Bout Of Low-intensity Exercise Research Articles

Acute Statin Withdrawal Does not Interfere With the Improvements of a Session of Exercise in Postprandial Metabolism.

The risk for atherogenic plaque formation is high after ingestion of meals in individuals with high blood lipid levels (ie, dyslipidemia). Statins and exercise reduce the rise of blood triglyceride concentrations after a meal, but the effect of their combination is unclear. In a randomized crossover design, 11 individuals with dyslipidemia and metabolic syndrome treated with statins underwent a mixed-meal (970 ± 111 kcal, 24% fat, and 34% carbohydrate) tolerance test. Plasma lipid concentrations, fat oxidation, glucose, and glycerol kinetics were monitored immediately prior and during the meal test. Trials were conducted with participants under their habitual statin treatment and 96 hours after blinded statin withdrawal. Trials were duplicated after a prolonged bout of low-intensity exercise (75 minutes at 53 ± 4% maximal oxygen consumption) to study the interactions between exercise and statins. Statins reduced postprandial plasma triglycerides from 3.03 ± 0.85 to 2.52 ± 0.86 mmol·L-1 (17%; P = .015) and plasma glycerol concentrations (ie, surrogate of whole-body lipolysis) without reducing plasma free fatty acid concentration or fat oxidation. Prior exercise increased postprandial plasma glycerol levels (P = .029) and fat oxidation rates (P = .024). Exercise decreased postprandial plasma insulin levels (241 ± 116 vs 301 ± 172 ρmol·L-1; P = .026) but not enough to increase insulin sensitivity (P = .614). Neither statins nor exercise affected plasma glucose appearance rates from exogenous or endogenous sources. In dyslipidemic individuals, statins reduce blood triglyceride concentrations after a meal, but without limiting fat oxidation. Statins do not interfere with exercise lowering the postprandial insulin that likely promotes fat oxidation. Last, statins do not restrict the rates of plasma incorporation or oxidation of the ingested glucose.

Stair walking effects on feelings of energy and fatigue: Is 4-min enough for benefits?

Even low intensity exercise bouts of at least 15 min can improve feelings of energy (FOE) and reduce systolic blood pressure. However, little is known about the psychological outcomes of briefer exercise bouts, particularly for modes of exercise that are more intense than level walking, and readily available to many working adults. This study assessed the effects of a 4-min bout of stair walking on FOE and feelings of fatigue (FOF). Thirty-six young adult participants were randomized to either stair walking or seated control groups. All participants walked on level-ground from a laboratory to a nearby stairwell (~90 s) and were seated for 4 min before beginning their experimental condition. Stair-walking participants walked up and down one flight of 16 stairs at their own pace for 4 min, while control participants remained seated during that time. Participants walked back to the laboratory for post-condition assessments. Measures of blood pressure, heart rate, rated perceived exertion (RPE), and the intensity of feelings of mental energy, mental fatigue, physical energy, and physical fatigue were assessed pre-and post-condition. Separate one-way ANOVAs were conducted on change scores for all variables. The stair climbing group experienced significant increases in heart rate [F(1,34) = 13.167, p < 0.001] and RPE [F(1,34) = 93.844, p < 0.001] that were not observed in the seated control group. Four minutes of self-paced stair climbing resulted in small changes and non-significant differences within and between groups in blood pressure as well as FOE and FOF. Although a 4-min self-paced exercise bout can convey short-term physiological health benefits, a 4-min bout of self-paced indoor stair walking in a stairwell was insufficient to lower blood pressure or change subjective FOE and fatigue in a sample that exhibited better than typical FOE and FOF at the pre-test.

