J. Appl. Physiol. [JOURNAL]
Sun
200 papers
Footwear and illumination modulate muscle cocontraction strategies and joint work redistribution during stair-to-ground transition.
Xu Y, Zhu C, Sun D … +9 more , Jian X, Xia Z, Qian Y, Shen L, Song Y, Cen X, Sárosi J, Bíró I, Gu Y
J Appl Physiol (1985) · 2026 Apr · PMID 41770532 · Publisher ↗
Reduced illumination diminishes visual input, while footwear cushioning alters impact absorption. How these factors affect joint loading and muscle activation during the stair-to-ground transition remains unclear. This s...
Reduced illumination diminishes visual input, while footwear cushioning alters impact absorption. How these factors affect joint loading and muscle activation during the stair-to-ground transition remains unclear. This study investigated the effects of illumination and footwear on joint kinetics and muscle coordination during the transition step of stair descent, elucidating regulatory mechanisms and potential interactions. Twenty-four healthy adults performed a stair-to-level transition under four conditions (illumination: bright vs. dim; footwear: shoed vs. barefoot). Kinematic trajectories, ground reaction forces, and electromyographic signals were recorded for the dominant side during the transition step's stance phase. Analysis used two-way repeated-measures ANOVA and one-dimensional statistical parametric mapping. Illumination effects primarily manifested as increased hip flexion-extension negative work in bright conditions, whereas dim conditions decreased knee abduction moments and adduction-abduction negative work. The shoed condition increased ground reaction force loading rates and joint moments across multiple degrees of freedom at the hip, knee, and ankle, significantly elevating knee flexion-extension and hip rotational positive work. Conversely, the barefoot condition showed higher midstance ground reaction forces, greater ankle plantarflexion moments, increased hip rotational negative work, and higher knee and ankle muscle coactivation indices. Compared with illumination, footwear exerts a more pronounced effect on lower limb joint moments, negative work, and muscle activation during the stair descent transition phase. These findings provide directions for future research on footwear-ground interaction properties and lower limb motor control. This study reveals that footwear impacts lower limb biomechanics more significantly than illumination during the stair-to-ground transition. Although dim light alters knee stability and hip work, footwear cushioning fundamentally redistributes joint moments and negative work. Notably, barefoot conditions trigger higher muscle coactivation and ankle loading to manage impact. These findings highlight how environmental and equipment factors interact, offering critical insights for improving footwear design and motor control strategies during high-risk locomotor transitions.
Jugular venous flow dynamics during acute weightlessness and partial gravity in parabolic flight.
Lytle JR, Miller AE, Martin DS … +5 more , Miller CA, Young M, Laurie SS, Macias BR, Lee SMC
J Appl Physiol (1985) · 2026 Apr · PMID 41770529 · Publisher ↗
Weightlessness (0.00-G) and partial gravity exposures may contribute to internal jugular vein (IJV) distension and altered cerebral hemodynamics, which may increase the risk of venous thrombosis. Nine participants were s...
Weightlessness (0.00-G) and partial gravity exposures may contribute to internal jugular vein (IJV) distension and altered cerebral hemodynamics, which may increase the risk of venous thrombosis. Nine participants were studied while in supine and seated position in normal gravity and during parabolic flight while seated. Participants were exposed to 10 parabolas at each G-level: 0.00-G, 0.25-G, 0.50-G, and 0.75-G. Bilateral IJV cross-sectional area (CSA), pressure, and flow were assessed using two-dimensional (2-D) and Doppler ultrasound. Compared with seated preflight, left IJV CSA increased during 0.00-G, 0.25G-, and 0.50-G, and right IJV CSA increased during 0.00-G and 0.25-G exposures ( < 0.05). IJV CSA was not significantly different between preflight supine and seated position 0.00-G. Left IJV pressure during all reduced G-levels and right IJV pressure during 0.00- and 0.50-G were significantly greater than preflight seated. Normal forward flow was observed in the right and left IJV in all participants preflight and in the right IJV during all G-levels. In seven of nine participants, the left IJV presented with normal flow across partial-G levels and weightlessness. Stagnant flow was observed in the left IJV during 0.00-G in two participants and during 0.25- and 0.50-G in one participant. Together these data reveal a graded effect in the left and right IJV CSA and pressure across increasing G-levels and normal forward flow in most individuals. Venous stasis developed in the left IJV during acute reduced gravity exposures in two participants, suggesting that astronauts should be monitored for flow abnormalities early in their mission and while on the Moon and Mars. Weightlessness-induced blood flow stasis in internal jugular veins (IJV) may contribute to an increased risk of thrombosis during spaceflight. Here we report that reduced gravity leads to IJV distension in healthy participants and that 0.00-G, 0.25-G, and 0.50-G exposures resulted in stagnant blood flow in the left IJV in one participant. Reduced gravity on the Moon and Mars may be insufficient to protect against venous flow abnormalities.
Mea culpa: so how does HERstory look in my HIStory?
Hagberg JM
J Appl Physiol (1985) · 2026 Apr · PMID 41770525 · Publisher ↗
The underrepresentation of female individuals as research participants and manuscript authors is a longstanding issue in science in general and in the discipline of applied and exercise physiology. Over my ∼50 yr as an i...
