Physiological responses to incremental exercise in patients with chronic fatigue syndrome.

PURPOSE: The purpose of this investigation was to characterize the physiological response profiles of patients with chronic fatigue syndrome (CFS), to an incremental exercise test, performed to the limit of tolerance. METHODS: Fifteen patients (12 women and three men) who fulfilled the case definition for chronic fatigue syndrome, and 15 healthy, sedentary, age- and sex-matched controls, performed an incremental progressive all-out treadmill test (cardiopulmonary exercise test). RESULTS: As a group, the CFS patients demonstrated significantly lower cardiovascular as well as ventilatory values at peak exercise, compared with the control group. At similar relative submaximal exercise levels (% peak VO(2)), the CFS patients portrayed response patterns (trending phenomenon) characterized, in most parameters, by similar intercepts, but either lower (VCO(2), HR, O(2pulse), V(E), V(T), PETCO(2)) or higher (B(f), V(E)/VCO(2)) trending kinetics in the CFS compared with the control group. It was found that the primary exercise-related physiological difference between the CFS and the control group was their significantly lower heart rate at any equal relative and at maximal work level. Assuming maximal effort by all (indicated by RER, PETCO(2), and subjective exhaustion), these results could indicate either cardiac or peripheral insufficiency embedded in the pathology of CFS patients. CONCLUSION: We conclude that indexes from cardiopulmonary exercise testing may be used as objective discriminatory indicators for evaluation of patients complaining of chronic fatigue syndrome.

Normal cardiopulmonary responses during incremental exercise in 20- to 70-yr-old men.

Healthy men (N = 1424, age 20-70 yr) underwent a progressive incremental treadmill exercise test to volitional maximum. Cardiopulmonary variables were measured breath-by-breath. The aerobic power (VO2max) declined at an average yearly rate of 0.33 ml.kg.-1min-1, HRmax declined 0.685 beats.min-1.yr-1, and max O2 pulse declined at an annual rate of 0.115 ml.beat-1.kg-1*100. Gas exchange threshold (GET) expressed as percentage of VO2max was 58% and 69% in the youngest (20-30 yr) and oldest (61-70 yr) decades, respectively. The average decline in VE, Vt, f, and PETCO2 over the entire age range was 29%, 10%, 21%, and 7%, respectively. There were increases in VE/VO2, and VE/VECO2, from age 20-70 yr of 13% and 14%, respectively, but no changes across 5 decades in PETO2. Physical (height and weight) as well as life-style characteristics (leisure time activity, place of residency, smoking), were found to be potent predictors in most of the cardiopulmonary values at maximal exercise and therefore should be incorporated in the predictive equations for such variables. Normal response patterns of most cardiopulmonary variables throughout the range of exercise intensities were shown to be age-affected and thus should be standardized for age decades.

Prevalence of smoking among Israeli male athletes.

A survey of smoking habits was carried out on 2447 males age 14-40 years. The subjects were athletes trained in a wide variety of sports. Overall 15.5% of the athlete population were smokers. When broken down into training groups, the highest smoking prevalence was reported by subjects not engaged in specific training, while the lowest prevalence was reported by endurance trained athletes. When divided into specific sports, the highest percent of group smoking was found in soccer players. Smoking prevalence increased with increasing age. No significant differences in smoking prevalence existed between groups of varying ethnic origin. This study provides data on groups of athletes to target in smoking intervention programs.

Reexamination of Stewart's quantitative analysis of acid-base status.

To provide experimental verification to Stewart's quantitative approach to acid-base analysis, the effects of acute maximal treadmill exercise (VO2max test) on venous acid base status were studied in 17 male subjects aged 18-23 yr. Venous CO2 tension (PCO2) total plasma proteins ([PTOT]), [H+], and concentrations of strong ions [( Na+], [K+], [Cl-] and lactate ion concentration ([La-]) were measured before and within 1 min post-exercise. Mean post-exercise PCO2, [PTOT], [K+], and [La-] were significantly higher than the corresponding pre-exercise values (P less than 0.05), there was a strong tendency for a significant change in [Na+] (P less than 0.056), and no changes were found in [Cl-]. Changes in venous acid-base status were analyzed quantitatively by applying relevant physicochemical theory. Altered values measured in the independent variables ([PTOT], PCO2, and net strong ion difference, [SID]) were used to calculate the corresponding changes in the dependent quantities. Comparison of individual measured and calculated values for the only one of these that is normally measured, ([H+]), yielded the theoretically expected agreement. PCO2 and [SID] changes accounted for most [H+] changes. These results demonstrate the usefulness of the quantitative approach (i.e., [H+]-PCO2 diagram) in the analysis and in understanding of plasma acid base changes with exercise and in clinical situations.

Effect of handlebar gripping on blood pressure during cycle ergometry.

