Physiologia

Prediabetes, a pivotal phase in glucose metabolism between normalcy and diabetes, exerts a profound influence on the aging process and the risk of age-related diseases. This comprehensive review delves into the intricate web of blood-based biomarkers that collectively expedite senescence, marking the transition from a state of health to age-related complications. Key findings underscore the significance of diverse biomarkers, such as telomere length, p16INK4a, senescence-associated secretory phenotype (SASP) factors, DNA methylation clocks, advanced glycation end products (AGEs), inflammatory and oxidative stress markers, circulating hormones, and additional factors such as folate, B12, and osteocalcin. Not only do these biomarkers serve as indicators of senescence but they also actively fuel chronic inflammation, oxidative stress, and metabolic dysregulation, all of which contribute to accelerated aging. The implications of this understanding are profound, as prediabetes emerges as a critical period in an individual’s life, influencing various physiological systems, including the vascular and neural systems, metabolic functions, hormonal regulation, and bone health. Recognizing the profound influence of prediabetes on senescence provides a foundation for personalized intervention strategies to mitigate age-related complications and promote healthy aging. Future research directions call for a more diverse array of biomarkers, the in-depth exploration of their roles, and the development of tailored precision medicine strategies to ensure a holistic understanding and effective management of prediabetes-induced senescence and its implications for aging. This knowledge has far-reaching implications for public health and clinical practice, emphasizing the need for early detection and intervention in prediabetic individuals to enhance the quality of life in an aging population with diverse needs. Full article

(1) Background: The influence of estrogen on cognitive and perceptual functions is debated. Some research suggests that estrogen increases arousal, improving cognitive function, while others propose that increased arousal might reduce performance in certain tasks. This study investigates the effects of menstrual cycle phase and estrogen levels on lightness perception in cycling women and hormonal contraceptive (HC) users. (2) Methods: Sixteen women (nine with natural cycles and seven HC users) completed three sessions aligned with different menstrual cycle phases. During these sessions, participants adjusted the luminance of five test stimuli (representing blue, green, green-yellow, yellow, and red) until they matched a flickering reference white stimulus. Lightness was calculated as the ratio of the reference stimulus luminance (5 cd/m²) divided by the test luminance required to match. Estrogen levels were also determined for each participant from saliva samples collected on the morning of each session. The effects of wavelength and menstrual cycle phase on lightness perception were analyzed, followed by post hoc comparisons and correlations between lightness perception and estrogen levels for both cycling women and HC users. (3) Results: Lightness varied by menstrual phase (MCP) in cycling women and was slightly higher during the low estrogen menstrual phase compared to peri-ovulation or luteal phases. In HC users, lightness measures were equivalent across phases. For cycling women, lightness was negatively correlated with estrogen for the green and green-yellow stimuli. There were no such associations among HC users. (4) Conclusions: This report challenges the concept that high estrogen phases of the menstrual cycle always positively influence perception. Conversely, these results revealed that—at least in cycling, non-hormonal contraceptive users—lightness perception was both at a maximum during the low estrogen menstrual phase and negatively associated with estrogen levels across all tested wavelengths. Full article

The aging of the global population is a significant and complex phenomenon with far-reaching implications for healthcare systems and society. By 2030, it is projected that the number of individuals over the age of 65 will increase by nearly 1 billion, largely due to advancements in healthcare and improvements in quality of life. Aging is a multifaceted process that encompasses a wide array of changes, spanning from the cellular level to the intricate physiological systems of the human body. At the central nervous system level, aging represents a major risk factor for conditions such as depression and cognitive impairment, which are likely linked to neuroinflammatory processes and can potentially lead to more severe dementias, including Alzheimer’s disease (AD). The higher prevalence of AD in women compared to men has led to speculation that the onset of menopause and associated phenomena, particularly the decline in estrogen levels, may play a role in the development of the disease. Furthermore, research has shown that physical exercise confers both physical and mental health benefits to older adults, with women potentially experiencing the greatest advantages. Understanding the multifaceted nature of aging and its implications for health will ensure that older adults receive the support and care essential for maintaining their health and quality of life. Full article