The underrepresentation of female individuals as research participants and manuscript authors is a longstanding issue in science in general and in the discipline of applied and exercise physiology. Over my ∼50 yr as an investigator, mentor, author, manuscript reviewer, and journal editor, my decisions obviously impacted these trends. To determine whether I was part of the problem or the solution, I audited my entire publication history and compared the results to a 50% aspirational census-based goal and to the composite across the histories of three leading exercise/applied physiology journals. A total of 10,706 individuals were included in my 203 human studies-49.8% were female individuals versus 42.5% female research participants for the other three journals. Forty percent of my studies had female research participants, which is above the composite 35% for the other journals. Of my single sex studies, 23% included female participants, which is above the 15% for the three journals. The authors on my articles are 16% female individuals, which is below the composite 23% for the other journals. Thus, except for the inclusion of female research participants in my studies, I have contributed to the ongoing problem and not the solution to the underrepresentation of female individuals in the discipline of exercise/applied physiology. It remains for each of us to do some introspective thinking relative to this ongoing issue because the decisions to rectify this situation have to come from individuals who choose to address this issue directly in their research programs. Female individuals are underrepresented as participants and authors in applied/exercise physiology studies. Over my 50 yr in the field, my decisions obviously impacted these trends. Reviewing my entire publication history, except for including female research participants, I have contributed to this problem over the course of my career. It remains for each of us to look inside ourselves to determine whether we want to be part of the solution or part of the problem.
Effects of controlled carbon dioxide delivery by a novel device on sleep in healthy subjects.
Liang SF, He BT, Wellman A … +7 more , Chen YY, Wang Y, Deng XB, Vakulin A, Steier J, Schwartz AR, Luo YM
J Appl Physiol (1985) · 2026 Mar · PMID 41758059 · Publisher ↗
Low-dose carbon dioxide (CO) can stabilize ventilatory drive, reduce sleep-disordered breathing, and improve sleep quality. However, the existing delivery systems introduce dead space and resistance that limit tolerabili...
Low-dose carbon dioxide (CO) can stabilize ventilatory drive, reduce sleep-disordered breathing, and improve sleep quality. However, the existing delivery systems introduce dead space and resistance that limit tolerability. We developed a novel mask with low resistance and minimal dead space to deliver CO and evaluated its overnight effects on neural respiratory drive, sleep architecture, and potential CO accumulation in healthy individuals. Sixteen healthy volunteers [age 42 ± 15 yr; body mass index (BMI) 22.0 ± 2.3 kg/m] first underwent polysomnography with diaphragmatic electromyography (EMG) recorded via esophageal electrodes under inhalation of different concentrations of CO. Participants then completed four consecutive overnight polysomnography sessions, with each night involving inhalation of a different CO concentration (0.0%, 2.5%, 3.5%, or 5.0%) in randomized order. Arterial blood gases were sampled in the evening before inhalation and the following morning during CO exposure. Overnight urinary catecholamines were also measured. Neural respiratory drive increased dose-dependently. Sleep efficiency was highest at 2.5% CO (91.7 ± 5.7%) and lowest at 5.0% (78.5 ± 10.1%, < 0.001); 3.5% CO showed sleep efficiency similar to room air, whereas 5.0% reduced rapid eye movement (REM) sleep and increased arousals. Blood gases, blood pressure, heart rate, and catecholamines remained normal at ≤3.5%. Baseline blood gases remained normal after multiple consecutive nights of CO inhalation. Overnight inhalation of 2.5% CO delivered via the special mask enhances sleep efficiency without adverse physiological effects. Concentrations ≤3.5% appear safe, and no cumulative effect was observed after multiple consecutive nights of CO inhalation in healthy subjects. A novel low-resistance open-mask system enables safe delivery of low-dose CO during sleep. Inhaling 2.5% CO improves sleep efficiency and increases N3 sleep in healthy adults, without CO retention or physiological stress. CO up to 3.5% was safe and well tolerated and showed no cumulative effects. These findings demonstrate the physiological safety of low-dose CO during sleep and support its potential for treating hypocapnia-related central sleep apnea.
Local apocynin improves acetylcholine- but not insulin-mediated vasodilation in the cutaneous microvasculature of women with a history of gestational diabetes.
Maurer GS, O'Neill BT, Jalal DI … +1 more , Stanhewicz AE
J Appl Physiol (1985) · 2026 Apr · PMID 41758055 · Full text
Women with a history of gestational diabetes mellitus (GDM) are at a significantly greater risk of developing cardiovascular disease and type 2 diabetes compared with healthy control (HC) women who had an uncomplicated p...
Women with a history of gestational diabetes mellitus (GDM) are at a significantly greater risk of developing cardiovascular disease and type 2 diabetes compared with healthy control (HC) women who had an uncomplicated pregnancy. Microvascular endothelial dysfunction, mediated in part by elevated oxidative stress, persists after pregnancy complicated by GDM. We examined whether locally reducing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived oxidative stress using apocynin would improve acetylcholine- and insulin-mediated vasodilation in the cutaneous microvasculature of women with a history of GDM. We evaluated in vivo microvascular endothelium-dependent vasodilator function by assessing cutaneous vascular conductance responses to graded infusions of acetylcholine (10-10 M) and insulin (10-10 M) in women with a history of GDM and HC women in control sites (Lactated Ringer's), sites treated with 15 mM l-NAME (-nitro-l-arginine methyl ester; nitric oxide synthase inhibitor), 100 µM apocynin (NADPH oxidase inhibitor), and 15 mM l-NAME combined with 100 µM apocynin. Women with a history of GDM had reduced acetylcholine- ( = 0.002) and insulin- ( = 0.006) mediated dilation responses compared with HC women. Local NADPH oxidase inhibition with apocynin improved acetylcholine-mediated ( = 0.003) but not insulin-mediated ( = 0.169) dilation in women with a history of GDM. Attenuations in microvascular vasodilation responses to acetylcholine are mediated, in part, by NADPH oxidase-derived oxidative stress. Our findings suggest that NADPH oxidase may be a viable therapeutic target to reduce future disease risk in women with a history of GDM. Women who experienced gestational diabetes are at a high risk of developing cardiovascular disease and type 2 diabetes. This risk may be mediated, in part, by endothelial dysfunction after pregnancy. We demonstrate that NADPH oxidase inhibition with apocynin improves microvascular endothelial responses to acetylcholine but not to insulin in healthy women with a history of gestational diabetes. These findings suggest that NADPH oxidase contributes to microvascular endothelial dysfunction and chronic disease progression after gestational diabetes.
