SEARCH · PubMed Health

Results for “Exercise”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,675 records · Page 93Linked to original sources

PubMed2005

Aerobic exercise interventions for adults living with HIV/AIDS.

BACKGROUND: The profile of HIV infection is constantly changing. Although once viewed as an illness progressing to death, among those with access to antiretroviral therapy, HIV can now present as a disease with an uncertain natural history, perhaps a chronic manageable disease for some. This increased chronicity of HIV infection has been mirrored by increased prevalence of disablement in the HIV-infected population (Rusch 2004). Thus, the needs of these individuals have increasingly included the management of impairments (problems with body function or structure as a significant deviation or loss, such as pain or weakness), activity limitations (difficulties an individual may have in executing activities, such as inability to walk) and participation restrictions (problems an individual may experiences in involvement in life situations, such as inability to work) (WHO 2001). Exercise is a key strategy employed by people living with HIV/AIDS and by rehabilitation professionals to address these issues. Exercise has been shown to improve strength, cardiovascular function and psychological status in seronegative populations (Bouchard 1993), but what are the effects of exercise for adults living with HIV? If the risks and benefits of exercise for people living with HIV are better understood, appropriate exercise may be undertaken by those living with HIV/AIDS and appropriate exercise prescription may be practiced by healthcare providers. If effective and safe, exercise may enhance the effectiveness of HIV management, thus improving the overall outcome for adults living with HIV. OBJECTIVES: To examine the safety and effectiveness of aerobic exercise interventions on immunological/virological, cardiopulmonary and psychological parameters in adults living with HIV/AIDS. SEARCH STRATEGY: To identify the appropriate studies, we conducted a search using MEDLINE, EMBASE, SCIENCE CITATION INDEX, AIDSLINE, CINAHL, HEALTHSTAR, PSYCHLIT, SOCIOFILE, SCI, SSCI, ERIC and DAI. We also reviewed both published and unpublished abstracts and proceedings from major international and national HIV/AIDS conferences such as the Intersciences Conference on Antimicrobial Agents and Chemotherapy (ICAAC), the Conference on Retroviruses and Opportunistic Infections (CROI), the Infectious Diseases Society of America Conference (IDSA) and the International AIDS Conference (IAC). Reference lists from pertinent articles and books were reviewed and personal contacts with authors were used, as well as Collaborative Review Group databases. Targeted journals were handsearched for relevant articles. There were no language restrictions. Searches for the original review covered the period from 1980 to July 1999. The first update of this review included an additional search of the literature, followed by identification of included studies that met the inclusion criteria from August 1999 to January 2001. For the second update, we conducted a search to identify additional studies published from February 2001 to August 2003. SELECTION CRITERIA: Studies were included if they were randomized controlled trials (RCTs) comparing aerobic exercise interventions with no aerobic exercise interventions or another exercise or treatment modality, performed at least three times per week for at least four weeks among adults (18 years of age or older) living with HIV/AIDS. DATA COLLECTION AND ANALYSIS: Data on study design, participants, interventions, outcomes and methodological quality were abstracted from studies that met the inclusion criteria onto specifically designed data collection forms by at least two reviewers. Meta-analysis was conducted using RevMan 4.2 computer software on outcomes whenever possible. MAIN RESULTS: A total of 10 studies (six from the original search, two from the first updated search and two from this second updated search) met the inclusion criteria for this review. Main results indicated that performing constant or interval aerobic exercise, or a combination of constant aerobic exercise and progressive resistive exercise for at least 20 minutes, at least three times per week for four weeks appears to be safe and may lead to significant reductions in depressive symptoms and potentially clinically important improvements in cardiopulmonary fitness. These findings are limited to those participants who continued to exercise and for whom there was adequate follow-up data. AUTHORS' CONCLUSIONS: Aerobic exercise appears to be safe and may be beneficial for adults living with HIV/AIDS. These findings are limited by the small sample sizes and large withdrawal rates of the included studies. Future research would benefit from an increased attention to participant follow-up and intention-to-treat analysis. Further research is required to determine the optimal parameters of aerobic exercise and stage of disease in which aerobic exercise may be most beneficial for adults living with HIV.

Adult↗

PubMed2003

Exercise therapy for patellofemoral pain syndrome.

