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Exercise Conditions (exercise + condition)
Selected AbstractsThe effects of acute exercise and high lactate levels on 35% CO2 challenge in healthy volunteersACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2002G. Esquivel Objective:, To test the possible antipanic effects of acute exercise in healthy volunteers exposed to an inhalation of 35% CO2 challenge. Method:, Twenty healthy subjects in a randomized separate group design, performed exercise in a bicycle ergometer reaching >6 mm of blood lactate and a control condition of minimal activity in the same fashion with no lactate elevation. Immediately afterwards an inhalation of a vital capacity using a mixture of 35% CO2/65% O2 through a mask was given on both conditions. Results:, Subjects under the exercise condition reported less panic symptoms than controls after a CO2 challenge on the diagnostic statistical manual-IV (DSM-IV) Panic Symptom List but no difference on the Visual Analogue Anxiety Scale. Conclusion:, Subjects under the exertion condition had lactate levels comparable with those of lactate infusions but an inhibitory rather than accumulative effect was seen when combined with a CO2 challenge. [source] The effects of acute exercise on attentional bias towards smoking-related stimuli during temporary abstinence from smokingADDICTION, Issue 11 2009Kate Janse Van Rensburg ABSTRACT Rationale Attentional bias towards smoking-related cues is increased during abstinence and can predict relapse after quitting. Exercise has been found to reduce cigarette cravings and desire to smoke during temporary abstinence and attenuate increased cravings in response to smoking cues. Objective To assess the acute effects of exercise on attentional bias to smoking-related cues during temporary abstinence from smoking. Method In a randomized cross-over design, on separate days regular smokers (n = 20) undertook 15 minutes of exercise (moderate intensity stationary cycling) or passive seating following 15 hours of nicotine abstinence. Attentional bias was measured at baseline and post-treatment. The percentage of dwell time and direction of initial fixation was assessed during the passive viewing of a series of paired smoking and neutral images using an Eyelink II eye-tracking system. Self-reported desire to smoke was recorded at baseline, mid- and post-treatment and post-eye-tracking task. Results There was a significant condition × time interaction for desire to smoke, F(1,18) = 10.67, P = 0.004, eta2 = 0.36, with significantly lower desire to smoke at mid- and post-treatment following the exercise condition. The percentage of dwell time and direction of initial fixations towards smoking images were also reduced significantly following the exercise condition compared with the passive control. Conclusion Findings support previous research that acute exercise reduces desire to smoke. This is the first study to show that exercise appears to also influence the salience and attentional biases towards cigarettes. [source] The effects of acute exercise on cognitive functioning and cigarette cravings during temporary abstinence from smokingHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 3 2008Kate Janse Van Rensburg Abstract Background Abstinence from smoking is associated with increased cravings, risk of accidents and self-reported poor concentration. A single exercise session can reduce cravings and self-reported poor concentration and can enhance cognitive performance among non-smokers. Objective To assess whether acute exercise impacts on the cognitive performance and cravings of abstaining smokers. Methods In a counterbalanced cross-over design, participants (n,=,23) did a 15,min passive or exercise condition, following cigarette abstinence. Cognitive functioning was measured by a computerised version of the Stroop colour-word interference task. Cravings were measured using the 10-item, 2-factor QSU-Brief and a single item for ,desire to smoke'. Measures were recorded at baseline, immediately post, 5, 10 and 15-min post treatment. Results A 2-way ANOVA showed no significant condition,×,time interaction for cognitive functioning. Significant interaction effects were found for desire to smoke, QSU Factor 1 (desire,behave) and 2 (desire,affect). Exercise reduced cravings for up to 15,min post treatment. Discussion Findings support previous research that acute exercise reduces cravings to smoke. Future research should determine if exercise can enhance other objective aspects of cognitive performance, and repeat the present study with a more homogeneous sample, in terms of Stroop performance. Conclusion This is the first study to show that exercise can reduce both factors of the QSU-Brief, but effects on cognitive functioning were not observed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Treadmill exercise in mice increases intestinal lymphocyte loss via apoptosisACTA PHYSIOLOGICA, Issue 3 2003L. Hoffman-Goetz