Correction for Dial et al., volume 136, 2024, p. 996-1006.
J Appl Physiol (1985) · 2026 Mar · PMID 41733534 · Full text
Abstract loading — click title to view on PubMed.
Safe cold-water thresholds while wearing wetsuits approved for open water swimming competitions.
Skutnik BC, Owen MG, Hite MJ … +6 more , Sweitzer L, Petersen JW, Johnson BD, Mickleborough TD, Stager JM, Schlader ZJ
J Appl Physiol (1985) · 2026 Mar · PMID 41730325 · Publisher ↗
This study tested the hypothesis that the critical cold-water temperature (T) at which core temperature can no longer be maintained while wearing an approved wetsuit is below the currently mandated water temperature of 1...
This study tested the hypothesis that the critical cold-water temperature (T) at which core temperature can no longer be maintained while wearing an approved wetsuit is below the currently mandated water temperature of 16°C. We further aimed to examine the effect of wetsuit sleeves on T. We recruited 20 trained swimmers (12 men, 8 women) who completed 120-min progressive cooling swim trials in a swim flume. Water temperature at the start was 16°C and decreased ∼0.15°C every 10 min while swimming at race-representative intensity and wearing a full-length wetsuit. A subset ( = 8) completed an additional swim trial comparing sleeved versus sleeveless wetsuits. The water temperature upon which core temperature could not be maintained (i.e., T) was identified using segmental linear regression. Median T was 15.0°C [95% confidence interval (CI): 14.8-15.3°C], significantly below the 16°C regulation ( < 0.001). No differences in T were observed between genders [ = 0.78; men: 15.0°C (95% CI: 14.6-15.3°C); women: 14.91°C (95% CI: 14.6-15.4°C)] or wetsuit types ( = 0.90; sleeved: 15.1 ± 0.5°C; sleeveless: 15.1 ± 0.6°C). Multiple regression analysis revealed that body fat percentage (β-coefficient: -0.06088: = 0.0390), metabolic heat production (β-coefficient: -0.004416; = 0.0079), and body surface area-to-mass ratio (β-coefficient: -370.6; = 0.0078) significantly explained T ( = 0.41, = 0.008). Although our data demonstrate that trained swimmers can physiologically tolerate temperatures below current regulations, we recommend maintaining the 16°C mandate to provide appropriate safety margins for the diverse competitive population and variable real-world conditions encountered in open water swimming competitions. Using a novel experimental protocol, this study provides empirical determination of critical cold-water temperature for competitive open water swimmers while wearing two different World Aquatics-approved wetsuits designs. Well-trained swimmers protected core temperature down to 15.0°C, below current 16°C regulations, which did not differ between sleeved and sleeveless wetsuits. These findings provide objective evidence supporting current conservative regulatory approaches.
Real-time visual feedback affects peak propulsive horizontal force and metabolic cost in individuals with unilateral transtibial amputation during walking.
Hirschman CE, Zhang-Lea JH, Grabowski AM
J Appl Physiol (1985) · 2026 Apr · PMID 41730306 · Publisher ↗
Individuals with unilateral transtibial amputation (uTTA) using a passive-elastic energy storage and return (ESAR) prosthesis to walk have asymmetrical peak propulsive horizontal ground reaction force (hGRF) compared wit...
Individuals with unilateral transtibial amputation (uTTA) using a passive-elastic energy storage and return (ESAR) prosthesis to walk have asymmetrical peak propulsive horizontal ground reaction force (hGRF) compared with nonamputees. Investigating and normalizing peak propulsive hGRF could be beneficial for individuals with uTTA, who experience a greater metabolic cost of walking and greater risk of developing secondary comorbidities compared with nonamputees. Use of the BiOM stance-phase battery-powered prosthesis can decrease peak propulsive hGRF asymmetry and the metabolic cost of walking compared with an ESAR prosthesis in people with uTTA. Moreover, providing individuals with uTTA feedback of peak propulsive hGRF could change peak propulsive hGRF and metabolic cost. Twelve participants with uTTA walked at 1.25 m/s while using an ESAR and BiOM prosthesis and were provided with visual feedback of peak propulsive hGRF. We found that when participants used the BiOM, affected leg (AL) peak propulsive hGRF increased by 0.014-0.017 body weight (BW), peak propulsive hGRF asymmetry decreased by 9.4-16.3 percentage points, and net metabolic power decreased by 0.16-0.26 W/kg compared with when they used an ESAR prosthesis. When participants were given visual feedback of peak propulsive hGRF, they increased AL peak propulsive hGRF and decreased peak propulsive hGRF asymmetry but incurred a greater metabolic cost when using either prosthesis. Our results suggest that future device designs should explore providing feedback of biomechanical variables and device control to the user during walking so that individuals with uTTA can more effectively use a powered prosthesis. Individuals with unilateral transtibial amputation walked while using an energy storage and return prosthesis and the BiOM prosthesis and were provided with visual feedback of peak propulsive horizontal force (hGRF). Visual feedback increased affected leg peak propulsive hGRF and decreased peak propulsive hGRF asymmetry, but participants incurred a greater metabolic cost when using either prosthesis. Future device designs should explore biofeedback and device control to help individuals more effectively use a powered prosthesis.