BACKGROUND: Patellofemoral pain syndrome (PFPS) is a common problem among adolescents and young adults, characterised by retropatellar pain (behind the kneecap) or peripatellar pain (around the kneecap) when ascending or descending stairs, squatting or sitting with flexed knees. Etiology, structures causing the pain and treatment methods are all debated in literature, but consensus has not been reached so far. Exercise therapy to strengthen the quadriceps is often prescribed, though its efficacy is still debated. OBJECTIVES: This review aims to summarise the evidence of effectiveness of exercise therapy in reducing anterior knee pain and improving knee function in patients with PFPS. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group and Cochrane Rehabilitation and Related Therapies Field specialised registers, the Cochrane Controlled Trials Register, PEDro - The Physiotherapy Evidence Database, MEDLINE, EMBASE, CINAHL, up till December 2001 for controlled trials (randomised or not) comparing exercise therapy with control groups, or comparing different types of exercise therapy. SELECTION CRITERIA: Only trials focusing on exercise therapy in patients with PFPS were considered. Trials in patients with other diagnoses such as tendinitis, Osgood Schlatter syndrome, bursitis, traumatic injuries, osteoarthritis, plica syndrome, Sinding-Larssen-Johansson syndrome and patellar luxations were excluded. DATA COLLECTION AND ANALYSIS: From 750 publications 12 trials were selected. All included trials studied quadriceps strengthening exercises. Outcome assessments for knee pain and knee function in daily life were used in a best evidence synthesis to summarise evidence for effectiveness. MAIN RESULTS: One high and two low quality studies used a control group not receiving exercise therapy. Significantly greater pain reduction in the exercise groups was found in one high and one low quality study, though at different time points. Only one low quality study reported significantly greater functional improvement with exercise. Five studies compared exercise therapies that could be designated closed kinetic chain exercise (foot in contact with a surface) versus open kinetic chain exercise (foot not in contact with a surface). Two of these studies were of high quality, but no significant differences in improvement of function or reduction of pain were apparent between the types of exercise in any of the studies. The remaining four studies, all of which were of low quality, focused on other treatment comparisons. REVIEWER'S CONCLUSIONS: The evidence that exercise therapy is more effective in treating PFPS than no exercise was limited with respect to pain reduction, and conflicting with respect to functional improvement. There is strong evidence that open and closed kinetic chain exercise are equally effective. Further research to substantiate the efficacy of exercise treatment compared to a non-exercising control group is needed, and thorough consideration should be given to methodological aspects of study design and reporting.

Adolescent↗

PubMed1995

Influence of left ventricular hypertrophy on detection of coronary artery disease using exercise echocardiography.

OBJECTIVES: This study examined the influence of left ventricular hypertrophy on the accuracy of exercise electrocardiography and echocardiography for detection of coronary artery disease. BACKGROUND: Electrocardiographic repolarization abnormalities caused by left ventricular hypertrophy compromise the diagnostic accuracy of exercise electrocardiography but not of exercise echocardiography. The relative merits of these investigations are less well defined in patients with hypertrophy but without electrocardiographic (ECG) changes. METHODS: We prospectively evaluated 147 consecutive patients without prior myocardial infarction undergoing both exercise echocardiography and coronary arteriography. Coronary stenoses > 50% diameter were present in 62 patients (42%). Positive test results were defined by a new or worsening wall motion abnormality or > 0.1 mV of ST depression. Echocardiographic left ventricular hypertrophy (mass > 131 g/m2 in men, > 100 g/m2 in women) was identified in 68 patients. A subgroup with clinically suspected hypertrophy was defined according to the presence of ECG evidence of hypertrophy, hypertension or aortic stenosis. RESULTS: The overall sensitivity of exercise echocardiography exceeded that of exercise electrocardiography (71% vs. 54%, p = 0.06). Echocardiographic hypertrophy had no significant effect on the sensitivity of either test. The specificity of exercise echocardiography exceeded that of exercise electrocardiography (91 vs. 74%, p = 0.01). In patients with hypertrophy, the specificity of exercise echocardiography exceeded that of exercise electrocardiography (95% vs. 69%, p < 0.01), whereas among patients without hypertrophy, the specificities (respectively, 87% and 78%) were more comparable. The accuracy of exercise echocardiography exceeded that of the exercise ECG in the overall group (82% vs. 65%, p = 0.002) and in patients with hypertrophy (85% vs. 60%, p = 0.004), but this difference was less prominent in patients without hypertrophy (80% vs. 69%, p = NS). In patients with clinically suspected hypertrophy, exercise echocardiography demonstrated a higher sensitivity, specificity and accuracy than exercise electrocardiography. The cost incurred in the identification of coronary disease was least with a strategy involving use of the exercise echocardiogram instead of routine exercise testing in patients with known or clinically suspected left ventricular hypertrophy. CONCLUSIONS: Exercise echocardiography is more accurate than exercise electrocardiography for the detection of coronary artery disease in patients with known or clinically suspected left ventricular hypertrophy.

Adult↗

PubMedDate not supplied

Exercise discussions during cancer treatment consultations.

PURPOSE: Physical exercise has been shown to help cancer survivors cope with treatment side effects. The purpose of this study was to examine the role of the oncologist in promoting exercise in cancer survivors. DESCRIPTION OF STUDY: Cancer survivors who had recently completed treatment (N = 311) were mailed a self-administered questionnaire that assessed the following: whether exercise was discussed during any of their treatment consultations; whether they preferred that exercise be discussed during this time; their perceived oncologist approval for exercise; and the amount of exercise they performed during treatment. RESULTS: Descriptive statistics showed that 28.4% of cancer survivors reported that their oncologist initiated a discussion of exercise during their treatment consultation, that 13.9% said that they initiated a discussion, and that 57.8% said that exercise was not discussed. Survivors younger than 60 years of age were more likely to initiate a discussion of exercise than were older survivors. Survivors whose oncologist initiated a discussion of exercise also reported a stronger normative belief for exercise, performing more frequent exercise during treatment, and performing more total minutes of exercise during treatment. Most (82.2%) survivors preferred that the oncologist initiate the discussion of exercise. CLINICAL IMPLICATIONS: These findings indicate that most cancer survivors responding to this survey preferred that their oncologist initiate a discussion of exercise. Such a discussion appears to increase survivor exercise levels during treatment. If confirmed in a prospective, randomized, controlled trial, the implication is that an oncologist-initiated discussion of exercise during treatment consultations may be a cost-effective strategy for promoting exercise in cancer survivors.

