Variation In Physiological Responses Research Articles

The delta concept does not effectively normalise exercise responses to exhaustive interval training

ObjectivesThis study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training (HIIT) prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (V̇O2max) are taken into account to normalise relative exercise intensity. DesignRepeated-measures, within-subjects design with mixed-effects modelling. MethodEighteen male and four female cyclists (age: 36 ± 12 years, height: 178 ± 10 cm, body mass: 75.2 ± 13.7 kg, V̇O2max: 51.6 ± 5.3 ml·kg−1·min−1) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O2max as prescription benchmarks. On separate occasions, participants then completed four HIIT sessions of identical intensity (70%Δ) and format (4-min on, 2-min off); all performed to exhaustion. Acute HIIT responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability. ResultsGreater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (CV = 46 %) and 4.5 min (CV = 22 %), respectively. ConclusionsDue to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive HIIT across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method.

Understanding mechanistic variability in physiological and biochemical responses of pea cultivars (Pisum sativum L.) to ozone exposure

Increasing concentration of ground level O3 and its negative impacts on agricultural output is well documented, however, the response of leguminous crop plants is still sparsely cited. Given their nutritional richness, legume seeds are widely esteemed as a crucial dietary staple worldwide, prized for their abundance of oil, protein, dietary fiber, and low-fat characteristics. Termed as the “poor man's meat” due to their high-quality protein, they hold immense economic value. Acknowledging the significance of legumes, a field experiment was conducted to understand the physiological and antioxidant responses, stomatal characteristics, and yield response in three cultivars of Pisum sativum L. (K Agaiti, K Uday and K Damini), exposed to elevated ozone (O3). In the present study, Pisum sativum cultivars were subjected to ambient (control) and elevated (+15 ppb) concentrations of O3, using separate sets of OTCs. Elevated O3 stimulated the activity of the enzymes of Halliwell Asada pathway, which were responsible for the differential response of the three experimental cultivars. While K Agaiti and K Uday focused on upregulating their antioxidant defense, K Damini followed the strategy of biomass allocation. Test weight showed that K Damini was most efficient in succoring the yield losses under elevated O3. Under elevated O3, test weight reduced by 8.91%, 7.52%, and 5.1%, respectively, in K Agaiti, followed by K Uday and K Damini, rendering K Agaiti most sensitive to O3 stress. The present study not only helps us to elucidate the O3 sensitivity of the selected experimental cultivars, it also helps us in screening O3 tolerant cultivars for future agricultural practices.

Exploring the contribution of inter-individual factors to the development of physiological heat strain in older adults exposed to simulated indoor overheating.

Older adults are at elevated risk of heat-related mortality due to age-associated declines in thermoregulatory and cardiovascular function. However, the inter-individual factors that exacerbate physiological heat strain during heat exposure remain unclear, making it challenging to identify more heat-vulnerable subgroups. We therefore explored factors contributing to inter-individual variability in physiological responses of older adults exposed to simulated hot weather. Thirty-seven older adults (61-80 years, 16 females) rested for 8 hours in 31°C and 36°C (45% relative humidity). Core (rectal) temperature, heart rate (HR) and HR variability, mean arterial pressure (MAP), and cardiac autonomic responses to standing were evaluated at baseline and end-exposure. Bootstrapped least absolute shrinkage and selection operator (LASSO) regression was used to evaluate whether variation in these responses was related to type 2 diabetes (T2D, n=10), hypertension (n=18), age, sex, body morphology, habitual physical activity levels, and/or heat-acclimatization. T2D was identified as a predictor of end-exposure HR (with vs. without: 13 beats/min [bootstrap 95% CI: 6, 23]), seated MAP (-7 mm Hg [-18, 1]), and the systolic pressure response to standing (20 mm Hg [4, 36]). HR was also influenced by sex (female vs. male: 8 beats/min [1, 16]). No other predictors were identified. The inter-individual factors explored did not meaningfully contribute to the variation in body temperature responses in older adults exposed to simulated indoor overheating. By contrast, cardiovascular responses were exacerbated in females and individuals with T2D. These findings improve understanding of how inter-individual differences contribute to the development of heat-induced physiological strain in older persons.

