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Biomedical subjects

M A Kolka

Publications and source records attributed to M A Kolka.

At least 19 recordsLinked to original sources
PubMed2001

Physiologic tolerance to uncompensable heat: intermittent exercise, field vs laboratory.

PURPOSE: This study determined whether exercise (30 min)-rest (10 min) cycles alter physiologic tolerance to uncompensable heat stress (UCHS) when outdoors in the desert. In addition, the relationship between core temperature and exhaustion from heat strain previously established in laboratory studies was compared with field studies. METHODS: Twelve men completed four trials: moderate intensity continuous exercise (MC), moderate intensity exercise with intermittent rest (MI), hard intensity continuous exercise (HC), and hard intensity exercise with intermittent rest (HI). UCHS was achieved by wearing protective clothing and exercising (estimated at 420 W or 610 W) outdoors in desert heat. RESULTS: Heat Stress Index values were 200%, 181%, 417%, and 283% for MC, MI, HC, and HI, respectively. Exhaustion from heat strain occurred in 36 of 48 trials. Core temperatures at exhaustion averaged 38.6 +/- 0.5 degrees, 38.9 +/- 0.6 degrees, 38.9 +/- 0.7 degrees, and 39.0 +/- 0.7 degrees C for MC, MI, HC, and HI, respectively. Core temperature at exhaustion was not altered (P > 0.05) by exercise intensity or exercise-rest cycles and 50% of subjects incurred exhaustion at core temperature of 39.4 degrees C. These field data were compared with laboratory and field data collected over the past 35 years. Aggregate data for 747 laboratory and 131 field trials indicated that 50% of subjects incurred exhaustion at core temperatures of 38.6 degrees and 39.5 degrees C, respectively. When heat intolerant subjects (exhaustion < 38.3 degrees C core temperature) were removed from the analysis, subjects from laboratory studies (who underwent short-term acclimation) still demonstrated less (0.8 degrees C) physiological tolerance than those from field studies (who underwent long-term acclimatization). CONCLUSION: Exercise-rest cycles did not alter physiologic tolerance to UCHS. In addition, subjects from field studies demonstrate greater physiologic tolerance than subjects from laboratory studies.

Adaptation, Physiological↗
PubMed2001

Heat strain imposed by toxic agent protective systems.

This study evaluated physiological heat strain from two developmental toxic agent protective systems compared with the standard Toxicological Agent Protective (TAP) suit during exercise-heat stress. Eight subjects (six men, two women) completed three experimental trials, at 38 degrees C, 30% rh, wearing: 1) Self Contained Toxic Environment Protective Outfit (STEPO) with rebreather (STEPO-R); 2) STEPO with tether (STEPO-T) or 3) the standard TAP. The STEPO systems provided effective body cooling of: STEPO-R, 200 +/- 36 W; and STEPO-T, 186 +/- 59 W. TAP had no cooling. All experimental trials used treadmill walking at 0.89 m x s(-1), 0% grade at exercise/rest cycles of 20/10 min for 240 min. Metabolic rates for the treatments were: STEPO-R, 298 +/- 26 W; STEPO-T, 299 +/- 34 W; and TAP, 222 +/- 40 W. Rate of heat storage was less (p < 0.05) in STEPO-R (37 +/- 8 W x m(-2)) and STEPO-T (38 +/- 12 W x m(-2)) than in TAP (77 +/- 15 W x m(-2)). Sweating rate was less (p < 0.05) in STEPO-T (10.0 +/- 4.8 g x min(-1)) than in TAP (23.8 x 11.4 g x min(-1)). There was no difference between STEPO-R (12.3 +/- 5.6 g min(-1)) and the other two uniform systems. Subjects did not complete targeted exposure times of 240 min. Exposure time was longer (p < 0.05) in STEPO-R (83 +/- 22 min) and STEPO-T (106 +/- 39 min) than in TAP (46 +/- 10 min). Predicted time to 39.0 degrees C was less (p < 0.05) in TAP (69 +/- 20 min) than in either STEPO-R (226 +/- 124 min) or STEPO-T (244 +/- 170 min). The results of this study show that cooling in STEPO significantly reduced heat storage relative to TAP. The new generation toxic cleanup uniform systems effectively reduced heat stress and increased work capabilities compared with the standard TAP suit.

Adult↗
PubMed2001

Heat strain evaluation of chemical protective garments.

