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PubMed2003

The effects of the level of alertness during the rest period on subsequent performance.

The aim of this study was to examine how to take an effective rest to prevent a decline in alertness at work. The relationship between alertness during the rest period and subsequent task performance were investigated. The electroencephalogram (EEG) during the rest period was classified into 3 types, and these types had a significant effect on performance after the rest period. Type 1 (increasing in theta, alpha 2, and beta 1 power) was the best one for carrying out the task, whereas performance gradually declined in Type 3 (no change in EEG activity). In the case of Type 1, the method that would relieve sleep inertia had a more positive impact on performance after the rest period.

Adult↗
PubMed1987

Tracheal and bronchoalveolar permeability changes in rats inhaling oxidant atmospheres during rest or exercise.

Permeability of tracheal and bronchoalveolar airways of rats was measured and used to examine the effects of inhaled oxidant-containing atmospheres. The atmospheres studied were (a) ozone (O3) at 0.6 ppm (1.2 mg/m3) or 0.8 ppm (1.6 mg/m3); (b) nitrogen dioxide (NO2) at 6 ppm (11.3 mg/m3) or 12 ppm (22.6 mg/m3); (c) O3 + NO2 at 0.6 ppm (1.2 mg/m3) and 2.5 ppm (4.7 mg/m3), respectively; and (d) a 7-component particle and gas mixture (complex atmosphere) representing urban air pollution in a photochemical environment. The rats were exposed for 2 h. The effects of exercise during exposure were evaluated by exposing additional groups in an enclosed treadmill. Exposure of resting rats to 0.8 ppm O3 increased tracheal permeability to DTPA and bronchoalveolar permeability to diethylenetriamine pentaacetate (DTPA) and bovine serum albumin (BSA) at 1 h after the exposure. Bronchoalveolar, but not tracheal, permeability remained elevated at 24 h after the exposure. Exercise during exposure to O3 increased permeability to both tracers in the tracheal and the bronchoalveolar zones, and prolonged the duration of increased permeability in the tracheal zone from 1 h to 24 h, and in the bronchoalveolar zone from 24 h to 48 h. Permeability in the tracheal and bronchoalveolar zones of rats exposed at rest to 6 or 12 ppm NO2 did not differ from controls. However, rats exposed during exercise to 12 ppm NO2 for 2 h developed a significant increase in tracheal and bronchoalveolar permeability to DTPA and BSA at 1 h, but not at 24 or 48 h, after exposure. Exposure at rest to 0.6 ppm O3 plus 2.5 ppm NO2 significantly increased bronchoalveolar permeability at 1 and 24 h after exposure, although exposure at rest to 0.6 ppm O3 alone increased bronchoalveolar permeability only at 1 h after exposure. Exposure to O3 + NO2 during exercise led to significantly greater permeability to DTPA than did exercising exposure to O3 alone. Resting rats exposed to a complex gas/aerosol atmosphere composed of the above O3 and NO2 concentrations, plus 5 ppm (13.1 mg/m3) sulfur dioxide (SO2) and an aerosol of insoluble colloidal Fe2O3 with an aerosol of manganese, ferric, and ammonium salts, demonstrated increased permeability at 1 and 24 h after exposure. Nitric acid vapor was formed in both the O3 + NO2 atmosphere and the complex gas/aerosol atmosphere.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Inhalation↗
PubMed2000

Circadian rhythms in human muscular efficiency: continuous physical exercise versus continuous rest. A crossover study.

