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PubMed2000

Triggering of sudden death from cardiac causes by vigorous exertion.

BACKGROUND: Retrospective and cross-sectional data suggest that vigorous exertion can trigger cardiac arrest or sudden death and that habitual exercise may diminish this risk. However, the role of physical activity in precipitating or preventing sudden death has not been assessed prospectively in a large number of subjects. METHODS: We used a prospective, nested case-crossover design within the Physicians' Health Study to compare the risk of sudden death during and up to 30 minutes after an episode of vigorous exertion with that during periods of lighter exertion or none. We then evaluated whether habitual vigorous exercise modified the risk of sudden death that was associated with vigorous exertion. In addition, the relation of vigorous exercise to the overall risk of sudden death and nonsudden death from coronary heart disease was assessed. RESULTS: During 12 years of follow-up, 122 sudden deaths were confirmed among the 21,481 male physicians who were initially free of self-reported cardiovascular disease and who provided information on their habitual level of exercise at base line. The relative risk of-sudden death during and up to 30 minutes after vigorous exertion was 16.9 (95 percent confidence interval, 10.5 to 27.0; P<0.001). However, the absolute risk of sudden death during any particular episode of vigorous exertion was extremely low (1 sudden death per 1.51 million episodes of exertion). Habitual vigorous exercise attenuated the relative risk of sudden death that was associated with an episode of vigorous exertion (P value for trend=0.006). The base-line level of exercise was not associated with the overall risk of subsequent sudden death. CONCLUSIONS: These prospective data from a study of U.S. male physicians suggest that habitual vigorous exercise diminishes the risk of sudden death during vigorous exertion.

Adult↗
PubMed1996

Self-reported physical exertion in geriatric care. A risk indicator for low back symptoms?

STUDY DESIGN: The study group consisted of 131 female nursing aides who took part in an intervention program with physical training or education. Assessments were performed before the intervention program and after 6 months. At follow-up evaluation, 91 nursing aides remained in the study. OBJECTIVES: To examine if perceived physical exertion was a risk indicator for low back symptoms, and to examine the relationship between perceived physical exertion, aerobic capacity, back endurance, psychological demands, and job control. SUMMARY OF BACKGROUND DATA: Perceived physical exertion frequently is assessed in epidemiologic studies concerning low back symptoms. More information about the relationship between perceived exertion, other potential risk indicators, and symptoms may provide opportunities for effective prevention of symptoms. METHODS: Assessments were obtained by questionnaires and physical capacity tests. RESULTS: The nursing aides who reported high physical exertion and were 45 years of age or older were at greater risk in the follow-up period for reporting new symptoms, continued symptoms with the same intensity, or more intense symptoms from the low back (rate ratio, 3.01; 95% confidence interval, 1.1-8.2). The exposure variable correlated most strongly (r = 0.4) with perceived physical exertion was psychological demands. CONCLUSIONS: The results indicated being aged 45 years or older, combined with high perceived physical exertion, was a risk indicator for low back symptoms. A relationship between perceived physical exertion and psychological demands was observed, but there was no influence of physical capacity on perceived physical exertion.

Adult↗
PubMed1988

Impaired left ventricular function during exercise in coronary artery disease and exertional hypotension.

