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PubMedDate not supplied

Exercise as a treatment for chronic low back pain.

BACKGROUND CONTEXT: Exercise is a widely prescribed treatment for chronic low back pain, with demonstrated effectiveness for improving function and work. PURPOSE: The goal of this article is to review several key aspects about the safety and efficacy of exercise that may help clinicians understand its utility in treating chronic back pain. STUDY DESIGN/SETTING: A computerized literature search of MEDLINE was conducted using "exercise," "fitness," "back pain," "backache" and "rehabilitation" as search words. Identified abstracts were scanned, and useful articles were acquired for further review. Additional references were acquired through the personal collections of research papers possessed by the authors and by reviewing prior review articles on this subject. These final papers were scrutinized for data relevant to the key aspects about exercise covered in this article. RESULTS: For people with acute, subacute or chronic low back pain, there is no evidence that exercise increases the risk of additional back problems or work disability. To the contrary, current medical literature suggests that exercise has either a neutral effect or may slightly reduce risk of future back injuries. Exercise can be prescribed for patients with chronic low back pain with three distinct goals. The first and most obvious goal is to improve or eliminate impairments in back flexibility and strength, and improve performance of endurance activities. There is a large body of evidence confirming that this goal can be accomplished for a majority of patients with chronic low back pain. The second goal of exercise is to reduce the intensity of back pain. Most studies of exercise have noted overall reduction in back pain intensity that ranges from 10% to 50% after exercise treatment. The third goal of exercise is to reduce back pain-related disability through a process of desensitization of fears and concerns, altering pain attitudes and beliefs and improving affect. The mechanisms through which exercise can accomplish this goal have been the subject of substantial research. CONCLUSIONS: Exercise is safe for individuals with back pain, because it does not increase the risk of future back injuries or work absence. Substantial evidence exists supporting the use of exercise as a therapeutic tool to improve impairments in back flexibility and strength. Most studies have observed improvements in global pain ratings after exercise programs, and many have observed that exercise can lessen the behavioral, cognitive, affect and disability aspects of back pain syndromes.

Exercise Therapy↗

PubMed2000

Physiological models to understand exercise fatigue and the adaptations that predict or enhance athletic performance.

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 there is full activation of the total skeletal muscle mass, and (iv) cardiovascular and other measures believed to relate to skeletal muscle anaerobiosis, including the maximum oxygen consumption (VO2 max) and the "anaerobic threshold", are indifferent predictors of exercise capacity in athletes with similar abilities. This review considers four additional models that need to be considered when factors limiting either short duration, maximal or prolonged submaximal exercise are evaluated. These additional models are: (i) the energy supply/energy depletion model; (ii) the muscle power/muscle recruitment model; (iii) the biomechanical model and (iv) the psychological model. By reviewing features of these models, this review provides a broad overview of the physiological, metabolic and biomechanical factors that may limit exercise performance under different exercise conditions. A more complete understanding of fatigue during exercise, and the relevance of the adaptations that develop with training, requires that the potential relevance of each model to fatigue under different conditions of exercise must be considered.

Adaptation, Physiological↗

PubMed2001

Effects of moderate and high glycemic index meals on metabolism and exercise performance.

