Showing papers on "Physical exercise published in 2000"
TL;DR: Well controlled studies are needed to clarify the mental health benefits of exercise among various populations and to address directly processes underlying the benefits of Exercise on mental health.
Abstract: Physical activity may play an important role in the management of mild-to-moderate mental health diseases, especially depression and anxiety. Although people with depression tend to be less physically active than non-depressed individuals, increased aerobic exercise or strength training has been shown to reduce depressive symptoms significantly. However, habitual physical activity has not been shown to prevent the onset of depression. Anxiety symptoms and panic disorder also improve with regular exercise, and beneficial effects appear to equal meditation or relaxation. In general, acute anxiety responds better to exercise than chronic anxiety. Studies of older adults and adolescents with depression or anxiety have been limited, but physical activity appears beneficial to these populations as well. Excessive physical activity may lead to overtraining and generate psychological symptoms that mimic depression. Several differing psychological and physiological mechanisms have been proposed to explain the effect of physical activity on mental health disorders. Well controlled studies are needed to clarify the mental health benefits of exercise among various populations and to address directly processes underlying the benefits of exercise on mental health.
2,011 citations
TL;DR: This advisory reviews the role of resistance training in persons with and without cardiovascular disease, with specific reference to health and fitness benefits, rationale, the complementary role of stretching, relevant physiological considerations, and safety.
Abstract: Position paper endorsed by the American College of Sports Medicine
Although exercise programs have traditionally emphasized dynamic lower-extremity exercise, research increasingly suggests that complementary resistance training, when appropriately prescribed and supervised, has favorable effects on muscular strength and endurance, cardiovascular function, metabolism, coronary risk factors, and psychosocial well-being. This advisory reviews the role of resistance training in persons with and without cardiovascular disease, with specific reference to health and fitness benefits, rationale, the complementary role of stretching, relevant physiological considerations, and safety. Participation criteria and prescriptive guidelines are also provided.
Although resistance training has long been accepted as a means for developing and maintaining muscular strength, endurance, power, and muscle mass (hypertrophy),1 2 its beneficial relationship to health factors and chronic disease has been recognized only recently.3 4 5 Prior to 1990, resistance training was not a part of the recommended guidelines for exercise training and rehabilitation for either the American Heart Association or the American College of Sports Medicine (ACSM). In 1990, the ACSM first recognized resistance training as a significant component of a comprehensive fitness program for healthy adults of all ages.6
Both aerobic endurance exercise and resistance training can promote substantial benefits in physical fitness and health-related factors.3 5 Table 1⇓ summarizes these benefits and attempts to weigh them according to the current literature.3 Although both training modalities elicit benefits in most of the variables listed, the estimated weightings (ie, in terms of physiological benefits) are often substantially different. Aerobic endurance training weighs higher in the development of maximum oxygen uptake (Vo2max) and associated cardiopulmonary variables, and it more effectively modifies cardiovascular risk factors associated with the development of coronary artery disease. Resistance training offers greater development of muscular strength, endurance, and mass. It also assists in the …
1,670 citations
TL;DR: A randomized, controlled trial to determine the independent effect of diet-induced or exercise-induced weight loss on obesity and insulin resistance in moderately obese men found that exercise had no independent effect on insulin sensitivity.
Abstract: Background The independent effects of diet- or exercise-induced weight loss on the reduction of obesity and related comorbid conditions are not known. The effects of exercise without weight loss on fat distribution and other risk factors are also unclear. Objective To determine the effects of equivalent diet- or exercise-induced weight loss and exercise without weight loss on subcutaneous fat, visceral fat skeletal muscle mass, and insulin sensitivity in obese men. Design Randomized, controlled trial. Setting University research center. Participants 52 obese men (mean body mass index [+/-SD], 31.3 +/- 2.0 kg/m2) with a mean waist circumference of 110.1 +/- 5.8 cm. Intervention Participants were randomly assigned to one of four study groups (diet-induced weight loss, exercise-induced weight loss, exercise without weight loss, and control) and were observed for 3 months. Measurements Change in total, subcutaneous, and visceral fat; skeletal muscle mass; cardiovascular fitness; glucose tolerance and insulin sensitivity. Results Body weight decreased by 7.5 kg (8%) in both weight loss groups and did not change in the exercise without weight loss and control groups. Compared with controls, cardiovascular fitness (peak oxygen uptake) in the exercise groups improved by approximately 16% (P 0.2). However, these values were significantly greater than those in the control and exercise without weight loss groups (P Conclusions Weight loss induced by increased daily physical activity without caloric restriction substantially reduces obesity (particularly abdominal obesity) and insulin resistance in men. Exercise without weight loss reduces abdominal fat and prevents further weight gain.
1,573 citations
TL;DR: Exercise training improves endothelium-dependent vasodilatation both in epicardial coronary vessels and in resistance vessels in patients with coronary artery disease.
