Low-intensity exercise improves quality of life in patients with Crohn's disease.

OBJECTIVE: This study examines the effects of a low-intensity walking program on the quality of life in patients with Crohn's disease. DESIGN: Patients were randomized into exercise and nonexercise groups for a prospective study. SETTING: Patients were recruited at the inflammatory bowel disease outpatient clinic at the London Health Science Center, London, Ontario. PATIENTS: Thirty-two adult patients met the inclusion criteria of (1) mildly active disease or disease in remission, (2) habitual physical activity of less than 2 times per week of vigorous activity, (3) not anticipating change of dose or type of medication for Crohn's disease, and (4) no history of cardiovascular disease. All 32 patients who entered the study completed the 3-month study. INTERVENTION: Patients performed low-intensity walking at an interval of 3 times per week for a duration of 3 months. Each walking session lasted for 30 minutes. MAIN OUTCOME MEASUREMENTS: The Inflammatory Bowel Disease Questionnaire, the Inflammatory Bowel Disease Stress Index, and the Harvey-Bradshaw Simple Index were used as outcome. Survey measurements were recorded at 1-month intervals on commencement of the walking program. RESULTS: Patients in the exercise group experienced a statistically significant (P < 0.05) improvement in quality of life in all 3 of the outcome measurement questionnaires with no detrimental effects in terms of disease activity. CONCLUSION: A low-intensity walking program may have a beneficial effect in patients with Crohn's disease and improve their quality of life with no exacerbations in disease symptoms.     

Psychological skills training improves exercise performance in the heat

INTRODUCTION: Fatigue occurs earlier when working at corresponding exercise intensities in hot compared with cool conditions. Psychological skills training (PST) can modify the responses evoked by thermal stimuli such as the respiratory responses on immersion to cold water. This study tested the hypothesis that a 4-d PST package would significantly increase the distance covered during 90 min of running in the heat. METHOD: Eighteen subjects completed three maximal-effort runs (R1, R2, R3) of 90 min in the heat (30 degrees C; 40% RH). After R2, subjects were matched and randomly allocated to either a control group (CG) or psychological skills group (PSG). Between R2 and R3, the CG (N = 8) continued their normal activities, and the PSG (N = 10) received PST to help them tolerate unpleasant sensations arising from exercising in the heat, and to suppress the temptation to lower their work intensity. Key measures include distance covered, .VO2, skin (T(sk)) and aural temperature (T(au)), RPE, sweat production and evaporation, interleukin-6 (IL-6), and prolactin (PRL) in whole blood. RESULTS: The distances covered in the CG did not differ between runs. In the PSG, there were no differences in the distance run between R1 and R2, but they ran significantly farther in R3 (8%; 1.15 km); there were no between-group differences. There were no significant differences between R1 and R3 in peak T(au), T(sk), sweat volumes, IL-6, and PRL (P > 0.05) in either group. CONCLUSION: PST suppressed the temptation to reduce exercise intensity during R3. It is concluded that PST can improve running performance in the heat. The precise mechanisms underpinning these improvements are unclear; however, their implications for unblinded experimental design are not.     

Concurrent brain endurance training improves endurance exercise performance

ObjectivesMental fatigue impairs endurance exercise. Brain endurance training (BET) – engaging in cognitively fatiguing tasks during exercise - can develop resilience to mental fatigue and improve physical performance over physical training alone. The mechanism for this effect is unknown.This experiment examines if BET enhances performance over physical training and investigates potential underlying physiological mechanisms.DesignA mixed design randomised control trial.MethodsPre- and post-testing: 36 participants completed dynamic rhythmic muscular endurance handgrip tasks requiring generation of as much force as possible once a second for 300 s, performed under 3 counterbalanced conditions: following 600 s of a 2-back memory/attention task (subsequent); while performing a 2-back task (concurrent); and on its own (solo). Cardiac activity, electromyographic forearm activity, pre-frontal cerebral haemodynamics (near infrared spectroscopy), and force were recorded. Training: Participants (randomised to a Control or BET group) completed 24 (6 weeks) submaximal hand contractions sessions. The BET group also completed concurrent cognitive tasks (2-back, Stroop). Measures of motivation, physical and mental exertion and mental fatigue were collected throughout.ResultsEndurance performance, across the 3 tasks, improved more following BET (32%) than Control (12%) (p < 0.05). The better performance following BET occurred with a higher pre-frontal oxygenation during the post-training physical tasks over time relative to Control (p < 0.05).ConclusionsConcurrent BET improved endurance performance over physical training alone. This was accompanied by a training-induced maintenance of pre-frontal oxygenation, suggestive of reduced mental effort during physical activity.     