The purpose of this study was to determine whether pre-exercise ingestion of meals with moderate and high glycemic indexes (GI) affects glucose availability during exercise and exercise performance time. Six male volunteers (22 +/- 1 years; 80.4 +/- 3.7 kg; VO(2peak), 54.3 +/- 1.2 ml. kg(-1). min(-1)) ingested 75 g of carbohydrate in the form of 2 different breakfast cereals, rolled oats (moderate GI, approximately 61; MOD-GI) or puffed rice (high GI, approximately 82; HI-GI), combined with 300 mL of water; or water alone (control). The trials were randomized, and the meals were ingested 45 minutes before the subjects performed cycling exercise (60% VO(2peak)) to exhaustion. Venous blood samples were drawn to measure glucose, free fatty acids (FFAs), glycerol, insulin (INS), epinephrine (EPI) and norepinephrine (NE) concentrations. A muscle biopsy specimen was obtained from the vastus lateralis before the meal and immediately after exercise for glycogen determination. Before exercise, both test meals elicited significant (P <.05) hyperglycemia and hyperinsulinemia compared with control. The glycemic response was higher (P <.05) at the start of exercise after the HI-GI meal than after the control. During exercise, plasma glucose levels were higher (P <.05) at 60 (5.2 +/- 0.1, 4.2 +/- 0.2, and 4.6 +/- 0.1 mmol. L(-1)) and 90 (4.8 +/- 0.1, 4.1 +/- 0.1, and 4.3 +/- 0.1 mmol. L(-1)) minutes after the MOD-GI meal than after either the HI-GI or control. Total carbohydrate oxidation was greater (P <.05) during the MOD-GI trial than in control and was directly correlated with exercise performance time (r =.95, P <.0001). Pre-exercise plasma FFA levels were suppressed (P <.05) 30 and 45 minutes after ingestion of the HI-GI meal and 45 minutes after the MOD-GI meal compared with control. At 30, 60, and 120 minutes of exercise, FFAs remained suppressed (P <.05) for both test meals compared with control. At exhaustion, plasma glucose, INS, FFA, glycerol, EPI, and NE levels and muscle glycogen use were not different for all trials. Exercise time was prolonged (P <.05) after the MOD-GI meal compared with control, but the HI-GI trial was not different from control (MOD-GI, 165 +/- 11; HI-GI, 141 +/- 8; control, 134 +/- 13 minutes). Thus, in contrast to the HI-GI meal or control, the MOD-GI breakfast cereal ingested 45 minutes before exercise enhanced performance time, maintained euglycemia for a longer period during exercise, and resulted in greater total carbohydrate oxidation during the exercise bout. We conclude that a MOD-GI meal provides a significant performance and metabolic advantage when consumed 45 minutes before exercise.

Adult↗

PubMed2006

Arterial stiffness and baroreflex sensitivity following bouts of aerobic and resistance exercise.

We examined arterial stiffness, baroreflex sensitivity (BRS), and systolic arterial pressure (SAP) variability after an acute bout of aerobic exercise compared to resistance exercise. We hypothesized that arterial stiffness would be reduced after aerobic exercise, while it would be increased after resistance exercise, and these alterations would be associated with differential changes in BRS and SAP variability. Arterial stiffness, BRS, and SAP variability were assessed before and 20 min after a bout of aerobic exercise and resistance exercise in 13 male participants. Pulse wave velocity (PWV) was used to measure central (carotid-femoral) and peripheral (femoral-dorsalis pedis) arterial stiffness. BRS was derived via the sequence technique. Spectral decomposition of beat-to-beat SAP variability was used as an estimate of sympathetic vasomotor tone. A mode-by-time interaction (p < 0.001) was detected for central PWV, due to an increase in PWV (p < 0.05) following resistance exercise and a decrease in PWV following aerobic exercise (p < 0.05). A mode-by-time interaction was also detected for peripheral PWV (p < 0.05), due to a decrease in peripheral PWV following aerobic exercise (p < 0.05) with no change following resistance exercise. BRS was significantly lower following resistance compared with aerobic exercise (p < 0.004). SAP variability increased following resistance exercise (p < 0.05) but there was no interaction. In conclusion, aerobic exercise decreased both central and peripheral arterial stiffness, while resistance exercise significantly increased central arterial stiffness only. BRS was reduced after both bouts of exercise, but significantly greater reductions were seen following resistance exercise.

Adult↗

PubMed1996

Determinants of exercise capacity in patients with coronary artery disease and mild to moderate systolic dysfunction. Role of heart rate and diastolic filling abnormalities.