Abstract: Background Studies of the cardioprotective effects of exercise training in patients with coronary artery disease have yielded contradictory results. Exercise training has been associated with improvement in myocardial perfusion even in patients who have progression of coronary atherosclerosis. We therefore conducted a prospective study of the effect of exercise training on endothelial function in patients with coronary artery disease. Methods We randomly assigned 19 patients with coronary endothelial dysfunction, indicated by abnormal acetylcholine-induced vasoconstriction, to an exercise-training group (10 patients) or a control group (9 patients). To reduce confounding, patients with coronary risk factors that could be influenced by exercise training (such as diabetes, hypertension, hypercholesterolemia, and smoking) were excluded. In an initial study and after four weeks, the changes in vascular diameter in response to the intracoronary infusion of increasing doses of acetylcholine (0.072, 0.72, and 7....
1,410 citations
TL;DR: Regular aerobic-endurance exercise attenuates age-related reductions in central arterial compliance and restores levels in previously sedentary healthy middle-aged and older men.
Abstract: Background—A reduction in compliance of the large-sized cardiothoracic (central) arteries is an independent risk factor for the development of cardiovascular disease with advancing age. Methods and...
1,199 citations
TL;DR: It is indicated that regular aerobic exercise can prevent the age-associated loss in endothelium-dependent vasodilation and restore levels in previously sedentary middle aged and older healthy men.
Abstract: Background—In sedentary humans endothelium-dependent vasodilation is impaired with advancing age contributing to their increased cardiovascular risk, whereas endurance-trained adults demonstrate lower age-related risk. We determined the influence of regular aerobic exercise on the age-related decline in endothelium-dependent vasodilation. Methods and Results—In a cross-sectional study, 68 healthy men 22 to 35 or 50 to 76 years of age who were either sedentary or endurance exercise–trained were studied. Forearm blood flow (FBF) responses to intra-arterial infusions of acetylcholine and sodium nitroprusside were measured by strain-gauge plethysmography. Among the sedentary men, the maximum FBF response to acetylcholine was 25% lower in the middle aged and older compared with the young group (P<0.01). In contrast, there was no age-related difference in the vasodilatory response to acetylcholine among the endurance-trained men. FBF at the highest acetylcholine dose was almost identical in the middle aged and ...
970 citations
TL;DR: It is suggested that individuals who exercised at least two to three times a week experienced significantly less depression, anger, cynical distrust, and stress than those exercising less frequently or not at all.
813 citations
TL;DR: It is reported that in rats, running induces uptake of blood insulin-like growth factor I (IGF-I) by specific groups of neurons throughout the brain, and serum IGF-I mediates activational effects of exercise in the brain.
Abstract: Physical exercise increases brain activity through mechanisms not yet known. We now report that in rats, running induces uptake of blood insulin-like growth factor I (IGF-I) by specific groups of neurons throughout the brain. Neurons accumulating IGF-I show increased spontaneous firing and a protracted increase in sensitivity to afferent stimulation. Furthermore, systemic injection of IGF-I mimicked the effects of exercise in the brain. Thus, brain uptake of IGF-I after either intracarotid injection or after exercise elicited the same pattern of neuronal accumulation of IGF-I, an identical widespread increase in neuronal c-Fos, and a similar stimulation of hippocampal brain-derived neurotrophic factor. When uptake of IGF-I by brain cells was blocked, the exercise-induced increase on c-Fos expression was also blocked. We conclude that serum IGF-I mediates activational effects of exercise in the brain. Thus, stimulation of the uptake of blood-borne IGF-I by nerve cells may lead to novel neuroprotective strategies.
799 citations
TL;DR: In patients with stable chronic heart failure, exercise training is associated with reduction of peripheral resistance and results in small but significant improvements in stroke volume and reduction in cardiomegaly.
Abstract: ContextExercise training in patients with chronic heart failure improves work
capacity by enhancing endothelial function and skeletal muscle aerobic metabolism,
but effects on central hemodynamic function are not well established.ObjectiveTo evaluate the effects of exercise training on left ventricular (LV)
function and hemodynamic response to exercise in patients with stable chronic
heart failure.DesignProspective randomized trial conducted in 1994-1999.SettingUniversity department of cardiology/outpatient clinic in Germany.PatientsConsecutive sample of 73 men aged 70 years or younger with chronic heart
failure (with LV ejection fraction of approximately 0.27).InterventionPatients were randomly assigned to 2 weeks of in-hospital ergometer
exercise for 10 minutes 4 to 6 times per day, followed by 6 months of home-based
ergometer exercise training for 20 minutes per day at 70% of peak oxygen uptake
(n=36) or to no intervention (control group; n=37).Main Outcome MeasuresErgospirometry with measurement of central hemodynamics by thermodilution
at rest and during exercise; echocardiographic determination of LV diameters
and volumes, at baseline and 6-month follow-up, for the exercise training
vs control groups.ResultsAfter 6 months, patients in the exercise training group had statistically
significant improvements compared with controls in New York Heart Association
functional class, maximal ventilation, exercise time, and exercise capacity
as well as decreased resting heart rate and increased stroke volume at rest.
