Different stress biomarkers sensitivity during acute treadmill running exercise in rats

The level of stress during acute or chronic exercise is important since higher levels of stress may impair homeostasis. The adrenal gland is an essential stress-responsive organ involved in the hypothalamic-pituitary-adrenal axis. The aim of the study was to analyze the sensitivity of different stress biomarkers of the adrenal gland during acute treadmill running at different intensities. Adult rats performed three 25 min running tests at velocities of 15, 20 and 25 m/min, for determination of maximum lactate steady state (MLSS). After obtaining individual MLSS animals were assigned to two groups: M, sacrificed after 25 minutes of exercise at MLSS, and AM, sacrificed after exercise at 25% above MLSS. For comparison, a control group C was sacrificed at rest. Blood corticosterone concentrations, as well, adrenal gland cholesterol and ascorbic acid concentrations were used as biomarkers. Serum corticosterone concentrations were higher after exercise in both M (1802,74±700,42) and AM (2027,96±724,94) groups when compared C group (467,11±262,12), but were not different as a function of exercise intensity. No difference in adrenal ascorbic acid (M=2,37±0,66; AM=2,11±0,50 and C=2,54±0,53) and cholesterol (M=1,04±0,12; AM=0,91±0,31 and C=1,15±0,40) levels were observed when the three groups were compared. Serum corticosterone concentrations showed to be sensitive to acute treadmill exercise intensity. On the other hand, ascorbic acid and cholesterol concentrations in adrenal were biomarkers not adequate to evaluate exercise stress in rats.

Effects of Jugular Vein Occlusion on Cardiovascular Parameters in Horses During Exercise on a Treadmill

The purpose of the present investigation was to examine the effects of unilateral and bilateral jugular vein occlusion by temporary surgical ligature on the heart rate and arterial and venous blood pressure in sedentary horses during progressive treadmill exercise. Six horses performed three exercise tests (ET). ET1, considered the control, was performed in horses without jugular occlusions. ET2 and ET3 were performed with unilateral and bilateral occlusion by temporary surgical ligature of the jugular veins, respectively. Heart rate, arterial pressure, and pressure of the occluded jugular vein were evaluated. Clinically, the horses presented apathy, head edema, congested mucous membranes, increased capillary refill time, and dysphagia. These signs were observed with the unilateral jugular vein occlusion and became more evident with the bilateral occlusion. Comparing ETs, no differences were observed in heart rate. However, jugular occlusions promoted a decrease in the mean arterial pressure and a severe increase in jugular pressure. Head edema caused by the jugular vein occlusion in the horses could interfere with the autonomic cardiovascular regulation of arterial blood pressure during exercise, likely leading to an impairment of tissue perfusion. Jugular occlusion, even unilateral, also causes severe head venous congestion, leading to venous hypertension that was aggravated by exercise, which could risk development of cerebral edema and neurological damage. The present results obtained from sedentary horses are preliminary data that lead us to suggest that sport horses presenting jugular occlusive thrombophlebitis, even unilateral, may be prevented from performing athletic activities. © 2013 Elsevier Inc. All rights reserved.

Reliability of peak running speeds obtained from different incremental treadmill protocols

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Treadmill Training Increases SIRT-1 and PGC-1 alpha Protein Levels and AMPK Phosphorylation in Quadriceps of Middle-Aged Rats in an Intensity-Dependent Manner

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of the best-designed graded exercise test to assess peak treadmill speed

