bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting mountain ultra‐marathon performance using the critical velocity model
Authors: Rogers Michael , Ngo My Linh , Sandberg Olivia , Atashzay Parmida , Singh Prabhjot , Malcolm Corrine , Clarke David , Walsh Michael , White Matthew 
Published: November 2023

PURPOSECritical Velocity (CV) and D′ were evaluated as predictors of mountain ultra marathon finishing times in cool conditions.HYPOTHESISIt was hypothesized that CV and D′ would both predict mountain ultra‐marathon performance.METHODSNine healthy males volunteered to participate in the study. Their average age was 37.9 ± 10.0 y, height 1.79 ± 0.05 m, body mass 76.6 ± 11.2 kg, BMI 23.8 ± 3.0 kg•m−2. The SFU Office of Research Ethics approved the study and each volunteer gave a signed consent prior to participation. Each volunteer completed a 50‐km mountain ultra‐marathon and then each volunteer's CV and D′ was evaluated using a series of maximal‐effort timed 1200, 2400 and 3600 m running trials on the same day with 30 min rest before trials 2 and 3. A Latin square design was employed to determine the orders of the tests. Maximal aerobic capacity was also assessed using indirect calorimetry and a graded treadmill test.RESULTSThe mean CV was 3.5 ± 0.5 m•s−1, D′ was 197.2 ± 83.2 m and mean absolute and relative aerobic powers were 4.8 ± 0.8 L min−1 and 63.5 ± 6.7 mL•kg−1•min−1, respectively. Stepwise multiple linear regression identified CV as the sole significant predictor of the mountain ultra‐marathon performance time (r=−0.88, p<0.05). Correlation analysis of the independent variables with finishing time indicated that aerobic power was significantly and positively correlated with finishing times (r=−0.72, p=0.002).CONCLUSIONThese preliminary results suggest that CV explains both a significant fraction of the variance in mountain marathon finishing time and that CV obtained via running track tests is an appropriate method for predicting these finishing times.Support or Funding InformationSupported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canadian Foundation for Innovation (CFI)
Effects of the Different Acute Exercise on Melatonin of Undergraduate
Authors: Sun Youping , He Jing , Qiu Linli 
Published: November 2023

OBJECTIVETo compare the effects of different acute exercise on Melatonin of undergraduate.METHODSSubjects (n=160)were randomized into endurance training(E, n=40), strength training (S, n=40), combined strength and endurance training(SE, n=40), or control group(C, n=40)for 45min, and take 4ml venous blood at before and after training.RESULTS1、 The Melatonin of female significantly increased in E (10.30±3.20 17.41±4.33; P < 0.05). Melatonin significantly increased in S (10.30±18.49; 16.96±5.00; P < 0.05). Melatonin significantly increased in SE (7.09±2.44; 15.53±6.96; P < 0.01). But it increased no significantly in C also (9.98±1.61; 14.56±2.5; P > 0.05). 2、 The Melatonin of male significantly increased in E (7.82±2.39; 23.22±2.69; P < 0.01). Melatonin significantly increased in S (9.30±6.17; 16.36±5.58; P < 0.05), Melatonin significantly increased in SE (8.19±4.69; 17.92±2.01; P < 0.01), but it increased no significantly in C (10.81±3.87; 13.87±6.34; P > 0.05). 3、 There were no significant difference on the change of the four groups (female: P > 0.05; male: P > 0.05).CONCLUSIONEndurance training and Strength training and their combination all led to increase in Melatonin. The different acute exercises have no significant difference influence on Melatonin.Support or Funding InformationThe key lab of adolescent health intervention and exercise assessment, Ministry of China
Autonomic cardiovascular response during the isometric Cuban test of the sustained weight
Authors: Sanchez‐Hechavarria Miguel , Carrazana‐Escalona Ramon , Ricardo‐Ferro Beatriz , Cutino‐Clavel Ileana , Lopez‐Galan Erislandis 
Published: November 2023

