Physical Exercise In Humans Research Articles

Oxytocin and cortisol concentrations in urine and saliva in response to physical exercise in humans

BackgroundWhile peripheral markers of endogenous oxytocin and glucocorticoid release are widely employed in psychological and behavioural research, there remains uncertainty regarding the effectiveness of saliva and urine samples in accurately capturing fluctuating hormone levels in response to relevant stimuli. In addition, it is unclear whether and under which conditions, urinary concentrations correlate with salivary levels of oxytocin and cortisol. MethodsIn the present study, two groups of healthy adult male and female participants (N=43) provided heart rate, saliva, and urine samples before and after exercising at different durations and intensities (3 ×10 min of running vs. 60 min of running). Effects of age, gender, cycle phase, and previous running experience were considered in the statistical analyses. Concentrations of oxytocin and cortisol were analysed in both saliva, and urine using validated assays. ResultsRunners of both groups had significantly increased oxytocin concentrations in urine and saliva after running than before. Oxytocin in saliva was elevated after 10 min and peaked after 30 min of running. Only participants of the long-running group showed an increase in urinary cortisol concentrations following exercise (and only after 90 min of stimulus onset), and neither group had a significant increase in salivary cortisol levels. Oxytocin rise in urine and saliva from basal to post-run was strongly and significantly correlated, as was cortisol rise from basal to post-rest, but no correlations between absolute hormone concentrations were found for oxytocin. ConclusionsOur results show that both urine and saliva are useful body fluids that can provide meaningful results when measuring oxytocin and cortisol concentrations after a physical stimulus. While temporal resolution may be better with salivary sampling as higher sampling frequency is possible, signal strength and robustness were better in urinary samples. Importantly, we report a strong correlation between the magnitude of change in oxytocin and cortisol concentrations in urine and saliva following physical exercise, but no correlations between absolute oxytocin concentrations in the two substrates.

Changes to intraocular pressure and systemic blood pressure in dogs during moderate treadmill exercise - a short communication

Physical exercise in humans induces changes in intraocular pressure, relating to the type and intensity of the workload. The purpose of the present study was to evaluate the variations in intraocular pressure and arterial blood pressure in dogs that underwent physical exercise on a treadmill. Thirty dogs were submitted to physical exercise consisting of walking (15 minutes), trotting (20 minutes), and walking (10 minutes). The intraocular pressure, blood pressure and pulse rate were recorded for each dog before starting the treadmill exercise, immediately after it ended, and after 20 minutes of passive recovery. Two-way repeated analysis of variance measurement showed the significant effect of treadmill exercise (P≤0.01) on intraocular pressure, pulse rate and diastolic blood pressure. No significant changes were observed to systolic blood pressure. Intraocular pressure and diastolic blood pressure decreased significantly during the passive recovery, and were strongly related. The pulse rate was significantly lower during the passive recovery. Although the mechanism determining the reduction in intraocular pressure during exercise remains not fully understood, our results suggest that it is strongly related to variations in arterial blood pressure.

Mild Physical Activity Does Not Improve Spatial Learning in a Virtual Environment.

It is well-established that physical exercise in humans improves cognitive functions, such as executive functions, pattern separation, and working memory. It is yet unknown, however, whether spatial learning, long known to be affected by exercise in rodents, is also affected in humans. In order to address this question, we recruited 20 healthy young male adults (18–30 years old) divided into exercise and control groups (n = 10 in each group). The exercise group performed three sessions per week of mild-intensity aerobic exercise for 12 weeks, while the control group was instructed not to engage in any physical activity. Both groups performed maximal oxygen uptake (VO2max) tests to assess their cardiovascular fitness at baseline and every 4 weeks through the 12 weeks of the training program. The effects of mild aerobic exercise were tested on performance in two different virtual reality (VR)-based spatial learning tasks: (1) virtual Morris water maze (VMWM) and (2) virtual Radial arm water maze (VRAWM). Subjects were tested in both tasks at baseline prior to the training program and at the end of 12 weeks training program. While the mild-intensity aerobic exercise did not affect subjects' VO2max parameters, mean time to anaerobic threshold increased for the exercise group compared with control. No effect was observed, however, on performance in the VMWM or VRAWM between the two groups. Based on these results, we suggest that mild-intensity aerobic exercise does not improve spatial learning and memory in young, healthy adults.