BACKGROUND: To test the hypothesis that diastolic filling abnormalities are an important cause of exercise limitation in some patients with coronary artery disease we assessed the factors limiting exercise capacity in a group of patients with coronary artery disease in whom exercise limitation was greater than expected from the degree of resting left ventricular systolic dysfunction. METHODS AND RESULTS: We assessed the relationship between exercise capacity (maximal oxygen consumption) during erect cycle ergometry, heart rate, radionuclide indices of left ventricular systolic function (ejection fraction) and diastolic filling (peak filling rate, and time to peak filling) during semi-erect cycle ergometry in 20 patients (15 male, five female) who were aged 42-72 years (mean 61 years) and had angiographically proven coronary artery disease and evidence of reversible myocardial ischaemia on thallium scintigraphy. All patients exhibited marked exercise limitation (maximal oxygen consumption 8.7- 22.4 ml.min-1.kg-1--mean 15.9 ml.kg-1.min-1, which was 61.1 +/- 16% of age and gender predicted maximum) due to breathlessness or fatigue rather than angina, in spite of a mean ejection fraction for the group of 46.5% (range 30-67%). We also compared the diastolic filling characteristics of these patients during exercise with 10 healthy controls (age 38-66, mean 58 years; eight male, two female). Comparing diastolic filling characteristics, peak filling rate was higher and time to peak filling shorter both at rest and at peak exercise in controls than patients (peak filling rate 3.1 +/- 0.5 vs 2.2 +/- 0.9 EDV.s-1, P = 0.01 at rest and 8.3 +/- 0.8 vs 5.2 +/- 1.9 EDV.s-1, P < 0.0001 on exercise; time to peak filling 115.2 +/- 29.8 vs 228.9 +/- 71.7 ms, P < 0.0001 at rest and 52.8 +/- 16.2 vs 139.6 +/- 44.8 ms, P < 0.0001 on exercise respectively). On univariate analysis in the patients studied, maximal oxygen consumption was correlated with peak heart rate (r = 0.45 P = 0.04), peak exercise time to peak filling (r = -0.85 P < 0.0001), peak exercise peak filling time rate (r = 0.51 P = 0.019), and the relative increase in cardiac output i.e. cardiac output peak/cardiac output rest (r = 0.58, P = 0.008). There was no correlation between maximal oxygen consumption and resting indices of diastolic filling (peak filling rate and time to peak filling) or with resting or peak exercise ejection fraction. On multiple regression analysis, only peak exercise time to peak filling was significantly related to maximal oxygen consumption. CONCLUSION: We have observed a strong correlation between exercise capacity and indices of exercise left ventricular diastolic filling, and have confirmed previous studies showing a poor correlation with resting and exercise indices of systolic function and resting diastolic filling, in patients with coronary artery disease.

Adult↗

PubMed2004

Effectiveness of exercise in management of fibromyalgia.

PURPOSE OF REVIEW: Exercise was established as an integral part of the nonpharmacological treatment of fibromyalgia approximately 20 years ago. Since then many studies have investigated the effects of exercise-either alone or in combination with other interventions. This review will discuss the benefits of exercise alone and provide practical suggestions on how patients can exercise without causing a long-term exacerbation of their pain. RECENT FINDINGS: Short-term exercise programs for individuals with fibromyalgia have consistently improved physical function, especially physical fitness, and reduced tenderpoint pain. Exercise has also produced improvements in self-efficacy. These effects can persist for periods of up to 2 years but may require participants to continue to exercise. Most exercise studies have examined the effects of moderately intense aerobic exercise. Only in the past 2 years have muscle-strengthening programs, in isolation, been evaluated. To be well tolerated, exercise programs must start at a level just below the capacity of the participants and then progress slowly. Even with these precautions, exercise may still produce tolerable, short-term increases in pain and fatigue that should abate within the first few weeks of exercising. SUMMARY: Future studies should investigate the possible benefits of low-intensity exercise and test strategies that may enhance long-term compliance with exercise. Individuals with fibromyalgia also need to be able to access community exercise programs that are appropriate for them. This may require community instructors to receive instruction on exercise prescription and progression for individuals with fibromyalgia.

Exercise Therapy↗

PubMedDate not supplied

Self-efficacy, psychosocial factors, and exercise behavior in traditional versus modified cardiac rehabilitation.

BACKGROUND: Self-efficacy and social support are established determinants of exercise adherence and have potential usefulness for tailoring independent exercise regimens for cardiac patients. Highly supervised traditional cardiac rehabilitation programs may be a barrier for independent exercise self-efficacy in low - and moderate-risk patients. PURPOSE: The authors evaluated changes in psychosocial measures including self-efficacy and social support in 80 cardiac patients with low to moderate risk randomized to a traditional cardiac rehabilitation protocol (TP) or modified protocol (MP). These measures also were assessed for their potential to predict subsequent exercise behavior. METHODS: The TP (n = 38) emphasized a supervised exercise regimen and included continuous electrocardiogram (ECG) monitoring for 3 months. The lower cost MP (n = 42) emphasized independent exercise and included group education/support meetings, and gradually weaned patients from continuous ECG monitoring and direct medical supervision. RESULTS: Repeated measures analyses of variance indicated that MP patients had higher levels of self-efficacy for independent exercise without continuous ECG monitoring (P < .05). No other protocol differences were found. Multiple regression analyses using the pooled sample (excluding dropouts) indicated that self-efficacy for independent exercise was the only significant predictor of exercise over 6 months (R2=.28 [adjusted R2= .221 P < .01). In contrast to previous reports, social support for exercise was not a significant predictor of exercise behavior. CONCLUSIONS: These findings suggest cardiac rehabilitation programs for low- and moderate-risk patients should emphasize educational and patient monitoring methods that promote patient self-efficacy for independent exercise. Programs that emphasize highly supervised exercise including longer term use of continuous ECG monitoring may impair self-efficacy for independent exercise. Longer-term studies are needed to fully determine the value of using psychosocial measures for designing individualized exercise programs and predicting long-term exercise behavior in cardiac patients.