IntroductionThe Test of the Sustained Weight (TSW) is an isometric exercise, similar to hand grip, often used in Cuba to induce hemodynamic responses in order to identify individuals with cardiovascular hyperreactivity. However the dynamic changes in the autonomic cardiovascular responses are not totally elucidated.ObjectiveDetermining the autonomic cardiovascular response during the isometric Cuban test of the sustained weight.MethodsWe used a quasi‐experimental (crossover) design of 20 healthy subjects. Following 10 min for acclimation, we evaluated 5 min before (basal), 2 min during TSW, and 3 min of recovery while performing ausculatory blood pressure measurement and analysis of the variability of the RR intervals (HRV) from DII derivation of ECG record (1kHz) using Powerlab® AD Instruments. R‐R intervals were analyzed using frequency (Fourier) and time‐frequency (Wavelet) methods of the bands of high frequency (HF: 0,15–0,4) and low frequency (LF: 0,04–0,15), as well as temporal and nonlinear (Sample Entropy) analysis.ResultsWe did not observe significant differences in the indicators of the temporal (SDNN, RMSSD, pNN50) and frequency analyses (LF, HF, LF/HF). We did observe a significant change in arterial pressure in the TSW with respect to rest and this was associated with the increment of complexity (entropy) and with a peak in the LF and ratio LF/HF around the 2 min reflected by time‐frequency methods.ConclusionsThe dynamic changes in the sympathetic cardiovascular response during the Test of the Sustained Weight are not evident with traditional lineal methods of HRV due to the non‐stationary and to the increment of the complexity of this physiologic process with regard to basal state.Support or Funding InformationSupported by University of Santiago de Cuba, Cuba.
Habitual Physical Activity Level Modifies Lung Function, But Not 8‐Isoprostane Generation, in Older Adults
Authors: Kurti Stephanie P. , Emerson Sam R. , Rosenkranz Sara K. , Smith Joshua R. , Harms Craig A. 
Published: November 2023

INTRODUCTIONThe development of asthma and chronic obstructive pulmonary disease is associated with elevated 8‐isoprostane (validated marker of oxidative stress) in the airways and systemically. Acutely, a single bout of exhaustive exercise elicits an increase in oxidative stress, which may lead to cardiorespiratory complications in older adults. Habitual physical activity (PA), however, is a natural anti‐oxidant and anti‐inflammatory. Therefore our purpose was to elucidate whether older adults who are active (OA) exhibit an attenuated airway and systemic 8‐isoprostane response to maximal exercise compared to older adults who are insufficiently active (IA). A secondary purpose was to determine whether chronic PA level in older adults modifies post‐exercise lung function.METHODSSeventeen older adults (≥60 years of age) completed the study (9 OA/ 8 IA: 65.1± 3.9 years). Subjects came into the laboratory for a single testing session after wearing an Actical accelerometer on their non‐dominant wrist to verify they were in the correct PA group. Upon arrival to the laboratory, baseline measurements were performed as follows: exhaled breath condensate (EBC) to assess airway 8‐isoprostane; an antecubital venipuncture for assessment of systemic 8‐isoprostane; followed by standard pulmonary function testing (PFTs) for assessment of forced expiratory volume in 1‐second (FEV1), forced vital capacity (FVC), FEV1/FVC, and forced expiratory flow at 25–75% of FVC (FEF25–75%). Subjects then completed an incremental cycle exercise test to reach peak oxygen consumption (VO2peak). Immediately following the VO2peak test, subjects performed post‐exercise PFTs, and a trained investigator took a post‐exercise blood draw directly prior to EBC.RESULTSThere were no differences in airway (p=0.55) or systemic (p=0.94) 8‐isoprostane between OA and IA subjects. In the OA and IA combined, there was not a significant change in the generation of airway 8‐isoprostane (14.3±30.7%; p=0.10) or systemic 8‐isoprostane (13.9±69.3%; p=0.62) from pre‐ to post‐exercise. Habitual PA level did not impact 8‐isoprostane generation in the airways (p=0.62) or systemically (p=0.66) from pre‐ to post‐exercise. Post‐exercise FEV1 and FEF25–75% increased from pre‐ to post‐exercise in both groups (p<0.05), however the OA showed a greater post‐exercise bronchodilation as FEV1/FVC increased by 3.1±2.5% compared to 0.4±2.7% in the IA group (p=0.04). No other indices of lung‐function were different between OA and IA (p>0.05).CONCLUSIONSOur results suggest that habitual PA level does not impact the generation of airway and systemic 8‐isoprostane in response to exhaustive exercise in older adults. However, it appears that engaging in more PA per week elicits greater post‐exercise bronchodilation in older adults who are chronically physically active. These results suggest a potential bronchoprotective role for chronic PA in older adults.
SHORT TERM HIGH FAT FEEDING ALTERS EXPRESSION OF GLUCOREGULATORY PROTEINS IN SKELETAL MUSCLE OF MALE ADOLESCENT RATS
Authors: Crawford Melisa Shaunte , Liss Tyler , Sweazea Karen 
Published: November 2023

