Impaired myocardial relaxation with exercise determines peak aerobic exercise capacity in heart failure with preserved ejection fraction

Background Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome characterized by impaired exercise capacity due to shortness of breath and/or fatigue. Assessment of diastolic dysfunction at rest and with exercise may provide insight into the pathophysiology of exercise intolerance in HFpEF. Aims To measure echocardio-Doppler-derived parameters of diastolic function as they relate to various indices of aerobic exercise capacity in HFpEF. Methods We selected 16 subjects with clinically stable HFpEF, no evidence of volume overload, but impaired functional capacity by cardiopulmonary exercise testing [peak oxygen consumption (VO2)]. We measured the transmitral E and A flow velocities, E/A ratio, and E deceleration time (DT) and tissue Doppler E′ velocity. We also indexed the E′ to the DT, as additional measure of impaired relaxation (E′DT), and calculated the diastolic functional reserve index (DFRI), as the product of E′ at rest and change in E′ with exercise. Results E′ velocity, at rest and peak exercise, as well as the DFRI positively correlated with peak VO2, whereas DT, E′DT, and E/E′ with exercise inversely correlated with peak VO2. Of note, the E′DT at rest also significantly predicted E′ velocity at peak exercise (R = +0.81, P \u3c 0.001). Exercise E′ was the only independent predictor of peak VO2 at multivariable analysis (R = +0.67, P = 0.005). Conclusions The E′ velocity at peak exercise is a strong and independent predictor of aerobic exercise capacity as measured by peak VO2 in patients with HFpEF, providing the link between abnormal myocardial relaxation with exercise and impaired aerobic exercise capacity in HFpEF

Exercise training and losartan improve endothelial function in heart failure rats by different mechanisms

Objectives. To investigate the mechanisms of losartan- and exercise training-induced improvements on endothelial dysfunction in heart failure. Design. Sprague-Dawley rats subjected to left coronary artery ligation inducing myocardial infarction and heart failure were randomized to losartan treatment, high-intensity exercise training, or both. Results. Losartan, but not exercise training, reduced the heart failure-associated elevation in left ventricular end-diastolic pressure (26 ± 2 mmHg vs. 19 ± 1 mmHg after losartan). In contrast, both exercise training and losartan improved exercise capacity, by 40% and 20%, respectively; no additional effects were observed when exercise training and losartan were combined. Aortic segments were mounted on a force transducer to determine vasorelaxation. Heart failure impaired endothelium-dependent vasorelaxation, observed as a 1.9-fold reduced response to acetylcholine (EC50). Exercise and losartan improved acetylcholine-mediated vasorelaxation to the same extent, but by different mechanisms. Exercise training upregulated the nitric oxide pathway, whereas losartan upregulated a non-nitric oxide or -prostacyclin pathway; possibly involving the endothelium-dependent hyperpolarizing factor. Conclusions. Both losartan and exercise training reversed endothelial dysfunction in heart failure; exercise training via nitric oxide-dependent vasorelaxation, and losartan via an unknown mechanism that may involve endothelium-dependent hyperpolarizing factor. Thus, the combined treatment activated an additional nitric oxide- independent mechanism that contributed to reduce endothelial dysfunction

Can exercise limits prevent post-exertional malaise in chronic fatigue syndrome? An uncontrolled clinical trial.

<b>Objective</b>: It was hypothesized that the use of exercise limits prevents symptom increases and worsening of their health status following a walking exercise in people with Chronic Fatigue Syndrome (CFS). <b>Design</b>: An uncontrolled clinical trial (semi-experimental design). <b>Setting</b>: Outpatient clinic of a university department. <b>Subjects</b>: 24 patients with CFS. <b>Interventions</b>: Subjects undertook a walking test with the two concurrent exercise limits. Each subject walked at an <i>intensity</i> where the maximum heart rate was determined by heart rate corresponding to the respiratory exchange ratio =1.0 derived from a previous sub-maximal exercise test and for a duration calculated from how long each patient felt they were able to walk. <b>Main outcome measures</b>: The Short Form 36 Health Survey or SF-36, the CFS Symptom List, and the CFS-Activities and Participation Questionnaire were filled in prior to, immediately and 24 hours post-exercise. <b>Results</b>: The fatigue increase observed immediately post-exercise (p=0.006) returned to pre-exercise levels 24 hours post-exercise. The increase in pain observed immediately post-exercise was retained at 24 hours post-exercise (p=0.03). Fourteen of 24 subjects experienced a clinically meaningful change in bodily pain (change of SF-36 bodily pain score ³10). Six of 24 participants indicated that the exercise bout had slightly worsened their health status, and 2 of 24 had a clinically meaningful decrease in vitality (change of SF-36 vitality score ³20). There was no change in activity limitations/participation restrictions. <b>Conclusion</b>: It was shown that the use of exercise limits (limiting both the intensity and duration of exercise) prevents important health status changes following a walking exercise in people with CFS, but was unable to prevent short-term symptom increases

Appetite, energy intake and resting metabolic responses to 60 min treadmill running performed in a fasted versus a postprandial state.