Effects of Physical Exercise on Autophagy and Apoptosis in Aged Brain: Human and Animal Studies.

The aging process is characterized by a series of molecular and cellular changes over the years that could culminate in the deterioration of physiological parameters important to keeping an organism alive and healthy. Physical exercise, defined as planned, structured and repetitive physical activity, has been an important force to alter physiology and brain development during the process of human beings' evolution. Among several aspects of aging, the aim of this review is to discuss the balance between two vital cellular processes such as autophagy and apoptosis, based on the fact that physical exercise as a non-pharmacological strategy seems to rescue the imbalance between autophagy and apoptosis during aging. Therefore, the effects of different types or modalities of physical exercise in humans and animals, and the benefits of each of them on aging, will be discussed as a possible preventive strategy against neuronal death.

Left Ventricular Adaptations in Herding Dogs

Background: Athlete’s heart syndrome comprises a set of functional and anatomic cardiac changes secondary to intense and prolonged physical exercise in humans and animals. The heart adapts to the type of activity performed, and Doppler echocardiography is the best tool for identifying these changes. Speckle tracking echocardiography (STE) has provided new data on cardiovascular adaptations secondary to physical exercise in humans, information that conventional echocardiography cannot provide. Although physical activity and work in dogs are well documented, there are few studies on cardiovascular adaptations secondary to exercise in dogs, and no studies to date evaluated these adaptations using STE.Materials, Methods &Results:A total of 31 dogs of the Border Collie and OvelheiroGaúchoBrasileiro breeds were divided into two groups: a herding group (HG, n = 15), which performed herding activity five to six times a week for at least 4 months, and a sedentary group (SG, n = 16), with no history of physical activity in the past twelve months. All dogs were previously subjected to electrocardiography and blood pressure measurement. After that, the animals underwent echocardiographic examination at rest at a single time point. The data were analyzed by two-way multivariate analysis of variance (ANOVA) at a level of significance of 5% (P < 0.05) and a trend at 90% (P < 0.1). The dogs of the HG had higher values for left-ventricular end-systolic diameter (LVESD) and systolic volume (SV), and lower values for left-ventricular myocardial performance index (Tei index) and systolic septal movement. STE results indicated that the HG presented lower values for strain and strain rate in some myocardial segments in the radial, circumferential, longitudinal, and transverse directions.Discussion:The increase in LVESD is justified by the increase in preload (volume) required to meet the increased oxygen demand, whereas SV is directly related to the Frank-Starling mechanism. The lower Tei index in the HG indicates better systolic-diastolic performance, explained by a shorter isovolumetric relaxation time and isovolumetric contraction time and by an increase in left ventricular (LV) ejection time. Similar results were not observed in LV systolic wall motion. Therefore, we believe that the most likely explanation is a higher systolic efficiency, associated with lower energy demand at rest. According to STE criteria, the lower strain and strain rate in the HG in some myocardial segments in all directions suggest less need for myocardial deformation and lower deformation velocity in order to maintain systolic function. In conclusion, conventional echocardiography and STE were complementary and fundamental to understand cardiovascular adaptations in herding dogs.

Post-stroke BDNF Concentration Changes Following Physical Exercise: A Systematic Review.

Background: Research over the last two decades has highlighted the critical role of Brain-derived neurotrophic factor (BDNF) in brain neuroplasticity. Studies suggest that physical exercise may have a positive impact on the release of BDNF and therefore, brain plasticity. These results in animal and human studies have potential implications for the recovery from damage to the brain and for interventions that aim to facilitate neuroplasticity and, therefore, the rehabilitation process.Purpose: The aim of this study was to carry out a systematic review of the literature investigating how aerobic exercises and functional task training influence BDNF concentrations post-stroke in humans and animal models.Data Sources: Searches were conducted in PubMed (via National Library of Medicine), SCOPUS (Elsevier), CINAHL with Full Text (EBSCO), MEDLINE 1946—present with daily updates (Ovid) and Cochrane.Study Selection: All of the database searches were limited to the period from January, 2004 to May, 2017.Data Extraction: Two reviewers extracted study details and data. The methodological quality of the studies that used animal models was assessed using the ARRIVE Guidelines, and the study that evaluated human BDNF was assessed using the PEDro Scale.Data Synthesis: Twenty-one articles were included in this review. BDNF measurements were performed systemically (serum/plasma) or locally (central nervous system). Only one study evaluated human BDNF concentrations following physical exercise, while 20 studies were experimental studies using a stroke model in animals. A wide variation was observed in the training protocol between studies, although treadmill walking was the most common type of intervention among the studies. Studies were of variable quality: the studies that used animal models scored from 8/20 to 15/20 according to the ARRIVE Guidelines. The only study that evaluated human subjects scored 5/10 according to the PEDro scale and, which indicates a quality classified as “fair”.Conclusions: The results of the current systematic review suggest that aerobic exercise promotes changes in central BDNF concentrations post-stroke. On the other hand, BDNF responses following functional exercises, such as reaching training and Constraint Induced Movement Therapy (CIMT), seem to be still controversial. Given the lack of studies evaluating post-stroke BDNF concentration following physical exercise in humans, these conclusions are based on animal work.

