SEARCH · PubMed Health

Results for “Exercise training”

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 883 records · Page 49Linked to original sources

PubMed1993

Endurance exercise training: conditions of enhanced hemodynamic responses and tolerance to LBNP.

In cross-sectional comparisons, several investigators have reported highly trained endurance athletes to have a prevalence toward orthostatic hypotension and intolerance compared with average fit individuals. These observations have raised concern that regular exercise designed to increase aerobic capacity may impair regulatory mechanisms of blood pressure control and that perhaps certain populations of individuals with a predisposition for fainting exhibit an inability to elevate heart rate, vasoactive hormones, and peripheral resistance during an orthostatic challenge. In longitudinal experiments, when exercise training was performed by subjects who increased their aerobic capacity by 20% but maintained VO2max below 50 ml.kg-1.min-1, tolerance to lower body negative pressure (LBNP) was increased by 28%. Exercise training did not compromise baroreflex functions despite evidence of increased resting vagal cardiac tone and reduced sympathetic tone. In contrast to fainters, increased orthostatic tolerance in the exercised-trained subjects was associated with no alteration in their ability to elevate heart rate, vasoactive hormones, and peripheral resistance at peak LBNP. However, cardiac output and mean arterial blood pressure were maintained during higher submaximal LBNP levels by a 20% increase in stroke volume. The elevation in stroke volume during LBNP after training was associated with blood volume expansion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed2000

Blood volume: importance and adaptations to exercise training, environmental stresses, and trauma/sickness.

This paper reviews the influence of several perturbations (physical exercise, heat stress, terrestrial altitude, microgravity, and trauma/sickness) on adaptations of blood volume (BV), erythrocyte volume (EV), and plasma volume (PV). Exercise training can induce BV expansion: PV expansion usually occurs immediately, but EV expansion takes weeks. EV and PV expansion contribute to aerobic power improvements associated with exercise training. Repeated heat exposure induces PV expansion but does not alter EV. PV expansion does not improve thermoregulation, but EV expansion improves thermoregulation during exercise in the heat. Dehydration decreases PV (and increases plasma tonicity) which elevates heat strain and reduces exercise performance. High altitude exposure causes rapid (hours) plasma loss. During initial weeks at altitude, EV is unaffected, but a gradual expansion occurs with extended acclimatization. BV adjustments contribute, but are not key, to altitude acclimatization. Microgravity decreases PV and EV which contribute to orthostatic intolerance and decreased exercise capacity in astronauts. PV decreases may result from lower set points for total body water and central venous pressure, while EV decreases may result from increased erythrocyte destruction. Trauma, renal disease, and chronic diseases cause anemia from hemorrhage and immune activation which suppresses erythropoiesis. The re-establishment of EV is associated with healing, improved life quality, and exercise capabilities for these injured/sick persons.

Adaptation, Physiological↗

PubMed1997

Voluntary exercise training enhances glucose transport in muscle stimulated by insulin-like growth factor I.

Skeletal muscle glucose transport can be regulated by hormonal factors such as insulin and insulin-like growth factor I (IGF-I). Although it is well established that exercise training increases insulin action on muscle glucose transport, it is currently unknown whether exercise training leads to an enhancement of IGF-I-stimulated glucose transport in skeletal muscle. Therefore, we measured glucose transport activity [by using 2-deoxy-D-glucose glucose (2-DG) uptake] in the isolated rat epitrochlearis muscle stimulated by submaximally and maximally effective concentrations of insulin (0.2 and 13.3 nM) or IGF-I (5 and 50 nM) after 1, 2, and 3 wk of voluntary wheel running (WR). After 1 wk of WR, both submaximal and maximal insulin-stimulated 2-DG uptake rates were significantly (P < 0.05) enhanced (43 and 31%) compared with those of sedentary controls, and these variables were further increased after 2 (86 and 57%) and 3 wk (71 and 70%) of WR. Submaximal and maximal IGF-I-stimulated 2-DG uptake rates were significantly enhanced after 1 wk of WR (82 and 61%, and these increases did not expand substantially after 2 (71 and 58%) and 3 wk (96 and 70%) of WR. This enhancement of hormone-stimulated 2-DG uptake in WR muscles preceded any alteration in glucose transporter (GLUT-4) protein level, which increased only after 2 (24%) and 3 wk (54%) of WR. Increases in GLUT-4 protein were significantly correlated (r = 0.844) with increases in citrate synthase. These results indicate that exercise training can enhance both insulin-stimulated and IGF-I-stimulated muscle glucose transport activity and that these improvements can develop without an increase in GLUT-4 protein.

