 +/- 27 vs -53 +/- 21 minutes). However, because basal fibrinolytic activity was lower in the morning than in the evening (euglobulin clot lysis time 364 +/- 45 vs 220 +/- 33 minutes, p < 0.01), peak fibrinolytic activity after stress was also lower in the morning (312 +/- 44 vs 176 +/- 27 minutes, p < 0.01). The present study demonstrates that in subjects with hypertension, the hemostatic and hemodynamic responses to handgrip are not greater during morning versus evening exertion. This finding, plus the overall benefits of regular exercise and the low absolute risk of an event during exercise, suggests that timing of exertion is not of critical importance. However, to obtain a definitive answer to this question, further studies are needed using different potential triggers and subject populations.

Adult↗
PubMed1996

A method for measuring external loads during dynamic lifting exertions.

Biomechanical analyses of lifting exertions often require measured values of applied trunk moments and forces as baseline or validation data. Accurate measures of the trunk kinetic data are difficult to achieve from dynamic exertions without significant approximation, cost, or motion constraints. The purpose of this effort was to develop and validate a means to directly measure multi-dimensional, trunk moments which occur during dynamic lifting exertions. Force plate reaction loads coupled through a lower-body isolation structure designed to fasten the hips and legs into a known static position, were employed to compute the moment vectors about the lumbar spine. Results demonstrate the applied moments about the lumbo-sacral junction of the spine can be accurately measured from a single force plate, allowing biomechanical evaluation of dynamic lifting exertions without constraining the motions of the upper body.

Adult↗
PubMed1997

Oxytocin releases atrial natriuretic peptide from rat atria in vitro that exerts negative inotropic and chronotropic action.

Our previous experiments suggested that natriuresis induced by blood volume expansion, was brought about by oxytocin (OT)-stimulated atrial natriuretic peptide (ANP) release from the right atrium. We hypothesized that the ANP released might exert effects on the atrium itself and therefore carried out in vitro experiments to test this hypothesis. Heart rate and isometric tension were recorded from isolated rat atria mounted in an organ bath. Oxytocin exerted a dose-related, negative chrono- and inotropic effect with a minimal effective concentration (MEC) of 3 microM, 10-fold higher than required for ANP to exert comparable effects. The effects of OT were not blocked by atropine suggesting that they were not mediated via release of acetylcholine. Eight-bromoguanosine 3'-5'-cyclic monophosphate (cGMP) had similar effects to those of OT and ANP, suggesting that the effects of ANP were mediated by cGMP. When isolated ventricles, left or right atria, were incubated in vitro, OT had a dose-related effect to stimulate the release of ANP into the medium only from right atria with a MEC of 0.1 microM. A specific OT antagonist, F792 (1 microM), inhibited basal release of ANP and blocked the stimulatory action of OT on ANP release. The results support the hypothesis that OT, acting on its putative receptors in the right atrium, stimulates the release of ANP which then exerts a negative chrono- and inotropic effect via activation of guanylyl cyclase and release of cGMP. The ability of the oxytocin antagonist to reduce basal release of ANP from atria incubated in vitro supports the hypothesis that these effects could be physiologically significant. We hypothesize that blood volume expansion via baroreceptor input to the brain causes the release of OT which circulates to the heart and stimulates the release of ANP from the right atrium. This ANP then has a negative ino- and chronotropic effect in the atrium and possibly a negative inotropic effect in the right ventricle, left atrium and left ventricle, to produce an acute reduction in cardiac output that, coupled with its peripheral vasodilating actions, causes a rapid reduction in effective circulating blood volume. The ANP released would also act on the kidneys to cause natriuresis and ANP acts within the brain to inhibit water and salt intake leading to a gradual recovery of circulating blood volume to normal.

Animals↗