Endothelium-dependent vasodilation of the skin microcirculation in heart transplant recipients

The aim of this study was to compare the exercise intensity and rating of perceived exertion (RPE) of a high-impact (HIP) and a low-impact (LIP) university aerobic dance session. Ten women [mean (SD) age 22.9 (2.6) years] took part in the study. An incremental treadmill test was performed by each subject to determine maximum oxygen consumption (VO2max) and maximum heart rate (HRmax). The measured VO2max [mean (SD)] was 49.0 (7.5) ml x kg(-1) x min(-1). The subjects were randomly assigned to LIP and HIP sessions (i.e. five of the subjects participated in the HIP session first, and the other five participated in the LIP session first). In a laboratory, heart rate, oxygen uptake and RPE were measured throughout each session for each subject. Expired air was collected continuously throughout the sessions using Douglas bags (ten bags over a 30-min period). The sessions consisted of 20 min of aerobic exercise (bags 1-7) followed by 5 min of local muscular endurance exercise (bags 8 and 9) and 5 min of flexibility exercises (bag 10). The mean intensity of the aerobic section of the LIP and HIP sessions was 51.6% and 64.7% VO2max, respectively. Ninety-five percent confidence intervals for the average difference between the HIP and LIP sessions demonstrate that the %VO2max was between 12% and 14% higher for the HIP session. The mean %HRmax for the LIP and HIP sessions was 71.4% and 76.7%, respectively, with the %HRmax in the HIP session being between 5.4% and 7.2% higher on average than that of the LIP session. On average, the RPE for the aerobic section of the HIP session (12.1) was consistently higher than that of the LIP session (11.1). HIP activity has the potential to maintain/improve the aerobic fitness of its participants. According to the literature, the exercise intensity elicited by LIP activity may have a limited training effect for the population utilised in this study, and for some individuals may result in detraining. Conversely, LIP activities may be an appropriate mode of exercise for overweight and unfit individuals.     

Ratings of perceived exertion (RPE) during cycling exercises at constant power output

The purpose of the present investigation was to study the overall rating of perceived exertion (RPEov) according to the 6-20 scale proposed by Borg (1970) and muscular RPE (RPEmu) in exercises at constant load. The relationship between RPE and heart rate for three different loads was studied during exhausting exercises in 10 participants. Whether the drift of RPE during a 20 min exercise at constant load could be an index of the endurance time during long-lasting exercises at constant load was also investigated. At 1-week intervals, the participants performed cycling exercises up to exhaustion at 60, 73, and 86% maximal aerobic power (MAP) measured during an incremental test. Heart rate, RPEov, RPEmu and exhaustion time (tlim) were measured. The upward shift of the HRmax-RPE regressions was significant between 86, 73 and 60% MAP (p < 0.001) for RPEov and RPEmu. This result suggests that the equation HR = 10 x RPE proposed by Borg (1973) for incremental exercise is not valid for long-lasting exercise at constant load until exhaustion because the heart rate corresponding to a given RPE depends on load and time. Mean RPE increased linearly with time up to exhaustion. Unexpectedly, the relationships between RPEmu or RPEov and percentage of exhaustion time were similar for exercises at 60 and 73% MAP although the exhaustion times were very different (79.40 +/- 30.64 min versus 36.19 +/- 15.99 min, respectively) (p < 0.001). Consequently, it is likely that RPE was a subjective estimation of the hardness of exercise rather than the intensity of exercise. The RPE pattern at the beginning of long-lasting exercises at constant load (60 and 73% MAP) cannot be considered as a sensitive predictor of the point of self-imposed exhaustion for individuals. Indeed, the errors in the estimation of exhaustion time from extrapolation of RPE at the beginning of exercise were very large. Moreover, at 60% MAP, a steady-state in RPE was observed during 20 min in five subjects whose tlim were not longer than tlim of the other subjects. In addition, the data of the present study indicate that RPEmu could be more useful than RPEov in cycling.     

