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Exercise-induced changes in pulmonary function of healthy, elite long-distance runners in cold air and pollen season exercise challenge tests.

Exercise-induced changes in postexercise pulmonary function have not been studied in healthy elite athletes in normal training conditions. Twelve healthy elite runners volunteered. They showed normal resting spirometry and bronchial responsiveness to histamine, and were non-atopic. They performed free running exercise challenge tests (ECT) at subzero temperature and immediately after highest birch pollen season. The mean maximal postexercise changes in FEV(1), PEF, FVC, and FEV(1)/FVC did not differ between the cold air and pollen season ECTs. Compared with pre-exercise values, FEV(1)increased significantly at 10 min (p = 0.028) and 20 min (p = 0.033) postexercise in the cold air ECT, as well as at 10 min (p = 0.024) and 20 min (p = 0.010) postexercise in the pollen season ECT. The mean (SEM) maximal postexercise change in FEV(1) was mostly small + 2.6 (0.6)% in the winter and + 2.7 (0.9)% in the pollen season. In contrast, significant decreases in PEF, compared with baseline, were found at 10 min (p = 0.071) and 20 min (p = 0.0029) postexercise in the cold air ECT, as well as at 10 min (p = 0.060) and 20 min (p = 0.010) postexercise in the pollen season ECT (p = 0.0076). The mean (SEM) maximal postexercise fall in PEF was 5.9 (1.0)% in the winter and 6.0 (1.8)% in the pollen season. Heavy exercise challenge tests in extreme conditions increased FEV(1) post-exercise, while PEF decreased as compared with pre-exercise values. Thus, even small postexercise falls in FEV(1) may be considered as deviate exercise responses in elite athletes.

Adult↗

Influence of exercise intensity and duration on post-exercise pulmonary diffusion capacity.

Pulmonary diffusion capacity has been observed to be reduced by approximately 14% 2h after 4-6 min of maximal exercise. The purpose of this study was to determine if the decrease in pulmonary diffusion capacity also occurs when the duration of exercise intensity is shorter or when the exercise intensity is lower. We measured pulmonary diffusion capacity using the single breath method in 12 competitive rowers 22 (16-31) years old, 70 (56-100) kg body weight, and 180 (171-193) cm body height under two conditions: (1) 2h after 6 min of rowing at both 61% (58%-68%) and 76% (73%-78%) of maximal oxygen uptake; (2) 2h after 1, 2, or 3 min of all-out rowing. Values are presented as medians with ranges. Pulmonary diffusion capacity was reduced by 6% (2%-17%) after 6 min of rowing at 61% and by 10% (-7%-21%) after 6 min of rowing at 76% of maximal oxygen uptake (p < 0.03). Pulmonary diffusion capacity was reduced by 7% (3%-19%), 8% (2%-17%) and 7% (1%-16%) after 1, 2, and 3 min of all-out rowing (p < 0.01). We conclude that submaximal exercise at 61% of maximal oxygen uptake will affect pulmonary diffusion capacity following exercise as will shorter duration of maximal exercise. Although the mechanism for this fall in pulmonary diffusion capacity is unclear, the fact that it occurs after even mild exercise makes a significant change in pulmonary capillary membrane integrity or subclinical pulmonary edema unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Effects of exercise load and breathing frequency on heart rate and blood pressure variability during dynamic exercise.

It is known that heart rate (HR) variability decreases with dynamic exercise, but there are only few studies on blood pressure (BP) variability with exercise loads and the effect of breathing pattern has never been investigated. Thus, we studied HR and systolic blood pressure (SBP) signals by spectral analysis (FFT), in 9 healthy subjects, at different breathing frequencies (0.15, 0.2, 0.3, 0.4, 0.5, 0.6 Hz), at rest and during 3 exercise loads (25, 50 and 75% VO2max). BP was measured with a non-invasive device (Finapres) and continuously recorded. The power spectrum of R-R period significantly decreased with exercise loads in the low frequency band (LF: 0.04-0.128 Hz) and in the high frequency band (HF: 0.128-0.65 Hz), but with breathing frequency only in the HF part of the spectrum. The power spectrum of SBP significantly increased with exercise loads in LF and HF bands, and decreased in HF band with increasing breathing frequency. R-R and SBP HF peaks were centered on breathing frequency peaks. Therefore, spectral analysis of HR and SBP confirm the withdrawal of vagal control during exercise, while mechanical effect of respiration on SBP persists. LF/HF ratio of R-R spectral components decreased with increasing load, whereas cardiovascular sympathetic activity is known to rise, suggesting that this ratio is not a good indicator of cardiovascular autonomic modulation during exercise.