Adult↗

PubMed1991

Effects of digoxin, propranolol, and verapamil on exercise in patients with chronic isolated atrial fibrillation.

STUDY OBJECTIVE: The aim was to evaluate the effects of digoxin, propranolol, and verapamil on exercise in patients with chronic isolated atrial fibrillation. DESIGN: Patients with chronic isolated atrial fibrillation underwent maximal exercise testing before and after the administration of digoxin, propranolol, or verapamil. Heart rate, oxygen uptake and oxygen pulse were observed at rest, at gas exchange anaerobic threshold, and at peak exercise. SUBJECTS: The subjects were 10 patients (aged 48-78 years, mean age 60, SD 9, years) with chronic isolated atrial fibrillation. MEASUREMENTS AND MAIN RESULTS: During exercise without medication, the heart rate was 85 (SD 8) beats.min-1 at rest, 127(19) at the level of anaerobic threshold, and 175(17) at peak exercise. With digoxin, heart rate was reduced to 75(9) beats.min-1 at rest (control v digoxin, p less than 0.01). However, reduction of heart rate was not seen at anaerobic threshold or at peak exercise. With propranolol, heart rate was 63(7) beats.min-1 at rest, 99(16) at anaerobic threshold, and 138(28) at peak exercise (control v propranolol, all p less than 0.01). Heart rate with verapamil was 70(13) beats.min-1 at rest, 107(30) at anaerobic threshold, and 138(28) at peak exercise (control v verapamil, p less than 0.05 at rest and at anaerobic threshold, p less than 0.01 at peak exercise. Neither digoxin, nor propranolol, nor verapamil changed the oxygen uptake during exercise. Without medication, oxygen pulse was 6.5(2.0) ml.beat-1 at anaerobic threshold and 7.7(2.1) ml.beat-1 at peak exercise. With digoxin, the change of oxygen pulse, versus without medication, was not significant at rest or at anaerobic threshold but was increased at peak exercise, at 8.3(2.1) v 7.7(2.1) ml.beat-1, p less than 0.05. With propranolol, oxygen pulse was increased to 8.2(1.9) ml.beat-1 at anaerobic threshold and 9.2(2.3) ml.beat-1 at peak exercise (control v propranolol, both p less than 0.01). With verapamil, oxygen pulse was increased to 8.7(1.8) ml.beat-1 at anaerobic threshold and 10.0(2.1) ml.beat-1 at peak exercise (control v verapamil, both p less than 0.01). CONCLUSIONS: Digoxin was effective in reducing heart rate at rest, but failed to reduce it during exercise. Propranolol and verapamil reduced heart rate at all levels of exercise as well as at rest. Oxygen uptake during exercise (total exercise capacity) was not reduced with propranolol or verapamil; this was thought to have been accomplished by an increased oxygen pulse.

Aged↗

PubMed2006

Why should we exercise when our knees hurt? A qualitative study of primary care patients with osteoarthritis of the knee.

BACKGROUND: Osteoarthritis (OA) of the knee is common and disabling. Exercise is effective in reducing pain and disability, but long-term adherence to exercise regimens is disappointing, and motivation to exercise in those with OA knee is poorly understood. OBJECTIVES: To examine the views of primary care patients with OA knee towards exercise, explore factors that determine the acceptability and motivation to exercise, and to identify barriers that limit its use. METHOD: Semi-structured interviews were conducted with 22 primary care patients with OA knee, six of whom also participated in a focus group for triangulation. Transcripts were coded into categories and themes to develop a conceptual framework and typology of exercise behaviour. RESULTS: Exercise behaviour depended upon physical capacity to exercise; exercise beliefs and other factors such as enjoyment, social support, priority setting and context. Four types of patients were identified: 'long-term sedentary' who had never exercised; 'long-term active' who continued to exercise; 'exercise retired' who used to exercise, but had stopped because of their symptoms, and because they believed that exercise was damaging their joints; and 'exercise converted' who recently started to exercise, and preferred a gym because of the supervision and social support they received there. CONCLUSIONS: Several physical, cognitive and contextual factors, and a typology of exercise behaviour were identified that could be addressed in primary care consultations. The importance of gyms and GP referral schemes for people who are exercising for the first time, and the high level of patient satisfaction associated with these were highlighted.

Aged↗

PubMed2002

Exercise capacity and brain natruiretic peptide in hypertension.