This study examined the influence of different speed increments during treadmill exercise tests on peak treadmill speed (Vpeak) and its relationship with a 1-h treadmill running performance. 18 male recreational and amateur runners (10-km running pace: 10–15 km·h−1) performed, in an alternate order, 3 continuous incremental exercise tests with different speed increments (0.5, 1.0 and 2.0 km·h−1) on a motorized treadmill to determine Vpeak. Thereafter they undertook a 1-h time trial on a treadmill. Vpeak was determined as either (a) the highest speed that could be maintained for a complete minute (Vpeak-60 s), (b) the speed of the last complete stage (Vpeak-C), or (c) the speed of the last complete stage added to the product of the speed increment and the completed fraction of the incomplete stage (Vpeak-P). The Vpeak values were highly influenced by the different speed-incremented rates and the Vpeak-P determined during the protocol comprising speed increments of 1 km·h−1 presented the highest correlation with 1-h time trial performance (r=0.89). The results suggest that a protocol with speed increments comprising 1 km·h−1 and with a 3-min stage duration should be used as standard for the determination of Vpeak to assess aerobic fitness and predict endurance performance in recreational runners. Furthermore, the Vpeak-P should be used for the determination of Vpeak.

Reproducibility of heart rate and rating of perceived exertion values obtained from different incremental treadmill tests

Objective The present study aimed to examine the reproducibility of heart rate (HR) and rating of perceived exertion (RPE) values obtained during different incremental treadmill tests. Equipment and methods Twenty male, recreational, endurance-trained runners (10-km running pace: 10–15 km·h−1) performed, in a counterbalanced order, three continuous incremental exercise tests with different speed increments (0.5 km·h−1, 1 km·h−1 and 2 km·h−1). Thereafter, each participant performed the three tests again, maintaining the same order as before. The reproducibility of the HR and RPE values were analyzed for all protocols during submaximal intensities (8, 10, 12, and 14 km·h−1). In addition, it was examined the reproducibility of maximal HR (HRmax) and peak RPE (RPEpeak). Results The variability of both the HR and RPE values showed a tendency to decrease over the stages during the incremental test and was not or slightly influenced by the incremental test design. The HR at 14 km·h−1 and HRmax presented the highest reproducibility (CV < 2%). In contrast, the submaximal RPE values showed higher variability indices (i.e., CV > 5.0%). In conclusion, the HR values were highly reproducible during the stages of the incremental test, in contrast to the RPE values that presented limited reproducibility.

Ischaemia modified albumin in horses exercised at different intensities in treadmill

Ischaemia modified albumin (IMA) is considered a biomarker of myocardial ischaemia in humans in contrast to other biomarkers released when cardiac necrosis occurs. Little is known about release conditions of IMA in exercise and this is the first report in equine species. For this purpose, ten clinically healthy untrained horses were submitted to a high intensity test (HIT) followed by a low intensity test (LIT) seven days later. Blood samples were taken before, during and immediately after exercise, and 15 min and 30 min thereafter. Serum IMA, lactate and albumin, and plasma malondialdehyde (MDA) were determined. There were no significant changes in IMA concentration in any of the exercise tests. There was also a negative correlation between IMA and albumin levels in both tests, and between IMA and lactate levels in LIT, suggesting possible assay interferences. It was concluded that HIT and LIT did not promote significant changes in IMA concentration in horses under these conditions.

Validità e affidabilità nelle specifiche condizioni di camminata e corsa su treadmill, di un particolare prototipo di accelerometro da polso

Studio della validità e affidabilità dell'informazione scientifica, fornita in output, da un particolare prototipo di accelerometro da polso, denominato "MyBand" dell'azienda "IDT Technology". La validazione è stata fatta in termini di consumo calorico, secondo due tipi di analisi: - Criterion validity: confrontando il dato in uscita con quello ottenuto tramite calorimetria indiretta; - Concurrent validity: confrontando il dato in uscita con quello rilevato da un altro accelerometro, già scientificamente validato (MyWellness Key). E' stato sviluppato un protocollo di studi, suddiviso in sei step di camminata e corsa su treadmill, che è stato eseguito da 23 persone (13 maschi e 10 femmine). I dati in uscita sono stati studiati tramite grafici di correlazione e di Blan-Altman, per verificare quindi la validità e l'affidabilità del valore di consumo calorico fornito da "MyBand".

