| 1. |
- Beaven, C. Martyn, 1977-, et al.
(författare)
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Effects of caffeine and carbohydrate mouth rinses on repeated sprint performance
- 2013
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 38:6, s. 633-637
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Beaven, Christopher Martyn, 1977-
(författare)
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Intermittent lower-limb occlusion enhances recovery after strenuous exercise
- 2012
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 37:6, s. 1132-1139
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Bellafronte, Natália Tomborelli, et al.
(författare)
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A survey of preoperative surgical nutrition practices, opinions, and barriers across Canada
- 2024
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : National Research Council Canada. - 1715-5312 .- 1715-5320. ; 49:5, s. 687-699
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Buckley, John P., et al.
(författare)
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Borg's scales in strength training; from theory to practice in young and older adults
- 2011
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Ingår i: Applied Physiology, Nutrition and Metabolism. - 1715-5312 .- 1715-5320. ; 36:5, s. 682-692
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Burd, NA, et al.
(författare)
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Optimizing the measurement of mitochondrial protein synthesis in human skeletal muscle
- 2015
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. - : Canadian Science Publishing. - 1715-5320. ; 40:1, s. 1-9
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Chen, Yung Chih, et al.
(författare)
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Effects of neuromuscular electrical stimulation on energy expenditure and postprandial metabolism in healthy men
- 2022
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 47:1, s. 27-33
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Tidskriftsartikel (refereegranskat)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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| 7. |
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| 8. |
- Debevec, Tadej, et al.
(författare)
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Whole body and regional body composition changes following 10-day hypoxic confinement and unloading-inactivity
- 2014
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 39:3, s. 386-395
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Dogan, Soner, et al.
(författare)
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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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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 46:8, s. 866-876
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Tidskriftsartikel (refereegranskat)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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| 10. |
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| 11. |
- Engel, Florian Azad, et al.
(författare)
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The kinetics of blood lactate in boys during and following a single and repeated all-out sprints of cycling are different than in men
- 2015
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 40:6, s. 623-631
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Tidskriftsartikel (refereegranskat)abstract
- This study characterized the impact of high-intensity interval training on the kinetics of blood lactate and performance in trained boys and men. Twenty-one boys (11.4 +/- 0.8 years) and 19 men (29.4 +/- 5.0 years) performed a set of four 30-s sprints with 2-min of rest and a single 30-s sprint on 2 separate occasions (randomized order) with assessment of performance. Blood lactate was assayed after each sprint and during 30 min of recovery from both tests. The individual time-curves of blood lactate concentration were fitted to the biexponential function as follows: [LA](t) = [LA](0) + A(1) (1 - e(-gamma 1t)) +A(2) (1 - e (-gamma 2t)), where the velocity parameters gamma(1) and gamma(2) reflect the capacity to release lactate from the previously active muscle into the blood and to subsequently eliminate lactate from the organism, respectively. In both tests, peak blood lactate concentration was significantly lower in the boys (four 30-s sprints: 12.2 +/- 3.6 mmol.L-1; single 30-s sprint: 8.7 +/- 1.8 mmol.L-1) than men (four 30-s sprints: 16.1 +/- 3.3 mmol.L-1; single 30-s sprint: 11.5 +/- 2.1; p < 0.001). The boys exhibited faster gamma(1) (1.4531 +/- 0.65 min; p < 0.001) and gamma(2) (0.059 +/- 0.023 min; p = 0.01) in the single 30-s sprint and faster gamma(2) (0.049 +/- 0.016 min; p = 0.01) in the four 30-s sprints. The worsening of performance from the first to the last of the four 30-s sprints was less pronounced in boys (9.2% +/- 13.9%) than men (19.2% +/- 11.5%; p = 0.01). In the present study boys, when compared with men, exhibited lower Peak blood lactate concentration; less pronounced decline in performance during the sprints concomitantly with more rapid release and elimination during the single 30-s sprint; and faster elimination of lactate following the four 30-s sprints.
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| 12. |
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| 13. |
- Gul, SS, et al.