Background: The positive effects of prolonged every-other-day (EOD) feeding include decreased body weight and prolonged life span, but also changes in liver metabolism and functions. In the present paper, our aim was to examine the expression of adiponectin (ADIPOQ), leptin, and their receptors (ADIPOR1, ADIPOR2, and LEPR) in the liver tissue of EOD-fed mice in comparison to ad libitum (AL)-treated mice. Methods: After 9 months of EOD treatment, liver tissue was harvested and prepared for analysis. RT-PCR, protein semi-quantitative estimation, and cellular immunolocalization was performed. Results: We noted a decreased expression of leptin in the liver tissue of the EOD male mice in comparison to the AL mice on the protein level. ADIPOQ receptor R1 protein expression was decreased in the liver of EOD-fed male mice, while the expression of ADIPOR2 on the protein level was increased in the EOD animals. Conclusions: To the best of our knowledge, this is the first report showing ADIPOQ and leptin immunolocalization in the liver tissue in a dietary regime experiment. Decreases in leptin expression and IL-6 expression in liver tissue and increases in ADIPOR2 expression may be partly responsible for the beneficial effects of EOD treatment in the liver, including the decrease in inflammation. Further studies are needed to establish whether these changes depend on factors like the type of treatment, species, strain, gender, time of treatment, and others. Full article

When thinking of skin disease, cancer comes up almost immediately as an example. While the American Cancer Society lists 6 major cancer types, the National Institute of Arthritis and Musculoskeletal and Skin Diseases identifies 13 significant benign skin disorders, reflecting the diversity of skin conditions in dermatology. This topical review aims to provide an overview of the pathophysiology of these major skin cancers and disorders and to summarize conventional diagnostic methods and current treatment approaches. Full article

Heat stress and cutaneous capsaicin application act independently to reduce mean arterial blood pressure (MAP) at rest. The present study investigated whether a mixed intervention might alleviate to a greater extent the hypertensive response to isometric exercise. An end-exercise systolic blood pressure (SBP) lower than 215 mmHg or higher than 220 mmHg was set for the inclusion in the group observed with typical (CON, n = 9) or hypertensive (HRE, n = 8) response to dynamic exercise, respectively. The participants performed four trials held in thermoneutral (TN:23 °C) or hot (HT:33 °C) conditions with capsaicin (CA:4.8 mg·patch⁻¹) or placebo (PL) patches (12 × 18 cm²) applied to their two quadriceps, left pectoralis major and left scapula. The trials comprised: a 5 min baseline period preceding patch application, a 30 min rest period and a 5 min isometric handgrip exercise (20% maximal voluntary contraction, 10.1 ± 1.9 kg). Thermoregulatory and cardiovascular data were analyzed using mixed three-way ANOVA. End-resting MAP and pain sensation were higher in PL-TN (p = 0.008) and CA-HT (p = 0.012), respectively. End-exercise SBP tended to be higher in HRE individuals across environments (p = 0.10). Total peripheral resistance and MAP remained lower in HT across groups (p < 0.05). Despite the alleviating effect of the heat stressor, an augmented burning sensation-induced peripheral vasoconstriction might have blunted the pressure-lowering action of capsaicin. Full article

