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PubMed1995

The stages of exercise scale and stages of exercise behavior in female adults.

Using the Transtheoretical Model of behavior change as a theoretical framework, a Stage of Exercise Scale (SOES) was developed. The ability of the SOES to differentiate between subjects classified into each of the theoretically posited stages was then studied in a sample of 178 female adults. Results showed that the scale was able to significantly and meaningfully differentiate between subjects classified by stage in terms of exercise energy expenditure (p < 0.0001, omega 2 = 0.18), physical activity energy expenditure (p < 0.0001, omega 2 = 0.15), and VO2peak ml/kg/min (p < 0.0001, omega 2 = 0.19). Stage-specific interventions have been successful when applied to other health behaviors and would appear to have promise for increasing our understanding of the exercise initiation and maintenance process. As such, researchers and practitioners may wish to use the SOES to begin testing the efficacy of stage-specific physical activity interventions.

Adult↗

PubMedDate not supplied

Electromyographic validation of basic exercises for physical conditioning programmes. I. Analysis of the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion) in rowing exercises with middle grip.

The electromyographic activity of the shoulder muscles Deltoid--anterior portion (DA) and Pectoralis major--clavicular portion (PMC) was tested on 24 male volunteers using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes during the execution of four different modalities of rowing exercises with middle grip. The results showed that rowing exercises are not appropriate for physical fitness programmes for PMC but some of them are significantly useful for DA. The authors present some suggestions to the use of the tested exercises.

Action Potentials↗

PubMed2026

Comparison of Traditional Chinese Exercise and Equipment-Based Exercise on Glycaemic Control and Vitamin D Levels in Middle-Aged and Elderly Patients With Prediabetes: A Randomised Controlled Trial.

BACKGROUND: Prediabetes is a critical window for preventing progression to type 2 diabetes mellitus (T2DM). Both vitamin D deficiency and physical inactivity are associated with impaired glucose metabolism. This study compared the effects of Traditional Chinese Exercise (TCE) and Kuanle Equipment Exercise (KEE) on glycaemic measures, lipid profiles, body composition and serum 25-hydroxyvitamin D3 [25(OH)D3] in middle-aged and elderly adults with prediabetes. METHODS: We conducted a 12-week, single-centre, randomised controlled trial involving 62 participants with prediabetes (mean age 55.2 ± 8.4 years; 88.7% female). Participants were randomly assigned to control (usual care, n = 21), TCE (n = 20), or KEE (n = 21). Primary outcomes included fasting plasma glucose (FPG), 2-h OGTT glucose, glycated haemoglobin (HbA1c) and serum 25(OH)D3. Secondary outcomes comprised triglycerides, total cholesterol, LDL-C, HDL-C and body composition. RESULTS: At baseline, mean serum 25(OH)D3 was 21.53 ± 3.90 nmol/L. At 12 weeks, both TCE and KEE improved FPG, 2-h OGTT glucose, HbA1c and 25(OH)D3 versus control (all p ≤ 0.001). Relative changes in FPG were -9.4% (TCE) and -15.2% (KEE) versus -1.5% (control); corresponding changes were -14.6% and -21.2% for 2-h OGTT glucose, -6.7% and -12.9% for HbA1c, and +60.6% and +81.9% for 25(OH)D3. Direct TCE-KEE comparisons were not significant (all p > 0.05). In an exploratory analysis, change in 25(OH)D3 was inversely associated with change in 2-h OGTT glucose (partial r = -0.358, p = 0.006), but not with FPG, HbA1c, or triglycerides. CONCLUSIONS: Both TCE and KEE improved glycaemic outcomes and increased serum 25(OH)D3 compared with usual care in middle-aged and elderly adults with prediabetes. Although KEE produced numerically larger estimates, direct between-group comparisons were not significant, and the superiority of KEE over TCE was not established. These vitamin D findings require confirmation in trials that quantify sunlight exposure and dietary vitamin D intake.

Aged↗

PubMedDate not supplied

Patients with dilated cardiomyopathy and less than 20% ejection fraction increase exercise capacity and have less severe arrhythmia after controlled exercise training.

The results of this pilot study suggest that patients with a diminished ejection fraction as low as 16% can safely perform an exercise program. A significant improvement in peak VO2 and maximal work rate was achieved. Moreover, this study suggests that exercise training might diminish the severity of asymptomatic ventricular arrhythmia; however a larger controlled study is needed to confirm these findings.

Arrhythmias, Cardiac↗

PubMed1982

Effect of long-term moderate physical exercise on plasma lipoproteins. The National Exercise and Heart Disease Project.