The effects on SBP, DBP and HR of gripping the cycle ergometer handlebar during dynamic cycle ergometry were evaluated in 39 healthy males. Heart rate, SBP and DBP were measured at 150 Watt power load while gripping and not gripping the handlebar of a cycle ergometer. The sequence of gripping first or second was randomized. No differences in SBP, DBP or HR were shown under the two treatments. For submaximal cycle ergometry the influence of static handgrip on the handlebar does not seem to have a significant influence on SBP, DBP or HR response to dynamic exercise.

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Effect of exercise on salivary composition and cortisol in serum and saliva in man.

The effect of exercise on electrolytes and cortisol levels in serum and saliva was examined in 27 young, healthy male volunteers who performed graded submaximal cycle exercise for nine min at up to 85% of their age-predicted maximal heart rate. Seventeen men performed the Wingate anaerobic test for 30 s. A significant increase in pulse rate and systolic blood pressure and a decrease in diastolic blood pressure were found, and serum concentrations of Na+, K+, and lactate were significantly elevated immediately after exercise. A nonsignificant increase in saliva and serum cortisol levels was found. Significantly lowered salivary flow rate and elevated salivary K+, protein, and lactate concentrations were found within ten min after exercise. Salivary Mg2+ was significantly elevated after anaerobic exercise only.

Type A personality components and the blood pressure response to dynamic exercise.

One hundred and eleven healthy male subjects underwent cycle ergometry testing and completed a Jenkins type A personality survey. The subjects were divided into three equal groups with respect to their distribution on the Jenkins scales. The groups were compared for heart rate (HR), systolic blood pressure (SBP), the ratio of SBP/HR, and VO2 max/kg during rest and at exercise. Repeated measures MANOVA indicated that high scoring type A had lower HR values during exercise with no differences in SBP. However, the SBP/HR ratio was higher in the high type A group. The same was true for the component of hard-driving and competitiveness. Those scoring highest in this component also had higher VO2 max/kg body weight. From the description it could be conjectured that those with higher scores on type A components push themselves harder and thus achieve improvement in fitness. No clear explanation exists for the relative differences in SBP response.

Iron deficiency caused by 7 weeks of intensive physical exercise.

The present study was designed to evaluate the effect of an intensive physical training program involving both isometric and isotonic activities on the body iron status of 8 females and 11 males (age 20 +/- 1 year). The training was carried out over a 7 week period and included 8 h of varying physical activities each day. Venous blood samples were obtained from the subjects prior to the beginning of the training, on day 2 and in weeks 2, 4, 6 and 7 of the program. Blood samples were analyzed for iron, ferritin and hemoglobin (Hb) concentrations, total iron binding capacity (TIBC) and red blood cell count (RBC). Iron levels of males and females decreased 65% after 2 weeks of training (p less than 0.001). At the end of the training program 5 males and 6 females had lower than normal iron values (less than 13.4 mumol.l-1). TIBC increased 25% in women and 18% in men following 2 and 4 weeks of training (p less than 0.001) and remained at this elevated level throughout the training period. Ferritin levels decreased 50% in both sexes after 4 weeks of exercise (p less than 0.05) and remained at this level until the end of the training. Hb and RBC decreased 8-10% in both sexes during the training period. In two of the women anemia occurred after 4 weeks of training. The development of latent iron deficiency in a substantial number of participants after a relatively short period of training is uncommon and may reflect the high intensity of exercise required in this program.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood pressure response to dynamic exercise in healthy and hypertensive youths.

Recent evidence suggests that the blood pressure (BP) response to exercise may be useful in prediction of future hypertension. It has been shown that hypertensive youths have a higher systolic BP (SBP) response to exercise than their normotensive counterparts. Normotensive trained youths appear to have a higher BP response to exercise than untrained normotensive and in some instances hypertensive youths. While there is, at present, no clear explanation for this higher SBP response in trained youths, there is no evidence to suggest that these individuals are at increased risk of future health problems. Endurance-type conditioning is probably of benefit to hypertensive youths, and individuals with mild to moderate hypertension should not have restrictions of physical activity unless they show abnormalities during exercise testing. A lack of standardization in measuring and reporting SBP response to exercise exists. It is recommended that exercise BP measurement should be indirect, during upright exercise, recorded at more than one submaximal exercise level and at a steady state. The reference point for reporting BP should be the heart rate.

Exaggerated systolic blood pressure response to exercise in a water polo team.

