| 1. |
- Sahlin, Kent
(author)
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Control of lipid oxidation at the mitochondrial level.
- 2009
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In: Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme. - : Canadian Science Publishing. - 1715-5312. ; 34:3, s. 382-8
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Journal article (peer-reviewed)abstract
- The rate of lipid oxidation during exercise is controlled at several sites, and there is a reciprocal dependency between oxidation of lipids and carbohydrates (CHO). It is well known that the proportion of the 2 fuels oxidized is influenced by substrate availability and exercise intensity, but the mechanisms regulating fuel preferences remain unclear. During intense exercise, oxidation of long-chain fatty acids (LCFAs) decreases, and the major control is likely to be at the mitochondrial level. Potential mitochondrial sites for control of lipid oxidation include transport of LCFAs into mitochondrial matrix, beta-oxidation, the tricarboxylic acid cycle, and the electron transport chain (ETC). CHO catabolism may impair lipid oxidation by interfering with the transfer of LCFAs into mitochondria and by competing for mutual cofactors (i.e., nicotinamide adenine dinucleotide and (or) coenzyme A (CoA)). The different effect of energy state on the catabolism of CHO and lipids is likely to be of major importance in explaining the shift in fuel utilization during intensive exercise. Formation of acetyl-CoA from CHO is activated by a low energy state, and will lead to accumulation of products that are inhibitory to lipid oxidation. In contrast, beta-oxidation of LCFAs to acetyl-CoA is not stimulated by a low energy state. Further interaction between CHO and LCFAs may occur by substrate competition for electron carriers at ETC, due to provisions of electrons through different complexes. Feedback inhibition of beta-oxidation by redox state is thought to be an important mechanism for the slowing of lipid oxidation during intensive exercise.
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| 2. |
- Beaven, C. Martyn, 1977-, et al.
(author)
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Effects of caffeine and carbohydrate mouth rinses on repeated sprint performance
- 2013
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In: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 38:6, s. 633-637
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Journal article (peer-reviewed)abstract
- Introduction: Our purpose was to examine the effectiveness of carbohydrate and caffeine mouth rinses on enhancing repeated sprint ability. Previously, beneficial effects of a carbohydrate mouth rinse (without ingestion) on endurance performance have been related to changes in brain activity. Caffeine ingestion has also demonstrated positive effects on sprint performance. However, the effects of carbohydrate or caffeine mouth rinses on intermittent sprints have not previously been examined. Methods: Twelve males performed 5 x 6 s sprints interspersed by 24 s of active recovery on a cycle ergometer. Twenty-five ml of either a non-caloric placebo, 6% glucose, or 1.2% caffeine solution was rinsed in the mouth for 5 s prior to each sprint in a double-blinded and balanced, cross-over design. Post-exercise maximal heart rate and perceived exertion were recorded along with power measures. A second experiment compared a combined caffeine-carbohydrate rinse with carbohydrate-only. Results: Compared to the placebo mouth rinse, carbohydrate substantially increased Sprint 1 peak power (22.1 ±19.5 W; ES: 0.81), and both caffeine (26.9 ±26.9 W; ES: 0.71) and carbohydrate (39.1 ±25.8 W; ES: 1.08) improved mean power in Sprint 1. Experiment 2 demonstrated that a combination of caffeine and carbohydrate improved Sprint 1 power production compared to carbohydrate alone (36.0 ±37.3 W; ES: 0.81). Conclusions: Carbohydrate and/or caffeine mouth rinses may rapidly enhance power production which could have benefits for specific short sprint exercise performance. The ability of a mouth rinse intervention to rapidly improve maximal exercise performance in the absence of fatigue suggests a central mechanism.