The variability of physical enjoyment, physiological responses, and technical-tactical performance according to the bout duration of small-sided games: a comparative study between female and male soccer players

BackgroundThis study aimed to compare various factors, namely perceived enjoyment (PE), percentage of peak heart rate (%HRpeak), blood lactate (La), rating of perceived exertion (RPE), and technical-tactical performance among soccer players across different bout durations (CB: continuous bout, MIB: medium intermittent bouts, and SIB: short intermittent bouts) and between male and female players during four-a-side (4vs4) small-sided games (SSGs) including goalkeepers.Methodssixteen female soccer players (age: 20.1 ± 0.5 years old) and sixteen professional male adults (age: 20.7 ± 0.7 years old) participated in the study. SSGs (4vs4) were performed in a CB: (1 × 12 min), and in an interval format: MIB: (2 × 6 min), and SIB: (3 × 4 min) with 2 min of passive recovery. PE was collected after each SSGs. The players’ heart rate (HR) was continuously measured, whereas ratings of perceived exertion (RPE) and, blood lactate concentration ([La]) were determined at the end of each SSGs. Technical-tactical performance were analyzed during each session of SSGs. Pitch dimensions were (length x width) (25 × 32 m), and relative space per players was 100 m2.ResultsFor female soccer players, medium intermittent bouts (MIB) elicited significantly higher perceived enjoyment (PE) compared to continuous bouts (CB) (p < 0.001) and short intermittent bouts (SIB) (p < 0.01). Conversely, for male soccer players, CB resulted in higher PE compared to MIB (p < 0.001) and SIB (p < 0.001). During CB and MIB, peak heart rate (PeakHR) and percentage of peak heart rate (%HRpeak) were significantly higher in female players compared to SIB (PeakHR: CB: p < 0.001; PeakHR: MIB: p < 0.01; %HRpeak: CB: p < 0.001; %HRpeak: MIB: p < 0.01). Blood lactate (La) and rating of perceived exertion (RPE) were significantly greater in CB compared to MIB (La: p < 0.001; RPE: p < 0.01) and SIB (La: p < 0.001; RPE: p < 0.001) for female players only. For male players, CB resulted in significantly higher PeakHR, %HRpeak, La, and RPE compared to MIB (peak HR: p < 0.01, dunb = 1.35; %HR: p < 0.01; La: p < 0.01; RPE: p < 0.01) and SIB (peak HR: p < 0,01; %HR: p < 0.01; RPE: md = 0.87, p < 0.05). Regarding technical-tactical performance, in female players, the % of successful passes, successful tackles, and successful duels were higher during SIB compared to CB (p < 0.01; p < 0.001; p < 0.001) and MIB compared to CB (p < 0.01; p < 0.001; p < 0.001), while ball loss was lower during SIB compared to CB (p < 0.001) and MIB compared to CB (p < 0.001). In male players, % of successful passes and tackles were higher during CB compared to MIB (p < 0.001 and p < 0.05) and SIB (p < 0.001 and p < 0.05), while CB had a lower % of ball loss compared to MIB (p < 0.01) and SIB (p < 0.001). There was no significant difference in the % of successful duels between the bouts for either gender.ConclusionThis study showed a difference in physical enjoyment between male and female soccer players depending on the bout duration of SSGs. For that, trainers should consider intermittent bouts for female soccer players and continuous bouts for male soccer players when designing SSGs-based training in order to significantly improve PE, training load, and technical-tactical performance.

How is variability in physiological responses to social stress related to punishment and reward sensitivities? Preliminary findings from the revised reinforcement sensitivity theory of personality perspective

ABSTRACTObjectiveAlthough personality traits are assumed to have biological/physiological foundations, research has yielded mixed evidence regarding the relationship between personality and physiological stress responses. Moreover, the field has often overlooked the contemporary neuroscience-based personality approach, known as the Reinforcement Sensitivity Theory (RST) of Personality, in stress research.MethodThe present study examined the relationship between the revised RST's personality dimensions and heart rate and skin conductance level (SCL) in response to the Trier Social Stress Test in a sample of 61 healthy university students.ResultsPiecewise latent growth curve analysis controlling for the participants’ current life stress, smoking use, and caffeine intake revealed that individuals with higher behavioral inhibition exhibited higher physiological reactivity, whereas those with high reward sensitivity showed smaller heart rate reactivity. The behavioral disengagement facet of the behavioral inhibition scale was associated with reduced sympathetic arousal during the stress task. Additionally, reward interest was associated with a larger recovery of SCL.ConclusionResults were generally in line with the revised theory. The study findings were discussed within the paradigm of the approach-avoidance conflict and highlighted the importance of reward sensitivity in stress resilience.

