Journal of Applied Physiology (J APPL PHYSIOL )

Publisher: American Physiological Society (1887- ), American Physiological Society

Description

The Journal of Applied Physiology publishes original papers that deal with diverse areas of research in applied physiology, especially those emphasizing adaptive and integrative mechanisms. Adaptive physiology includes 1) inherent adaptations such as those related to development, aging, and pathophysiological conditions and 2) adaptations to the external environment such as those occurring with exercise, microgravity, hypoxia, hypo- and hyperbaria, and hypo- and hyperthermic conditions. Integrative physiology includes 1) horizontal integration across organ systems and 2) vertical integration from molecule to cell to organ. In all areas of applied physiology, the use of cutting-edge techniques including molecular and cellular biology is strongly encouraged.

  • Impact factor
    3.48
    Show impact factor history
     
    Impact factor
  • 5-year impact
    4.16
  • Cited half-life
    0.00
  • Immediacy index
    0.52
  • Eigenfactor
    0.05
  • Article influence
    1.24
  • Website
    Journal of Applied Physiology website
  • Other titles
    Journal of applied physiology (Bethesda, Md.: 1985), Journal of applied physiology
  • ISSN
    8750-7587
  • OCLC
    11603017
  • Material type
    Periodical, Internet resource
  • Document type
    Journal / Magazine / Newspaper, Internet Resource

Publisher details

American Physiological Society

  • Pre-print
    • Author cannot archive a pre-print version
  • Post-print
    • Author cannot archive a post-print version
  • Conditions
    • NIH, Wellcome Trust, HHMI, MRC and BBSRC authors will on their behalf have the Publisher's version/PDF deposited in PubMed Central for release 12 months after publication
    • Publisher's version/PDF cannot be used
  • Classification
    ​ white