Childhood obesity affects approximately 17% of children and adolescents in the United States. Prolonged consumption of energy‐dense foods, in addition to a sedentary lifestyle, continue to increase the prevalence of overweight and obese adolescents. Unfortunately, this trend is accompanied by serious metabolic conditions including, type II diabetes, cardiovascular disease, and skeletal muscle atrophy. Skeletal muscle, the most abundant tissue in the human body, is responsible for insulin‐mediated glucose uptake and many of the metabolic abnormalities associated with obesity. While it is known that a high‐fat diet (HFD) can impair insulin signaling, endothelium‐dependent vasodilation and increase the risk of oxidative stress, less is known about the effects of a short‐term HFD on skeletal muscle of adolescents. We hypothesized that short‐term high fat intake by adolescent rats would promote similar pathologies observed with chronic poor nutrition in adults. To examine this, six‐week‐old male Sprague Dawley rats were fed either a standard rodent chow diet (18.9% protein, 57.33% carbohydrates) or a HFD (20% protein, 20% carbohydrates [6.8% sucrose], 60% fat) for 6 weeks. Blood samples were collected then animals were euthanized (sodium pentobarbital; 200 mg/kg, i.p.) and pectoralis major muscles were extracted for analyses. Consistent with the development of obesity and type II diabetes, HFD rats had significantly lower plasma α‐amylase (24.7% decrease; p=0.007). However, Oil Red‐O and triglyceride assays showed no significant increase in muscle lipids (p>0.05). Data also suggests no significant increase in expression of proteins associated with insulin signaling (p‐PI3K; p=0.462) and inflammation (iNOS; p=0.406). In contrast, there was a tendency towards increased expression of the alpha subunit of the insulin receptor (180.9%, p=0.076) as well as the insulin‐responsive (GLUT‐4; 83.9%, p=0.093) and insulin‐independent (GLUT‐1; 89.9%, p=0.103) glucose transporters. The increased expression of these latter proteins likely reflect early compensation for the HFD. Further studies will confirm these findings and examine the effects of a short‐term HFD on the progression of inflammation, macrophage invasion and the impairment of insulin signaling intermediates in skeletal muscle of adolescent rats.Support or Funding InformationThis project was partially funded by the Barrett Honors College, Arizona State University
High Air‐Pressure Elevated Energy Expenditure in Mice
Authors: Xiang Dao , Fang Yiqun , Luo Beibei , Yan Shuo , Xu Ji , Chen Peijie 
Published: November 2023

PURPOSEWhen diving or working underwater, people would be exposed to the air‐pressure higher than standard atmospheric pressure. The higher pressure would be an extra load for divers to do exercises or even breathe. And the extra load would alter divers' energy expenditure (EE). Our study examined the effects of high‐pressure exposure on energy expenditure in mice.METHOD6 male C57 Mice, 8‐week old, were kept in pressure chamber separately with N2/O2 mixed gas at standard atmospheric pressure (101kPa). The temperature of the chamber was maintained at 22□ (±1.0 □). The energy expenditure was assessed by indirect calorimetric measurement. After acclimated to the chambers for 30 minutes, O2 consumption (ΔVO2 0m) and CO2 production (ΔVCO2 0m) of those mice within a sampling period (10 minutes) were recorded. Between periods was a 5‐minute venting. The exposure lasted for 6 hours. Then after 24 hours normal feed, mice exposed to N2/O2 mixed gas at 700kPa (to mimic 60 meters under water) for 6 hours in pressure chamber individually. The O2 consumption (ΔVO2 60m) and CO2 production (ΔVCO2 60m) were recorded as described before. The energy expenditure of mice under high pressure and under standard atmospheric pressure were compared.RESULTSMice under high pressure consumed 5341.38±1666.02 ml oxygen and produced 4212.62±1116.23 ml CO2 per‐hour per‐kg bodyweight during the 6‐hour exposure. While under standard atmospheric pressure, the oxygen consumption was 2360.19±586.12 ml and CO2 production was 1930.55±503.85 ml per‐hour per‐kg bodyweight. The energy expenditure of mice under high pressure within 6 hours exposure (25.47±7.75 kcal/h.kg) were significantly higher than mice under standard atmospheric pressure (11.37±2.83 kcal/h.kg).CONCLUSIONHigh‐pressure exposure markedly elevated oxygen consumption and CO2 production, as well as energy expenditure in mice. The main cause might be the extra load from breathing air with higher density.
Investigating the effects of hyperbaric oxygen on mitochondrial function of endothelial progenitor cells.
Authors: Aylin‐Burns Nukhet , Krager Kimberly J. , Zhou Daohong , Hauer‐Jensen Martin 
Published: November 2023

