Muscle hypertrophy in prediabetic men after 16 wk of resistance training
Resistance training of healthy young men typically results in muscle hypertrophy and a shift in vastus lateralis composition away from type IIx fibers to an increase in IIa fiber content. Our previous studies of 8 wk of resistance training found that many metabolic syndrome men and women paradoxically increased IIx fibers with a decrease in IIa fibers. To confirm the hypothesis that obese subjects might have muscle remodeling after resistance training very different from healthy lean subjects, we subjected a group of nine obese male volunteers to progressive resistance training for a total of 16 wk. In these studies, weigh...
Source: Journal of Applied Physiology - October 26, 2017 Category: Physiology Authors: Stuart, C. A., Lee, M. L., South, M. A., Howell, M. E. A., Stone, M. H. Tags: RESEARCH ARTICLE Source Type: research
Factors contributing to lower metabolic demand of eccentric compared with concentric cycling
This study compared muscle-tendon behavior, muscle oxygenation, and muscle activity between eccentric and concentric cycling exercise at the same work output to investigate why metabolic demand is lower during eccentric cycling than with concentric cycling. Eleven untrained men (27.1 ± 7.0 y) performed concentric cycling (CONC) and eccentric cycling (ECC) for 10 min (60 rpm) at 65% of the maximal concentric cycling power output (191 ± 45 W) 4 wk apart. During cycling, oxygen consumption (Vo2), heart rate (HR), vastus lateralis (VL) tissue total hemoglobin (tHb), and oxygenation index (TOI) were recorded, and ...
Source: Journal of Applied Physiology - October 26, 2017 Category: Physiology Authors: Penailillo, L., Blazevich, A. J., Nosaka, K. Tags: RESEARCH ARTICLE Source Type: research
Reproducibility of airway luminal size in asthma measured by HRCT
Brown RH, Henderson RJ, Sugar EA, Holbrook JT, Wise RA, on behalf of the American Lung Association Airways Clinical Research Centers. Reproducibility of airway luminal size in asthma measured by HRCT. J Appl Physiol 123: 876–883, 2017. First published July 13, 2017; doi:10.1152/japplphysiol.00307.2017.—High-resolution CT (HRCT) is a well-established imaging technology used to measure lung and airway morphology in vivo. However, there is a surprising lack of studies examining HRCT reproducibility. The CPAP Trial was a multicenter, randomized, three-parallel-arm, sham-controlled 12-wk clinical trial to assess the...
Source: Journal of Applied Physiology - October 26, 2017 Category: Physiology Authors: Brown, R. H., Henderson, R. J., Sugar, E. A., Holbrook, J. T., Wise, R. A., on behalf of the American Lung Association Airways Clinical Research Centers Tags: RESEARCH ARTICLE Source Type: research
Comparing anesthesia with isoflurane and fentanyl/fluanisone/midazolam in a rat model of cardiac arrest
This study shows the importance of anesthesia in experimental cardiac arrest studies as isoflurane raised coronary perfusion pressure during resuscitation, reduced time to return of spontaneous circulation, and increased arterial blood pressure in the post-cardiac arrest period. These effects on key outcome measures in cardiac arrest research are important in the interpretation of results from animal studies. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Secher, N., Malte, C. L., Tonnesen, E., Ostergaard, L., Granfeldt, A. Tags: RESEARCH ARTICLE Source Type: research
Bone microvascular flow differs from skin microvascular flow in response to head-down tilt
Loss of hydrostatic pressures in microgravity may alter skin and bone microvascular flows in the lower extremities and potentially reduce wound healing and bone fracture repair. The purpose of this study was to determine the rate at which skin and bone microvascular flows respond to head-down tilt (HDT). We hypothesized that microvascular flows in tibial bone and overlying skin would increase at different rates during HDT. Tibial bone and skin microvascular flows were measured simultaneously using photoplethysmography (PPG) in a total of 17 subjects during sitting (control posture), supine, 6° HDT, 15° HDT, and 30&...