Noninvasive quantification of energy transfer during mechanical ventilation.
Gutierrez G
J Appl Physiol (1985) · 2026 Apr · PMID 41730301 · Publisher ↗
Ventilator-to-patient energy transfer during insufflation (ET) is increasingly recognized as a potential contributor to ventilator-induced lung injury. Current formulations of ET, however, neglect patient-generated respi...
Ventilator-to-patient energy transfer during insufflation (ET) is increasingly recognized as a potential contributor to ventilator-induced lung injury. Current formulations of ET, however, neglect patient-generated respiratory muscle effort (P), a potentially important modifier of ventilator energy delivery. Accordingly, the aim of this study was to develop and validate mathematical expressions that quantify breath-by-breath ETv in the presence of respiratory effort using only airway pressure (P) and flow (F) signals. Equations were derived from the single-compartment model of the respiratory system relating the pressure-time product of respiratory muscle pressure (PPTP) to ET during volume-controlled (VCV) and pressure-controlled ventilation (PCV). Model validation was performed using previously acquired high-fidelity P and F recordings from two separate cohorts of invasively ventilated patients receiving VCV or PCV. Calculated ET values were compared with those measured by trapezoidal integration of inspiratory pressure-volume loops. There was excellent agreement between calculated and measured ETv in both modes of ventilation (VCV: = 0.99; bias 0.3 ± 0.9 J·min; PCV: = 0.98; bias -0.10 ± 1.94 J·min). These results demonstrate that ventilator-to-patient energy transfer during controlled mechanical ventilation can be quantified accurately and noninvasively on a breath-by-breath basis using airway signals alone. The developed model also provides a physiological basis for real-time assessment of insufflation energy dynamics. This study presents and validates a noninvasive method that uses only airway pressure and flow signals to dynamically quantify energy transfer to mechanically ventilated patients while accounting for respiratory effort. Equations derived from a classic one-compartment model accurately predicted individual breath energy transfer during volume- and pressure-controlled ventilation. The method provides a physiological framework to explore, in real-time and non invasively, the dynamics and clinical significance of ventilator-to-patient energy transfer.
Moderate hyperthermia impairs dynamic cerebral autoregulation but not its directional sensitivity.
Taghizadeh M, Roy MA, Soleimani Dehnavi S … +2 more , Gagnon D, Brassard P
J Appl Physiol (1985) · 2026 Apr · PMID 41712306 · Publisher ↗
Dynamic cerebral autoregulation (dCA) maintains cerebral blood flow (CBF) relatively constant during rapid fluctuations in mean arterial pressure (MAP). This autoregulation exhibits directional sensitivity, characterized...
Dynamic cerebral autoregulation (dCA) maintains cerebral blood flow (CBF) relatively constant during rapid fluctuations in mean arterial pressure (MAP). This autoregulation exhibits directional sensitivity, characterized by greater buffering capacity of CBF changes when MAP increases than when MAP decreases. Whole body hyperthermia may alter autoregulatory function through physiological adjustments that elevate cerebrovascular resistance and reduce CBF. We hypothesized that moderate hyperthermia (+1°C core temperature) improves dCA without affecting its directional sensitivity. Twenty healthy young adults (9 males) underwent oscillatory lower body negative pressure (OLBNP, 0 to -90 Torr) at 0.05 Hz and 0.10 Hz under normothermic and hyperthermic conditions. Middle cerebral artery mean blood velocity (MCAvmean) and MAP were continuously recorded. A multimetric approach was applied to quantify dCA using transfer function analysis (TFA) and directional sensitivity analysis [time-adjusted changes in MCAvmean per alterations to MAP in absolute (ΔMCAvmean/ΔMAP) and relative (%MCAvmean/%MAP) terms]. Hyperthermia increased TFA coherence and reduced TFA phase at both frequencies, while TFA gain and normalized gain were elevated at 0.10-Hz OLBNP (all < 0.05), indicating impaired dCA. Directional sensitivity, defined by higher ΔMCAvmean/ΔMAP during MAP decreases than increases, was observed only at 0.10 Hz ( < 0.0001), whereas %MCAvmean/%MAP revealed this pattern at both frequencies (all < 0.05) without thermal effects (all > 0.05). These novel findings demonstrate that moderate poikilocapnic hyperthermia attenuates the dynamic buffering capacity of the cerebrovasculature, particularly at higher frequencies, while preserving the inherent directional sensitivity of the cerebral pressure-flow relationship. These findings suggest that distinct regulatory mechanisms may underlie the dynamic and directional components of cerebral autoregulation. Using a multimetric approach combining transfer function analysis with absolute and normalized directional sensitivity metrics, we show that moderate hyperthermia impairs dynamic cerebral autoregulation while preserving its directional sensitivity. Notably, asymmetry in the cerebral pressure-flow relationship was evident at both 0.05 and 0.10 Hz when using the normalized metric, despite heat-induced reductions in dynamic buffering. These findings suggest that distinct mechanisms govern the dynamic and directional components of cerebral autoregulation.
Sex-related differences in submaximal but not maximal motor unit firing rates of the human vastus intermedius and vastus lateralis.
Fanous J, Zero AM, Rice CL
J Appl Physiol (1985) · 2026 Mar · PMID 41712270 · Publisher ↗
Sex-related differences in motor unit (MU) behavior are sparse, particularly across a full range of contraction intensities, and contradictory, with various mechanisms proposed to address potential differences. Thus, the...
