Intensity Cycling Research Articles

Moderate-to-vigorous intensity cycling exercise immediately after visual learning enhances delayed recognition memory performance

A single bout of acute aerobic exercise has been shown to improve long-term memory, though it is unclear if exercise before learning or after learning is optimal for memory enhancement. Although some research has demonstrated that exercise before learning is ideal, investigations have consistently shown that acute arousal post-learning is a powerful memory enhancer. Therefore, the purpose of this investigation was to compare the effects of self-perceived hard cycling before or after learning on recognition memory for emotional and neutral images, and examine the relationship between central noradrenergic activity and memory performance. Seventy-two males and females (18–35 years of age) participated in this between-subjects study. Participants were randomly assigned to one of the following groups: exercise before learning, exercise after learning, and control. Participants in the exercise groups engaged in 20 min of cycling at a rating of perceived exertion (RPE) of 15 (“hard”) on the Borg RPE scale before or after viewing a series of 90 pleasant, unpleasant, and neutral images (30 each). Participants in the control group engaged in no exercise before or after image viewing. At several time points throughout the experiment, saliva was collected to measure salivary alpha amylase (sAA), a marker of central noradrenergic activity. One-week later, recognition memory was assessed where participants viewed 180 images (90 new) and had to identify which images were previously viewed. Participants in the exercise after learning group had significantly higher recognition memory compared to the control group, but this was not seen with exercise before learning. sAA was not correlated with memory in any group, though it did increase during exercise. These results demonstrate that acute self-perceived hard cycling post-learning, but not pre-learning, improves recognition memory, though this was unrelated to the exercise-induced increase in central noradrenergic activity as measured in saliva.

The effect of sex and estrus cycle stage on optogenetic spreading depression induced migraine-like pain phenotypes

BackgroundMigraine is more prevalent in females, raising the possibility that sex and gonadal hormones modulate migraine. We recently demonstrated that minimally invasive optogenetic spreading depolarization (opto-SD) elicits robust periorbital allodynia. The objective of this study was to test the hypothesis that opto-SD induced migraine-like pain behavior is worse in females and varies during the estrus cycle.MethodsSingle or repeated opto-SDs were induced in male and female adult Thy1-ChR2-YFP transgenic mice. Von Frey monofilaments were used to test periorbital mechanical allodynia. Mouse grimace was also examined under increasing light intensity to quantify spontaneous discomfort and light-aversive behavior. Vaginal smears were obtained for estrus cycle staging at the end of behavioral testing.ResultsA multi-variable regression analysis was performed using a male and female cohort to test the effect of independent variables on periorbital allodynia. Opto-SD predicted lower periorbital thresholds as compared with sham stimulation (p < 0.0001). Additionally, female sex predicted lower periorbital thresholds compared with males (p = 0.011). There were significant interactions between opto-SD and time (interaction p = 0.030) as animals tended to recover from opto-SD allodynia over time, and between sex and time (p = 0.020) as females tended to take longer to recover. Proestrus, estrus (PE) and metestrus, diestrus (MD) stages were combined to represent high versus low circulating estradiol relative to progesterone, respectively. Multi-variable regression revealed an effect of estrus cycle (p = 0.015) on periorbital thresholds. In the sham group, PE had lower thresholds than MD. However, there was no interaction between opto-SD and the estrus cycle (p = 0.364). Grimace scores were also examined at incremental light intensities. There was an effect of opto-SD (p < 0.0001), light intensity (p = 0.001) and estrus cycle (p = 0.024) on grimace without interaction among them (three-way ANOVA).ConclusionsFemale sex and estrus stages with high circulating estradiol relative to progesterone lower trigeminal pain thresholds and augment photosensitivity. In females, opto-SD increased pain behavior and photosensitivity irrespective of the estrus stage.Graphical

The effects of intensity, spectral purity and duty cycle on red light-induced hyperopia in tree shrews.

