2019

Permanent URI for this collectionhttps://hdl.handle.net/1807/92942

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    Effect of high-dose vitamin D supplementation in combination with weight loss diet on glucose homeostasis, insulin resistance, and matrix metalloproteinases in obese subjects with vitamin D deficiency: a double-blind, placebo-controlled, randomized clinical trial
    (Canadian Science Publishing, 2019-03-13) Aliashrafi, Soodabeh; Ebrahimi-Mameghani, Mehrangiz; Jafarabadi, Mohammad Asghari; Lotfi-Dizaji, Lida; Vaghef-Mehrabany, Elnaz; Arefhosseini, Seyed-Rafie
    As there is limited and inconsistent evidence in potential role of vitamin D on insulin resistance and matrix metalloproteinases, this study aimed to examine the effect of vitamin D supplementation on glucose homeostasis, insulin resistance, and matrix metalloproteinases in obese subjects with vitamin D deficiency. A total of 44 participants with serum 25-hydroxyvitamin D (25(OH)D) level ≤ 50 nmol/L and body mass index (BMI) 30–40 kg/m2 were randomly allocated into receiving weight reduction diet with either 50 000 IU vitamin D3 pearl (n = 22) or placebo (n = 22) once weekly for 12 weeks. Primary outcomes were changes in fasting serum glucose (FSG), homeostasis model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and matrix metalloproteinases (MMPs). Secondary outcomes were changes in weight, BMI, 25(OH)D, calcium, phosphorous and parathyroid hormone (PTH). Sun exposure and dietary intakes were also assessed. Serum levels of 25(OH)D3 increased significantly with a simultaneous decrease in serum concentration of PTH in the vitamin D group. Weight, BMI, FSG, and MMP-9 decreased significantly in both groups, and there were significant differences in changes in weight, serum 25(OH)D3, PTH, and MMP-9 levels between the groups. Within- and between-groups analysis revealed no significant differences in serum calcium, phosphorous, serum insulin, HOMA-IR, QUICKI, and MMP-2 after intervention. Our results indicated that improvement in vitamin D status resulted in greater reductions in weight and MMP-9 during weight loss. These preliminary results are sufficient to warrant a bigger study group.
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    Aerobic exercise training attenuates detrimental effects of cigarette smoke exposure on peripheral muscle through stimulation of the Nrf2 pathway and cytokines: a time-course study in mice
    (Canadian Science Publishing, 2019-12-09) Toledo-Arruda, Alessandra C.; de Sousa Neto, Ivo Vieira; Vieira , Rodolfo P.; Guarnier, Flávia A.; Caleman-Neto, Agostinho; Suehiro, Camila L.; Olivo, Clarice R.; Cecchini, Rubens; Prado, Carla M.; Lin, Chin J.; Durigan, João Luiz Quaglioti; Martins, Milton A.
    Cigarette smoke (CS) exposure reduces skeletal muscle function; however, the mechanisms involved have been poorly investigated. The current study evaluated the temporal effects of aerobic exercise training on oxidant and antioxidant systems as well as inflammatory markers in skeletal muscle of mice exposed to CS. Mice were randomly allocated to control, exercise, smoke, and smoke+exercise groups and 3 time points (4, 8, and 12 weeks; n = 12 per group). Exercise training and CS exposure were performed for 30 min/day, twice a day, 5 days/week for 4, 8, and 12 weeks. Aerobic exercise improved functional capacity and attenuated the increase in the cachexia index induced by CS exposure after 12 weeks. Concomitantly, exercise training downregulated tumor necrosis factor α concentration, glutathione oxidation, and messenger RNA (mRNA) expression of Keap1 (P < 0.01) and upregulated interleukin 10 concentration, total antioxidant capacity, and mRNA expression of Nrf2, Gsr, and Txn1 (P < 0.01) in muscle. Exercise increased mRNA expression of Hmox1 compared with the control after 12 weeks (P < 0.05). There were no significant differences between smoke groups for superoxide dismutase activity and Hmox1 mRNA expression. Exercise training improved the ability of skeletal muscle to adequately upregulate key antioxidant and anti-inflammatory defenses to detoxify electrophilic compounds induced by CS exposure, and these effects were more pronounced after 12 weeks. Novelty Exercise attenuates oxidative stress in skeletal muscle from animals exposed to CS via Nrf2 and glutathione pathways. Exercise is a helpful tool to control the inflammatory balance in skeletal muscle from animals exposed to CS. These beneficial effects were evident after 12 weeks.