Adolescent↗

Continuing regular exercise during pregnancy: effect of exercise volume on fetoplacental growth.

OBJECTIVE: The purpose of this study was to test the null hypothesis that the volume of exercise at different times during pregnancy has no effect on fetoplacental growth. STUDY DESIGN: Seventy-five women who exercised regularly were evaluated before pregnancy and randomly assigned at 8 weeks' gestation to one of 3 exercise regimens for the remainder of pregnancy. Primary outcome variables included placental growth rate, birth weight, and placental volume at term. RESULTS: The offspring of the women who were randomly assigned to a high volume of exercise in mid and late pregnancy were significantly lighter (3.39 kg vs 3.81 kg) and thinner (8.3% fat vs 12.1% fat) than those offspring born of women who were randomly assigned to reduce their exercise volume after the 20th week. Maternal weight gain, fresh placental volumes, and histomorphometric indices of placental function were greater in the high-low group. CONCLUSION: These data indicate that a high volume of moderate-intensity, weight-bearing exercise in mid and late pregnancy symmetrically reduces fetoplacental growth, whereas a reduction in exercise volume enhances fetoplacental growth with a proportionally greater increase in fat mass than in lean body mass.

Adult↗

Ascorbic acid supplementation does not attenuate post-exercise muscle soreness following muscle-damaging exercise but may delay the recovery process.

Exercise involving lengthening muscle actions, such as downhill running, results in delayed onset muscle soreness (DOMS), which may be attributable to reactive oxygen species (ROS). Although exercise causes oxidative stress, any link between ROS and DOMS remains speculative. There is emerging evidence to suggest that ROS play an important physiological role, assisting in the recovery process and protecting the cell from future damage; however, this has not been fully established. Despite this uncertainty as to the precise role of ROS, attempts to prevent post-exercise ROS production through antioxidant intervention are still common. The study investigated the effects of ascorbic acid supplementation on ROS production and DOMS following downhill running. Subjects were assigned to two groups. The ascorbic acid group (group AA) received 1 g ascorbic acid 2 h pre-, and for 14 d post-downhill running, whilst the placebo group (Pl group) received a placebo. Blood samples were drawn pre-supplement, pre- and post-exercise, and then 1, 2, 3, 4, 7 and 14 d post-exercise for analysis of ascorbate, malonaldehyde and total glutathione. DOMS was assessed using a visual analogue scale and pressure algometry. Muscle function was assessed using isokinetic dynamometry. Plasma ascorbate was elevated throughout in group AA compared with the Pl group. Downhill running resulted in DOMS in both groups. Muscle function was impaired post-exercise in both groups, although a delayed recovery was noted in group AA. Malonaldehyde increased 4 d post-exercise in the Pl group only. Ascorbic acid supplementation attenuates ROS production following downhill running, without affecting DOMS. Furthermore, ascorbic acid supplementation may inhibit the recovery of muscle function.

Adult↗

Respiratory gas exchange during treadmill exercise testing: reproducibility and comparison of different exercise protocols.

Ten subjects performed 4 maximal exercise tests to evaluate reproducibility and effects of treadmill inclination on submaximal and maximal oxygen consumption. They performed a standard Bruce protocol twice, and 1 protocol with progressive speed increase with constant, or without, inclination. At maximal exercise there was no significant difference between the protocols in oxygen consumption, respiratory gas exchange ratio, minute ventilation, plasma lactate, serum potassium or heart rate. Exercise time and treadmill distance were shorter than Bruce protocol with inclination, and considerably prolonged without. Reproducibility for Bruce protocol was good for group comparison of oxygen consumption throughout exercise. The individual variations for oxygen consumption were small at maximal exercise, but were considerable at rest and at the lowest exercise steps, this was slightly improved by analysing longer sampling time. Thus, measurement of oxygen consumption is reliable for group analysis, but interpretation must be careful in individuals unless maximal exercise is obtained. Treadmill inclination may be adjusted according to individual preferences.