Brain natriuretic peptide (BNP) is increased and it is also released during exercise in hypertension, but its biologic role is unclear. However, since BNP is released from the left ventricule and it is known to reduce left ventricular filling pressure, it is possible that it exerts a favorable effect on exercise performance. We studied the relationship between endogenous BNP release and exercise capacity in hypertension with reference to left ventricular hypertrophy (LVH). Cardiopulmonary exercise study was carried out in 2 groups of hypertensives, 24 [16 men, aged 50 (SD 11) years] of whom had echocardiographic LVH and 25 [16 men, aged 41 ( 12)] who did not have LVH. In multiple regression analyses, the major determinants of peak oxygen uptake (VO max) were age (-), sex (male), peak exercise systolic BP (+) and post-exercise BNP (-). For the predicted adjusted %VO max as a measure of individualised exercise capacity, the significant predictors were the exercise-induced BNP rise (-) (p = 0.0003) and peak exercise systolic BP (+) (p = 0.001). In other words, subjects with greater myocardial dysfunction had a greater rise in BNP during exercise. LVH did not however relate to exercise capacity. The baseline, post-exercise and the % rise in BNP (pmol/L) with exercise were not statistically different in those with LVH compared with those without (median values of 11.2, 14.6 and 133% versus 10.6, 11.5 and 120% respectively). Similarly, there were no significant differences in exercise capacity between the groups: exercise time, oxygen uptakes at ventilatory threshold and at peak exercise (VO max) were 10.8 (2.5) min, 15.8 (4.6) and 33.6 (7.6) ml/min/kg in the LVH group against 11.4 (2.9) min, 18.6 (5.2) and 36 (11.1) ml/min/kg in the non-LVH group respectively. The estimated VO max was not different from that predicted from age, sex, weight and height in either group suggesting preserved exercise capacity in these subjects as a whole. In Conclusion, BNP may potentially act as a homeostatic mechanism that helps to limit exercise incapacity in hypertension irrespective of LVH.

Adult↗

PubMed2002

Impact of a transtheoretical model on the psychosocial factors affecting exercise among workers.

The purpose of this study was to investigate the effects of exercise intervention on improvement of perceived exercise benefit, perceived exercise barrier, and exercise self-efficacy. A quasi- experimental design was utilized and purposive sampling was conducted at a telecom worksite in southern Taiwan. One hundred and ninety-three subjects were assigned to an experimental and a control group. The experimental group, which consisted of 133 subjects, participated in a program of exercise intervention. The intervention program applied a transtheoretical model to aid subjects in developing effective approaches within different stages of the exercise change. It included written materials and teaching activities for the different stages of exercise. The control group, which consisted of 60 subjects, had no treatment. All subjects completed a structured questionnaire, including perceived exercise benefits, perceived exercise barriers, exercise self-efficacy, and stages of exercise, pre-test and post-test. Statistical analyses included Chi-square test, paired t-test, analysis of covariance, one-way ANOVA, and Scheffe's post hoc comparison. After the exercise intervention, the results post-test of the experimental group showed that (1) perceived exercise benefit, perceived exercise barriers, and exercise self-efficacy improved significantly, and (2) perceived exercise benefit and exercise self-efficacy were significantly higher than those of the control group post-test while perceived exercise barriers were significantly lower than those of the control group post-test.

Adult↗

PubMed1997

Sprint training enhances ionic regulation during intense exercise in men.

1. This study investigated the effects of 7 weeks of sprint training on changes in electrolyte concentrations and acid-base status in arterial and femoral venous blood, during and following maximal exercise for 30 s on an isokinetic cycle ergometer. 2. Six healthy males performed maximal exercise, before and after training. Blood samples were drawn simultaneously from brachial arterial and femoral venous catheters, at rest, during the final 10 s of exercise and during 10 min of recovery, and analysed for whole blood and plasma ions and acid-base variables. 3. Maximal exercise performance was enhanced after training, with a 13% increase in total work output and a 14% less decline in power output during maximal cycling. 4. The acute changes in plasma volume, ions and acid-base variables during maximal exercise were similar to previous observations. Sprint training did not influence the decline in plasma volume during or following maximal exercise. After training, maximal exercise was accompanied by lower arterial and femoral venous plasma [K+] and [Na+] across all measurement times (P < 0.05). Arterial plasma lactate concentration ([Lac-]) was greater (P < 0.05), but femoral venous plasma [Lac-] was unchanged by training. 5. Net release into, or uptake of ions from plasma passing through the exercising muscle was assessed by arteriovenous concentration differences, corrected for fluid movements. K+ release into plasma during exercise, and a small net K+ uptake from plasma 1 min post-exercise (P < 0.05), were unchanged by training. A net Na+ loss from plasma during exercise (P < 0.05) tended to be reduced after training (P < 0.06). Release of Lac- into plasma during and after exercise (P < 0.05) was unchanged by training. 6. Arterial and venous plasma strong ion difference ([SID]; [SID] = [Na+] + [K+] - [Lac-] - [Cl-]) were lower after training (mean differences) by 2.7 and 1.8 mmol l-1, respectively (P < 0.05). Arterial and femoral venous CO2 tensions and arterial plasma [HCO3-] were lower after training (mean differences) by 1.7 mmHg, 4.5 mmHg and 1.2 mmol l-1, respectively (P < 0.05), with arterial plasma [H+] being greater after training by 2.2 nmol l-1 (P < 0.05). 7. The acute changes in whole blood volume and ion concentrations during maximal exercise were similar to previous observations: Arterial and femoral whole blood [K+] and [Cl-] were increased, whilst [Na+] was lower, across all observation times after training (P < 0.05). 8. Net uptake or release of ions by exercising muscle was assessed by arteriovenous whole blood concentration differences, corrected for fluid movements. A net K+ uptake by muscle occurred at all times, including exercise, but this was not significantly different after training. An increased net Na+ uptake by muscle occurred during exercise (P < 0.05) with greater Na+ uptake after training (P < 0.05). Net muscle Lac- release and Cl- uptake occurred at all times (P < 0.05) and were unchanged by training. 9. Sprint training improved muscle ion regulation, associated with increased intense exercise performance, at the expense of a greater systemic acidosis. Increased muscle Na+ and K+ uptake by muscle during the final seconds of exercise after training are consistent with a greater activation of the muscle Na(+) - K+ pump, reduced cellular K+ loss and the observed lesser rate of fatigue. The greater plasma acidosis found after sprint training was caused by a lower arterial plasma [SID] due to lower plasma [K+] and [Na+], and higher plasma [Lac-].