(författare)
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Inhibition of the gut enzyme intestinal alkaline phosphatase may explain how aspartame promotes glucose intolerance and obesity in mice
- 2017
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. - : Canadian Science Publishing. - 1715-5320. ; 42:1, s. 77-83
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Tidskriftsartikel (refereegranskat)abstract
- Diet soda consumption has not been associated with tangible weight loss. Aspartame (ASP) commonly substitutes sugar and one of its breakdown products is phenylalanine (PHE), a known inhibitor of intestinal alkaline phosphatase (IAP), a gut enzyme shown to prevent metabolic syndrome in mice. We hypothesized that ASP consumption might contribute to the development of metabolic syndrome based on PHE’s inhibition of endogenous IAP. The design of the study was such that for the in vitro model, IAP was added to diet and regular soda, and IAP activity was measured. For the acute model, a closed bowel loop was created in mice. ASP or water was instilled into it and IAP activity was measured. For the chronic model, mice were fed chow or high-fat diet (HFD) with/without ASP in the drinking water for 18 weeks. The results were that for the in vitro study, IAP activity was lower (p < 0.05) in solutions containing ASP compared with controls. For the acute model, endogenous IAP activity was reduced by 50% in the ASP group compared with controls (0.2 ± 0.03 vs 0.4 ± 0.24) (p = 0.02). For the chronic model, mice in the HFD + ASP group gained more weight compared with the HFD + water group (48.1 ± 1.6 vs 42.4 ± 3.1, p = 0.0001). Significant difference in glucose intolerance between the HFD ± ASP groups (53 913 ± 4000.58 (mg·min)/dL vs 42 003.75 ± 5331.61 (mg·min)/dL, respectively, p = 0.02). Fasting glucose and serum tumor necrosis factor-alpha levels were significantly higher in the HFD + ASP group (1.23- and 0.87-fold increases, respectively, p = 0.006 and p = 0.01). In conclusion, endogenous IAP’s protective effects in regard to the metabolic syndrome may be inhibited by PHE, a metabolite of ASP, perhaps explaining the lack of expected weight loss and metabolic improvements associated with diet drinks.
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| 14. |
- Hall, Ulrika Andersson, et al.
(författare)
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Whole-body fat oxidation increases more by prior exercise than overnight fasting in elite endurance athletes.
- 2016
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme. - : Canadian Science Publishing. - 1715-5320. ; 41:4, s. 430-7
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to compare whole-body fat oxidation kinetics after prior exercise with overnight fasting in elite endurance athletes. Thirteen highly trained athletes (9 men and 4 women; maximal oxygen uptake: 66 ± 1 mL·min(-1)·kg(-1)) performed 3 identical submaximal incremental tests on a cycle ergometer using a cross-over design. A control test (CON) was performed 3 h after a standardized breakfast, a fasting test (FAST) 12 h after a standardized evening meal, and a postexercise test (EXER) after standardized breakfast, endurance exercise, and 2 h fasting recovery. The test consisted of 3 min each at 30%, 40%, 50%, 60%, 70%, and 80% of maximal oxygen uptake and fat oxidation rates were measured through indirect calorimetry. During CON, maximal fat oxidation rate was 0.51 ± 0.04 g·min(-1) compared with 0.69 ± 0.04 g·min(-1) in FAST (P < 0.01), and 0.89 ± 0.05 g·min(-1) in EXER (P < 0.01). Across all intensities, EXER was significantly higher than FAST and FAST was higher than CON (P < 0.01). Blood insulin levels were lower and free fatty acid and cortisol levels were higher at the start of EXER compared with CON and FAST (P < 0.05). Plasma nuclear magnetic resonance-metabolomics showed similar changes in both EXER and FAST, including increased levels of fatty acids and succinate. In conclusion, prior exercise significantly increases whole-body fat oxidation during submaximal exercise compared with overnight fasting. Already high rates of maximal fat oxidation in elite endurance athletes were increased by approximately 75% after prior exercise and fasting recovery.
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| 15. |
- Hawke, Emma, et al.