BACKGROUND: The purpose of this study was to compare thermoregulatory and subjective responses of 12 test subjects (10 male, 2 female) wearing 5 different Joint Service Lightweight Integrated Suit Technology (JSLIST) prototype and 3 different currently fielded control chemical/ biological (CB) protective overgarments. METHODS: The overgarments were compared while subjects attempted to complete 100 min of moderate exercise (400 W) in an environmental chamber (35 degrees C/50% rh). Rectal temperature (Tre), skin temperature, heart rate, sweating rate, and test time, as well as subjective symptoms of heat illness were measured. Data were analyzed for times earlier than 100 min because subjects were not usually able to complete the 100-min trials. RESULTS: At 50 min, of the 3 controls, the Army/Air Force Battledress Overgarment (BDO) imposed significantly greater heat strain (indicated by Tre 37.90 degrees C) than the Marine Saratoga (SAR) (Tre 37.68 degrees C) and Navy Chemical Protective Overgarment (CPO) (Tre 37.69 degrees C). The JSLIST prototype garments imposed heat strain (50 min Tre 37.73-37.86 degrees C) as well as subjective perception of heat strain, that ranged between the warmest and coolest controls. CONCLUSIONS: In the environmental and exercise test conditions of this study, we did not find the five JSLIST overgarments to be consistently different from one another. Subjects in the control garments were and felt generally warmer (BDO) or cooler (SAR, CPO) than in the JSLIST prototype garments.

Adult↗
PubMed2000

Circadian rhythm changes in core temperature over the menstrual cycle: method for noninvasive monitoring.

The purpose of this study was to determine whether core temperature (T(c)) telemetry could be used in ambulatory women to track changes in the circadian T(c) rhythm during different phases of the menstrual cycle and, more specifically, to detect impending ovulation. T(c) was measured in four women who ingested a series of disposable temperature sensors. Data were collected each minute for 2-7 days and analyzed in 36-h segments by automated cosinor analysis to determine the mesor (mean temperature), amplitude, period, acrophase (time of peak temperature), and predicted circadian minimum core temperature (T(c-min)) for each cycle. The T(c) mesor was higher (P < or = 0.001) in the luteal (L) phase (37.39 +/-0.13 degrees C) and lower in the preovulatory (P) phase (36.91 +/-0.11 degrees C) compared with the follicular (F) phase (37.08 +/-0.13 degrees C). The predicted T(c-min) was also greater in L (37.06 +/- 0.14 degrees C) than in menses (M; 36.69 +/- 0.13 degrees C), F (36. 6 +/- 0.16 degrees C), and P (36.38 +/- 0.08 degrees C) (P < or = 0. 0001). During P, the predicted T(c-min) was significantly decreased compared with M and F (P < or = 0.0001). The amplitude of the T(c) rhythm was significantly reduced in L compared with all other phases (P < or = 0.005). Neither the period nor acrophase was affected by menstrual cycle phase in ambulatory subjects. The use of an ingestible temperature sensor in conjunction with fast and accurate cosinor analysis provides a noninvasive method to mark menstrual phases, including the critical preovulatory period.

Adult↗
PubMed1999

Esophageal temperature threshold for sweating decreases before ovulation in premenopausal women.

The purpose of this study was to test the hypothesis that regulated body temperature is decreased in the preovulatory phase in eumenorrheic women. Six women were studied in both the preovulatory phase (Preov-2; days 9-12), which was 1-2 days before predicted ovulation when 17beta-estradiol (E2) was estimated to peak, and in the follicular phase (F; days 2-6). The subjects walked on a treadmill ( approximately 225 W x m-2) in a warm chamber (ambient temperature = 30 degreesC; dew-point temperature = 11.5 degreesC) while heavily clothed. E2, esophageal temperature (Tes), local skin temperatures, and local sweating rate were measured. The estimate of when the E2 surge would occur was correct for four of six subjects. In these four subjects, E2 increased (P </= 0.05) from 42.0 +/- 24.5 pg/ml during F to 123.2 +/- 31.3 pg/ml during Preov-2. Resting Tes was 37.02 +/- 0.20 degreesC during F and 36.76 +/- 0.28 degreesC during Preov-2 (P </= 0.05). The Tes threshold for sweating was decreased (P </= 0.05) from 36.88 +/- 0.27 degreesC during F to 36. 64 +/- 0.35 degreesC during Preov-2. Both mean skin and mean body temperatures were decreased during rest in Preov-2 group. The hypothesis that regulated body temperature is decreased during the preovulatory phase is supported.