Repeated prolonged moderate-intensity walking exercise does not appear to have harmful effects on inflammatory markers in patients with inflammatory bowel disease

Background and objectives The role of exercise in the management of inflammatory bowel disease (IBD) is inconclusive as most research focused on short or low-intensity exercise bouts and subjective outcomes. We assessed the effects of repeated prolonged moderate-intensity exercise on objective inflammatory markers in IBD patients. Methods In this study, IBD patients (IBD walkers, n = 18), and a control group (non-IBD walkers, n = 19), completed a 30, 40 or 50 km walking exercise on four consecutive days. Blood samples were taken at baseline and every day post-exercise to test for the effect of disease on exercise-induced changes in cytokine concentrations. A second control group of IBD patients who did not take part in the exercise, IBD non-walkers (n = 19), was used to test for the effect of exercise on faecal calprotectin. Both IBD groups also completed a clinical disease activity questionnaire. Results Changes in cytokine concentrations were similar for IBD walkers and non-IBD walkers (IL-6 p = .95; IL-8 p = .07; IL-10 p = .40; IL-1β p = .28; TNF-α p = .45), with a temporary significant increase in IL-6 (p < .001) and IL-10 (p = .006) from baseline to post-exercise day 1. Faecal calprotectin was not affected by exercise (p = .48). Clinical disease activity did not change in the IBD walkers with ulcerative colitis (p = .92), but did increase in the IBD walkers with Crohn’s disease (p = .024). Conclusion Repeated prolonged moderate-intensity walking exercise led to similar cytokine responses in participants with or without IBD, and it did not affect faecal calprotectin concentrations, suggesting that IBD patients can safely perform this type of exercise.

Cardiovascular Autonomic Changes Following a Bout of Low-intensity Exercise in Recently Concussed and Healthy Athletes

Cardiovascular Autonomic Changes Following a Bout of Low-intensity Exercise in Recently Concussed and Healthy Athletes

Single bout of low-intensity exercise produces modestly favorable changes in glycemic and lipidemic profiles after ingestion of non-isoglucidic breakfasts.

The aim of this study was to investigate the acute effects of low-intensity exercise on the postprandial hormonal and metabolic milieu induced by breakfast consumption. Exercise began 100 min after the initiation of breakfast consumption and consisted of cycling at 40% of maximum oxygen uptake for 20 min. Three different breakfasts were used to elicit the postprandial state: B1 = skimmed milk (125 mL) and 30g corn flakes; B2 = skimmed milk (220 mL), 200 g apple, 30 g cocoa cream-filled sponge cake; B3 = skimmed milk (125 mL), 50 g bread, 150 g apple, and 15 g hazelnut and cocoa spread. Nineteen young healthy participants (8 M/11 F; body mass index 22.7 ± 0.5 kg/m2; age 31 ± 0.7 y) consumed the three breakfasts, as well as an oral glucose load (50-g oral glucose tolerance test), under either resting or exercise conditions, in a randomized-crossover fashion. Blood glucose, insulinemia, ghrelinemia, lipidemia, and satiety were measured throughout the studies. To evaluate the metabolic effects of exercise, the changes that glucose, insulin, ghrelin, free fatty acid exhibited in the interval 90 to 120 min were analyzed with a two-way repeated measures analysis of variance (factor 1: type of oral test; factor 2: resting/exercise condition). No interaction between the two factors was found for any of the examined variables. Light exercise produced a modest, significant decrease in blood glucose levels (P = 0.004) and a modest, significant increase in free fatty acid levels (P = 0.002) with respect to the resting condition. These findings suggest that short, mild exercise has beneficial effects on postprandial metabolism and this may have direct bearing on the issue of counteracting the epidemic rising of sedentary lifestyle of the general population.

Acute effects of high- and low-intensity exercise bouts on leukocyte counts

Background/ObjectiveIt is widely accepted that physical exercise may bring about changes in the immune system. Even acute bouts of exercise can alter the number and function of leukocytes, but the degree of white blood cell trafficking depends on the intensity and duration of exercise. The aim of this study was to analyze the acute and short-term effects of exercise intensity on leukocyte counts and leukocyte subsets. MethodsNine physically healthy, active young males (21.0 ± 1.9 years) underwent three experimental trials: high exercise intensity [80% peak oxygen consumption (VO2peak)], low exercise intensity (40% VO2peak), and the control condition (no exercise). Blood samples were collected prior to exercise, immediately after exercise, and 2 hours after exercise. Two-way analysis of variance for repeated measures was used to evaluate differences between the trials and the time-points, and to compare times within trials. ResultsThere was a greater increase in the leukocyte count after high-intensity exercise, compared to the control condition (p < 0.01) and low-intensity exercise (p < 0.01). This effect was still present 2 hours after passive recovery (p < 0.01). ConclusionWhen the same participants were submitted to different exercise intensities, the acute and short-term effects of exercise on white blood cells were intensity-dependent immediately after exercise (i.e., lymphocytosis and monocytosis) and 2 hours after passive recovery (i.e., neutrophilia).