To characterize the hemodynamic abnormalities responsible for exertional hypotension coronary artery disease, we studied 11 patients with exertional hypotension during supine cycle ergometer exercise, defined as greater than 10 mm Hg decrease in systolic blood pressure during exercise, and 11 patients without exertional hypotension (controls). Patients were similar with respect to age, left ventricular ejection fraction at rest, and the intensity of exercise relative to maximal treadmill exercise capacity. Peak exercise ejection fraction, determined by radionuclide ventriculography, was significantly lower in patients with, than in those without exertional hypotension (50 +/- 3 vs. 56 +/- 3%; p less than 0.025). Ejection fraction and stroke volume decreased with exercise in patients with exertional hypotension but not in the controls even though changes in end-diastolic volume and mean blood pressure were similar in both groups. Peak exercise systolic blood pressure and rate pressure product were significantly lower in the patients with exertional hypotension than those without. The exercise-induced regional left ventricular contraction abnormalities were more prominent, extensive and frequent in patients with exertional hypotension than controls. Impairment of left ventricular contractile function was further evident by an abnormal end-systolic volume-systolic blood pressure relation in patients with exertional hypotension. These patients attained a much smaller increase in systolic blood pressure compared with controls despite no statistically significant differences in end-systolic volume response to exercise. These findings suggest that exertional hypotension in patients with ischemic heart disease is associated with exercise-induced left ventricular systolic dysfunction secondary to extensive myocardial ischemia.

Coronary Disease↗
PubMed1993

Perceived exertion. Antecedents and applications.

The field of perceived exertion has largely concerned itself with the problem of identifying the primary antecedents to this psychophysiological phenomenon. A vast literature has evolved addressing this problem, but it is fraught with contradictions. At this stage a comprehensive theory of perceived exertion does not exist. It is generally accepted that perception of exertion is dominated by physiological determinants. Physiological sensory cues have been separated into 2 categories: local factors (sensations from the working muscles and joints), and central factors (sensations from the cardiopulmonary system). Major reviews in this area generally agree that local factors dominate perception of exertion. Recent work in perceived exertion has placed an emphasis on examining the contributing psychological factors. Research into the psychological factors affecting perceived exertion has been highly fragmented with no apparent theoretical framework as a base. At the same time it is clear that an integration of psychological and physiological variables is required to obtain theoretically meaningful knowledge of this multidimensional construct. The assumed dominance of physiological factors has been challenged by the contention that in field situations, in which a variety of social psychological influences operate, psychological determinants of perceived exertion may be vastly more influential than previously estimated. Identification of the primary determinants of perceived exertion and knowledge of how these factors are integrated is vital for a concrete theory of perceived exertion to evolve.

Exercise Therapy↗
PubMed1996

[Onset of dyspnea on exertion in elderly and young patients with congestive heart failure].

We previously reported that dyspnea on exertion in patients with congestive heart failure was not associated with pulmonary function ar rest, but was associated with the appearance of the anaerobic threshold and with the respiratory compensation point during exercise. Here we described a study of the influence of aging on the onset of dyspnea on exertion in elderly and in young patients with congestive heart failure. A total of 53 patients were studied: 35 were less than 65-year-old (average age, 47-year-old; 19 men and 16 women) and 18 were more than 65-year-old (average age, 70-year-old; 13 men and 5 women). All patients underwent maximal graded exercise testing on a bicycle ergometer. The workload increased according to a ramp protocol, and perceived exertion was evaluated with the Borg scale. The anaerobic threshold, the respiratory compensation point, and the peak VO2 were recorded. Values of 13 (somewhat hard) and 17 (very hard) on the Borg scale were considered to mark the start of dyspnea on exertion and an increase in dyspnea on exertion respectively. In the young patients, dyspnea on exertion began at about the time that the anaerobic threshold was reached, and it increased at about the time that the respiratory compensation point was reached. In contrast, elderly patients dyspnea on exertion began 70 seconds after the anaerobic threshold was reached, and it increased 30 seconds after the respiratory compensation point was reached. The VO2 at the start of dyspnea on exertion and the VO2 at the anaerobic threshold correlated more closely in the young patients than in the old patients. The same was true of the VO2 at the time that dyspnea on exertion increased and the VO2 at the respiratory compensation point. These findings suggest that elderly patients with congestive heart failure are less sensitive to the stimuli that cause dyspnea than are young patients.

Adolescent↗
PubMed1994

A characteristic change in ventilation mode during exertional dyspnea in patients with chronic heart failure.

