Physiology international最新文献

Purpose: To assess the accuracies of airway resistance (Raw) and compliance (Crs) calculations using the expiratory time constant (RCexp) method as well as the accuracy of Pmus estimation in obstructive lung models.

Methods: A Respironics V60 ventilator was connected to an active lung simulator. The driving pressure was maintained at 5-10 cmH2O and positive end-expiration pressure (PEEP) was 5 cmH2O. Maximal Pmus, estimated based on equations of motion and respiratory mechanical properties, was calculated by the RCexp method to derive respiratory system compliance (Crs) and inspiratory (Rinsp) and expiratory (Rexp) resistance.

Results: During PAV, the assist proportion was adjusted to 55% and 40% with Pmus of 5 and 10 cmH2O, respectively. Pmus measurement errors were <20% of the preset values in most lung conditions. In the active lung model with PAV, an overestimation of Raw was found in the normal resistance condition, and Rinsp was underestimated in the severe obstructive model (P < 0.01). Crs was overestimated significantly except in the severe obstructive model at a Pmus of 10 cmH2O (all P < 0.01). Using the RCexp method, the target of ≤20% between the calculated and preset values in airway resistance was achieved in most obstructive models at a Pmus of 5 cmH2O.

Conclusions: The RCexp method might provide real-time assessments of respiratory mechanics (elastance and resistance) in the PAV mode. With low inspiratory effort, the estimation error was acceptable (<20%) in most obstructive lung models.

Purpose: The determinants of aerobic capacity are oxygen delivery by the cardiopulmonary system and oxygen extraction by the skeletal muscles. However, the impact of the oxygen extraction capacity of the skeletal muscle is unclear. This study aimed to examine the associations between aerobic capacity; muscle strength, endurance, mass, and quality; and oxygen extraction capacity.

Methods: Twenty-seven healthy young men (mean age, 20.7 ± 0.8 years; body mass index, 21.6 ± 3.2 kg m-2) were recruited. The following parameters were determined: peak work rate (WR) and oxygen uptake (V˙O2) corrected for body mass using the cardiopulmonary exercise testing; muscle strength and endurance using isokinetic muscle testing; muscle mass using bioelectrical impedance; muscle quality (muscle echo intensity) using an ultrasound imaging device, and muscle oxygen extraction rate (MOER) using near-infrared spectroscopy. Multiple regression analysis was performed using WR/kg peak and V˙O2/kg peak as dependent variables and each assessment index as an independent variable.

Results: Multiple regression analysis with WR/kg peak as the dependent variable resulted in the adoption of SMI (β = -0.41, P = 0.036), muscle echo intensity (β = -0.45, P = 0.012) and ΔMOER (β = 0.73, P < 0.001) as significantly associated factors. Multiple regression analysis with V˙O2/kg peak as the dependent variable resulted in ΔMOER (β = 0.65, P = 0.001) being adopted as a significantly associated factor.

Conclusion: These findings suggest that muscle oxygen extraction rate is associated with aerobic capacity. MOER is a useful indicator because it is not affected by body mass.

Background: Maintaining intrinsic articular cartilage homeostasis is essential for the health of cartilage. However, the impact of aerobic exercise of varying intensities on the articular cartilage homeostasis has never been studied. This study aims to elucidate the influence of different aerobic exercise intensities on the anabolic and catabolic processes within articular cartilage.

Methods: Forty-eight male C57BL/6J mice, aged 7 weeks, were divided into 4 aerobic exercise groups and 1 control group. The aerobic exercise groups were subjected to both acute and chronic exercise protocols with varying intensities of 8, 12, 16, 20, and 24 m min-1. Total RNA from the knee joint cartilage was extracted in both phases to quantify mRNA of anabolic (Sox9, Col2a1, and Acan) and catabolic (MMP-13 and ADAMTS5) markers. In the chronic exercise, articular cartilage thickness and chondrocyte density were histologically assessed. Additionally, immunohistochemical staining quantified relevant molecules involved in cartilage metabolism.

Results: In the acute exercise, the 8 m min-1 group exhibited reduced ADAMTS5 expression compared to the control, 16 m min-1, and 24 m min-1 groups. Chronic exercise showed enhanced articular cartilage thickness in both the 8 and 12 m min-1 groups relative to the control group. Moreover, the 8 m min-1 group demonstrated elevated aggrecan levels in comparison to both the control and 24 m min-1 groups. Additionally, the 24 m min-1 group exhibited significantly higher ADAMTS5 levels than the control group.

Conclusion: Our findings suggest that consistent low-intensity aerobic exercise suppresses catabolic molecule expression in articular cartilage, thereby fostering anabolic activity. Conversely, continuous high-intensity aerobic exercise can potentially disrupt cartilage homeostasis by enhancing catabolic processes. This dichotomy underscores the need for balanced exercise regimens to maintain cartilage health.