Polyunsaturated fatty acid (PUFA) metabolites play important roles in the modulation of vascular tone, heart rate variability (HRV), and cardiovascular diseases. This study was undertaken to examine the relationship between HRV and the plasma levels of essential acids. Methods: Highly trained cross-country skiers participated in the study (n = 19). Time-domain and frequency-domain HRV analyses were performed. The plasma levels of fatty acids were determined using gas–liquid chromatography. Results: Plasma eicosapentaenoic acid and docosahexaenoic acid were found to be negatively correlated with resting heart rate (HR) (p = 0.026). The plasma levels of alpha-linolenic acid (ALA) were positively associated with the relative value of high-frequency power (rs = 0.465, p = 0.045) and negatively correlated with the sympathovagal balance ratio (rs = −0.493, p = 0.032) and the absolute and relative values of low-frequency power (rs = −0.490, p = 0.028). The plasma levels of arachidonic acid (ARA) were positively associated with the relative value of high-frequency power (rs = 0.59, p = 0.006) and negatively correlated with the sympathovagal balance ratio (rs = −0.54, p = 0.017) and the relative values of low-frequency power (rs = −0.52, p = 0.022). No correlation was found between n6/n3 and HRV parameters except for HR and pNN50. Conclusions: n-3 PUFAs and ARA play an important role in the autonomic regulation of heart rate in highly trained skiers. Athletes with substantial deficiencies in plasma ALA and excess levels of ARA had increased sympathetic and decreased parasympathetic activity. Full article

Nitrogen is the most commonly managed mineral nutrient in olive groves because it is essential for plant growth. The precise management of N fertilization in olive cultivation is still not fully clarified, but it is essential for providing sustainable production. A nitrogen fertilizer experiment with olive trees (cv. Kalinioti) was carried out over a six-year period. Seven levels of nitrogen fertilizer given as ammonium nitrate (control, 1, 2, 3, 4, 5, and 6 kg/tree) were annually applied in order to determine the effect of nitrogen on vegetative growth, fruit set, fruit weight, yield, maturation index, and leaf N, P, and K concentrations. The results indicate that, under these conditions, application of up to 4 kg NH₄NO₃/tree significantly increased yield to 62.5 kg/tree compared to the control (37.09 kg/tree). The positive effect was attributed to the initial and final fruit set increases (7.63 and 3.73%, respectively at 4 kg NH₄NO₃/tree). However, the weight of 100 olives (W₁₀₀ = 331 g) at 4 kg NH₄NO₃/tree obtained during harvest was considerably lower compared to the control (W₁₀₀ = 384 g). Higher nitrogen rates decreased yield while increasing overall shoot growth. Nitrogen fertilization did not significantly influence the oil content of olive fruit. Fruit weight, maturation index, and concentration of oil reached maximum levels in the beginning of December, indicating a suitable start to olive harvesting. The concentration of N in olive leaves increased from 1.23% to 2.38% as fertilizer levels increased from 0 to 6 kg NH₄NO₃. Maximum yield was achieved at a level of 6 kg NH₄NO₃/tree, which corresponded to 2.01% N in leaves. The results suggest that application of 3 kg NH₄NO₃/tree can be recommended for table olive production, due to the fact that fruit weight was not decreased, while fertilization with 4 kg NH₄NO₃/tree was suitable for oil olives. Full article

Sleep staging has a very important role in diagnosing patients with sleep disorders. In general, this task is very time-consuming for physicians to perform. Deep learning shows great potential to automate this process and remove physician bias from decision making. In this study, we aim to identify recent trends on performance improvement and the causes for these trends. Recent papers on sleep stage classification and interpretability are investigated to explore different modeling and data manipulation techniques, their efficiency, and recent advances. We identify an improvement in performance up to 12% on standard datasets over the last 5 years. The improvements in performance do not appear to be necessarily correlated to the size of the models, but instead seem to be caused by incorporating new architectural components, such as the use of transformers and contrastive learning. Full article