Low-intensity training dissociates metabolic from aerobic fitness

This study investigated the effect of prolonged whole-body low-intensity exercise on blood lipids, skeletal muscle adaptations and aerobic fitness. Seven male subjects completed a 32-day crossing of the Greenland icecap on cross-country skies and before and after this arm or leg cranking was performed on two separate days and biopsies were obtained from arm and leg muscle, and venous blood was sampled. During the crossing, subjects skied for 342+/-42 min/day and body mass was decreased by 7.1+/-0.7 kg. Peak leg oxygen uptake (4.6+/-0.2 L/min) was decreased (P<0.05) by 7% whereas peak arm oxygen uptake (3.0+/-0.2 L/min) remained unchanged. Total and low-density lipoprotein cholesterol (5.0+/-0.2 and 3.20.2 mmol/L) were decreased by 8% and 20%, respectively. Muscle beta-hydroxy-acyl-CoA dehydrogenase activity was increased with 22% in arm (P=0.08) and remained unchanged in leg muscle. Hormone sensitive lipase activity was similar in arm and leg muscle prior to the expedition and was not significantly affected by the crossing. In conclusion, an improved blood lipid profile and thus metabolic fitness was present after prolonged low-intensity training and this occurred in spite of a decreased aerobic fitness and an unchanged arm and leg muscle hormone-sensitive lipase activity.     

Aerobic exercise training improves physical performance of patients with binge-eating disorder

The aim of this study was to investigate the combined effects of aerobic exercise training and traditional treatment on body mass index (BMI) and aerobic capacity compared to the traditional treatment alone in patients with binge-eating disorder (BED). Fourteen BED patients were divided into Intervention Group (IG, n = 6) and Control Group (CG, n = 8). All patients participated into the weekly multidisciplinary program. In addition, IG underwent an aerobic exercise-training period of 6 months. At baseline and after 6 months of intervention, both groups underwent measurements of BMI and six-minute walk test (6MWT). BMI reduced in both groups (47.2 ± 5.5  and 42.7 ± 5.1 kg/m² in IG PRE and IG POST, respectively; p < 0.01; 46.6 ± 6.9 and 44.3 ± 6.1 kg/m² in CG PRE and CG POST, respectively; p < 0.01), but IG obtained a greater reduction than CG. Indeed, a BMI reduction of ?4.50 kg/m² in IG occurred while in CG decreased by ?2.30 kg/m² (p < 0.05). The IG improved the 6MWT (435.9 ± 106.2 and 519.1 ± 151.5 m in IG PRE and IG POST, respectively; p < 0.01). In addition, the CG improved 6MWT (455.5 ± 114.9 and 502.5 ± 110.7 m in CG PRE and CG POST, respectively; p < 0.01) probably because of the influence of diet and changes in body composition, even though the difference did not achieve statistical significance. Changes induced by the combined intervention were significantly greater than traditional treatment alone, suggesting that the addition of physical exercise constitutes a novel potential therapeutic approach in eating disorders.     