Beta Endorphin and Alcohol Urge Responses in Alcoholic Patients Following an Acute Bout of Exercise

Objective: To examine the effects of low intensity exercise on beta endorphin (β-E) levels and urge for alcohol in alcoholic patients. Methods: Nine alcoholic patients (M= 41.2 + 6.7 yrs) and 9 healthy controls (M=38.2 + 10.7 yrs) exercised for 30 minutes at a low intensity (61.1 + 4.9 % of their maximum heart rate). Blood was collected prior to and immediately following exercise and was analyzed for a complete blood count (CBC), β-E and lactic acid. Furthermore, an alcohol urge questionnaire was filled by the subjects prior to and immediately following exercise. Results: Data analysis revealedthat β-E levels were significantly lower in alcoholic patients whereas exercise resulted in significant (p< .001) increases in β-E (pre: 1.57 + 0.39 pmol/L, post: 4.8 + 1.6 pmol/L) only in alcoholic patients. Lactic acid increased significantly in both groups. There was a 17% decrease in alcohol urge in alcoholic patients without however this difference being significant. No differences in the parameters assessed through the CBC were seen between the two groups whereas exercise resulted in significant increases in red blood cells, hemoglobin and hematocrit in both groups. Conclusion: These results indicate that a bout of low intensity exercise affects the endogenous opioids in alcoholic patients.

Masked hypertension is “unmasked” by low-intensity exercise blood pressure

Purpose: Masked hypertension (MH) independently predicts mortality but cannot be diagnosed from clinic blood pressure (BP) taken under resting conditions. We sought to determine if MH could be identified from BP taken during a single bout of low-intensity exercise. Methods. BP was recorded at rest and during brief low-level cycling exercise (60–70% of age-predicted maximal heart rate) in 75 untreated subjects with a hypertensive response to exercise (aged 54 ± 9 years). All subjects underwent 24-h ambulatory BP monitoring (ABPM) and MH was defined as clinic BP < 140/90 mmHg and ABPM BP ≥ 130/80 mmHg. Results. There were 42 (56%) patients with MH, and at rest systolic (SBP) was higher in subjects with MH compared with those without MH (127 ± 9 vs 120 ± 9 mmHg; p < 0.05). During exercise, MH subjects had significantly higher SBP (188 ± 22 vs 168 ± 15 mmHg; p < 0.05), with a greater change from baseline (61 ± 21 vs 48 ± 15 mmHg; p < 0.05). Low-level exercise SBP was independently associated with MH, and if ≥175 mmHg, identified MH with 74% sensitivity and 67% specificity (p < 0.001). Conclusion. MH can be identified in untreated individuals from low-intensity exercise SBP. Further research on the diagnostic value of BP during early phases of exercise stress testing is needed.

Investigation of MGF mRNA expression in patients with amyotrophic lateral sclerosis using parallel in vivo and in vitro approaches

In an animal model of ALS, intramuscular administration of MGF, the IGF-I Ec gene splice variant, improved muscle strength and increased both motor unit and motor neuron survival. Here we investigated whether there is a deficit in MGF production in the muscles of patients with ALS. We used complementary in vivo and in vitro techniques to study the IGF-I splice variant response of human muscle to exercise or mechanical stretch. We assessed the levels of MGF and IGF-IEa mRNA in muscle biopsy samples from healthy subjects and patients with ALS, before and after exercise. We used primary muscle cells to build three-dimensional collagen constructs and subjected them to a ramp stretch. Patients with ALS had similar baseline levels of MGF and IGF-IEa mRNA to healthy controls. No up-regulation was seen in either group within a short time of a single bout of low intensity exercise. Three-dimensional human muscle constructs also detected no response to a mechanical stretch from either control subjects or ALS. We conclude that the pathology of ALS does not include a deficit in baseline levels of MGF and IGF-IEa mRNA splice variants in muscle.