(författare)
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Acidosis and cell signalling
- 2009
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Ingår i: Proceedings of 14th International Biochemistry of Exercise Conference, Muscles as Molecular and Metabolic Machines. Guelph, Canada. Appl Physiol Nutr Metab 2009 Jun 34(3):307-492. - Canadian Science Publishing (NRC Research Press) : Canadian Science Publishing. ; , s. 307-492-
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Konferensbidrag (refereegranskat)
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| 16. |
- Huang, Terry T-K, et al.
(författare)
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Metabolic syndrome in youth : current issues and challenges.
- 2007
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Ingår i: Appl Physiol Nutr Metab. - : Canadian Science Publishing. - 1715-5312. ; 32:1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- The current paper reviews the important issues and challenges facing children and adolescents with the metabolic syndrome (MetS). Studies suggest that the MetS and its risk components may be on the rise in children along with rising rates of obesity; however, further study remains warranted. The topics reviewed encompass the definition of the syndrome, its prevalence, clustering and tracking of metabolic risk factors, the role of physical activity and diet in the development of the MetS, criticisms and utility of the MetS definition, and special considerations needed in the pediatric population. Physical activity and diet may play important roles in the MetS; however, research with precise measurements of activity, diet, and metabolic outcomes is needed. The paper concludes by emphasizing that regardless of one’s position in the ongoing debate about the MetS, the long-term risks attributable to each individual risk component are real. The abnormality of one component should automatically prompt the screening of other components. Among children and adolescents, lifestyle modification should always serve as the frontline strategy. Prevention during childhood is key to the largest possible impact on adult health at the population level.
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| 17. |
- Keramidas, Michail E., et al.
(författare)
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Prolonged physical inactivity leads to a drop in toe skin temperature during local cold stress
- 2014
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 39:3, s. 369-374
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to examine the effects of a prolonged period of recumbency on the toe temperature responses during cold-water foot immersion. Ten healthy males underwent 35 days of horizontal bed rest. The right foot of the subjects was assigned as the experimental (EXP) foot. To prevent bed rest-induced vascular deconditioning in the left control foot (CON), a sub-atmospheric vascular pressure countermeasure regimen was applied on the left lower leg for 4 x 10 min every second day. On the first (BR-1) and the last (BR-35) day of the bed rest, subjects performed two 30 min foot immersion tests in 8 degrees C water, one with the EXP foot and the other with the CON foot. The tests were conducted in counter-balanced order and separated by at least a 15 min interval. At BR-35, the average skin temperature of the EXP foot was lower than at BR-1 (-0.8 degrees C; P = 0.05), a drop that was especially pronounced in the big toe (-1.6 degrees C; P = 0.05). In the CON foot, the average skin temperature decreased by 0.6 degrees C in BR-35, albeit the reduction was not statistically significant (P = 0.16). Moreover, the pressure countermeasure regimen ameliorated immersion-induced thermal discomfort for the CON foot (P = 0.05). Present findings suggest that severe physical inactivity exaggerates the drop in toe skin temperature during local cold stress, and thus might constitute a potential risk factor for local cold injury.
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| 18. |
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| 19. |
- Krite Svanberg, Emilie, et al.
(författare)
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Physiological influence of basic perturbations assessed by non-invasive optical techniques in humans
- 2011
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5320 .- 1715-5312. ; 36:6, s. 946-957
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Tidskriftsartikel (refereegranskat)abstract
- New non-invasive techniques enabling frequent or continuous assessments of various pathophysiological conditions might be used to improve in-hospital outcome by enabling earlier and more reliable bedside detection of medical deterioration. In this preclinical study, three modern non-invasive optical techniques, laser Doppler imaging (LDI), near-infrared spectroscopy (NIRS), and tissue viability imaging (TVI), were all evaluated with respect to the influence of basic physiological perturbations (including local changes in arm positioning, skin temperature, and regional blood flow conditions) on quasi simultaneously obtained values of skin perfusion, muscle tissue oxygenation (StO2), and skin blood volume, recorded in eighteen healthy volunteers. Skin perfusion measured by LDI responded prominently to changes in positioning of the arm, whereas muscle StO2 measured by NIRS did not change significantly. Total haemoglobin count (HbT) measured by NIRS and blood volume estimated by TVI both increased significantly on lowering of the limb. On local cooling, the perfusion and blood volume were both found to increase considerably, while StO2 and HbT did not change. Local heating induced a more than 10-fold increase in skin perfusion and a small increase in blood volume. On progressive venoarterial occlusion, the perfusion, StO2, HbT, and blood volume values decreased, after transient increases in HbT and blood volume before full arterial occlusion occurred, and all values approached the baseline level on release of the occlusion with a slight overshoot of the StO2. The results obtained have potential bearing on future utilization of these non-invasive techniques in the management of severely injured and (or) critically ill patients.