Aged↗

PubMedDate not supplied

Predictors of women's exercise maintenance after cardiac rehabilitation.

PURPOSE: Less than 50% of persons who participate in cardiac rehabilitation (CR) programs maintain an exercise regimen for as long as 6 months after completion. This study was conducted to identify factors that predict women's exercise following completion of a CR program. METHODS: In this prospective, descriptive study, a convenience sample of 60 women were recruited at completion of a phase II CR program. Exercise was measured using a heart rate wristwatch monitor over 3 months. Predictor variables collected at the time of the subjects' enrollment were age, body mass index, cardiac functional status, comorbidity, muscle or joint pain, motivation, mood state, social support, self-efficacy, perceived benefits or barriers, and prior exercise. RESULTS: Of women, 25% did not exercise at all following completion of a CR program and only 48% of the subjects were exercising at 3 months. Different predictors were found of the various dimensions of exercise maintenance. Predictors of exercise frequency were comorbidity and instrumental social support. Instrumental social support was the only predictor of exercise persistence. Comorbidity was the only predictor of exercise intensity. The only predictor of the total amount of exercise was benefits or barriers. CONCLUSIONS: Interventions aimed at increasing women's exercise should focus on increasing their problem-solving abilities to reduce barriers to exercise and increase social support by family and friends. Because comorbidity was a significant predictor of exercise, women should be encouraged to use exercise techniques that reduce impact on muscles and joints (eg, swimming) or exercising for short periods several times a day.

Adult↗

PubMed1996

Adaptations to daily exercise in hot and humid ambient conditions in trained thoroughbred horses.

The objectives of this study were to: 1) determine the effects of heat and high relative humidity (RH) on the clinical and physiological responses of horses during and after daily exercise training and 2) determine whether repeated exposure to, and exercise in, the heat would result in improved thermal tolerance (heat acclimation). Six trained Thoroughbred horses completed 1 h of submaximal exercise in cool, dry conditions (CD) and during a daily 4 h period of exposure to high heat and humidity (HH, room temperature = 33-35 degrees C, RH = 80-85%) for 22 days. Rectal temperature (Tre) and heart rate (HR) were measured before, during and after exercise and respiratory rate (RR) was measured before exercise and during a 2 h recovery. In HH, the rate of rise in Tre was significantly higher than in CD. However, by HH Day 5, Tre before, during and after exercise was significantly lower than on HH Day 1. The day-to-day decrease in Tre during exercise was reflected in significant decreases in heat storage following exercise by HH Day 10 (910 +/- 47 kcal) when compared to HH Day 1 (1211 +/- 75 kcal). At rest, RR was initially higher in HH than CD, and a further increase in pre-exercise RR from HH Day 1 to Day 10 may have contributed to the lower pre-exercise Tre. Recovery RR was higher after HH Day 1 and was associated with a lower end-of-exercise HR did not change in the 1 h before exercise in CD and did not differ from HH Days 1-22. By HH Day 10, mean HR during the latter part of exercise was lower than HH Day 1 and was not different from pre-exercise by 60 min of recovery. Pre-exercise body mass did not change during the 3 wk period and the decrease in body mass that occurred during the 4 h training period was significantly attenuated by HH Day 15 (9.8 +/- 0.8 kg) when compared to HH Day 1 (12.5 +/- 0.8 kg). Over the 3 week period of HH, mean 24 h water consumption increased from 26.0 +/- 2.1 litres to 39.5 +/- 3.2 litres, largely reflecting a 2-fold increase in water intake during the 4 h period of heat exposure. It is concluded that 3 weeks of daily exposure to, and exercise in, hot and humid ambient conditions resulted in a progressive reduction in thermal and cardiovascular strain. Furthermore, the reported physiological adaptations are consistent with an improved thermal tolerance (heat acclimation).

Adaptation, Physiological↗

PubMed1997

Exercise-induced increase in serum interleukin-6 in humans is related to muscle damage.