Ventilatory Expired Gas at Constant-Rate Low-Intensity Exercise Predicts Adverse Events and is Related to Neurohormonal Markers in Patients With Heart Failure

Background Ventilatory efficiency (VE/VCO 2 ratio) and the partial pressure of end-tidal carbon dioxide (P ETCO 2), obtained during moderate to high levels of physical exertion demonstrate prognostic value in heart failure (HF). The present investigation assesses the clinical utility of these variables during low-intensity exercise. Methods and Results One hundred and thirty subjects diagnosed with HF underwent a 2-minute, constant-rate treadmill session at 2 miles per hour. Both the VE/VCO 2 ratio and P ETCO 2 were recorded during exercise (30-second average) and their change (Δ) from rest. B-type and atrial natriuretic peptide (BNP and ANP) were also determined. Only P ETCO 2 and ΔP ETCO 2 emerged from the multivariate Cox regression. Receiver operating characteristic curve analysis revealed the prognostic classification schemes were significant with thresholds of </≥34 mm Hg (hazard ratio: 4.2, 95% CI: 2.2–8.0, P < .001) and </≥1 mm Hg (hazard ratio: 3.5, 95% CI: 1.9–6.6, P < .001) being optimal for P ETCO 2 and ΔP ETCO 2, respectively. Moreover, subjects with a P ETCO 2≥34 mm Hg had a significantly lower BNP (214.1 ± 431.9 vs. 1110.5 ± 1854.0 pg/mL, P=.005) and ANP (108.2 ± 103.6 vs. 246.2 ± 200.4 pg/mL, P < .001). Conclusions The results of this pilot study indicate ventilatory expired gas analysis during a short bout of low-intensity exercise may provide insight into prognosis and cardiac stability.

The effect of short-term exercise on plasma leptin levels in patients with anorexia nervosa

Plasma leptin concentrations are markedly reduced in malnourished patients with anorexia nervosa (AN). Whether the long-term underweight and low-fat stores affect the leptin response to exercise remains unknown. We investigated the effect of 45-minute cycle ergometer exercise (2 W kg −1 of lean body mass [LBM]) on plasma leptin, norepinephrine (NE), glycerol, and insulin levels in 10 patients with AN and in 15 healthy age-matched women (C). Plasma leptin levels immediately and 90 minutes after the exercise bout were significantly reduced compared with basal leptin levels in both AN and C groups ( P < .05). Compared with the control trial, leptin levels were significantly lower immediately and 90 minutes after exercise in the AN group ( P < .05) but not in the C group. Basal and exercise-induced plasma glycerol and NE levels did not differ significantly between the groups. Basal and exercise-induced plasma insulin levels were significantly lower in the AN group compared with the C group ( P < .05). In conclusion, we demonstrated that a single bout of low-intensity exercise significantly reduces plasma leptin levels in patients with AN. In healthy women, exercise had no effect on lowering leptin concentrations beyond the diurnal decrease that occurs in the absence of exercise. Neither NE nor insulin are responsible for the different response of leptin to exercise in AN.

Effects of one single bout of low-intensity exercise on postprandial lipaemia in type 2 diabetic men

Fighting type 2 diabetes and its high risk of CVD, lifestyle intervention with diet and exercise is of uttermost importance. Epidemiological studies strongly suggest an inverse association between increased physical activity, moderate alcohol drinking and the incidence of both type 2 diabetes and CVD. However, alcohol is known to increase postprandial lipaemia, a risk marker of CVD, and exercise to reduce postprandial lipaemia in healthy individuals. The aim of the present study was to investigate how type 2 diabetic men respond, in the postprandial period, to a single exercise session feasible to perform on a daily basis for type 2 diabetic men. The twelve participants ingested a test meal containing 100 g butter, 50 g carbohydrate, together with 40 g alcohol, at each meal test, imitating a social meal situation. Two protocols included exercise sessions with 40 min at 40% VO2max, one where they exercised 3.5 h after, and another the afternoon before the test meal. One protocol was without any exercise. No significant effect of low-intensity exercise on postprandial lipaemia following a fat-rich meal with alcohol was seen in the middle-aged type 2 diabetic men.