Adolescent↗

Reasons for not exercising and exercise intentions: a study of middle-aged sedentary adults.

The aims of this study were to assess why people do not participate in exercise and physical activity, and what might lead them to become active. More specifically, we focused on the hindrances to entering the phase of transition from a sedentary to a more active lifestyle by analysing the reasons 265 middle-aged Belgian adults gave for their inactivity. Their justifications were examined in relation to the conditions which they say would be needed for them to become more involved in regular physical activity. Factor analysis revealed that the reasons for inactivity referred to the adults' self-concept, to cognitive cost-benefit based processes and to negative emotions associated with exercise. The conditions reported to be necessary to begin exercising referred to a perceived decrease in health and to the appropriateness of the exercise offered. Discriminant analysis showed that 'never-exercisers' differed from 'ex-exercisers', and that within the subgroup of 'ex-exercisers' the long-term drop-outs differed from the recent drop-outs. Cluster analysis revealed three types of sedentary adults: the unconcerned, the opposed and the approachable.

Adult↗

Comparison of the effects of two doses of bisoprolol on exercise tolerance in exercise-induced stable angina pectoris.

Recently, bisoprolol has been investigated regarding its effects on exercise tolerance and the duration of action in patients with coronary heart disease (CHD) following single oral administration. It appears, however, that the extent of effects of 5 mg bisoprolol is not fully established yet. Therefore, the effects of 5 and 10 mg bisoprolol and the duration of action were assessed in 12 patients (10 male, 2 female; mean age 60.2 years) with stable angina pectoris due to CHD after repeated administration. Patients were given 5 or 10 mg bisoprolol once daily for 2 weeks according to a double-blind, randomized cross-over design. At entry one exercise tolerance test (ETT) served as baseline measurement and following each treatment period ETTs were performed before (24-hour value) and 3 hours after tablet intake. Exercise capacity (in W X min) was calculated until the onset of angina, 0.1 mV ST-segment depression and at peak exercise. Compared to baseline all workload values during active therapy were significantly improved (P less than or equal to 0.05) except for the workload till onset of angina with bisoprolol 5 mg at 24 hours. The effects at 3 hours were significantly stronger than those after 24 hours for both dosages. Significantly stronger effects were observed 3 hours as well as 24 hours after intake during treatment with 10 mg compared to 5 mg: at peak exercise on heart rate (P less than or equal to 0.05) and exercise capacity (P less than or equal to 0.01), at identical workload on heart rate (P less than or equal to 0.01) and rate-pressure product (P less than or equal to 0.01). It was found that bisoprolol 5 mg once daily leads to therapeutic effects with a clearly maintained duration of action over 24 hours, but further increase of peak exercise capacity may be achieved with 10 mg.

Administration, Oral↗

A single bout of concentric resistance exercise increases basal metabolic rate 48 hours after exercise in healthy 59-77-year-old men.

BACKGROUND: It has been shown that basal metabolic rate (BMR) decreases with age. The extent to which some of the decrease can be reversed by exercise in older men and women is unclear. Resistance exercise has been shown to significantly increase muscle mass in older individuals, and because muscle is a highly active metabolic tissue there is potential to increase BMR as a secondary outcome to the training adaptation. METHODS: Twelve healthy men aged 59-77 years performed single-leg knee extension exercise (right and left leg) and bench press lifts (16 sets, 10 reps/set with timed recovery between sets) at 75% of the individual's 3RM. Subjects only performed the concentric phase of the lift. BMR was measured on two separate occasions, once after a nonexercise control period and again 48 hrs after a bout of resistance exercise. RESULTS: BMR was significantly increased (p < .006) 48 hrs after exercise (EX) compared to control (CON) (284.0 +/- 34.0 vs 274.9 +/- 34.0 kJ/hr, respectively). Calculated over a 24-hour period, the energy expenditure corresponded to 1570 +/- 193 and 1627 +/- 193 kcal/24 hr (p < .0002) for the CON and EX measures, respectively. VO2 (L/min) was higher (p < .0002) 48 hrs after the EX bout compared to 48 hrs post-CON (0.232 +/- 0.03 vs 0.225 +/- 0.03 L/min, respectively). CONCLUSION: We conclude that in healthy 59-77-year-old men, an acute bout of resistance exercise causes a sustained increase in BMR that persists for up to 48 hours after exercise.