Water-use strategies and functional traits explain divergent linkages in physiological responses to simulated precipitation change

As a part of global climate change, precipitation patterns in arid regions will change significantly, and the different responses of desert plants to these changes will lead to alterations in community composition, thereby impacting ecosystem stability. Thus, understanding the mechanism underlying the associations among physiological response variables considering changing precipitation is crucial. Here, water-use strategies, functional traits, and physiological processes (e.g., photosynthesis (An), transpiration (Tr), leaf water potential (Ψl), stomatal conductance (gs), and soil respiration (Rs)) were measured in a precipitation experiment with two coexisting desert riparian species to determine how water-use strategies and functional traits operate together in generating physiological response mechanisms. The results showed that the two species exhibited divergent response pathways of physiological processes following rainfall events, although both were identified as isohydric plants with stringent stomatal regulation. For the shallow-rooted species N. sphaerocarpa, gs was sensitive to changes in both surface soil moisture (Swc) and Ψl, and Swc was the primary factor influencing Rs. These results were supported by the preference for shallow water and predominance of functional traits associated with drought avoidance. For the deep-rooted species R. soongorica, variations in gs were decoupled from Swc and directly influenced by enhanced Ψl, An was the main factor affecting Rs, while Ψl negatively affected Rs. These correlations could be attributed to the preference for deep water and functional traits associated with drought tolerance. These findings suggest that R. soongorica had a stronger tolerance to environmental water deficits and may expand extensively under drier climatic conditions in the future.

Analysing the effect of non-acoustical parameters on physiological response due to traffic noise exposure

Traffic noise, as an environmental stressor, impacts both auditory and non-auditory human health through a combination of acoustical and non-acoustical parameters. This study investigates the effects of sex, noise sensitivity, and cross-cultural differences on physiological stress responses to traffic noise exposure. A psychophysiological listening experiment was conducted with 60 participants from the United Kingdom and India to analyze the variation in physiological responses to the noise stimuli. The findings reveal significant gender differences in psychophysiological responses, with females exhibiting higher physiological arousal and potentially experiencing greater stress levels at moderate loudness levels compared to males. Moreover, individuals with high noise sensitivity displayed heightened stress levels and physiological arousal. Additionally, British participants exhibited higher physiological arousal, as indicated by increased skin conductance response parameters, compared to the Indian group. This suggests that exposure to Indian traffic noise, characterized by louder sounds and increased honking, leads to heightened stress levels among British participants. In conclusion, these findings contribute to our understanding of the relationship between traffic noise and physiological outcomes, shedding light on the influence of non-acoustical parameters. It also underscore the potential health implications of chronic noise exposure on human health.

White LED Lighting Increases the Root Productivity of Panax ginseng C. A. Meyer in a Hydroponic Cultivation System of a Plant Factory.

To identify effective light spectra for increasing the productivity of Panax ginseng, we conducted experiments in a controlled environment using a hydroponic cultivation system in a plant factory. We investigated the effect of single LEDs (red, blue, and yellow) and mixed LEDs (red + blue and red + blue + white). The relationships between four light spectra (red, blue, yellow, and white) and physiological responses (net photosynthetic rate, stomata conductance, transpiration rate, and intercellular CO2 partial pressure), as well as growth responses (shoot and root biomass), were analyzed using multivariate statistical analysis. Among the four physiological response variables, shoot biomass was not increased by any pathway, and root biomass was increased only by the intercellular CO2 partial pressure. Red and yellow light increased shoot biomass, whereas white light promoted an increase in the net photosynthetic rate and enhanced root biomass. In contrast, blue light was less effective than the other light spectra in increasing both shoot and root biomass. Therefore, red and yellow light are the most effective light spectra for increasing shoot biomass and white light is effective for increasing root biomass in a plant factory that uses artificial LED lighting. Furthermore, the intercellular CO2 partial pressure is an important physiological variable for increasing the root biomass of P. ginseng.