There have recently been several clinical studies suggesting that brief periods of exposure to red light (repeated low-level red light, 'RLRL') may produce a dramatic anti-myopia effect, calling for further investigations into its therapeutic parameters. Unfortunately, many experimental species used in refractive studies develop myopia in response to this wavelength. Tree shrews are the only animal model other than rhesus monkeys that consistently exhibit hyperopic responses to ambient red light. Here, tree shrews were used to study the influence of the spectral purity, duty cycle and intensity of red light on its anti-myopic effect. Juvenile tree shrews (Tupaia belangeri) were raised from 24 to 35 days after eye opening under ambient lighting that was: standard white colony fluorescent light; pure narrow band red light of either 600, 50-100 or 5 lux; red light that was diluted with 10% white light (by lux) or 50% white and 2 s of pure red light that alternated with 2 s of pure white light (50% duty cycle). Refractive measures were taken with a NIDEK ARK-700 autorefractor and axial dimensions with a LenStar LS-900 Axial Biometer. The pro-hyperopia effect of ambient red light was greatly reduced by even small amounts of concurrent white light 'contamination', but remained robust if 2-s periods of pure white light alternated with 2 s of red. Finally, the hyperopic effect of red light was maintained at reduced luminance levels in the 50-100 lux range and only failed at 5 lux. These results have implications for understanding the mechanisms by which ambient red light affects refractive development, and possibly also for clinical therapies using RLRL. Nevertheless, it remains to be determined if the mechanism of the current clinical RLRL therapy is the same as that operating on tree shrews in ambient red light.

The Role of Density Currents and Gravity Waves in the Offshore Propagation of Convection over Sumatra

Abstract The Maritime Continent experiences some of the world’s most severe convective rainfall, with an intense diurnal cycle. A key feature is offshore propagation of convection overnight, having peaked over land during the evening. Existing hypotheses suggest this propagation is due to the nocturnal land breeze and environmental wind causing low-level convergence; and/or gravity waves triggering convection as they propagate. We use a convection-permitting configuration of the Met Office Unified Model over Sumatra to test these hypotheses, verifying against observations from the Japanese Years of the Maritime Continent field campaign. In selected case studies there is an organized squall line propagating with the land-breeze density current, possibly reinforced by convective cold pools, at ∼3 m s−1 to around 150–300 km offshore. Propagation at these speeds is also seen in a composite mean diurnal cycle. The density current is verified by observations, with offshore low-level wind and virtual potential temperature showing a rapid decrease consistent with a density current front, accompanied by rainfall. Gravity waves are identified in the model with a typical phase speed of 16 m s−1. They trigger isolated cells of convection, usually farther offshore and with much weaker precipitation than the squall line. Occasionally, the isolated convection may deepen and the rainfall intensify, if the gravity wave interacts with a substantial preexisting perturbation such as shallow cloud. The localized convection triggered by gravity waves does not generally propagate at the wave’s own speed, but this phenomenon may appear as propagation along a wave trajectory in a composite that averages over many days of the diurnal cycle. Significance Statement The intense convection experienced by the Maritime Continent causes high-impact weather in the form of heavy precipitation, which can trigger floods and landslides, endangering human life and infrastructure. The geography of the region, with many islands with complex coastlines and orography, means that the spatial and temporal distributions of convection are difficult to predict. This presents challenges for operational forecasters in the region and introduces biases in weather and climate models, which may propagate globally. A key feature of the convection is its diurnal cycle and associated propagation offshore overnight from the islands. Although this phenomenon has been often investigated, there is no strong consensus in the literature on the mechanism or combination of mechanisms responsible. Improving our knowledge of these mechanisms and how they are represented in a convection-permitting model will assist forecasters in understanding how and when the propagation of intense convective storms occurs, and allow model developers to improve biases in numerical weather prediction and climate models.

Metabolic Cost of a Proposed NMES Spaceflight Countermeasure Compared to Walking in Active Adults.