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Howden, M., Siamwala, J. H., Hargens, A. R. Tags: RESEARCH ARTICLE Source Type: research
A study of clinical and physiological relations of daily physical activity in precapillary pulmonary hypertension
In this study, novel findings in a representative sample of patients with precapillary pulmonary hypertension link reduced daily walking activity, as measured by triaxial accelerometry, with compromised right ventricular and pulmonary vascular status, peripheral muscle oxygenation, and health-related quality of life, providing a preliminary insight into the physiological mechanisms and clinical predictors of daily physical activity in precapillary pulmonary hypertension. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Panagiotou, M., Johnson, M. K., Louvaris, Z., Baker, J. S., Church, A. C., Peacock, A. J., Vogiatzis, I. Tags: RESEARCH ARTICLE Source Type: research
Heat shock protein 90 contributes to cutaneous vasodilation through activating nitric oxide synthase in young male adults exercising in the heat
While the mechanisms underlying the control of cutaneous vasodilation have been extensively studied, there remains a lack of understanding of the different factors that may modulate cutaneous perfusion during an exercise-induced heat stress. We evaluated the hypothesis that heat shock protein 90 (HSP90) contributes to the heat loss response of cutaneous vasodilation via the activation of nitric oxide synthase (NOS) during exercise in the heat. In 11 young males (25 ± 5 yr), cutaneous vascular conductance (CVC) was measured at four forearm skin sites that were continuously treated with 1) lactated Ringer solution (co...
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Fujii, N., Zhang, S. Y., McNeely, B. D., Nishiyasu, T., Kenny, G. P. Tags: RESEARCH ARTICLE Source Type: research
Associations between motor unit action potential parameters and surface EMG features
In this study, we clarify the potential and limitations of interference EMG analysis to infer motor unit recruitment strategies with an experimental investigation of several concurrently active motor units and of the associated features of the surface EMG. For this purpose, we recorded high-density surface EMG signals during linearly increasing force contractions of the tibialis anterior muscle, up to 70% of maximal force. The recruitment threshold (RT), conduction velocity (MUCV), median frequency (MDFMU), and amplitude (RMSMU) of action potentials of 587 motor units from 13 individuals were assessed and associated with f...
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Del Vecchio, A., Negro, F., Felici, F., Farina, D. Tags: RESEARCH ARTICLE Source Type: research
Active sleep unmasks apnea and delayed arousal in infant rat pups lacking central serotonin
We report that rat pups deficient in central 5-HT (TPH2–/–) are profoundly more apneic in active sleep (AS) but not quiet sleep (QS). Unlike control pups, the arousal of TPH2–/– pups in air, CO2, and hypoxia was delayed in AS compared with QS. Thus for infants deficient in central 5-HT, the risk of SIDS may be higher in AS than in QS. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Young, J. O., Geurts, A., Hodges, M. R., Cummings, K. J. Tags: RESEARCH ARTICLE Source Type: research
Heat acclimation has a protective effect on the central but not peripheral nervous system
This study aimed to clarify the pathway mediating hyperthermia-induced alterations in neural drive transmission and determine if heat acclimation protects voluntary muscle activation and cognitive function in hyperthermic humans. Electrically evoked potentials (H reflex and M wave), executive function (special planning and working memory), and maximal voluntary isometric contractions (120 s) were assessed in 14 participants in control conditions [CON, 24°C, 40% relative humidity (RH)] and in a hyperthermic state (HYP, 44–50°C, 50% RH) on consecutive days in a counterbalanced order. Thereafter, participants we...
