School for Nutrition
School for Nutrition
Sanders D.,Newman University |
Heijboer M.,Team LottoNLJumbo Professional Cycling Team |
Akubat I.,Newman University |
Meijer K.,School for Nutrition |
Hesselink M.K.,School for Nutrition
International Journal of Sports Physiology and Performance | Year: 2017
Purpose: To assess if short-duration (5 to ~300 s) high-power performance can accurately be predicted using the anaerobic power reserve (APR) model in professional cyclists. Methods: Data from 4 professional cyclists from a World Tour cycling team were used. Using the maximal aerobic power, sprint peak power output, and an exponential constant describing the decrement in power over time, a power-duration relationship was established for each participant. To test the predictive accuracy of the model, several all-out field trials of different durations were performed by each cyclist. The power output achieved during the all-out trials was compared with the predicted power output by the APR model. Results: The power output predicted by the model showed very large to nearly perfect correlations to the actual power output obtained during the all-out trials for each cyclist (r = .88 ± .21, .92 ± .17, .95 ± .13, and .97 ± .09). Power output during the all-out trials remained within an average of 6.6% (53 W) of the predicted power output by the model. Conclusions: This preliminary pilot study presents 4 case studies on the applicability of the APR model in professional cyclists using a field-based approach. The decrement in all-out performance during high-intensity exercise seems to conform to a general relationship with a single exponential-decay model describing the decrement in power vs increasing duration. These results are in line with previous studies using the APR model to predict performance during brief all-out trials. Future research should evaluate the APR model with a larger sample size of elite cyclists. © 2017 Human Kinetics, Inc.
Annegarn J.,School for Nutrition |
Meijer K.,School for Nutrition
Chest | Year: 2012
Background: Generally, the use of a rollator improves mobility in patients with COPD. Nevertheless, not all patients benefit from its use, and many patients feel embarrassed about using it. Therefore, other walking aids are worthwhile to consider. We compared the direct effects of a "new" ambulation aid (a modern draisine) with the effects of a rollator on 6-min walk distance (6MWD) in patients with COPD. Methods: Twenty-one patients with COPD performed two 6-min walk tests (6MWTs) during prerehabilitation assessment (best 6MWD: 369 ± 88 m). Additionally, two extra 6MWTs were performed on two consecutive days in random order: one time with a rollator and one time with a modern draisine. Walking pattern (n = 21) was determined using an accelerometer, and metabolic requirements (n = 10) were assessed using a mobile oxycon. Results: Walking with the modern draisine resulted in a higher 6MWD compared with walking with the rollator (466 ± 189 m vs 383 ± 85 m). Moreover, patients had fewer strides (245 ± 61 vs 300 ± 49) and a greater stride length (1.89 ± 0.73 m vs 1.27 ± 0.14 m) using the modern draisine compared with the rollator (all P ≤ .001). Oxygen uptake, ventilation, heart rate, oxygen saturation, and Borg symptom scores were comparable between both walking aids. Ten percent of the patients felt embarrassed using the modern draisine compared with 19% for the rollator, and a significantly smaller proportion of patients would use the modern draisine in daily life. Conclusions: The mean difference in 6MWD between a modern draisine and a rollator seems clinically relevant, with the same metabolic requirements and symptom Borg scores. Therefore, this "new" ambulation aid could be a good alternative to the rollator to improve functional exercise performance in patients with COPD. Trial registry: The Netherlands National Trial Registry; No.: NTR1542; URL: www.trialregister.nl. © 2012 American College of Chest Physicians.
Vanhees K.,School for Nutrition
Toxicology | Year: 2011
The flavonoid quercetin is a powerful iron chelator, capable of oxidizing heme iron in hemoglobin from Fe(2+) to Fe(3+). Moreover, quercetin crosses the placenta and accumulates in the fetus. Since adaptations made by the fetus to cope with inappropriate nutrition may lead to permanent changes, a relative high intake of quercetin may have detrimental affects later in life. Therefore, we investigated the effects of maternal exposure to quercetin (302 mg/kg feed), starting from 3 days before conception until the end of gestation, on erythropoiesis and iron homeostasis at embryonic day 14.5 and in 12-week old mice. During fetal development, quercetin exposure had no effect on the erythroid lineage switch and concomitant globin switch. However, adult mice prenatally exposed to quercetin had significant increase iron storage in the liver, by upregulating iron-associated cytokine expression (hepcidin, IL-1β, IL-6 and IL-10). These long term changes in gene expression could be mediated through epigenetic modifications, as prenatal quercetin exposure resulted in a modest hypermethylation of repetitive elements. Despite the increased iron levels, oxidative stress was significantly decreased in the liver of these animals as assessed by 8-oxo-dG levels. These data suggest that prenatal quercetin exposure results in increased iron storage, while decreasing oxidative stress induced DNA damage together with a shift towards increased expression of inflammation associated cytokines in the liver at adult age. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Vijgen G.H.E.J.,Maastricht University |
Bouvy N.D.,Maastricht University |
Hoeks J.,School for Nutrition |
Wijers S.,School for Nutrition |
And 2 more authors.