Validated computational models predict vagus nerve stimulation thresholds in preclinical animals and humans

Objective. We demonstrated how automated simulations to characterize electrical nerve thresholds, a recently published open-source software for modeling stimulation of peripheral nerves, can be applied to simulate accurately nerve responses to electrical stimulation. Approach. We simulated vagus nerve stimulation (VNS) for humans, pigs, and rats. We informed our models using histology from sample-specific or representative nerves, device design features (i.e. cuff, waveform), published material and tissue conductivities, and realistic fiber models. Main results. Despite large differences in nerve size, cuff geometry, and stimulation waveform, the models predicted accurate activation thresholds across species and myelinated fiber types. However, our C fiber model thresholds overestimated thresholds across pulse widths, suggesting that improved models of unmyelinated nerve fibers are needed. Our models of human VNS yielded accurate thresholds to activate laryngeal motor fibers and captured the inter-individual variability for both acute and chronic implants. For B fibers, our small-diameter fiber model underestimated threshold and saturation for pulse widths >0.25 ms. Our models of pig VNS consistently captured the range of in vivo thresholds across all measured nerve and physiological responses (i.e. heart rate, Aδ/B fibers, Aγ fibers, electromyography, and Aα fibers). In rats, our smallest diameter myelinated fibers accurately predicted fast fiber thresholds across short and intermediate pulse widths; slow unmyelinated fiber thresholds overestimated thresholds across shorter pulse widths, but there was overlap for pulse widths >0.3 ms. Significance. We elevated standards for models of peripheral nerve stimulation in populations of models across species, which enabled us to model accurately nerve responses, demonstrate that individual-specific differences in nerve morphology produce variability in neural and physiological responses, and predict mechanisms of VNS therapeutic and side effects.

Physiological responses, trunk posture, and work pace in commercial building cleaning in Washington State: An observational field study

Introduction: This study aimed to investigate whether work pace is a critical indicator for predicting a janitor’s risk of work-related musculoskeletal disorders (WMSDs). Method: Field measurements were obtained from commercial building janitors as well as the determination of work pace. Physiological responses collected were heart rate, energy expenditure (calories), activity level (METs), steps, trunk posture. Data were obtained using direct measurements, along with a time study, which was performed by shadowing 13 janitors in Washington State. The measured values were summarized descriptively, and five of the most common janitorial tasks were compared. The relationships between work pace and the physiological response variables were determined by calculating the Pearson product–moment correlation coefficients. Results: The highest average percent heart rate reserve (47.4%) was reported during restroom cleaning, while the highest activity and energy expenditure levels (3.6 METs and 217.1 calories/h) were reported for mopping. The top 90% of trunk flexion angles and the highest percentage of time in trunk flexion from 20° to 60° were recorded during restroom cleaning. Restroom cleaning showed the highest correlation between all the physiological response variables and work pace. In most of the tasks, a high work pace may have increased the degree and duration of severe trunk flexion. Conclusion: Overall, when several tasks were considered, the extent of physiological responses, trunk joint angles, and exposure time to awkward postures tended to increase with an increase in work pace. Practical Applications: This study showed the feasibility of using the work pace measured from time studies as a predictive indicator of WMSDs risks. Using this information, managers may compose a schedule that can minimize WMSDs risks while considering actual work pace deviations that may impact a janitor’s ability to complete assigned tasks properly within a shift.

Sex Differences in Blunt Traumatic Aortic Injury from the Aortic Trauma Foundation Global Registry

Trauma is the leading cause of death in people younger than 45 years, and blunt traumatic aortic injury (BTAI) is the second leading cause of death after blunt trauma. There have been reports on variations in physiological response to trauma between men and women, as well as sex/gender disparities in aortic disease outcomes, but there is a gap in the literature on sex differences in patients with traumatic aortic injury. The Aortic Trauma Foundation international prospective multicenter registry was used to examine sex differences in traumatic aortic injury characteristics, management, and outcomes from 2016 to 2022. Data were analyzed by contingency table, stratified and multivariable regression. There were 781 patients with BTAI and complete injury grade information, of whom 182 patients (23%) were female. The mean age was 43.4 ± 18 years, and women were significantly older than men (48 ± 18.6 vs 42.3 ± 17.6 years, P < .0001). A total of 464 patients (59%) underwent thoracic endovascular aortic repair with no significant difference between men (61%, 364 of 599) and women (55%, 100 of 182). Injury severity score and Glasgow coma scores did not differ between women and men. Women more often had pelvic fracture (41% vs 30%, P < .004), splenic injury (31% vs 23%, P < .05), renal injury (22% vs 14%, P < .02), sacral spine fracture (12% vs 6%, P < .02), and sternal fracture (17% vs 10%, P < .02), but these injury patterns were not associated with higher grade aortic injuries. There were no sex differences in the distribution of aortic injury grade. In-hospital mortality was 12%, and aortic-related mortality was 4% for the entire cohort, with no differences between men and women. The presence of sternal fracture appeared to predict higher aortic mortality in women (10% with sternal fracture vs 2% without, P = .05) but not in men (9% with sternal fracture vs 10% without P = .9). There is no difference in mortality between men and women with BTAI. Women with BTAI presented more frequently with intra-abdominal and pelvic injuries, and sternal fractures appear to predict a higher mortality in women with BTAI.