Adult↗
PubMed1999

A persistent circhoral ultradian rhythm is identified in human core temperature.

There have been inconclusive reports of intermittent rhythmic fluctuations in human core temperature, with the fluctuations having a period of about an hour. However, there has been no definitive demonstration of the phenomenon. This is likely due to the intermittency and seeming instability of the events. They have been assumed to be secondary rather than autonomous phenomena, putatively arising from the oscillation between rapid eye movement (REM) and non-REM (NREM) sleep. In this study, we report identification of a clear, persistent circhoral ultradian rhythm in core temperature with a period for this study sample of 64 +/- 8 minutes. It appeared simultaneously with an intact circadian core temperature rhythm, persisted despite complex perturbations in core temperature brought about by the sequelae of 40 h of sleep deprivation, and could not be attributed to sleep stage alternation or other endogenous or exogenous factors. Analysis of power spectra using the maximum entropy spectral analysis (MESA) method, which can uncover hidden rhythmicities, demonstrated that the apparent intermittency of the rhythm is due to periodic interference of this rhythm by other rhythmic events. The persistence of this oscillation suggests that, in this system as in the endocrine system, circhoral regulation is an integral component of thermoregulatory control. Identifying the source and functional role of this novel rhythm warrants further work.

Activity Cycles↗
PubMed1999

Cross validation of USARIEM heat strain prediction models. U.S. ARMY Research Institute of Environmental Medicine.

HYPOTHESIS: This study was a cross validation of three heat strain prediction models developed at the U.S. Army Research Institute of Environmental Medicine: the ARIEM, HSDA, and ARIEM-EXP models ability to predict core temperature. METHODS: Seven heat-acclimated subjects completed twelve experimental tests, six in each of two hot climates, at three exercise intensities and two uniform configurations in each climate. RESULTS: Experimental results showed physiological responses as expected with heat strain increasing with work load and level of protective clothing, but with similar heat strain between the two environments matched for wet bulb, globe index. Neither the ARIEM or HSDA model closely predicted core temperatures over the course of the experiment, due mostly to an abrupt initial rise in core temperature in both models. A proportionality constant in the ARIEM-EXP buffered some of this abrupt rise. CONCLUSIONS: Comparisons of the core temperature and tolerance times data with the three models led to the conclusions that for healthy males: 1) the ARIEM and HSDA models provide conservative safety limits as a result of predicting rapid initial increases in core temperature; 2) the ARIEM-EXP most closely represents core temperature responses; 3) the ARIEM-EXP requires modifications with an alternate proportionality coefficient to increase accuracy for low metabolic cost exercise; 4) all of the models require additional input from existing research on tolerance to heat strain to better predict tolerance times; and 5) additional models should be examined to investigate the transient state of the body as it is affected by environment, clothing and exercise.

Acclimatization↗
PubMed1997

Effect of luteal phase elevation in core temperature on forearm blood flow during exercise.

Forearm blood flow (FBF) as an index of skin blood flow in the forearm was measured in five healthy women by venous occlusion plethysmography during leg exercise at 80% peak aerobic power and ambient temperature of 35 degrees C (relative humidity 22%; dew-point temperature 10 degrees C). Resting esophageal temperature (T(es)) was 0.3 +/- 0.1 degrees C higher in the midluteal than in the early follicular phase of the menstrual cycle (P < 0.05). Resting FBF was not different between menstrual cycle phases. The T(es) threshold for onset of skin vasodilation was higher (37.4 +/- 0.2 degrees C) in midluteal than in early follicular phase (37.0 +/- 0.1 degrees C; P < 0.05). The slope of the FBF to T(es) relationship was not different between menstrual cycle phases (14.0 +/- 4.2 ml x 100 ml(-1) x min(-1) x degrees C(-1) for early follicular and 16.3 +/- 3.2 ml x 100 ml(-1) x min(-1) x degrees C(-1) for midluteal phase). Plateau FBF was higher during exercise in midluteal (14.6 +/- 2.2 ml x 100 ml(-1) x min(-1) x degrees C(-1)) compared with early follicular phase (10.9 +/- 2.4 ml x 100 ml(-1) x min(-1) x degrees C(-1); P < 0.05). The attenuation of the increase in FBF to T(es) occurred when T(es) was 0.6 degrees C higher and at higher FBF in midluteal than in early follicular experiments (P < 0.05). In summary, the FBF response is different during exercise in the two menstrual cycle phases studied. After the attenuation of the increase in FBF and while T(es) was still increasing, the greater FBF in the midluteal phase may have been due to the effects of increased endogenous reproductive endocrines on the cutaneous vasculature.