Although exertional dyspnea is an important symptom limiting daily lives in patients with chronic heart failure, there is no objective assessment of this symptom. To characterize the exertional dyspnea, ventilatory responses to exercise were studied in relation to exertional dyspnea. Gas exchange data were obtained during a maximal bicycle exercise in 43 patients with chronic heart failure and 20 normal subjects. In addition to standard ventilatory variables, the ventilation mode was assessed from the tidal volume-ventilation rate (VT-f) relationship. The exercise was performed again after sublingual administration of 5 mg of isosorbide dinitrate. In normal subjects, the f and VT increased almost proportionally with exercise intensity. In 17 (85 percent) of 20 patients with exertional dyspnea, the VT-f relationship abruptly lost linearity at the onset of exertional dyspnea. This change resulted from an inadequate increase in VT and a further increase in f. In 8 of these 17 patients, isosorbide dinitrate improved exertional dyspnea with normalization of the VT-f relationship; however, in 9 patients whose dyspnea was not improved, the abnormal VT-f relationship was unaltered. Only 2 (9 percent) of 23 patients without exertional dyspnea showed the abnormal VT-f relationship. Other ventilatory variables were not different between patients with and without dyspnea. Thus, exertional dyspnea is characterized by simultaneous appearance of rapid and shallow ventilation. The VT-f relationship appears to be a simple and useful objective assessment of exertional dyspnea in patients with chronic heart failure.

Dyspnea↗
PubMed2003

Perceived exertion and maximal quadriceps femoris muscle strength during dynamic knee extension exercise in young adult males and females.

The objectives of the present study were to: (1) examine perceived exertion across different target voluntary-contraction intensities; (2) compare perceived exertion ratings with actual target intensities, and (3) compare perceived exertion ratings between males and females. Subjects for this study included 30 healthy, college-aged male (n=15) and female (n=15) volunteers. All subjects were free of orthopedic, cardiopulmonary, systemic and neurological disease. Subjects were evaluated for their one-repetition maximum (1-RM) during inertial knee extension exercise. All subjects then completed, in a random order, two sub-maximal inertial contractions at 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of their 1-RM. Perceived exertion was measured by asking subjects to provide a number that corresponded to the feelings in their quadriceps after completion of the two repetitions, by viewing a modified category-ratio (CR-10) scale. The results showed that males lifted a significantly greater absolute (P<0.05) and relative (P<0.05) amount of mass than females; allometric-modeled strength values also demonstrated significant sex differences. The results revealed a significant intensity main effect (P<0.001) but no significant gender main effect (P=0.97) nor intensity-by-gender interactions (P=0.50) for the perceived exertion responses. The findings demonstrated that perceived exertion was significantly (P<0.05) lower than the specific expected values on the CR-10 scale from 10% to 60% of 1-RM, but was not different from 70% to 90% 1-RM. The results revealed that the increase in perceived exertion was fit to both linear and quadratic trends, and that the exponent of the power function was found to be 1.437 (SD 0.22) for the males, and 1.497 (0.295) for the females. The major findings demonstrate that although males were able to lift more absolute and relative mass than females, the perceptual response to relative load was similar between genders. The increase in perceived exertion, as a function of relative load, showed a strong linear trend; however, enhanced perceptual sensitivity at high contraction intensities was evident from the positively accelerating power function.

Adult↗
PubMed2000

Fitness and perceived exertion in patients with fibromyalgia syndrome.