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Mandibular advancement (MA) increases upper airway (UA) patency and decreases collapsibility. Furthermore, MA displaces the hyoid bone in a cranial-anterior direction, which may contribute to MA associated UA improvements via redistribution of peripharyngeal tissue stresses (extra-luminal tissue pressure, ETP). In the current study, we examined effects of MA on ETP distributions, deformation of the peripharyngeal tissue surface (UA geometry) and hyoid bone position. We studied thirteen supine, anaesthetized, tracheostomized, spontaneously breathing, adult male New Zealand white rabbits. Graded MA was applied from 0 to ~4.5 mm. ETP was measured at six locations distributed throughout three UA regions: tongue, hyoid and epiglottis. Axial computed tomography images of the UA (nasal choanae to glottis) were acquired and used to measure lumen geometry (UA length; regional cross-sectional area) and hyoid displacement. MA resulted in non-uniform decreases in ETP (greatest at tongue region), ranging from -0.11 (-0.15 to -0.06) to -0.82 (-1.09 to -0.54) cmH2O/mm MA [linear mixed-effects model slope (95% confidence interval)], across all sites. UA length decreased by -0.5 (-0.8 to -0.2) %/mm accompanied by non-uniform increases in cross-sectional area (greatest at hyoid region) ranging from 7.5 (3.6 - 11.4) to 18.7 (14.9 - 22.5) %/mm. The hyoid bone was displaced in a cranial-anterior direction by 0.42 (0.36 - 0.44) mm/mm MA. In summary, MA results in non-uniform changes in peripharyngeal tissue pressure distributions and lumen geometry. Displacement of the hyoid bone with MA may play a pivotal role in redistributing applied MA loads, thus modifying tissue stress/deformation distributions and determining resultant UA geometry outcomes.
    Journal of Applied Physiology 12/2014;
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    ABSTRACT: Reference proteins (RP) or the total protein (TP) loaded is used to correct for uneven loading and/or transfer in Western Blotting. However, the signal sensitivity and the influence of physiological conditions may question the normalization methods. Therefore, the use of three widely used reference proteins (β-actin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and α-tubulin), as well as TP loaded measured by Stain-Free technology (SF) as normalization tool were tested. This was done using skeletal muscle samples from men subjected to physiological conditions often investigated in applied physiology where the intervention has been suggested to impede normalization (ageing, muscle atrophy and different muscle fiber type composition). The linearity of signal and the methodological variation coefficient was obtained. Furthermore, the inter- and intra-individual variation in signals obtained from SF and RP was measured in relation to ageing, muscle atrophy and different muscle fiber type composition respectively. A stronger linearity of SF and β-actin compared to GAPDH and α-tubulin was observed. The methodological variation was relatively low in all four methods (4-11%). Protein level of β-actin and GAPDH was lower in older men compared to young men. In conclusion, β-actin, GAPDH, and α-tubulin may not be used for normalization in studies that include subjects with a large age difference. In contrast, the RPs may not be affected in studies that include muscle wasting and differences in muscle fiber type. The novel SF technology adds lower variation to the results compared to the existing methods for correcting for loading inaccuracy in Western Blotting of human skeletal muscle in applied physiology.
    Journal of Applied Physiology 11/2014; in Press.
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    ABSTRACT: Post-exercise protein ingestion increases whole-body and muscle protein anabolism in adults. No study has specifically investigated the combined effects of exercise and protein ingestion on protein metabolism in healthy, physically active children. Under 24h dietary control, thirteen (7 males, 6 females) active children (~11y age; 39.3±5.9 kg) consumed an oral dose of [15N]glycine prior to performing a bout of exercise. Immediately after exercise, isoenergetic mixed macronutrient beverages containing a variable amount of protein (0, 0.75, and 1.5g/100ml for CON, LP, and HP, respectively) according to fluid losses. Whole-body nitrogen turnover (Q), protein synthesis (S), protein breakdown (B), and protein balance (WBPB) were measured throughout exercise and the early acute recovery period (9h combined) as well as over 24h. Post-exercise protein intake from the beverage was ~0.18 and ~0.32g/kg body mass for LP and HP, respectively. Q, S, and B were significantly greater (main effect time, all P<0.001) over 9h as compared to 24h with no differences between conditions. WBPB was also greater over 9h as compared to 24h in all conditions (main effect time, P<0.001). Over 9h, WBPB was greater in HP (P<0.05) than LP and CON with a trend (P=0.075) towards LP being greater than CON. WBPB was positive over 9h for all conditions but only over 24h for HP. Post-exercise protein ingestion acutely increases net protein balance in healthy children early in recovery in a dose-dependent manner with larger protein intakes (~0.32g/kg) required to sustain a net anabolic environment over an entire 24h period.
    Journal of Applied Physiology 10/2014;
  • Journal of Applied Physiology 09/2014;
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    ABSTRACT: Aerobic exercise has been recognized as a stimulator of the immune system, but its effect on bacterial infection has not been extensively evaluated. We studied whether moderate aerobic exercise training prior to S. pneumoniae infection influences pulmonary inflammatory responses. BALB/c mice were divided into 4 groups: Sedentary Untreated (sedentary without infection); Sedentary Infected (sedentary with infection); Trained Untreated (aerobic training without infection); Trained Infected (aerobic training with infection). Animals underwent aerobic training for 4 weeks, and 72 h after last exercise training, animals received a challenge with S. pneumoniae and were evaluated either 12 h or 10 days after instillation. In acute phase, Sedentary Infected group had an increase in respiratory system resistance and elastance; number of neutrophils, lymphocytes and macrophages in bronchoalveolar lavage fluid (BAL); polymorphonuclear cells in lung parenchyma; and levels of KC, TNF- and IL-1ß in lung homogenates. Exercise training significantly attenuated the increase in all of these parameters and induced an increase in expression of antioxidant enzymes (CuZnSOD and MnSOD) in lungs. Trained Infected mice had a significant decrease in the number of colony-forming units of pneumococci in the lungs compared do Sedentary Infected animals. Ten days after infeccion, Trained Infected group exhibited lower numbers of macrophages in BAL, polymorphonuclear cells in lung parenchyma and IL-6 in lung homogenates compared with Sedentary Infected group. Our results suggest a protective effect of moderate exercise training against respiratory infection with S. pneumoniae. This effect is most likely secondary to an effect of exercise on oxidant-antioxidant balance.