INTRODUCTION: Astronauts exercise to reduce microgravity-induced bone loss, but the resultant skeletal loading may not be sufficient to reduce fracture risk on an extended Mars mission. Adding additional exercise increases the risk of a negative caloric balance. Neuromuscular electrical stimulation (NMES) induces involuntary muscle contractions, which load the skeleton. The metabolic cost of NMES is not fully understood. On Earth, walking is a common source of skeletal loading. If the metabolic cost of NMES were equal to or less than walking, it could offer a low metabolic cost option for increasing skeletal loading.METHODS:We measured the oxygen consumed and carbon dioxide produced from 10 subjects during 5-min bouts of walking at 2 mph, 3 mph, and 2 mph on a 6° incline, and of NMES to the legs at duty cycles of 1 s on and 5 s, 4 s, or 3 s off. Metabolic cost was calculated using the Brockway equation and the percent increase above resting for each NMES bout was compared to walking.RESULTS: Metabolic cost increased 64.9 ± 52.8% from rest in the most intense NMES duty cycle (1 s/3 s) and 120.4 ± 26.5%, 189.3 ± 59.5%, 281.7 ± 66.8%, for the 2 mph, 3 mph, and incline walking, respectively. The metabolic cost did not differ significantly between the three NMES duty cycles.DISCUSSION: The increase in metabolic cost of the fastest NMES bout was less than that of the slowest walk, indicating that numerous NMES bouts offer a way to increase skeletal loading at a modest metabolic cost. This might allow for more daily skeletal loading cycles, potentially further reducing bone loss.Abitante TJ, Alemi MM, Newman DJ, Duda KR. Metabolic cost of a proposed NMES spaceflight countermeasure compared to walking in active adults. Aerosp Med Hum Perform. 2023; 94(7):523-531.

Effect of Light-Intensity Cycle Ergometer Aerobic Exercise on 2-Min Walking Test Distance and Maximum Oxygen Uptake in Myasthenia Gravis Patients: A Randomized Controlled Trial

Introduction: Fatigue and impaired functional capacity are more likely to be observed with myasthenia gravis (MG). MG prevalence in the Indonesian population is still limited. MG can benefit from participating in aerobic exercise without causing a decline in function, but relatively few exercise training studies have been conducted in this group of patients. This study analyzed how light-intensity cycle ergometer aerobic exercise influences functional and aerobic capacity in MG. Methods: An 8-week randomized controlled trial using a light-intensity cycle ergometer for aerobic exercise three times a week was carried out on adult patients with MG Foundation of America Class I-IIa, and adult patients. Eighteen MG patients were randomly assigned to the intervention or control group (standard exercise training). Two-min walking tests (2MWTs) distance and maximum oxygen uptake (VO2Max) were measured before and after the 8-week intervention. VO2Max was calculated from the 2MWT formula. A t-test was used to compare 2MWT distance and VO2Max within and between groups with a significance level of P &lt; 0.05. Results: Light intensity cycle ergometer aerobic exercise significantly improved the functional and aerobic capacity in the intervention group at 8 weeks (2MWT distance P = 0.001 and VO2Max P = 0.001) but not in the control group (P = 0.523 and P = 0.575, respectively). Substantial changes were also found between groups in both 2MWT distances (P = 0.002; effect size = 1.75) and VO2Max (P = 0.001; effect size = 1.81) pre- and post-test. Conclusion: Eight weeks of light-intensity cycle ergometer aerobic exercise improves the functional and aerobic capacity of adult MG patients.

Intensive cycles of neoadjuvant camrelizumab combined with chemotherapy in locally advanced esophageal squamous cell carcinoma: a single-arm, phase II trial