1. This study was performed to test the hypothesis that the exercise-induced increase in circulating cytokine levels is associated with muscle damage. Nine healthy young male subjects performed two high-intensity bicycle exercise trials separated by two weeks. The first trial consisted of 30 min of normal bicycle exercise (concentric exercise), whereas the second consisted of 30 min of braking with reversed revolution (eccentric exercise). The work loads were chosen to give the same increases in heart rate and catecholamine levels in the blood during each trial. 2. Significant increases (P < 0.05) in plasma concentration of creatine kinase (CK), aspartate aminotransferase and alanine aminotransferase were observed only after the eccentric exercise. Furthermore, the level of interleukin-6 (IL-6) in serum increased significantly after the eccentric exercise and was significantly correlated to CK concentration in the following days, whereas no significant changes were found after the concentric exercise. 3. The total concentration of lymphocytes increased significantly (P < 0.05) as a result of eccentric compared with concentric exercise. This was mainly due to a significantly more pronounced recruitment of natural killer (NK) cells and CD8 positive cells (CD8+ cells) during the eccentric trial. However, no significant differences between the two types of work were found in regard to the circulating concentration of monocytes. The concentration of neutrophils was only significantly increased 2 h after the concentric exercise. 4. The finding that high-intensity eccentric exercise caused a more pronounced increase in the plasma level of IL-6, compared with concentric exercise, supports the hypothesis that the post-exercise cytokine production is related to skeletal muscle damage. The fact that no differences between eccentric and concentric exercise were found in the recruitment of most blood mononuclear cell subsets to the blood supports the hypothesis that the exercise-induced increase in plasma catecholamines is a major determinant of the mobilization of these cells into the blood. However, as eccentric exercise caused a more pronounced increase in the concentration of NK cells and CD8+ cells, factors involved in muscle damage may also contribute to the recruitment of these cells.

Adult↗

PubMed1989

Adenine nucleotide degradation in human skeletal muscle during prolonged exercise.

Eight healthy men cycled at a work load corresponding to approximately 70% of maximal O2 uptake (VO2max) to fatigue (exercise I). Exercise to fatigue at the same work load was repeated after 75 min of rest (exercise II). Exercise duration averaged 65 and 21 min for exercise I and II, respectively. Muscle (quadriceps femoris) content of glycogen decreased from 492 +/- 27 to 92 +/- 20 (SE) mmol/kg dry wt and from 148 +/- 17 to 56 +/- 17 (SE) mmol/kg dry wt during exercise I and II, respectively. Muscle and blood lactate were only moderately increased during exercise. The total adenine nucleotide pool (TAN = ATP + ADP + AMP) decreased and inosine 5'-monophosphate (IMP) increased in the working muscle during both exercise I (P less than 0.001) and II (P less than 0.01). Muscle content of ammonia (NH3) increased four- and eight-fold during exercise I and II, respectively. The working legs released NH3, and plasma NH3 increased progressively during exercise. The release of NH3 at the end of exercise II was fivefold higher than that at the same time point in exercise I (P less than 0.001, exercise I vs. II). It is concluded that submaximal exercise to fatigue results in a breakdown of the TAN in the working muscle through deamination of AMP to IMP and NH3. The relatively low lactate levels demonstrate that acidosis is not a necessary prerequisite for activation of AMP deaminase. It is suggested that the higher average rate of AMP deamination during exercise II vs. exercise I is due to a relative impairment of ATP resynthesis caused by the low muscle glycogen level.

Adenine Nucleotides↗

PubMed2005

Diet and exercise training restore blood pressure and vasodilatory responses during physiological maneuvers in obese children.

BACKGROUND: The effects of diet and diet plus exercise training on muscle vasodilatation during physiological maneuvers in obese children are unknown. We tested the hypothesis that (1) blood pressure (BP) and forearm vascular conductance (FVC) responses during handgrip exercise and mental stress would be altered in obese children and (2) diet plus exercise training would restore BP and FVC responses during exercise and mental stress in obese children. METHODS AND RESULTS: Thirty-nine obese children (aged 10+/-0.2 years) were randomly divided into 2 groups: diet plus exercise training (n=21; body mass index [BMI]=28+/-0.5 kg/m2) and diet (n=18; BMI=30+/-0.4 kg/m2). Ten age-matched lean control children (BMI=17+/-0.5 kg/m2) were also studied. Forearm blood flow was measured by venous occlusion plethysmography. BP was monitored noninvasively. Handgrip exercise was performed at 30% maximal voluntary contraction for 3 minutes. Stroop color word test was performed for 4 minutes. Baseline BP was significantly higher and FVC was significantly lower in obese children. During exercise and mental stress, BP responses were significantly higher and FVC responses were significantly lower in obese children. Diet and diet plus exercise training significantly reduced body weight. Diet and diet plus exercise training significantly decreased BP levels during exercise and mental stress. Diet plus exercise training, in contrast to diet alone, significantly increased FVC responses during exercise (3.7+/-0.3 versus 5.6+/-0.4 U; P=0.01) and mental stress (3.5+/-0.5 versus 4.5+/-0.4 U; P=0.02). After diet plus exercise training, BP and FVC responses during exercise and mental stress were similar between obese children and the control group. CONCLUSIONS: Obesity exacerbates BP responses and impairs FVC responses during exercise and mental stress in children. Diet and exercise training restore BP and FVC responses in obese children.