Sex-related differences in motor unit (MU) behavior are sparse, particularly across a full range of contraction intensities, and contradictory, with various mechanisms proposed to address potential differences. Thus, the purpose was to investigate MU firing rates and electrically evoked contractile properties of the quadriceps femoris in males and females across the full force range. In 16 participants (8 females:8 males), ultrasound-guided intramuscular tungsten microelectrodes were used to record MU firing rates from the vastus intermedius and lateralis during isometric knee extension contractions upward to maximum. Electrically evoked twitch and doublet responses assessed the contractile properties of the quadriceps. Strength in females was ∼60% of that in males ( < 0.001), with ∼95% voluntary activation during maximal contractions in both groups. A total of 4,122 MU trains were analyzed (balanced sample across sex). Grouped firing rates in females were 1.6 to 2.8 Hz higher ( < 0.001) at the submaximal intensities, with no difference in MU firing rates at maximal voluntary contraction (MVC) ( = 0.694). No difference in twitch or doublet parameters of contractile speed was found ( > 0.05). These differences in mean firing rates may have functional implications, particularly at submaximal intensities in which small alterations in firing rate induce large changes in force. Force modulation through rate coding during submaximal contractions is different between males and females in these two muscles of the quadriceps. However, maximal rates were not different and thus the absolute rate-coding capacity of both sexes is the same. The difference at submaximal contractions may be due to intrinsic motor neuron excitability rather than intrinsic muscle contractile speed. This study compares motor-unit (MU) firing rates between males and females in the quadriceps across a full force range. Our findings reveal no difference in maximal firing rates between sexes, but at submaximal intensities MU firings in females were modestly faster; with no difference in normalized muscle contractile properties. Overall force gradation strategies during voluntary contractions are different in females, perhaps related to sex-based differences in intrinsic motoneuron properties rather than musculoskeletal parameters.
Norepinephrine stress reactivity links to a lipid-rich coronary fat phenotype in humans: a cross-sectional study.
von Känel R, Albertini T, Holzgang SA … +6 more , Princip M, Giannopoulos AA, Buechel RR, Sivakumar S, Zuccarella-Hackl C, Pazhenkottil AP
J Appl Physiol (1985) · 2026 Mar · PMID 41697119 · Publisher ↗
Pericoronary adipose tissue (PCAT) attenuation from coronary computed tomography angiography (CCTA) is an imaging biomarker of coronary inflammation. Experimental evidence suggests that sympathetic activation and norepin...
Pericoronary adipose tissue (PCAT) attenuation from coronary computed tomography angiography (CCTA) is an imaging biomarker of coronary inflammation. Experimental evidence suggests that sympathetic activation and norepinephrine (NE) can alter perivascular adipose tissue (PVAT) composition. Whether NE stress reactivity relates to PVAT phenotype, as reflected by PCAT attenuation, or varies by chronic stress exposure is unclear. We studied 60 male physicians (30 with clinical burnout, 30 controls) without known cardiovascular disease. Participants underwent CCTA for PCAT assessment and Trier Social Stress Test to induce psychosocial stress. Plasma NE was measured at baseline, immediately, +15, +45, and +90 min poststress. Relative NE increase (immediately post stress minus baseline) was the primary NE index; absolute NE increase, NE area under the curve with respect to increase (AUC-I) and ground (AUC-G; total output) were secondary indices. Multivariable regression adjusted for burnout, age, waist circumference, low-density lipoprotein cholesterol, and segment stenosis score. Greater relative NE stress increase was independently associated with lower total PCAT attenuation (average across three coronary arteries; partial = 0.12, = 0.010). Each 10% relative NE increase corresponded to ∼1 HU lower attenuation. Similarly, an absolute NE increase of 50 pg/mL (partial = 0.08, = 0.036) and a 5,000-unit increase in NE AUC-I (partial = 0.07, = 0.049) corresponded to ∼1 HU lower attenuation, whereas NE AUC-G showed no association ( = 0.35). Acute sympathetic stress reactivity, reflected by NE increase, is associated with a lipid-rich PVAT phenotype, as indicated by lower PCAT attenuation, supporting PVAT responsiveness to adrenergic stimulation. Excess NE reactivity may represent a biomarker of early coronary vulnerability. This study highlights the association between acute norepinephrine (NE) stress reactivity and pericoronary adipose tissue (PCAT) attenuation, a marker of coronary inflammation. In male physicians, greater NE increase after acute psychosocial stress was linked to lower PCAT attenuation, reflecting a more lipid-rich perivascular adipose tissue phenotype. This suggests that heightened NE reactivity may indicate early coronary vulnerability. Burnout did not modify this relationship, pointing to NE reactivity as a distinct physiological pathway in cardiovascular risk.
Similar performance and muscle adaptations between intervals with and without blood flow restriction in well-trained cyclists.
Zambolin F, Vikmoen O, Cumming KT … +7 more , Skattebo Ø, Ødemark HN, Øfsteng SF, Hammarström D, Hansen J, Rønnestad BR, Raastad T
J Appl Physiol (1985) · 2026 Mar · PMID 41696846 · Publisher ↗
Blood flow restriction (BFR) allows exercise at a lower external load with similar or greater improvements compared with traditional training in nontrained individuals. However, the effect in well-trained competitive ath...