In the exercise training group, an increase from baseline to 6-month follow-up
was observed in mean (SD) resting LV ejection fraction (0.30 [0.08] vs 0.35
[0.09]; P=.003). Mean (SD) total peripheral resistance
(TPR) during peak exercise was reduced by 157 (306) dyne/s/cm−5 in the exercise training group vs an increase of 43 (148) dyne/s/cm−5 in the control group (P=.003), with
a concomitant increase in mean (SD) stroke volume of 14 (22) mL vs 1 (19)
mL in the control group (P=.03). There was a small
but significant reduction in mean (SD) LV end diastolic diameter of 4 (6)
mm vs an increase of 1 (4) mm in the control group (P<.001).
Changes from baseline in resting TPR for both groups were correlated with
changes in stroke volume (r=−0.76; P<.001) and in LV end diastolic diameter (r=0.45; P<.001).ConclusionsIn patients with stable chronic heart failure, exercise training is
associated with reduction of peripheral resistance and results in small but
significant improvements in stroke volume and reduction in cardiomegaly.
710 citations
TL;DR: It is concluded that physical training can be considered to play an important, if not essential role in the treatment and prevention of insulin insensitivity.
Abstract: Physical activity has a beneficial effect on insulin sensitivity in normal as well as insulin resistant populations. A distinction should be made between the acute effects of exercise and genuine training effects. Up to two hours after exercise, glucose uptake is in part elevated due to insulin independent mechanisms, probably involving a contraction-induced increase in the amount of GLUT4 associated with the plasma membrane and T-tubules. However, a single bout of exercise can increase insulin sensitivity for at least 16 h post exercise in healthy as well as NIDDM subjects. Recent studies have accordingly shown that acute exercise also enhances insulin stimulated GLUT4 translocation. Increases in muscle GLUT4 protein content contribute to this effect, and in addition it has been hypothesized that the depletion of muscle glycogen stores with exercise plays a role herein. Physical training potentiates the effect of exercise on insulin sensitivity through multiple adaptations in glucose transport and metabolism. In addition, training may elicit favourable changes in lipid metabolism and can bring about improvements in the regulation of hepatic glucose output, which is especially relevant to NIDDM. It is concluded that physical training can be considered to play an important, if not essential role in the treatment and prevention of insulin insensitivity.
646 citations
TL;DR: The goal was to examine heart rate recovery as a predictor of long-term mortality in a population-based cohort of adults without evidence of cardiovascular disease who underwent submaximal exercise testing.
Abstract: Abnormal heart rate recovery after symptom-limited exercise is an important prognostic factor. This study found that even after submaximal exercise in patients in good cardiovascular health, abnorm...
TL;DR: It is demonstrated that exercise induces transient increases in transcription of metabolic genes in human skeletal muscle, and the findings suggest that the cumulative effects of transient rises in transcription during recovery from consecutive bouts of exercise may represent the underlying kinetic basis for the cellular adaptations associated with exercise training.
Abstract: Exercise training elicits a number of adaptive changes in skeletal muscle that result in an improved metabolic efficiency. The molecular mechanisms mediating the cellular adaptations to exercise tr...
TL;DR: This review considers four additional models that need to be considered when factors limiting either short duration, maximal or prolonged submaximal exercise are evaluated, and provides a broad overview of the physiological, metabolic and biomechanical factors that may limit exercise performance under different exercise conditions.
Abstract: A popular concept in the exercise sciences holds that fatigue develops during exercise of moderate to high intensity, when the capacity of the cardiorespiratory system to provide oxygen to the exercising muscles falls behind their demand inducing ‘‘anaerobic’’ metabolism. But this cardiovascular/anaerobic model is unsatisfactory because (i) a more rigorous analysis indicates that the first organ to be affected by anaerobiosis during maximal exercise would likely be the heart, not the skeletal muscles. This probability was fully appreciated by the pioneering exercise physiologists, A. V. Hill, A. Bock and D. B. Dill, but has been systematically ignored by modern exercise physiologists; (ii) no study has yet definitely established the presence of either anaerobiosis, hypoxia or ischaemia in skeletal muscle during maximal exercise; (iii) the model is unable to explain why exercise terminates in a variety of conditions including prolonged exercise, exercise in the heat and at altitude, and in those with chronic diseases of the heart and lungs, without any evidence for skeletal muscle anaerobiosis, hypoxia or ischaemia, and before The nature of the physiological and biochemical adaptations that occur in response to physical training has been extensively studied in humans and other mammals. This information is readily available and is likely to be well known to most exercise scientists (Saltin & Gollnick 1983, Holloszy & Coyle 1984). Similarly there is an extensive literature on the cellular mechanisms believed to cause the fatigue that develops during exercise (Fitts 1994). In contrast, fewer studies have evaluated the extent to which these adaptations explain the improvements * Based on Keynote addresses presented at the Fourth IOC World Congress on Sports Sciences, Monte-Carlo, Monaco, October 22‐26, 1997 and the IV Scandinavian Congress on Medicine and Science in Sports, Lahti, Finland, 5‐8 November 1998.
TL;DR: It follows that exhaustive whole-body VE elicits a mild cardiovascular exertion, and that neural as well as muscular mechanisms of fatigue may play a role.