Effects of endurance training and heat acclimation on psychological strain in exercising men wearing protective clothing

Two experiments examined the influences of endurance training and heat acclimation on ratings of perceived exertion (RPE) and thermal discomfort (RTD) during exercise in the heat while wearing two types of clothing. In experiment 1, young men underwent 8 weeks of physical training [60-80% of maximal aerobic power (VO2max) for 30-45 min day-1, 3-4 days week-1 at 20-22 degrees C dry bulb (db) temperature] followed by 6 days of heat acclimation [45-55% VO2max for 60 min day-1 at 40 degrees C db, 30% relative humidity (rh)] (n = 7) or corresponding periods of control observation followed by heat acclimation (n = 9). In experiment 2, young men were heat-acclimated for 6 or 12 days (n = 8 each). Before and after each treatment, subjects completed bouts of treadmill exercise (1.34 m s-1, 2% grade in experiment 1 and 0% grade in experiment 2) in a climatic chamber (40 degrees C db, 30% rh), wearing in turn normal light clothing (continuous exercise at 37-45% VO2max for a tolerated exposure of 116-120 min in experiment 1 and at 31-34% VO2max for 146-150 min in experiment 2) or clothing protective against nuclear, biological, and chemical agents (continuous exercise at 42-51% VO2max for a tolerated exposure of 47-52 min in experiment 1 and intermittent exercise at 23% VO2max for 97-120 min in experiment 2). In experiment 1, when wearing normal clothing, endurance training and/or heat acclimation significantly decreased RPE and/or RTD at a fixed power output. There were concomitant reductions in relative work intensity (% VO2max) [an unchanged oxygen consumption (VO2) but an increased VO2max, or a reduced VO2 with no change of VO2max], rectal temperature (Tre), mean skin temperature (Tsk), and/or heart rate (HR). When wearing protective clothing, in contrast, there were no significant changes in RPE or RTD. Although training and/or acclimation reduced %VO2max or Tre, any added sweat that was secreted did not evaporate through the protective clothing, thus increasing discomfort after training or acclimation. Tolerance times were unchanged in either normal or protective clothing. In experiment 2, when wearing normal clothing, heat acclimation significantly decreased RPE and RTD at a fixed power output, with concomitant reductions in Tre, Tsk, and HR; the response was greater after 12 than after 6 days of acclimation, significantly so for RPE and HR. When wearing protective clothing, the subjects exercised at a lower intensity for a longer duration than in the moderate exercise trial. Given this tactic, either 6 or 12 days of heat acclimation induces significant reductions RPE and/or RTD, accompanied by reductions in Tre, Tsk, and/or HR. Tolerance times in protective clothing were also increased by 11-15% after acclimation, despite some increase of sweat accumulation in the protective clothing. The results suggest that (1) neither endurance training nor heat acclimation reduce psychological strain when protective clothing is worn during vigorous exercise, because increased sweat accumulation adds to discomfort, and (2) in contrast to the experience during more vigorous exercise, heat acclimation is beneficial to the subject wearing protective clothing if the intensity of effort is kept to a level that allows permeation of sweat through the clothing. This condition is likely to be met in most modern industrial applications.     

Exercise mode and gender comparisons of energy expenditure at self-selected intensities

