A chronic physical activity treatment in obese rats normalizes the contributions of ET-1 and NO to insulin-mediated posterior cerebral artery vasodilation
This study tested the hypotheses that obesity-induced decrements in insulin-stimulated cerebrovascular vasodilation would be normalized with acute endothelin-1a receptor antagonism and that treatment with a physical activity intervention restores vasoreactivity to insulin through augmented nitric oxide synthase (NOS)-dependent dilation. Otsuka Long-Evans Tokushima Fatty rats were divided into the following groups: 20 wk old food controlled (CON-20); 20 wk old free food access (model of obesity, OB-20); 40 wk old food controlled (CON-40); 40 wk old free food access (OB-40); and 40 wk old free food access+RUN (RUN-40; wheel-...
Source: Journal of Applied Physiology - April 18, 2017 Category: Physiology Authors: Olver, T. D., McDonald, M. W., Klakotskaia, D., Richardson, R. A., Jasperse, J. L., Melling, C. W. J., Schachtman, T. R., Yang, H. T., Emter, C. A., Laughlin, M. H. Tags: RESEARCH ARTICLE Source Type: research
Divergent endothelial function but similar platelet microvesicle responses following eccentric and concentric cycling at a similar aerobic power output
Endothelial function and microvesicle concentration changes after acute bouts of continuous eccentric exercise have not been assessed previously nor compared with concentric exercise at similar aerobic power outputs. This method of training may be useful among some clinical populations, but acute responses are not well described. As such, 12 healthy males completed 2 experimental sessions of either 45 min of eccentric or concentric cycling at a matched aerobic power output below the ventilatory threshold. Brachial artery vascular function was assessed throughout 5 min of forearm ischemia and 3 min thereafter, before and at...
Source: Journal of Applied Physiology - April 18, 2017 Category: Physiology Authors: Rakobowchuk, M., Ritter, O., Wilhelm, E. N., Isacco, L., Bouhaddi, M., Degano, B., Tordi, N., Mourot, L. Tags: RESEARCH ARTICLE Source Type: research
Assessment of cardiac fibrosis: a morphometric method comparison for collagen quantification
In conclusion, in contrast to the staining protocol, section thickness and the quantification method being used directly influence the estimated collagen content and thus, possibly, intergroup comparisons. EM in combination with stereology is a precise and sensitive method for collagen quantification if certain prerequisites are considered. For subtle fibrotic alterations, consideration of collagen localization may be necessary. Among LM methods, LM-stereology and automated image analysis are appropriate to quantify fibrotic changes, the latter depending on careful control of algorithm and comparable section staining.
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Source: Journal of Applied Physiology - April 18, 2017 Category: Physiology Authors: Schipke, J., Brandenberger, C., Rajces, A., Manninger, M., Alogna, A., Post, H., Mühlfeld, C. Tags: RESEARCH ARTICLE Source Type: research
Sublingual microcirculatory blood flow and vessel density in Sherpas at high altitude
This study tested the hypothesis that Sherpas exposed to hypobaric hypoxia on ascent to 5,300 m develop increased microcirculatory blood flow as a means of maintaining tissue oxygen delivery. Incident dark-field imaging was used to obtain images of the sublingual microcirculation from 64 Sherpas and 69 lowlanders. Serial measurements were obtained from participants undertaking an ascent from baseline testing (35 m or 1,300 m) to Everest base camp (5,300 m) and following subsequent descent in Kathmandu (1,300 m). Microcirculatory flow index and heterogeneity index were used to provide indexes of microcirculatory flow, while...
Source: Journal of Applied Physiology - April 18, 2017 Category: Physiology Authors: Gilbert-Kawai, E., Coppel, J., Court, J., van der Kaaij, J., Vercueil, A., Feelisch, M., Levett, D., Mythen, M., Grocott, M. P., Martin, D., Xtreme Everest 2 Research Group Tags: RESEARCH ARTICLE Source Type: research
Melatonin protects against uric acid-induced mitochondrial dysfunction, oxidative stress, and triglyceride accumulation in C2C12 myotubes
This study shows that hyperuricemia induces mitochondrial dysfunction and triglyceride accumulation in skeletal muscle. The findings may explain why hyperuricemia is an independent predictor of diabetes. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Maarman, G. J., Andrew, B. M., Blackhurst, D. M., Ojuka, E. O. Tags: RESEARCH ARTICLE Source Type: research
Measurement of the maximum oxygen uptake VO2max: VO2peak is no longer acceptable
The maximum rate of O2 uptake (i.e., Vo2max), as measured during large muscle mass exercise such as cycling or running, is widely considered to be the gold standard measurement of integrated cardiopulmonary-muscle oxidative function. The development of rapid-response gas analyzers, enabling measurement of breath-by-breath pulmonary gas exchange, has facilitated replacement of the discontinuous progressive maximal exercise test (that produced an unambiguous Vo2-work rate plateau definitive for Vo2max) with the rapidly incremented or ramp testing protocol. Although this is more suitable for clinical and experimental investig...