The objective of the present review was to evaluate the time-course of recovery of biochemical marker levels and physical performance after strenuous military training, and identify which biomarkers are affected. A systematic literature search was conducted using the databases MedLine (Ovid) and Web of Science (WoS) to identify studies until January 2023. Varying relevant search terms were used, related to military training, Special Forces, physical performance, and biomarkers. Records were based on strict inclusion and exclusion criteria. Twelve studies met the inclusion criteria and were selected for this review. A variety of physiological and psychological markers were measured, and military training lasted from 4 to 62 days, with recovery periods varying from 24 h to 6 weeks. Among these studies, full recovery was observed in two studies, while seven studies showed almost full (79–90%) recovery, and in three studies, 44–63% of markers recovered after the measured recovery period. However, in some studies, additional markers could be defined as recovered, depending on the criterion for recovery. In the majority of the studies, most of the measured variables recovered during the follow-up, but often, some variables remained unrecovered, and at times, only modest recovery was seen. It is important to point out that recovery duration depends on the duration and intensity of the military training stressor. Overall, resolution varies between the markers, and sometimes, recovery might not occur, even after prolonged recovery. Therefore, it is important to measure the recovery status of soldiers with both biomarkers and physical performance markers, especially after strenuous training, to maximize operational capability during prolonged missions. Full article

Firefighters are exposed to dangerous and often traumatic events due to the nature of their occupational demands. This repeated exposure to trauma combined with stressful work demands increases their risk for negative physiological and psychological health outcomes. The high prevalence of adverse health outcomes highlights the need for interventions to improve resiliency in firefighters. Resiliency is the ability to reduce the effect of crisis, rebound from adversity, and recover to pre-stimulus homeostasis. When traumatic exposures are unavoidable, as is the case with firefighters, it is important to buffer the resulting consequences on health. While resilience has a genetic component, interventions targeting physiological, psychological, and social components have been successful at improving resilience. These factors are of specific interest as increases in resilience have been linked to improved PTSD symptomology/severity, depression, anxiety, autonomic nervous system activation, hypothalamus–pituitary axis balance, and brain-derived neurotrophic factor. Therefore, the purpose of this review is to identify physiological and psychological components associated with resiliency and discuss strategies that may improve those components to ultimately increase resiliency in firefighters. The strategies discussed include exercise, social support, and mindfulness. Full article

The roles of 17β estradiol (E2) and progesterone (P4), the primary female sex hormones, are pivotal in regulating various aspects of metabolism. E2 influences food intake, energy expenditure, adipose tissue distribution, and insulin sensitivity across multiple tissues. Meanwhile, P4 impacts energy expenditure, electrolyte balance, amino acid oxidation, muscle protein synthesis, and glucose metabolism. The interactions between these hormones affect macronutrient utilization, both at rest and during exercise. Acknowledging the need to incorporate sex hormone perturbations in research, this paper explores the current landscape of study design and menstrual cycle tracking for female-specific sport research. It emphasizes the importance of standardization in terminology, hormone phases, reference values, and affordable hormone detection methods to advance our understanding of how the menstrual cycle influences female athletes. Full article

Background: There are no published data on the training-load magnitude or distribution in elite international-level boxers preparing for a major competition nor on the training load’s relationship with objective and subjective training markers. Methods: Twelve elite boxers (eight males and four females) preparing for the 2018 Commonwealth Games were monitored during training for 12 weeks. The training load (TL), change in creatine kinase (ΔCK), and wellness variables were measured daily but were amalgamated into average weekly values over the 12-week period for weekly comparisons. The relationships between the TL, ΔCK, and wellness variables were also assessed. Results: The significant (p < 0.001) main effects of the week with large and moderate effect sizes were noted for the TL and ΔCK, respectively, with weeks 9 and 12 in the competition-specific and taper phases showing the greatest differences, respectively. For wellness, only the muscle condition showed a significant change over time (p < 0.001). There were significant (p < 0.05) small–moderate correlations between the TL, ΔCK, and wellness variables. Conclusions: This is the first study to describe the weekly training loads and responses to training of elite international boxers across a 12-week pre-competition training period in preparation for a major competition. The findings within this study report that elite international boxers have high chronic training loads that change between training blocks to put emphasis on different qualities. Monitoring the indirect muscle damage through CK may provide further information on the internal training responses in boxers. Full article

Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting side-effect resulting from numerous neurotoxic chemotherapies that damages the peripheral nerves, alters sensations in the hands and feet, causes burning and shooting pains, and impairs a patient’s quality of life (QoL). There are limited established interventions to help improve CIPN symptoms. There is only one pharmacological agent (Duloxetine) for treatment of CIPN; however, it only has mild benefit, signaling a critical need for alternative management options to manage patient symptoms. Multiple studies suggest therapeutic benefits of exercise in cancer care to improve physical and psychological functioning; however, the benefits regarding CIPN symptoms and physical function are less clear. This narrative review synthesizes research articles investigating the effect and mechanisms induced by different exercise programs for patients with taxane-induced peripheral neuropathy (TIPN) symptoms and function. The overall incidence, manifestations, characteristics, and mechanisms of CIPN are also discussed. While some studies in this narrative review demonstrated that exercise programs may have benefits on sensory and motor TIPN symptoms in some but not all patients, there are consistent benefits of improved QoL and physical function across most patients. This narrative review highlights the need for future research to confirm the effects of exercise for TIPN, with a focus on other important components, including the effect of exercise adherence, type, and supervision level. Full article

Breath-hold diving has been traditionally practiced for professional and recreational reasons and has recently emerged as a competitive sport. The physiological response during breath-holding, also known as diving response, consists mainly of bradycardia and peripheral vasoconstriction. Elite apneists can suppress the urge to breathe, sustain greater arterial desaturation and develop pronounced bradycardia, thus accomplishing impressively long breath-hold times. This study explored physiological responses during static apnea and their association with apnea duration in breath-hold divers with high physiological adaptations acquired from long-term apnea training. Nine well-trained competitive divers held their breath for as long as possible while floating motionlessly in a swimming pool (26–27 °C), simulating an actual “static apnea competition”. Long apnea durations (302 ± 60 s) as well as severe oxygen desaturation (minSaO₂ 46 ± 11%) and bradycardia (minHR 49 ± 8 bpm) were achieved. Apnea duration was positively correlated with forced vital capacity (r = 0.771) and apnea duration until initiation of desaturation (r = 0.736) and negatively correlated with minSaO₂ (r = −0.672) (p < 0.05). Moreover, minHR during apnea was correlated with pre-apneic hemoglobin concentration (r = 0.685) (p < 0.05). The prolonged apnea durations achieved by the well-trained divers in this study, while performing maximum immersed static apnea under competitive simulated conditions, were related to their high lung volumes and their delayed and profound O₂ desaturation, whereas their bradycardic response was not a decisive factor. Full article

Background: The purpose of this study is to ascertain the reliability of two 15-s sprint cycling tests in men and women to estimate the maximum lactate accumulation rate (VLamax). Methods: Eighteen men and twelve women completed two sprint sessions over 1 week. A 10 min warm-up preceded the obtaining of a 3 µL blood lactate (BLC) sample, after which a 15 s sprint was completed; cyclists then rested passively while multiple lactate samples were taken until the levels peaked. Trial differences and reliability across trials were analyzed using a paired-sample t-test, Pearson’s correlation, Intraclass correlation (ICC), and Bland–Altman analysis with α = 0.05 for all tests; data are reported as mean ± sd. Results: Power (W) was similar across trials (773.0 ± 143.5 vs. 758.2 ± 127.4; p = 0.333) and the coefficient of variation (CV) of 4.7%. VLamax (mM·L⁻¹·s⁻¹) was similar (0.673 ± 0.024 vs. 0.635 ± 0.237; p = 0.280), but only moderately reliable across trials with CV, ICC, and R values of 18.6%, 0.661, and 0.67, respectively. Pre-BLC and peak BLC CV were 45.6 and 23.3%, respectively. Conclusions: A 15 s VLamax cycling sprint is moderately reliable, possibly affected both by the lactate measurement and other variables used in the calculation. More research may offer ways to improve reliability. Full article