OBJECTIVE: The aim of this study was to evaluate the cardiorespiratory fitness and perceived exertion of female patients with fibromyalgia syndrome (FMS) compared with that of healthy female subjects. DESIGN AND SUBJECTS: This was designed as a cross-sectional case-control study, with a consecutive sample of 30 female patients with FMS and an age-matched control group of 67 healthy female subjects. SETTING: This study was conducted at the multidisciplinary pain center of a university hospital in a city of more than 1 million inhabitants. OUTCOME MEASURES: A cardiorespiratory fitness index (PWC65%/kg) and an original perceived exertion index (B65%) were obtained from the heart rates and perceived exertions scored on a 10-point Borg scale during a submaximal cycle ergometer test. Average indexes for the FMS patients and control subjects were compared. RESULTS: The mean cardiorespiratory fitness index of the FMS patients was not significantly different from that of the controls. The mean perceived exertion index in the FMS patients was significantly greater than that of the controls, meaning that the FMS patients systematically reported higher ratings of perceived exertion during exercise. CONCLUSIONS: Cardiorespiratory fitness, as expressed by a submaximal work capacity index, seems normal in female patients with FMS compared with age- and sex-matched healthy individuals. The fact that FMS patients overscore their perception of exertion may be due to a greater overlap of peripheral pain and perceived exertion perceptions during exercise. This observation should be noted when using perceived exertion scores to prescribe and monitor exercise in FMS patients.

Adult↗
PubMed2002

Exertional dizziness and autonomic dysregulation.

OBJECTIVES: To define the clinical characteristics and treatment of dizziness induced by physical exertion and to investigate autonomic nervous system function in exertional dizziness. STUDY DESIGN: Retrospective case series from a review of 1400 patients evaluated for dizziness at a neurotology referral center, identifying those with predominantly exertional symptoms. METHODS: Records of patients with exertional dizziness were screened to eliminate those with known vestibular deficits, cardiopulmonary illnesses, and psychiatric disorders. The clinical characteristics, evaluation results, and treatment of nine patients with purely exertional dizziness were described. RESULTS: The cohort included 4 male and 5 female patients (age range, 13-53 y) with symptoms for 1 to 8 years. Only one patient had a history of autonomic symptoms: phlebotomy-induced syncope in childhood. No patient was taking medications that caused dizziness or orthostasis. All patients experienced "spacey" or "foggy" head sensations without vertigo during exertion. Provocative activities ranged from standing upright for extended periods to running and swimming. On examination, voluntary hyperventilation provoked moderate symptoms in all patients (without nystagmus or anxiety), although no patient had spontaneously occurring, hyperventilation-related complaints. Seven patients underwent autonomic testing. Tilt table tests (n = 5) produced severe symptoms in one patient and mild symptoms in two patients. Sodium lactate infusions (n = 6) provoked marked symptoms in four patients and moderate symptoms in one patient. All were treated for autonomic dysregulation. Seven patients improved substantially and resumed all of their premorbid activities. Two improved slightly. CONCLUSIONS: In nine patients with exertional dizziness, autonomic challenges were provocative, and medications for autonomic dysregulation were effective. Exertional dizziness may be a clinical manifestation of autonomic nervous system dysregulation.

Adolescent↗
PubMed2004

Gender differences in perceived exertion during fatiguing knee extensions.

PURPOSE: To examine gender differences in knee extensor strength, fatigue, and perceived exertion during a single set of continuous dynamic knee extensor contractions. METHODS: Fifteen men and 15 women were evaluated for their one-repetition maximum (1RM) during a single-leg, inertial knee extension with their right leg. All subjects then completed a single set of repeated knee extensions with a load equivalent to 50% of their 1RM to failure. Subjects lifted the weight by performing a knee extension, held the weight with the knee extended for 1-2 s, and then lowered the weight in a slow and controlled manner. Perceived exertion was measured after completion of each repetition, by viewing a modified Borg category-ratio (CR-10) scale. Perceived exertion responses were standardized across subjects via linear interpolation and power function modeling. The linear interpolated perceived exertion estimates were then examined for linear, quadratic, and cubic trends across the repetitions. RESULTS: Men lifted a significantly greater amount of mass than women, when corrected for body mass. Men and women did not differ significantly in the number of repetitions performed to failure. Women displayed significantly higher power function exponents for the perceived exertion response than men (0.72 +/- 0.16 and 0.57 +/- 0.16, respectively) and demonstrated statistically nonsignificant greater increases in perceived exertion than men across the repetitions. CONCLUSIONS: The major findings of this study indicated that: 1) men inherently possessed greater knee extensor strength than women; 2) submaximal fatiguing knee extensor performance did not differ between genders; 3) model selection had a significant impact on standardizing perceived exertion estimates; and 4) subtle gender differences in the perceived exertion response may have existed during submaximal, fatiguing resistance exercise.