Adult↗
PubMed1997

Effects of topical skin protectant on heat exchange in humans.

BACKGROUND: The application of a Topical Skin Protectant (TSP) under chemical protective clothing may impair heat exchange and/or decrease tolerance time during exercise. HYPOTHESIS: The extent to which TSP might act as a barrier to heat transfer was unknown. Since TSP may be permeable to water vapor, we hypothesized that there would be no significant differences between treatments on variables effecting heat exchange. METHODS: There were 10 subjects who walked (3.5 mph, 3% grade) until volitional exhaustion in an environmental chamber (TA = 36.0 +/- 0.5 degrees C; TDP = 27.0 +/- 1.0 degrees C) in two conditions: no TSP application (CON) and TSP application (TSP). TSP was applied to 21% of body surface area on six specific areas. Esophageal temperature, skin temperature (8 sites), heart rate, and pre- and post-experimental weights were measured. Mean skin temperature, mean body temperature, changes in esophageal temperature per min of exercise, evaporative heat loss, and sweating rate were calculated. RESULTS: There was no effect (p < 0.05) of TSP on esophageal temperature, mean skin temperature, heart rate, tolerance time (CON: 139.3 +/- 32.5 vs. TSP: 132.3 +/- 37.0 min), sweating rate (CON: 9.5 +/- 1.9 vs. TSP: 9.4 +/- 3.03 g.min-1) and evaporative heat loss (CON: 200.9 +/- 31.6 vs. TSP: 215.9 +/- 25.9 W.m-2). The change in TES per min of exercise averaged 0.014 +/- 0.003 degree C during TSP and 0.012 +/- 0.003 degree C during CON, and was higher (p = 0.024) in TSP. At this rate, the difference between treatments for 4 h would be 0.48 degree C. There were no adverse local or systemic reactions to TSP application. CONCLUSIONS: TSP application minimally affected heat exchange under the conditions of this study.

Administration, Cutaneous↗
PubMed1993

Seven-day pyridostigmine administration and thermoregulation during rest and exercise in dry heat.

Seven men participated in a double-blind study of effects of multiple-dose oral pyridostigmine bromide (PB) on physiological responses to 4-h heat stress tests (HST's) in a hot dry environment, 42 degrees C, 20% relative humidity. Subjects underwent 2 7-d series of tests, separated by 72 h, taking 30 mg PB every 8 h in one series, and placebo in the other. Each HST began right after the 0800 dose of PB or placebo. Subjects drank ad libitum during each HST, and performed two 55-min treadmill walks at about 40% VO2max during the last 2 h. Inhibition of red cell cholinesterase at the start of exercise averaged 30.0% in subjects taking PB, and did not differ significantly among HST's with PB. PB increased sweating and evaporative water loss by about 4%, and lowered chest skin temperature during exercise by 0.7 degrees C; but it had no significant effect on rectal temperature, other skin temperatures, O2 uptake, or fluid balance. PB alone had no significant effect on heart rate (HR), but had a significant interaction with day: although PB had essentially no effect on HR in the 1st HST, its effect increased progressively so that HR during exercise in the 4th HST was 8 beats.min-1 lower with PB. Multiple-dose PB had only slight effects on responses to moderate exercise-heat stress beyond those described after single-dose PB, and we found no adverse effects of multiple-dose PB administration.

Administration, Oral↗
PubMed1992

Chronic pyridostigmine bromide administration: side effects among soldiers working in a desert environment.