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    Dietary Salvia hispanica L. reduces cardiac oxidative stress of dyslipemic insulin-resistant rats
    (Canadian Science Publishing, 2019-12-28) Creus, Agustina; Chicco, Adriana; Álvarez, Silvina M.; Giménez, María S.; Bolzón de Lombardo, Yolanda
    Salvia hispanica L., commonly known as chia seed, has beneficial effects upon some signs of metabolic syndrome (MS), such as dyslipidemia and insulin resistance. However, its action on cardiac oxidative stress associated with MS remains unknown. The goal of this study was to analyze the possible beneficial effects of chia seed (variety Salba) upon the oxidative stress of left ventricle heart muscle (LV) of a well-established dyslipidemic insulin-resistant rat model induced by feeding them a sucrose-rich diet (SRD). Male Wistar rats received an SRD for 3 months. After that, for 3 additional months, half of the animals continued with the SRD, while the other half received the SRD containing chia as the source of dietary fat instead corn oil (SRD+chia). In the LV of SRD-fed rats, chia seed improved/reverted the depleted activity of antioxidant enzymes glutathione peroxidase, superoxide dismutase (SOD), and catalase, and ameliorated manganese superoxide dismutase messenger RNA (mRNA) levels increasing the expression of the nuclear factor erythroid 2-related factor 2 (Nrf2). Improved the glutathione redox estate, reactive oxygen species, and thiobarbituric acid reactive substances contents normalizing the p47NOX subunit mRNA level. Furthermore, chia normalized hypertension and plasma levels of pro-inflammatory cytokines and oxidative stress biomarkers. The findings show that chia seed intake impacts positively upon oxidative imbalance of LV of dyslipidemic insulin-resistant rats. Novelty Healthy effects of chia seed involve an improvement of cardiac antioxidant defenses through Nrf2 induction. Chia seed intake reduces cardiac oxidative stress markers of dyslipidemic insulin-resistant rats. Dietary chia seed restores cardiac unbalanced redox state of dyslipidemic insulin-resistant rats.
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    Detrimental Association between Quadriceps Strength and Exposure to Polycyclic Aromatic Hydrocarbons in Elderly Adults
    (Canadian Science Publishing, 2019-12-31) Chen, Yuan-Yuei; Wang, Chung-Ching; Kao, Tung-Wei; Yang, Hui-Fang; Sun, Yu-Shan; Chen, Wei-Liang
    Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants primarily from the incomplete combustion of organic materials. Myriads of studies have reported the associations between PAH exposure with several adverse health outcomes. However, no previous study had explored the relationship between PAH exposure with muscle strength in the elderly population. In the present study, we included 473 elderly adults who were obtained from the US National Health and Nutrition Examination Survey (NHANES) (2001–2006). PAH metabolites were measured in urine samples. Muscle strength was determined as the isokinetic strength of the quadriceps. Pertinent variables were analyzed by various standard measurements. The association between PAH exposure and muscle strength was examined using multivariable linear regression models. After fully adjusting for covariables, PAH metabolites had a negative relationship with muscle strength, especially 3-fluorene (β = –0.021, 95% CI: –0.042, 0.000) and 2-fluorene (β = –0.020, 95% CI: –0.034, –0.005). Notably, the relationship remained significant in males, but not in females. PAH exposure is associated with decreased muscle strength in the US elderly population. Further studies are needed to bring to light the underlying mechanisms for these findings. In addition, it is important to provide interventions and determine strategies for treating the adverse impact of PAH exposure on dynapenia. Novelty PAH exposure is associated with decreased muscle strength in elderly adults. The adverse impact remains in males.
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    Time to exhaustion during cycling is not well predicted by critical power calculations
    (Canadian Science Publishing, 2019-12-31) Pallarés, Jesus G.; Lillo-Bevia, Jose R.; Morán-Navarro, Ricardo; Cerezuela-Espejo , Victor; Mora-Rodriguez, Ricardo
    Three to 5 cycling tests to exhaustion allow prediction of time to exhaustion (TTE) at power output based on calculation of critical power (CP). We aimed to determine the accuracy of CP predictions of TTE at power outputs habitually endured by cyclists. Fourteen endurance-trained male cyclists underwent 4 randomized cycle-ergometer TTE tests at power outputs eliciting (i) mean Wingate anaerobic test (WAnTmean), (ii) maximal oxygen consumption, (iii) respiratory compensation threshold (VT2), and (iv) maximal lactate steady state (MLSS). Tests were conducted in duplicate with coefficient of variation of 5%–9%. Power outputs were 710 ± 63 W for WAnTmean, 366 ± 26 W for maximal oxygen consumption, 302 ± 31 W for VT2 and 247 ± 20 W for MLSS. Corresponding TTE were 00:29 ± 00:06, 03:23 ± 00:45, 11:29 ± 05:07, and 76:05 ± 13:53 min:s, respectively. Power output associated with CP was only 2% lower than MLSS (242 ± 19 vs. 247 ± 20 W; P < 0.001). The CP predictions overestimated TTE at WAnTmean (00:24 ± 00:10 mm:ss) and MLSS (04:41 ± 11:47 min:s), underestimated TTE at VT2 (–04:18 ± 03:20 mm:ss; P < 0.05), and correctly predicted TTE at maximal oxygen consumption. In summary, CP accurately predicts MLSS power output and TTE at maximal oxygen consumption. However, it should not be used to estimate time to exhaustion in trained cyclists at higher or lower power outputs (e.g., sprints and 40-km time trials). Novelty CP calculation enables to predict TTE at any cycling power output. We tested those predictions against measured TTE in a wide range of cycling power outputs. CP appropriately predicted TTE at maximal oxygen consumption intensity but err at higher and lower cycling power outputs.