Animals↗

PubMed1988

Exercise training in patients with severe left ventricular dysfunction. Hemodynamic and metabolic effects.

We studied the effects of exercise training in patients with chronic heart failure attributed to left ventricular dysfunction (ejection fraction, 24 +/- 10%). Twelve ambulatory patients with stable symptoms underwent 4-6 months of conditioning by exercising 4.1 +/- 0.6 hr/wk at a heart rate corresponding to 75% of peak oxygen consumption. Before and after training, patients underwent maximal bicycle exercise testing with direct measurement of central hemodynamic, leg blood flow, and metabolic responses. Exercise training resulted in a decrease in heart rate at rest and submaximal exercise and a 23% increase in peak oxygen consumption from 16.8 +/- 3.8 to 20.6 +/- 4.7 ml/kg/min (p less than 0.01). Heart rate, arterial lactate, and respiratory exchange ratio were unchanged at peak exercise after training. Maximal cardiac output tended to increase from 8.9 +/- 2.7 to 9.9 +/- 3.2 1/min and contributed to improved peak oxygen consumption in some patients, although this change did not reach statistical significance (p = 0.13). Rest and exercise measurements of left ventricular ejection fraction, left ventricular end-diastolic volume, and left ventricular end-systolic volume were unchanged. Right atrial, pulmonary arterial, pulmonary capillary wedge, and systemic arterial pressures were not different after training. Training induced several important peripheral adaptations that contributed to improved exercise performance. At peak exercise, systemic arteriovenous oxygen difference increased from 13.1 +/- 1.4 to 14.6 +/- 2.3 ml/dl (p less than 0.05). This increase was associated with an increase in peak-exercise leg blood flow from 2.5 +/- 0.7 to 3.0 +/- 0.8 l/min (p less than 0.01) and an increase in leg arteriovenous oxygen difference from 14.5 +/- 1.3 to 16.1 +/- 1.9 ml/dl (p = 0.07). Arterial and femoral venous lactate levels were markedly reduced during submaximal exercise after training, even though cardiac output and leg blood flow were unchanged at these workloads. Thus, ambulatory patients with chronic heart failure can achieve a significant training effect from long-term exercise. Peripheral adaptations, including an increase in peak blood flow to the exercising leg, played an important role in improving exercise tolerance.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMedDate not supplied

Exercise training can modify the natural history of diabetic peripheral neuropathy.

BACKGROUND: Diabetes is the most important cause of peripheral neuropathy (DPN). No definitive treatment for DPN has been established, and very few data on the role of exercise training on DPN have been reported. AIM OF THE STUDY: We sought to examine the effects of long-term exercise training on the development of DPN in both Types 1 and 2 diabetic patients. PARTICIPANTS AND METHODS: Seventy-eight diabetic patients without signs and symptoms of peripheral DPN were enrolled, randomized, and subdivided in two groups: 31 diabetic participants [15 f, 16 m; 49+/-15.5 years old; body mass index (BMI)=27.9+/-4.7], who performed a prescribed and supervised 4 h/week brisk walking on a treadmill at 50% to 85% of the heart rate reserve (exercise group: EXE), and a control group of 47 diabetic participants (CON; 24 f, 23 m; 52.9+/-13.4 years old; BMI=30.9+/-8.4). Vibration perception threshold (VPT), nerve distal latency (DL), nerve conduction velocity (NCV), and nerve action potential amplitude (NAPA) in the lower limbs were measured. RESULTS: We found significant differences on Delta (delta) in NCV for both peroneal and sural motor nerve between the EXE and CON groups during the study period (P<.001, for both). The percentage of diabetic patients that developed motor neuropathy and sensory neuropathy during the 4 years of the study was significantly higher in the CON than the EXE group (17% vs. 0.0%, P<.05, and 29.8% vs. 6.45%, P<.05, respectively). In addition, the percentage of diabetic patients who developed increased VPT (25 V) during the study was significantly higher in the CON than the EXE group (21.3% vs. 12.9%, P<.05). Change on Hallux VPT from baseline to the end of the study was significantly different between the EXE and CON groups (P<.05); no significant change in Malleolus VPT between the two groups occurred. CONCLUSIONS: This study suggests, for the first time, that long-term aerobic exercise training can prevent the onset or modify the natural history of DPN.