Abstract: Summary Vibration exercise (VE) is a new neuromuscular training method which is applied in athletes as well as in prevention and therapy of osteoporosis. The present study explored the physiological mechanisms of fatigue by VE in 37 young healthy subjects. Exercise and cardiovascular data were compared to progressive bicycle ergometry until exhaustion. VE was performed in two sessions, with a 26 Hz vibration on a ground plate, in combination with squatting plus additional load (40% of body weight). After VE, subjectively perceived exertion on Borg’s scale was 18, and thus as high as after bicycle ergometry. Heart rate after VE increased to 128 min ‐1 , blood pressure to 132/ 52 mmHg, and lactate to 3AE 5m M. Oxygen uptake in VE was 48AE8% of VO2max in bicycle ergometry. After VE, voluntary force in knee extension was reduced by 9AE2%, jump height by 9AE1%, and the decrease of EMG median frequency during maximal voluntary contraction was attenuated. The reproducibility in the two VE sessions was quite good: for heart rate, oxygen uptake and reduction in jump height, correlation coefficients of values from session 1 and from session 2 were between 0AE67 and 0AE7. Thus, VE can be well controlled in terms of these parameters. Surprisingly, an itching erythema was found in about half of the individuals, and an increase in cutaneous blood flow. It follows that exhaustive whole-body VE elicits a mild cardiovascular exertion, and that neural as well as muscular mechanisms of fatigue may play a role.
TL;DR: Physical activity, including moderate-intensity exercise such as walking, is associated with substantial reduction in risk of total and ischemic stroke in a dose-response manner, and data indicate that physical activity was not significantly associated with subarachnoid hemorrhage or intracerebral hemorrhage.
Abstract: ContextPersuasive evidence has demonstrated that increased physical activity
is associated with substantial reduction in risk of coronary heart disease.
However, the role of physical activity in the prevention of stroke is less
well established.ObjectiveTo examine the association between physical activity and risk of total
stroke and stroke subtypes in women.Design and SettingThe Nurses' Health Study, a prospective cohort study of subjects residing
in 11 US states.SubjectsA total of 72,488 female nurses aged 40 to 65 years who did not have
diagnosed cardiovascular disease or cancer at baseline in 1986 and who completed
detailed physical activity questionnaires in 1986, 1988, and 1992.Main Outcome MeasureIncident stroke occurring between baseline and June 1, 1994, compared
among quintiles of physical activity level as measured by metabolic equivalent
tasks (METs) in hours per week.ResultsDuring 8 years (560,087 person-years) of follow-up, we documented 407
incident cases of stroke (258 ischemic strokes, 67 subarachnoid hemorrhages,
42 intracerebral hemorrhages, and 40 strokes of unknown type). In multivariate
analyses controlling for age, body mass index, history of hypertension, and
other covariates, increasing physical activity was strongly inversely associated
with risk of total stroke. Relative risks (RRs) in the lowest to highest MET
quintiles were 1.00, 0.98, 0.82, 0.74, and 0.66 (P
for trend=.005). The inverse gradient was seen primarily for ischemic stroke
(RRs across increasing MET quintiles, 1.00, 0.87, 0.83, 0.76, and 0.52; P for trend=.003). Physical activity was not significantly
associated with subarachnoid hemorrhage or intracerebral hemorrhage. After
multivariate adjustment, walking was associated with reduced risk of total
stroke (RRs across increasing walking MET quintiles, 1.00, 0.76, 0.78, 0.70,
and 0.66; P for trend=.01) and ischemic stroke (RRs
across increasing walking MET quintiles, 1.00, 0.77, 0.75, 0.69, and 0.60; P for trend=.02). Brisk or striding walking pace was associated
with lower risk of total and ischemic stroke compared with average or casual
pace.ConclusionThese data indicate that physical activity, including moderate-intensity
exercise such as walking, is associated with substantial reduction in risk
of total and ischemic stroke in a dose-response manner.
TL;DR: It is concluded that vagal modulation of heart period appears to be sensitive to the recent experience of persistent emotional stress, regardless of a person's level of physical fitness and disposition toward experiencing anxiety.
TL;DR: It is suggested that regular physical activity can at least in part prevent the age-induced endothelial dysfunction, probably the restoration of nitric oxide availability consequent to prevention of production of oxidative stress.
Abstract: Background—Aging is associated with increased cardiovascular risk and endothelial dysfunction. Since exercise can improve endothelium-dependent vasodilation, in the present study we tested whether long-term physical activity could prevent aging-related endothelial dysfunction. Methods and Results—In 12 young and elderly (age 26.9±2.3 and 62.9±5.8 years, respectively) healthy sedentary subjects and 11 young and 14 elderly matched athletes (age 27.5±1.9 and 66.4±6.1 years, respectively), we studied (with strain-gauge plethysmography) forearm blood flow modifications induced by intrabrachial acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 μg/100 mL per minute), an endothelium-dependent vasodilator, at baseline, during infusion of NG-monomethyl-l-arginine (L-NMMA) (100 μg/100 mL forearm tissue per minute), a nitric oxide–synthase inhibitor, vitamin C (8 mg/100 mL forearm tissue per minute), an antioxidant, and finally under simultaneous infusion of L-NMMA and vitamin C. The response to sodium nitroprusside (1, 2,...