Acute physical exercise in humans enhances reconsolidation of emotional memories

Increasing evidence suggests that when a memory is reactivated through retrieval, it becomes temporarily vulnerable to environmental or pharmacological manipulation, which can consequently update or strengthen the memory. Physical exercise has been shown to modulate the maintenance of fear memories in animals following memory reactivation. This study investigated the effect of intense exercise in modulating the reconsolidation of trauma memories. Fifty-four undergraduate students watched a trauma film depicting the aftermath of a highway car crash. Two days later, participants engaged in either (a) 20–25min of incremental cycling following a memory reactivation induction (Reactivation/Exercise), (b) 20–25min of mild cycling (Reactivation/No Exercise) following memory reactivation, or (c) 20–25min of incremental cycling but no memory reactivation (No Reactivation/Exercise). Saliva samples were collected to index salivary amylase and cortisol at baseline and post activity. Participants completed memory questionnaires relating to declarative and intrusive memory recall two days after memory reactivation. Reactivation/Exercise participants recalled more central details of the trauma film relative to other participants. Increased cortisol predicted better total memory recall in the Reactivation/Exercise, but not in the other conditions. These findings suggest that intense exercise during the period of memory reactivation enhances subsequent trauma memory, and provides human evidence consistent with recent findings of exercise-induced fear reconsolidation in animals.

Gender differences in cardiovascular functions during exercise: a brief review

Exercise is a major challenge for the cardiovascular apparatus, since it has to provide adequate oxygen supply to exercising muscles and to guarantee arterial blood pressure regulation. Several adjustments, such as heart rate increase, contractility enhancement, and venous return modulation are made to accomplish this task. Furthermore, regular physical training induces several physiological adaptations due to an increase in parasympathetic and a decrease in sympathetic tone and to chronic increases in cardiac pre-load and after-load. There are gender-related physiological and morphological differences in the cardiovascular adjustments and adaptations to physical exercise in humans. In this review, we briefly summarize these differences. Moreover, differences in ECG pattern between sexes are discussed.

Coronary and muscle blood flow during physical exercise in humans; heterogenic alliance.

In this review, we present the relation between power generation capabilities and pulmonary oxygen uptake during incremental cycling exercise in humans and the effect of exercise intensity on the oxygen cost of work. We also discuss the importance of oxygen delivery to the working muscles as a factor determining maximal oxygen uptake in humans. Subsequently, we outline the importance of coronary blood flow, myocardial oxygen uptake and myocardial metabolic stability for exercise tolerance. Finally, we describe mechanisms of endothelium-dependent regulation of coronary and skeletal muscle blood flow, dysregulation of which may impair exercise capacity and increase the cardiovascular risk of exercise.

Differential regulation of circadian melatonin rhythm and sleep-wake cycle by bright lights and nonphotic time cues in humans.