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| 3. |
- Beaven, Christopher Martyn, 1977-
(author)
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Intermittent lower-limb occlusion enhances recovery after strenuous exercise
- 2012
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In: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 37:6, s. 1132-1139
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Journal article (peer-reviewed)abstract
- Repeated cycles of vascular occlusion followed by reperfusion initiate a protective mechanism that acts to mitigate future cell injury. Such ischemic episodes are known to improve vasodilation, oxygen utilization, muscle function, and have been demonstrated to enhance exercise performance. Thus, the use of occlusion cuffs represents a novel intervention that may improve subsequent exercise performance. Fourteen participants performed an exercise protocol that involved lower-body strength and power tests followed by repeated sprints. Occlusion cuffs were then applied unilaterally (2 x 3-min per leg) with a pressure of either 220 (intervention) or 15 mm Hg (control). Participants immediately repeated the exercise protocol, and then again 24 h later. The intervention elicited delayed beneficial effects (24 h post-intervention) in the countermovement jump test with concentric (effect size (ES) = 0.36) and eccentric (ES = 0.26) velocity recovering more rapidly compared with the c! ontrol. There were also small beneficial effects on 10- and 40-m sprint times. In the squat jump test there were delayed beneficial effects of occlusion on eccentric power (ES = 1.38), acceleration (ES = 1.24), and an immediate positive effect on jump height (ES = 0.61). Thus, specific beneficial effects on recovery of power production and sprint performance were observed both immediately and 24 h after intermittent unilateral occlusion was applied to each leg.
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| 4. |
- Bellafronte, Natália Tomborelli, et al.
(author)
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A survey of preoperative surgical nutrition practices, opinions, and barriers across Canada
- 2024
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In: Applied Physiology, Nutrition and Metabolism. - : National Research Council Canada. - 1715-5312 .- 1715-5320. ; 49:5, s. 687-699
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Journal article (peer-reviewed)abstract
- Malnutrition is prevalent among surgical candidates and associated with adverse outcomes. Despite being potentially modifiable, malnutrition risk screening is not a standard preoperative practice. We conducted a cross-sectional survey to understand healthcare professionals' (HCP) opinions and barriers regarding screening and treatment of malnutrition. HCPs working with adult surgical patients in Canada were invited to complete an online survey. Barriers to preoperative malnutrition screening were assessed using the Capability Opportunity Motivation-Behaviour model. Quantitative data were analyzed using descriptive statistics and qualitative data were analyzed using summative content analysis. Of the 225 HCPs surveyed (n=111 dietitians, n=72 physicians, n=42 allied healthcare professionals), 96%-100% agreed that preoperative malnutrition is a modifiable risk factor associated with worse surgical outcomes and is a treatment priority. Yet, 65% (n=142/220; dietitians: 88% vs. physicians: 40%) reported screening for malnutrition, mostly in the postoperative period (n=117) by dietitians (n=94), and just 42% (48/113) of non-dietitian respondents referred positively screened patients to a dietitian for further assessment and treatment. The most prevalent barriers for malnutrition screening were related to opportunity, including availability of resources (57%, n=121/212), time (40%, n=84/212) and support from others (38%, n=80/212). In conclusion, there is a gap between opinion and practice among surgical HCPs pertaining to malnutrition. Although HCPs agreed malnutrition is a surgical priority, the opportunity to screen for nutrition risk was a great barrier.
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| 5. |
- Buckley, John P., et al.
(author)
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Borg's scales in strength training; from theory to practice in young and older adults
- 2011
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In: Applied Physiology, Nutrition and Metabolism. - 1715-5312 .- 1715-5320. ; 36:5, s. 682-692
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Journal article (peer-reviewed)abstract
- This study is the first to apply Borg's psychophysical equation to measuring responses to strength training with weights machines. Theoretical constructs of Borg's scales were assessed in younger and older adults to estimate the appropriate load and number of repetitions required to meet recommended practice guidelines. A younger group (YG; 20 males, 20 females; aged 19-38 years) and older group (OG; 13 males, 13 females; aged 50-75 years) participated in 3 experiments. Experiment 1: YG performed 2-repetitions of incremented loads during triceps-elbow extensions and knee extensions to level 7 on Borg's CR10 Scale. Experiment 2: YG (n = 16) then performed 12-repetitions at the loads from experiement 1 that elicited CR10 ratings 1.5, 3.0, and 5.0. Experiment 3: OG performed 15-repetitions of lat-pull and leg press at 15-repetition maximum (RM) load. In experiments 2 and 3, CR10 or Borg RPE were measured every 2 repetitions. Experiment 1 revealed classic psychophysical response growth exponents between 1.1 and 1.8, which were greater in arms than legs (p < 0.001) and in females (p < 0.001). Theoretical estimates of 1RM were derived from the growth curves for the weights eliciting CR10 ratings of 1.5, 3, and 5. CR10 ratings of 3 to 6 fell within estimates of 40%-70% 1RM. Experiments 2 and 3 revealed, for constant load exercise over time (12 and 15 repetitions) from an initial CR10 rating of 4 to 6, a linear increase of 1 scale point for every 3 to 4 repetitions. In conclusion, Borg's equation has been used to set theoretical estimates of a %1RM. Relevant to current practice guidelines was the ability to set appropriate loads in relation to performing recommended numbers of repetitions (e. g., if the CR10 rating is >6 after 2 repetitions, the weight is likely be too heavy to complete 12 to 15 repetitions).