TL;DR: Results from animal research seem to indicate that there are multiple analgesia systems, including opioid and non-opioid systems, and that properties of the exercise stressor are important in determining which analgesic system is activated during exercise.
Abstract: Over the past 20 years a number of studies have examined whether analgesia occurs following exercise. Exercise involving running and cycling have been examined most often in human research, with swimming examined most often in animal research. Pain thresholds and pain tolerances have been found to increase following exercise. In addition, the intensity of a given pain stimulus has been rated lower following exercise. There have been a number of different noxious stimuli used in the laboratory to produce pain, and it appears that analgesia following exercise is found more consistently for studies that used electrical or pressure stimuli to produce pain, and less consistently in studies that used temperature to produce pain. There is also limited research indicating that analgesia can occur following resistance exercise and isometric exercise. Currently, the mechanism(s) responsible for exercise-induced analgesia are poorly understood. Although involvement of the endogenous opioid system has received mixed support in human research, results from animal research seem to indicate that there are multiple analgesia systems, including opioid and non-opioid systems. It appears from animal research that properties of the exercise stressor are important in determining which analgesic system is activated during exercise.
TL;DR: Lifestyle modifications including bodyweight loss and physical activity provide health benefits and functional gains and should be promoted to increase insulin sensitivity and prevent glucose intolerance and type 2 diabetes mellitus in older adults.
Abstract: Insulin resistance, a reduction in the rate of glucose disposal elicited by a given insulin concentration, is present in individuals who are obese, and those with diabetes mellitus, and may develop with aging. Methods which are utilised to measure insulin sensitivity include the hyperinsulinaemic-euglycaemic and hyperglycaemic clamps and the intravenous glucose tolerance tests. Several hormones and regulatory factors affect insulin action and may contribute to the insulin resistance observed in obesity. In addition, abnormal free fatty acid metabolism plays an important role in insulin resistance and the abnormal carbohydrate metabolism seen in individuals who are obese or diabetic. Thus, the mechanisms underlying the development of insulin resistance are multifactorial, and also involve alterations of the insulin signalling pathway. Aging is associated with an increase in bodyweight and fat mass. Not only is abdominal fat associated with hyperinsulinaemia but visceral adiposity is correlated with insulin resistance as well. Modifications of the changes in body composition with aging by diet and exercise training could delay the onset of insulin resistance. Weight loss and aerobic and resistive exercise training result in losses of total body fat and abdominal fat. Several studies report that bodyweight loss increases insulin sensitivity and improves glucose tolerance. In addition, the insulin resistance observed in aged persons can be modified by physical training. Longitudinal studies indicate significant improvements in glucose metabolism with aerobic exercise training in middle-aged and older men and women. Moreover, the improvements in insulin sensitivity with resistive training are similar in magnitude to those achieved with aerobic exercise. The improvements in glucose metabolism after bodyweight loss and exercise training may in some cases be partially attributed to changes in body composition, including reductions in total and central body fat. Yet, additional changes in skeletal muscle, blood flow and other mechanisms likely interact to modify insulin resistance with exercise training. Lifestyle modifications including bodyweight loss and physical activity provide health benefits and functional gains and should be promoted to increase insulin sensitivity and prevent glucose intolerance and type 2 diabetes mellitus in older adults.
TL;DR: It is suggested that exercise can improve endurance, strength, gait, and function in chronically impaired, fall-prone elderly persons.
Abstract: Objectives. This randomized controlled trial studied the effects of a low- to moderate-intensity group exercise program on strength, endurance, mobility, and fall rates in fall-prone elderly men with chronic impairments. Methods. Fifty-nine community-living men (mean age � 74 years) with specific fall risk factors (i.e., leg weakness, impaired gait or balance, previous falls) were randomly assigned to a control group (n � 28) or to a 12-week group exercise program (n � 31). Exercise sessions (90 minutes, three times per week) focused on increasing strength and endurance and improving mobility and balance. Outcome measures included isokinetic strength and endurance, five physical performance measures, and self-reported physical functioning, health perception, activity level, and falls. Results. Exercisers showed significant improvement in measures of endurance and gait. Isokinetic endurance increased 21% for right knee flexion and 26% for extension. Exercisers had a 10% increase ( p � .05) in distance walked in six minutes, and improved ( p � .05) scores on an observational gait scale. Isokinetic strength improved only for right knee flexion. Exercise achieved no significant effect on hip or ankle strength, balance, self-reported physical functioning, or number of falls. Activity level increased within the exercise group. When fall rates were adjusted for activity level, the exercisers had a lower 3-month fall rate than controls (6 falls/1000 hours of activity vs 16.2 falls/1000 hours, p � .05). Discussion. These findings suggest that exercise can improve endurance, strength, gait, and function in chronically impaired, fall-prone elderly persons. In addition, increased physical activity was associated with reduced fall rates when adjusted for level of activity.