BackgroundTwo cycles of neoadjuvant PD-1 blockade plus chemotherapy induced favorable pathological response and tolerant toxicity in patients with locally advanced esophageal squamous cell carcinoma (ESCC). However, approximately 25% of patients relapsed within 1 year after surgery, indicating that a short course of treatment may not be sufficient. Therefore, exploring the effects of intensive treatment is needed for optimal clinical outcomes.MethodsLocally advanced ESCC patients were administered three cycles of camrelizumab plus nab-paclitaxel and capecitabine, followed by thoracoscopic esophagectomy. The primary endpoint was pathologic response. Secondary endpoints included safety, feasibility, radiologic response, survival outcomes, and immunologic/genomic correlates of efficacy.ResultsForty-seven patients were enrolled in the study. Forty-two patients received surgery, and R0 resection was achieved in all cases. The complete and major pathological response rates were 33.3% and 64.3%, respectively, and the objective response rate was 80.0%. Three cycles of treatment significantly improved T down-staging compared to two cycles (P = 0.03). The most common treatment-related adverse events were grades 1–2, and no surgical delay was reported. With a median follow-up of 24.3 months, the 1-year disease-free survival and overall survival rates were both 97.6%, and the 2-year disease-free survival and overall survival rates were 92.3% and 97.6%, respectively. Three patients experienced disease recurrence or metastasis ranging from 12.5 to 25.8 months after surgery, and one patient died 6 months after surgery due to cardiovascular disease. Neither programmed death-ligand 1 expression nor tumor mutational burden was associated with pathological response. An increased infiltration of CD56dim natural killer cells in the pretreatment tumor was correlated with better pathological response in the primary tumor.ConclusionsIt seems probable that intensive cycles of neoadjuvant camrelizumab plus nab-paclitaxel and capecitabine increased tumor regression and improved survival outcomes. Randomized controlled trials with larger sample sizes and longer follow-up periods are needed to validate these findings.Trial registration Chinese Clinical Trial Registry, ChiCTR2000029807, Registered February 14, 2020, https://www.chictr.org.cn/showproj.aspx?proj=49459.

Trophic ecology of Angolan cold-water coral reefs (SE Atlantic) based on stable isotope analyses

Cold-water coral (CWC) reefs of the Angolan margin (SE Atlantic) are dominated by Desmophyllum pertusum and support a diverse community of associated fauna, despite hypoxic conditions. In this study, we use carbon and nitrogen stable isotope analyses (δ13C and δ15N) to decipher the trophic network of this relatively unknown CWC province. Although fresh phytodetritus is available to the reef, δ15N signatures indicate that CWCs (12.90 ± 1.00 ‰) sit two trophic levels above Suspended Particulate Organic Matter (SPOM) (4.23 ± 1.64 ‰) suggesting that CWCs are highly reliant on an intermediate food source, which may be zooplankton. Echinoderms and the polychaete Eunice norvegica occupy the same trophic guild, with high δ13C signatures (-14.00 ± 1.08 ‰) pointing to a predatory feeding behavior on CWCs and sponges, although detrital feeding on 13C enriched particles might also be important for this group. Sponges presented the highest δ15N values (20.20 ± 1.87 ‰), which could be due to the role of the sponge holobiont and bacterial food in driving intense nitrogen cycling processes in sponges’ tissue, helping to cope with the hypoxic conditions of the reef. Our study provides first insights to understand trophic interactions of CWC reefs under low-oxygen conditions.

A Cycle Slip Detection and Repair Method Based on Inertial Aiding for BDS Triple-Frequency Signals

Cycle slip detection and repair is a prerequisite to obtain high-precision positioning based on a carrier phase. Traditional triple-frequency pseudorange and phase combination algorithm are highly sensitive to the pseudorange observation accuracy. To solve the problem, a cycle slip detection and repair algorithm based on inertial aiding for a BeiDou navigation satellite system (BDS) triple-frequency signal is proposed. To enhance the robustness, the INS-aided cycle slip detection model with double-differenced observations is derived. Then, the geometry-free phase combination is united to detect the insensitive cycle slip, and the optimal coefficient combination is selected. Furthermore, the L2-norm minimum principle is used to search and confirm the cycle slip repair value. To correct the INS error accumulated over time, the extended Kalman filter based on the BDS/INS tightly coupled system is established. The vehicular experiment is conducted to evaluate the performance of the proposed algorithm from a few aspects. The results indicate that the proposed algorithm can reliably detect and repair all cycle slips that occur in one cycle, including the small and insensitive cycle slips as well as the intensive and continuous cycle slips. Additionally, in signal-challenged environments, the cycle slips occurring 14 s after a satellite signal outage can be correctly detected and repaired.

Emotional processing and positive affect after acute exercise in healthy older adults.