    Journal of Applied Physiology 09/2014;
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    ABSTRACT: Although xenon is classically taught to be a "perfusion-limited" gas, (129)Xe in its hyperpolarized (HP) form, when detected by magnetic resonance, can probe diffusion-limitation. Inhaled HP (129)Xe diffuses across the pulmonary blood-gas barrier, and, depending on its tissue environment, shifts its resonant frequency relative to the gas-phase reference (0 ppm) by 198 ppm in tissue/plasma barrier and 217 ppm in red blood cells (RBCs). In this work, we hypothesized that in patients with idiopathic pulmonary fibrosis (IPF), the ratio of (129)Xe spectroscopic signal in the RBCs vs. barrier would diminish as diffusion-limitation delayed replenishment of (129)Xe magnetization in RBCs. To test this hypothesis, (129)Xe spectra were acquired in 6 IPF subjects as well as 11 healthy volunteers to establish a normal range. The RBC:barrier ratio was 0.55 ± 0.13 in healthy volunteers, but was 3.3-fold lower in IPF subjects (0.16 ± 0.03, p = 0.0002). This was caused by a 52% reduction in the RBC signal (p = 0.02) and a 58% increase in the barrier signal (p = 0.01). Furthermore, the RBC:barrier ratio strongly correlated with DLCO (r = 0.89, p < 0.0001). It exhibited a moderate inter-scan variability (8.25%), and in healthy volunteers it decreased with greater lung inflation (r = -0.78, p = 0.005). This spectroscopic technique provides a non-invasive, global probe of diffusion-limitation and gas-transfer impairment and forms the basis for developing 3D MR imaging of gas-exchange.
    Journal of Applied Physiology 07/2014;
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    ABSTRACT: Recently, an ultrasound-based elastography technique has been used to measure stiffness (shear modulus) of an active human muscle along the axis of contraction. Using this technique, we explored 1) whether muscle shear modulus, like muscle force, is length dependent; and 2) whether the length dependence of muscle shear modulus is consistent between electrically elicited and voluntary contractions. From nine healthy participants, ankle joint torque and shear modulus of the tibialis anterior muscle were measured at five different ankle joint angles during tetanic contractions and during maximal voluntary contractions. Fascicle length, pennation angle, and tendon moment arm length of the tetanized tibialis anterior calculated from ultrasound images were used to reveal the length-dependent changes in muscle force and shear modulus. Over the range of joint angles examined, both force and shear modulus of the tetanized muscle increased with increasing fascicle length. Regression analysis of normalized data revealed a significant linear relationship between force and shear modulus (R(2) = 0.52, n = 45, P < 0.001). Although the length dependence of shear modulus was consistent, irrespective of contraction mode, the slope of length-shear modulus relationship was steeper during maximal voluntary contractions than during tetanic contractions. These results provide novel evidence that length-force relationship, one of the most fundamental characteristics of muscle, can be inferred from in vivo imaging of shear modulus in the tibialis anterior muscle. Furthermore, the estimation of length-force relationship may be applicable to voluntary contractions in which neural and mechanical interactions of multiple muscles are involved.
    Journal of Applied Physiology 07/2014; 117(2):153-62.
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    ABSTRACT: To investigate the kinetics of cell-free DNA (cfDNA) due to exercise, we established a direct real-time PCR for the quantification of cfDNA from unpurified capillary plasma by amplification of a 90 bp and a 222 bp multi-locus L1PA2 sequence. 26 male athletes performed an incremental treadmill test. For cfDNA measurement capillary samples were collected serially from the fingertip pre, during and several times post exercise. Venous blood was drawn before and immediately after exercise to compare capillary and venous cfDNA values. To elucidate the strongest association of cfDNA accumulations with either cardiorespiratory or metabolic function during exercise, capillary cfDNA values were correlated with standard measures like heart rate, oxygen consumption or lactate concentrations. The venous cfDNA concentrations were significantly higher compared to the capillary plasma, but in both fractions cfDNA increased 9.8-fold and the values correlated significantly (r=0.796). During incremental treadmill running the capillary cfDNA concentrations increased nearly parallel to the lactate values. The values correlated best with heart rate and energy expenditure, followed by oxygen consumption, Borg values and lactate levels (0.710≤r≥0.808). With this article we present a sensitive procedure for the direct quantification of cfDNA in unpurified capillary plasma instead of purified venous plasma. Further studies should investigate the differences between capillary and venous cfDNA that might mirror different physiological mechanisms. Enhanced cardiorespiratory function during exercise might lead to the accumulation of cfDNA via the release of stress hormones that already increase at intensities below the anaerobic threshold. Furthermore, cfDNA might be released by neutrophil extracellular traps (NETs).
    Journal of Applied Physiology 05/2014;