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| 20. |
- Lundberg, TR, et al.
(författare)
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Regional and muscle-specific adaptations in knee extensor hypertrophy using flywheel versus conventional weight-stack resistance exercise
- 2019
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. - : Canadian Science Publishing. - 1715-5320. ; 44:8, s. 827-833
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Tidskriftsartikel (refereegranskat)abstract
- This study compared the effects of the most frequently employed protocols of flywheel (FW) versus weight-stack (WS) resistance exercise (RE) on regional and muscle-specific adaptations of the knee extensors. Sixteen men (n = 8) and women (n = 8) performed 8 weeks (2–3 days/week) of knee extension RE employing FW technology on 1 leg (4 × 7 repetitions), while the contralateral leg performed regular WS training (4 × 8–12 repetitions). Maximal strength (1-repetition maximum (1RM) in WS) and peak FW power were determined before and after training for both legs. Partial muscle volume of vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF) were measured using magnetic resonance imaging. Additionally, quadriceps cross-sectional area was assessed at a proximal and a distal site. There were no differences (P > 0.05) between FW versus WS in muscle hypertrophy of the quadriceps femoris (8% vs. 9%), VL (10% vs. 11%), VM (6% vs. 8%), VI (5% vs. 5%), or RF (17% vs. 17%). Muscle hypertrophy tended (P = 0.09) to be greater at the distal compared with the proximal site, but there was no interaction with exercise method. Increases in 1RM and FW peak power were similar across legs, yet the increase in 1RM was greater in men (31%) than in women (20%). These findings suggest that FW and WS training induces comparable muscle-specific hypertrophy of the knee extensors. Given that these robust muscular adaptations were brought about with markedly fewer repetitions in the FW compared with WS, it seems FW training can be recommended as a particularly time-efficient exercise paradigm.
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| 21. |
- McGawley, Kerry, 1978-, et al.
(författare)
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Ingesting a high-dose carbohydrate solution during the cycle section of a simulated Olympic-distance triathlon improves subsequent run performance
- 2012
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 37:4, s. 664-671
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Tidskriftsartikel (refereegranskat)abstract
- The well-established ergogenic benefit of ingesting carbohydrates during single-discipline endurance sports has only been tested once within an Olympic-distance (OD) triathlon. The aim of the present study was to compare the effect of ingesting a 2:1 maltodextrin/fructose solution with a placebo on simulated OD triathlon performance. Six male and 4 female amateur triathletes (age, 25 ± 7 years; body mass, 66.8 ± 9.2 kg; peak oxygen uptake, 4.2 ± 0.6 L·min–1) completed a 1500-m swim time-trial and an incremental cycle test to determine peak oxygen uptake before performing 2 simulated OD triathlons. The swim and cycle sections of the main trials were of fixed intensities, while the run section was completed as a time-trial. Two minutes prior to completing every quarter of the cycle participants consumed 202 ± 20 mL of either a solution containing 1.2 g·min–1 of maltodextrin plus 0.6 g·min–1 of fructose at 14.4% concentration (CHO) or a sugar-free, fruit-flavored drink (PLA). The time-trial was 4.0% ± 1.3% faster during the CHO versus PLA trial, with run times of 38:43 ± 1:10 min:s and 40:22 ± 1:18 min:s, respectively (p = 0.010). Blood glucose concentrations were higher in the CHO versus PLA trial (p < 0.001), while perceived stomach upset did not differ between trials (p = 0.555). The current findings show that a 2:1 maltodextrin/fructose solution (1.8 g·min–1 at 14.4%) ingested throughout the cycle section of a simulated OD triathlon enhances subsequent 10-km run performance in triathletes.