The well-elucidated improvement of mood immediately after exercise in older adults presumably involves adaptations in emotion-processing brain networks. However, little is known about effects of acute exercise on appetitive and aversive emotion-related network recruitment in older adults. The purpose of this study was to determine the effect of acute exercise, compared to a seated rest control condition, on pleasant and unpleasant emotion-related regional activation in healthy older adults. Functional MRI data were acquired from 32 active older adults during blocked presentations of pleasant, neutral and unpleasant images from the International Affective Pictures System. fMRI data were collected after participants completed 30 min of moderate to vigorous intensity cycling or seated rest, performed in a counterbalanced order across separate days in a within-subject design. The findings suggest three ways that emotional processing in the brain may be different immediately after exercise (relative to immediately after rest): First, reduced demands on emotional regulation during pleasant emotional processing as indicated by lower precuneus activation for pleasant stimuli; second, reduced processing of negative emotional stimuli in visual association areas as indicated by lower activation for unpleasant stimuli in the bilateral fusiform and ITG; third, an increased recruitment in activation associated with regulating/inhibiting unpleasant emotional processing in the bilateral medial superior frontal gyrus (dorsomedial prefrontal cortex), angular gyri, supramarginal gyri, left cerebellar crus I/II and a portion of right dorsolateral prefrontal cortex. Overall, these findings support that acute exercise in active older adults alters activation in key emotional processing and regulating brain regions.

Why everything is connected to everything else

In Earth surface systems (ESS), everything is connected to everything else, an aphorism often called the First Law of Ecology and of geography. Such linkages are not always direct and unmediated, but many ESS, represented as networks of interacting components, attain or approach full, direct connectivity among components. The question is how and why this happens at the system or network scale. The crowded landscape concept dictates that linkages and connections among ESS components are inevitable. The connection selection concept holds that the linkages among components are (often) advantageous to the network and are selected for, and thereby preserved and enhanced. These network advantages are illustrated via algebraic graph theory. For a given number of components in an ESS, as the number of links or connections increases, spectral radius, graph energy, and algebraic connectivity increase. While the advantages (if any) of increased complexity are unclear, higher spectral radii are directly correlated with higher graph energy. The greater graph energy is associated with more intense feedback in the system, and tighter coupling among components. This in turn reflects advantageous properties of more intense cycling of water, nutrients, and minerals, as well as multiple potential degrees of freedom for individual components to respond to changes. The increase of algebraic connectivity reflects a greater ability or tendency for the network to respond to changes in concert.

Illuminance-tuned collective motion in fish

We experimentally investigate the role of illumination on the collective dynamics of a large school (ca. 50 individuals) of Hemigrammus rhodostomus. The structure of the group, defined using two order parameters, is quantified while progressively altering the visual range of the fish through controlled cycles of ambient light intensity. We show that, at low light levels, the individuals within the group are unable to form a cohesive group, while at higher illuminance the degree of alignment of the school correlates with the light intensity. When increasing the illuminance, the school structure is successively characterized by a polarized state followed by a highly regular and stable rotational configuration (milling). Our study shows that vision is necessary to achieve cohesive collective motion for free swimming fish schools, while the short-range lateral line sensing is insufficient in this situation. The present experiment therefore provides new insights into the interaction mechanisms that govern the emergence and intensity of collective motion in biological systems.

Seasonal controls on isolated convective storm drafts, precipitation intensity, and life cycle as observed during GoAmazon2014/5

Abstract. Isolated deep convective cloud life cycle and seasonal changes in storm properties are observed for daytime events during the US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Green Ocean Amazon Experiment (GoAmazon2014/5) campaign to understand controls on storm behavior. Storm life cycles are documented using surveillance radar from initiation through maturity and dissipation. Vertical air velocity estimates are obtained from radar wind profiler overpasses, with the storm environment informed by radiosondes. Dry-season storm conditions favored reduced morning shallow cloud coverage and larger low-level convective available potential energy (CAPE) than wet-season counterparts. The typical dry-season storm reached its peak intensity and size earlier in its life cycle compared with wet-season cells. These cells exhibited updrafts in core precipitation regions (Z&gt;35 dBZ) to above the melting level as well as persistent downdrafts aloft within precipitation adjacent to their cores. Moreover, dry-season cells recorded more intense updrafts to earlier life cycle stages as well as a higher incidence of strong updrafts (i.e., &gt;5 m s−1) at low levels. In contrast, wet-season storms were longer-lived and featured a higher incidence of moderate (i.e., 2–5 m s−1) updrafts aloft. These storms also favored a shift in their most intense properties to later life cycle stages. Strong downdrafts were less frequent within wet-season cells aloft, indicating a potential systematic difference in draft behaviors, as linked to graupel loading and other factors between the seasons. Results from a stochastic parcel model suggest that dry-season cells may expect stronger updrafts at low levels because of larger low-level CAPE in the dry season. Wet-season cells anticipate strong updrafts aloft because of larger free-tropospheric relative humidity and reduced entrainment-driven dilution. Enhanced dry-season downdrafts are partially attributed to increased evaporation, dry-air entrainment mixing, and negative buoyancy in regions adjacent to sampled dry-season cores.