Adult↗
PubMed2001

The influence of sensory cues on the perception of exertion during exercise and central regulation of exercise performance.

The perception of effort during exercise and its relationship to fatigue is still not well understood. Although several scales have been developed to quantify exertion Borg's 15-point ratings of perceived exertion (RPE) scale has been adopted as a valid and reliable instrument for evaluating whole body exertion during exercise. However, Borg's category-ratio scale is useful in quantifying sensations of exertion related to those variables that rise exponentially with increases in exercise intensity. Previous research has examined the extent to which afferent feedback arising from cardiopulmonary and peripheral variables mediates the perception of exertion. However, the literature has not identified a single variable that consistently explains exertion ratings. It is concluded that effort perception involves the integration of multiple afferent signals from a variety of perceptual cues. In a process defined as teleoanticipation, the changes in perceived exertion that result from these afferent signals may allow exercise performance to be precisely regulated such that a task can be completed within the biomechanical and metabolic limits of the body. The accuracy with which individuals can regulate exercise intensity based upon RPE values, the decrease in muscle recruitment (central drive) that occurs before fatigue, and the extent to which perceived exertion and heart rate can be altered with hypnosis and biofeedback training all provide evidence for the existence of such a regulatory system. Future research is needed to precisely quantify the extent to which efferent feedforward commands and afferent feedback determine pacing strategies such that an exercise event can be completed without irreversible tissue damage.

Biomechanical Phenomena↗
PubMed2002

Ratings of perceived exertion during low- and high-intensity resistance exercise by young adults.

Ratings of perceived exertion (RPE) are commonly used to monitor the intensity of aerobic exercise. Whether ratings of perceived exertion can be used similarly during resistance exercise is unclear. To examine this question, perceived exertion was measured at 30% and 90% of the one-repetition maximum (1-RM), while holding work constant between intensities. Ratings for the active muscles and for the overall body were examined during both intensities. 10 male (age=23.2 +/- 3.6 yr.) and nine female (age=21.8 +/- 2.7 yr.) volunteers underwent a one-repetition maximum procedure for each of the following exercises: bench press, leg press, latissimus pull down, triceps press, biceps curl, shoulder press, and calf raise. All subjects then completed two experimental trials on separate days. The high-intensity trial consisted of one set of five repetitions at 90% of the one-repetition maximum. The low-intensity trial consisted of one set of 15 repetitions at 30% of the one-repetition maximum. Active muscle and overall body ratings of perceived exertion were obtained immediately at termination of each of the seven exercises at both intensities. A two-factor (RPE x Intensity) repeated-measures analysis of variance was performed separately for each exercise. Both active muscle and overall body ratings of perceived exertion were higher (p<.01) for the high-intensity trial than for the low-intensity trial. Active muscle ratings were higher (p<.01) than overall body ratings for all exercises. Ratings of perceived exertion during resistance exercise are related to intensity of the resistance exercise (percentage of the one-repetition maximum). This information suggests that ratings of perceived exertion can provide information regarding the intensity of resistance exercise. Furthermore, sensations of exertion in the active muscles during resistance exercise are greater than sensations for the overall body.

Adult↗
PubMed2004

Anchoring procedures in reliability of ratings of perceived exertion during resistance exercise.