TL;DR: The decrease of the CRP base-line concentration after training suggests that intensive regular exercise has a systemic anti-inflammatory effect.
Abstract: An intense physical exercise induces an inflammatory reaction as demonstrated by the delayed increase in blood of acute phase proteins and among them of C-reactive protein (CRP). There is also evidence for a diminished acute phase reaction due to regular exercise suggesting a suppression of the inflammatory response through training. With this background CRP was measured by a sensitive enzyme immunoassay under resting conditions before and after 9 months of training in 14 subjects preparing for a marathon with the aim of studying the effect of training on the base-line CRP concentration. The mean distance run per week increased significantly from 31 +/- 9 km at the beginning to 53 +/- 15 km after 8 months of training (p < 0.01). The aerobic capacity rose significantly after training as demonstrated by the increase of running velocity during a maximal treadmill test from 3.82 +/- 0.29 m/s pre-training to 4.17 +/- 0.17 m/s post-training at a blood lactate concentration of 4 mmol/L (p < 0.01). In 10 of 12 runners base-line CRP was diminished after training in spite of a continuous increase of training intensity. The CRP median fell from 1.19 mg/L before to 0.82 mg/L after training (p < 0.05). Since intense physical exercise is known to be associated with an inflammatory reaction of muscles and tendons, the CRP decrease was unexpected. In 2 subjects the CRP concentration rose markedly because of a borrelia infection and a knee injury, respectively. These values were caused by a pathological condition and were not considered for the statistical evaluation. In 10 non-training control subjects the CRP median did not change significantly during the same 9 months period. The decrease of the CRP base-line concentration after training suggests that intensive regular exercise has a systemic anti-inflammatory effect. This is of particular interest with regard to several recent reports confering on the concentration of CRP in plasma a predictive value for the risk of cardiac infarction, venous thrombosis or stroke.
TL;DR: It appears plausible that muscular adaptation to physical exercise occurs without preceding muscle inflammation, and modes of stress other than eccentric cycling should therefore be evaluated as a myositis model in human.
Abstract: 1. A role of the immune system in muscular adaptation to physical exercise has been suggested but data from controlled human studies are scarce. The present study investigated immunological events in human blood and skeletal muscle by immunohistochemistry and flow cytometry after eccentric cycling exercise and multiple biopsies. 2. Immunohistochemical detection of neutrophil- (CD11b, CD15), macrophage- (CD163), satellite cell- (CD56) and IL-1beta-specific antigens increased similarly in human skeletal muscle after eccentric cycling exercise together with multiple muscle biopsies, or multiple biopsies only. 3. Changes in immunological variables in blood and muscle were related, and monocytes and natural killer (NK) cells appeared to have governing functions over immunological events in human skeletal muscle. 4. Delayed onset muscle soreness, serum creatine kinase activity and C-reactive protein concentration were not related to leukocyte infiltration in human skeletal muscle. 5. Eccentric cycling and/or muscle biopsies did not result in T cell infiltration in human skeletal muscle. Modes of stress other than eccentric cycling should therefore be evaluated as a myositis model in human. 6. Based on results from the present study, and in the light of previously published data, it appears plausible that muscular adaptation to physical exercise occurs without preceding muscle inflammation. Nevertheless, leukocytes seem important for repair, regeneration and adaptation of human skeletal muscle.
TL;DR: Compared with untrained persons exercising at the same absolute intensity, persons who have undergone endurance training have greater fat oxidation during exercise without increased lipolysis, and available evidence suggests that the training-induced increase in fat oxidation is due primarily to increased oxidation of non-plasma-derived fatty acids, perhaps from intramuscular triacylglycerol stores.
TL;DR: Impaired balance and gait are the 2 most significant risk factors for limited mobility and falls in the elderly and it is important to understand the effects of aging and exercise on these risk factors.
Abstract: The elderly population is growing both in size and in proportion of the total population. The costs to the community of the elderly being in poor health are also growing proportionately. The beneficial effects of exercise on various physiological and psychological parameters in the elderly have been well established. The effects of exercise on the mobility and independence of the elderly are also of primary concern, their maintenance being an important exercise goal. Impaired balance and gait are the 2 most significant risk factors for limited mobility and falls in the elderly. It is important to understand the effects of aging and exercise on these risk factors.
TL;DR: The principles of exercise prescription for persons with chronic diseases and disabilities should place more emphasis on the patient’s clinical status and, as a result, the exercise mode, intensity, frequency and duration are usually modified according to their clinical condition.
Abstract: Exercise prescription principles for persons without chronic disease and/or disability are based on well developed scientific information. While there are varied objectives for being physically active, including enhancing physical fitness, promoting health by reducing the risk for chronic disease and ensuring safety during exercise participation, the essence of the exercise prescription is based on individual interests, health needs and clinical status, and therefore the aforementioned goals do not always carry equal weight. In the same manner, the principles of exercise prescription for persons with chronic disease and/or disability should place more emphasis on the patient's clinical status and, as a result, the exercise mode, intensity, frequency and duration are usually modified according to their clinical condition. Presently, these exercise prescription principles have been scientifically defined for clients with coronary heart disease. However, other diseases and/or disabilities have been studied less (e.g. renal failure, cancer, chronic fatigue syndrome, cerebral palsy). This article reviews these issues with specific reference to persons with chronic diseases and disabilities.