Kettlebell as a sport has gained recognition worldwide. We characterized the physiological responses induced by a simulated kettlebell competition routine in experienced kettlebell athletes (n = 26) in a two-group, pre-post plus short-term follow-up, non-randomized experiment. The experimental group (EXP) included 13 kettlebell athletes, while the control group (CON) consisted of 13 individuals with prior recreational exposure to kettlebell activities. EXP performed a 10-minute-long, long-cycle kettlebell routine, whereas CON engaged in seated rest. Cardiovascular and neuromuscular outcomes were measured at rest, after warm-up, during exercise, at 0 (immediately post), 5 and 15 min into recovery. Group-by-time interactions revealed that the 10-minute-long, long-cycle kettlebell routine increased (P < 0.05) the levels of all outcomes (e.g. heart rate, blood pressure, blood lactate) (range of effect sizes: -0.9-8.9) with many outcomes remaining well above baseline at 5 and 15 min into recovery. A notable exception was a lack of change in maximal squat strength. Kettlebell experience and mass correlated with changes in oxygen uptake (ΔVO2) and in ventilation (ΔVT) (r = -0.70, 0.64, -0.87, and 0.73, respectively, P < 0.05) in EXP. Kettlebell routine evoked significant changes in all physiological variables (respiratory and cardiovascular), out of which the heart rate (HR), diastolic blood pressure (DBP), rate pressure product (RPP), and blood lactate (BL) outlasted the routine for at least 15 min. Future studies should longitudinally examine physiological responses to kettlebell training throughout a season. Long-cycle kettlebell routine adds to the repertoire of evidence-based exercise options for high-intensity exercise.

Background: Fertilization check performed at the 18th hour following classic in vitro fertilization procedure (IVF) or intracytoplasmic sperm injection (ICSI) is a critical stage in assisted reproduction. The success of the treatment is significantly reliant on the quantity of zygotes exhibiting two pronuclei. Consequently, low fertilization rates or complete fertilization failure are highly undesirable outcomes for both patients and reproductive specialists. Applying additional calcium ionophore for oocyte activation subsequent to ICSI may offer benefits and potentially enhance treatment outcomes, particularly for patients who have experienced low or absent fertilization rates (FR) in previous treatment cycles. The aim of the study is to evaluate the efficacy of Ca2+ ionophore application for oocyte activation.

Methods: A retrospective analysis of 924 oocytes obtained from 120 patients who underwent ICSI cycles with a history of low or no fertilization as a result of previous unsuccessful treatment rounds. The next ART cycle followed with additional oocyte Ca2+ ionophore activation applied in 57 of the cases in order to optimize the treatment process (Group 1), and 63 patients were included and their outcomes followed as a control group (Group 2).We conducted a comparative analysis of results in both groups. The study's primary outcomes encompassed fertilization, cleavage embryo quality, blastocyst rate, and established clinical pregnancies.

Results: At day 1 fertilization check we had 274/386 zygotes (71%FR) in group 1 and 132/410 in group 2 (32.2%FR), (P < 0.0001). Twenty-two (34.9%) cycles in group 2 resulted in total fertilization failure (TFF). At the cleavage stage top-quality embryos from group 1 were significantly higher (P = 0.0021) in comparison to group 2. Forty-eight embryo transfers (ET) were performed in group 1 resulting in 41.67% clinical pregnancies versus 33 ET and only 4 pregnancies (12.12%) for group 2 (P = 0.0044).

Conclusions: The results confirm the appropriateness of assisted oocyte activation as an additional method in cases of previous fertilization failure cycles.

Anxiety is a common issue among university students, many of them experience anxiety, depression, and stress during their school life. This study aimed to compare the acute physiological stress responses of students divided into two groups according to their perceived anxiety levels (positive test anxiety, PTA+, and negative test anxiety, PTA-). Heart rate variability (HRV) and electrodermal activity (EDA) were used to assess stress.Thirty-one healthy volunteers participated in the study. Participants completed anxiety assessments, including the Westside Test Anxiety Scale (WTAS), the State-Trait Anxiety Inventory (STAI), and the Test State Anxiety Inventory (TSAI). Based on their scores, participants were categorized into PTA+ and PTA- groups. All participants underwent 24-h continuous recordings of pulse and electrodermal activity (EDA) on two separate occasions: one day prior to a written exam and during a designated exam-free day serving as a baseline control.We compared the HRV and EDA data obtained on a regular day and on an exam day between the two groups. Results showed that the PTA+ group had significantly higher heart rate, stress index, low frequency, and short-term detrended fluctuation analysis (DFAα1) on the exam day. The tonic EDA component was also higher in the PTA+ group. Stress-related HRV and EDA parameters were negatively correlated with exam scores.In conclusion, the study found that physiological stress indicators obtained from HRV and EDA are associated with perceived exam anxiety in students.

Background: Whole-body vibration (WBV) is used to enhance physical performance in sports and rehabilitation. The present study analyzed the effects of remobilization with WBV on the soleus muscle of Wistar rats.