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    Discriminating hypothalamic oligomenorrhea/amenorrhea from hyperandrogenic oligomenorrhea/amenorrhea in exercising women
    (Canadian Science Publishing, 2019-11-17) Koltun, Kristen J.; Williams, Nancy I; Scheid, Jennifer L.; De Souza, Mary Jane
    The mechanism underlying oligo/amenorrhea in exercising women is often presumed as hypothalamic inhibition secondary to energy deficiency; however, hyperandrogenism may provide an alternative mechanism in some exercising women. Our purpose was to compare reproductive, metabolic, and androgen profiles of exercising women with eumenorrheic, ovulatory menstrual cycles (n = 91), oligo/amenorrhea without evidence of hyperandrogenism (Oligo/Amen; n = 83), and oligo/amenorrhea with evidence of hyperandrogenism (Oligo/Amen-HA; n = 17), and determine the prevalence of oligo/amenorrhea with evidence of hyperandrogenism in exercising women. Self-reported menstrual history and quantification of daily estrogen and progesterone urinary metabolites determined reproductive status. Resting energy expenditure, body composition, and metabolic hormone concentrations determined metabolic status. Serum androgens and calculated free androgen index (FAI) determined androgen status. Groups were similar in age (22.4 ± 0.3 years), height (165.1 ± 0.5 cm), resting energy expenditure (1198.4 ± 12.0 kcal/day), and total triiodothyronine (85.0 ± 1.5 ng/dL) concentration. Oligo/Amen-HA had greater weight (60.0 ± 1.6, 56.1 ± 0.7 kg), body mass index (22.3 ± 0.4, 20.6 ± 0.2 kg/m2), percentage body fat (27.3% ± 1.4%, 24.4% ± 0.6%), fat mass (16.2 ± 1.0, 13.8 ± 0.4 kg), insulin (5.8 ± 0.7, 4.2 ± 0.3 μIU/mL), leptin (12.2 ± 2.3, 6.6 ± 0.7 ng/mL), FAI (6.1 ± 0.3, 1.7 ± 0.1), and luteinizing hormone/follicle-stimulating hormone (1.9 ± 0.3, 1.3 ± 0.2) compared with Oligo/Amen, respectively. In our sample, 17% of those with oligo/amenorrhea had concurrent hyperandrogenism. This study supports that oligo/amenorrhea in some exercising women is related to hyperandrogenism. Novelty Caution must be utilized when discriminating hypothalamic oligo/amenorrhea from hyperandrogenic oligo/amenorrhea. In our sample, 17% of those with presumed hypothalamic oligo/amenorrhea had concurrent hyperandrogenism. Exercise and/or mild energy deficiency may be protective against developing severe hyperandrogenic symptoms.
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    Variability of regional quadriceps echo intensity in active young men with and without subcutaneous fat correction
    (Canadian Science Publishing, 2019-12-31) Oranchuk, Dustin J.; Stock, Matt S.; Nelson, André R.; Storey, Adam G.; Cronin, John B.
    Quantifying echo intensity (EI), a proposed measure of muscle quality, is becoming increasingly popular. Additionally, much attention has been paid to regional differences in other ultrasonically evaluated measures of muscle morphology and architecture. However, the variability of regional (proximal, middle, distal) EI of the vastus lateralis, rectus femoris, and lateral and anterior vastus intermedius has yet to be determined. Twenty participants (40 limbs), were evaluated on 3 occasions, separated by 7 days. Intersession variability of EI with and without subcutaneous fat correction was quantified. Furthermore, the interchangeability of corrected EI across regions was evaluated. Variability of regional quadriceps EI was substantially lower with subcutaneous fat correction (intraclass correlation coefficient (ICC) = 0.81–0.98, coefficient of variation (CV) = 4.5%–16.8%, typical error of measure (TEM) = 0.13–0.49) versus raw values (ICC = 0.69–0.98, CV = 7.7%–42.7%, TEM = 0.14–0.68), especially when examining the vastus intermedius (ICC = 0.81–0.95, CV = 7.1%–16.8%, TEM = 0.23–0.49 vs. ICC = 0.69–0.92, CV = 22.9%–42.7%, TEM = 0.31–0.68). With the exception of the rectus femoris and vastus intermedius (p ≥ 0.143, effect size (ES) ≤ 0.18), corrected EI was greater for proximal and distal regions when compared with the midpoint (p ≤ 0.038, ES = 0.38–0.82). Researchers and practitioners should utilize subcutaneous fat thickness correction to confidently evaluate EI at all regions of the quadriceps. Regional EI cannot be used interchangeably for the vastus muscles, likely because of an increase in fibrous content towards the myotendinous junctions. Novelty Regional quadriceps echo intensity was reliable with and without correction for subcutaneous fat thickness. Intersession variability of regional quadriceps echo intensity was substantially improved following subcutaneous fat correction. Quadriceps echo intensity increased towards myotendinous junctions in the vastus muscles.