Adult↗

PubMed1990

Exercise training attenuates diet-induced reduction in metabolic rate.

The combined influence of exercise training and dietary restriction on daily energy expenditure was evaluated by exposing 48 male Sprague-Dawley rats to one of three food intake conditions [ad libitum (AL), moderately restricted (MR), or severely restricted (SR)] and to one of two exercise conditions [treadmill exercised (E) or cage confined (CC)]. After 10 wk of exercise and dietary restriction, the MR-CC and MR-E rats weighed 84 and 86%, respectively, of AL-CC, whereas the SR-CC and SR-E rats weighed 66 and 68% of AL-CC. Dietary restriction and subsequent weight loss produced significant reductions in both total and resting daily energy expenditure. Exercise partially reversed this effect, but the extent of this reversal diminished as the severity of dietary restriction was increased. These results raise the distinct possibility that inconsistencies in the current literature concerning the effects of exercise on whole body metabolism during periods of dietary restriction might be reconciled by an appreciation and an understanding of the influence that duration of exercise training and severity of food restriction have on this measure.

Animals↗

PubMed2002

Heritability of HR and BP response to exercise training in the HERITAGE Family Study.

PURPOSE: The heritability of the response to exercise training in resting blood pressure (BP) and heart rate (HR) was assessed in 482 Caucasian individuals comprising 98 families participating in the HERITAGE Family Study. METHODS: All individuals were sedentary at the baseline visit (time 1 measurement). After completing a 20-wk exercise-training program, subjects were measured again (time 2). A familial correlation model was used to assess the heritability (genetic plus familial environmental) of the response in resting systolic BP (SBP), diastolic BP (DBP), and HR, computed as the difference between the two measurement times. This response was adjusted for the effects of baseline levels and age within sex and generation groups. Analyses were conducted separately in a subsample of families in which at least one family member was considered to have elevated BP (95th percentile; SBP > or = 135 or DBP > or = 80). RESULTS: Several novel findings emerged from this study. First, the SBP and HR response may be influenced by genetic factors. The maximal heritabilities were 20% (SBP) and 36% (HR) in the elevated BP, 18% and 24% in the complete, and not significant in the normotensive samples. For DBP, there were cohort effects (significant sibling and spouse but not parent-offspring correlations) in the complete and normotensive samples that may be due to generation-specific environmental influences. CONCLUSION: The trainability of SBP and HR in families with elevated BP appears to be determined in part by genetic factors, whereas DBP trainability may be more a function of environmental effects.

Adolescent↗

PubMed2004

Quality of life, psychological and physiological changes following exercise training in patients with chronic heart failure.

OBJECTIVE: To assess the physiological and psychosocial effects of exercise training in chronic heart failure. SUBJECTS/PATIENTS: Twenty-six men with heart failure (New York Heart Association functional classes II and III) aged 52.5 (SD 9.8) years, were studied. METHODS: The subjects were randomized either to rehabilitation group (Group A: 16 patients), participating in a 6-month exercise training program, or to control group (Group B: 10 patients). A psychosocial assessment, which included affective (Beck Depression Inventory and Hospital Anxiety and Depression Scale), quality of life (Quality of Life Index, Minnesota Living with Heart Failure Questionnaire and the Scale of Life Satisfaction) and personality (Eysenck Personality Questionnaire) parameters, was performed at the beginning and the end of the study. RESULTS: After training VO2 peak increased by 36% and exercise time by 35%, p < 0.05. A significant decrease in anxiety and depression was also observed. Moreover, trained patients demonstrated a significant improvement in quality of life. No significant correlations were found between deltaVO2 peak and all psychosocial parameter gains. However, the more depressed patients showed the largest physiological responses. CONCLUSION: An exercise rehabilitation program in patients with chronic heart failure is useful for improving their work capacity and psychosocial status. Improvements in psychological status seem to be independent of the aerobic gains.

Adult↗

PubMed1991

Effects of aerobic exercise training on symptomatic women with mitral valve prolapse.