As part of the National Exercise and Heart Disease Project, 223 postcoronary men, aged 30 to 64, were randomly assigned to moderate exercise or control groups. Levels of total plasma cholesterol, high- and low-density lipoprotein (HDL and LDL) cholesterol, and triglycerides were measured. At baseline, alcohol intake, weight, and skin-fold thickness but not treadmill work capacity correlated with triglyceride or HDL cholesterol levels. After one year, no clinically important change in lipid levels was observed in either group. Using multiple regression analysis of the combined groups, changes in several independent variables, including work capacity change, were not predictive of changes in lipid levels. Thus, changes in levels of fitness and/or regular exercise did not substantially influence HDL cholesterol or other lipid levels.

Adult↗

PubMed2002

Cardiac output decline in prolonged dynamic exercise is affected by the exercise mode.

The aim of this study was to compare the cardiovascular responses to prolonged submaximal cycling and running. Eleven males [maximal oxygen uptake (VO(2max)): 3.58+/-0.15 l min(-1) for running and 3.84+/-0.16 l min(-1) for cycling; mean+/-SE] either cycled (C) or ran (R) for 90 min at 60% of mode-specific VO(2max), on two randomly assigned occasions. Cardiac output declined after 85 min of exercise in C (-1.9+/-0.5 l min(-1), P<0.01) but not in R, as a result of a more pronounced decrease in stroke volume in the former exercise mode (-22.7+/-3.8 ml beat(-1) vs -14.3+/-1.9 ml beat(-1), P<0.01) since heart rate did not differ between trials. Stroke volume responses were despite a higher level of dehydration (-3.3+/-0.2% in R vs -2.8+/-0.2% in C, P<0.05) and hyperthermia in R (39.6+/-0.1 vs 38.8+/-0.1 degrees C in C at 90 min, P<0.01). Finally, mean skin blood flow was lower in R than C (72+/-8 vs 89+/-10%; P<0.05). In conclusion, stroke volume and cardiac output decline was more pronounced in cycling than in running despite lower dehydration and rectal temperature in the former exercise mode.

Adult↗

PubMed1983

Predictors of dropout from cardiac exercise rehabilitation. Ontario Exercise-Heart Collaborative Study.

The Ontario Exercise-Heart Collaborative Study was a multicenter randomized clinical trial of high intensity exercise for the prevention of recurrent myocardial infarction in 733 men. Of the 678 subjects who could have participated for at least 3 years, 315 (46.5%) dropped out. Stepwise multiple linear logistic regression analysis was carried out to examine the relation between subject characteristics and the probability of dropping out during the study. Analysis was performed on the entry group as a whole by considering those subjects who had reinfarction while complying with the program and also by excluding all subjects with reinfarctions. The consistent and statistically significant predictors of dropout in both analyses were smoking and a blue collar occupation. Angina was significantly associated with dropout only when reinfarctions were excluded. It may be important to consider these factors when investigating the potential for compliance-improving strategies in reducing dropout from exercise rehabilitation programs.

Adult↗

PubMed2002

Evidence that brain glucose availability influences exercise-enhanced extracellular 5-HT level in hippocampus: a microdialysis study in exercising rats.

The relationship between brain glucose and serotonin is still unclear and no direct evidence of an action of brain glucose on serotonergic metabolism in central fatigue phenomena has been shown yet. In order to determine whether or not brain glucose could influence the brain 5-hydroxytryptamine (5-HT) system, we have monitored in microdialysis the effects of a direct injection of glucose in rat brain hippocampus on serotonergic metabolism [i.e. 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) and tryptophan (TRP)], during high intensive treadmill running. The injection was performed just before and after exercise. We have shown that glucose induced a decrease of brain 5-HT levels to a minimum of 73.0 +/- 3.5% of baseline after the first injection (P < 0.01) and to 68.5 +/- 5.5% of baseline after the second injection (P < 0.01) and consequently prevented the exercise-induced 5-HT enhanced levels. We have observed the same phenomenon concerning the 5-HIAA, but brain TRP levels were not decreased by the injections. In conclusion, this study demonstrates that brain glucose can act on serotonergic metabolism and thus can prevent exercise-induced increase of 5-HT levels. The results also suggest that extracellular brain glucose does not act on the synthesis way of 5-HT, but probably on the release/reuptake system.

Animals↗

PubMed2005

Is exercise-induced arterial hypoxemia in triathletes dependent on exercise modality?