Low-intensity exercise, vascular occlusion, and muscular adaptations

The study investigated the effects of low-intensity exercise on muscular fitness when combined with vascular occlusion. Nineteen college male and female students performed two sets of a 5-min step exercise using a 12-inch bench three times per week for 5 weeks. During the step exercise, blood flow to one leg was restricted (vascular occlusion) with a blood pressure cuff, while the other leg was not occluded. Muscular strength of the occluded leg was significantly increased over the nonoccluded leg (p < 0. 05). Muscular endurance and muscle mass were improved after 5 weeks of training (p < 0.05); however, the changes between the two legs were not significantly different (p > 0.05). Exercise with vascular occlusion has the potential to be an alternative form of training to promote muscular strength.     

Haemorheology in exercise and training

Disruption of the normal rheological properties of blood is considered an independent risk factor for cardiovascular disease and plays a significant role in the aetiology of atherothrombogenesis. The acute increase in whole blood viscosity may unfavourably affect the microcirculatory blood flow and oxygen delivery to the tissues. It is universally accepted that exercise and physical activity performed on a regular basis has health benefits. However, the effects of exercise on the rheological properties of blood have not received much research attention. Recent, limited evidence indicates that the viscosities of whole blood and plasma increase in response to a variety of exercise protocols. The increase in whole blood viscosity is mainly attributed to an increase in haematocrit and plasma viscosity, whereas the deformability and aggregability of red blood cells remain unaltered. The increases in plasma viscosity and haematocrit have been ascribed to exercise-induced haemoconcentration as a result of fluid transfer from the blood to the interstitial spaces. The haemorheological changes associated with strenuous exercise appear to be linked with enhanced oxidative stress and depletion of antioxidant capacity, and that may affect oxygen delivery and availability to the tissues.Although significant advances have been made in many areas of exercise haematology, the long-term effects of endurance training on blood rheology have been very briefly examined and the exact effect of training has not as yet been determined. Available cross-sectional and longitudinal studies indicate that the blood of endurance athletes is more dilute and this has been attributed to an expansion of blood volume, particularly plasma volume as a result of training. The low haematocrit values in trained athletes represent a hydration condition rather than iron stores deficiency. It has been suggested that this hypervolaemia and blood dilutional effect of endurance training may be advantageous for heat dissipation and greater cardiac stroke volume and lower heart rates during exercise. Enhanced blood fluidity also facilitates oxygen delivery to the exercising muscles because of a reduced resistance to blood flow within the microcirculation. Furthermore, the increase in plasma volume may contribute to the body water pool and help offset dehydration. The influence of strength and power training on blood rheology is not known. The physiological mechanisms responsible for and the functional consequences of the haemorheological changes associated with exercise to a large extent remain speculative. The paradox of haematocrit and blood rheology in exercise and training warrants additional studies. Likewise, further investigations are necessary to determine the possible link between overtraining and blood rheological profiles.     

Cardiorespiratory exercise training in children

Definitive statements concerning the cardiorespiratory effects of exercise training in children cannot be made. Few carefully controlled and well-defined exercise training studies including important cardiorespiratory variables have been conducted. Generally, it appears that the response to training in pubescent and postpubescent children is not different from what is observed in adults.     

Vibration training improves balance in unstable ankles

Functional ankle instability (FAI) is a common condition following ankle injury characterised by increased risk of injury. Ankle sprains are a common acute form of injury suffered in dancing and loss of balance can affect not only risk of injury risk but also performance aesthetics. Whole body vibration training (WBVT) is a new rehabilitation method that has been linked with improving balance and muscle function. 38 female dancers with self reported unilateral FAI were randomly assigned in 2 groups: WBVT and control. Absolute centre of mass (COM) distribution during single leg stance, SEBT normalised research distances and Peroneus longus mean power frequency (f(med)) where measured pre and post 6-week intervention. There was a significant improvement in COM distribution over the 6 weeks from 1.05 ± 0.57 to 0.33 ± 0.42 cm2 (P<0.05), and 4 of the 8 planes of direction in the SEBT Ant, Antlat, Med and Antmed from 77.5 ± 7.1 to 84.1 ± 5.8% (P<0.05) compared to control groups during the course of the 6 week training intervention. There was no evidence of improvement in peroneus longus (f(med)) over time (P=0.915) in either group. WBVT improved static balance and SEBT scores amongst dancers exhibiting ankle instability but did not affect peroneus longus muscle fatigue.     