Respons Fisiologis Sapi Pedaging terhadap Pengabutan Air Menggunakan Sprinkler Water

Indonesia is facing the problem of low productivity of cattle. To increase the productivity of cattle producer, it can actually be done by relocating the cattle to the comfort zone by observing the physiological response. The purpose of this research is to evaluate the effects of misting cattle’s environment by using water sprinkler on the physiological response and the microclimate of the cattle’s shed. The design used was a paired T-test for physiological and microclimate response variables with 5 replications and a completely randomized design to determine the difference between body surface temperatures. The observations were conducted before water misting and after water misting. The results showed that treatment of misting water in the afternoon significantly decreased (P&lt;0.05) the variables of cage temperature, humidity, temperature humidity index, rectal temperature, respiratory rate, and heart rate. Water misting in the afternoon in cattle produced a good effect on all physiological response variables.&#x0D; &#x0D; Keywords: beef cattle, pen microclimate, physiological responses, water sprinkler

현대 생체시계 연구를 바탕으로 재조명한 &lt;황제내경 소문 사기조신대론&gt;의 계절에 따른 생활양식

Objectives In &lt;Hwangjenaegyeong Somun Sagijosindaelon&gt;, the climate change according to the four seasons is explained, and how to manage health by adjusting the lifestyle is recorded. Since the concepts of yin-yang and the four seasons are being re-examined in modern times with the discovery of biological clock genes, we attempted to scientifically reinterpret the classic text. Methods We reinterpreted the classic text and used keywords such as “circadian clock,” “circadian gene,” “seasonal variation,” “metabolism,” “environment,” and “climate” to search PubMed and Google Scholar for relevant articles. References in relevant articles were also considered. Results In mammals, the suprachiasmatic nucleus and the autonomic nervous system regulate seasonal variation in physiological responses in response to changes in the length of the external light cycle. Since most people now live in indoor environments with air conditioning and lighting, seasonal circadian rhythms have decreased in comparison to 100 years ago. Disrupting the circadian rhythm is equivalent to attacking the body from within by disrupting the order in the body. To restore and fine-tune the circadian rhythm and prevent serious diseases before the body's dysfunction becomes chronic, healthy eating, proper sleep, and adequate physical activity are required. Conclusions With the recent focus on global warming and environmental pollution, interest in climate change-related health issues is growing. Global cooperation will be required, and the effects of climate change on ecosystems and environments, as well as their impact on people's health, must be continuously monitored to protect the global environment and public health.

TSWIFT: Tower Spectrometer on Wheels for Investigating Frequent Timeseries for high-throughput phenotyping of vegetation physiology