Blood flow restriction (BFR) allows exercise at a lower external load with similar or greater improvements compared with traditional training in nontrained individuals. However, the effect in well-trained competitive athletes is unclear. The aim of this study was to compare effort-matched high-intensity interval training (HIIT) microcycles performed with or without BFR on endurance performance and muscular adaptations in well-trained cyclists. Seventeen well-trained cyclists (31 ± 9 yr; V̇o: 67 ± 6 mL × kg × min) were randomized to groups performing five HIIT sessions (6 × 5 min intervals with 2.5 min of recovery) with (BFR) or without (HIIT) thigh cuffs occluding the legs. V̇o, power output at 4 mmoL/L blood lactate (LT4), mean power output during 5-min maximal cycling (MPO), percentage of V̇o used at LT4 (%V̇o@LT4), hemoglobin mass, and blood volume (BV) were assessed. Muscle biopsies from evaluated muscle cross-sectional area (CSA), capillaries, citrate synthase, hydroxyacyl-coenzyme A dehydrogenase, and cytochrome c oxidase subunit 4. The BFR group trained at a 42% lower power output than the HIIT group (177 ± 3 W vs. 307 ± 8 W, respectively, < 0.01), but with no differences in heart rate or rate of perceived exertion. Both groups improved MPO by ⁓4%, with no changes in LT4, V̇o, hemoglobin mass, and BV. HIIT showed a significant reduction in CSA for type 2 muscle fibers compared with BFR, whereas no changes were found in the other muscle analyses. BFR applied during a 6-day interval microcycle provides similar performance gains as traditional HIIT in well-trained cyclists. Blood flow restriction training (BFR) enables well-trained cyclists to perform high-intensity interval training (HIIT) at lower power outputs while still achieving comparable improvements in performance and muscle adaptations after a 6-day interval microcycle training. By matching effort rather than power output, this approach could help manage training load without compromising physiological gains. These findings suggest that BFR could be a tool in the training program of competitive athletes, especially during periods requiring reduced mechanical stress.
It is all in the genes. Wait ….
Kleinsasser AT, Burtscher M
J Appl Physiol (1985) · 2026 Feb · PMID 41686154 · Publisher ↗
Abstract loading — click title to view on PubMed.
Higher carotid artery backward pressure and load-dependent stiffness among women with a history of preeclampsia: association with cognitive functions.
Davis KG, Armstrong MK, Nuckols VR … +4 more , Pewowaruk R, Santillan DA, Santillan MK, Pierce GL
J Appl Physiol (1985) · 2026 Mar · PMID 41685981 · Publisher ↗
Women with a history of preeclampsia (hxPE) show reduced executive function (EF) and processing speed (PS) compared with a healthy pregnancy (HP). Central (carotid) artery pulsatile pressure hemodynamics and stiffness ar...
Women with a history of preeclampsia (hxPE) show reduced executive function (EF) and processing speed (PS) compared with a healthy pregnancy (HP). Central (carotid) artery pulsatile pressure hemodynamics and stiffness are associated with reduced cognitive function with aging, but it is unknown if this relation exists in women with a hxPE. We hypothesized that higher carotid artery pulsatile pressure hemodynamics and stiffness would mediate reductions in cognitive function among women with a hxPE. Carotid artery applanation tonometry, B-mode ultrasonography, and wave separation analysis were used in 121 postpartum women (9 mo-5 yr after delivery, aged 18-45 yr; = 59 hxPE and = 62 HP) to calculate forward and backward pressure wave amplitudes, and pulse pressure (PP). Carotid stiffness components were derived by participant-specific exponential modeling. EF and PS were represented as Z-scores. Mediation analysis determined the contribution of carotid outcomes in association between preeclampsia status and cognitive function. Women with a hxPE had higher carotid Pb, PP, and load-dependent stiffness compared with those with HP (body mass index and age adjusted, = 0.009, = 0.005, and < 0.001, respectively). After education and age adjustment, the hxPE group had significantly lower PS compared with HP ( = 0.009); executive function was not different ( = 0.08). No pulsatile pressure hemodynamic or stiffness factor mediated associations between preeclampsia status and PS (all > 0.05). Women with a hxPE have greater carotid PP, Pb, and load-dependent stiffness, compared with a HP. Neither carotid artery pulsatile pressure hemodynamics or load-dependent stiffness mediated lower PS among women with a hxPE. The novel finding is that higher carotid artery pulsatile pressure hemodynamics and load-dependent stiffness do not mediate reduced processing speed performance in young women with a history of preeclampsia. No difference was seen in EF between groups when adjusted for education and age. These findings clarify the contribution of pulsatile pressure hemodynamics to cardiovascular disease risk and highlight the need for future research on cognitive performance in women with a history of preeclampsia.
Neuromuscular fatigue induced by the combined application of neuromuscular electrical stimulation and muscle lengthening.
Pineau A, Martin A, Lepers R … +1 more , Papaiordanidou M
J Appl Physiol (1985) · 2026 Mar · PMID 41685704 · Publisher ↗
This study compared neuromuscular fatigue induced by an acute wide-pulse high-frequency session, either applied in an isometric condition (WPHF) or combined with muscle lengthening (WPHF + LEN). Fifteen participants comp...