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| 22. |
- Metcalfe, RS, et al.
(författare)
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Changes in aerobic capacity and glycaemic control in response to reduced-exertion high-intensity interval training (REHIT) are not different between sedentary men and women
- 2016
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. - : Canadian Science Publishing. - 1715-5320. ; 41:11, s. 1117-1123
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Tidskriftsartikel (refereegranskat)abstract
- Previously it has been reported that reduced-exertion high-intensity interval training (REHIT; total training time of 3 × 10 min per week) improves maximal aerobic capacity in both sedentary men and women, but improves insulin sensitivity in men only. The aim of the present study was to determine whether there is a true sex difference in response to REHIT, or that these findings can be explained by the large interindividual variability in response inherent to all exercise training. Thirty-five sedentary participants (18 women; mean ± SD age for men and women, respectively: age, 33 ± 9 and 36 ± 9 years; body mass index, 25.1 ± 2.1 and 24.1 ± 3.5 kg·m−2; maximal aerobic capacity, 38.6 ± 8.3 and 31.6 ± 4.6 mL·kg−1·min−1) completed a 6-week REHIT programme consisting of eighteen 10-min unloaded cycling sessions with 1 (first session) or 2 (all other sessions) “all-out” 10–20-s sprints against a resistance of 5% of body mass. Maximal aerobic capacity and oral glucose tolerance test-derived insulin sensitivity were determined before and after training. REHIT was associated with an increase in maximal aerobic capacity (2.54 ± 0.65 vs. 2.78 ± 0.68 L·min−1, main effect of time: p < 0.01), a trend toward reduced plasma insulin area-under-the-curve (AUC; 6.7 ± 4.8 vs. 6.1 ± 4.0 IU·min−1·mL−1, p = 0.096), but no significant change in plasma glucose AUC or the Cederholm index of insulin sensitivity. Substantial interindividual variability in response to REHIT was observed for all variables, but there was no significant effect of sex. In conclusion, REHIT improves the key health marker of aerobic capacity within a minimal total training time-commitment. There is large interindividual variability in responses to REHIT, but sex differences in the responses are not apparent.
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| 23. |
- Moberg, Marcus, et al.
(författare)
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Absence of leucine in an essential amino acid supplement reduces activation of mTORC1 signalling following resistance exercise in young females.
- 2014
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 39:2, s. 183-94
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study was to investigate the specific effect of leucine on mTORC1 signalling and amino acid metabolism in connection with resistance exercise. Comparisons were made between ingestion of supplements with and without leucine. Eight young women performed leg press exercise on 2 occasions. In randomized order they received either an aqueous solution of essential amino acids with leucine (EAA) or without leucine (EAA-Leu), given as small boluses throughout the experiment. Muscle biopsies were taken after an overnight fast before exercise and 1 and 3 h postexercise and samples of blood were taken repeatedly during the experiment. Plasma and muscle concentrations of leucine rose 60%-140% (p < 0.05) with EAA and fell 35%-45% (p < 0.05) with the EAA-Leu supplement. In the EAA-trial, plasma and muscle levels of tyrosine (not present in the supplement) and the sum of the EAA were 15%-25% (p < 0.05) lower during recovery. Phosphorylation of mTOR and p70S6k was elevated to a larger extent following 1 h of recovery with leucine in the supplement (120% vs. 49% (p < 0.05) and 59- vs. 8-fold (p < 0.05) for EAA and EAA-Leu, respectively). The levels of MAFbx and MuRF-1 mRNA and of the corresponding proteins were not significantly altered after 3 h recovery from exercise. In conclusion, the presence of leucine in the supplement enhances the stimulatory effect on mTORC1 signalling and reduces the level of tyrosine and the sum of the EAA in muscle and plasma, suggesting a stimulation of protein synthesis and (or) inhibition of breakdown, leading to improvement in net protein balance.
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| 24. |
- Mourot, L., et al.