This study deals with the influence of time of day on neuromuscular efficiency in competitive cyclists during continuous exercise versus continuous rest. Knee extension torque was measured in ultradistance cyclists over a 24h period (13:00 to 13:00 the next day) in the laboratory. The subjects were requested to maintain a constant speed (set at 70% of their maximal aerobic speed obtained during a preliminary test) on their own bicycles, which were equipped with cyclosimulators. Every 4h, torque developed and myoelectric activity were estimated during maximal isometric voluntary contractions of knee extensors using an isokinetic dynamometer. Mesenteric temperature was monitored by telemetry. The same measures were also recorded while the subjects were resting awake until 13:00 the next day. During activity, torque changed within the 24h period (p < .005), with an acrophase at 19:10 and an amplitude of 7.8% around the mean of 70.7%. At rest, a circadian rhythm was observed in knee extensor torque (p < .05), with an acrophase at 19:30 and an amplitude of 6% around the mean of 92.3%. Despite the standardized conditions, the results showed that isometric maximal strength varied with time of day during both a submaximal exercise and at rest without prior exercise. The sine waves representing these two rhythms were correlated significantly. Although at rest the diurnal rhythm followed muscular activity (i.e., neurophysiological factors), during exercise, this rhythm was thought to stem more from fluctuations in the contractile state of muscle.

Adult↗
PubMed2006

Rapid dual-injection single-scan 13N-ammonia PET for quantification of rest and stress myocardial blood flows.

Quantification of myocardial blood flows at rest and stress using 13N-ammonia PET is an established method; however, current techniques require a waiting period of about 1 h between scans. The objective of this study was to test a rapid dual-injection single-scan approach, where 13N-ammonia injections are administered 10 min apart during rest and adenosine stress. Dynamic PET data were acquired in six human subjects using imaging protocols that provided separate single-injection scans as gold standards. Rest and stress data were combined to emulate rapid dual-injection data so that the underlying activity from each injection was known exactly. Regional blood flow estimates were computed from the dual-injection data using two methods: background subtraction and combined modelling. The rapid dual-injection approach provided blood flow estimates very similar to the conventional single-injection standards. Rest blood flow estimates were affected very little by the dual-injection approach, and stress estimates correlated strongly with separate single-injection values (r=0.998, mean absolute difference=0.06 ml min-1 g-1). An actual rapid dual-injection scan was successfully acquired in one subject and further demonstrates feasibility of the method. This study with a limited dataset demonstrates that blood flow quantification can be obtained in only 20 min by the rapid dual-injection approach with accuracy similar to that of conventional separate rest and stress scans. The rapid dual-injection approach merits further development and additional evaluation for potential clinical use.

Ammonia↗
PubMed2005

Evaluation of potentially significant increase of lead in the blood during long-term bed rest and space flight.

We address a gap in the knowledge of lead turnover under conditions of prolonged bed rest and microgravity by developing a quantitative model of the amount of lead returned to blood circulation from bone. We offer the hypothesis that skeletal unloading, such as typically occurs during extended bed rest or microgravity, will result in bone lead being released to the blood, as has already been demonstrated in the case of calcium. We use initial bone lead concentrations to develop predictive models of blood lead elevation. Our theoretical calculations with typical bone lead loads measured in today's 40-60-year-old generation, suggest that the estimated blood lead concentrations in long duration (e.g., 100 days) space flight could average between 20 and 40 microg dl(-1), a range with well-established toxic effects. For a similar duration of bed rest, estimated blood lead concentration could be as high as 10-20 microg dl(-1), which is a level of concern, particularly if we consider females of childbearing age. The preliminary experimental results were obtained under multi-institutional collaborations, with the main outcome received from an on-going bed rest study, Prevention of Microgravity-Induced Stone Risk by KMgCitrate, conducted at the General Clinical Research Center (GCRC) of the University of Texas Southwestern Medical Center, Dallas. Based on theoretical modeling and some preliminary experimental results, this concept may have important clinical implications by allowing prediction of the magnitude of blood lead elevation, thereby establishing the means to prevent lead toxicity during long duration space flight of astronauts and in conditions of prolonged bed rest such as complicated pregnancy, spinal cord injury induced paralysis and comatose patients.

Bed Rest↗
PubMed1988

Zinc, copper, and nitrogen balances during bed rest and fluoride supplementation in healthy adult males.