The Relationship between Model Biases in East Asian Summer Monsoon Rainfall and Land Evaporation

The East Asian Summer Monsoon (EASM) provides the majority of annual rainfall to countries in East Asia. Although state-of-the-art models broadly project increased EASM rainfall, the spread of projections is large and simulations of present-day rainfall show significant climatological biases. Systematic evapotranspiration biases occur locally over East Asia, and globally over land, in simulations both with and without a coupled ocean. This study explores the relationship between evapotranspiration and EASM precipitation biases. First, idealized model simulations are presented in which the parameterization of land evaporation is modified, while sea surface temperature is fixed. The results suggest a feedback whereby excessive evapotranspiration over East Asia results in cooling of land, a weakened monsoon low, and a shift of rainfall from the Philippine Sea to China, further fueling evapotranspiration. Cross-model regressions against evapotranspiration over China indicate a similar pattern of behavior in Atmospheric Model Intercomparison Project (AMIP) simulations. Possible causes of this pattern are investigated. The feedback is not explained by an overly intense global hydrological cycle or by differences in radiative processes. Analysis of land-only simulations indicates that evapotranspiration biases are present even when models are forced with prescribed rainfall. These are strengthened when coupled to the atmosphere, suggesting a role for land-model errors in driving atmospheric biases. Coupled atmosphere-ocean models are shown to have similar evapotranspiration biases to those in AMIP over China, but different precipitation biases, including a northward shift in the ITCZ over the Pacific and Atlantic Oceans.

Can exercise prevent the age‐related decline in adaptive homeostasis? Evidence across organisms and tissues

Can exercise prevent the age‐related decline in adaptive homeostasis? Evidence across organisms and tissues

MiRNA expression in human skeletal muscle following an acute bout of moderate intensity cycle ergometry exercise

Exercise is a potent stimulus that drives both physical and metabolic adaptations, with novel emerging techniques permitting investigation of their molecular mechanisms. The purpose of this study was to utilize small RNA sequencing to determine differentially expressed miRNAs in skeletal muscle of lean humans before and following a single bout of moderate cycling exercise. Total RNA was extracted (RNeasy fibrous tissue kit, Qaigen) from vastus lateralis biopsy samples collected before and after (1.5 hours) a single bout of moderate intensity (75% VO2peak) cycle ergometry exercise perform by 5 unaccustomed volunteer adults (age = 24±3 yrs, BMI = 23.7±3.2). Small RNA library was prepared using the NEXTFLEX® Small RNA-Seq Kit v3. Samples were run on an SP100 flow cell with 51bp paired end reads at TGEN Collaborative Sequencing Center (Phoenix, AZ). Fastq files were analyzed using RStudio 2022.07.1+554 for Windows. All samples were trimmed and aligned to a human reference genome and genome annotation (GRCh38.14, NCBI) using the Rsubread package (Ver 2.10.5). Feature counts were obtained and differentially expressed miRNA were identified using the DESeq2 package (Ver 1.36.0). Raw counts were normalized to sequence length and depth by calculating the reads per kilobase per million to identify uniquely expressed miRNA. Gene Ontology from the DAVID online tool was utilized to explore biological processes associated with the differentially expressed miRNAs. Further analysis of predicted gene targets was conducted using the miRDB.org tool. After alignment, there was an average of 46.5 million alignments across all samples and 23.9 million successful alignments resulting in an average of 51.2% successfully aligned reads to the reference genome. An average of 34 million features were counted across all samples with an average of 3 million counts for all known miRNAs. Differential expression analysis revealed 29 miRNAs were upregulated (log 2 fold change &gt;2, Padj &lt;0.05) following a single bout of moderate aerobic exercise. There were no miRNA significantly down regulated. Among the 29 miRNA, 2 (miRNA 483, l2fc = 2.7±0.68, Padj = 0.14 &amp; miRNA 3909, l2fc = Padj = 0.01) were identified in key biological processes linked to negative regulation of fat cell differentiation, inflammatory response, and blood vessel endothelial cell proliferation involved angiogenesis. One differentially expressed miRNA (miRNA 346 Padj = 0.03) was identified as a positive regulator of canonical Wnt signaling pathway involved in osteoblast differentiation. In sum, we identified 3 key miRNAs in skeletal muscle involved in regulating key biological processes in response to an acute bout of moderate intensity aerobic exercise. Future research should expand these findings by investigating interactions between identified miRNAs and target mRNA(s), and explore the existence of comparable responses in humans with known exercise response deficits such as obesity and/or aging. The study was supported by NIH/NIDDK grant R01DK094062 (CSK), the Mayo Clinic Metabolomics Resource Core through grant number U24DK100469 from the NIH/NIDDK and the Mayo Clinic CTSA grant UL1TR000135 from the National Center for Advancing Translational Sciences. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Nanoparticles enrichment to carbon felt electrodes for non-aqueous redox flow battery