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    A new aerobic fitness score based on lactate sensing during submaximal exercise
    (Canadian Science Publishing, 2019-12-13) Hagar, Amit; Melo, Luma; Hills, Grace; Kenshur, Nathan; Dickinson, Stephanie
    Given the known clinical utility of cardiorespiratory fitness, measurement of physiological responses to submaximal exercise may be a feasible approach well suited for diagnostic and prognostic purposes in non-athletes and the chronically ill. Lactate levels and watt output during a short submaximal exercise and a subsequent relaxation period yield an aerobic score that is consistent with cardiorespiratory fitness grades in non-athletes and that may be used as a marker in such approaches. In this study, 28 females (23 ± 3 years) were submitted to a 15 min submaximal recumbent bike session, and their capillary and saliva lactate concentrations were recorded and plotted against time. An individual aerobic score was calculated from this curve, using watt output during equal relative percentiles of maximum heart-rate benchmarks. The scores were compared with respective results in a V̇O2max test and with a similar scoring system in 14 older (51 ± 9 years) females; they correlated with the 6 categories of the V̇O2max test results and classified into 3 categories of V̇O2max grades (very poor/poor; fair/good; excellent/superior) with a combined accuracy of 80.95%. More studies are required to validate the potential utility of this submaximal test as an additional risk factor for diagnostic purposes in non-athletes. Novelty points: A novel method for estimating cardiorespiratory fitness during submaximal exercise consistent with V̇O2max performance. The method yields an aerobic score that may be used as a marker for diagnostic and prognostic purposes.
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    Aerobic exercise training-induced irisin secretion is associated with the reduction of arterial stiffness via nitric oxide production in adults with obesity
    (Canadian Science Publishing, 2019-12-12) Inoue, Kenichiro; Fujie, Shumpei; Hasegawa, Natsuki; Horii, Naoki; Uchida, Masataka; Iemitsu, Keiko; Sanada, Kiyoshi; Hamaoka, Takafumi; Iemitsu, Motoyuki
    This study aimed to clarify whether muscle-derived irisin secretion induced by aerobic exercise training is involved in reduction of arterial stiffness via arterial nitric oxide (NO) productivity in obesity. In animal study, 16 Otsuka Long-Evans Tokushima Fatty (OLETF) rats with obesity were randomly divided into 2 groups: sedentary control (OLETF-CON) and 8-week aerobic treadmill training (OLETF-EX) groups. In human study, 15 subjects with obesity completed 8-week aerobic exercise training for 45 min at 60%–70% peak oxygen uptake intensity for 3 days/week. As a result of animal study, carotid-femoral pulse wave velocity (cfPWV) was decreased, and arterial phosphorylation levels of AMP-activated protein kinase (AMPK), protein kinase B (Akt), and endothelial NO synthase (eNOS), circulating levels of nitrite/nitrate (NOx) and irisin, and muscle messenger RNA expression of fibronectin type III domain containing 5 (Fndc5) were increased in the OLETF-EX group compared with OLETF-CON group. In a human study, regular aerobic exercise reduced cfPWV and elevated circulating levels of NOx and irisin. Furthermore, change in circulating irisin levels by regular exercise was positively correlated with circulating NOx levels and was negatively correlated with cfPWV. Thus, aerobic exercise training-induced increase in irisin secretion may be related to reduction of arterial stiffness achieved by NO production via activated arterial AMPK–Akt–eNOS signaling pathway in obesity. Novelty Aerobic exercise training promoted irisin secretion with upregulation of muscle Fndc5 gene expression in rats with obesity. Irisin affected the activation of arterial AMPK–Akt–eNOS signaling by aerobic exercise training. Increased serum irisin level by aerobic exercise training was associated with reduction of arterial stiffness in obese adults.
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    Anti-ulcerogenic activity of Gum Arabic in gastric mucosal injury induced by ethanol in male albino rats
    (Canadian Science Publishing, 2019-12-11) Taha, Mervat Sayed; El-Sherbiny, Emad Mohamed; Osman, Hala Fawzy
    The present study was performed to evaluate the anti-ulcerogenic activity of Acacia senegal (Gum Arabic) against ethanol-induced gastric mucosal injury in rats. Thirty-six adult male albino rats were divided into 4 groups: group 1 served as a control; group 2 consisted of rats that received 15% of gum in drinking water for 2 weeks; group 3 comprised ulcerated animals administered 5 mL of ethanol/kg body weight by gavage; and group 4 consisted of rats received 15% of gum in drinking water for 2 weeks before ethanol administration. Superoxide dismutase (SOD) glutathione peroxidase (GPx), malondialdehyde (MDA), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), interleukin (IL)-B1), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total protein, and albumin were assayed in addition to histological study. The results revealed that ethanol decreased SOD, GPx, and PGE2 in tissue and serum total protein and albumin, while increased MDA in tissue, serum TNF-α, IL-B1, PGE2, ALT, AST, and ALP. Histological findings showed less edema and leucocytes infiltration compared with ulcer group. Furthermore, gum administration elevated PGE2, SOD, and GPx and significantly reduced MDA, TNF-α, and IL-B2. In conclusion, Gum Arabic can enhance gastric protection and sustain the integrity of the gastric mucosa. Novelty The selected dose of Gum Arabic has the ability to decrease the pro-inflammatory cytokines in plasma and gastric tissue, thus enhancing gastric protection and maintaining the integrity of the gastric mucosa. Gum Arabic can compensate for the loss of antioxidants.