BackgroundRemote sensing instruments enable high-throughput phenotyping of plant traits and stress resilience across scale. Spatial (handheld devices, towers, drones, airborne, and satellites) and temporal (continuous or intermittent) tradeoffs can enable or constrain plant science applications. Here, we describe the technical details of TSWIFT (Tower Spectrometer on Wheels for Investigating Frequent Timeseries), a mobile tower-based hyperspectral remote sensing system for continuous monitoring of spectral reflectance across visible-near infrared regions with the capacity to resolve solar-induced fluorescence (SIF).ResultsWe demonstrate potential applications for monitoring short-term (diurnal) and long-term (seasonal) variation of vegetation for high-throughput phenotyping applications. We deployed TSWIFT in a field experiment of 300 common bean genotypes in two treatments: control (irrigated) and drought (terminal drought). We evaluated the normalized difference vegetation index (NDVI), photochemical reflectance index (PRI), and SIF, as well as the coefficient of variation (CV) across the visible-near infrared spectral range (400 to 900 nm). NDVI tracked structural variation early in the growing season, following initial plant growth and development. PRI and SIF were more dynamic, exhibiting variation diurnally and seasonally, enabling quantification of genotypic variation in physiological response to drought conditions. Beyond vegetation indices, CV of hyperspectral reflectance showed the most variability across genotypes, treatment, and time in the visible and red-edge spectral regions.ConclusionsTSWIFT enables continuous and automated monitoring of hyperspectral reflectance for assessing variation in plant structure and function at high spatial and temporal resolutions for high-throughput phenotyping. Mobile, tower-based systems like this can provide short- and long-term datasets to assess genotypic and/or management responses to the environment, and ultimately enable the spectral prediction of resource-use efficiency, stress resilience, productivity and yield.

Plant water‐use strategies predict restoration success across degraded drylands

Abstract Plant strategies for coping with water limitation are likely to mediate restoration outcomes in degraded dryland ecosystems. Trade‐offs in traits related to water acquisition and use can intensify in more arid environments, making their effects on dryland restoration success even more salient. However, isolating the effects of drought responses from those of other environmental factors, as well as identifying the specific drought resistance traits that influence restoration success, can be difficult. In the present study, we couple a controlled dry‐down experiment with a cross‐site restoration field trial of out‐planted seedlings (RestoreNet) using a suite of dryland herbaceous plant species from the same seed sources. We quantified interspecific variation in physiological responses to drought, specifically reductions in stomatal conductance (gs) and stem water potential (SWP), by comparing well‐watered control plants to those experiencing decreasing soil moisture. Drought responses of SWP and gs varied independently among species, but both were related to survival in the cross‐site restoration field trial when effect sizes were aggregated across all sites. Responses were consistent with acquisitive water‐use strategies resulting in greater success, where species with greater declines in SWP or weaker declines in gs under drought had greater survival. The correlation between SWP drought response and survival also intensified in sites with lower accumulated precipitation following restoration. Differences among functional groups revealed two different paths to restoration success: forbs that maintain high gs and narrow safety margins to maximize exploitation of moisture pulses before going into drought dormancy, or C4 grasses that maintain efficient water uptake in drying soils while risking cavitation. C3 grass species varied between these two strategies. Synthesis and applications. Taken together, the results of this study and others conducted at RestoreNet sites indicate that while a diversity of physiological responses to drought may exist in dryland plant communities, successfully restoring herbaceous species through out‐planting in degraded conditions is likely to be achieved with species that maximize water uptake via one of two strategies, with tolerance of low SWP being particularly important in the most arid settings.

IAA-decorated CuO nanocarriers significantly improve Chickpea growth by increasing antioxidative activities.

Plant growth regulators tagged on metallic oxide nanoparticles (NPs) may function as nanofertilizers with reduced toxicity of NPs. CuO NPs were synthesized to function as nanocarriers of Indole-3-acetic acid (IAA). Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed 30.4nm size of NPs and sheet-like structure, respectively, of CuO-IAA NPs. Fourier-transform infrared spectroscopy (FTIR) confirmed CuO-IAA formation. IAA-decorated CuO NPs enhanced the physiological parameters of Chickpea plants, i.e., root length, shoot length, and biomass compared to naked CuO NPs. The variation in physiological response was due to change of phytochemical contents in plants. Phenolic content increased up to 17.98 and 18.13 µgGAE/mg DW at 20 and 40mg/L of CuO-IAA NPs, respectively. However, significant decrease in antioxidant enzymes' activity was recorded compared to control. Presence of CuO-IAA NPs increased the reducing potential of plants at higher concentration of NPs, while decrease in total antioxidant response was observed. This study concludes that IAA conjugation to CuO NPs reduces toxicity of NPs. Furthermore, NPs can be explored as nanocarriers for plant modulators and slow release in future studies.

Critical power: a paradigm-shift for benchmarking exercise testing and prescription.