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Racinais, S., Wilson, M. G., Gaoua, N., Periard, J. D. Tags: RESEARCH ARTICLE Source Type: research
Different gene response to mechanical loading during early and late phases of rat Achilles tendon healing
This study investigates the direct effect of mechanical loading on gene expression during different healing phases in tendon healing. One isolated episode of mechanical loading was studied in otherwise unloaded healing tendons. This enabled us to study a time sequence, i.e., which genes were the first ones to be regulated after the loading episode. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Hammerman, M., Blomgran, P., Dansac, A., Eliasson, P., Aspenberg, P. Tags: RESEARCH ARTICLE Source Type: research
Effects of strict prolonged bed rest on cardiorespiratory fitness: systematic review and meta-analysis
The aim of this systematic review and meta-analysis [International Prospective Register of Systematic Reviews (PROSPERO) CRD42017055619] was to assess the effects of strict prolonged bed rest (without countermeasures) on maximal oxygen uptake (Vo2max) and to explore sources of variation therein. Since 1949, 80 studies with a total of 949 participants (>90% men) have been published with data on strict bed rest and Vo2max. The studies were conducted mainly in young participants [median age (interquartile range) 24.5 (22.4–34.0) yr]. The duration of bed rest ranged from 1 to 90 days. Vo2max declined linearly across b...
Source: Journal of Applied Physiology - October 24, 2017 Category: Physiology Authors: Ried-Larsen, M., Aarts, H. M., Joyner, M. J. Tags: RESEARCH ARTICLE Source Type: research
Automated quality control of forced oscillation measurements: respiratory artifact detection with advanced feature extraction
In this study, we propose an automated artifact removal approach based on the resistance against flow profile, applied to complete breaths. We report results obtained from data recorded from children and adults, with and without asthma. Our proposed method has 76% agreement with a human operator for the adult data set and 79% for the pediatric data set. Furthermore, we assessed the variability of respiratory resistance measured by FOT using within-session variation (wCV) and between-session variation (bCV). In the asthmatic adults test data set, our method was again similar to that of the manual operator for wCV (6.5 vs. 6...
Source: Journal of Applied Physiology - October 9, 2017 Category: Physiology Authors: Pham, T. T., Leong, P. H. W., Robinson, P. D., Gutzler, T., Jee, A. S., King, G. G., Thamrin, C. Tags: INNOVATIVE METHODOLOGY Source Type: research
Changes in brachial artery endothelial function and resting diameter with moderate-intensity continuous but not sprint interval training in sedentary men
Moderate-intensity continuous training (MICT) improves peripheral artery function in healthy adults, a phenomenon that reverses as continued training induces structural remodeling. Sprint interval training (SIT) elicits physiological adaptations similar to MICT, despite a lower exercise volume and time commitment; however, its effect on peripheral artery function and structure is largely unexplored. We compared peripheral artery responses to 12 wk of MICT and SIT in sedentary, healthy men (age = 27 ± 8 yr). Participants performed MICT (45 min of cycling at 70% peak heart rate; n = 10) or SIT (3 x 20-s "all out" cycl...
Source: Journal of Applied Physiology - October 9, 2017 Category: Physiology Authors: Shenouda, N., Gillen, J. B., Gibala, M. J., MacDonald, M. J. Tags: RESEARCH ARTICLE Source Type: research
The effects of RSR13 on microvascular PO2 kinetics and muscle contractile performance in the rat arterial ligation model of peripheral arterial disease
In conclusion, reduction of hemoglobin-oxygen affinity via RSR13 in AL increased PmvO2 and improved muscle contractile performance most likely via enhanced blood-muscle O2 diffusion.
NEW & NOTEWORTHY This is the first investigation to examine the effect of RSR13 (erythrocyte allosteric effector) on skeletal muscle microvascular oxygen partial pressure kinetics and contractile function using an arterial ligation model of peripheral arterial disease in experimental animals. The present results provide strong support for the concept that reducing hemoglobin-O2 affinity via RSR13 improved tibialis anterior muscle contracti...
Source: Journal of Applied Physiology - October 9, 2017 Category: Physiology Authors: Watanabe, A., Poole, D. C., Kano, Y. Tags: RESEARCH ARTICLE Source Type: research