Aged↗

Exercise and depressive symptoms: a comparison of aerobic and resistance exercise effects on emotional and physical function in older persons with high and low depressive symptomatology.

This study examines and compares the effect of aerobic and resistance exercise on emotional and physical function among older persons with initially high or low depressive symptomatology. Data are from the Fitness, Arthritis and Seniors Trial, a trial among 439 persons 60 years or older with knee osteoarthritis randomized to health education (control), resistance exercise, or aerobic exercise groups. Depressive symptoms (assessed by the Center for Epidemiologic Studies--Depression scale) and physical function (disability, walking speed, and pain) were assessed at baseline and after 3, 9, and 18 months. Compared with results for the control group, aerobic exercise significantly lowered depressive symptoms over time. No such effect was observed for resistance exercise. The reduction in depressive symptoms with aerobic exercise was found both among the 98 participants with initially high depressive symptomatology and among the 340 participants with initially low depressive symptomatology and was the strongest for the most compliant persons. Aerobic and resistance exercise significantly reduced disability and pain and increased walking speed both, and to an equal extent, in persons with high depressive symptomatology and persons with low depressive symptomatology.

Activities of Daily Living↗

A comparison of isometric exercise, cold pressor stimulation and dynamic exercise in patients with coronary heart disease.

Isometric exercise and cold pressor stimulation have been proposed as alternatives to dynamic exercise in the evaluation of patients with coronary heart disease. We evaluated all three, by gated radionuclide ventriculography, in 13 male controls and 44 male patients with coronary heart disease. In controls, mean left ventricular ejection fraction did not change during isometric exercise or cold pressor stimulation (64 +/- 2 to 63 +/- 2 and 63 +/- 3) but fell significantly in patients (56 +/- 1 to 53 +/- 1 and 53 +/- 1, both P less than 0.001). During dynamic exercise, mean left ventricular ejection fraction rose in controls (64 +/- 2 to 84 +/- 2, P less than 0.001) but did not change in patients (56 +/- 1 to 56 +/- 2). There was considerable overlap between the groups in the left ventricular ejection fraction response to isometric exercise and cold pressor stimulation; only dynamic exercise discriminated between them. Isometric exercise and cold pressor stimulation are of little value in the diagnosis of coronary heart disease by radionuclide ventriculography.

Adult↗

Low back exercises: evidence for improving exercise regimens.

Despite the wide variety of exercises that are prescribed for the low back, the scientific foundation to justify their choice is not as complete as one may think, or expect. Thus, the clinician must often call upon "clinical opinion" when selecting exercise. Given that low back tissues may need stressing to enhance their health but too much loading can be detrimental, choosing the optimal exercise requires judgment based on clinical experience and scientific evidence. To assist in developing better exercise programs, this review documents some recent biomechanical evidence from my laboratory and from laboratories of other researchers that has been reported in various publications in an attempt to update clinicians on issues of low back exercise. Among the issues examined are mechanisms of injury; the relative importance of "strength" (ie, maximum force a muscle can produce during a single exertion to create joint torque), "flexibility," and "endurance"; and training to enhance stability. Finally, some specific exercises are described that have been shown to challenge muscle and enhance performance but that are performed in such a way as to minimize loading of the spine to reduce the risk of injury exacerbation. These exercises form a basic program for rehabilitation and maintenance of low back health.

Biomechanical Phenomena↗

Are exercise-induced genes induced by exercise?