This study compared neuromuscular fatigue induced by an acute wide-pulse high-frequency session, either applied in an isometric condition (WPHF) or combined with muscle lengthening (WPHF + LEN). Fifteen participants completed two randomized sessions, which involved 30 stimulation trains (pulse duration: 1 ms; frequency: 100 Hz; duty cycle: 15 s ON/15 s OFF) applied to the posterior tibial nerve at low stimulation intensity [5%-10% maximal voluntary contraction (MVC)]. In the WPHF session, the ankle joint was held at a reference angle (90°), whereas a 10° muscle lengthening was superimposed during the stimulation in the WPHF + LEN session. Before and after each session, MVC was measured along with neural [voluntary activation level (VAL)] and muscular [potentiated twitch (Pt)] changes. Torque-time integral (TTI) was recorded for each train, and the total TTI (∑TTI) was calculated. Results showed a comparable decrease in MVC torque after the two sessions (-7.8 ± 6.9% for WPHF and -9.4 ± 5.7% for WPHF + LEN, < 0.001) associated with a significant reduction in Pt amplitude ( < 0.001), indicating muscular changes, whereas VAL remained unchanged. ∑TTI was not different between sessions (9,600 Nm·s for WPHF; 9,550 Nm·s for WPHF + LEN; = 0.95). However, although TTI significantly decreased throughout the WPHF session, it was preserved during the WPHF + LEN session. These findings indicate a similar amount of neuromuscular fatigue after the two sessions, primarily attributed to muscular alterations. Nevertheless, the combination of WPHF stimulation with muscle lengthening appears advantageous for preserving torque production throughout the stimulation trains. Results of the present study indicate that a single session of WPHF stimulation modality either applied alone or with muscle lengthening induces the same level of neuromuscular fatigue. Despite no significant difference in total evoked torque between sessions, the present findings highlight potential advantages of superimposing muscle lengthening to preserve torque production during repeated WPHF trains.
Dynamic neurovascular adaptation of the retina during high-altitude hypoxia: integrated analysis of ERG and OCTA changes in healthy subjects.
Yu X, Li J, Wang Y … +2 more , Li X, Ding L
J Appl Physiol (1985) · 2026 Mar · PMID 41665522 · Publisher ↗
Acute hypobaric hypoxia induces rapid neurovascular adjustments in the central nervous system, yet the specific spatiotemporal dynamics of these responses remain incompletely understood. The retina, with its high metabol...
Acute hypobaric hypoxia induces rapid neurovascular adjustments in the central nervous system, yet the specific spatiotemporal dynamics of these responses remain incompletely understood. The retina, with its high metabolic demand and direct accessibility, provides a unique noninvasive model to investigate neurovascular coupling dynamics under simulated high-altitude hypoxia. Twenty-one healthy adults underwent ophthalmic evaluations at sea level, during a stepwise ascent to 4,500 m in a hypobaric chamber (simulated altitudes: 3,500 m, 4,000 m, 4,500 m), and during a subsequent recovery phase. Images were acquired 10 min after reaching each plateau. Optical coherence tomography angiography (OCTA) was used to quantify vessel density (VD), perfusion area (PA), and small-vessel density (SVD). Full-field electroretinogram (ERG) was recorded under dark- and light-adapted conditions. Linear mixed-effects models and correlation analyses were used to assess altitude-related changes. The superficial vascular plexus (SVP) exhibited a sustained compensatory vasodilation (increased VD and PA) across all altitudes. In contrast, ERG amplitudes declined significantly at 4,500 m, revealing a functional supply-demand mismatch. Strict statistical analysis revealed a loss of linear neurovascular correlation during hypoxia, while strong correlations re-emerged during the recovery-phase. In addition, physiological parameters did not immediately return to baseline during recovery, indicating a distinct physiological hysteresis. The retina displays differential neurovascular responses during progressive hypoxia. Although the superficial microvasculature mounts a sustained compensatory response, neuronal function decompensates under severe stress. These results suggest that retinal vascular dilation reaches a functional ceiling, leading to neurovascular uncoupling, and that the system exhibits a metabolic lag during recovery. This study identifies a critical "functional mismatch" in retinal neurovascular adaptation to acute hypoxia. We demonstrate that while superficial microvasculature sustains compensatory dilation up to simulated 4,500 m, neuronal function significantly declines. This dissociation suggests that vascular autoregulation reaches a functional ceiling, failing to sustain neural activity under severe stress. These findings establish the retina as a sensitive noninvasive model for determining the physiological limits of cerebral oxygen regulation.
Acute effects of inhaled nitric oxide on inspiratory neural drive, dyspnea, and exercise endurance in symptomatic patients post-pulmonary embolism.
Phillips DB, James MD, Vincent SG … +11 more , Smyth RM, Chau B, Darko CA, Milne KM, Collins SÉ, D'Arsigny CL, de-Torres JP, de Wit K, Johri A, Neder JA, O'Donnell DE
J Appl Physiol (1985) · 2026 Apr · PMID 41665425 · Publisher ↗
Following pulmonary embolism (PE), up to a third of patients develop persistent activity-related dyspnea without evidence of pulmonary hypertension at rest. In such individuals, dyspnea appears to be associated with rela...
Following pulmonary embolism (PE), up to a third of patients develop persistent activity-related dyspnea without evidence of pulmonary hypertension at rest. In such individuals, dyspnea appears to be associated with relatively high inspiratory neural drive (IND, assessed via diaphragm electromyography) during exercise. Excessive IND is multifactorial, but the effects of regional pulmonary capillary hypoperfusion and increased physiological dead space may be contributory. We aimed to determine the effect of iNO on IND, perceived dyspnea intensity, and exercise endurance in patients post-PE. We undertook a randomized, double-blind, placebo-controlled crossover study where 14 symptomatic individuals post-PE completed constant work rate cycle exercise tests while breathing iNO (40 ppm) or placebo, on separate days. Detailed measurements of expired gas, respiratory neuromechanics, and perceived dyspnea were acquired at rest and throughout exercise. iNO administration, compared with placebo, was associated with reduced isotime IND and breathing effort (esophageal pressure-time product of inspiratory muscles) by 9 ± 8 and 19 ± 35%, respectively (both < 0.01), increased exercise endurance time by 27 ± 12% ( < 0.001), and reduced isotime dyspnea ratings by 1 ± 1 Borg units ( = 0.011). The reduction in IND was related to reduced dyspnea ( = 0.59, < 0.018), which in turn, correlated with increased exercise endurance time ( = -0.60, < 0.024). At standardized exercise times, iNO was associated with small reductions in ventilatory requirements for CO and heart rate, and increased oxygen pulse, vs. placebo (all < 0.05). This study demonstrated that excessive IND contributed to troublesome dyspnea and exercise intolerance in individuals post-PE and that these could be partially mitigated by selective pulmonary vasodilation. The current study confirmed that excessive inspiratory neural drive contributed to troublesome dyspnea and exercise intolerance in individuals with a history of pulmonary embolism and that these could be partially mitigated by acute selective pulmonary vasodilation via inhaled nitric oxide. This study increased our understanding of the complex mechanisms of exertional dyspnea in individuals post-PE with persistent abnormal physiological responses during CPET.