Dietary salt restriction improves pulmonary function in exercise-induced asthma

PURPOSE: Exercise-induced asthma (EIA) occurs in approximately 90% of persons with asthma. The mechanism has not been delineated. Epidemiological studies have suggested that dietary salt may play a role in airway responsiveness. Therefore, the purpose of this study was to determine the influence of both elevated and restricted salt diets on pulmonary function in subjects with EIA. METHODS: Eight subjects with EIA and eight subjects without EIA (control) participated in a double-blind crossover study. Pulmonary function was determined pre- and post-exercise challenge before and after 2 wk on a normal salt, sodium chloride, diet (NSD), a low salt diet (LSD), and a high salt diet (HSD). A 1-wk washout occurred between diets. RESULTS: Diet had no effect on preexercise pulmonary function values in either group and had no effect on postexercise pulmonary function values in control subjects. However, LSD improved and HSD worsened postexercise pulmonary function values in EIA subjects. Forced expiratory volume in 1 s (FEV1) decreased by at least 10% in EIA subjects with exercise. In EIA subjects, FEV1 decreased by 14+/-6% on LSD, 20+/-7% on NSD, and 24+/-6% on HSD at 15 min postexercise. Similar patterns were observed for forced vital capacity and peak expiratory flow rates. Although LSD did not normalize pulmonary function in EIA, it did improve it. CONCLUSIONS: These data suggest that individuals with EIA might benefit from lower salt diets.     

Blood hemostasis in exercise and training

Formation of the blood clot is a slow but normal physiological process occurring as a result of the activation of blood coagulation pathways. Nature's guard against unwanted blood clots is the fibrinolytic enzyme system. In healthy people, there is a delicate dynamic balance between blood clot formation and blood clot dissolution. Available evidence suggests that exercise and physical training evoke multiple effects on blood hemostasis in normal healthy subjects and in patients. A single bout of exercise is usually associated with a transient increase in blood coagulation as evidenced by a shortening of activated partial thromboplastin time (APTT) and increased Factor VIII (FVIII). The rise in FVIII is intensity dependent and continues into recovery. The effects of acute exercise on plasma fibrinogen have yielded conflicting results. Thus, the issue of whether exercise-induced blood hypercoagulability in vitro mirrors an in vivo thrombin generation and fibrin formation remains disputable. Exercise-induced enhancement of fibrinolysis has been repeatedly demonstrated using a wide range of exercise protocols incorporating various exercise intensities and durations. Moderate exercise appears to enhance blood fibrinolytic activity without a concomitant activation of blood coagulation mechanisms, whereas, very heavy exercise induces simultaneous activation of blood fibrinolysis and coagulation. The increase in fibrinolysis is due to a rise in tissue-type plasminogen activator (tPA) and decrease in plasminogen activator inhibitor (PAI). The mechanism of exercise-induced hyperfibrinolysis is poorly understood, and the physiological utility of such activation remains unresolved. Strenuous exercise elicits a transient increase in platelet count, but there are conflicting results concerning the effect of exercise on platelet aggregation and activation. Few comprehensive studies exist concerning the influence of exercise training on blood hemostasis, making future investigation necessary to identify whether there are favorable effects of exercise training on blood coagulation, fibrinolysis, and platelet functions.     