To determine whether exercise modality affects arterial hypoxemia (EIAH) during training-intensity exercise, 13 triathletes performed 20 min of cycling (C) followed by 20 min of running (R): C-R, and two weeks later, 20 min of R followed by 20 min of C:R-C. Each trial was performed at an intensity slightly above the ventilatory threshold and close to the daily training intensity (75 % of VO2max). Ventilatory data were collected continuously using an automated breath-by-breath system. Partial pressure of oxygen in arterial blood (PaO2) was measured after each C and R segment and arterial oxyhemoglobin saturation (SpO2) was monitored continuously via pulse oximetry. The metabolic rate was similar across modalities and trials, i.e., C-R (53.8 +/- 3.8 vs. 51.1 +/- 5.3 ml.min(-1).kg(-1)) and R-C (52.2 +/- 4.5 vs. 53.2 +/- 4.6 ml.min(-1).kg (-1)). EIAH showed significantly greater severity for R compared to C irrespective of the order (p < 0.05 for both trials). R values of PaO2 (and SpO2) for C-R and R-C were 88.7 +/- 6.0 mm Hg (93.0 +/- 0.6 % SpO2) and 86.6 +/- 7.3 mm Hg (93.5 +/- 0.6 % SpO2) and C values were 93.7 +/- 8.4 mm Hg (95.4 +/- 0.4 % SpO2) and 91.4 +/- 5.4 mm Hg (94.8 +/- 0.3 % SpO2). R ventilatory data described a significantly different breathing pattern than C, with higher respiratory rate (35.9 b.min(-1) vs. 51.1 b.min(-1) for C-R, p < 0.01; and 50.0 b.min(-1) vs. 41.5 b.min(-1) for R-C, p < 0.01) and lower tidal volume (2636 ml vs. 2282 ml for C-R, p < 0.02 and 2272 ml vs. 2472 ml for R-C, p < 0.05). We concluded that EIAH was greater during running than cycling for a similar metabolic rate corresponding to training intensity and that EIAH could thus be considered dependent on exercise modality.

Adult↗

PubMed1983

Prior exhaustive exercise and subsequent, maximal constant load exercise performance.

The effect of an elevated blood lactate concentration on maximal constant load exercise performance (MCLE) was studied in nine males. Two experimental sessions followed a continuous VO2max test, each consisting of an initial work bout at approximately 110% VO2max, a 20 min recovery, and a second maximal performance test. Blood lactate concentrations reached approximately 10 mM following the initial work bout and were altered prior to the second bout by one of two recovery patterns: 1) active recovery (AR)--pedaling at 40% VO2max or 2) passive recovery (PR)--sitting quietly. Performance time, total pedal revolutions, metabolic parameters, and heart rate (HR) were measured during each work bout. Despite significant differences in blood lactate concentration, there were no differences in work output among the performance tests (either between conditions or from pre- to post-recovery); there was a low correlation (r = 0.08) between pre-existing blood lactate concentration and work output on a subsequent maximal constant load exercise test. It was concluded that elevated blood lactate concentration does not affect maximal constant load exercise performance.

Adult↗

PubMed1981

[Exercise-induced platelet aggregation: in vitro and ex-vivo aggregation of human platelets after administration of crystalline adrenaline and after ergometric exercise (author's transl)].

Even at an adrenaline concentration of 10(-9) mol/l, using strictly defined in-vitro flow conditions at 37 degrees C and physiological pH levels, there is a significant rise in platelet aggregation above control values (nine subjects, P lesser than 0.025). According to published reports, this concentration range is reached during physical exercise. Accordingly, there was also a rise in platelet number and spontaneous aggregation (P lesser than 0.01) in eleven healthy male subjects (average age 25, range 22-33, years) during ergometric exercise. These results and published reports indicate the potential danger of untrained elderly persons with vascular disease developing an increase in platelet aggregation during exercise.

Adult↗

PubMed2001

The acute phase response and exercise: the ultramarathon as prototype exercise.