(författare)
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Impact of the initial classic section during a simulated cross-country skiing skiathlon on the cardiopulmonary responses during the subsequent period of skate skiing
- 2014
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5320 .- 1715-5312. ; 39:8, s. 911-919
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess potential changes in the performance and cardiorespiratory responses of elite cross-country skiers following transition from the classic (CL) to the skating (SK) technique during a simulated skiathlon. Eight elite male skiers performed two 6 km (2 × 3 km) roller-skiing time trials on a treadmill at racing speed: one starting with the classic and switching to the skating technique (CL1-SK2) and another employing the skating technique throughout (SK1-SK2), with continuous monitoring of gas exchanges, heart rates, and kinematics (video). The overall performance times in the CL1-SK2 (21:12 ± 1:24) and SK1-SK2 (20:48 ± 2:00) trials were similar, and during the second section of each performance times and overall cardiopulmonary responses were also comparable. However, in comparison with SK1-SK2, the CL1-SK2 trial involved significantly higher increases in minute ventilation (VE, 89.8 ± 26.8 vs. 106.8 ± 17.6 L·min-1) and oxygen uptake (VO2; 3.1 ± 0.8 vs 3.5 ±0.5 L·min-1) 2 min after the transition as well as longer time constants for VE, VO2, and heart rate during the first 3 min after the transition. This higher cardiopulmonary exertion was associated with ~3% faster cycle rates. In conclusion, overall performance during the 2 time trials did not differ. The similar performance times during the second sections were achieved with comparable mean cardiopulmonary responses. However, the observation that during the initial 3-min post-transition following classic skiing cardiopulmonary responses and cycle rates were slightly higher supports the conclusion that an initial section of classic skiing exerts an impact on performance during a subsequent section of skate skiing.
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| 25. |
- Nielsen, Joachim, et al.
(författare)
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Physiological aspects of the subcellular localization of glycogen in skeletal muscle
- 2013
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 38:2, s. 91-99
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Forskningsöversikt (refereegranskat)abstract
- Glucose is stored in skeletal muscle fibers as glycogen, a branched-chain polymer observed in electron microscopy images as roughly spherical particles (known asβ-particles of 10-45 nm in diameter),which are distributed in distinct localizations within the myofibers and are physically associated with metabolic and scaffolding proteins. Although the subcellular localization of glycogen has been recognized for more than 40 years, the physiological role of the distinct localizations has received sparse attention. Recently, however, studies involving stereological, unbiased, quantitative methods have investigated the role and regulation of these distinct deposits of glycogen. In this report, we review the available literature regarding the subcellular localization of glycogen in skeletal muscle as investigated by electron microscopy studies and put this into perspective in terms of the architectural, topological, and dynamic organization of skeletal muscle fibers. In summary, the distribution of glycogen within skeletal muscle fibers has been shown to depend on the fiber phenotype, individual training status, short-term immobilization, and exercise and to influence both muscle contractility and fatigability. Based on all these data, the available literature strongly indicates that the subcellular localization of glycogen has to be taken into consideration to fully understand and appreciate the role and regulation of glycogen metabolism and signaling in skeletal muscle. A full understanding of these phenomena may prove vital in elucidating the mechanisms that integrate basic cellular events with changing glycogen content.
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| 26. |
- Oskarsson, Johanna, et al.