Acid-Base Equilibrium↗

PubMed1993

Doppler echocardiographic assessment of the hemodynamic benefits of rate adaptive AV delay during exercise in paced patients with complete heart block.

To determine if rate adaptation of the atrioventricular (AV) delay (i.e., linearly decreasing the AV interval for increasing sinus rate) improves exercise left ventricular systolic hemodynamics, we performed paired maximal semi-upright bicycle exercise tests (EXTs) on 14 chronotropically competent patients with dual chamber pacemakers. Nine patients with complete AV block (CAVB) and total ventricular pacing dependence during exercise comprised the experimental group. Pacemakers in these patients were programmed randomly to rate adaptive AV delay (AVDR) for one EXT and fixed AV delay (AVDF) for the other EXT. AVDF was 156 msec; AVDR decreased linearly from 156-63 msec from rates of 78-142 beats/min. The other five patients had intact AV conduction and comprised the control group who were exercised in identical fashion while their pacemakers were inhibited throughout exercise to assure reproducibility of hemodynamic measurements between EXTs. Cardiac hemodynamics were calculated using measured Doppler echocardiographic systolic aortic valve flows recorded suprasternally with an independent 2-MHz Doppler transducer during a graded ramp exercise protocol. For analysis, exercise was divided into four phases to compare Doppler measurements at submaximal and maximal levels of exercise: rest, early exercise (1st stage), late exercise (stage preceding peak), and peak. Patients achieved statistically similar heart rates between EXTs at each phase of exercise. Although at lower levels of exercise cardiac hemodynamics did not differ, experimental patients (with CAVB) showed a statistically significant benefit to cardiac output at peak exercise with heart rates of 129 +/- 13 beats/min (AVDR: 9.4 +/- 2.8 L/min; AVDF: 8.2 +/- 2.6 L/min, P = 0.002), stroke volume (AVDR: 74.1 +/- 25.6 mL; AVDF: 64.3 +/- 24.4 mL, P = 0.0003), and aortic ejection time (AVDR: 253.3 +/- 35.7 msec; AVDF: 226.7 +/- 35.0 msec, P = 0.002). Duration of exercise, peak rate pressure product, peak aortic flow velocities, and acceleration times did not differ. In contrast, control group patients (intact AV conduction throughout exercise) showed no statistical differences between any hemodynamic parameters measured at any phase of exercise from the first to second exercise test. These data demonstrate that systolic cardiac hemodynamics measured echocardiographically at the high heart rates achieved with peak exercise are improved with AVDR compared to AVDF in chronotropically competent patients with complete AV block. This is due primarily to improved stroke volume and a longer systolic ejection time with AV delay rate adaptation.

Adult↗

PubMed1996

Effects of an exercise program on musculoskeletal symptoms and physical capacity among nursing staff.