Abstract Strenuous exercise is associated with a transient decline in circulating lymphocytes, possibly through increased apoptosis. Intestinal lymphocytes are important effector cells of intestinal immune function but have not been studied in relation to exercise. Aim:, The purpose of the present study was to examine the effect of exercise on intestinal lymphocyte phenotypes and apoptosis. Methods:, Female C57BL/6 mice (n = 112) were randomized to: (1) treadmill running (90 min, 32 m min,1, 8° grade) and killed immediately after exercise, (2) treadmill running and killed 2 h after exercise, (3) treadmill running and killed 24 h after exercise or (4) a non-exercised control condition with exposure to treadmill noise and vibration without running. Results:, Flow cytometry indicated that the total intestinal CD3+T (P < 0.01), CD4+T (P < 0.005), CD8+T (P < 0.05), pan-NK (P < 0.005) and CD19+B (P < 0.05) lymphocytes were significantly lower 24 h after exercise compared with non-exercised controls. Significantly more CD3+T (P < 0.05) and CD8+T (P < 0.05) intestinal lymphocytes stained positive for annexin V, a marker of apoptosis, at 24 h after exercise compared with intestinal lymphocytes from non-exercised controls. Plasma corticosterone and 8-isoprostane concentrations were also significantly higher immediately after exercise compared with other exercise conditions. Conclusion:, Acute strenuous exercise increases intestinal T (CD3+ and CD8+) lymphocyte loss and apoptosis. The extent to which the exercise-induced apoptosis in intestinal lymphocytes is mediated by increased glucocorticoid concentrations in the gastrointestinal tract will require further studies. [source] Screening for the calstabin-ryanodine receptor complex stabilizers JTV-519 and S-107 in doping control analysisDRUG TESTING AND ANALYSIS, Issue 1 2009Mario Thevis Abstract Recent studies outlined the influence of exercise on the stability of the skeletal muscle calstabin1-ryanodine receptor1-complex, which represents a major Ca2+ release channel. The progressive modification of the type-1 skeletal muscle ryanodine receptor (RyR1) combined with reduced levels of calstabin1 and phosphodiesterase PDE4D3 resulted in a Ca2+ leak that has been a suggested cause of muscle damage and impaired exercise capacity. The use of 1,4-benzothiazepine derivatives such as the drug candidates JTV-519 and S-107 enhanced rebinding of calstabin1 to RyR1 and resulted in significantly improved skeletal muscle function and exercise performance in rodents. Due to the fact that the mechanism of RyR1 remodelling under exercise conditions were proven to be similar in mice and humans, a comparable effect of JTV-519 and S-107 on trained athletes is expected, making the compounds relevant for doping controls. After synthesis of JTV-519, S-107, and a putative desmethylated metabolite of S-107, target compounds were characterized using nuclear magnetic resonance spectroscopy and electrospray ionization (ESI),high-resolution/high-accuracy Orbitrap mass spectrometry. Collision-induced dissociation pathways were suggested based on the determination of elemental compositions of product ions and H/D-exchange experiments. The most diagnostic product ion of JTV-519 was found at m/z 188 (representing the 4-benzyl-1-methyl piperidine residue), and S-107 as well as its desmethylated analog yielded characteristic fragments at m/z 153 and 138 (accounting for 1-methoxy-4-methylsulfanyl-benzene and 4-methoxy-benzenethiol residues, respectively). The analytes were implemented in existing doping control screening procedures based on liquid chromatography, multiple reaction monitoring and simultaneous precursor ion scanning modes using a triple quadrupole mass spectrometer. Validation items such as specificity, recovery (68,92%), lower limit of detection (0.1,0.2 ng/mL), intraday (5.2,18.5%) and interday (8.7,18.8%) precision as well as ion suppression/enhancement effects were determined. Copyright © 2009 John Wiley & Sons, Ltd. [source] Influence of track surface on the equine superficial digital flexor tendon loading in two horses at high speed trotEQUINE VETERINARY JOURNAL, Issue 3 2009N. Crevier-Denoix Summary Reasons for performing study: Although track surfaces are a risk factor of tendon injuries, their effects on tendon loading at high speed are unknown. Using a noninvasive ultrasonic technique, it is now possible to evaluate the forces in the superficial digital flexor tendon (SDFT) in exercise conditions. Objectives: To compare the effects of an all-weather waxed track (W) vs. a crushed sand track (S), on the SDFT loading in the trotter horse at high speed. Methods: Two trotter horses were equipped with the ultrasonic device (1 MHz ultrasonic probe, fixed on the palmar metacarpal area of the right forelimb). For each trial, data acquisition was made at 400 Hz and 10 consecutive strides were analysed. In each session, the 2 track surfaces were tested in a straight line. The