Blood Pressure↗

PubMed1992

Deficient acceleration of left ventricular relaxation during exercise after heart transplantation.

BACKGROUND: The exercise-induced rise in left ventricular filling pressures after cardiac transplantation is considered to be the result of a blunted heart rate response, of elevated venous return, and of unfavorable passive late-diastolic properties of the cardiac allograft. In contrast to passive late-diastolic left ventricular properties, the effect of left ventricular relaxation on the exercise-induced rise in left ventricular filling pressures of the cardiac allograft has not yet been studied. In the present study, the response of left ventricular relaxation to exercise was investigated in transplant recipients and compared with left ventricular relaxation observed in normal control subjects exercised to the same heart rate. Moreover, the response of left ventricular relaxation of the cardiac allograft to beta-adrenoreceptor stimulation, to reduced left ventricular afterload, and to increased myocardial activator calcium was investigated by infusion of dobutamine and of nitroprusside and by postextrasystolic potentiation. METHODS AND RESULTS: Twenty-seven transplant recipients were studied 1 year (n = 17), 2 years (n = 7), 3 years (n = 2), and 4 years (n = 1) after transplantation. All patients were free of rejection and of significant graft atherosclerosis at the time of study. Tip-micromanometer left ventricular pressure recordings and cardiac hemodynamics were obtained at rest, during supine bicycle exercise stress testing (n = 27), during dobutamine infusion at a heart rate matching the heart rate at peak exercise (n = 8), during nitroprusside infusion (n = 9), and after postextrasystolic potentiation (n = 10). Tip-micromanometer left ventricular pressure recordings were also obtained in a normal control group (n = 9) at rest and during supine bicycle exercise stress testing to a heart rate, which matched the heart rate of the transplant recipient group at peak exercise. Left ventricular relaxation rate was measured by calculation of a time constant of left ventricular pressure decay (T) derived from an exponential curve fit to the digitized tip-micromanometer left ventricular pressure signal. In the transplant recipients, exercise abbreviated T from 43 +/- 6 to 40 +/- 8 msec (p less than 0.01) and caused a rise of left ventricular minimum diastolic pressure (LVMDP) from 5 +/- 2 to 9 +/- 6 mm Hg (p less than 0.001). In normal control subjects, exercise induced a 2.5 times larger abbreviation of T (from 42 +/- 7 to 34 +/- 6 msec; p less than 0.001) and a small drop in LVMDP from 5 +/- 2 to 4 +/- 3 mm Hg (p less than 0.05). In the transplant recipients, the change in T (delta T) from rest to exercise was variable ranging from an abbreviation, as observed in normal controls, to a prolongation and was significantly correlated with the change in RR interval (delta RR) and the change in left ventricular end-diastolic pressure (delta LVEDP) (delta T = 0.068 delta RR + 0.58 delta LVEDP-2.2; r = 0.76; p less than 0.001). In a first subset of transplant recipients (n = 8), dobutamine infusion resulted in a heart rate equal to the heart rate at peak exercise, a left ventricular end-diastolic pressure (8 +/- 7 mm Hg) lower than at peak exercise (22 +/- 6 mm Hg; p less than 0.05) and a T value (32 +/- 9 msec), which was shorter than both resting value (44 +/- 5 msec; p less than 0.005) and value observed at peak exercise (40 +/- 8 msec; p less than 0.01). In a second subset of transplant recipients (n = 9), nitroprusside infusion and postextrasystolic potentiation resulted in a significant prolongation of T from 41 +/- 7 to 56 +/- 10 msec (p less than 0.05) and a characteristic negative dP/dt upstroke pattern with downward convexity as previously observed in left ventricular hypertrophy. CONCLUSIONS: Exercise after cardiac transplantation resulted in a smaller acceleration of left ventricular relaxation than in a normal control group exercised to the same heart rate...