The effects of bed rest and fluoride supplementation on zinc, copper, and nitrogen balances and Zn and Cu serum levels were measured in 15 healthy males. Subjects aged 19-54 y remained on a metabolic research ward for 10 wk. During weeks 1-5, subjects were ambulatory. During wks 6-10 they remained in continuous bed rest. During weeks 3-10 nine subjects received 10 or 20 mg F/d as sodium fluoride. Daily urine and weekly fecal composites were made and biweekly fasting blood samples were taken. Dietary intakes were 1.40 +/- 0.17 mg Cu/d (22.0 +/- 2.7 mumol Cu/d), 10.82 +/- 0.49 mg Zn/d (165.6 +/- 7.6 mumol Zn/d), and 14.27 +/- 0.23 g N/d (1019 +/- 16 mmol N/d). Bed rest increased urinary Zn and N excretions and fecal Zn excretions and decreased Zn balance (p less than 0.05) whereas Cu balance was unchanged. During bed rest, F supplementation increased Zn and N balances compared with untreated control subjects (p less than 0.05). These results are compatible with bone and muscle atrophy during bed rest and increased bone formation with F supplementation.

Adult↗
PubMed2000

Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine.

BACKGROUND: The effects of food restriction on energy metabolism have been under investigation for more than a century. Data obtained are conflicting and research has failed to provide conclusive results. OBJECTIVE: The objective of this study was to test the hypothesis that in lean subjects under normal living conditions, short-term starvation leads to an increase in serum concentrations of catecholamines and thus to an increase in resting energy expenditure. DESIGN: Resting energy expenditure, measured by indirect calorimetry, and hormone and substrate concentrations were measured in 11 healthy, lean subjects on days 1, 2, 3, and 4 of an 84-h starvation period. RESULTS: Resting energy expenditure increased significantly from 3.97 +/- 0.9 kJ/min on day 1 to 4.53 +/- 0.9 kJ/min on day 3 (P < 0.05). The increase in resting energy expenditure was associated with an increase in the norepinephrine concentration from 1716. +/- 574 pmol/L on day 1 to 3728 +/- 1636 pmol/L on day 4 (P < 0.05). Serum glucose decreased from 4.9 +/- 0.5 to 3.5 +/- 0.5 mmol/L (P < 0.05), whereas insulin did not change significantly. CONCLUSIONS: Resting energy expenditure increases in early starvation, accompanied by an increase in plasma norepinephrine. This increase in norepinephrine seems to be due to a decline in serum glucose and may be the initial signal for metabolic changes in early starvation.

3-Hydroxybutyric Acid↗
PubMed1993

Elevated resting heart rate in rheumatoid arthritis: possible role of physical deconditioning.

Thirty-four patients with RA, 76 diabetic subjects (DM) and 67 healthy controls (CR) were studied in order to study cardiovascular autonomic function in RA. Valsalva manoeuvre, deep breathing test and active orthostatic test were used. Resting heart rate (resting HR) was markedly elevated in the RA and DM groups. Therefore, the groups were compared using analysis of variance with age and resting HR as covariates. The analyses showed no differences in cardiovascular responses between the RA group and CR group but cardiovascular responses were significantly diminished in the DM group compared with both the CR group and RA group. Our data indicate that the parasympathetic efferent pathway mediating cardiovascular reflexes via the nervus vagus is intact in RA. Thus elevated resting HR in RA does not seem to be due to peripheral parasympathetic damage. Physical deconditioning may explain the elevation of resting HR in patients with RA.

Adult↗
PubMed2001

Increased central body fat deposition precedes a significant rise in resting blood pressure in male offspring of essential hypertensive parents: a 5 year follow-up study.