Twenty-three top-level water polo players (WP) were examined for blood pressure (BP) response to graded and continuous cycle ergometry. Testing also included resting muscle biopsy for fiber typing, exercise ECG recording for heart rate (HR), exercise concentrations of blood lactate (LA), measured VO2max, and ratings of perceived exertion (RPE). A control group (C), whose subjects were physically active in endurance sports, but were older and less fit than the experimental subjects, was tested by an identical protocol. The BP response to exercise was significantly higher in the WP group at all comparison criteria including onset of blood lactate accumulation, absolute HR, percent of HRmax, and power loads (including loadless pedaling). To date, we are unaware of other reports on whole groups of sportsmen showing an exaggerated BP response to exercise. While it would appear from previous studies that normotensive individuals showing such a response are at a greater risk of developing hypertension, the significance of this BP response in highly-trained athletes in a specific sport remains unclear.

Follow-up of normotensive men with exaggerated blood pressure response to exercise.

The early detection of hypertension is of foremost concern. It may be that individuals who are normotensive at rest but who show an exaggerated blood pressure (BP) response to exercise are at greater risk of developing hypertension in the future. From exercise tests, a group (ER) of healthy young males who were normotensive at rest (BP less than or equal to 140/90) but showed an exaggerated BP response to exercise (systolic BP greater than or equal to 200 mm Hg and/or diastolic BP 10 mm Hg to greater than 90 mm Hg) were selected. A control group (NR) with exercise BP values less than these were matched for age, weight/height, skinfold thickness, resting BP less than or equal to 140/90, resting heart rate, aerobic fitness level, physical activity, smoking history, and family history of hypertension. After a follow-up period of 5.8 years (range 3 to 14 years) eight of the subjects from the ER group were found to be hypertensive, whereas none of the NR group were hypertensive. Stepwise multivariate regression showed the exercise blood pressure to be the best predictor of future blood pressure of the parameters reviewed in this study. Exaggerated BP response to exercise may serve as an additional risk marker for hypertension.

Hemoglobin, hematocrit, and calculated plasma volume changes induced by a short, supramaximal task.

The influence of a short, supramaximal task of 30 s duration on plasma volume (PV) was tested in 14 female physical education students. Hemoglobin (Hb), hematocrit (Hct), and osmolality (Osm) were tested pre- and post-exercise. Performance of the exercise test, consisting of 30 s all-out pedaling against a load of 4.4 J/kg body weight per pedal revolution, brought about a significant elevation in the measured variables. The changes in Hct, Hb, and Osm were 3.14%, 0.92g X dl-1, and 9.58 mOs/kg-1, respectively. The changes in PV, calculated from the increase in Hct alone and from changes in Hct and Hb, was found to be -10.4% and -11.2%, respectively. It is suggested that very short periods of maximal exercise can bring about some 10% - 15% drop in PV. Mechanisms for this decrease are not clear. It could result from changes in tissue osmolality, filtration pressure, or opening up of collapsed capillaries.

Differences between swimming and running as stimuli for exercise-induced asthma.

Thirteen children each exercised for 6 min by running on a treadmill and by tethered swimming, breathing air at room temperature and either 8% or 99% relative humidity continuously. Ventilation, gas exchange and heart rate were closely matched in all four tests in each child, with a mean oxygen consumption of 32.3 +/- 1.7 ml x min-1 x kg-1. The post-exercise fall in FEV1 expressed as a percentage of the baseline FEV1 (delta FEV1) was significantly greater after running compared with swimming breathing either humid or dry air. The delta FEV1 was also related to respiratory heat loss (RHL) calculated from measurements of inspired and expired gas temperature and humidity. At a standardised RHL, the difference between running and swimming was highly significant [delta FEV1 (%) +/- SE = 39 +/- 5 and 28 +/- 4 respectively, p less than 0.01]. These experiments suggest that the type of exercise influences the severity of exercise-induced asthma even under conditions of the same metabolic stress and respiratory heat loss.

Breathing dry or humid air and exercise-induced asthma during swimming.

Recent studies have shown the relevance of air humidity to the provocation of bronchoconstriction by running. The present study was undertaken to ascertain whether the humid air breathed during swimming could explain the protective effect of swimming on the asthmatic. Nine asthmatic children 9--15 years old swam while inspiring dry (15--35% R.H.) or humid (80--90% R.H.) air administered in a random order, a week separating the two sessions. The exercise challenge was an 8-min tethered swim at a metabolic rate (VO2) of 29 ml.kg-1.min-1, minute ventilation (VE) of 34 L.min-1, and a heart rate (HR) of 161 beats.min-1. Ambient air and water temperature were 28 +/- 2 degrees C and 27 +/- 2 degrees C, respectively. Pulmonary functions were tested pre and post swimming. Exercise VE, VO2 and HR were similar under the two conditions. No reduction in any of the pulmonary functions (FVC,FEV1.0,MMEFR,MBC) was found after 5 and 10 minutes following the swimming exercise in either of the conditions. In contrast, a treadmill run of similar metabolic and ventilatory intensity induced bronchoconstriction when room air was dried to 25--30% R.H. It is suggested that, unlike running, swimming is of low asthmogenicity even when inspired air is dried to 25--30% at neutral temperatures.