Inspiratory muscle training improves rowing performance

PURPOSE: To investigate the effects of a period of resistive inspiratory muscle training (IMT) upon rowing performance. METHODS: Performance was appraised in 14 female competitive rowers at the commencement and after 11 wk of inspiratory muscle training on a rowing ergometer by using a 6-min all-out effort and a 5000-m trial. IMT consisted of 30 inspiratory efforts twice daily. Each effort required the subject to inspire against a resistance equivalent to 50% peak inspiratory mouth pressure (PImax) by using an inspiratory muscle training device. Seven of the rowers, who formed the placebo group, used the same device but performed 60 breaths once daily with an inspiratory resistance equivalent to 15% PImax. RESULTS: The inspiratory muscle strength of the training group increased by 44 +/- 25 cm H2O (45.3 +/- 29.7%) compared with only 6 +/- 11 cm H2O (5.3 +/- 9.8%) of the placebo group (P < 0.05 within and between groups). The distance covered in the 6-min all-out effort increased by 3.5 +/- 1.2% in the training group compared with 1.6 +/- 1.0% in the placebo group (P < 0.05). The time in the 5000-m trial decreased by 36 +/- 9 s (3.1 +/- 0.8%) in the training group compared with only 11 +/- 8 s (0.9 +/- 0.6%) in the placebo group (P < 0.05). Furthermore, the resistance of the training group to inspiratory muscle fatigue after the 6-min all-out effort was improved from an 11.2 +/- 4.3% deficit in PImax to only 3.0 +/- 1.6% (P < 0.05) pre- and post-intervention, respectively. CONCLUSIONS: IMT improves rowing performance on the 6-min all-out effort and the 5000-m trial.     

Exercise training improves vasoreactivity in the knee artery

Physical activity has been shown to enhance endothelial function of central and peripheral vascular beds. The primary purpose of the present study was to test the hypothesis that a short-term exercise training program would result in enhanced endothelium-dependent vasorelaxation of a major artery supplying blood flow to the knee joint, the middle genicular artery. Female Yucatan miniature swine were randomly assigned into exercise trained (n=7) or sedentary (n=7) groups. Exercise trained pigs underwent a daily exercise training program on treadmills for 7 days. In vitro assessment of vasorelaxation was determined in a dose response manner by administrating increasing doses of 3 different dilators; adenosine diphosphate, bradykinin, and sodium nitroprusside. The role of nitric oxide synthase and cyclooxygenase pathways in vasomotor responses was evaluated with specific inhibitors using nitro-L-arginine methyl ester and indomethacin incubation, respectively. The results of this investigation indicate that adenosine and bradykinin-induced endothelium-dependent vasorelaxation were significantly enhanced in middle genicular artery from exercise trained pigs (p<0.05). Endothelium-independent vasorelaxation was not altered with exercise training as determined by the response to sodium nitroprusside. The findings of the present investigation indicate that short-term exercise training enhances endothelial function of middle genicular artery through adaptations in the nitric oxide synthase and by non-nitric oxide synthase, non-cyclooxygenase pathways.     

Aerobic exercise training improves the role of high-density lipoprotein antioxidant and reduces plasma lipid peroxidation in type 2 diabetes mellitus

In this study, we analyzed the effect of aerobic exercise training (AET) and of a single bout of exercise on plasma oxidative stress and on antioxidant defenses in type 2 diabetes mellitus (DM) and in healthy control subjects (C). DM and C did not differ regarding triglycerides, high-density lipoprotein cholesterol (HDL-c), insulin, and HOMA index at baseline and after AET. To measure the lag time for low-density lipoprotein (LDL) oxidation (LAG) and the maximal rate of conjugated diene formation (MCD), participants' plasma HDL(2) and HDL(3) were incubated with LDL from pooled healthy donors' plasma. In the presence of HDL(3), both LAG and MCD were similar in C and DM, but only in DM did AET improve LAG and reduce MCD. In the presence of HDL(2), the lower baseline LAG in DM equaled C after AET. MCD was unchanged in DM after AET, but was lower than C only after AET. Furthermore, after AET plasma thiobarbituric acid-reactive substances were reduced only in DM subjects. Despite not modifying the total plasma antioxidant status and serum paraoxonase-1 activity in both groups, AET lowered the plasma lipid peroxides, corrected the HDL(2), and improved the HDL(3) antioxidant efficiency in DM independent of the changes in blood glucose, insulin, and plasma HDL concentration and composition.