Inherent in the work of Collins et al. (2022) is the notion that prescription of exercise intensity relative to CP (and also the gas exchange threshold, GET; see Lansley et al., 2011) will reduce the variability in physiological responses and exercise tolerance. And that is precisely the hypothesis tested by Meyler et al. (2023) in this issue of Experimental Physiology. Specifically, in healthy men and women who completed multiple exhausting cycling tests (graded exercise test, series of constant-power tests) to define GET, CP and W′, these parameters and also V ̇ O 2 max ${\dot V_{{{\rm{O}}_2}\max }}$ (i.e., at defined percentages of V ̇ O 2 max ${\dot V_{{{\rm{O}}_2}\max }}$ ) were utilized to anchor separate moderate- (MOD), heavy- and severe-intensity criterion exercise bouts. Subsequently, two series of MOD, HEAVY and SEVERE exercise bouts, the latter as high intensity 5 × 3 min intervals, were prescribed ‘traditionally’ (TRAD) based upon V ̇ O 2 max ${\dot V_{{{\rm{O}}_2}\max }}$ (i.e., 50%, 77% and 85%) or using the GET and CP parameters (THR; MOD: 30 min at 90% GET; HEAVY: 20 min at 50%∆ (midway between GET and CP); and SEVERE: at 110% CP). Primary results supported the hypothesis for HEAVY and SEVERE exercise with respect to reduced variability of work rates for THR versus TRAD. Crucially, whereas some subjects for HEAVY–TRAD exercised in the severe-intensity domain with the attendant V ̇ O 2 ${\dot V_{{{\rm{O}}_2}}}$ and [lactate] consequences – and 70% of them became exhausted for TRAD versus 0% for THR – this was not the case for HEAVY–THR. For the SEVERE trials neither peak nor mean V ̇ O 2 ${\dot V_{{{\rm{O}}_2}}}$ and heart rate variability were different between TRAD and THR, but peak and mean [lactate] variability were lower for THR, as was percentage W′ depletion. The scientific literature is, unfortunately, replete with examples of otherwise very well designed studies where the investigators have chosen to ‘normalize’ heavy exercise intensity by exercising their participants at either a fixed % V ̇ O 2 max ${\dot V_{{{\rm{O}}_2}\max }}$ , often 75% or 80%, or at 50%∆ between GET and V ̇ O 2 max ${\dot V_{{{\rm{O}}_2}\max }}$ . So doing has resulted in highly divergent physiological responses characteristic of some participants exercising in the heavy (i.e., stable V ̇ O 2 ${\dot V_{{{\rm{O}}_2}}}$ and [lactate] profiles, Tlim >> 30 min) and others in the severe (i.e., V ̇ O 2 max ${\dot V_{{{\rm{O}}_2}\max }}$ achieved, rising [lactate], exhaustion < 20 min) exercise domains. Meyler et al. (2023) demonstrate that prescribing exercise relative to CP can prevent this occurrence and, even for supra-CP exercise, reduce inter-subject response variability for key physiological indices. This rationale has also been presented, on a more theoretical level, for normalizing the assessment of exercise for therapeutic efficacy across patient populations, especially chronic obstructive pulmonary disease (Whipp & Ward, 2009). Although beyond the limits of the measurements in Meyler et al. (2023), it is also important to note that, by registering severe-intensity exercise bouts to CP and thereby lowering inter-subject variability for W′ depletion, it would be expected that greater homogeneity would be achieved across participants for intramyocyte perturbations (e.g., ∆[PCr], [Pi], [ADPfree], [H+], [glycogen]; Jones et al., 2008) in addition to, of course, improved ability to predict exercise tolerance. The implications and therefore putative impact of the findings of Meyler et al. (2023) are substantial and reach across the preserves of exercise science to better inform, prescribe and evaluate athletic training regimens, improve the assessment of the efficacy of therapeutic interventions and, of course, help resolve the mechanistic bases for exercise intolerance itself. Both authors have read and approved the final version of this manuscript and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All persons designated as authors qualify for authorship, and all those who qualify for authorship are listed. None declared. None.

Variability in exercise tolerance and physiological responses to exercise prescribed relative to physiological thresholds and to maximum oxygen uptake.