Non-aqueous electrolytes enable redox flow batteries to achieve higher energy density. However, commercially available, pristine carbon felt electrodes display high overpotentials for electrochemical reactions in a non-aqueous medium. It is then crucial to develop stable high-performance electrodes which display low activation overpotentials, low ohmic losses, and high porosity to ensure uniform flow-through distribution of the electrolyte. This study acknowledges the influence of using attached carbon-based nanoparticles to the fibers of the supporting carbon-felt electrodes. The use of reduced graphene oxide, graphene, multi-walled carbon nanotubes (CNT), carbon black Vulcan XC72, and Ketjen carbon nanoparticles bounded to the support carbon felt electrode using a Nafion ionomer was assessed. Post-mortem analysis revealed that the nanoparticles remained attached to the fibers even after intense charge-discharge cycling. The carbon felt containing CNT added to the fibers displayed the best performance on running the charge/discharge electrochemical reactions while achieving a 23 % higher energy efficiency compared to commonly used electrodes. The addition of noble metal-based nanoparticles Pt-rGO displayed only a slightly better performance of rGO. Good binding of the carbon nanoparticles was obtained by the addition of the ionomer in a ratio of 15 wt%.

Effects of freeze-thaw cycles on methanogenic hydrocarbon degradation: Experiment and modeling

Cold regions are warming much faster than the global average, resulting in more frequent and intense freeze-thaw cycles (FTCs) in soils. In hydrocarbon-contaminated soils, FTCs modify the biogeochemical and physical processes controlling petroleum hydrocarbon (PHC) biodegradation and the associated generation of methane (CH4) and carbon dioxide (CO2). Thus, understanding the effects of FTCs on the biodegradation of PHCs is critical for environmental risk assessment and the design of remediation strategies for contaminated soils in cold regions. In this study, we developed a diffusion-reaction model that accounts for the effects of FTCs on toluene biodegradation, including methanogenic biodegradation. The model is verified against data generated in a 215 day-long batch experiment with soil collected from a PHC contaminated site in Ontario, Canada. The fully saturated soil incubations with six different treatments were exposed to successive 4-week FTCs, with temperatures oscillating between −10 °C and +15 °C, under anoxic conditions to stimulate methanogenic biodegradation. We measured the headspace concentrations and 13C isotope compositions of CH4 and CO2 and analyzed the porewater for pH, acetate, dissolved organic and inorganic carbon, and toluene. The numerical model represents solute diffusion, volatilization, sorption, as well as a reaction network of 13 biogeochemical processes. The model successfully simulates the soil porewater and headspace concentration time series data by representing the temperature dependencies of microbial reaction and gas diffusion rates during FTCs. According to the model results, the observed increases in the headspace concentrations of CH4 and CO2 by 87% and 136%, respectively, following toluene addition are explained by toluene fermentation and subsequent methanogenesis reactions. The experiment and the numerical simulation show that methanogenic degradation is the primary toluene attenuation mechanism under the electron acceptor-limited conditions experienced by the soil samples, representing 74% of the attenuation, with sorption contributing to 11%, and evaporation contributing to 15%. Also, the model-predicted contribution of acetate-based methanogenesis to total produced CH4 agrees with that derived from the 13C isotope data. The freezing-induced soil matrix organic carbon release is considered as an important process causing DOC increase following each freezing period according to the calculations of carbon balance and SUVA index. The simulation results of a no FTC scenario indicate that, in the absence of FTCs, CO2 and CH4 generation would decrease by 29% and 26%, respectively, and that toluene would be biodegraded 23% faster than in the FTC scenario. Because our modeling approach represents the dominant processes controlling PHC biodegradation and the associated CH4 and CO2 fluxes, it can be used to analyze the sensitivity of these processes to FTC frequency and duration driven by temperature fluctuations.