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Poole, D. C., Jones, A. M. Tags: REVIEW Source Type: research
Effects and prevalence of nonresponders after 12 weeks of high-intensity interval or resistance training in women with insulin resistance: a randomized trial
This study demonstrates that 12 wk of HIIT and RT have similar effects and NR prevalence to improve glucose control variables. However, significantly different NR prevalence were observed in other anthropometric, cardiovascular, strength, and endurance performance measurements. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Alvarez, C., Ramirez-Campillo, R., Ramirez-Velez, R., Izquierdo, M. Tags: RESEARCH ARTICLE Source Type: research
Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations
Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer’s recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, O�...
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Beck, O. N., Taboga, P., Grabowski, A. M. Tags: RESEARCH ARTICLE Source Type: research
Decreases in maximal oxygen uptake following long-duration spaceflight: Role of convective and diffusive O2 transport mechanisms
We have previously predicted that the decrease in maximal oxygen uptake (Vo2max) that accompanies time in microgravity reflects decrements in both convective and diffusive O2 transport to the mitochondria of the contracting myocytes. The aim of this investigation was therefore to quantify the relative changes in convective O2 transport (Qo2) and O2 diffusing capacity (Do2) following long-duration spaceflight. In nine astronauts, resting hemoglobin concentration ([Hb]), Vo2max, maximal cardiac output (QTmax), and differences in arterial and venous O2 contents (CaO2-CvO2) were obtained retrospectively for International Space...
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Ade, C. J., Broxterman, R. M., Moore, A. D., Barstow, T. J. Tags: RESEARCH ARTICLE Source Type: research
DNA methylation assessment from human slow- and fast-twitch skeletal muscle fibers
This study validates a low-DNA input reduced representation bisulfite sequencing method for human muscle biopsy samples to investigate the methylation patterns at a fiber type-specific level. These are the first fiber type-specific methylation data reported from human skeletal muscle and thus provide initial insight into basal state differences in myosin heavy chain I and IIa muscle fibers among young, healthy men. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Begue, G., Raue, U., Jemiolo, B., Trappe, S. Tags: INNOVATIVE METHODOLOGY Source Type: research
Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration
Hypohydration, or a body water deficit, is a common occurrence in athletes and recreational exercisers following the completion of an exercise session. For those who will undertake a further exercise session that day, it is important to replace water losses to avoid beginning the next exercise session hypohydrated and the potential detrimental effects on performance that this may lead to. The aim of this review is to provide an overview of the research related to factors that may affect postexercise rehydration. Research in this area has focused on the volume of fluid to be ingested, the rate of fluid ingestion, and fluid ...
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Evans, G. H., James, L. J., Shirreffs, S. M., Maughan, R. J. Tags: REVIEW Source Type: research
Restoration of thermoregulation after exercise
Performing exercise, especially in hot conditions, can heat the body, causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole body heat loss; a response mediated by temperature-sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body’s ability to dissipate heat during exercise. These include the activation of the body’s se...
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Kenny, G. P., McGinn, R. Tags: REVIEW Source Type: research
The cardiovascular system after exercise
Recovery from exercise refers to the time period between the end of a bout of exercise and the subsequent return to a resting or recovered state. It also refers to specific physiological processes or states occurring after exercise that are distinct from the physiology of either the exercising or the resting states. In this context, recovery of the cardiovascular system after exercise occurs across a period of minutes to hours, during which many characteristics of the system, even how it is controlled, change over time. Some of these changes may be necessary for long-term adaptation to exercise training, yet some can lead ...
Source: Journal of Applied Physiology - April 11, 2017 Category: Physiology Authors: Romero, S. A., Minson, C. T., Halliwill, J. R. Tags: REVIEW Source Type: research
Respiratory muscle blood flow during exercise: Effects of sex and ovarian cycle
Sex and ovarian cycle have been speculated to modify respiratory muscle blood flow control during exercise, but the findings are inconclusive. We tested the hypotheses that females would have higher respiratory muscle blood flow and vascular conductance (VC) compared with males during exercise and that this difference would be accentuated in proestrus vs. ovariectomized (OVA) females. Mean arterial pressure (carotid artery catheter) and respiratory muscle blood flow (radiolabeled microspheres) were measured during moderate-intensity (24 m/min, 10% grade) exercise in male (n = 9), female (n = 9), and OVA female (n = 7) rats...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Smith, J. R., Hageman, K. S., Harms, C. A., Poole, D. C., Musch, T. I. Tags: RESEARCH ARTICLE Source Type: research
Blood flow regulation and oxygen uptake during high-intensity forearm exercise
In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WRmax and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations.
NEW & NOTEWORTHY This study evaluated blood flow regulation and oxygen uptake during small muscle mass forearm exercise with high to maximal intensity. Despite utilizing only a fraction of cardiac output, blood flow reached a plateau at 80% of maximal work rate and regulated peak oxygen uptake. Furthermore, the results reve...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Nyberg, S. K., Berg, O. K., Helgerud, J., Wang, E. Tags: RESEARCH ARTICLE Source Type: research