Numerous human in vivo studies on skeletal muscle gene expression have investigated the effects of given interventions. These have been founded on the assumption that presampling can be regarded as a representative control for postintervention sampling. However, many genes are responsive to the metabolic status, which varies during the day, so that observed differences in gene expression between the pre- and post-sample may therefore be a result of the daily variations rather than an intervention. Furthermore, the sampling itself can cause a local stress response, which may also influence the expression of some genes in later samples from the same localized area. To test this, we performed a short-term human endurance exercise study in which muscle biopsies were obtained from healthy untrained individuals (n=14) before and in the hours after exercise to measure the expression of mRNA for previously reported exercise-related genes (e.g., PPARgamma coactivator-1alpha (PGC-1alpha), pyruvate dehydrogenase kinase 4 (PDK4), MyoD, p21, (heat shock protein 72 (HSP72), lipoprotein lipase (LPL), citrate synthase (CS), and glucose transporter 4 (GLUT4)). To test for changes unrelated to exercise, one half of the subjects did not exercise. As suspected, several presumed exercise-induced genes were induced even without the exercise. Our data demonstrate that presampling is not always a representative control for postintervention sampling, illustrating that use of presampling can cause erroneous interpretations of the underlying induction signals.

Adult↗

Heart rate variability and the exercise pressor reflex during dynamic handgrip exercise and postexercise arterial occlusion.

BACKGROUND: The exercise pressor reflex is thought to be an important cardiovascular control mechanism that may be compromised in disease states such as congestive heart failure and other metabolic syndromes. The purpose was to describe the exercise pressor reflex by observing heart rate variability and blood pressure responses to handgrip-exercise and postexercise arterial occlusion. METHODS: Continuous electrocardiography, arterial blood pressure, and pneumotachogram data were collected on 38 participants (age, 20 +/- 1 year) during spontaneous breathing, venous-occluded exercise (60% maximal voluntary contraction, 0.5 Hz) and immediate postexercise arterial occlusion. Data were analyzed for mean R-R interval, standard deviation of R-R intervals (SDNN), normalized low (0-0.15 Hz) frequency power (LFnu), mean arterial pressure (MAP), and respiratory rate. RESULTS: During exercise, increases in respiratory rate (+4.55 +/- 6.48 breaths/min), LFnu (+9.39 +/- 16.83%), and MAP (+25.40 +/- 17.55 mm Hg) were observed. Mean R-R interval (-230.73 +/- 125.79 msec) and SDNN (-38.54 +/- 36.02 msec) decreased (P < 0.05). Respiratory rate (+0.12 +/- 4.61 breaths/min), SDNN (-17.89 +/- 64.41 msec), and LFnu (9.89 +/- 21.01%) recovered during forearm arterial occlusion (P < 0.05). However, Mean R-R interval and MAP remained elevated above spontaneous breathing (P < 0.05). CONCLUSIONS: The sustained elevation in MAP during postexercise arterial occlusion suggests metaboreceptor-mediated heightened sympathetic activity. The increase in LFnu during exercise and its subsequent recovery during postexercise occlusion is consistent with dynamic exercise-induced parasympathetic withdrawal but a strong vagal activation upon cessation of dynamic activity despite persistent sympathetic activity originating from afferent input from the occluded forearm.

Adult↗

Exercise training decreases the growth hormone (GH) response to acute constant-load exercise.

To assess the influence of exercise training on the growth hormone (GH) response to acute exercise, six untrained males completed a 20-min, high-intensity, constant-load exercise test prior to and after 3 and 6 wk of training (the absolute power output (PO) during each test remained constant x PO = 182.5 +/- 29.5 W). Training increased (pre- vs post-training) oxygen uptake (VO2) at lactate threshold (1.57 +/- 0.33 L.min-1 vs 1.97 +/- 0.24 L.min-1 P < or = 0.05). VO2 at 2.5 mM blood lactate concentration ([HLa]) (1.83 +/- 0.38 L.min-1 vs 2.33 +/- 0.38 L.min-1, P < or = 0.05), and VO2peak (3.15 +/- 0.54 L.min-1 vs 3.41 +/- 0.47 L.min-1, P < or = 0.05). Power output at the lactate threshold (PO-LT) increased with training from 103 +/- 28 to 132 +/- 23W (P < or = 0.05). Integrated GH concentration (20 min exercise + 45 min recovery) (microgram.L-1 x min) after 3 wk (138 +/- 106) and 6 wk (130 +/- 145) were significantly lower (P < or = 0.05) than pre-training (238 +/- 145). Plasma epinephrine and norepinephrine responses to training were similar to the GH response (EPI-pre-training = 2447 +/- 1110; week 3 = 1046 +/- 144; week 6 = 955 +/- 322 pmol.L-1; P < or = 0.05; NE pre-training = 23.0 +/- 5.2; week 3 = 13.4 +/- 4.8; week 6 = 12.1 +/- 6.8 nmol.L-1; P < or = 0.05). These data indicate that the GH and catecholamine response to a constant-load exercise stimulus are reduced within the first 3 wk of exercise training and support the hypothesis that a critical threshold of exercise intensity must be reached to stimulate GH release.