OBJECTIVE: Controversy exists in relation to the nature of the acute phase response, which is known to occur following endurance exercise. This study was conducted to demonstrate the similarities between this response and the response consequent to general medical and surgical conditions. DESIGN: This is a case series field study of serum levels of acute phase reactants in a group of ultramarathon runners competing in a 6-day track race. PARTICIPANTS: Seven male and one female experienced ultramarathon runners. INTERVENTION: A track race of 6 days duration. MAIN OUTCOME MEASURES: Serum iron, ferritin, transferrin, albumin, haptoglobin, alpha-1 antitrypsin, complement components 3 and 4, C-reactive protein, and erythrocyte sedimentation rate, total iron binding capacity, and transferrin saturation. RESULTS: Of the 11 acute phase reactants measured, 6 (serum iron, ferritin, percent transferrin saturation, C-reactive protein, erythrocyte sedimentation rate, and haptoglobin) responded as if an acute phase response was present; 5 (tranferrin, albumin, alpha-1 antitrypsin, and complement components 3 and 4) did not respond in such a fashion. CONCLUSION: This study provides further evidence that the acute phase response consequent to exercise is analogous to that which occurs in general medical and surgical conditions. The previous demonstration of the presence of the appropriate cytokines following exercise, the findings of others in relation to acute phase reactants not the subjects of this study, the possibility that a training effect leading to attenuation of the response and the realization that the acute phase response is not identical across a range of medical conditions lends weight to the above conclusion.

Acute-Phase Proteins↗

PubMed1986

Thermogenesis with relation to exercise and exercise-training.

Exercise-training at environmental temperatures outside the thermal neutral zone, causes thermoregulatory adaptive reactions. In the heat, sweat efficiency is enhanced thus reducing the incidence of hyperthermia while in the cold discomfort and danger of frostbite are minimized by an improved cutaneous circulation specially in the extremities. Over long periods of time exercise does not affect thermogenesis except when refeeding. It is suggested that the reduced postprandial heat production reported in exercise-trained subjects is related to changes in nutrient metabolism which in turn could be related to insulin and norepinephrine modified actions.

Body Temperature Regulation↗

PubMed1984

Effect of exercise training on plasma catecholamines and haemodynamics of adolescent hypertensives during rest, submaximal exercise and orthostatic stress.

Twelve adolescents with essential hypertension were studied to determine the effect of exercise training on plasma catecholamine concentrations, blood pressure and cardiovascular haemodynamics at rest and during submaximal exercise and orthostatic stress. Maximal oxygen consumption (VO2max) increased 13% with training while body weight and body fat did not change. Resting systolic and diastolic blood pressures decreased significantly with training, while plasma norepinephrine and epinephrine levels were unchanged. The increase in systolic blood pressure in response to standing was significantly lower after training, while the plasma catecholamine response was not significantly different. At the same absolute work rate after training, the subjects' systolic and diastolic blood pressures, heart rates, and plasma norepinephrine and epinephrine levels were significantly lower than before training. At the same relative work rate after training, the blood pressure response was the same as before training despite significantly higher plasma norepinephrine levels. Thus, the training-induced changes in resting blood pressures and blood pressure responses to orthostatic and submaximal exercise stress cannot be attributed to decreases in plasma catecholamine levels.

Adaptation, Physiological↗

PubMed1976

Cardiac monitoring during exercise tests in the horse. 3. Changes in the electrocardiogram during and after exercise.

Changes that occur in the equine ECG during and after exercise have been described and compared with resting ECG's obtained from the same horses. When the speed of work equals or is greater than "three-quarter pace" (i.e. "even time" or 200 metres in 15 seconds) the high heart rates developed cause the loss of ECG waveforms that are readily discernible at rest. Although differences in the waveforms between horses with normal and abnormal resting ECG's have been observed, the more definitive useful information is the fact that abnormal horses showed significantly higher heart rates than normal horses at a particular speed of work. When this occurs in combination with a resting ECG classified as borderline or abnormal and the exercise ECG shows positive, low amplitude, broad rounded T waves or transient bursts of sine-waves suggestive of ventricular flutter, racing performance is likely to be impaired. Although more work needs to be done and improvements in technology are necessary, the exercise ECG has potential for improving understanding of physical fitness and the significance of resting cardiac abnormalities.

Animals↗

PubMed1995

Determinants of maximal exercise VO2 during single leg knee-extensor exercise in humans.