(författare)
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No individual or combined effects of caffeine and beetroot-juice supplementation during submaximal or maximal running
- 2018
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5312 .- 1715-5320. ; 43:7, s. 697-703
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dietary supplements such as caffeine and beetroot juice are used byathletes in an attempt to optimize performance and therefore gain an advantagein competition. Aim: To investigatethe individual and combined effects of caffeine and beetroot-juicesupplementation during submaximal and maximal treadmill running. Methods: Seven males (VO2max:59.0 ± 2.9 mL/kg/min) and two females (VO2max: 53.1 ± 11.4 mL/kg/min)performed a preliminary trial followed by four experimental test sessions,which consisted of two, 5-min submaximal running bouts (at ~ 70% and 80% of VO2max) and a maximal 1-km time-trial (TT) in a laboratory. Participants ingested a 70-ml dose of concentrated beetroot juice containing either 7.3 mmol of nitrate (BR) or no nitrate (PBR) 2.5 hours prior to each test session, theneither 4.8 ± 0.4 (4.3–5.6) mg/kg caffeine (C) or a caffeine placebo (PC)45 minutes before each test session. The four test sessions (BR-C, BR-PC,PBR-C and PBR-PC) were presented in a counter-balancedand double-blind manner. Results: Nosignificant differences were identified between the four interventionsregarding relative VO2, running economy, RER, heart rate (HR) or RPEat the two submaximal intensities (P > 0.05). Moreover, there were nosignificant differences in performance, maximum HR, peak blood lactateconcentration or RPE during the maximal TT when comparing the interventions (P> 0.05). Conclusion: No beneficialeffects of supplementing with typical doses of caffeine, beetroot juice or acombination of the two were observed for physiological, perceptual orperformance responses during submaximal or maximal treadmill running exercise.
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| 27. |
- Sahlin, Kent
(författare)
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Control of lipid oxidation at the mitochondrial level.
- 2009
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme. - : Canadian Science Publishing. - 1715-5312. ; 34:3, s. 382-8
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Tidskriftsartikel (refereegranskat)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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| 28. |
- Stellingwerff, T., et al.
(författare)
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The effect of acute dark chocolate consumption on carbohydrate metabolism and performance during rest and exercise
- 2014
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Ingår i: Applied Physiology, Nutrition and Metabolism. - : Canadian Science Publishing. - 1715-5320 .- 1715-5312. ; 39:2, s. 173-182
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Tidskriftsartikel (refereegranskat)abstract
- Consumption of cocoa-enriched dark chocolate (DC) has been shown to alter glucose and insulin concentration during rest and exercise compared with cocoa-depleted control (CON). However, the impact of DC consumption on exercise metabolism and performance is uncertain. Therefore, we investigated carbohydrate metabolism via stable isotope tracer techniques during exercise after subjects ingested either DC or CON. Sixteen overnight-fasted male cyclists performed a single-blinded, randomized, crossover design trial, after consuming either DC or CON at 2 h prior to 2.5 h of steady-state (SS) exercise (similar to 45% peak oxygen uptake). This was followed by an similar to 15-min time-trial (TT) and 60 min of recovery. [6,6-H-2(2)] Glucose and [U-C-13]glucose were infused during SS to assess glucose rate of appearance (R-a) and disappearance (R-d). After DC consumption, plasma (-)-glucose and insulin concentrations were significantly (p
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| 29. |
- Tryfonos, A, et al.
(författare)
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Post-exercise endothelial function is not associated with extracellular vesicle release in healthy young males
- 2023
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Ingår i: Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. - : Canadian Science Publishing. - 1715-5320. ; 48:2, s. 209-218
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Tidskriftsartikel (refereegranskat)abstract
- Acute exercise can result in temporary decrease in endothelial functions, which may represent a transient period of risk. Numerous mechanisms underpinning these responses included release of extracellular vesicles (EVs) derived from apoptotic or activated endothelial cells and platelets. This study aims to compare the time course of endothelial responses to moderate-intensity continuous exercise (MICE) and high-intensity interval exercise (HIIE) and the associations with EV release. Eighteen young healthy males (age: 22.6 ± 3.7 years, BMI: 25.6 ± 2.5 m2/kg, and VO2peak: 38.6 ± 6.5 mL/kg/min) completed two randomly assigned exercises: HIIE (10 × 1 min-@-90% heart rate reserve (HRR) and 1 min passive recovery) and MICE (30 min-@-70% HRR) on a cycle ergometer. Flow-mediated dilation (FMD) was used to assess endothelial function and blood samples were collected to evaluate endothelial cell-derived EV (CD62E+) and platelet-derived EV (CD41a+), 10, 60, and 120 min before and after exercise. There were similar increases but different time courses ( P = 0.017) in FMD (increased 10 min post-HIIE, P < 0.0001 and 60 min post-MICE, P = 0.038). CD62E+ remained unchanged ( P = 0.530), whereas overall CD41a+ release was reduced 60 min post-exercise ( P = 0.040). FMD was not associated with EV absolute release or change ( P > 0.05). Acute exercise resulted in similar improvements, but different time course in FMD following either exercise. Whilst EVs were not associated with FMD, the reduction in platelet-derived EVs may represent a protective mechanism following acute exercise.