Exercise-induced changes in gene expression do not mediate post exertional malaise in Gulf War illness

BackgroundPost-exertional malaise (PEM) is considered a characteristic feature of chronic multi-symptom illnesses (CMI) like Gulf War illness (GWI); however, its pathophysiology remains understudied. Previous investigations in other CMI populations (i.e., Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) have reported associations between PEM and expression of genes coding for adrenergic, metabolic, and immune function. ObjectivesTo investigate whether PEM is meditated by gene expression in Veterans with GWI. MethodsVeterans with GWI (n = 37) and healthy control Gulf War Veterans (n = 25) provided blood samples before and after 30-min of cycling at 70% of age-predicted heart rate reserve. Relative quantification of gene expression, symptom measurements, and select cardiopulmonary parameters were compared between groups at pre-, 30 minpost-, and 24 hpost-exercise using a doubly multivariate repeated measures analysis of variance (RM-MANOVA). Mediation analyses were used to test indirect effects of changes in gene expression on symptom responses (i.e., PEM) to the standardized exercise challenge. ResultsVeterans with GWI experienced large symptom exacerbations following exercise compared to controls (Cohen's d: 1.65; p < 0.05). Expression of β-actin (ACTB), catechol-O-methyltransferase (COMT), and toll-like receptor 4 (TLR4) decreased in Veterans with GWI at 30 min (p < 0.05) and 24 h post-exercise (p < 0.05). Changes in gene expression did not mediate post-exercise symptom exacerbation in GWI (Indirect Effect Slope Coefficient: 0.06 – 0.02; 95% CI: 0.19, 0.12). ConclusionAn acute bout of moderate intensity cycling reduced the expression of select structural, adrenergic, and immune genes in Veterans with GWI, but the pathophysiological relevance to PEM is unclear.

POWER DEVELOPMENT IN THE STARTING PHASE OF SPEED RUNNING

ABSTRACT: Introduction: Short distance running is part of the maximum intensity cycling exercises, consisting of combined efforts, each step being performed as a result of a complete impulse, characterized by covering a distance in a shorter time. Objective: This study aims to follow the development of power for the start in short distance speed trials. Material and method: A 26-year-old male athlete, who has been practicing athletics for 14 years, participated in the study, based on the 100-meter flat sprint. The pre-test was performed before the preparation period, the intermediate test after one, two and three mesocycles (months) and the final test after the fourth mesocycle (after 4 months). The evaluations followed the strength with which 4 exercises were performed (deadlift, clean, power clean and squat) of 6 repetitions each. At the same time, the length of the distance covered in the first three steps from the start was followed. During the four mesocycles, the athlete participated in specific strength development training. Results: Following the training program for the development of lower limb power, execution speed and lower limb strength, statistically significant results were observed in 2 of the 4 exercises performed in the evaluations. Regarding the jumped step starting from the two different positions, an evolution was observed reaching from the length of 5.24m to 6.44m in the first variant, and from 5.31m to 5.93m in the second variant. In both cases the execution time of the three steps increased, reaching the value of 1.85s, respectively 1.49s. Conclusions: Following the results obtained in the five evaluations, we notice that the training program was developed efficiently and that the results improved in most of the evaluation tests.