The purpose of this study was to compare oxygen consumption (VO2) and energy expenditure after 20 min of self-selected submaximal exercise for four modes of exercise. Eighteen subjects (9 male and 9 female) first completed a test of VO2max during treadmill running. On separate days, subjects then completed 20 min submaximal treadmill running (TR), simulated cross-country skiing (XC), cycle ergometry (CE), and aerobic riding (AR) exercise. Total VO2 and energy expenditure were significantly higher for TR than all other modes for both males and females (43.6 +/- 10.4, 39.1 +/- 9.7, 36.1 +/- 7.6, 28.4 +/- 6.1 LO2, for TR, XC, CE, and AR, respectively, P < 0.0001). For males and females, heart rate was similar during TR and XC and lower during CE and AR (154.8 +/- 14.2, 152 +/- 13.1, 143.4 +/- 14.9, and 126.2 +/- 12.0 beats.min-1 for TR, XC, CE, and AR, respectively, P < 0.0001). Compared with females, males had significantly greater VO2 (P < 0.005) and energy expenditure (P < 0.004), while females had higher heart rates (P < 0.003). Ratings of perceived exertion (RPE) were not different between TR, XC, and CE, but were significantly lower during AR (13.4 +/- 1.3, 13.6 +/- 0.8, 13.2 +/- 0.9, and 12.6 +/- 1.0 for TR, XC, CE, and AR, respectively, P < 0.003). TR elicited the greatest VO2 and energy expenditure during self-selected exercise despite and RPE similar to XC and CE. Therefore, treadmill exercise may be the modality of choice for individuals seeking to improve cardiorespiratory endurance and expend a larger number of kjoules.     

Perceived exertion associated with breathing hyperoxic mixtures during submaximal work

The effect of an enriched inspired oxygen concentration on perceived exertion (RPE) was investigated while running at two submaximal treadmill loads. Twelve males (VO2 max = 49.3 ml/kg-min) worked at 50% and 80% VO2 max, breathing either air or 80% O2-20% N2 in random order using a single blind technique. Subjects were evaluated while running for 10 min and during a 20 min recovery. Heart rate (HR), ventilation (VE), respiration rate (RR), tidal volume (VT) and RPE were measured before, during and after work. Blood lactate was measured 1 min after work. Oxygen concentration did not statistically affect HR, VE, RR or VT during exercise or recovery. At both loads, RPE at the end of exercise was significantly reduced breathing the hyperoxic mixture. At 50% VO2 max, mean RPE decreased from 11.2 breathing room air to 9.6 breathing 80% O2 and, 80% VO2 max, from 13.8 to 11.7 (P less than 0.01). Blood lactates were significantly reduced breathing 80% O2; from 23.4 mg to 13.3 at 50% VO2 max and from 55.5 to 36.5 at 80% VO2 max (P less than 0.01). The RPE correlated with lactate (r=0.64) at the end of work. Results indicate that during moderate and heavy work RPE is significantly affected by the inspired O2 concentration and there is a significant relationship between RPE and blood lactate.     

Heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress

The purpose of the present study was to determine the separate and combined effects of aerobic fitness, short-term heat acclimation, and hypohydration on tolerance during light exercise while wearing nuclear, biological, and chemical protective clothing in the heat (40 degrees C, 30% relative humidity). Men who were moderately fit [(MF); <50 ml . kg-1 . min-1 maximal O2 consumption; n = 7] and highly fit [(HF); >55 ml . kg-1 . min-1 maximal O2 consumption; n = 8] were tested while they were euhydrated or hypohydrated by approximately 2.5% of body mass through exercise and fluid restriction the day preceding the trials. Tests were conducted before and after 2 wk of daily heat acclimation (1-h treadmill exercise at 40 degrees C, 30% relative humidity, while wearing the nuclear, biological, and chemical protective clothing). Heat acclimation increased sweat rate and decreased skin temperature and rectal temperature (Tre) in HF subjects but had no effect on tolerance time (TT). MF subjects increased sweat rate but did not alter heart rate, Tre, or TT. In both MF and HF groups, hypohydration significantly increased Tre and heart rate and decreased the respiratory exchange ratio and the TT regardless of acclimation state. Overall, the rate of rise of skin temperature was less, while DeltaTre, the rate of rise of Tre, and the TT were greater in HF than in MF subjects. It was concluded that exercise-heat tolerance in this uncompensable heat-stress environment is not influenced by short-term heat acclimation but is significantly improved by long-term aerobic fitness.     