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    Association between serum choline and betaine concentrations and longitudinal changes of body composition in community-dwelling middle-aged and older Chinese adults
    (Canadian Science Publishing, 2019-12-17) Zhong, Rong-huan; Long, Jing-an; Wang, Fan; Chen, Si; Luo, Yun; Lu, Xiao-ting; Yishake, Dinuerguli; Chen, Yu-Ming; Fang, Ai-ping; Zhu, Hui-lian
    Previous studies suggest that betaine and choline may be beneficial for body composition. However, no longitudinal study has been conducted to illustrate if choline and betaine have long-term effects on changes in body composition. This study aimed to prospectively investigate the association between serum choline and betaine concentrations and 3-year changes in body composition in community-dwelling Chinese adults. This present analysis used data from 1384 women and 554 men aged 40–75 years. Serum concentrations of betaine and choline at baseline were assessed using high-performance liquid chromatography-tandem mass spectrometry. Body composition parameters, i.e., muscle mass (MM), fat mass (FM), and body fat percentage (FM%) were measured using dual-energy X-ray absorptiometry at the first and the second follow-ups. After adjustment for potential cofounders, higher serum choline concentrations were associated with a lower decrease in MM in men (β = 0.022, P = 0.025) and a lower increase in FM and FM% in women with baseline choline concentrations below 21.5 μmol/L (all P for nonlinearity = 0.007); higher serum betaine concentrations were associated with a lower decline in MM and a lower increase in FM and FM% among men whose betaine concentrations were lower than 55 μmol/L (all P for nonlinearity < 0.05). These findings suggest that higher concentrations of serum choline and betaine may be associated with favorable changes in body composition profiles among men and women who have relatively low concentrations, especially in men. Novelty Higher concentrations of serum choline and betaine were associated with favorable changes in body composition. Such favorable associations were more pronounced in men.
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    A novel gravity-induced blood flow restriction model augments ACC phosphorylation and PGC-1α mRNA in human skeletal muscle following aerobic exercise: a randomized crossover study
    (Canadian Science Publishing, 2019-11-19) Preobrazenski, Nicholas; Islam, Hashim; Drouin, Patrick J.; Bonafiglia, Jacob T; Tschakovsky, Michael E; Gurd, Brendon J
    This study tested the hypothesis that a novel, gravity-induced blood flow restricted (BFR) aerobic exercise (AE) model will result in greater activation of the AMPK–PGC-1α pathway compared with work rate-matched non-BFR. Thirteen healthy males (age: 22.4 ± 3.0 years; peak oxygen uptake: 42.4 ± 7.3 mL/(kg·min)) completed two 30-min work rate-matched bouts of cycling performed with their legs below (CTL) and above their heart (BFR) at ∼2 weeks apart. Muscle biopsies were taken before, immediately, and 3 h after exercise. Blood was drawn before and immediately after exercise. Our novel gravity-induced BFR model led to less muscle oxygenation during BFR compared with CTL (O2Hb: p = 0.01; HHb: p < 0.01) and no difference in muscle activation (p = 0.53). Plasma epinephrine increased following both BFR and CTL (p < 0.01); however, only norepinephrine increased more following BFR (p < 0.01). PGC-1α messenger RNA (mRNA) increased more following BFR (∼6-fold) compared with CTL (∼4-fold; p = 0.036). VEGFA mRNA increased (p < 0.01) similarly following BFR and CTL (p = 0.21), and HIF-1α mRNA did not increase following either condition (p = 0.21). Phosphorylated acetyl-coenzyme A carboxylase (ACC) increased more following BFR (p < 0.035) whereas p-PKA substrates, p-p38 MAPK, and acetyl-p53 increased (p < 0.05) similarly following both conditions (p > 0.05). In conclusion, gravity-induced BFR is a viable BFR model that demonstrated an important role of AMPK signalling on augmenting PGC-1α mRNA. Novelty Gravity-induced BFR AE reduced muscle oxygenation without impacting muscle activation, advancing gravity-induced BFR as a simple, inexpensive BFR model. Gravity-induced BFR increased PGC-1α mRNA and ACC phosphorylation more than work rate-matched non-BFR AE. This is the first BFR AE study to concurrently measure blood catecholamines, muscle activation, and muscle oxygenation.