OBJECTIVES: As long as offspring of essential hypertensive parents (OHyp) are lean, their blood pressure usually remains within normal limits. The mechanism(s) transforming this 'genetically dysregulated normotension' into hypertension are unclear. We hypothesized that OHyp are not only genetically prone to develop hypertension, but may also have a particular propensity to accumulate central body fat. DESIGN: A 5-year follow-up cohort study. SETTING: University Hospital in Switzerland. PARTICIPANTS: Seventeen young (25 +/- 1 years, mean +/- SD), lean healthy normotensive male OHyp and 17 age- and sex-matched offspring of normotensive parents (ONorm) paired for baseline blood pressure with the OHyp. MAIN OUTCOME MEASURES: Resting and exercise blood pressure, body weight, body mass index (BMI) and waist-to-hip ratio were assessed at baseline and after 5 years. RESULTS: At baseline, body weight, BMI, waist-to-hip ratio and blood pressure did not differ significantly between OHyp and ONorm. At follow-up, body weight was increased in both groups (from 73.9 +/- 6.0 to 77.7 +/- 8.1 kg in OHyp, P = 0.008, and from 71.5 +/- 6.9 to 73.5 +/- 6.6 kg in ONorm, P = 0.03). BMI followed a similar pattern. In contrast, waist-to-hip ratio increased in OHyp (from 0.84 +/- 0.03 to 0.87 +/- 0.03, P = 0.012), but not in ONorm (from 0.84 +/- 0.03 to 0.84 +/- 0.04, P = 0.79) and was therefore higher in OHyp at follow-up (P = 0.011, OHyp versus ONorm). Peak systolic blood pressure during dynamic exercise also rose at 5 years in the OHyp (from 182 +/- 10 to 214 +/- 17 mmHg, P = 0.0001) while resting systolic blood pressure only tended to do so (from 121 +/- 7 to 128 +/- 12 mmHg, P = 0.07). In ONorm, resting and peak dynamic exercise systolic blood pressure remained unchanged (119 +/- 11 versus 121 +/- 9 mmHg, baseline versus follow-up, P = 0.40, and 186 +/- 12 versus 196 +/- 22 mmHg, P = 0.10, respectively). Thus, systolic peak exercise blood pressure was significantly (P = 0.014) elevated at follow-up in OHyp compared to ONorm, while resting systolic blood pressure only tended (P = 0.06) to do so. CONCLUSIONS: Initially lean normotensive OHyp have a disparate long-term course of central body fat as compared to ONorm. Thus, OHyp are not only genetically prone to develop hypertension, but they also have a particular propensity to accumulate central body fat, even before a distinct rise in resting blood pressure occurs. The exaggerated blood pressure response to exercise observed at follow-up in the OHyp represents another marker that confers them a greater risk of developing future hypertension.

Adipose Tissue↗
PubMed2003

Fasting blood glucose is independently associated with resting and exercise blood pressures and development of elevated blood pressure.

OBJECTIVE: To assess whether fasting blood glucose is independently related to blood pressure at rest and during exercise, and to development of elevated blood pressure. DESIGN: Cross-sectional and prospective cohort study of 2014 apparently healthy middle-aged men. METHODS: The baseline survey included carefully standardized blood pressure measurements at rest and during exercise testing, an intravenous glucose tolerance test and a panel of fasting blood tests, including fasting blood glucose. Results from 7-years follow-up provided data on development of elevated blood pressure. RESULTS: Strong associations were found between quartiles of fasting blood glucose and baseline resting and/or exercise levels of blood pressure, and also development of elevated blood pressure over 7 years. Physical fitness, calculated from an exercise test, had a strong modulating effect on blood pressure at all levels of fasting blood glucose. In multivariate models - after adjusting for intravenous glucose tolerance, physical fitness, age, body mass index, triglycerides and cholesterol - fasting blood glucose was strongly associated with blood pressure at rest (coefficient = 2.83, P = 0.0004) and during exercise (coefficient = 6.57, P < 0.0001), and further to development of treated hypertension and/or elevated blood pressure [odds ratio (OR), 1.17; 95% confidence interval (CI), 1.05-1.31]. CONCLUSION: In healthy non-diabetic and non-hypertensive men, strong associations were found between fasting blood glucose and blood pressure at rest and during exercise and to development of elevated blood pressure after 7-years follow-up. Fasting glucose metabolism deserves scrutiny when studying the pathogenesis of hypertension.