speed was imposed at 10 m/s and recorded. The right forelimb was also equipped with a dynamometric horseshoe and skin markers. The horse was filmed with a high-speed camera (600 Hz); all recordings were synchronised. Statistical differences were tested using the GLM procedure (SAS; P<0.05). Results: Maximal tendon force was significantly lower on W compared with S. In addition to maximal force peaks around mid-stance, earlier peaks were observed, more pronounced on S than on W, at about 13%(horse 2) and 30% (both horses) of the stance phase. Comparison with kinematic data revealed that these early peaks were accompanied by plateaux in the fetlock angle-time chart. For high tendon forces, the tendon maximal loading rate was significantly lower on W than on S. Conclusions and potential clinical relevance: The all-weather waxed track appears to induce a lesser and more gradual SDFT loading than crushed sand. The SDFT loading pattern at high speed trot suggests proximal interphalangeal joint movements during limb loading. [source] The hypoxic threshold for maximum cardiac performance in rainbow trout Oncorhynchus mykiss (Walbaum) during simulated exercise conditions at 18° CJOURNAL OF FISH BIOLOGY, Issue 3 2007L. M. Hanson Perfused rainbow trout Oncorhynchus mykiss hearts exposed to simulated exercise conditions (hypoxia, hyperkalemia and acidosis) at 18° C experienced complete failure of maximum cardiac performance at oxygen tensions <5·6 kPa and partial failure at <6·7 kPa. This hypoxic threshold, which occurred in the presence of maximal adrenergic stimulation (500 nM adrenaline), is unusually high compared with previous results at a colder acclimation temperature. Cardiac failure was primarily due to significant decreases (P < 0·05) in heart rate rather than cardiac stroke volume at all hypoxia levels tested. [source] The Effect of Fatigue on the Timing of Electrical Stimulation-Evoked Muscle Contractions in People with Spinal Cord InjuryNEUROMODULATION, Issue 3 2004Peter J. Sinclair PhD Abstract This study investigated the activation dynamics of electrical stimulation-evoked muscle contractions performed by individuals with spinal cord injury (SCI). The purpose was to determine whether electrical stimulation (ES) firing patterns during cycling exercise should be altered in response to fatigue-induced changes in the time taken for force to rise and fall with ES. Seven individuals with SCI performed isometric contractions and pedaled a motorized cycle ergometer with stimulation applied to the quadriceps muscles. Both exercise conditions were performed for five minutes while the patterns of torque production were recorded. ES-evoked knee extension torque fell by 75% under isometric conditions, and the rate of force rise and decline decreased in proportion to torque (r = 0.91, r = 0.94, respectively). There was no change in the time for torque to rise to 50% of maximum levels. The time for torque to decline did increase slightly, but only during the first minute of exercise. Cycling power output fell approximately 50% during the five minutes of exercise, however, there was no change in the time taken for torque to rise or fall. The magnitude of ES-evoked muscle torques decline substantially with fatigue, however, the overall pattern of torque production remained relatively unchanged. These results suggest there is no need to alter stimulation firing patterns to accommodate fatigue during ES-evoked exercise. [source] Noninvasive Activity-based Control of an Implantable Rotary Blood Pump: Comparative Software Simulation StudyARTIFICIAL ORGANS, Issue 2 2010Dean M. Karantonis Abstract A control algorithm for an implantable centrifugal rotary blood pump (RBP) based on a noninvasive indicator of the implant recipient's activity level has been proposed and evaluated in a software simulation environment. An activity level index (ALI),derived from a noninvasive estimate of heart rate and the output of a triaxial accelerometer,forms the noninvasive indicator of metabolic energy expenditure. Pump speed is then varied linearly according to the ALI within a defined range. This ALI-based control module operates within a hierarchical multiobjective framework, which imposes several constraints on the operating region, such as minimum flow and minimum speed amplitude thresholds. Three class IV heart failure (HF) cases of varying severity were simulated under rest and exercise conditions, and a comparison with other popular RBP control strategies was performed. Pump flow increases of 2.54, 1.94, and 1.15 L/min were achieved for the three HF cases, from rest to exercise. Compared with constant speed control, this represents a relative flow change of 30.3, 19.8, and ,15.4%, respectively. Simulations of the proposed control algorithm exhibited the effective intervention of each constraint, resulting in an improved flow response and the maintenance of a safe operating condition, compared with other control modes. [source] | ||||||||||