Although the validity of perceived exertion as a method of monitoring the intensity of resistance exercise has been established, little is known about the test-retest reliability of ratings of perceived exertion during resistance exercise. Specifically, it is unknown whether the use of different anchoring procedures influences the reliability of ratings of perceived exertion. 30 men were assigned to an Exercise, Memory, or combined Exercise and Memory anchoring group. Participants completed an assessment of maximal leg-extension strength and were introduced to the Borg 15-category rating of perceived exertion scale through anchoring procedures that varied across groups. During two sessions of resistance exercise, participants rated active muscle perceived exertion after performing one repetition of the leg-extension exercise at 40%, 50%, 60%, 70%, 80% and 90% of the one-repetition maximum. A three-factor (Group x Intensity x Session) analysis of variance was performed to examine the perceived exertion data. Perceived exertion increased significantly (p<.01) with increasing exercise intensity in all groups and in both sessions. Mean ratings did not differ significantly among groups. Reliability was assessed for each group. Intraclass correlation coefficients ranged from .07 to .80 and percent agreement ranged from 60% to 90%. The results indicate that the reliability of ratings of perceived exertion during resistance exercise is acceptable regardless of the type of anchoring procedures used.

Adult↗
PubMed1982

Perceived exertion during patient lifts. An evaluation of the importance of various factors for the subjective strain during lifting and carrying of patients. A study at a geriatric hospital.

Model experiments and practical studies of patient lifts were carried out with the aim of finding a method for assessing perceived exertion during various types of patient lifts. In the model experiments perceived exertion was rated on the RPE (Borg) scale under standardized conditions with variation of the subject's working posture and the load to be lifted. A strong correlation was found between increased perceived exertion and an un-optimal posture and heavy load respectively. In the practical study of patient lifts the following eight variables were rated: posture, acceleration, the patient's weight, time needed for the lift, the load, patient cooperation, the moment about the fulcrum and the possibilities of getting a good hold. The subjects were asked to rate the perceived exertion on the RPE scale. Six common types of patient lifts were studied. By multiple regression analysis the different variables were analysed in relation to perceived exertion. Strong correlations were found between different variables and perceived exertion, with some variation between the different types of patient lifts. The perceived exertion in various types of patient lifts can therefore be characterized by a small number of variables (the most strongly correlated). By choosing the most characteristic variables for each patient lift, the method can be utilized to study changes in the perceived exertion for different types of patient lifts when the external conditions during the lift are changed.

Adult↗
PubMed2002

PVC tracheal tubes exert forces and pressures seven to ten times higher than silicone or armoured tracheal tubes--an in vitro study.

PURPOSE: Many types of tracheal tubes (TT) including silicone, polyvinylchloride (PVC) and armoured have been used for blind tracheal intubation (TI) via the intubating laryngeal mask airway (ILMA) and may cause trauma to the airway. We examined the maximal in vitro forces and pressures exerted by the tip of various TT as it exits the ILMA. METHODS: Silicone, PVC and armoured TT were studied. A #5 ILMA was secured on a wooden platform. With the use of a Harvard pump, force was applied to push the TT through the ILMA at 0.34 cm*sec(-1). Forces exerted to push the TT and forces exerted by the TT tips on distal objects were calculated using proximal and distal pressure manometres. The areas of contact between the distal TT tips and the distal objects were measured by planimetry of an imprint. The final pressures exerted by the TT tips on a fixed distal object were calculated by dividing the forces exerted by the areas of contact. RESULTS: When compared to silicone and armoured TT, PVC TT exerted seven to ten times higher forces and pressures on distal objects. (P < 0.05). Heating PVC TT and inserting PVC TT with reverse curvature to the ILMA did not decrease the forces and pressures exerted by the distal tip. CONCLUSION: The high forces and pressures exerted by PVC TT may theoretically contribute to increased morbidity to patients' airway and esophagus. Caution should be exercised before attempting blind TI via the ILMA with a PVC TT.

Intubation, Intratracheal↗
PubMed2000

Hemiplegic migraine induced by exertion.