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    Menstrual blood losses and body mass index are associated with serum ferritin concentrations among female varsity athletes
    (Canadian Science Publishing, 2019-11-16) Mayer, Cara; Barker, Mikaela K; Dirk, Payge; Moore, Kelsey M; McCrudden, Emma; Karakochuk, Crystal D
    Preventing and treating iron deficiency are important components in the nutritional care of female varsity athletes, as these interventions may improve aerobic endurance and athletic performance. We examined the factors associated with ferritin concentration in 30 female varsity athletes (18–30 years) at the University of British Columbia in Vancouver, Canada. Biochemical indicators of iron and inflammation status, dietary intake, supplementation practices, weight, height, and menstrual blood losses were assessed. Iron deficiency prevalence was 20% (n = 6/30; inflammation-adjusted ferritin <15 μg/L). Multiple linear regression was used to assess the associations of a number of independent explanatory variables with log-transformed serum ferritin (μg/L) as the continuous outcome variable. A 1-unit increase in body mass index (BMI; kg/m2) was associated with 22% (95% CI: 9%–37%) higher mean ferritin concentrations, and a 1-point increase in menstrual loss score was associated with 1% (95% CI: 1%–2%) lower ferritin concentrations. Hemoglobin and hepcidin concentrations, inflammation biomarkers, consumption of iron supplements in any form or dose for ≥3 days/week, and age were not significantly associated with ferritin concentrations in the final adjusted model. Novelty Estimated monthly menstrual losses and BMI were associated with serum ferritin concentrations in female athletes in our study. These are easy-to-measure, noninvasive measurements that should be considered in the assessment of risk of iron deficiency in female athletes.
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    Effect of blood flow occlusion on neuromuscular fatigue following sustained maximal isometric contraction
    (Canadian Science Publishing, 2019-12-02) Oranchuk, Dustin J.; Koral, Jérôme; da Mota, Gustavo R.; Wrightson, James G.; Soares, Rogério; Twomey, Rosie; Millet, Guillaume Y.
    Sustained isometric maximal voluntary contractions (IMVCs) have blood flow occlusive effects on the microvasculature. However, it is unknown if this effect would be magnified with additional blood flow restriction via a cuff and what the influence on fatigue development would be. Twelve healthy male participants performed a 1-min IMVC of the knee extensors with and without additional blood flow occlusion induced by pneumatic cuff in counterbalanced order on separate days. Vastus lateralis muscle deoxygenation was estimated via near-infrared spectroscopy–derived tissue oxygen saturation (SmO2) throughout the fatiguing contraction. Central and peripheral measures of neuromuscular fatigue (NMF) were assessed via surface electromyography (EMG) and force responses to voluntary contractions and peripheral nerve/transcranial magnetic stimulations before, immediately after, and throughout an 8-min recovery period. SmO2, force, and EMG amplitude decreased during the 1-min IMVC, but there were no between-condition differences. Similarly, no significant (p > 0.05) between-condition differences were detected for any dependent variable immediately after the fatiguing contraction. Transcranial magnetic stimulation (TMS)-derived voluntary activation was lower (p < 0.05) in the no-cuff condition during the recovery period. Sustained IMVC results in a similar degree of muscle deoxygenation and NMF as IMVCs with additional occlusion, providing further evidence that a sustained IMVC induces full ischemia.
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    Impact of resistance training program configuration on the circulating brain-derived neurotrophic factor response
    (Canadian Science Publishing, 2019-11-22) Quiles, Justin M; Klemp, Alex; Dolan, Chad; Maharaj, Arun; Huang, Chun-Jung; Khamoui, Andy V; Trexler, Eric T; Whitehurst, Michael; Zourdos, Michael C
    This study examined the acute and resting changes of brain-derived neurotrophic factor (BDNF) and inteleukin-6 (IL-6) and if changes in these biomarkers were correlated during resistance training (RT). Fifteen men with ≥2 years of RT experience (age: 23 ± 3 years, body mass: 84.4 ± 12.3 kg) participated. Subjects performed RT 3×/week for 6 weeks in either a high-repetition (HR; n = 8) or low-repetition (LR; n = 7) group. Protocols during week 1 were HR – Monday: 4 (sets) × 12 (repetitions) at 60% of 1-repetition maximum, Wednesday: 4 × 10 at 65%, Friday: 5 × 8 at 70%; LR – Monday: 8 × 6 at 75%, Wednesday 9 × 4 at 80%, Friday: 10 × 2 at 85%. Total volume was equated for the 6 weeks but not for individual sessions. Greater volume and intensity were performed in LR versus HR (p < 0.01) on Mondays. Plasma was collected immediately before and after exercise of the Monday session. There were no significant interactions or main effects for BDNF (p > 0.05). There was a moderate between-group effect size (0.57) in favor of LR in week 6, suggesting a potentially greater acute increase in BDNF in LR versus HR. For IL-6, a statistically significant main effect was observed for training (p < 0.0001), showing an acute increase in IL-6 in both weeks (p < 0.01); however, no other 3-way or 2-way interactions existed (p > 0.05). A minimum volume threshold of RT may be needed to induce acute elevations in BDNF. Novelty A minimum RT volume threshold may be needed to elicit BDNF. A close proximity to failure may be needed to elicit BDNF. BDNF and IL-6 did not correlate.