Adult↗
PubMed1994

Resting energy expenditure in infants with cystic fibrosis.

To evaluate the contribution of energy expenditure to the energy imbalance seen in cystic fibrosis patients, resting energy expenditure was measured using open-circuit indirect calorimetry in eight infants with cystic fibrosis, aged 2-7 months (mean, 4), without overt lung disease and in 10 healthy age-matched controls. In both groups, we found close, significant, linear correlations between resting energy expenditure and body weight and between resting energy expenditure and fat-free mass as measured by anthropometry. Cystic fibrosis patients had a 26% increase in resting energy expenditure per kilogram of fat-free mass as compared with controls and a 32% increase in resting energy expenditure as compared with predicted values for fat-free mass. These data from young infants free of clinical symptoms suggest a constitutional metabolic disorder in cystic fibrosis and support the need for early nutritional therapy in cystic fibrosis patients.

Anthropometry↗
PubMed1988

Alpha-adrenoceptor influence on plasma levels of neuropeptide Y-like immunoreactivity and catecholamines during rest and sympathoadrenal activation in humans.

Antecubital venous plasma neuropeptide Y-like immunoreactivity (NPY-LI) and catecholamines were analyzed in six healthy volunteers performing a graded bicycle exercise without medication and after acute administration of clonidine, phentolamine, and nifedipine. During the control exercise, plasma noradrenaline (NA), adrenaline (A), and NPY-LI increased to 17-, 7-, and 3-fold the resting values, respectively, at a maximal workload. Clonidine (300 micrograms p.o.) reduced resting and exercising heart rate (HR) and systolic blood pressure (SBP). Plasma NA at rest decreased and NA, A, and NPY-LI were 40-60% lower during the exercise after clonidine compared to the control. Phentolamine (0.07 mg X kg-1 every 10 min i.v.) and nifedipine (20 mg p.o.) increased HR and reduced SBP during the exercise. Plasma NA at rest was elevated threefold and the exercise-induced increases in NA and A were also enhanced after phentolamine. Plasma NPY-LI at rest was unchanged by phentolamine, while it was increased five-fold, as compared to the control, at the highest workload. Nifedipine slightly enhanced plasma NA and NPY-LI but not A during exercise. It is suggested that NPY is released mainly at high levels of sympathetic activity and that blood-pressure-lowering drugs acting on alpha adrenoceptors acutely influence the release of both NA and NPY-LI from sympathetic nerves in humans.

Adrenal Glands↗
PubMed1993

Differential effects of celiprolol and atenolol on large epicardial coronary arteries in conscious dogs at rest and during exercise.

The effects of celiprolol (1 mg/kg), a selective beta 1-adrenoceptor antagonist with partial agonist activity (PAA), on large and small coronary arteries and on systemic hemodynamics were investigated and compared with those of atenolol (1 mg/kg) and saline at rest and during three levels of treadmill exercise in the same 7 conscious dogs. Control exercise after saline administration induced increases in heart rate (HR 131 +/- 4%), left ventricular (LVdP/dt 117 +/- 5%), coronary blood flow (CBF 133 +/- 13%), and circumflex artery diameter (CxAD, 6.6 +/- 1.3%) and a decrease in coronary vascular resistance (CVR, -47 +/- 3%). Atenolol decreased LVdP/dt (-19 +/- 2%) and CxAD (-3.2 +/- 0.3%, p < 0.05) at rest, but large epicardial coronary arteries remained constricted during exercise (-4.7 +/- 1.4% at 12 km/h, p < 0.05) despite simultaneous dilation of coronary resistance vessels. In contrast to atenolol, celiprolol did not constrict large coronary arteries at rest (CxAD -0.2 +/- 0.9%, NS), and this beneficial effect of celiprolol was maintained throughout the exercise period. LVdP/dt was not modified and HR was slightly increased (14.3 +/- 2.6%) at rest by celiprolol. Atenolol and celiprolol reduced the exercise-induced positive inotropic and chronotropic effects, atenolol being the most potent. Thus, in dogs at rest when basal sympathetic tone was low, celiprolol, most likely because of its PAA, induced slight cardiac stimulation and prevented vasoconstriction of the large coronary arteries usually observed after beta-adrenoceptor blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

Dietary red pepper ingestion increases carbohydrate oxidation at rest and during exercise in runners.