The side effects of chronic pyridostigmine bromide administration were studied in seven male soldiers performing moderate-intensity exercise in a desert environment. A 2-week, double-blind, placebo-controlled crossover design was employed in which pyridostigmine was administered for 7 consecutive days (30 mg orally, t.i.d.). Four hours each day were spent in the heat (42 degrees C, 20% relative humidity); 2 hours rest followed by 2 hours moderate exercise (40% maximal aerobic power). Each day, subjects completed four symptom questionnaires and received three focused physical examinations. Symptoms reported did not differ between treatment groups except for fewer headaches during pyridostigmine treatment. Soldiers were unable to distinguish the effects of pyridostigmine from placebo. Pyridostigmine was associated with lower resting diastolic blood pressure (approximately 4 mmHg, p less than 0.05), smaller pupil diameter (approximately 0.5 mm, p less than 0.01), decreased handgrip strength (approximately 3%, p less than 0.05), and higher final rectal temperature (approximately 0.1 degree C, p less than 0.01). Effects of this magnitude are not likely to appreciably limit performance. We conclude that chronic pyridostigmine administration does not negatively impact on soldiers' ability to perform physical work over repeated days in a desert environment.

Adolescent↗
PubMed1990

Acetylcholinesterase inhibitor, pyridostigmine bromide, reduces skin blood flow in humans.

Five subjects exercised on a cycle ergometer for 30 min at 55% peak oxygen consumption on two occasions in an environmental test chamber (ambient temperature = 29 degrees C; dew point temperature = 10 degrees C). Pyridostigmine bromide (PYR), an acetylcholinesterase (AChE) inhibitor, was ingested (30 mg) approximately 150 min before one experiment, and no drug was administered during the other experiment (control). Red blood cell AChE inhibition averaged 40 (+/- 7)% during PYR treatment. Esophageal temperature (Tes), an eight site-derived mean skin temperature, forearm blood flow (FBF; venous occlusion plethysmography), skin blood flow (SkBF; laser-Doppler velocimetry), and metabolic rate (indirect calorimetry) were measured. SkBF decreased 37% after PYR treatment compared with control (P less than or equal to 0.05). The Tes threshold for initiation of cutaneous vasodilation was 36.8 (+/- 0.3) degrees C for the control treatment and 37.0 (+/- 0.3) degrees C for the PYR treatment (P less than or equal to 0.01). FBF was not significantly different between treatments, whereas heart rate was reduced by 7 and 9 beats/min during rest and exercise, respectively (P less than or equal to 0.01). The increased threshold for initiation of cutaneous vasodilation with AChE inhibition by PYR is compatible with nonthermal modulation of the control of thermoregulation through increased acetylcholine (ACh) accumulation. This could potentiate preganglionic transmission to enhance adrenergic vasoconstrictor tone. One suggested mechanism possible at the neuroeffector junction of the sweat gland may be that accumulated ACh diffusion across the adventitia of adjacent arterioles to muscarinic receptors initiates contraction of the smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Heat exchange after cholinolytic and oxime therapy in protective clothing.

The effect of the currently fielded therapeutic antidotal (DRUG) combination (a cholinolytic, 2 mg of atropine sulfate, and an oxime, 600 mg of pralidoxime chloride) in combination with chemical protective Mission Oriented Protective Posture clothing (MOPP IV) was studied. Eight healthy male subjects participated in intermittent light physical activity (1.4-2.1 kcal/minute) in two distinct environments: 35 degrees C, 60% rh (95 degrees F, HOT) and 13 degrees C, 44% rh (55 degrees F, COOL). Subjects were exposed once to HOT wearing MOPP (CON) and once wearing MOPP after DRUG. Similarly, each subject was exposed to COOL wearing MOPP and MOPP after DRUG. Rectal temperature (Tre) and mean weighted skin temperature (Tsk) were not different between DRUG and CON during COOL. Exposure time during COOL was 350 minutes. Tre averaged .5 degrees C higher in DRUG than CON in HOT. The rate of core temperature increase was 2 times faster in DRUG than CON in HOT. Tsk was 1.0 degrees C higher in DRUG experiments in HOT. Whole-body sweating rate was 40% lower (p less than .05) in DRUG than CON experiments in HOT. Heart rate was 27 beats/minute higher by 30 minutes post-injection in DRUG at 35 degrees C. Exposure time was 213 +/- 30 minutes in CON and 190 +/- 38 minutes in DRUG at 35 degrees C. These data indicate the currently fielded therapeutic antidotal drug combination increases thermal strain in subjects exposed to a hot environment when wearing protective clothing. The results are applicable to subjects performing light, intermittent work. At higher work intensities, these findings of increased thermal strain would be exacerbated.

Adult↗
PubMed1990

Human temperature regulation during exercise after oral pyridostigmine administration.