The effects of a 12-week aerobic exercise training protocol on 32 symptomatic women with mitral valve prolapse were studied. Subjects were randomly assigned to control or exercise groups. Exercise subjects completed a 12-week (3 times per week) exercise training program based on guidelines established by the American Heart Association for phase II cardiac rehabilitation programs; control group subjects maintained normal activities. Before and after training, subjects underwent maximal multistage treadmill testing, and measurements were obtained for plasma catecholamine levels at rest and during peak exercise; they completed the State Trait Anxiety Inventory and General Well-Being Schedule. Weekly symptom frequency of chest pain, arm pain, palpitations, shortness of breath, fatigue, headache, mood swings, dizziness and syncope were monitored for the 12-week period. Data were analyzed using multivariate analysis of variance, multivariate analysis of covariance, and analysis of covariance with repeated measures. Compared with control subjects, the exercise group showed a significant (p less than 0.05) decrease in State Trait Anxiety Inventory scores, an increase in General Well-Being scores, an increase in functional capacity and a decline in the frequency of chest pain, fatigue, dizziness and mood swings. No statistically significant differences were noted in catecholamine levels at rest or during peak exercise. These findings support the use of aerobic exercise in the management of symptomatic women with mitral valve prolapse.

Adult↗

PubMed1998

Exercise training increases K+-channel contribution to regulation of coronary arterial tone.

The present study examined whether regulation of coronary tone in conduit arteries (>1.0 mm ID) is altered by exercise training. Yucatan miniature swine were treadmill trained for 16-20 wk (Ex) and compared with sedentary counterparts (Sed). Endothelium-denuded arterial rings were stretched to optimal length and allowed to equilibrate for 60 min. Inhibition of either Ca2+-activated channels [1 mM tetraethylammonium (TEA) or 10 nM iberiotoxin (IBTX)] or voltage-dependent K+ channels [1 mM 4-aminopyridine (4-AP)] significantly increased resting tension in both groups; however, the effect of all K+-channel blockers was greater in Ex. Addition of 1 mM sodium nitroprusside reduced resting tension in both groups, confirming the presence of active basal tone; however, sodium nitroprusside-sensitive tone was increased approximately twofold in Ex compared with Sed group. Perforated patch-clamp experiments on isolated smooth muscle cells demonstrated no effect of exercise training on whole cell TEA-sensitive, 4-AP-sensitive, or basal K+ current. Similarly, whereas TEA, 4-AP, and IBTX all decreased resting membrane potential, there was no difference in depolarization between groups. The greater effect of TEA on resting tension in Ex could be mimicked in Sed by addition of the Ca2+-channel agonist BAY K 8644. In conclusion, the greater response to K+-channel blockers after exercise training is consistent with an increased contribution of K+ channels to regulation of basal tone in conduit coronary arteries. The lack of an effect of training on K+ current characteristics or membrane potential responses in isolated cells suggests that a requisite factor for enhanced K+-channel activation in arteries from Ex, possibly stretch, is absent in isolated cells.

4-Aminopyridine↗

PubMed2000

Low-functioning hemodialysis patients improve with exercise training.

The Renal Exercise Demonstration Project provided two different approaches to exercise programming to a group of hemodialysis patients. Physical functioning and self-reported health-related quality of life were measured at baseline, after 2 months of independent exercise, and again after 2 months of in-center cycling. This study compares the responses to intervention of patients who initially scored low (<34) on the Physical Component Scale (PCS) on the Medical Outcomes Study Short-Form 36 questionnaire to those who initially scored higher (>34) on the same scale. The high-PCS group scored higher on all physical function tests (normal gait speed, fast gait speed, and sit-to-stand test) at each testing time than the low-PCS group. The high-PCS group improved only on the sit-to-stand test, whereas the low-PCS group improved in all three physical function tests. There were significant differences between the groups in change over time in all the physical scales and the PCS over time, with the low-PCS group showing improvements in response to the intervention and the high-PCS group showing no change over time. No differences in change over time were noted between the groups on the mental scales in either group. We conclude that low-functioning hemodialysis patients can benefit from exercise counseling in both objective measures of physical functioning and self-reported physical functioning. The impact of such interventions seems to be more profound in the lowest functioning patients.

Analysis of Variance↗

PubMed2000

Effect of deconditioning on cortical and cancellous bone growth in the exercise trained young rats.