Previously, a reduction in fractional inspired O2 (FIO2) during dynamic exercise of the human quadriceps muscles of one leg resulted in increased muscle blood flow (Q) and a fall in femoral venous O2 tension (PO2) but no change in peak O2 uptake (VO2). These data can be interpreted as reflecting an increase in muscle O2 diffusive capacity (DO2) in hypoxia or, alternatively, that maximum O2 uptake (VO2max) was not reached for these muscles when air was breathed, in which case the theory of diffusion limitation to VO2max is not applicable to these data. Therefore, the primary goal of this study was to test the hypothesis that VO2max would be reduced in hypoxia as a result of the decreased O2 supply and a constant diffusional conductance from blood to exercising muscle. To resolve this, five trained men were studied performing single leg incremental knee-extensor exercise to VO2max while breathing air (N) and again while breathing 12% O2 (H). The maximum work rate (WRmax) was 30-50 W greater and produced even greater associated maximum leg Q (N = 9.1 +/- 0.61 and H = 8.2 +/- 0.65 l/min, P < 0.05) and leg O2 than in previous studies. Hypoxia reduced quadriceps muscle VO2max (N = 1.4 +/- 0.1 and H = 1.1 +/- 0.1 l/min, P < 0.05). In the two conditions the relationships between 1) measured femoral venous PO2 (N = 18 +/- 0.5 and H = 13 +/- 0.5 Torr) and VO2max and 2) calculated mean capillary PO2 (N = 37 +/- 0.4 and H = 28 +/- 0.8 Torr) and VO2max were each one of proportionality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Independence of exercise hyperpnea and acidosis during high-intensity exercise in ponies.

We investigated arterial PCO2 (PaCO2) and pH (pHa) responses in ponies during 6-min periods of high-intensity treadmill exercise. Seven normal, seven carotid body-denervated (2 wk-4 yr) (CBD), and five chronic (1-2 yr) lung (hilar nerve)-denervated (HND) ponies were studied during three levels of constant load exercise (7 mph-11%, 7 mph-16%, and 7 mph-22% grade). Mean pHa for each group of ponies became alkaline in the first 60 s (between 7.45 and 7.52) (P less than 0.05) at all work loads. At 6 min pHa was at or above rest at 7 mph-11%, moderately acidic at 7 mph-16% (7.32-7.35), and markedly acidic at 7 mph-22% (7.20-7.27) for all groups of ponies. Yet with no arterial acidosis at 7 mph 11%, normal ponies decreased PaCO2 below rest (delta PaCO2) by 5.9 Torr at 90 s and 7.8 Torr by 6 min of exercise (P less than 0.05). With a progressively more acid pHa at the two higher work loads in normal ponies, delta PaCO2 was 7.3 and 7.8 Torr by 90 s and 9.9 and 11.4 Torr by 6 min, respectively (P less than 0.05). CBD ponies became more hypocapnic than the normal group at 90 s (P less than 0.01) and tended to have greater delta PaCO2 at 6 min. The delta PaCO2 responses in normal and HND ponies were not significantly different (P greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗

PubMed2003

Effects of exercise training on acclimatization to hypoxia: systemic O2 transport during maximal exercise.

Acclimatization to hypoxia has minimal effect on maximal O2 uptake (Vo2 max). Prolonged hypoxia shows reductions in cardiac output (Q), maximal heart rate (HR-max), myocardial beta-adrenoceptor (beta-AR) density, and chronotropic response to isoproterenol. This study tested the hypothesis that exercise training (ET), which attenuates beta-AR downregulation, would increase HRmax and Q of acclimatization and result in higher Vo2 max. After 3 wk of ET, rats lived at an inspired Po2 of 70 Torr for 10 days (acclimatized trained rats) or remained in normoxia, while both groups continued to train in normoxia. Controls were sedentary acclimatized and nonacclimatized rats. All rats exercised maximally in normoxia and hypoxia (inspired Po2 of 70 Torr). Myocardial beta-AR density and the chronotropic response to isoproterenol were reduced, and myocardial cholinergic receptor density was increased after acclimatization; all of these receptor changes were reversed by ET. Normoxic Vo2 max (in ml.min-1.kg-1) was 95.8 +/- 1.0 in acclimatized trained (n = 6), 87.7 +/- 1.7 in nonacclimatized trained (P < 0.05, n = 6), 74.2 +/- 1.4 in acclimatized sedentary (n = 6, P < 0.05), and 72.5 +/- 1.2 in nonacclimatized sedentary (n = 8; P > 0.05 acclimatized sedentary vs. nonacclimatized sedentary). A similar distribution of Vo2 max values occurred in hypoxic exercise. Q was highest in trained acclimatized and nonacclimatized, intermediate in nonacclimatized sedentary, and lowest in acclimatized sedentary groups. ET preserved Q in acclimatized rats thanks to maintenance of HRmax as well as of maximal stroke volume. Q preservation, coupled with a higher arterial O2 content, resulted in the acclimatized trained rats having the highest convective O2 transport and Vo2 max. These results show that ET attenuates beta-AR downregulation and preserves Q and Vo2 max after acclimatization, and support the idea that beta-AR downregulation partially contributes to the limitation of Vo2 max after acclimatization in rats.

Acclimatization↗