Effects of artificially-induced anaemia on sudomotor and cutaneous blood flow responses to heat stress

The influence of artificially induced anaemia on thermal strain was evaluated in trained males. Heat stress trials (38.6 degrees C, water vapour pressure 2.74 kPa) performed at the same absolute work rates [20 min of seated rest, 20 min of cycling at 30% peak aerobic power (VO2pcak), and 20 min cycling at 45% VO2peak] were completed before (HST1) and 3-5 days after 3 units of whole blood were withdrawn (HST2). Mild anaemia did not elevate thermal strain between trials, with auditory canal temperatures terminating at 38.5 degrees C [(0.16), HST1] and 38.6 degrees C [(0.13), HST2; P > 0.05]. Given that blood withdrawal reduced aerobic power by 16%, this observation deviates from the close association often observed between core temperature and relative exercise intensity. During HST2, the absolute and integrated forearm sweat rate (mSW) exceeded control levels during exercise (P < 0.05), while a suppression of forehead mSW occurred (P < 0.05). These observations are consistent with a possible peripheral redistribution of sweat secretion. It was concluded that this level of artificially induced anaemia did not impact upon heat strain during a 60-min heat stress test.     

Relationship between nitric oxide and prostaglandins in carrageenin pleurisy

PURPOSE: To examine the effects of repeated bouts of exercise on the blood lactate [HLa]-ratings of perceived exertion (RPE) relation. METHODS: Six moderately trained males were studied on two occasions: a sequential exercise bouts day (SEB: 1000 h, 1130 h, and 1300 h) and a delayed exercise bouts day (DEB: 1000 h, 1400 h, and 1800 h). Each of the three exercise bouts within a given condition were 30 min in duration at the power output (PO) associated with 70% of VO2peak on a cycle ergometer. A standardized meal was provided at 0600 h. VO2, PO, HR, and RER were recorded every min during exercise and blood [HLa] and RPE were measured every 5 min during exercise. RESULTS: A 2 x 3 analysis of variance with repeated measures revealed that blood [HLa] decreased significantly with each repeated exercise bout (X +/- SEM: bout 1: SEB = 3.5 (0.3), DEB = 3.8 (0.4); bout 2: SEB = 2.6 (0.3), DEB = 2.8 (0.3); bout 3: SEB = 2.0 (0.2), DEB = 2.1 (0.4); mM). No differences were observed in the blood [HLa] response to repeated bouts of exercise between SEB and DEB. RPE-peripheral (legs, RPE-L) was higher during bout 3 compared with bout 1 (P <0.05) (bout 1: SEB = 11.8 (0.8), DEB = 12.3 (0.2); bout 2: SEB = 12.3 (0.5), DEB = 13.3 (0.4); bout 3: SEB = 13.5 (0.8), DEB = 14.0 (0.7); RPE-central (chest and breathing, RPE-C) was not affected by repeated bouts of exercise, whereas RPE-Overall (RPE-O) was higher during bout 3 compared with bouts 1 and 2 (P < 0.05) (bout 1: SEB = 12.5 (0.2), DEB = 12.3 (0.4); bout 2: SEB = 12.8 (0.4), DEB = 12.7 (0.4); bout 3: SEB = 13.7 (0.7), DEB = 13.2 (0.3)). No interaction for RPE x condition was observed. HR increased with repeated bouts of exercise with HR during exercise bout 3 being higher than HR during exercise bout 1 (164 vs. 156 bpm, P < 0.05). There was also a strong trend for HR during exercise bout 3 to be higher than HR during exercise bout 2 (P < 0.06). A trend for a reduction in VO2 with repeated exercise was observed (P < 0.07), with the reduction apparently related to the SEB condition (P < 0.12 for VO2 x condition). PO and kcal.min-1 were not affected by repeated bouts of exercise. RER decreased significantly with each repeated bout of exercise (from RER = 0.96 to RER = 0.89, P < 0.05) with no difference observed between SEB and DEB. CONCLUSIONS: We conclude that the blood [HLa]-RPE relation is altered by repeated bouts of exercise and that this alteration does not appear to be affected by recovery time between exercise bouts (up to 3.5 h of recovery). These data suggest that, after the first exercise bout, RPE should not be used to produce a specific blood [HLa] on subsequent exercise bouts.     