Musculoskeletal disorders are a major health problem, and nursing staff are often seen as a risk group. The purpose of this study was to evaluate the effect of a weekly exercise program among nursing staff on musculoskeletal symptoms and to study the relation to changes in physical capacity. A total of 106 nurses and nursing aides from four geriatric wards were invited to participate; 86 accepted. A cross-over design was used. The staff from two wards were assigned to an exercise period and the staff from the other wards to a control period for the first intervention period. After a wash-out period, the intervention changed. For the exercise periods the staff were invited to participate in an exercise program twice a week for 8 weeks. In total 50 subjects participated more than 8 times regularly during the exercise periods (participants = > or = 8 times regular participation, nonparticipants = < 8). During the control periods 78 subjects attended without intervention. Assessments were made with a standardized questionnaire for analysis of musculoskeletal and psychosomatic symptoms, testing of muscle strength in m. quadriceps with a Cybex dynamometer, and testing of cardiovascular capacity with a Dynavite computerized exercise bicycle before and after the exercise periods. The muscle strength in m. quadriceps increased more during the exercise periods compared with the control periods, explained primarily by the subgroup of nonregular exercisers and those > or = 40 years of age. The number of musculoskeletal symptoms tended to decrease more in the subgroup of nonregular exercisers (those who exercised less than once a week in their spare time) during the exercise periods compared with the nonregular exercisers during the control periods. Comparisons within groups showed a decrease in the number of musculoskeletal symptoms within the exercise periods, explained primarily by a decrease among the participants rather than among the nonparticipants. The decrease within the participants was explained primarily by the subgroup of nonregular exercisers and those > or = 40 years of age. An increase in cardiovascular capacity and a tendency to increase in muscle strength in m. quadriceps were seen among the participants, explained primarily by the effect in the subgroup of nonregular exercisers. The study suggests that a moderate weekly exercise program, performed in a group, among nursing staff affects physical capacity and the number of musculoskeletal symptoms for subjects who are nonregular exercisers and probably subjects > or = 40 years of age.

Adult↗

PubMed2003

Exercise elicits phase shifts and acute alterations of melatonin that vary with circadian phase.

To examine the immediate phase-shifting effects of high-intensity exercise of a practical duration (1 h) on human circadian phase, five groups of healthy men 20-30 yr of age participated in studies involving no exercise or exposure to morning, afternoon, evening, or nocturnal exercise. Except during scheduled sleep/dark and exercise periods, subjects remained under modified constant routine conditions allowing a sleep period and including constant posture, knowledge of clock time, and exposure to dim light intensities averaging (+/-SD) 42 +/- 19 lx. The nocturnal onset of plasma melatonin secretion was used as a marker of circadian phase. A phase response curve was used to summarize the phase-shifting effects of exercise as a function of the timing of exercise. A significant effect of time of day on circadian phase shifts was observed (P < 0.004). Over the interval from the melatonin onset before exercise to the first onset after exercise, circadian phase was significantly advanced in the evening exercise group by 30 +/- 15 min (SE) compared with the phase delays observed in the no-exercise group (-25 +/- 14 min, P < 0.05). Phase shifts in response to evening exercise exposure were attenuated on the second day after exercise exposure and no longer significantly different from phase shifts observed in the absence of exercise. Unanticipated transient elevations of melatonin levels were observed in response to nocturnal exercise and in some evening exercise subjects. Taken together with the results from previous studies in humans and diurnal rodents, the current results suggest that 1) a longer duration of exercise exposure and/or repeated daily exposure to exercise may be necessary for reliable phase-shifting of the human circadian system and that 2) early evening exercise of high intensity may induce phase advances relevant for nonphotic entrainment of the human circadian system.

Adult↗

PubMed1989

[The clinical significance of the low level treadmill exercise test in acute myocardial infarction].

To clarify the clinical significance of the exercise test in acute myocardial infarction (AMI), the relationship between the results of exercise test and clinical features was studied. The low level treadmill exercise test (maximum exercise time was 1080 seconds and the maximum oxygen consumption was 7 METs) were performed in 111 patients within 2 months after the onset of AMI. The exercise time, the endpoint of the exercise test, the exercise-induced ST-segment deviation and ventricular premature beats (VPC) were evaluated from the exercise tests. Among the clinical features, age, sex, the severity in the acute period (Killip's classification and Forrester's hemodynamic subset), the findings in cardioangiography (the number of diseased coronary arteries, left ventricular ejection fraction and abnormal wall motion in the left ventricle) and short term prognosis after AMI were evaluated. The prognosis was judged as poor when cardiac death, congestive heart failure, postinfarction angina, the decrease of exercise tolerance and reattack of AMI occurred, or when an aorto-coronary bypass graft or percutaneous transluminal coronary angioplasty was performed. The exercise time was shorter in patients over the age of 60 years (578 +/- 360 seconds) than in younger patients (818 +/- 296 seconds), and also in females (487 +/- 392 seconds) than in males (767 +/- 319 seconds). The patients classed as Forrester's hemodynamic subset IV had shorter exercise time than the others. But, there was no relationship between the exercise time and Killip's classification. Low left ventricular ejection fraction (55% or less) was associated with short exercise time and the apperance of exercise-induced VPC. But the number of diseased coronary artery and abnormal wall motion in the left ventricle were not related to the exercise test. The patients with high exercise tolerance (4.2 METs or more) in the AMI recovery period showed better prognosis than those with low exercise tolerance within one year after AMI (96% vs 50%, p less than 0.0001, respectively). In conclusion, the low level exercise test in AMI was influenced by age, sex and cardiac function, and it was useful in evaluating the short term prognosis after AMI.

Adult↗

PubMed1991

Plasma glucose metabolism during exercise in humans.