Hyperbaric oxygen treatment (HBOT) is a FDA approved adjunctive therapy for 14 different conditions, including delayed radiation injury, impaired wound healing, compromised skin grafts and compression sickness. Patients typically receive multiple daily treatments in chambers pressurized up to 3.0 atmospheres with 100% oxygen, depending on the disease state/type. We previously demonstrated that HBOT stimulates vasculogenic stem cell growth and differentiation in vivo, by creating a physiological redox‐active autocrine loop in circulating progenitor cells. Recent studies also supported the role of HBOT in activation of redox‐regulated pathways including hypoxia inducible factor (HIF), mitogen‐activated protein kinase (MAPK), thioredoxin (Trx) system, nuclear factor erythroid 2 (Nrf2) as well as nitric oxide (NO) signaling. In this study we proposed that alterations in mitochondrial function is an early event following HBOT. Mice were treated with HBO for 90 min at 2.8 ATA. Cellular bioenergetics and mitochondrial respiration were assessed immediately following treatment in primary cells using Seahorse Extracellular flux analyzer. Oxygen consumption rate (OCR) was measured after the sequential injections of oligomycin (inhibitor of ATP synthase), carbonyl cyanide p‐trifluoromethoxyphenylhydrazone (FCCP; uncoupler of mitochondrial inner membrane), and antimycin A (inhibitor of complex III). HBOT significantly altered the basal respiration as well as spare respiratory capacity. Furthermore, the mitochondrial mass is significantly increased following a single HBOT session. Future studies will determine the effect of multiple HBOT sessions on mitochondrial function and cellular bioenergetics, which can provide novel targets to improve the efficacy of an already safe and approved therapy.Support or Funding InformationThis project is funded by NIGMS, Center of Biomedical Research Excellence Award, P20GM109005
Exaggerated sympathetic and pressor responses to exercise pressor reflex activation are attenuated by intracerebroventricular insulin administration in type 2 diabetic rats
Authors: Mizuno Masaki , Mitchell Jere , Smith Scott A 
Published: November 2023

The cardiovascular response to exercise is abnormally exaggerated in patients with type 2 diabetes mellitus (T2D). We have previously demonstrated that stimulation of the exercise pressor reflex (EPR) during muscle contraction elicits exaggerated increases in renal sympathetic nerve activity (RSNA) contributing significantly to this heightened circulatory responsiveness. However, the mechanisms underlying this EPR dysfunction remain to be elucidated. Evidence suggests that the availability of brain insulin is reduced in T2D. Given that sympathetic activity is primarily regulated within the brain, we hypothesized that a decrease in brain insulin contributes to EPR‐induced sympathetic overactivity in this disease. To test this hypothesis, we measured changes in RSNA and mean arterial pressure (MAP) during stimulation of the EPR in decerebrated Sprague‐Dawley rats given either a normal diet (control) or a high fat diet (in combination with a one‐time low dose of streptozotocin to produce T2D) for 14–16 weeks. Compared to normal diet‐fed rats, animals receiving the high fat diet had significantly increased plasma insulin (1.6±0.2 vs. 4.1±0.4 ng/mL, P<0.05) as well as fasting blood glucose (94±5 vs. 120±5 mg/dL, P<0.05). Compared to control animals, stimulation of the EPR by electrically‐induced muscle contraction evoked significantly greater increases in RSNA (Δ = 36±10 vs. 122±20 %, P<0.05) and MAP (Δ = 15±1 vs. 49±5 mmHg, P<0.05) in T2D rats. Intracerebroventricular insulin administration significantly attenuated the exaggerated sympathetic (Δ = 111±20 vs. 50±17 %, P=0.05) and pressor responses (Δ = 49±5 vs. 12±4 mmHg, P<0.05) to EPR activation in T2D rats but did not have a significant effect in control animals (RSNA: Δ = 43±2 vs. 33±13 %; MAP: Δ = 15±1 vs. 7±4 mmHg). These findings suggest that the heightened cardiovascular response to exercise in T2D may be mediated by EPR‐induced sympathetic dysfunction resulting as a consequence of decreased insulin availability within the brain.Support or Funding InformationSupported by the Lawson & Rogers Lacy Research Fund in Cardiovascular Disease.
Expression and Distribution of Pro‐Inflammatory Cytokines within Dorsal Root Ganglion of Rats with Femoral Artery Occlusion
Authors: Li Jianhua , Lu Jian , Xing Jihong 
Published: November 2023