Soybeans are vulnerable to drought and temperature increases potentially induced by climate change. Hydraulic dysfunction and stomatal closure to avoid excessive transpiration are the main problems caused by drought. The vulnerability of soybeans to drought will depend on the intensity and duration of water stress. The purpose of this study was to determine if the use of cover crops (CCs) can influence the gas exchange potential of glyphosate-tolerant soybeans when the vapor pressure deficit (Vpd) increases. This two-year study was conducted in an open experimental field comprising direct seeding plots with or without CCs. Stomatal conductance (Gs) was measured five times on the same identified leaves following glyphosate-based herbicide application. These leaves were then collected in order to observe the stomata and foliar traits with a scanning electron microscope. The Vpd was calculated concomitantly to Gs measurements at the leaf surface. The results suggest that the use of CCs promotes phenotypic change in soybean leaves (more elaborate venation and a higher abaxial stomatal density), which in turn may enhance their tolerance to drier conditions. In 2019, Gs could be up to 29% higher in plots with CCs compared to those without CCs with similar Vpd values. This study shows that the benefits of using CCs can be observed via the morphological development strategies of the crop plants and their higher tolerance to drought. Full article

This study examined the effects of two different acute bouts of treadmill running (e.g., steady-state moderate-intensity exercise (SSE) and high-intensity interval exercise (HIIE)) on adipokine (e.g., adiponectin, leptin, and omentin) concentrations in individuals with moderate stages of chronic kidney disease (CKD). Fourteen participants (8 females and 6 males) (age 58.7 ± 9.7, height (cm) 168.5 ± 9.7, weight (kg) 83.5 ± 18.2) were classified as having moderate stages of CKD (stages G3a and G3b; estimated glomerular filtration rate (eGFR) between 59 and 30 mL/min/1.73 m²). Participants completed 30 min of either SSE at 65% oxygen consumption reserve (VO₂R) or HIIE for 3 min at a 90% VO₂R separated by 2 min of slow walking (20% VO₂R) in a randomized, crossover design on a treadmill. Venous blood samples were obtained at baseline, 1 h, and 24 h post exercise. Data were analyzed using a two by three repeated measures ANOVA (p < 0.05). There were no significant differences in adiponectin (p < 0.353), leptin (p < 0.084), and omentin (p < 0.235) concentrations between SSE and HIIE. Similarly, no significant differences were seen between the sampled time points for either aerobic exercise condition. In conclusion, this study demonstrated there were no changes in adiponectin, leptin, or omentin concentrations when performing an acute bout of HIIE or SSE for 30 min, at 1 or 24 h post exercise. Future studies should seek to either increase the duration of the exercise bout or identify different adipokines to examine for patients experiencing moderate stages of CKD. Full article

The physiological mechanisms for releasing and resolving gravitational ischemia in the brain, and their susceptibility to malfunction, may play an important role in a variety of neurological illnesses. An astronaut on a space walk in a micro-gravity environment may be susceptible to neuro-ocular symptoms associated with unopposed gravity-resistance mechanisms for partially preventing gravitational ischemia in the brain, and for attenuating its impact—mechanisms which may be required for normal brain physiology on Earth. Astronauts on the International Space Station typically breathe a mixture of gasses similar in composition to what they breathed on Earth, following the 1967 death of three astronauts, including Ed White, by fire on the Apollo 1 spacecraft, which was carrying 100% oxygen. For the last decade, astronauts have been studied extensively by flight physicians regarding the commonly experienced symptoms of VIIP, or ‘visual impairment and intracranial pressure’ syndrome. In this paper, we compare VIIP syndrome to the neuro-ocular and Parkinson’s-like symptoms which occurred during and after the 1918–1919 influenza pandemic. The common denominator may be gravitational ischemia in the brain, and the mirror-imaging failed mechanisms for its release (in influenza) versus unopposed gravity-resistance mechanisms (in astronauts). Some research has suggested that astronauts may benefit from breathing oxygen concentrations somewhat higher than 20%, and under slightly elevated pressure. These may possibly prevent maladaptive mechanisms leading to Alzheimer’s- or Parkinson’s-like illness by compensating for impaired mechanisms for releasing and resolving gravitational ischemia in the brain. Full article