Plasma glucose is an important energy source in exercising humans, supplying between 20 and 50% of the total oxidative energy production and between 25 and 100% of the total carbohydrate oxidised during submaximal exercise. Plasma glucose utilisation increases with the intensity of exercise, due to an increase in glucose utilisation by each active muscle fibre, an increase in the number of active muscle fibres, or both. Plasma glucose utilisation also increases with the duration of exercise, thereby partially compensating for the progressive decrease in muscle glycogen concentration. When compared at the same absolute exercise intensity (i.e. the same VO2), reliance on plasma glucose is also greater during exercise performed with a small muscle mass, i.e. with the arms or just 1 leg. This may be due to differences in the relative exercise intensity (i.e. the %VO2peak), or due to differences between the arms and legs in their fitness for aerobic activity. The rate of plasma glucose utilisation is decreased when plasma free fatty acid or muscle glycogen concentrations are very high, effects which are probably mediated by increases in muscle glucose-6-phosphate concentration. However, glucose utilisation is also reduced during exercise following a low carbohydrate diet, despite the fact that muscle glycogen is also often lower. When exercise is performed at the same absolute intensity before and after endurance training, plasma glucose utilisation is lower in the trained state. During exercise performed at the same relative intensity, however, glucose utilisation may be lower, the same, or actually higher in trained than in untrained subjects, because of the greater absolute VO2 and demand for substrate in trained subjects during exercise at a given relative exercise intensity. Although both hyperglycaemia and hypoglycaemia may occur during exercise, plasma glucose concentration usually remains relatively constant. Factors which increase or decrease the reliance of peripheral tissues on plasma glucose during exercise are therefore generally accompanied by quantitatively similar increases or decreases in glucose production. These changes in total glucose production are mediated by changes in both hepatic glycogenolysis and hepatic gluconeogenesis. Glycogenolysis dominates under most conditions, and is greatest early in exercise, during high intensity exercise, or when dietary carbohydrate intake is high. The rate of gluconeogenesis is increased when exercise is prolonged, preceded by a restricted carbohydrate intake, or performed with the arms. Both glycogenolysis and gluconeogenesis appear to be decreased by endurance exercise training. These effects are due to changes in both the hormonal milieu and in the availability of hepatic glycogen and gluconeogenic precursors.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Glucose↗

PubMed2006

Airway response during exercise and hyperpnoea in non-asthmatic and asthmatic individuals.

Airway calibre is an important determinant of air flow and respiratory work both at rest and during exercise. While much is understood about control of airway calibre at rest, less is known about the dynamics and changes in airway resistance during exercise, especially in those with asthma. This article provides an overview of the current understanding provided by the literature that has addressed airway resistance during exercise in normal non-asthmatic individuals and in those with asthma. There are many interesting studies that provide some insight into this issue. In general, non-asthmatic individuals appear to have near maximally or maximally dilated airways at rest and, thus, have little change associated with exercise, at least during short duration exercise of <15 minutes. However, potent bronchodilating influences are in operation during the exercise as shown by exercise data from normal subjects with pharmacologically pre-constricted airways. In contrast, dynamic exercise has consistently demonstrated improved airway calibre in asthmatic individuals. Again, the exercise has typically been <15 minutes. Data from longer duration exercise (20-30 minutes) are lacking in normal subjects but suggest declining pulmonary function over time during exercise in asthmatic individuals after the initial bronchodilation. However, the lack of non-asthmatic controls and small subject numbers in these studies leave much remaining to be studied in this regard. Handgrip exercise in asthmatic individuals also elicits bronchodilation raising interesting questions as to potential mechanisms. Isocapnic voluntary hyperpnoea matched to exercise hyperpnoea levels induces bronchodilation in asthmatic individuals during both short- and longer-term bouts up to 20 minutes. This result in longer-term isocapnic hyperpnoea apparently deviates from the response of asthmatic individuals to the hyperpnoea of longer-term dynamic exercise raising interesting questions. Voluntary hyperpnoea is important to this discussion as this technique is often used to assess the prevalence of exercise-induced asthma. While much is yet to be understood, dynamic, and possibly isometric, exercise is a powerful bronchodilator, at least over a short period of up to 15 minutes. It remains to be determined how airways respond to dynamic exercise of >15 minutes in both normal and asthmatic individuals and the mechanisms operating in the various circumstances. Additionally, attention to resting pulmonary function in asthmatic individuals must be given as those with constricted airways may differ in response to exercise, or to voluntary hyperpnoea, from those with normal airway function at rest.

Airway Resistance↗

PubMed1995

Prescribing exercise in multiple short bouts versus one continuous bout: effects on adherence, cardiorespiratory fitness, and weight loss in overweight women.