Adult↗

PubMed2006

Serum levels of cartilage oligomeric matrix protein (COMP) increase temporarily after physical exercise in patients with knee osteoarthritis.

BACKGROUND: COMP (Cartilage oligomeric matrix protein) is a matrix protein, which is currently studied as a potential serum marker for cartilage processes in osteoarthritis (OA). The influence of physical exercise on serum COMP is not fully elucidated. The objective of the present study was to monitor serum levels of COMP during a randomised controlled trial of physical exercise vs. standardised rest in individuals with symptomatic and radiographic knee OA. METHODS: Blood samples were collected from 58 individuals at predefined time points before and after exercise or rest, one training group and one control group. The physical exercise consisted of a one-hour supervised session twice a week and daily home exercises. In a second supplementary study 7 individuals were subjected to the same exercise program and sampling of blood was performed at fixed intervals before, immediately after, 30 and 60 minutes after the exercise session and then with 60 minutes interval for another five hours after exercise to monitor the short-term changes of serum COMP. COMP was quantified with a sandwich-ELISA (AnaMar Medical, Lund, Sweden). RESULTS: Before exercise or rest no significant differences in COMP levels were seen between the groups. After 60 minutes exercise serum COMP levels increased (p < 0.001). After 60 minutes of rest the serum levels decreased (p = 0.003). Median serum COMP values in samples obtained prior to exercise or rest at baseline and after 24 weeks did not change between start and end of the study. In the second study serum COMP was increased immediately after exercise (p = 0.018) and had decreased to baseline levels after 30 minutes. CONCLUSION: Serum COMP levels increased during exercise in individuals with knee OA, whereas levels decreased during rest. The increased serum COMP levels were normalized 30 minutes after exercise session, therefore we suggest that samples of blood for analysis of serum COMP should be drawn after at least 30 minutes rest in a seated position. No increase was seen after a six-week exercise program indicating that any effect of individualized supervised exercise on cartilage turnover is transient.

Adult↗

PubMed2003

Regional specificity of exercise and calcium during skeletal growth in girls: a randomized controlled trial.

Combining exercise with calcium supplementation may produce additive or multiplicative effects at loaded sites; thus, we conducted a single blind, prospective, randomized controlled study in pre- and early-pubertal girls to test the following hypotheses. (1) At the loaded sites, exercise and calcium will produce greater benefits than exercise or calcium alone. (2) At non-loaded sites, exercise will have no benefit, whereas calcium with or without exercise will increase bone mass over that in exercise alone or no intervention. Sixty-six girls aged 8.8 +/- 0.1 years were randomly assigned to one of four study groups: moderate-impact exercise with or without calcium or low-impact exercise with or without calcium. All participants exercised for 20 minutes, three times a week and received Ca-fortified (434 +/- 19 mg/day) or non-fortified foods for 8.5 months. Analysis of covariance (ANCOVA) was used to determine interaction and main effects for exercise and calcium on bone mass after adjusting for baseline bone mineral content and growth in limb lengths. An exercise-calcium interaction was detected at the femur (7.1%, p < 0.05). In contrast, there was no exercise-calcium interaction detected at the tibia-fibula; however, there was a main effect of exercise: bone mineral content increased 3% more in the exercise than non-exercise groups (p < 0.05). Bone mineral content increased 2-4% more in the calcium-supplemented groups than the non-supplemented groups at the humerus (12.0% vs. 9.8%, respectively, p < 0.09) and radius-ulna (12.6% vs. 8.6%, respectively, p < 0.01). In conclusion, greater gains in bone mass at loaded sites may be achieved when short bouts of moderate exercise are combined with increased dietary calcium, the former conferring region-specific effects and the latter producing generalized effects.

Biomechanical Phenomena↗

PubMed2004

Effects of liquid carbohydrate ingestion on markers of anabolism following high-intensity resistance exercise.

We examined the effects of liquid carbohydrate (CHO) supplementation on markers of anabolism following high-intensity resistance exercise. Nine resistance-trained men consumed either CHO or placebo (PLC) 10 minutes before and immediately following 2 resistance exercise sessions. Cortisol (CORT), insulin (INS), ammonia (AMM), and glucose (GLU) were measured before, immediately after, and 1.5 and 4 hours after exercise. Urinary nitrogen (NH(+3)) was measured 24 hours before and after exercise. There was a significant difference in INS levels immediately after exercise and 1.5 hours after exercise. No significant differences were observed for CORT, AMM, GLU, or NH(+3)between treatments. Significant within-group differences were found for the PLC group: CORT before compared with immediately after exercise; INS before compared with immediately after exercise and before compared with 1.5 hours after exercise; and AMM before compared with immediately after exercise and before compared with 1.5 hours after exercise. Significant within-group differences were found for the CHO group: CORT immediately after compared with 1.5 hours after exercise and immediately after compared with 4 hours after exercise; INS before compared with 1.5 hours after exercise; and AMM before compared with immediately after exercise. Liquid CHO ingestion leads to a more favorable anabolic environment immediately following a resistance exercise bout; however, our indirect measures of protein degradation were not altered by CHO ingestion.