The effects of dietary hot red pepper on energy metabolism at rest and during exercise were examined in long distance male runners 18-23 yr of age. A standardized meal was given on the evening prior to the experiment. The subjects had a meal (2720 kJ) with or without 10 g of hot red pepper for breakfast. During rest (2.5 h after meal) and exercise (pedaling for 1 h at 150 W, about 60% VO2max, using cycling ergometry), expired gasses and venous blood were collected. The meal with hot red pepper significantly elevated respiratory quotient and blood lactate levels at rest and during exercise. Oxygen consumption at rest was slightly but nonsignificantly higher in the hot red pepper meal at 30 min after the meal. Plasma epinephrine and norepinephrine levels were significantly higher in those who had only hot red pepper at 30 min after the meal. These results suggest that hot red pepper ingestion stimulates carbohydrate oxidation at rest and during exercise.

Adolescent↗
PubMed1998

Automated blood pressure measurement at rest and during exercise: evaluation of the motion tolerant CardioDyne NBP 2000.

PURPOSE: The purpose of this study was to validate the use of a motion tolerant blood pressure monitor (CardioDyne NBP 2000, Luxtec, Worcester, MA) ) against standard manual auscultation at rest and during exercise. METHODS: Nineteen subjects (men, N = 9; women, N = 10) participated in the study (mean: age 21+/-1.2 yr; height 172.5+/-8 cm; mass 69.4+/-14.5 kg). Standard Bruce protocol treadmill exercise tests with 12-lead ECG and metabolic measures were administered to the subjects, with blood pressure measures taken at rest before, during, and after the exercise tests. Blood pressure by manual auscultatory sphygmomanometry and the CardioDyne NBP 2000 was recorded simultaneously in the same arm. Manual auscultatory blood pressure measures obtained by one experimenter were used as the criterion measure, and the data of two NBP 2000 audio reviewers were averaged for each data point recorded. RESULTS: Systolic blood pressure (SBP) and diastolic blood pressure (DBP) via manual auscultation and the NBP 2000 "automatic" values were not significantly different and were highly correlated at rest and during exercise. Resting intraclass correlation SBP values were high (range 0.95 to 0.98), as were DBP intraclass correlation values (range 0.83 to 0.95). Exercise intraclass correlation SBP values ranged from 0.94 to 0.99, and DBP intraclass correlation values from 0.88 to 0.93. CONCLUSION: We conclude that the NBP 2000 is simple to use at rest and during exercise stress testing and provides accurate and verifiable information.

Adult↗
PubMedDate not supplied

Dysphoria among high-risk pregnant hospitalized women on bed rest: a longitudinal study.