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    ABSTRACT: Inspiratory resistance (RINSP) and reactance (XINSP) were measured for 7min at 5 Hz in 10 mild asymptomatic asthmatics and 9 healthy subjects to assess the effects of airway smooth muscle (ASM) activation by methacholine (MCh) and unloading by chest wall strapping (CWS) on the variability of lung function and the effects of deep inspiration (DI). Subjects were studied at control conditions, after MCh, with CWS, and after MCh with CWS. In all experimental conditions XINSP was significantly more negative in asthmatic than healthy subjects, suggesting greater inhomogeneity in the former. However, the variability of both RINSP and XINSP was increased by either ASM activation or CWS, without significant difference between groups. DI significantly reversed MCh-induced changes in RINSP in both asthmatic and healthy subjects but XINSP in the former only. This effect was impaired by CWS more in the asthmatic than healthy subjects. The velocity of RINSP and XINSP recovery after deep inspiration was faster in asthmatic than healthy subjects. In conclusion, these results support the opinion that the short-term variability of respiratory impedance is related to ASM tone or operating length, rather than the disease. Nevertheless, asthmatic ASM differs from the healthy one for an increased velocity of shortening and a reduced sensitivity to mechanical stress when strain is reduced.
    Journal of Applied Physiology 06/2013;
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    ABSTRACT: Dear Editor: Mündel et al. (1) reported an interesting study, which is done to investigate the mechanisms of action of nasal high flow oxygen (HNF) in spontaneously breathing healthy subjects, during wakefulness and sleep. It is widely believed that the application of high flow of heated and humidified oxygen to the nasopharynx forms a continuous positive airway pressure (CPAP), which can relieve respiratory distress (2). To investigate this theory the authors took a multi step approach first by measuring ventilation characteristics of 10 subjects at the awake state with 3 different flows (15, 30 and 45 L/min respectively) in a cross over fashion. Then the measurements were repeated while the subjects were sleeping. In this study, ventilation was monitored non-invasively by respiratory inductance plethysmographyIn another part of this study an artificial nose model was used to measure the effect of two different sizes of nasal high flow cannulas on flow characteristics and pressure/flow relationships during inspiration and expiration. One interesting finding is that, during wakefulness the tidal volume increased and respiratory rate decreased significantly with increasing flows. The decrease in respiratory rate was mainly due to an increase in expiratory time. This may be an indicator of increased expiratory resistance due to high flows in the opposite direction of expiratory flow. During sleep the measurements generated different results, in this setting increasing flow rates were associated with a decrease in minute ventilation due to a decrease in tidal volume with unchanged respiratory rate. In this study the authors did not measure the PaCO2 levels, perhaps HNF decreased minute ventilation by the washout of dead space of upper airways. This had been showed in a very recent study by Braunlich et al. in healthy subjects and pulmonary fibrosis patients (3). With the nasal cavity model, HNF increased expiratory resistance causing a slight positive pressure in the nasal cavity during expiration, but it decreased resistance during inspiration. The nasal prongs of the system contributed to the increased expiratory resistance by narrowing the nasal orifices (1).The findings of this study support the hypothesis that, HNF works by increasing expiratory pressure. But it was found to be different form the application of CPAP in nose model. The nose model can be criticized as it does not take the state of mouth (open or closed) in to account. Application of nasal CPAP in a normal subject would behave differently, especially if the mouth is open (2). There may be other mechanisms acting on the respiratory system during HNF, which may explain the findings during sleep, as the authors stated, the wash out of pharyngeal dead space with high flow, the lowering of metabolic needs to heat and humidify the inspiratory gases with heated humidified flow may play a role in sleeping subjects. Although there are several mechanisms proposed for the mechanism of favorable actions of HNF, the main action seems to be the increased airway pressures especially during expiration. In this way it works similar to the nasal CPAP, but the latter forms higher pressures in the upper airways as shown by Braunlich et al. study (3). 1 Mündel T, Feng S, Tatkov S, et al. Mechanisms of nasal high flow on ventilation during wakefulness and sleep. J Appl Physiol 114:1058-1065, 2013 2 Groves N, Tobin A. High flow nasal oxygen generates positive airway pressure in adult volunteers. Aust Crit Care 20:126-131, 2007 3 Bräunlich J, Beyer D, Mai D, et al. Effects of Nasal High Flow on Ventilation in Volunteers, COPD and Idiopathic Pulmonary Fibrosis Patients. Respiration 85:319-325, 2013
    Journal of Applied Physiology 05/2013; 05/2013.
  • Journal of Applied Physiology 01/2013;
  • Journal of Applied Physiology 12/2012;
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    ABSTRACT: In this paper we report the results of an experiment to investigate the emergence of ocular vestibular evoked myogenic potentials (OVEMPs) during the linear vestibular ocular reflex (LVOR) evoked by whole-body vibration (WBV). OVEMP and electrooculogram (EOG) montages were employed to record periocular potentials (POPs) from six subjects during WBV in the nasooccipital (NO) axis over a range of frequencies from 0.5 to 64 Hz with approximately constant peak head acceleration of 1.0 ms(-2) (i.e., 0.1 g). Measurements were made in two context conditions: a fixation context to examine the effect of gaze eccentricity (0 vs. 20°), and a visual context, where a target was either head-fixed or earth-fixed. The principal results are that from 0.5 to 2 Hz POP magnitude in the earth-fixed condition is related to head displacement, so with constant acceleration at all frequencies it reduces with increasing frequency, but at frequencies greater than 2 Hz both POP magnitude and POP gain, defined as the ratio of POP magnitude at 20 and 0°, increase with increasing frequency. By exhibiting this high-pass characteristic, a property shared with the LVOR, the results are consistent with the hypothesis that the OVEMP, as commonly employed in the clinical setting, is a high-frequency manifestation of the LVOR. However, we also observed low-frequency acceleration following POPs in head-fixed conditions, consistent with a low-frequency OVEMP, and found evidence of a high-frequency visual context effect, which is also consistent with the OVEMP being a manifestation of the LVOR.
    Journal of Applied Physiology 01/2012; 113(10):1613-1623.