Exercise enhances bone growth and increases peak bone mass. The aim of this study was to determine whether or not 4 weeks of deconditioning after 8 weeks of exercise in growing rats would result in a decrease in bone gain or reverse the benefits of exercise. Fifty 4-week-old female Sprague-Dawley rats were randomized by a stratified weight method into 5 groups with 10 rats in each group: 8 weeks exercise (8EX), 8 weeks sedentary control (8S), 12 weeks exercise (12EX), 8 weeks exercise followed by 4 weeks sedentary (8EX4S), and 12 weeks sedentary control (12S). The exercise consisted of running on a treadmill with a 5 degrees slope at 24 m/minute for 1 h/day and 5 days/week. After each period of exercise, cancellous and cortical bone histomorphometry were performed on double fluorescent labeled 5-microm-thick sections of the proximal tibia and 40-microm-thick sections of the tibial shaft, respectively. Eight and 12 weeks of exercise resulted in a significant increase in the body weight and gastrocnemius muscle weight by two-way analysis of variance (ANOVA). The femoral wet weight (mg; mean +/- SD; 8EX, 781 +/- 45.1 vs. 8S, 713 +/- 40.5; p < 0.05; 12EX, 892 +/- 41.6 vs. 12S, 807 +/- 19.8; p < 0.05) was significantly higher in the exercise group than that in the respective control groups. The femoral wet weight and bone volume (BV) of the 8EX4S group (818 +/- 46.2 mg and 531 +/- 31.2 microl, respectively) were significantly lower than those of the 12EX group (p < 0.05) and did not differ significantly from those of the 12S groups. The cancellous BV was significantly higher in the 8EX and 12EX groups than that in the respective sedentary groups (p < 0.05). The cortical bone area of the tibial shaft was also significantly higher in the 12EX than that in the 12S group (p < 0.05). The increase in the cancellous BV or cortical bone area was caused by an increase in the mineral apposition rate (MAR), without a significant effect in the labeled perimeter. The bone formation rate (BFR; microm3/microm2 per day) in the cancellous bone (12EX, 27.9 +/- 7.74 vs. 12S, 15.4 +/- 4.56; p < 0.05) or periosteal surface (12EX, 127.6 +/- 27.7 vs. 12S, 79.5 +/- 18.6; p < 0.05) was significantly higher in the exercised groups than that in the respective control group (p < 0.05). Again, deconditioning resulted in a decrease in the cancellous BFR, BV, periosteal BFR, and cortical bone area to levels not significantly different from the 12S group. In conclusion, our findings showed that exercised growing rats, when deconditioned, lost the benefits gained through exercise and their bone parameters were reduced to levels not different from the sedentary control. Thus, continued exercise is required to maintain high bone mass.

Animals↗

PubMed2005

Endurance exercise training attenuates cardiac beta2-adrenoceptor responsiveness and prevents ventricular fibrillation in animals susceptible to sudden death.

Enhanced cardiac beta(2)-adrenoceptor (beta(2)-AR) responsiveness can increase susceptibility to ventricular fibrillation (VF). Exercise training can decrease cardiac sympathetic activity and could, thereby, reduce beta(2)-AR responsiveness and decrease the risk for VF. Therefore, dogs with healed myocardial infarctions were subjected to 2 min of coronary occlusion during the last minute of a submaximal exercise test; VF was observed in 20 susceptible, but not in 13 resistant, dogs. The dogs were then subjected to a 10-wk exercise-training program (n = 9 susceptible and 8 resistant) or an equivalent sedentary period (n = 11 susceptible and 5 resistant). Before training, the beta(2)-AR antagonist ICI-118551 (0.2 mg/kg) significantly reduced the peak contractile (by echocardiography) response to isoproterenol more in the susceptible than in the resistant dogs: -45.5 +/- 6.5 vs. -19.2 +/- 6.3%. After training, the susceptible and resistant dogs exhibited similar responses to the beta(2)-AR antagonist: -12.1 +/- 5.7 and -16.2 +/- 6.4%, respectively. In contrast, ICI-118551 provoked even greater reductions in the isoproterenol response in the sedentary susceptible dogs: -62.3 +/- 4.6%. The beta(2)-AR agonist zinterol (1 microM) elicited significantly smaller increases in isotonic shortening in ventricular myocytes from susceptible dogs after training (n = 8, +7.2 +/- 4.8%) than in those from sedentary dogs (n = 7, +42.8 +/- 5.8%), a response similar to that of the resistant dogs: +3.0 +/- 1.4% (n = 6) and +3.2 +/- 1.8% (n = 5) for trained and sedentary, respectively. After training, VF could no longer be induced in the susceptible dogs, whereas four sedentary susceptible dogs died during the 10-wk control period and VF could still be induced in the remaining seven animals. Thus exercise training can restore cardiac beta-AR balance (by reducing beta(2)-AR responsiveness) and could, thereby, prevent VF.