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    The effect of the artificial sweeteners on glucose metabolism in healthy adults: a randomized double-blinded crossover clinical trial
    (Canadian Science Publishing, 2019-10-29) Ahmad, Samar Y.; Friel, James K.; MacKay, Dylan S.
    This study aimed to determine the effect of pure forms of sucralose and aspartame, in doses reflective of common consumption, on glucose metabolism. Healthy participants consumed pure forms of a non-nutritive sweetener (NNS) that were mixed with water and standardized to doses of 14% (0.425 g) of the acceptable daily intake (ADI) for aspartame and 20% (0.136 g) of the ADI for sucralose every day for 2 weeks. Blood samples were collected and analyzed for glucose, insulin, active glucagon-like peptide-1 (GLP-1), and leptin. Seventeen participants (10 females and 7 males; age, 24 ± 6.8 years; body mass index, 22.9 ± 2.5 kg/m2) participated in the study. The total area under the curve values of glucose, insulin, active GLP-1 and leptin were similar for the aspartame and sucralose treatment groups compared with the baseline values in healthy participants. There was no change in insulin sensitivity after NNS treatment compared with the baseline values. These findings suggest that daily repeated consumption of pure sucralose or aspartame for 2 weeks had no effect on glucose metabolism among normoglycaemic adults. However, these results need to be tested in studies with longer durations. Novelty Daily consumption of pure aspartame or sucralose for 2 weeks had no effect on glucose metabolism. Daily consumption of pure aspartame or sucralose for 2 weeks had no effect on insulin sensitivity among healthy adults.
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    Reduced inflammatory and phagocytotic responses following normobaric hypoxia exercise despite evidence supporting greater immune challenge
    (Canadian Science Publishing, 2019-11-08) Hill, Garrett W.; Gillum, Trevor L.; Lee, Ben J.; Romano, Phebe A.; Schall, Zach J.; Kuennen, Matthew R.
    This study examined changes in immune markers following sustained treadmill exercise in normobaric hypoxia. Ten subjects performed 1 h of treadmill exercise (65% maximal oxygen uptake) under normoxic (NORM: fraction of inspired oxygen (FIO2) = 20.9%) and normobaric hypoxic (HYP: FIO2 = 13.5%) conditions. Blood samples, collected before, after (Post), 1 h after (1-Post), and 4 h after (4-Post) exercise, were assayed for plasma cytokines (interleukin (IL)-1RA/IL-1β/IL-8/tumor necrosis factor alpha (TNF-α)) and markers of leukocyte activation (macrophage inflammatory protein-1β (MIP-1β)/myeloperoxidase (MPO)/soluble intercellular adhesion molecule-1 (sICAM-1)) using ELISA. Pro- to anti-inflammatory cytokine ratios (TNF-α/IL-1RA; IL-1β/IL-1RA) were calculated. Peripheral blood mononuclear cells (PBMC) were analyzed for changes in inflammatory status (phosphorylated nuclear factor kappa B/nuclear factor kappa B) using Western Blot. Data were analyzed with 2-way (condition × time) repeated-measure ANOVAs with Newman–Keuls post hoc tests. MIP-1β was elevated at 1-Post HYP exercise (+11%; p < 0.01) but did not increase following exercise in NORM. TNF-α/IL-1RA and IL-1β/IL-1RA ratios were both reduced (p < 0.05) following HYP exercise (−16% and −52%, respectively, at 1-Post and −7% and −32%, respectively, at 4-Post). IL-8 increased (p < 0.05) at Post and 1-Post NORM (+33% and +57%, respectively) and HYP (+60% and +83%, respectively) exercise, but was not different between conditions (p > 0.05). Interestingly, plasma sICAM-1 did not increase (p > 0.05) following NORM exercise but was increased (p < 0.05) at Post (+17%), 1-Post (+16%), and 4-Post (+14%) HYP exercise. There was also a delayed peak in plasma MPO concentrations following HYP exercise and PBMC exhibited a reduced (p < 0.05) inflammatory capacity at Post (−38%) and 1-Post (−49%). Novelty Following HYP exercise, participants exhibited (i) circulatory bias towards anti-inflammation; (ii) elevated sICAM; (iii) delayed peak in plasma MPO; and (iv) diminished inflammatory response in PBMC. Collectively, these data suggest immunosuppression. This is undesirable, given that elevated MIP-1β (reported here) and elevated intestinal fatty acid binding protein (reported previously) both suggest higher lipopolysaccharide concentrations following HYP exercise.
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    Prediction modelling of 1-year outcomes to a personalized lifestyle intervention for Canadians with metabolic syndrome
    (Canadian Science Publishing, 2019-11-12) Lowry, Dana E.; Feng, Zeny; Jeejeebhoy, Khursheed; Dhaliwal, Rupinder; Brauer, Paula; Royall, Dawna; Tremblay, Angelo; Klein, Doug; Mutch, David M.