This study investigated the effect of fasted and postprandial exercise on appetite, energy intake and resting metabolic responses. Twelve healthy males (mean±SD: age 23±3 years, body mass index 22.9±2.1 kg m(-2), maximum oxygen uptake 57.5±9.7 mL kg(-1) min(-1)) performed three 10 h experimental trials (control, fasted exercise and postprandial exercise) in a Latin Square design. Trials commenced at 8 am after an overnight fast. Sixty min of treadmill running at ∼70% of maximum oxygen uptake was performed at 0-1 h in the fasted exercise trial and 4-5 h in the postprandial exercise trial. A standardised breakfast was provided at 1.5 h and ad libitum buffet meals at 5.5 and 9.5 h. Appetite ratings and resting expired air samples were collected throughout each trial. Postprandial exercise suppressed appetite to a greater extent than fasted exercise. Ad libitum energy intake was not different between trials, resulting in a negative energy balance in exercise trials relative to control after accounting for differences in energy expenditure (control: 9774±2694 kJ; fasted exercise: 6481±2318 kJ; postprandial exercise: 6017±3050 kJ). These findings suggest that 60 min treadmill running induces a negative daily energy balance relative to a sedentary day but is no more effective when performed before or after breakfast

Effect of inspiratory pressure support on exercise performance in patients with chronic obstructive pulmonary disease

Title: Effect of inspiratory pressure support on exercise performance in patients with chronic obstructive pulmonary disease. Purpose: This study examined the effects of a non-invasive ventilator on submaximal and maximal exercise performance in patients with chronic obstructive pulmonary disease (COPD). Methods: Fourteen men (66.0 ± 7.4yr) and six women (59.0 ± 7.4yr) with a diagnosis of COPD, a forced expiratory volume! (FEVi) <40%, and the ability to tolerate 12 cmH20 of pressure on a non- invasive ventilator performed two maximal exercise tests on a cycle ergometer, with and without ventilatory assistance prior to exercise. Blood samples, respiratory metabolic measures, heart rate and rating of perceived exertion (RPE) were obtained throughout each exercise test. Results: Peak work rate (W), total exercise time, and respiratory rate were higher (p<0.05) when exercise was preceded by ventilatory support compared to no support. There was no difference in peak oxygen uptake (V02), carbon dioxide (VC02,), heart rate (HR), minute ventilation (VE), tidal volume (VT), blood lactate or RPE between the two experimental conditions. A total of 12 subjects completed at least 5 stages of the exercise protocol, and their physiological response during exercise with NIV and without NIV were compared. RPE was significantly lower during the first 3 min in the NIV condition than the no NIV condition. Circulating levels of blood lactate were lower (p<0.01) during stage 3 in the NIV than the than no NIV condition. There was no difference in RR, VT, HR, %HR, VE, V 0 2and %V02 between the two experimental conditions during sub maximal exercise. Conclusions: Application of non-invasive ventilatory support prior to exercise improves maximal exercise performance, but has no effect on cardio-metabolic response during submaximal exercise in patients with COPD

An Investigation of Exercise-Induced Hypoalgesia After Isometric and Cardiovascular Exercise

Exercise-induced hypoalgesia is a well-established phenomenon in the literature. The underlying mechanisms responsible for this augmentation of pain perception are not completely understood. The specific mode and intensity of exercise that creates hypoalgesia remains equivocal. Therefore, the purpose of this study was to identify if any differences existed in the exercise-induced hypoalgesia of isometric gripping exercise (IGE) and treadmill exercise (TE). A repeated measures design was used to determine the differences in pain threshold between acute exposure to IGE and TE. Twelve healthy male volunteers served as our subjects. Subjects were tested on three different days under three different conditions (rest, IGE, TE). The order of the trials was randomized and applied force (AF) was used as the dependent variable. Applied force pain threshold (AFPT) was determined by a handheld dolorimeter used to apply progressive force and pain to the skin and muscles of the wrist flexors before and after exercise. Exercise induced hypoalgesia was found in both exercise conditions by comparing resting PPT values (6.23 ± 2.04) to those measured immediately after IGE (7.24 ± 1.61; p = 0.0058) or TE (8.03 ± 2.03; p = 0.0001). However, TE produced a larger (22.04 %) hypoanalgesic effect in comparison to isometric exercise (14.14 %). Both TE and IGE may have potential as methods of increasing one’s pressure pain threshold. Further investigation into the specific causes of exercise-induced hypoalgesia is warranted