Our previous study demonstrated that physical exercise under dim lights (<10 lux) accelerated reentrainment of the sleep-wake cycle but not the circadian melatonin rhythm to an 8-h phase-advanced sleep schedule, indicating differential effects of physical exercise on the human circadian system. The present study examined the effects of bright light (>5,000 lux) on exercise-induced acceleration of reentrainment because timed bright lights are known to reset the circadian pacemaker. Fifteen male subjects spent 12 days in temporal isolation. The sleep schedule was advanced from habitual sleep times by 8 h for 4 days, which was followed by a free-run session. In the shift session, bright lights were given during the waking time. Subjects in the exercise group performed 2-h bicycle running twice a day. Subjects in the control kept quiet. As a result, the sleep-wake cycle was fully entrained by the shift schedule in both groups. Bright light may strengthen the resetting potency of the shift schedule. By contrast, the circadian melatonin rhythm was phase-advanced by 6.9 h on average in the exercise group but only by 2.0 h in the control. Thus physical exercise prevented otherwise unavoidable internal desynchronization. Polysomnographical analyses revealed that deterioration of sleep quality by shift schedule was protected by physical exercise under bright lights. These findings indicate differential regulation of sleep-wake cycle and circadian melatonin rhythm by physical exercise in humans. The melatonin rhythm is regulated primarily by bright lights, whereas the sleep-wake cycle is by nonphotic time cues, such as physical exercise and shift schedule.

Interview with Michael Ristow

Interview with Michael Ristow on his highly cited paper on his highly cited paper: Ristow M, Zarse K, Oberbach A, Klöting N, Birringer M, Kiehntopf M, Stumvoll M, Kahn CR, Bl?her M. "Antioxidants prevent health-promoting effects of physical exercise in humans". Proc Natl Acad Sci U S A. 2009 May 26; 106(21):8665-70. By January 2012, "Antioxidants prevent health-promoting effects of physical exercise in humans" was cited more than 177 times. At the time of the interview it was 125 times so it is ranked as number 5 among 100,000 papers on aging in 2009.

Dietary nitrate – a slow train coming

Dietary nitrate – a slow train coming

Erythrocyte membrane fluidity and indices of plasmatic oxidative damage after acute physical exercise in humans

Optimal levels of membrane fluidity are essential for numerous cell functions including cell growth, solute transport and signal transduction. Since exercise enhances free radical production, our aim was to evaluate in healthy male subjects the effects of an acute bout of maximal and submaximal exercise on the erythrocyte membrane fluidity and its possible relation to the oxidative damage overproduction due to exercise. Subjects (n = 34) performed three cycloergometric tests: a continuous progressive exercise, a strenuous exercise until exhaustion and an acute bout of exercise at an intensity corresponding to 70% of maximal work capacity for 30 min. Venous blood samples were collected before and immediately after these exercises. Erythrocyte membrane fluidity was assessed by fluorescence spectroscopy. Plasma malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) concentrations and carbonyl content of plasmatic proteins were used as an index of lipid and protein oxidation, respectively. Exercise produced a dramatic drop in the erythrocyte membrane fluidity as compared to resting time, but this was not accompanied by significant changes in the plasmatic MDA and 4-HDA concentrations. The highest erythrocyte membrane rigidity was detected immediately after strenuous exercise until exhaustion was performed. Protein carbonyl levels were higher after exhaustive exercises than at rest. Continuous progressive and strenuous exercises until exhaustion, but not submaximal workload, resulted in a significant enhanced accumulation of carbonylated proteins in the plasma. These findings are consistent with the idea that exercise exaggerates oxidative damage, which may contribute, at least partially, to explain the rigidity in the membrane of the erythrocytes due to acute exercise.

Exercise‐induced metabolic perturbation: all roads lead to Rome

Exercise‐induced metabolic perturbation: all roads lead to Rome

Antioxidants prevent health-promoting effects of physical exercise in humans

Antioxidants prevent health-promoting effects of physical exercise in humans

Antioxidants prevent health-promoting effects of physical exercise in humans

Exercise promotes longevity and ameliorates type 2 diabetes mellitus and insulin resistance. However, exercise also increases mitochondrial formation of presumably harmful reactive oxygen species (ROS). Antioxidants are widely used as supplements but whether they affect the health-promoting effects of exercise is unknown. We evaluated the effects of a combination of vitamin C (1000 mg/day) and vitamin E (400 IU/day) on insulin sensitivity as measured by glucose infusion rates (GIR) during a hyperinsulinemic, euglycemic clamp in previously untrained (n = 19) and pretrained (n = 20) healthy young men. Before and after a 4 week intervention of physical exercise, GIR was determined, and muscle biopsies for gene expression analyses as well as plasma samples were obtained to compare changes over baseline and potential influences of vitamins on exercise effects. Exercise increased parameters of insulin sensitivity (GIR and plasma adiponectin) only in the absence of antioxidants in both previously untrained (P < 0.001) and pretrained (P < 0.001) individuals. This was paralleled by increased expression of ROS-sensitive transcriptional regulators of insulin sensitivity and ROS defense capacity, peroxisome-proliferator-activated receptor gamma (PPARgamma), and PPARgamma coactivators PGC1alpha and PGC1beta only in the absence of antioxidants (P < 0.001 for all). Molecular mediators of endogenous ROS defense (superoxide dismutases 1 and 2; glutathione peroxidase) were also induced by exercise, and this effect too was blocked by antioxidant supplementation. Consistent with the concept of mitohormesis, exercise-induced oxidative stress ameliorates insulin resistance and causes an adaptive response promoting endogenous antioxidant defense capacity. Supplementation with antioxidants may preclude these health-promoting effects of exercise in humans.