Caffeine, performance, and metabolism during repeated Wingate exercise tests

Investigations examining the ergogenic and metabolic influence of caffeine during short-term high-intensity exercise are few in number and have produced inconsistent results. This study examined the effects of caffeine on repeated bouts of high-intensity exercise in recreationally active men. Subjects (n = 9) completed four 30-s Wingate (WG) sprints with 4 min of rest between each exercise bout on two separate occasions. One hour before exercise, either placebo (P1; dextrose) or caffeine (Caf; 6 mg/kg) capsules were ingested. Caf ingestion did not have any effect on power output (peak or average) in the first two WG tests and had a negative effect in the latter two exercise bouts. Plasma epinephrine concentration was significantly increased 60 min after Caf ingestion compared with P1; however, this treatment effect disappeared once exercise began. Caf ingestion had no significant effect on blood lactate, O2 consumption, or aerobic contribution at any time during the protocol. After the second Wingate test, plasma NH3 concentration increased significantly from the previous WG test and was significantly higher in the Caf trial compared with P1. These data demonstrate no ergogenic effect of caffeine on power output during repeated bouts of short-term, intense exercise. Furthermore, there was no indication of increased anaerobic metabolism after Caf ingestion with the exception of an increase in NH3 concentration.     

Effects of ambient temperature on the capacity to perform prolonged cycle exercise in man

Eight healthy males performed four rides to exhaustion at approximately 70% of their VO2max obtained in a neutral environment. Subjects cycled at ambient temperatures (Ta) of 3.6 +/- 0.3 (SD), 10.5 +/- 0.5, 20.6 +/- 0.2, and 30.5 +/- 0.2 degrees C with a relative humidity of 70 +/- 2% and an air velocity of approximately 0.7 m.s-1. Weighted mean skin temperature (Tsk), rectal temperature (Tre), and heart rate (HR) were recorded at rest, during exercise and at exhaustion. Venous samples were drawn before and during exercise and at exhaustion for determination of hemoglobin, hematocrit, blood metabolites, and serum electrolytes and osmolality. Expired air was collected for calculation of VO2 and R which were used to estimate rates of fuel oxidation. Ratings of perceived exertion (RPE) were also obtained. Time to exhaustion was significantly influenced by Ta (P = 0.001): exercise duration was shortest at 30.5 degrees C (51.6 +/- 3.7 min) and longest at 10.5 degrees C (93.5 +/- 6.2 min). Significant effects of Ta were also observed on VE, VO2, R, estimated fuel oxidation, HR, Tre, Tsk, sweat rate, and RPE. This study demonstrates that there is a clear effect of temperature on exercise capacity which appears to follow an inverted U relationship.     

Response to exercise in patients after repair of tetralogy of Fallot

Cardiac catheterization and submaximal exercise testing was performed in 38 patients after repair of tetralogy of Fallot (TF), and compared to 6 control patients who had functional murmurs. Cardiac index, heart rate, and stroke volume index were significantly lower in the TF group than in the control group. Right and left ventricular end-diastolic pressure increased significantly during exercise, which was not found in the control group. Total pulmonary vascular resistance (TPVR), which decreased significantly with exercise in the control group, did not change remarkably during exercise. TPVR was significantly higher in the TF group than in the control group both at rest and during exercise. Several factors were compared between patients with good cardiac index (> 5.0 l/min/m2; Group 1) and poor cardiac index (< 5.0 l/min/m2; Group 2) during exercise. Stroke volume index, right ventricular ejection fraction at rest were significantly higher in Group 1 than Group 2. TPVR, right and left ventricular end-diastolic and end-systolic volume index were significantly lower in Group 1 than in Group 2. There was no significant difference in heart rate, left ventricular ejection fraction, residual pulmonary stenosis, right to left ventricular systolic pressure ratio, and severity of pulmonary regurgitation between two groups. These findings indicate that abnormalities of exercise tolerance in patients after repair of TF were related to poor response of heart rate, pulmonary vascular resistance, and systolic and diastolic ventricular function.     