Four healthy males exercised in two experiments at ambient temperatures of 22, 29, and 36 degrees C with the relative humidity at 30% in all environments (Tdp = 3.9, 9.9, and 15.8 degrees C). One experiment in each environment was done 150 min after 30 mg oral pyridostigmine bromide (PYR) administration, and the second experiment was done on a separate day with no medication (CON). Red blood cell cholinesterase was 39 +/- 7% lower after PYR (11.8 vs 7.2 micromol.ml-1.min-1). Esophageal (Tes) and mean skin temperature (Tsk), forearm blood flow (FBF), forearm sweating, and skin blood flow (SkBF) were measured twice each minute during a 15-min rest period and during 30-min of seated cycle exercise at approximately 58% Vo2peak. Whole body sweating was determined from weight changes before and after exercise. PYR decreased heart rate at rest and during exercise at 29 degrees C and 36 degrees C (8bpm, p less than 0.05). Resting SkBF was 40% lower at 29 degrees C and 30% lower at 36 degrees C after PYR compared to CON (p less than 0.05). There was no effect of PYR on heat production at rest or during exercise. Tsk was different in the three conditions by design, but was unchanged by PYR. Tes was not different at rest in any condition, but was elevated during exercise at 36 degrees C (0.1 degree C, p less than 0.05) in PYR compared to CON. These data suggest that pyridostigmine ingestion decreased skin blood flow, which may limit exercise thermoregulation in more severe environments.

Administration, Oral↗
PubMed1989

Circadian variations in plasma renin activity, catecholamines and aldosterone during exercise in women.

Four women were studied at 0400 h and 1600 h to determine if their hormonal and hemodynamic responses to exercise varied with the circadian cycle. Esophageal temperature was measured during rest and exercise (60% peak VO2; 30 min) in a warm room (Ta = 35 degrees C; PH2O = 1.7 kPa). Venous blood samples were drawn during rest and exercise and hemoglobin concentration (Hb), hematocrit (Hct), plasma osmolality (Posm), plasma protein concentration (Pp), colloid osmotic pressure (COP), plasma renin activity (PRA), cortisol, aldosterone, norepinephrine (NE) and epinephrine (E) were determined. Changes in plasma volume (PV) were estimated from changes in Hb and Hct. The relative hemoconcentration (-11.2%) was similar at 0400 h and 1600 h, but the absolute PV was smaller at 1600 h than at 0400 h (p = 0.03). The responses of Posm, Pp and COP to exercise were unaffected by time of day. Although PRA was not different at the two times of day, PRA was 244% greater during exercise at 1600 h, but only 103% greater during exercise at 0400 h. The normal circadian rhythms in plasma aldosterone (p = 0.043) and plasma cortisol (p = 0.004) were observed. Plasma aldosterone was 57% greater during exercise, while plasma cortisol did not change. The change in E and NE was greater at 0400 h, but this was due to the lower resting values of the catecholamines at 0400 h. These data indicate that time of day generally did not affect the hormonal or hemodynamic responses to exercise, with the exception that PRA was markedly higher during exercise at 1600 h compared to 0400 h.

Adult↗
PubMed1989

Control of sweating during the human menstrual cycle.

Thermoregulatory responses were studied in seven women during two separate experimental protocols in the follicular (F, days 4-7) phase and during the luteal (L, days 19-22) phase of the menstrual cycle. Continuous measurements of esophageal temperature (Tes), mean skin temperature (Tsk), oxygen uptake and forearm sweating (ms) were made during all experiments. Protocol I involved both passive heat exposure (3 h) and cycle exercise at approximately 80% VO2 peak during which the environmental chamber was controlled at Ta = 50.0 degrees C, rh = 14% (Pw = 1.7 kPa). In protocol II subjects were tested during thirty-five minutes of exercise at approximately 85% VO2 peak at Ta = 35 degrees C and rh = 25% (Pw = 1.4 kPa). The normal L increase in resting Tes (approximately 0.3 degrees C) occurred in all seven subjects. Tsk was higher during L than F in all experiments conducted at 50 degrees C. During exercise and passive heat exposure, the Tes threshold for sweating was higher in L, with no change in the thermosensitivity (slope) of ms to Tes between menstrual cycle phases. This rightward or upward shift in Tes threshold for initiation of sweating averaged 0.5 degrees C for all experiments. The data indicate the luteal phase modulation in the control of sweating in healthy women is also apparent during severe exercise and/or heat stress.

Adult↗