Counterpoint: In health and in a normoxic environment, V̇o2 max is not limited primarily by cardiac output and locomotor muscle blood flow

Counterpoint: In health and in a normoxic environment, V̇<scp>o</scp>_{2 max} is not limited primarily by cardiac output and locomotor muscle blood flow

Oabain-Like Compound Changes Rapidly on Physical Exercise in Humans and Dogs

To the Editor: The article by Bauer et al1 attempts to add further credence to the suggestion that ouabain or a ouabain-like compound is secreted in mammals. The results indicate that under conditions of stress, in this case exercise, there is a dramatic increase in the production of immunologically assayed ouabain. In the studied athletes, this increase was up to 36-fold when expressed as endogenous ouabain immunoreactivity and an 18-fold increase when assayed by inhibition of the sodium pump. Cessation of exercise resulted in a fall in the concentration of ouabain-like compounds with a half-life of ≈3 to 5 minutes, and it …

Ouabain-Like Compound Changes Rapidly on Physical Exercise in Humans and Dogs

Ouabain, an inhibitor of the sodium pump, has been identified as a constituent of bovine adrenal glands. We were interested whether the release of this cardiotonic steroid is stimulated by physical exercise. Hence, athletes and healthy dogs were subjected to ergometry. Ouabain-like compound (OLC) was measured in venous blood by enzyme-linked immunosorbent assay as well as by (86)Rb+ uptake inhibition (as ouabain equivalents). OLC increased in venous blood of athletes after 15 minutes of ergometry from 2.5+/-0.5 to 86.0+/-27.2 nmol/L (n=51; P<0.001), as did the concentration of a circulating inhibitor of the sodium pump from 7.3+/-1.7 to 129.8+/-51 nmol/L (ouabain equivalents, P<0.05). Half-maximal increase in heart rate and systolic blood pressure occurred at 5.1+/-1.2 nmol/L and at 30+/-1 nmol/L OLC, respectively. On rest, OLC decreased in humans and dogs with a half-life of 3 to 5 minutes. In beagles exposed to moderate exercise on a treadmill for 13 minutes, levels of OLC increased 46-fold (from 3.7+/-0.8 to 166.9+/-91.8 nmol/L; n=6; P<0.005). This effect was suppressed when the dogs had been treated for 3 weeks with the beta1-adrenergic receptor blocker atenolol or the angiotensin-converting enzyme inhibitor benazepril. We conclude that OLC changes rapidly during exercise and is under the control of norepinephrine and angiotensin II.

Pivalic acid-induced carnitine deficiency and physical exercise in humans

To study the effect of carnitine depletion on physical working capacity, healthy subjects were administered pivaloyl-conjugated antibiotics for 54 days. The mean carnitine concentration in serum decreased from 35.0 to 3.5 μmol / L, and in muscle from 10 to 4.3 μmol/g noncollagen protein (NCP). Exercise tests were performed before and after 54 days' administration of the drug. At submaximal exercise, there was a slight increase in the concentration of 3-hydroxybutyrate in serum; presumably caused by decreased fatty acid oxidation in the liver. There was also a decreased consumption of muscle glycogen, indicating decreased glycolysis in the skeletal muscle. The muscle presumably had enough energy available, since there was no significant decrease in the concentration of adenosine triphosphate (ATP) and creatine phosphate during exercise. The work at maximal oxygen uptake (V o 2max) and the maximal heart rate were reduced. Since V o 2max is considered dependent on heart function, carnitine depletion seemed to affect cardiac function.