What is the central question of this study? Does prescribing exercise intensity using physiological thresholds create a more homogeneous exercise stimulusthanusing traditional intensity anchors? What is the main finding and its importance? Prescribing exercise using physiological thresholds, notably critical power, reduced the variability in exercise tolerance and acute metabolic responses. At higher intensities, approaching or exceeding the transition from heavy to severe intensity exercise, the imprecision of using fixed % as an intensity anchor becomes amplified. The objective of this study was to determine whether the variability in exercise tolerance and physiological responses is lower when exercise is prescribed relative to physiological thresholds (THR) compared to traditional intensity anchors (TRAD). Ten individuals completed a series of maximal exercise tests and a series of moderate (MOD), heavy (HVY) and severe intensity (HIIT) exercise bouts prescribed using THR intensity anchors (critical power and gas exchange threshold) and TRAD intensity anchors (maximum oxygen uptake; ). There were no differences in exercise tolerance or acute response variability between MODTHR and MODTRAD . All individuals completed HVYTHR but only 30% completed HVYTRAD . Compared to HVYTHR , where work rates were all below critical power, work rates in HVYTRAD exceeded critical power in 70% of individuals. There was, however, no difference in acute response variability between HVYTHR and HVYTRAD . All individuals completed HIITTHR but only 20% completed HIITTRAD . The variability in peak (F=0.274) and average (F=0.318) blood lactate responses was lower in HIITTHR compared to HIITTRAD . The variability in W' depletion (the finite work capacity above critical power) after the final interval bout was lower in HIITTHR compared to HIITTRAD (F=0.305). Using physiological thresholds to prescribe exercise intensity reduced the heterogeneity in exercise tolerance and physiological responses to exercise spanning the boundary between the heavy and severe intensity domains. To increase the precision of exercise intensity prescription, it is recommended that, where possible, physiological thresholds are used in place of .

Thermal sensitivities of respiration and protein synthesis differ among larval families of the Pacific oyster, Crassostrea gigas.

Understanding the mechanisms of biological responses to environmental change is a central theme in comparative and evolutionary physiology. Here, we analyzed variation in physiological responses to temperature, using 21 full-sibling larval families of the Pacific oyster, Crassostrea gigas. Pedigrees were confirmed with genetic markers for adult broodstock obtained from our breeding program. From these 21 larval families, 41 determinations of thermal sensitivity (Q10 values) were assayed for larvae of different sizes. For respiration, thermal sensitivity was consistent within a larval family during growth, but showed significant differences among families. Different Q10 values were evident among 21 larval families, with family accounting for 87% of variation. Specifically, four larval families maintained an increased thermal sensitivity for respiration (Q10 of 3). This physiology would confer resilience to rising temperature by matching the increased energy demand of protein synthesis (Q10 of 3 previously reported). For protein synthesis, differences in Q10 values were also observed. Notably, a family was identified that had a decreased thermal sensitivity for protein synthesis (Q10 of 1.7 cf. Q10 of 3 for other families), conferring an optimal energy allocation with rising temperature. Different thermal sensitivities across families for respiration (energy supply) and protein synthesis (energy demand) were integrated into models of energy allocation at the whole-organism level. The outcome of these analyses provides insights into the physiological bases of optimal energy allocation with rising temperature. These transgenerational (egg-to-egg) experiments highlight approaches to dissect components of phenotypic variance to address long-standing questions of genetic adaptation and physiological resilience to environmental change.

Intersubject Variability in Cerebrovascular Hemodynamics and Systemic Physiology during a Verbal Fluency Task under Colored Light Exposure: Clustering of Subjects by Unsupervised Machine Learning.

There is large intersubject variability in cerebrovascular hemodynamic and systemic physiological responses induced by a verbal fluency task (VFT) under colored light exposure (CLE). We hypothesized that machine learning would enable us to classify the response patterns and provide new insights into the common response patterns between subjects. In total, 32 healthy subjects (15 men and 17 women, age: 25.5 ± 4.3 years) were exposed to two different light colors (red vs. blue) in a randomized cross-over study design for 9 min while performing a VFT. We used the systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS) approach to measure cerebrovascular hemodynamics and oxygenation at the prefrontal cortex (PFC) and visual cortex (VC) concurrently with systemic physiological parameters. We found that subjects were suitably classified by unsupervised machine learning into different groups according to the changes in the following parameters: end-tidal carbon dioxide, arterial oxygen saturation, skin conductance, oxygenated hemoglobin in the VC, and deoxygenated hemoglobin in the PFC. With hard clustering methods, three and five different groups of subjects were found for the blue and red light exposure, respectively. Our results highlight the fact that humans show specific reactivity types to the CLE-VFT experimental paradigm.