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| 30. |
- Williams, Craig, et al.
(författare)
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Critical power in adolescent boys and girls – an exploratory study
- 2008
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Ingår i: Applied Physiology, Nutrition and Metabolism. - 1715-5312 .- 1715-5320. ; 33:6, s. 1105-1111
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study was to identify critical power (CP) in boys and girls and to examine the physiological responses to exercise at and 10% above CP (CP+10%) in a sub-group of boys. Nine boys and 9 girls (mean age 12.3 (0.5) y performed 3 constant-load tests to derive CP. Eight of the boys then exercised, in random order, at CP and CP+10% until volitional exhaustion. CP was 123 (28) and 91 (26) W for boys and girls, respectively (p < 0.02), which was equivalent to 75 (6) and 72 (10) % of peak oxygen uptake, respectively (p > 0.47). Boys' time to exhaustion at CP was 18 min 37 s (4 min 13 s), which was significantly longer (p < 0.007) than that at CP+10% (9 min 42 s (2 min 31 s)). End-exercise values for blood lactate concentration (B[La]) and maximal oxygen uptake were higher in the CP+10% trial (5.0 (2.4) mmol·L-1 and 2.15 (0.4) L·min-1, respectively) than in the CP trial, (B[La], 4.7 (2.1) mmol·L-1; maximal oxygen uptake, 2.05 (0.35) L·min-1; p > 0.13). Peak oxygen uptake (expressed as a percentage of the peak value) was not attained at the end of the trials (94 (12) and 98 (14) % for CP and CP+10%, respectively). These results provide information about the boundary between the heavy and severe exercise intensity domains in children, and have demonstrated that CP in a group of boys does not represent a sustainable steady-state intensity of exercise.
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| 31. |
- Vaag, Allan, et al.
(författare)
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Non-obese patients with type 2 diabetes and prediabetic subjects: distinct phenotypes requiring special diabetes treatment and (or) prevention?
- 2007
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Ingår i: Applied Physiology, Nutrition and Metabolism. - 1715-5320. ; 32:5, s. 912-920
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Tidskriftsartikel (refereegranskat)abstract
- A major reason for the increased incidence of type 2 diabetes mellitus (T2DM) across the world is the so-called obesity epidemic, which occurs both in developed and developing countries. However, a large proportion of patients with T2DM in European and, in particular, Asian countries are non-obese. The non-obese T2DM phenotype is characterized by disproportionally reduced insulin secretion and less insulin resistance, as compared with obese patients with T2DM. Importantly, non-obese patients with T2DM have a similar increased risk of cardiovascular disease as obese T2DM patients. The risk of T2DM in non-obese patients is influenced by genetics as well as factors operating in utero indicated by low birth weight. Furthermore, this phenotype is slightly more prevalent among patients with latent autoimmune diabetes in adults, characterized by positive anti-GAD antibodies. The recently identified TCF7L2 gene polymorphism resulting in low insulin secretion influences the risk of T2DM in both obese and non-obese subjects, but is relatively more prevalent among non-obese patients with T2DM. Furthermore, the Prol2Ala polymorphism of the PPAR-gamma gene influencing insulin action increases the risk of T2DM in non-obese subjects. Despite a "normal" body mass index, non-obese patients with T2DM are generally characterized by a higher degree of both abdominal and total fat masses (adiposity). Prevention of T2DM with lifestyle intervention is at least as effective in non-obese as in obese prediabetic subjects, and recent data suggest that metformin treatment targeting insulin resistance and non-glycemic cardiovascular disease risk factors is as beneficial in non-obese as in obese patients with T2DM. Nevertheless, non-obese patients with T2DM may progress to insulin treatment more rapidly as compared with obese patients with T2DM.
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