BACKGROUND: While approximately 700,000 women experience pregnancy complications and are treated with bed rest in the hospital each year, little is known about negative affect in these women. OBJECTIVES: The study purpose was to describe dysphoria, a composite of symptoms of negative affect across the antepartum and postpartum and to identify the relationship between dysphoria and the length of pre-admission home bed rest, hospital bed rest, and maternal and fetal/neonatal indices of risk. METHODS: The convenience sample for this longitudinal repeated measures study consisted of 63 high-risk pregnant women admitted on antepartum bed rest to one of three university-affiliated hospitals. Women were included if they were diagnosed with (a) preterm labor, (b) premature rupture of membranes, (c) incompetent cervix, (d) placenta previa, (e) placental abruption or multiple gestation, and (f) did not have a psychiatric disorder. The Multiple Affect Adjective Checklist-Revised (MAACL-R) was used to assess dysphoria. Obstetric risk status was assessed by both the Hobel and Creasy Risk Assessment tools. RESULTS: Dysphoria was highest upon hospital admission and decreased significantly across time (F (5) = 23.58, p <.001). Positive Affect-Sensation Seeking significantly increased across time (F (5) = 53.16, p <.001). Dysphoria scores were significantly greater for those with highest Hobel obstetric risk scores (F (1, 60) = 4.53, p =.037). Antepartum dysphoria was not correlated with gestational age upon hospital admission, length of bed rest, or Creasy risk status. However, gestational age at birth was significantly correlated with postpartum dysphoria. DISCUSSION: The stimulus for antepartum dysphoria is unclear. However, postpartum dysphoria appears to be related to indicators of the infant's state of health at birth.

Abruptio Placentae↗
PubMedDate not supplied

Plasma catecholamines at rest and exercise in subjects with high- and low-trait anxiety.

The purpose of this study was to compare the plasma catecholamine concentration at rest and in response to exercise in subjects with low and high trait anxiety (TA). Six subjects with low TA and six subjects with high TA were selected among 149 males college students on the basis of their results on three TA tests (STAI, IPAT, 16 PF). Plasma norepinephrine (NE) and epinephrine (E) concentrations (pg/ml) were measured at rest in supine position and during mild and moderate exercises of 5 min duration (about 40% and 60% of the individual VO2max) on bicycle ergometer. Plasma E concentrations at rest and exercise were not significantly different in subjects with low (33 +/- 6, 82 +/- 11, and 197 +/- 49) or high TA (41 +/- 7, 62 +/- 13, and 229 +/- 52). Plasma NE concentration was not significantly different at rest and in response to mild exercise in low (235 +/- 52; 666 +/- 64) and high-TA subjects (223 +/- 36; 610 +/- 88) but was significantly higher in high-TA than in low-TA subjects in response to moderate exercise (2510 +/- 618 vs. 1243 +/- 234). These results show 1) that plasma NE and E concentrations at rest and in response to light exercise are similar in low- and high-TA subjects, and 2) that subjects with high TA have a greater plasma NE response to the psychologic stress and/or to the homeostatic challenge of moderate exercise.

Adolescent↗
PubMed2001

The effects of creatine dietary supplementation on anterior compartment pressure in the lower leg during rest and following exercise.

OBJECTIVE: To examine the effects of creatine supplementation on anterior compartment pressure of the lower leg at rest and following exercise. DESIGN: 14 college-age males received creatine or placebo supplementation for 34 days. At baseline, anterior compartment pressure was measured preexercise, immediately postexercise, and 1, 5, and 15 minutes postexercise after a level treadmill run for 20 minutes at 80% of maximal aerobic power. INTERVENTION: Following baseline testing, subjects began a 6-day creatine or placebo loading phase at a dosage of 0.3 g x kg body mass(-1) x d(-1). This was followed by a 28-day maintenance phase at a dosage of 0.03 g x kg body mass(-1) x d(-1). Subjects and investigators were blinded as to treatment administration. Subjects continued to exercise during the supplementation period. After 6 days and 34 days of supplementation. anterior compartment pressure was measured at rest and following exercise. RESULTS: Creatine supplementation for 6 days significantly increased compartment pressure compared with the placebo group at rest (76%), immediately post- (150%), 1 minute post- (125%), 5 minute post- (106%), and 15 minute postexercise (77%). Anterior compartment pressures continued to remain significantly higher for the creatine group compared with the placebo group at rest (72%), immediately post- (125%) and 1 minute postexercise (180%) after 34 days of creatine supplementation. CONCLUSIONS: These data indicate that creatine supplementation abnormally increases anterior compartment pressure in the lower leg at rest and following 20 minutes of level running at 80% of maximal aerobic power.

Adenosine Triphosphate↗