Adrenergic beta-Agonists↗

PubMed1995

Exercise training alters aortic vascular reactivity in hypothyroid rats.

Hypothyroidism induces a number of cardiovascular adaptations in rats, including decreases in blood flow to high-oxidative skeletal muscle and increases in total peripheral resistance. Conversely, exercise training results in elevations in blood flow to high-oxidative skeletal muscle and decreases in vascular resistance. The purpose of this study was to determine whether hypothyroidism induces changes in the vasomotor responses of arterial vessels and whether exercise training modifies these responses. Rats were divided into three groups, sedentary euthyroid (S-Eut), sedentary hypothyroid (S-Hypo), and exercise-trained hypothyroid (ET-Hypo). Responses to vasoactive compounds were examined in vitro using abdominal aortic rings. Maximal isometric contractile tension (g/mm2) evoked by KCl and norepinephrine (NE) were not different among groups. However, sensitivity to KCl [agonist concentration producing 50% of maximal vasoconstrictor response (EC50; in mM): S-Eut, 21.1 +/- 1.1; S-Hypo, 35.7 +/- 2.7; ET-Hypo, 43.8 +/- 2.0] and to NE [EC50 (in M): S-Eut, 4.0 x 10(-8) +/- 2.3 x 10(-8); S-Hypo, 8.3 x 10(-8) +/- 3.4 x 10(-8); ET-Hypo, 3.6 x 10(-7) +/- 1.1 x 10(-7)] was different among groups, and in the order S-Eut > S-Hypo > ET-Hypo. Maximal vasodilator responses induced by acetylcholine (10(-7) M NE preconstriction) were lower in rings from S-Hypo animals than those from S-Eut and ET-Hypo rats. Dilatory responses induced by sodium nitroprusside (SNP) with the same NE preconstriction were not different among groups. However, with a 10(-4) M NE preconstriction, maximal dilatory responses induced by SNP were lower in vessels from hypothyroid animals. Dilatory responses to forskolin (10(-4) M NE preconstriction) were not different among groups.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1991

Energetic and metabolic studies of intragastric infusion of calories before and after exercise training.

The technique of intragastric infusion of calories was used to examine the energetics and metabolic response to fasting, feeding and overfeeding states in adult, sedentary subjects. All subjects were studied before and after participating in a 12-week aerobic exercise training program that increased maximum aerobic capacity by an average of 15.6 percent. Body weight did not change during the exercise program, but there was a slight and statistically significant increase in fat-free mass and a significant decrease in fat mass. The exercise program did not affect food intake (as determined from food records). When subjects were studied before exercise training, there was no increase in energy expenditure above fasting levels during continuous infusion of calories at a rate near the subject's maintenance energy requirements. When infusion rate was increased to twice maintenance, energy expenditure increased significantly and produced a measurable thermic effect of food. The changes in glucose, insulin and free fatty acids did not parallel the changes in energy expenditure, but changes in lactate levels did. Moreover, there were some gender differences in the pattern of substrate and hormone changes with changes in feeding state. Exercise training did not alter either energy expenditure or the pattern of changes in substrates and hormones with changes in feeding state. In summary, the exercise program led to changes in body composition without measurable changes in either food intake (assessed from diet records) or energy expenditure (assessed during fasting and continuous infusion of calories). The change in body composition must have been due to either (1) the energy cost of the exercise itself, or (2) changes in the substrates used for oxidation, either during or following exercise bouts. We conclude that exercise, unlike food restriction, can lead to changes in body composition without altering body weight or metabolic rate, and can contribute to the acquisition and maintenance of a desirable body weight and composition.

Adipose Tissue↗

PubMed2006

Effect of a periodized exercise training and active recovery program on antitumor activity and development of dendritic cells.