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| 6. |
- Burd, NA, et al.
(author)
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Optimizing the measurement of mitochondrial protein synthesis in human skeletal muscle
- 2015
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In: Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. - : Canadian Science Publishing. - 1715-5320. ; 40:1, s. 1-9
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Journal article (peer-reviewed)abstract
- The measurement of mitochondrial protein synthesis after food ingestion, contractile activity, and/or disease is often used to provide insight into skeletal muscle adaptations that occur in the longer term. Studies have shown that protein ingestion stimulates mitochondrial protein synthesis in human skeletal muscle. Minor differences in the stimulation of mitochondrial protein synthesis occur after a single bout of resistance or endurance exercise. There appear to be no measurable differences in mitochondrial protein synthesis between critically ill patients and aged-matched controls. However, the mitochondrial protein synthetic response is reduced at a more advanced age. In this paper, we discuss the challenges involved in the measurement of human skeletal muscle mitochondrial protein synthesis rates based on stable isotope amino acid tracer methods. Practical guidelines are discussed to improve the reliability of the measurement of mitochondrial protein synthesis rates. The value of the measurement of mitochondrial protein synthesis after a single meal or exercise bout on the prediction of the longer term skeletal muscle mass and performance outcomes in both the healthy and disease populations requires more work, but we emphasize that the measurements need to be reliable to be of any value to the field.
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| 7. |
- Chen, Yung Chih, et al.
(author)
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Effects of neuromuscular electrical stimulation on energy expenditure and postprandial metabolism in healthy men
- 2022
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In: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 47:1, s. 27-33
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Journal article (peer-reviewed)abstract
- It is unclear whether neuromuscular electrical stimulation (NMES) has meaningful metabolic effects when users have the opportunity to self-select the intensity to one that can be comfortably tolerated. Nine healthy men aged 28 6 9y (mean 6 SD) with a body mass index 22.3 6 2.3 kg/m2 completed 3 trials involving a 2-h oral glucose tolerance test whilst, in a randomised counterbalanced order, (1) sitting motionless (SIT), (2) standing motionless (STAND); and (3) sitting motionless with NMES of quadriceps and calves at a self-selected tolerable intensity. The mean (95% confidence interval [CI]) total energy expenditure was greater in the NMES trial (221 [180–262] kcal/2 h) and STAND trial (178 [164–191] kcal/2 h) than during SIT (159 [150–167] kcal/2 h) (both, p < 0.05). This was primarily driven by an increase in carbohydrate oxidation in the NMES and STAND trials compared with the SIT trial (p < 0.05). Postprandial insulin iAUC was lower in both NMES and STAND compared with SIT (16.4 [7.7–25.1], 17 [7–27] and 22.6 [10.8–34.4] nmol·120 min/L, respectively; both, p < 0.05). Compared with sitting, both NMES and STAND increased energy expenditure and whole-body carbohydrate oxidation and reduced postprandial insulin concentrations in healthy men, with more pronounced effects seen with NMES. Self-selected NMES is a potential strategy for improving metabolic health. This trial is registered at ClinicalTrials.gov (ID: NCT04389736). Novelty: • NMES at a comfortable intensity enhances energy expenditure and carbohydrate oxidation, and reduces postprandial insulinemia. • Thus, self-selected NMES represents a potential strategy to improve metabolic health.