Dynamic exercise therapy in rheumatoid arthritis: a systematic review

The aim of this systematic review was to determine the effectiveness of dynamic exercise therapy in improving joint mobility, muscle strength, aerobic capacity and daily functioning in patients with rheumatoid arthritis (RA). In addition, possible unwanted effects such as an increase in pain, disease activity and radiological progression were studied. A computer-aided search of the MEDLINE, Embase and SCISEARCH databases was performed to identify controlled trials on the effect of exercise therapy. Randomized trials were selected on the effect of dynamic exercise therapy in RA patients with an exercise programme fulfilling the following criteria: (a) intensity level such that heart rates exceeded 60% of maximal heart rate during at least 20 min; (b) exercise frequency > or = 2 a week; and (c) duration of intervention > or = 6 weeks. Two blinded reviewers independently selected eligible studies, rated the methodological quality and extracted data. Six out of 30 identified controlled trials met the inclusion criteria. Four of the six included studies fulfilled > or = 7/10 methodological criteria. Because of heterogeneity in outcome measures, data could not be pooled. The results suggest that dynamic exercise therapy is effective in increasing aerobic capacity and muscle strength. No detrimental effects on disease activity and pain were observed. The effects of dynamic exercise therapy on functional ability and radiological progression are unclear. It is concluded that dynamic exercise therapy has a positive effect on physical capacity. Research on the long-term effect of dynamic exercise therapy on radiological progression and functional ability is needed.     

Nitric oxide inhibited peroxyl and alkoxyl radical formation with concomitant protection against oxidant injury in intestinal epithelial cells

Respiratory sinus arrhythmia (RSA) was examined in aerobically trained (AT) and untrained (NT) college-aged males during 12 periods consisting of a 3-min sitting baseline, six common 3-min absolute exercise stages, and five 3-min recovery stages that followed voluntary exhaustion to determine the relationship of work and training status to parasympathetic influence upon the heart. RSA systematically decreased during absolute exercise, was observed at heart rates (HR) above 100 beats x min(-1), and progressively increased during recovery. Additionally, independent of work stages, comparative regression analyses were conducted for both the exercise and recovery phases, separately, in which HR was regressed on RSA, as well as RSA on % VO2max, to contrast the obtained relationships for the AT and NT. No differences were revealed as a function of endurance training status as the slopes and intercepts obtained for the two groups from each of these analyses were similar. The within-subject correlations between RSA and % VO2max, calculated for each of the individuals across all 12 periods, were consistently negative. Between-subjects correlations of RSA with RR and tidal volume were predominantly nonsignificant, indicating that RSA, as measured here, is independent of individual differences in ventilatory activity and, as such, can be compared between groups during exercise. The findings demonstrate that RSA is detectable during both exercise and recovery, even at HR beyond 100 beats x min(-1), and reveals a similar relationship to HR and metabolic state in both aerobically trained and untrained populations.     

State anxiety and ambulatory blood pressure following resistance exercise in females

The purpose of this investigation was to examine state anxiety and blood pressure responses during ambulatory recovery from resistance exercise. Fourteen females completed three separate bouts of resistance exercise in which the sets (N = 3), repetitions (N = 10), exercise type (knee extension, knee flexion, arm pull down, chest press, shoulder press, and abdominal curl), and time (30 min) were held constant, but the intensity was manipulated to equal 40%, 60%, and 80% of the 10-repetition maximum for each exercise. Immediately before as well as 1, 15, 30, 45, 60, 75, 90, 105, and 120 min following the cessation of exercise blood pressure and heart rate were assessed. State anxiety assessments were initiated immediately following blood pressure measurements. The subjects were ambulatory during the post-exercise period, and information about body posture during the cardiovascular assessments was obtained. MANOVAs, ANOVAs, and Tukey tests revealed that post-exercise state anxiety levels were reduced compared with pre-exercise values from 90 to 120 min following exercise. Systolic blood pressure was elevated at 1 and 15 min following the 80% intensity condition, and at 1 min following the 60% intensity condition. It is concluded that during ambulatory recovery from resistance exercise: 1) reductions in state anxiety are realized; and 2) systolic blood pressure, in contrast to what has been shown to occur following aerobic exercise, is not reduced.     