Adult↗

PubMed2002

Comparison of cardiovascular responses to isometric (static) and isotonic (dynamic) exercise tests in chronic atrial fibrillation.

The aim of the present study was to evaluate the tolerance to various exercises by determining the cardiovascular response to static and dynamic exercises in patients with nonvalvular atrial fibrillation. Fifty patients (mean age: 63.6 +/- 10.3 years; male: 25, female: 25) with chronic (more than one year) nonvalvular atrial fibrillation were included in the study. All patients underwent exercise tests, adjusted appropriately according to their symptoms, as dynamic exercise on a Marquette Case 15 device according to a modified Bruce protocol. Heart rate, and systolic and diastolic arterial pressures were measured at rest and at all stages of the exercise; and the heart rate-pressure products were evaluated. A handgrip test was also conducted as static exercise. The measurements were made before, at the 1st, 2nd and 3rd minutes, and in the recovery periods of the exercise. The percent values of the changes of the 1st, 2nd and 3rd minute measurements in relation to the initial values for both exercises were compared. In addition, the maximal responses to the exercise tests and the post exercise values were also compared. For statistical evaluations, the paired Student-t test was used. Heart rate and pressure-heart rate product values obtained at 1, 2, and 3 minutes during the treadmill exercise test were significantly high compared to the handgrip values (P < 0.0001). The arterial systolic and diastolic pressure values in the 1st minute were also significantly higher during the handgrip test (P = 0.0100 and P = 0.0320, respectively). The values of diastolic arterial pressure at the 2nd minute during the handgrip test, and systolic arterial pressure at the 3rd minute during the treadmill test were found to be statistically significant (P = 0.0240, P = 0.0340, respectively). The mean exercise time and MET value during the treadmill exercise test were 7.18 +/- 2.65 minutes and 5.32 +/- 1.38 mL.kg(-1) x dk(-1). respectively. During the recovery period, the 5th minute, heart rate and pressure-heart rate product values were significantly high after the treadmill test (P < 0.0001). In this study, we revealed that the heart rate response to static exercise was lower and the patients tolerated the static exercise better. Therefore, we decided that the short duration of static exercise is not harmful for the noncomplicated chronic atrial fibrillation cases.

Aged↗

PubMed1992

Muscle metabolism during repeated exercise studied by 31P-MRS.

We studied 31P-nuclear magnetic resonance spectroscopy (31P-MRS) for repeated non-invasive measurement of changes in the muscle metabolites, i.e., creatine phosphate (PCr) and inorganic phosphate (Pi), and changes in intramuscular pH, during repeated exercise and intervening rest periods. Six healthy male subjects performed 2 min of femoral flexion exercise at 20 kgm/min in a 2.1 Tesla superconducting magnet with a 67 cm bore. This exercise was repeated 4 times with 2-min rest periods between bouts. During this time 31P-MRS data was collected with 32 scans per spectrum, requiring 12.8 sec. During exercise, the PCr decreased to 30.3 +/- 7.0% (mean +/- SD) of the pre-exercise level, and it did not completely recover during the rest period (79.0 +/- 1.3% of the pre-exercise level). Thereafter, when the exercise was repeated, the lowest PCr value during exercise decreased gradually (2nd bout, 22.1 +/- 3.9%; 3rd bout, 16.7 +/- 3.2%, and 4th bout 14.9 +/- 3.5%). The Pi increased by 705-740% during exercise and there were no significant differences in maximum Pi among the 4 bouts. During the rest period after the first bout, Pi fell to about 10% below the pre-exercise level in four of the six subjects. With repeated exercise, this undershoot was less common. The Pi/PCr ratio during exercise increased linearly over time. Furthermore, the maximum Pi/PCr ratio during exercise increased significantly with repeated exercises. We conclude that as exercise is repeated PCr gradually decreases, but there is no cumulative increase in Pi. Thus, the Pi/PCr ratio, an indicator of free ADP, increased with repeated exercise.

Adult↗