TL;DR: It is suggested that testosterone and resistance exercise promote gains in body weight, muscle mass, muscle strength, and lean body mass in HIV-infected men with weight loss and low testosterone levels.
Abstract: ContextPrevious studies of testosterone supplementation in HIV-infected men
failed to demonstrate improvement in muscle strength. The effects of resistance
exercise combined with testosterone supplementation in HIV-infected men are
unknown.ObjectiveTo determine the effects of testosterone replacement with and without
resistance exercise on muscle strength and body composition in HIV-infected
men with low testosterone levels and weight loss.Design and SettingPlacebo-controlled, double-blind, randomized clinical trial conducted
from September 1995 to July 1998 at a general clinical research center.ParticipantsSixty-one HIV-infected men aged 18 to 50 years with serum testosterone
levels of less than 12.1 nmol/L (349 ng/dL) and weight loss of 5% or more
in the previous 6 months, 49 of whom completed the study.InterventionsParticipants were randomly assigned to 1 of 4 groups: placebo, no exercise
(n = 14); testosterone enanthate (100 mg/wk intramuscularly), no exercise
(n = 17); placebo and exercise (n = 15); or testosterone and exercise (n =
15). Treatment duration was 16 weeks.Main Outcome MeasuresChanges in muscle strength, body weight, thigh muscle volume, and lean
body mass compared among the 4 treatment groups.ResultsBody weight increased significantly by 2.6 kg (P<.001)
in men receiving testosterone alone and by 2.2 kg (P
= .02) in men who exercised alone but did not change in men receiving placebo
alone (−0.5 kg; P = .55) or testosterone and
exercise (0.7 kg; P = .08). Men treated with testosterone
alone, exercise alone, or both experienced significant increases in maximum
voluntary muscle strength in leg press (range, 22%-30%), leg curls (range,
18%-36%), bench press (range, 19%-33%), and latissimus pulls (range, 17%-33%).
Gains in strength in all exercise categories were greater in men assigned
to the testosterone-exercise group or to the exercise-alone group than in
those assigned to the placebo-alone group. There was a greater increase in
thigh muscle volume in men receiving testosterone alone (mean change, 40
cm3; P<.001 vs zero change)
or exercise alone (62 cm; P = .003) than in men receiving placebo alone (5
cm3; P = .70). Average lean body mass increased by 2.3 kg (P = .004) and 2.6 kg (P<.001),
respectively, in men who received testosterone alone or testosterone and exercise
but did not change in men receiving placebo alone (0.9 kg; P = .21).Hemoglobin levels increased in men receiving testosterone
but not in those receiving placebo.ConclusionOur data suggest that testosterone and resistance exercise promote gains
in body weight, muscle mass, muscle strength, and lean body mass in HIV-infected
men with weight loss and low testosterone levels. Testosterone and exercise
together did not produce greater gains than either intervention alone.
TL;DR: There is no evidence that habitual exercise increases protein requirements; indeed protein metabolism may become more efficient as a result of training.
Abstract: Sustained dynamic exercise stimulates amino acid oxidation, chiefly of the branched-chain amino acids, and ammonia production in proportion to exercise intensity; if the exercise is intense enough, there is a net loss of muscle protein (as a result of decreased protein synthesis, increased breakdown, or both); some of the amino acids are oxidized as fuel, whereas the rest provide substrates for gluconeogenesis and possibly for acid-based regulation. Protein balance is restored after exercise, but no hypertrophy occurs with habitual dynamic exercise. Resistance exercise causes little change in amino acid oxidation but probably depresses protein synthesis and elevates breakdown acutely. After exercise, protein synthesis rebounds for
TL;DR: T treadmill running produces both positive training adaptations and potentially negative adaptations that are indicative of chronic stress and that these changes could potentially impact other measures of interest.
Abstract: Exercise training produces a vast array of physiological adaptations, ranging from changes in metabolism to muscle mitochondrial biogenesis. Researchers studying the physiological effects of exercise often use animal models that employ forced exercise regimens that include aversive motivation, which could activate the stress response. This study examined the effect of forced treadmill running (8 wk) on several physiological systems that are sensitive to training and stress. Forced treadmill running produced both positive and negative physiological adaptations. Indicative of positive training adaptations, exercised male Sprague-Dawley rats had a decrease in body weight gain and an increase in muscle citrate synthase activity compared with sedentary controls. In contrast, treadmill running also resulted in the potentially negative adaptations of adrenal hypertrophy, thymic involution, decreased serum corticosteroid binding globulin, elevated lymphocyte nitrite concentrations, suppressed lymphocyte proliferation, and suppressed antigen-specific IgM. Such alterations in neuroendocrine tissues and immune responses are commonly associated with chronic stress. Thus treadmill running produces both positive training adaptations and potentially negative adaptations that are indicative of chronic stress. Researchers employing forced activity need to be aware that this type of exercise procedure also produces physiological adaptations indicative of chronic stress and that these changes could potentially impact other measures of interest.