Network control dynamics and subjective reactivity in physiological responses to psychosocial stress.
Antonio DS, Bigliassi M
J Appl Physiol (1985) · 2026 Mar · PMID 41665241 · Publisher ↗
The ability to endure psychosocial stressors is critical for mental and physical well-being. Clarifying mechanisms that differentiate high- from low-tolerant individuals may inform resilience-oriented interventions. This...
The ability to endure psychosocial stressors is critical for mental and physical well-being. Clarifying mechanisms that differentiate high- from low-tolerant individuals may inform resilience-oriented interventions. This exploratory study aimed to predict tolerance to the socially evaluated cold pressor test (SECPT) from a multimodal set of psychological ratings and physiological markers, quantifying how psychophysiological responses account for individual differences in acute psychosocial stress tolerance. Thirty healthy adults completed a 5-min baseline followed by the SECPT. Self-reported perceptual and affective responses, electrodermal activity, and electroencephalography [EEG; sensor-level Granger connectivity computed over a frontoparietal (FPN) scalp montage] were acquired throughout; a brief semi-structured interview complemented quantitative findings. Models were evaluated with stratified fivefold cross-validation. A random forest regressor with a square-root-transformed duration target explained 23.5% of the variance. Two composite features emerged as primary, directionally opposite predictors: the stress response index showed a positive effect; higher perceived stress, arousal, and pain were associated with longer tolerance, whereas FPN causal connectivity showed a negative effect; stronger directed influence predicted shorter tolerance. The SECPT manipulation produced a perceptual profile of higher stress, pain, and arousal with lower affective valence and perceived dominance. Sympathetic activity predominated, with an early peak and a trend toward habituation. Global FPN connectivity was attenuated, most notably over parietal, central-parietal, and frontal interhemispheric circuits. Together, these results indicate that tolerance reflects an interplay between subjective reactivity and network control dynamics. The findings provide initial, mechanistically informed markers of psychosocial stress tolerance and motivate larger studies to test generalizability and temporal dynamics. We integrated self-report, electrodermal activity, and EEG connectivity focused on the frontoparietal network (FPN) to predict psychosocial stress tolerance. A random forest model explained 23.5% of the variance. Two composites showed opposing effects: a higher stress response index predicted longer tolerance, whereas a stronger FPN causal connectivity predicted shorter tolerance. SECPT produced sympathetic-dominant arousal and attenuated global FPN connectivity. Findings provide insights into the mechanisms underlying stress tolerance in psychosocial contexts.
Skeletal muscle morphology and metabolism in patients with heart failure compared to healthy controls: a systematic review and meta-analysis.
Prokopidis K, McCluskey M, Schmid V … +3 more , Irlik K, Florek S, Phillips BE
J Appl Physiol (1985) · 2026 Apr · PMID 41665168 · Publisher ↗
Heart failure (HF) is characterized by altered skeletal muscle morphology. The aim of this systematic review and meta-analysis was to explore cross-sectional differences in muscle morphology and metabolism between patien...
Heart failure (HF) is characterized by altered skeletal muscle morphology. The aim of this systematic review and meta-analysis was to explore cross-sectional differences in muscle morphology and metabolism between patients with HF and healthy controls. A literature search of studies was conducted from inception to February 2025 across PubMed, Scopus, Web of Science, and the Cochrane Library. Eligible studies compared skeletal muscle morphological differences via the vastus lateralis from patients with HF versus healthy controls. A meta-analysis was conducted using the random effects inverse-variance model. Thirty-five studies were included in this study. Patients with HF displayed similar absolute muscle fiber areas (type I, II, IIa, IIx), lower relative type I fiber area [MD: -8.3%, 95% confidence interval (95% CI): -12.3 to -4.4], and higher type II (MD: 11.3%, 95% CI: 7.3 to 15.4) and IIx areas (MD: 7.4%, 95% CI: 4.3 to 10.4) versus controls. Capillaries per fiber were reduced in patients with HF (MD = -0.28, 95% CI: -0.52 to -0.03), particularly for type IIa (MD = -0.30, 95% CI: -0.54 to -0.06) and IIx fibers (MD = -0.35, 95% CI: -0.55 to -0.15). IGF-1 was lower (-19.4 mRNA AU, 95% CI: -36.3 to -2.5), and myostatin was elevated (16.1 mRNA AU, 95% CI: 2.9 to 29.2) in patients with HF. Citrate synthase, 3-hydroxyacyl-CoA-dehydrogenase, and succinate dehydrogenase were significantly lower in patients with HF ( < 0.05). In conclusion, HF is characterized by reduced relative type I fiber area, increased type II/IIx, reduced capillarization, altered anabolic/catabolic markers, and impaired energy metabolism enzymes in skeletal muscle compared with healthy controls.
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