Sarcoidosis and cancer revisited: a long-term follow-up study of 555 Danish sarcoidosis patients

STUDY OBJECTIVE: To determine whether an aerobic endurance training program (AET) in comparison to normal daily activities improves exercise capacity in lung transplant recipients. PATIENTS AND STUDY DESIGN: Nine lung transplant recipients (12+/-6 months after transplant) were examined. All patients underwent incremental bicycle ergometry with the work rate increased in increments of 20 W every 3 min. Identical exercise tests were performed after 11+/-5 weeks of normal daily activities and then after a 6-week AET. The weekly aerobic training time increased from 60 min at the beginning to 120 min during the last week. Training intensity ranged from 30 to 60% of the maximum heart rate reserve. RESULTS: Normal daily activities had no effect on exercise performance. The AET induced a significant decrease in resting minute ventilation from 14+/-5 to 11+/-3 L/min. At an identical, submaximal level of exercise, a significant decrease in minute ventilation from 47+/-14 L/min to 39+/-13 L/min and heart rate from 144+/-12 to 133+/-17 beats/min, before and after the AET, was noted. The increase in peak oxygen uptake after AET was statistically significant (1.13+/-0.32 to 1.26+/-0.27 L/min). CONCLUSIONS: These data demonstrate that normal daily activities do not affect exercise performance in lung transplant recipients > or = 6 months after lung transplantation. An AET improves submaximal and peak exercise performance significantly.     

Metabolic effects of facial cooling in exercise

Metabolic responses to facial cooling during prolonged exercise was investigated in five male subjects. Exercise on a bicycle ergometer at 50 rpm for 1 h at 60% maximal heart rate was performed twice, once with cold wind (10 degrees C, 6.5 m . s-1) and once without. Resting experiments were conducted under identical conditions. Facial cooling apparently had no effect on plasma FFA or glucose concentration during exercise but did, however, result in significantly (p less than 0.05) greater fat utilization, as indicated by lower respiratory exchange ratios at 60 min of exercise. The respiratory exchange ratio, blood lactate concentration, oxygen consumption, and estimated myocardial oxygen consumption at 5 min of exercise were higher with facial cooling. The results suggest that metabolic changes occur with facial cooling that are related to a general thermoregulatory response and that the stress of exercise is greater with facial cooling.     

Acute exercise: Buffering psychosocial stress responses in women.

48 25–40 yr old women participated in 2 counterbalanced experimental conditions: an attention control and a 40-min bout of aerobic exercise (AE) at 70% heart rate (HR) reserve. The attention control and AE treatments were followed by (1) 30 min of quiet rest, (2) exposure to mental and interpersonal threat, and (3) 5 min of recovery. Blood pressure (BP) and HR were monitored at baseline, during the stressors, and throughout recovery. Self-reported distress was assessed before each stressor and upon completion of the recovery period. Results provide clear evidence that exercise dampened BP reactivity to psychosocial stress. Compared with the attention placebo control, AE reduced both the frequency and intensity of anxiety-related thoughts that occur in anticipation of interpersonal threat and challenge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perioperative growth hormone treatment increases nitrogen and fluid balance and results in short-term and long-term conservation of lean tissue mass