AIM: Dendritic cells (DCs) are potent antigen-presenting cells that promote antitumor immunity in vivo when pulsed with tumor antigen. No studies have indicated that exercise training affects DC function. The purpose of this study was to investigate the effect of a 5-week periodized exercise training and active recovery program on the development of DCs, and to test their effect on the antitumor immunity of mononuclear cells (MNC) from blood and spleen against human leukemic U937 and murine lymphoma Yac-1 cells, respectively. METHODS: Male Fisher 344 rats were divided into 2 groups: exercise and non-exercise group. The training protocol consisted of running on a motor-driven treadmill 6 days a week for consecutive 5 weeks, during which the running time, treadmill speed, and incline gradient were increased weekly. Active recovery parameters were set at 30% of the intensity of the previous day. RESULTS: DC numbers increased significantly (P<0.05) in the exercise group compared to controls, but there were no significant changes in the expression of surface antigens CD80 and CD86. In exercise group MNC-conditioned medium (CM) prepared with 50 microg/mL phytohemagglutinin (PHA) significantly inhibited proliferation of U937 cells, and splenocyte-CM with PHA at 20 and 40 microg/mL significantly inhibited proliferation of YAC-1 cells greater than control group. CONCLUSIONS: The 5-week periodized exercise training with active recovery promotes the number of DCs and enhances the activity of DCs against tumor cells.

Animals↗

PubMed2004

Strain-dependent differences in responses to exercise training in inbred and hybrid mice.

The aim of this study was to characterize the response to exercise training in several mouse strains and estimate the genetic contribution to phenotypic variation in the responses to exercise training. Male mice from three inbred strains [C57Bl/6J (BL6), FVB/NJ (FVB), and Balb/cJ (Balb/c)] and three hybrid F(1) strains [CB6F1/J (CB6 = female Balb/c x male BL6), B6F F(1) (female BL6 x male FVB), and FB6 F(1) (female FVB x male BL6)] completed an exercise performance test before and after a 4-wk treadmill running program. Distance was used as the primary estimate of endurance exercise performance. FVB mice showed the greatest response to training, with five- to sevenfold greater increases in distance run compared with BL6 and Balb/c strains. Specifically, BL6, FVB, and Balb/c strains increased distance by 33, 172, and 23%, respectively. A similar pattern of changes across strains was observed for run time (17, 87, and 11%) and work (99, 287, and 57%). As a group, F(1) hybrid mice derived from BL6 and FVB strains showed an intermediate response to training (61%). However, further analysis indicated that training responses in FB6 F(1) mice (80%) were approximately 2.5-fold greater than responses in B6F F(1) mice (33%, P = 0.08). A similar pattern of changes between FB6 and B6F F(1) mice was observed for run time (44.5 and 17%) and work (141 and 59%). These data demonstrate that there are large strain-dependent differences in training responses among inbred mouse strains, suggesting that genetic background contributes significantly to adaptation to exercise. Furthermore, the contrasting responses in B6F and FB6 F(1) strains show that a maternal component strongly influences strain-dependent differences in training responses.

Animals↗

PubMed2005

Behavioural treatments for chronic systemic inflammation: effects of dietary weight loss and exercise training.

Persistent low-grade inflammation, as indicated by higher circulating levels of inflammatory mediators such as C-reactive protein, interleukin-6 and tumour necrosis factor-alpha, is a strong risk factor for several chronic diseases. There are data indicating that decreasing energy intake and increasing physical activity may be effective therapies for reducing overall inflammation. Evidence is strong that circulating levels of inflammatory markers are elevated with total and abdominal obesity, possibly owing to a higher secretion rate of cytokines by adipose tissue in obese people. Moreover, very-low-energy dietary weight loss reduces both circulating markers of inflammation and adipose-tissue cytokine production. Data from several large population-based cohorts show an inverse association between markers of systemic inflammation and physical activity or fitness status; small-scale intervention studies support that exercise training diminishes inflammation. Dietary weight loss plus exercise is likely more effective than weight reduction alone in reducing inflammation. To date, data from randomized, controlled trails designed to definitively test the effects of weight loss or exercise training, or both, on inflammation are limited. Future studies are required to define the amount of weight loss needed for clinically meaningful reductions of inflammation; in addition, fully powered and controlled studies are necessary to clarify the effect of exercise training on chronic, systemic inflammation.

C-Reactive Protein↗