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| 8. |
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| 9. |
- Debevec, Tadej, et al.
(author)
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Whole body and regional body composition changes following 10-day hypoxic confinement and unloading-inactivity
- 2014
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In: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 39:3, s. 386-395
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Journal article (peer-reviewed)abstract
- Future planetary habitats will expose inhabitants to both reduced gravity and hypoxia. This study investigated the effects of short-term unloading and normobaric hypoxia on whole body and regional body composition (BC). Eleven healthy, recreationally active, male participants with a mean (SD) age of 24 (2) years and body mass index of 22.4 (3.2) kg.m(-2) completed the following 3 10-day campaigns in a randomised, cross-over designed protocol: (i) hypoxic ambulatory confinement (HAMB; FIO2 = 0.147 (0.008); PIO2 = 93.8 (0.9) mm Hg), (ii) hypoxic bed rest (HBR; FIO2 = 0.147 (0.008); PIO2 = 93.8 (0.9) mm Hg), and (iii) normoxic bed rest (NBR; FIO2 = 0.209; PIO2 = 133.5 (0.7) mmHg). Nutritional requirements were individually precalculated and the actual intake was monitored throughout the study protocol. Body mass, whole body, and regional BC were assessed before and after the campaigns using dual-energy X-ray absorptiometry. The calculated daily targeted energy intake values were 2071 (170) kcal for HBR and NBR and 2417 (200) kcal for HAMB. In both HBR and NBR campaigns the actual energy intake was within the targeted level, whereas in the HAMB the intake was lower than targeted (-8%, p < 0.05). Body mass significantly decreased in all 3 campaigns (-2.1%, -2.8%, and -2.0% for HAMB, HBR, and NBR, respectively; p < 0.05), secondary to a significant decrease in lean mass (-3.8%, -3.8%, -4.3% for HAMB, HBR, and NBR, respectively; p < 0.05) along with a slight, albeit not significant, increase in fat mass. The same trend was observed in the regional BC regardless of the region and the campaign. These results demonstrate that, hypoxia per se, does not seem to alter whole body and regional BC during short-term bed rest.
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| 10. |
- Dogan, Soner, et al.
(author)
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Roles of adiponectin and leptin signaling-related micrornas in the preventive effects of calorie restriction in mammary tumor development
- 2021
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In: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 46:8, s. 866-876
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Journal article (peer-reviewed)abstract
- Calorie restriction (CR) is suggested to prevent the development of mammary tumors (MTs); however, the mechanism remains to be clarified. We aimed to determine the microRNA (miRNA) profile in mice applied to 2 different CR protocols; chronic (CCR) and intermittent (ICR) and follow the MT development. In addition, the roles of miRNAs involved in adiponectin and/or leptin signaling pathways were investigated. Mice were divided into 3 groups: ad-libitum (AL), CCR, or ICR, which comprised 3 weeks of AL feeding followed by 1 week of 60% CR in a cyclic manner. Blood and tissue collection were performed at weeks 10, 17/18, 49/50 and 81/82. Long-term CCR provided better protection compared with ICR for MT development with a delay in the MT occurrence. Adiponectin expression in mammary fat pad were significantly higher in CCR group compared with AL. Using GeneChip Array, 250 of 3195 miRNAs were differentially expressed among the dietary groups. Thirteen of 250 miRNAs were related to adiponectin and/or leptin signaling genes. Results were verified by reverse transcription polymerase chain reaction. Specifically, miR-326-3p, miR-500-3p and miR-129-5p, which are related to adiponectin and/or leptin signaling, may play important roles in the preventive effects of CR in MT development and in ageing. Thus, these miRNAs might be putative biomarkers to target for diagnostic and treatment purposes. Novelty: Type of CR and micro RNA interaction is related to ageing. miR-326-3p, miR-500-3p and miR-129-5p expression levels were differentially expressed in MT development and in ageing. The genes associated with adiponectin and/or leptin signaling pathways are regulated by certain miRNAs in the protective effects of CR.
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