The effect of a single bout of brisk walking on postprandial lipemia in normolipidemic young adults

The purpose of this study was to examine the effect of one bout of low-intensity exercise on the lipemic response to a high-fat meal. Twelve (six women, six men) normolipidemic adults aged 25.8 ± 1.2 years (mean ± SEM) took part in two trials. In the exercise trial, subjects walked for 2 hours on a treadmill at 30.9% ± 1.6% of maximal oxygen uptake (VO 2 max) 15 hours before ingestion of the test meal. In the control trial, subjects rested the day before the test meal. After a 12-hour fast, blood samples were obtained by venous cannulation before ingestion and hourly after ingestion for 6 hours. Serum was analyzed for triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and HDL 2-C, apolipoproteins (apos) A-I and B, free fatty acids (FFA), free glycerol, glucose, and insulin. TG values were corrected for free glycerol. Fasting serum TG and peak TG concentrations were lower (Wilcoxon, P < .05) for the exercise trial than for the control trial (0.74 ± 0.03 v 0.92 ± 0.08 and 1.98 ± 0.18 v 2.59 ± 0.32 mmol · L −1, respectively). The total lipemic response (area under the TG/time curve, normalized to the 0-hour level) was 31% ± 7% lower in the exercise trial (4.28 ± 0.66 v 6.46 ± 1.08 mmol · L −1 · h, P < .01). No differences were found between trials in the other parameters. These results show that a single bout of low-intensity exercise reduces the extent of postprandial lipemia in normolipidemic young adults. One possible mechanism is enhanced lipoprotein lipase (LPL) activity in the exercised skeletal muscle.

Role of Fat Metabolism in Exercise

Fat and carbohydrate are the two major energy sources used during exercise. Either source can predominate, depending upon the duration and intensity of exercise, degree of prior physical conditioning, and the composition of the diet consumed in the days prior to a bout of exercise. Fatty acid oxidation can contribute 50 to 60 per cent of the energy expenditure during a bout of low intensity exercise of long duration. Strenuous submaximal exercise requiring 65 to 80 per cent of VO2 max will utilize less fat (10 to 45 per cent of the energy expended). Exercise training is accompanied by metabolic adaptations that occur in skeletal muscle and adipose tissue and that facilitate a greater delivery and oxidation of fatty acids during exercise. The trained state is characterized by an increased flux of fatty acids through smaller pools of adipose tissue energy. This is reflected by smaller, more metabolically active adipose cells in smaller adipose tissue depots. Peak blood concentrations of free fatty acids and ketone bodies are lower during and following exercise in trained individuals, probably due to increased capacity of the skeletal musculature to oxidize these energy sources. Trained individuals oxidize more fat and less carbohydrate than untrained subjects when performing submaximal work of the same absolute intensity. This increased capacity to utilize energy from fat conserves crucial muscle and liver glycogen stores and can contribute to increased endurance. Further benefits of the enhanced lipid metabolism accompanying chronic aerobic exercise training are decreased cardiac risk factors. Exercise training results in lower blood cholesterol and triglycerides and increased high density lipoprotein cholesterol. High-fat diets are not recommended because of their association with atherosclerotic heart disease. Recent evidence suggests that low-fat high-carbohydrate diets may increase blood triglycerides and reduce high density lipoproteins. This suggests that the chronic ingestion of diets that are extreme in their composition of either fat or carbohydrate should be approached with caution in health-conscious athletes, as well as in sedentary individuals.

A simple, accurate technique for predicting maximal aerobic power.

A simple, accurate technique for predicting maximal aerobic power.