BACKGROUND: It is known that exertion can aggravate migraine headache. However, the relationship between exertion and migraine aura is unknown. OBJECTIVE: To study the relationship between exertion and migraine aura. DESIGN: Case report. SETTING: Tertiary care hospital. PATIENT: A 67-year-old man presented with recurrent attacks of exertion-induced hemiplegic migraine. Since the hemiparetic attacks were exertion induced, they were initially ascribed to recurrent transient ischemic attacks. However, the clinical picture, normal findings on cerebral angiography and neuroimaging (during the period of hemiparesis), lack of response to treatment with antiplatelets and anticoagulants, and successful treatment with verapamil suggested that the hemiparesis was not due to ischemia, but was indeed a migraine aura. We suggest that exertion induced the aura of hemiparesis by lowering the threshold for the development of cortical spreading depression. Even though our patient had no family history of hemiplegic migraine, a mutation in an ion channel gene (eg, the CACNA1A gene on chromosome 19) might account for his episodic attacks. CONCLUSION: Migraine aura should be included in the differential diagnosis of exertion-induced focal neurologic deficit.

Aged↗
PubMed2004

Physical activity, self-efficacy, and perceived exertion among adolescents.

The relationship of self-efficacy, a sense of confidence in personal physical activity (PA) skills, to perceived exertion during activity was explored among 168 African American and European American boys and girls between 9 and 17 years of age. Participants walked/ran on a treadmill at a speed equivalent to 60% of their peak VO2 for 20 minutes and provided ratings of exertion every 4 minutes. Pre-activity self-efficacy predicted perceived exertion for boys only. Girls were lower than boys in pre-activity self-efficacy and subsequently reported greater perceived exertion. For both genders, lower perceived exertion during PA resulted in higher post-activity self-efficacy. Uncomfortable perceptions of exertion during initial efforts to increase PA are likely to discourage future activity. Interventions that can lower perceptions of exertion may enhance self-efficacy and promote a sense of competence in PA skills.

Adolescent↗
PubMed2003

The effect of passive heating and face cooling on perceived exertion during exercise in the heat.

Increased body temperature is thought to be an important component of the higher perception of exertion that is a feature of fatigue during exercise in the heat but a causal relationship has yet to be demonstrated. We have investigated the effect of passive heating on the perception of exertion during a standard bout of exercise and also assessed the effect of cooling the head on compensating for the increased body temperature on the feelings of exertion. Ten male subjects performed a 14-min cycling exercise [average power approximately 63% of maximum power output ( W(max))] at an ambient temperature of 35 degrees C at resting rectal temperature [mean (SD): 37.49 (0.27) degrees C; control (CON) trial] on one occasion, and after sitting in a sauna to raise rectal temperature [mean (SD): 38.95(0.13) degrees C; sauna (SAU) trial]. During the exercise, subjects reported their ratings of overall perceived exertion (RPE), perceived exertion of the legs (RPE(legs)) and thermal comfort (TC). A blood sample was collected by the end of the exercise for determination of plasma glucose, lactate and prolactin and haematocrit. RPE values were significantly elevated after passive heating [mean (SE): 14.5 (0.7) units in CON and 17.2 (0.5) units in SAU, at the end of exercise; P<0.001] as were the RPE(legs) ( P<0.01), while ratings of TC were similar in CON and SAU trials. Passive heating increased blood glucose ( P<0.05) but had no effect on lactate at the end of the exercise. Plasma prolactin was markedly elevated as a result of the sauna exposure [mean (SE): 1598 (152) versus 225 (31) mU l(-1) in SAU and CON trials, respectively; P<0.001]. Six of the subjects repeated the two trials but with the face cooled during exercise (trials CON(FAN) and SAU(FAN)) that was achieved by combining face fanning and spraying the face with a mist of cooled water. Face cooling decreased RPE values after sauna to a point that no differences between the two conditions existed. RPE(legs) scores and heart rate, however, remained higher in SAU(FAN) compared with CON(FAN) ( P<0.05). We conclude that hyperthermia is a causative element of the increased perception of exertion during submaximal exercise in the heat and that the effect of increased core temperature on the feelings of exertion is modulated by face cooling.

Adult↗