OBJECTIVE: To investigate whether prescribing exercise in several short-bouts versus one long-bout per day would enhance exercise adherence, cardiorespiratory fitness, and weight loss in overweight adult females in a behavioral weight control program. DESIGN: Randomized controlled trial with subjects randomized to either a short-bout exercise group (SB, n = 28, age = 40.4 +/- 5.9 yrs) or a long-bout exercise group (LB, n = 28, age = 40.9 +/- 7.3 yrs), with subjects followed for a period of 20 weeks. Both groups were instructed to exercise 5 days per week with exercise duration progressing from 20 to 40 min per day. The LB group performed one exercise bout per day, whereas the SB group performed multiple 10 min bouts of exercise per day. The recommended caloric intake for all subjects was 5022-6277 kJ/day (1200-1500 kcal/day), with fat reduced to 20% of caloric intake. SUBJECTS: Fifty-six obese, sedentary females (BMI = 33.9 +/- 4.1 kg/m2). MEASUREMENTS: Exercise participation was assessed from self-reported diaries and Tri-Trac Accelerometers. Cardiorespiratory fitness was assessed using a submaximal cycle ergometer test. RESULTS: Exercising in multiple short-bouts per day improved adherence to exercise: the SB group reported exercising on a greater number of days (mean +/- s.d. = 87.3 +/- 29.5 days vs 69.1 +/- 28.9 days; P < 0.05) and for a greater total duration (223.8 +/- 69.5 min/week vs 188.2 +/- 58.4 min/week; P = 0.08) than the LB group. Predicted VO2Peak increased by 5.6% and 5.0% for the LB and SB groups, respectively (P < 0.05). There was a trend for the weight loss to be greater in the SB group (-8.9 +/- 5.3 kg) compared to the LB group (-6.4 +/- 4.5 kg; P < 0.07). CONCLUSION: These results suggest that short-bouts of exercise may enhance exercise adherence. Short-bouts of exercise may also enhance weight loss and produce similar changes in cardiorespiratory fitness when compared to long-bouts of exercise. Thus, short-bouts of exercise may be preferred when prescribing exercise to obese adults.

Adult↗

PubMed1995

Are oxygen uptake kinetics at the onset of exercise speeded up by local metabolic status in active muscles?

To assess the rate-limiting factor of oxygen uptake (VO2) kinetics at the onset of exercise, six healthy male sedentary subjects performed repeated one-legged constant-load cycle exercise. The one-legged constant-load exercise test consisted of two 5-min periods of pedalling at an exercise intensity of 50 W, with a 5-min rest between periods (these exercise periods, i.e. first and second exercises, were performed by the same leg). The exercise was then repeated using the other leg. In addition, two-legged incremental exercise was investigated to establish whether VO2 kinetics were affected by slower heart rate kinetics. The incremental exercise test consisted of two-legged pedalling first with the cycle unloaded as a warm-up for 5 min followed by 50-W exercise for 5 min. The exercise intensity was then increased to 100 W for 5 min. During exercise, gas exchange parameters were determined by the breath-by-breath method and cardiac output (Qc) was determined continuously by an impedance technique with a computer-based automated system. To determine the kinetics of heart rate (HR), Qc, and VO2, a best fit procedure was employed using least-squares criteria with a time delay, except during the initial increase. During the one-legged constant-load exercise test, VO2 kinetics were significantly accelerated by repeated exercise using the same leg. On the other hand, when the exercise was changed to the other leg, VO2 kinetics were significantly slower, although Qc kinetics continued to be faster. During the incremental exercise test, although the HR response was slower at the transition from 50-W to 100-W exercise than at the transition from warm-up to 50-W exercise, there were no significant changes in VO2 kinetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Stimulation of myofibrillar protein synthesis in hindlimb suspended rats by resistance exercise and growth hormone.

The objective of this study was to determine the ability of a single bout of resistance exercise alone or in combination with recombinant human growth hormone (rhGH) to stimulate myofibrillar protein synthesis (Ks) in hindlimb suspended (HLS) adult female rats. Plantar flexor muscles were stimulated with resistance exercise, consisting of 10 repetitions of ladder climbing on a 1 m grid (85 degrees), carrying an additional 50% of their body weight attached to their tails. Saline or rhGH (1 mg/kg) was administered 30' prior to exercise, and Ks was determined with a constant infusion of 3H-Leucine at 15', 60', 180', and 360' following exercise. Three days of HLS depressed Ks approximately 65% and 30-40% in the soleus and gastrocnemius muscles, respectively (p < or = 0.05). Exercise increased soleus Ks in saline-treated rats 149% 60' following exercise (p < or = 0.05), decaying to that of non-exercised animals during the next 5 hours. Relative to suspended, non-exercised rats rhGH+exercise increased soleus Ks 84%, 108%, and 72% at 15', 60' and 360' following exercise (p < or = 0.05). Gastrocnemius Ks was not significantly increased by exercise or the combination of rhGH and exercise up to 360' post-exercise. Results from this study indicate that resistance exercise stimulated Ks 60' post-exercise in the soleus of HLS rats, with no apparent effect of rhGH to enhance or prolong exercise-induced stimulation. Results suggests that exercise frequency may be important to maintenance of the slow-twitch soleus during non-weightbearing, but that the ability of resistance exercise to maintain myofibrillar protein content in the gastrocnemius of hindlimb suspended rats cannot be explained by acute stimulation of synthesis.

Animals↗