Methods: Twenty-eight animals were separated into four experimental groups (n = 7): CON (control); IM (immobilized); FR (immobilization and free remobilization); and WBV (immobilization and remobilization with WBV). The immobilization of the pelvic limb was carried out according to the standard protocol using a plaster cast for 15 days. For remobilization with WBV, a Frequency of 60 Hz was applied for 10 min, five days a week, for two weeks. After the remobilization period, the animals were euthanized, and the right soleus muscle was dissected followed by processing for histomorphometric analysis and immunolocalization of Aquaporin 1 (AQP1).

Results: We observed a reduced larger diameter in IM compared to CON, with restored values in WBV. For the estimation of connective tissue, a significant increase was observed in the immobilized groups, while a reduction was noted in the remobilized groups. AQP1 expression decreased significantly in IM and increased in WBV.

Conclusion: Immobilization caused morphofunctional damage to the soleus muscle, and remobilization with WBV is efficient and offers advantages over free remobilization.

This study explored the effects of fructose-induced obesity and metabolic disorders on peripheral inflammatory hyperalgesia, employing quantitative sensory testing with the von Frey test and measuring paw edema to assess inflammatory responses. Wistar rats were administered water or 10% fructose solution ad libitum over a period of 5 weeks. After intraplantar administration of inflammatory agents such as carrageenan (1 mg/paw), lipopolysaccharide (LPS; 100 µg/paw), or prostaglandin E2 (PGE2, 100 ng/paw), we conducted mechanical hyperalgesia tests and paw edema evaluations. The fructose diet resulted in dyslipidemia, elevated insulin and leptin plasma levels, insulin resistance, and increased epididymal and retroperitoneal adiposity compared to control animals. In response to inflammatory agents, the fructose group displayed significantly enhanced peripheral hyperalgesia and more pronounced paw edema. Our results demonstrate that fructose not only contributes to the development of obesity and metabolic disorder but also exacerbates peripheral inflammatory pain responses by enhancing prostaglandin sensitivity.

Background: While the acute effects of high-load resistance training on the force generating capacity of muscles have been widely examined, limited data exist on the relationship with the force-velocity profile (FV). Evidence suggests high sensitivity of the vertical FV profile to monitor changes in the muscle's mechanical properties according to the type of the exercise protocol. However, the interpretation of the findings seems not as straightforward. Therefore, the purpose of this study was to examine the effects of a high-load resistance training protocol on the muscle's mechanical properties during loaded jumps and on the vertical force-velocity profile (FV) in relation to maximal strength.

Methods: 29 resistance-trained male (mean age±SD: 35.4 ± 7.8 years) and 29 female athletes (mean age±SD: 32.5 ± 7.0 years) participated in the study. Five-repetition maximum (5RM) in back squat, unloaded countermovement jump (CMJ) and FV profile were assessed. Loaded jumps were performed against 25, 50, 75, and 100 percent of body mass. Participants performed exercise protocols corresponding to their 5RM. Immediately after, unloaded CMJ and FV profile measurements were repeated.

Results: A significant decrease in CMJ height (∼5-6%) and in average power (∼4%) was recorded for both men and women. The FV profile did not change after the exercise protocol; however, there was a significant decrease in theoretical maximal power (from 4 to 5%) and in theoretical maximal velocity (∼3%). Maximal strength was not associated with the changes in FV profile.

Conclusions: Findings suggest that an acute high-load exercise decreased vertical jump performance and maximal power output, but without a concomitant change in FV profile. The large interindividual variability in FV measures indicates a less straightforward connection of the applied exercise with the acute response in the FV profile, highlighting the complexity of the FV profile to monitor changes in response to an acute training load.

The global temperature rise will have extensive consequences on our organ systems, but hypohydration caused by reduced water intake or increased water loss through sweating plays the most relevant role. Many studies have already demonstrated the association between hypohydration and impaired exercise performance, but data related to the cardiac burden of hypohydration are scarce. This study is a sub-investigation of our large, prospective, self-controlled trial on the effects of hypohydration on cardiopulmonary exercise capacity with previously published results. In the current sub-study, we analyzed the impact of hypohydration on cardiac burden in this cohort of fifty healthy, recreational athletes during cardiopulmonary exercise test.Therefore, each participant underwent cardiopulmonary exercise test with a standardized ramp protocol twice, once in hypohydrated state and once in euhydrated state as control, and the cardiac markers Troponin T, NT-pro-BNP and Chromogranin A were measured before and after the exercise test at each state. Mean age was 29.7 years and 34% of probands were female. Hypohydration led to a reduced body water, a significant decrease in oxygen uptake and lower levels of power output. Yet, Troponin T, NT-proBNP, Chromogranin A and lactate levels did not significantly differ between the two conditions.In this study cohort, decreased exercise capacity during hypohydration was more likely due to impaired cardiac output with diminished plasma volume rather than measurable cardiac stress from fluid deprivation. However, whether these data are generalizable to a diseased cohort is left unanswered and should be addressed in future randomized controlled trials.