Using a rat model of peripheral arterial disease (PAD), prior studies have demonstrated that augmented sympathetic nerve and blood pressure responses evoked by activation of the exercise pressor reflex are attenuated after blocking activities of pro‐inflammatory cytokines (PICs) such as IL‐6 and TNF‐α. The present study was to examine the protein expression levels of PICs in dorsal root ganglion (DRG) of control rats and rats with 72 hours of femoral artery occlusion. Our results show that femoral occlusion significantly enhanced the levels of IL‐1β, IL‐6 and TNF‐α as compared with controls (P<0.05, n=6 in each group). In addition, peripherin and NF200 were used to determine DRG neurons supplied by A‐fiber containing group III fiber and C‐fiber/group IV thin fiber, respectively. We observed that IL‐1β and IL‐6 were present in peripherin‐ and NF200‐positive DRG neurons, whereas TNF‐α was found for the most part in only peripherin‐positive DRG neurons. Expression levels of PIC receptors including IL‐6R and TNFR1 were also found to be upregulated in DRG of rats with femoral artery occlusion (P<0.05 vs. control rats). Overall, our data suggest that PIC mechanisms contribute to augmented sympathetic responsiveness likely via the mechanical and metabolic component of the exercise pressor reflex when arterial blood supply to the hindlimb is deficient under ischemic conditions as observed in PAD.Support or Funding InformationNIH P01 HL096570 and AHA Established Investigator Award 0840130N
Sex Differences in Sympathetic Vasoconstrictor Responsiveness and Sympatholysis
Authors: Just Timothy P , DeLorey Darren S 
Published: November 2023

Sympathetic nervous system control of blood pressure and skeletal muscle vascular resistance appears to differ between males and females. The mechanism(s) responsible for sex differences in neurovascular control have not been fully elucidated. Nitric Oxide (NO) has been shown to inhibit sympathetic vasoconstriction in resting and contracting skeletal muscle and estrogen appears to modulate NO synthase (NOS) expression and NO bioavailability. The relative abundance of estrogen in females compared to males suggests that NO‐mediated inhibition of sympathetic vasoconstriction may be augmented in females relative to males. Therefore, the purpose of the present study was to investigate the hypothesis that compared to males, females would have blunted sympathetic vasoconstrictor responsiveness and augmented NO‐mediated inhibition of sympathetic vasoconstriction at rest and during exercise. Male (n=8) and Female (n=10) Sprague‐Dawley rats were anesthetized and surgically instrumented for measurement of arterial blood pressure and femoral artery vascular conductance (FVC) and stimulation of the lumbar sympathetic chain. The percentage change of FVC (%FVC) in response to sympathetic chain stimulation delivered at 2 and 5 Hz was determined at rest and during triceps surae muscle contraction before (control) and after NOS‐blockade (L‐NAME; 10 mg·kg−1 IV). At rest, vasoconstrictor responsiveness to sympathetic stimulation delivered at 2Hz was augmented (p<0.05) in females (−33 ± 8%) compared to males (−26 ± 6%), whereas vasoconstrictor responsiveness to sympathetic stimulation delivered at 5Hz was not different (p>0.05) between females (−55 ± 7%) and males (−47 ± 7%). Muscle contraction blunted (p<0.05) sympathetic vasoconstrictor responsiveness in both female and male rats; however the magnitude of sympatholysis was greater (p<0.05) in female (2Hz: 22 ± 8%; 5Hz: 30 ± 7%) compared to male (2Hz: 12 ± 6%; 5Hz: 13 ± 8%) rats. NOS blockade did not alter (p>0.05) sympatholysis of responses evoked at 2Hz in females or males; however L‐NAME reduced (p<0.05) sympatholysis of responses evoked at 5Hz in female rats. These data demonstrate that resting sympathetic vasoconstrictor responsiveness was augmented in female rats compared to male rats in a stimulation frequency‐dependent manner. Furthermore, sympatholysis was enhanced in female compared to male rats and this was partly attributable to augmented NO‐mediated inhibition of sympathetic vasoconstriction.Support or Funding InformationNatural Sciences and Engineering Research Council of Canada (NSERC), Canadian Foundation for Innovation, and Alberta Advanced Education and Technology.