    Metabolic syndrome (MetS) comprises a cluster of risk factors that includes central obesity, hypertension, dyslipidemia, and impaired glucose homeostasis. Although lifestyle interventions reduce MetS risk, not everyone responds to the same extent. The primary objective of this study was to identify variables that could predict 1-year changes in MetS risk in individuals participating in the Canadian Health Advanced by Nutrition and Graded Exercise (CHANGE) program. Participants were allocated into training (n = 157) and test (n = 29) datasets by availability of genetic data. A linear mixed-effect model revealed that age, medication, fasting glucose, triglycerides, high-density lipoprotein cholesterol, waist circumference, systolic blood pressure, and fibre intake were associated with continuous MetS (cMetS) score across all time points. Multiple linear regressions were then used to build 2 prediction models using 1-year cMetS score as the outcome variable. Model 1 included only baseline variables and was 38% accurate for predicting cMetS score. Model 2 included both baseline variables and the 3-month change in cMetS score and was 86% accurate. As a secondary objective, we also examined if we could build a model to predict a person’s categorical response bin (i.e., positive responder, nonresponder, or adverse responder) at 1 year using the same variables. We found 72% concordance between predicted and observed outcomes. These various prediction models need to be further tested in independent cohorts but provide a potentially promising new tool to project patient outcomes during lifestyle interventions for MetS. Novelty Short-term changes in cMetS score improve prediction model performance compared with only baseline variables. Predictive models could potentially facilitate clinical decision-making for personalized treatment plans.
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    Brain-derived neurotrophic factor is associated with human muscle satellite cell differentiation in response to muscle-damaging exercise
    (Canadian Science Publishing, 2019-10-02) McKay, Bryon R.; Nederveen, Joshua P.; Fortino, Stephen A.; Snijders, Tim; Joanisse, Sophie; Kumbhare, Dinesh A.; Parise, Gianni
    Muscle satellite cell (SC) regulation is a complex process involving many key signalling molecules. Recently, the neurotrophin brain-derived neurotropic factor (BDNF) has implicated in SC regulation in animals. To date, little is known regarding the role of BDNF in human SC function in vivo. Twenty-nine males (age, 21 ± 0.5 years) participated in the study. Muscle biopsies from the thigh were obtained prior to a bout of 300 maximal eccentric contractions (Pre), and at 6 h, 24 h, 72 h, and 96 h postexercise. BDNF was not detected in any quiescent (Pax7+/MyoD−) SCs across the time-course. BDNF colocalized to 39% ± 5% of proliferating (Pax7+/MyoD+) cells at Pre, which increased to 84% ± 3% by 96 h (P < 0.05). BDNF was only detected in 13% ± 5% of differentiating (Pax7−/MyoD+) cells at Pre, which increased to 67% ± 4% by 96 h (P < 0.05). The number of myogenin+ cells increased 95% from Pre (1.6 ± 0.2 cells/100 myofibres (MF)) at 24 h (3.1 ± 0.3 cells/100 MF) and remained elevated until 96 h (cells/100 MF), P < 0.05. The proportion of BDNF+/myogenin+ cells was 26% ± 0.3% at Pre, peaking at 24 h (49% ± 3%, P < 0.05) and remained elevated at 96 h (P < 0.05). These data are the first to demonstrate an association between SC proliferation and differentiation and BDNF expression in humans in vivo, with BDNF colocalization to SCs increasing during the later stages of proliferation and early differentiation. Novelty BDNF is associated with SC response to muscle injury. BDNF was not detected in nonactivated (quiescent) SCs. BDNF is associated with late proliferation and early differentiation of SCs in vivo in humans.
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    The effects of aerobic exercise intensity on memory in older adults
    (Canadian Science Publishing, 2019-10-11) Kovacevic, Ana; Fenesi, Barbara; Paolucci, Emily; Heisz, Jennifer J.
    Aerobic exercise may enhance memory in older adults. However, the optimal intensity and underlying mechanism are unclear. This community-based study examined the effect of aerobic exercise intensity on memory and general cognitive abilities. Brain-derived neurotrophic factor (BDNF) was examined as a potential mechanism. Sixty-four sedentary older adults participated in 1 of 3 groups: (i) high-intensity interval training (HIIT); (ii) moderate continuous training (MCT); or (iii) stretching control (CON). Prior to and following the intervention, high-interference memory was assessed using a Mnemonic Similarity task and executive functions were assessed using Go Nogo and Flanker tasks. HIIT led to the greatest memory performance compared with MCT and CON (F[2,55] = 6.04, p = 0.004) and greater improvements in memory correlated with greater increases in fitness (rs (46) = 0.27, p = 0.03). Exercise intensity seemed to matter less for executive functioning, as positive trends were observed for both HIIT and MCT. No significant differences in BDNF were found between groups. Overall, these results suggest that aerobic exercise may enhance memory in older adults, with the potential for higher intensity exercise to yield the greatest benefit. While our findings suggest that BDNF does not regulate these adaptations, the mechanisms remain to be determined. Novelty • High-intensity interval training results in the greatest memory performance in inactive older adults compared to moderate continuous training or stretching • Improvement in fitness correlates with improvement in memory performance