TL;DR: In patients with flow limitation, inspiratory capacity appears as the best predictor of exercise tolerance, reflecting the presence of dynamic hyperinflation.
Abstract: Expiratory flow limitation promotes dynamic hyperinflation during exercise in chronic obstructive pulmonary disease (COPD) patients with a consequent reduction in inspiratory capacity (IC), limiting their exercise tolerance. Therefore, the exercise capacity of patients with tidal expiratory flow limitation (FL) at rest should depend on the magnitude of IC. The presented study was designed to evaluate the role of FL on the relationship between resting IC, other respiratory function variables and exercise performance in COPD patients. Fifty-two patients were included in the study. Negative expiratory pressure (NEP) uptake (VO2,max) were measured during an incremental symptom-limited cycle exercise. Twenty-nine patients were FL at rest. The IC was normal in all non-FL patients, while in most FL subjects it was decreased. Both WRmax and VO2,max were lower in FL patients (p<0.001, each). A close relationship of WRmax and O2,max to IC was found (r=0.73 and 0.75, respectively; p<0.0001, each). In the whole group, stepwise regression analysis selected IC and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (% predicted) as the only significant contributors to exercise tolerance. Subgroup analysis showed that IC was the sole predictor in FL patients, and FEV1/FVC in non-FL patients. Detection of flow limitation provides useful information on the factors that influence exercise capacity in chronic obstructive pulmonary disease patients. Accordingly, in patients with flow limitation, inspiratory capacity appears as the best predictor of exercise tolerance, reflecting the presence of dynamic hyperinflation.
TL;DR: If a combined dietary and exercise intervention would result in significant weight loss in older obese adults with knee osteoarthritis and to compare the effects of exercise plus dietary therapy with exercise alone on gait, strength, knee pain, biomarkers of cartilage degradation, and physical function.
Abstract: Objective The purposes of this pilot study were to determine if a combined dietary and exercise intervention would result in significant weight loss in older obese adults with knee osteoarthritis, and to compare the effects of exercise plus dietary therapy with exercise alone on gait, strength, knee pain, biomarkers of cartilage degradation, and physical function. Design Single-blind, two-arm, randomized clinical trial conducted for 24 weeks. Setting A university health and exercise science center. Participants Twenty-four community-dwelling obese older adults aged > or = 60 years, body mass index > or = 28, knee pain, radiographic evidence of knee osteoarthritis, and self-reported physical disability. Intervention Randomization into two groups: exercise and diet (E&D) and exercise alone (E). Exercise consisted of a combined weight training and walking program for 1 hour three times per week. The dietary intervention included weekly sessions with a nutritionist utilizing cognitive-behavior modification to change dietary habits to reach a group goal of an average weight loss of 15 lb (6.8 kg) over 6 months. Measurements All measurements were conducted at baseline and 3 and 6 months, except for synovial fluid analysis, which was obtained only at baseline and 6 months. In addition, weight was measured weekly in the E&D group. Physical disability and knee pain were measured by self-report and physical performance was measured using the 6-minute walk and stair climb tasks. Biomechanical testing included kinetic and kinematic analysis of gait and isokinetic strength testing. Synovial fluid was analyzed for levels of total proteoglycan, keratan sulfate, and interleukin-1 beta. Results Twenty-one of the 24 participants completed the study, with one dropout in the E&D group and two in the E group. The E&D group lost a mean of 18.8 lb (8.5 kg) at 6 months compared with 4.0 lb (1.8 kg) in the E group (P = .01). Significant improvements were noted in both groups in self-reported disability and knee pain intensity and frequency as well as in physical performance measures. However, no statistical differences were found between the two groups at 6 months in knee pain scores or self-reported performance measures of physical function. There was no difference in knee strength between the groups, with both groups showing modest improvements from baseline to 6 months. At 6 months, the E&D group had a significantly greater loading rate (P = .03) and maximum braking force (P = .01) during gait. There were no significant between-group differences in the other biomechanical measures. Synovial fluid samples were obtainable at both baseline and 6 months in eight participants (four per group). The level of keratan sulfate decreased similarly in both groups from an average baseline of 96.8 +/- 37.1 to 71.5 +/- 23 ng/microg total proteoglycan. The level of IL-1 decreased from 25.3 +/- 9.8 at baseline to 8.3 +/- 6.1 pg/mL. The decrease in IL-1 correlated with the change in pain frequency (r = -0.77, P = .043). Conclusions Weight loss can be achieved and sustained over a 6-month period in a cohort of older obese persons with osteoarthritis of the knee through a dietary and exercise intervention. Both exercise and combined weight loss and exercise regimens lead to improvements in pain, disability, and performance. Moreover, the trends in the biomechanical data suggest that exercise combined with diet may have an additional benefit in improved gait compared with exercise alone. A larger study is indicated to determine if weight loss provides additional benefits to exercise alone in this patient population.