Adult↗

Does it matter which exercise? A randomized control trial of exercise for low back pain.

STUDY DESIGN: Multicentered randomized controlled trial. OBJECTIVES: To determine if previously validated low back pain (LBP) subgroups respond differently to contrasting exercise prescriptions. SUMMARY OF BACKGROUND DATA: The role of "patient-specific" exercises in managing LBP is controversial. METHODS: A total of 312 acute, subacute, and chronic patients, including LBP-only and sciatica, underwent a standardized mechanical assessment classifying them by their pain response, specifically eliciting either a "directional preference" (DP) (i.e., an immediate, lasting improvement in pain from performing either repeated lumbar flexion, extension, or sideglide/rotation tests), or no DP. Only DP subjects were randomized to: 1) directional exercises "matching" their preferred direction (DP), 2) exercises directionally "opposite" their DP, or 3) "nondirectional" exercises. Outcome measures included pain intensity, location, disability, medication use, degree of recovery, depression, and work interference. RESULTS: A DP was elicited in 74% (230) of subjects. One third of both the opposite and non-directionally treated subjects withdrew within 2 weeks because of no improvement or worsening (no matched subject withdrew). Significantly greater improvements occurred in matched subjects compared with both other treatment groups in every outcome (P values <0.001), including a threefold decrease in medication use. CONCLUSIONS: Consistent with prior evidence, a standardized mechanical assessment identified a large subgroup of LBP patients with a DP. Regardless of subjects' direction of preference, the response to contrasting exercise prescriptions was significantly different: exercises matching subjects' DP significantly and rapidly decreased pain and medication use and improved in all other outcomes. If repeatable, such subgroup validation has important implications for LBP management.

Exercise Therapy↗

Special feature for the Olympics: effects of exercise on the immune system: exercise and cytokines.

Strenuous exercise induces increased levels in a number of pro-inflammatory and anti-inflammatory cytokines, naturally occurring cytokine inhibitors and chemokines. Thus, increased plasma levels of TNF-alpha, IL-1, IL-6, IL-1 receptor antagonist, TNF receptors, IL-10, IL-8 and macrophage inflammatory protein-1 are found after strenuous exercise. The concentration of IL-6 increases up to 100-fold after a marathon race. The increase in IL-6 is tightly related to the duration of the exercise and there appears to be a logarithmic relationship. Furthermore, the increase in IL-6 is related to the intensity of exercise. Given the facts that IL-6, more than any other cytokine, is produced in large amounts in response to exercise, that IL-6 is produced locally in the skeletal muscle in response to exercise and that IL-6 is known to have growth factor abilities, it is likely that IL-6 plays a beneficial role and may be involved in mediating exercise-related metabolic changes.

Acute-Phase Reaction↗

Vigorous exercise and birth outcomes in a sample of recreational exercisers: a prospective study across pregnancy.

OBJECTIVE: This study examined the question of whether vigorous exercise undertaken by recreational exercisers across pregnancy, defined in two ways, were associated with reduced infant birthweight and gestational age at birth. METHODS: A prospective approach was implemented. A total of 148 pregnant women participated. Average intensity duration and frequency of vigorous exercise reported were examined and compared with two existing definitions of vigorous exercise. Participants completed questionnaires (including retrospective reports on 3 months prepregnancy) and an exercise diary at 16-23 weeks pregnancy, 24-31 weeks pregnancy and 32-38 weeks pregnancy, and at 7 to 14 days post-partum a birth outcomes questionnaire was completed. RESULTS: There were no significant differences between exercise groups for birthweight and gestational age at birth. CONCLUSIONS: There was no evidence that the intensity duration and frequency of vigorous exercise were associated with significant reductions in mean birth outcomes for the infants of women who participated in the study. Replication in a large, more diverse sample is recommended.

Adult↗