Effects of exercise-induced arterial hypoxemia on limb muscle fatigue and performance

1. Reductions in arterial O2 saturation (−5% to −10% SaO2 below rest) occur over time during sustained heavy-intensity exercise in a normoxic environment, caused primarily by the effects of acid pH and increased temperature on the position of the HbO2 dissociation curve. 2. We prevented the desaturation incurred during exercise at ∼90% √O2 MAX via increased fraction of inspired O2 (FiO2) (0.23 to 0.29) and showed that exercise time to exhaustion was increased. 3. We used supramaximal magnetic stimulation (1–100 Hz) of the femoral nerve to test for quadriceps fatigue. We used mildly hyperoxic inspirates (FiO2 0.23 to 0.29) to prevent O2 desaturation. We then compared the amount of quadriceps fatigue incurred following cycling exercise at SaO2 91% vs 98% with each trial carried out at identical work rates and for equal durations. 4. Preventing the normal exercise-induced O2 desaturation prevented about one-half the amount of exercise-induced quadriceps fatigue; plasma lactate and effort perception were also reduced. In a subset of less fit subjects who showed only minimal arterial hypoxaemia during sustained exercise (SaO2 ∼95%), breathing a mildly hypoxic inspirate (FiO2 0.17; SaO2 ∼88%) exacerbated the quadriceps fatigue. 5. We conclude that the normal exercise-induced O2 desaturation during heavy-intensity endurance exercise contributes significantly to exercise performance limitation in part because of its effect on locomotor muscle fatigue

Interaction of external, introjected, and identified regulation with intrinsic motivation in exercise: Relationships with exercise enjoyment

The present study examined the way in which the exercise-related motives of external regulation, introjected regulation, and identified regulation interacted with intrinsic motivation to relate to exercise enjoyment. The study was conducted to test the "additive relationship hypothesis" emanating from Vallerand and Fortier's (1998) theoretical position regarding the interplay between extrinsic and intrinsic motivation in exercise. Exercise participants (N = 516) responded to a self-report questionnaire assessing their reasons for exercise participation before the commencement of a single exercise class. One week later, and immediately prior to the corresponding class, participants reported on their levels of exercise enjoyment. Interactional analyses using linear regression showed a significant interaction between identified regulation and intrinsic motivation. Specifically, the coexistence of high levels of identified regulation with high levels of intrinsic motivation corresponded with higher scores on exercise enjoyment. External regulation and introjected regulation did not interact with intrinsic motivation, thus supporting the research hypotheses. Collectively, the present findings supported the validity of Vallerand and Fortier's theoretical propositions in the exercise domain and specifically the additive relationship hypothesis between identified regulation and intrinsic motivation with respect to exercise enjoyment

Interval Running Exercise Reduces Running TIME of 800 Meters Dash Without Causing Increased Level of Sgot – Sgpt in Male Students of the Faculty of Sports Sciences, Manado State University

The effort to gain best achievement in sports by means of exercise has twodilemmatic sides, both for the coaches and sport promoters. On one side, exercise shouldbe done intensely and maximally, but on the other side, it is a known fact that excessiveand maximal exercises can damage the body organs. The purposes of this study were toobserve the side effects of interval running exercise of 800 meters, to find out level offatigue by examining lactate acid produced by each model, and to assess the negativeeffects on organs as indicated by the level of SGOT-SGPT. The exercise model appliedin the study comprised interval running of 2 x 800 meters, 4 x 400 meters, 8 x 200meters, 16 x 100 meters and one standard of comparison exercise, which was runningexercise of 2 x 800 meters with passive rest. This study was true experimental usingrandomized pre-test-post-test control group design. Samples of this study were 27 malestudents of the Faculty of Sports Sciences, Manado State University, who were dividedinto five groups. Group 1 was with interval running exercise of 2 x 800 meters. Group 2was assigned to interval running exercise of 4 x 400 meters. Group 3 was with intervalrunning exercise of 8 x 200 meters. Group 4 was with interval running exercise of 16 x100 meters. Group 5 as comparison standard was with running exercise of 2 x 800 meterspassive rest. All the exercise models were carried out for six weeks, each with afrequency of three times a week. Results of the study showed that the five groupsdemonstrated reduction of running time of 800 meters dash (p&lt;0.05), lactate acidproduction differed in some of the groups (p&gt;0.05), levels of SGOT and SGPT of allgroups did not show significant increase (p&gt;0.05). From the above findings, it can beconcluded that all exercise models of interval running 2 x 800 meters, 4 x 400 meters, 8 x200 meters, 16 x 100 meters and 2 x 800 meters with passive rest lowered the runningtime of 800 meters dash and did not increase level of SGOT-SGPT