STUDY OBJECTIVE: To evaluate changes due to pregnancy on atenolol's pharmacokinetics, response of maternal heart rate to atenolol, and the drug's effect on fetal heart rate. DESIGN: Prospective study. SETTING: Large university teaching hospital. PATIENTS: Fourteen pregnant women who were receiving oral atenolol for cardiac disease were enrolled and 10 completed the study. INTERVENTIONS: Patients were studied for 12 hours during the third trimester (TT) and again 6 weeks postpartum (PP). MEASUREMENTS AND MAIN RESULTS: Fetal heart rates, and maternal heart rates at rest and during exercise were recorded. Maternal plasma and urine atenolol concentrations were measured. Average resting heart rates (TT 68+/-10, PP 62+/-9 beats/min) and maximum heart rate during exercise (TT 100+/-6, PP 87+/-7 beats/min) were significantly higher in the third trimester than postpartum (p<0.05). The 12-hour atenolol area under the curve (TT 0.208+/-0.061, PP 0.215+/-0.089 ng/ml/day) and maximum plasma concentrations during the time of exercise tests (TT 1.07+/-0.39, PP 1.14+/-0.53 mmol/L) were not significantly different. Individual and population pharmacokinetics did not differ significantly between study periods. The fetal heart rate did not correlate with maternal atenolol concentration. CONCLUSION: Constant dosages of atenolol result in higher heart rates during pregnancy compared with the postpartum period. This lack of heart rate control is not due to significant changes in atenolol's pharmacokinetics or plasma concentrations.     

Central and regional circulatory effects of adding arm exercise to leg exercise

7 young, healthy, male subjects performed exercise on bicycle ergometers in two 20 min periods with an interval of 1 h. The first 10 min of each 20 min period consisted of arm exercise (38--62% of Vo2 max for arm exercise) or leg exercise (58--78% of Vo2 max for leg exercise). During the last 10 min the subjects performed combined arm and leg exercise (71--83% of Vo2 max for this type of exercise). The following variables were measured during each type of exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow (only during leg exercise and combined exercise), arterio-venous concentration differences for O2 and lactate at the levels of the axillary and the external iliac vessels. Superimposing a sufficiently strenuous arm exercise (oxygen uptake for arm exercise greater than 40% of oxygen uptake for combined exercise) on leg exercise caused a reduction in blood flow and oxygen uptake in the exercising legs with unchanged mean arterial blood pressure. Superimposing leg exercise on arm exercise caused a decrease in mean arterial blood pressure and an increased axillary arterio-venous oxygen difference. These findings indicate that the oxygen supply to one large group of exercising muscles may be limited by vasoconstriction or by a fall in arterial pressure, when another large group of muscles is exercising simultaneously.     

Reliability of a handgrip test for evaluating heart rate and pressor responses in multiple sclerosis

PURPOSE: The purpose of this study was to determine the test-retest reliability of an isometric handgrip exercise protocol designed to evaluate heart rate and arterial pressure responses in individuals with multiple sclerosis (MS). METHODS Three males and eleven females, aged 24 through 51, performed isometric handgrip contractions at 30% of maximal voluntary contraction (MVC) to the point of fatigue (defined as inability to maintain the target force for three consecutive seconds). During this exercise, rate of perceived exertion (RPE) was recorded every 30 s. Heart rate and beat-to-beat systolic, diastolic, and mean arterial pressures were recorded continuously throughout the duration of exercise. Surface EMG was monitored continuously via loudspeaker to provide feedback on extraneous muscular activity. Each subject performed three trials. A repeated measures ANOVA was used to calculate interclass reliability estimates for each dependent variable. RESULTS: Reliability estimates for MVC and time to fatigue were 0.98 and 0.84, respectively. Reliability estimates for the following dependent variables at the point of fatigue were: RPE, 0.90; delta HR, 0.97; delta systolic pressure, 0.92; delta diastolic pressure, 0.87; and delta MAP, 0.88. CONCLUSIONS: We conclude that this isometric handgrip protocol is a reliable method for evaluating heart rate and blood pressure responses in MS patient.