Caratterizzazione sperimentale di parametri spaziotemporali nella corsa su treadmill

Lo scopo della tesi è verificare se esiste nell’uomo una correlazione tra le velocità preferite di corsa\cammino e i parametri antropometrici, e inoltre dare un significato ai segnali acquisiti dall’analisi del passo tramite uno strumento in fase di sviluppo. Sono stati reclutati 20 soggetti mediamente allenati e suddivisi equamente per sesso. I soggetti sono stati sottoposti ad un protocollo di test motori su treadmill diviso in due parti. I dati del primo test sono stati acquisiti manualmente mentre i dati del secondo test sono stati acquisiti da uno strumento e inviati a remoto. L’elaborazione dei risultati di entrambi i test è stata effettuata utilizzando i software Microsoft Excell e Matlab R2010a. Dai dati è emerso un trend significativo per le velocità di corsa in funzione delle altezze, ma non per quelle di cammino. Per le seconde è stata invece riscontrata una netta differenza tra soggetti maschili e femminili che ha portato a classificare i due sessi separatamente. I parametri riguardanti l’analisi del passo del secondo test sono risultati qualitativamente accettabili e confrontabili con la letteratura, ma sarà necessaria una futura validazione sperimentale per la conferma scientifica.

Analisi cinematica dell'arto inferiore durante il cammino in acqua su treadmill

Analisi cinematica dell'arto inferiore durante il cammino in acqua su treadmill

A new standardized treadmill walking test requiring low motor skills in children aged 4-10 years

Exercise intolerance may be reported by parents of young children with respiratory diseases. There is, however, a lack of standardized exercise protocols which allow verification of these reports especially in younger children. Consequently the aims of this pilot study were to develop a standardized treadmill walking test for children aged 4-10 years demanding low sensorimotor skills and achieving high physical exhaustion. In a prospective experimental cross sectional pilot study, 33 healthy Caucasian children were separated into three groups: G1 (4-6 years, n = 10), G2 (7-8 years, n = 12), and G3 (9-10 years, n = 11). Children performed the treadmill walking test with increasing exercise levels up to peak condition with maximal exhaustion. Gas exchange, heart rate, and lactate were measured during the test, spirometry before and after. Parameters were statistically calculated at all exercise levels as well as at 2 and 4 mmol/L lactate level for group differences (Kruskal-Wallis H-test, alpha = 0.05; post hoc: Mann-Whitney U-test with Bonferroni correction alpha = 0.05/n) and test-retest differences (Wilcoxon-rank-sum test) with SPSS. The treadmill walking test could be demonstrated to be feasible with a good repeatability within groups for most of the parameters. All children achieved a high exhaustion level. At peak level under exhaustion condition only the absolute VO2 and VCO2 differed significantly between age groups. In conclusion this newly designed treadmill walking test indicates a good feasibility, safety, and repeatability. It suggests the potential usefulness of exercise capacity monitoring for children aged from early 4 to 10 years. Various applications and test modifications will be investigated in further studies.

The diagnostic value of a treadmill test in predicting lumbar spinal stenosis

Lumbar spinal stenosis is a frequent indication for spinal surgery. The predictive quality of treadmill testing and MRI for diagnostic verification is not yet clearly defined. Aim of the current study was to assess correlations between treadmill testing and MRI findings in the lumbar spine. Twenty-five patients with lumbar spinal stenosis were prospectively examined. Treadmill tests were performed and the area of the dural sac and neuroforamina was examined with MRI for the narrowest spinal segment. VAS and ODI were used for clinical assessment. The median age of the patients was 67 years. In the narrowest spinal segment the median area of the dural sac was 91 mm(2). The median ODI was 66 per cent. The median walking distance in the treadmill test was 70 m. The distance reached in the treadmill test correlated with the area of the dural sac (Spearman's rho = 0.53) and ODI (rho = -0.51), but not with the area of the neuroforamina and VAS. The distance reached in the treadmill test predicts the grade of stenosis in MRI but has a limited diagnostic importance for the level of clinical symptoms in lumbar spinal stenosis.