Surgery for Obesity and Related Diseases | Year: 2013
Background Obesity and type 2 diabetes are associated with impaired skeletal muscle mitochondrial metabolism. As an intrinsic characteristic of an individual, skeletal muscle mitochondrial dysfunction could be a risk factor for weight gain and obesity-associated co-morbidities, such as type 2 diabetes. On the other hand, impaired skeletal muscle metabolism could be a consequence of obesity. We hypothesize that marked weight loss after bariatric surgery recovers skeletal muscle mitochondrial function. Methods Skeletal muscle mitochondrial function as assessed by high-resolution respirometry was measured in 8 morbidly obese patients (body mass index [BMI], 41.3±4.7 kg/m2; body fat, 48.3%±5.2%) before and 1 year after bariatric surgery (mean weight loss: 35.0±8.6 kg). The results were compared with a lean (BMI 22.8±1.1 kg/m2; body fat, 15.6%±4.7%) and obese (BMI 33.5±4.2 kg/m2; body fat, 34.1%±6.3%) control group. Results Before surgery, adenosine diphosphate (ADP)-stimulated (state 3) respiration on glutamate/succinate was decreased compared with lean patients (9.5±2.4 versus 15.6±4.4 O2 flux/mtDNA; P<.05). One year after surgery, mitochondrial function was comparable to that of lean controls (after weight loss, 12.3±5.5; lean, 15.6±4.4 O 2 flux/mtDNA). In addition, we observed an increased state 3 respiration on a lipid substrate after weight loss (10.0±3.2 versus 14.0±6.6 O2 flux/mtDNA; P<.05). Conclusion We conclude that impaired skeletal muscle mitochondrial function is a consequence of obesity that recovers after marked weight loss. © 2013 Published by Elsevier Inc. on behalf of American Society for Bariatric Surgery.
Vosselman M.J.,School for Nutrition |
Vijgen G.H.E.J.,Erasmus Medical Center |
Kingma B.R.M.,School for Nutrition |
Brans B.,Maastricht University |
Van Marken Lichtenbelt W.D.,School for Nutrition
PLoS ONE | Year: 2014
Introduction: Mild cold acclimation is known to increase brown adipose tissue (BAT) activity and cold-induced thermogenesis (CIT) in humans. We here tested the effect of a lifestyle with frequent exposure to extreme cold on BAT and CIT in a Dutch man known as 'the Iceman', who has multiple world records in withstanding extreme cold challenges. Furthermore, his monozygotic twin brother who has a 'normal' sedentary lifestyle without extreme cold exposures was measured. Methods: The Iceman (subject A) and his brother (subject B) were studied during mild cold (13°C) and thermoneutral conditions (31°C). Measurements included BAT activity and respiratory muscle activity by [ 18F]FDG-PET/CT imaging and energy expenditure through indirect calorimetry. In addition, body temperatures, cardiovascular parameters, skin perfusion, and thermal sensation and comfort were measured. Finally, we determined polymorphisms for uncoupling protein-1 and β3-adrenergic receptor. Results: Subjects had comparable BAT activity (A: 1144 SUV total and B: 1325 SUVtotal), within the range previously observed in young adult men. They were genotyped with the polymorphism for uncoupling protein-1 (G/G). CIT was relatively high (A: 40.1% and B: 41.9%), but unlike during our previous cold exposure tests in young adult men, here both subjects practiced a g-Tummo like breathing technique, which involves vigorous respiratory muscle activity. This was confirmed by high [18F]FDG- uptake in respiratory muscle. Conclusion: No significant differences were found between the two subjects, indicating that a lifestyle with frequent exposures to extreme cold does not seem to affect BAT activity and CIT. In both subjects, BAT was not higher compared to earlier observations, whereas CIT was very high, suggesting that g-Tummo like breathing during cold exposure may cause additional heat production by vigorous isometric respiratory muscle contraction. The results must be interpreted with caution given the low subject number and the fact that both participants practised the g-Tummo like breathing technique. © 2014 Vosselman et al.
Martens M.J.I.,School for Nutrition |
Martens M.J.I.,Maastricht University |
Born J.M.,School for Nutrition |
Lemmens S.G.T.,School for Nutrition |
And 8 more authors.
American Journal of Clinical Nutrition | Year: 2013
Background: Flexibility of food reward-related brain signaling (FRS) between food and nonfood stimuli may differ between overweight and normal-weight subjects and depend on a fasted or satiated state. Objective: The objective was to assess this flexibility in response to visual food and nonfood cues. Design: Twenty normal-weight [mean 6 SEM BMI (in kg/m2) = 22.7 6 0.2; mean 6 SEM age = 22.4 6 0.4 y] and 20 overweight (BMI = 28.1 6 0.3; age = 24.0 6 0.7 y) participants completed 2 fMRI scans. Subjects arrived in a fasted state and consumed a breakfast consisting of 20% of subject-specific energy requirements between 2 successive scans. A block paradigm and a food . nonfood contrast was used to determine FRS. Results: An overall stimulus 3 condition 3 subject group effect was observed in the anterior cingulate cortex (ACC) (P < 0.006, F(1,38) = 9.12) and right putamen (P < 0.006, F(1,38) = 9.27). In all participants, FRS decreased from the fasted to the satiated state in the cingulate (P < 0.005, t(39) = 3.15) and right prefrontal cortex (PFC) (P < 0.006, t(39) = 3.00). In the fasted state, they showed FRS in the PFC (P < 0.004, t(39) = 3.17), left insula (P < 0.009, t(39) = 2.95), right insula (P < 0.005, t(39) = 3.12), cingulate cortex (P < 0.004, t(39) = 3.21), and thalamus (P < 0.006, t(39) = 2.96). In the satiated state, FRS was limited to the left insula (P < 0.005, t(39) = 3.21), right insula (P < 0.006, t(39) = 3.04), and cingulate cortex (P < 0.005, t(39) = 3.15). Regarding subject group, in the fasted state, FRS in the ACC was more pronounced in overweight than in normal-weight subjects (P < 0.005, F(1,38) = 9.71), whereas in the satiated state, FRS was less pronounced in overweight than in normal-weight subjects in the ACC (P < 0.006, F(1,38) = 9.18) and PFC (P < 0.006, F(1,38) = 8.86), which suggests lower inhibitory control in the overweight. Conclusion: FRS was higher in the overweight in the satiated state; however, when sufficiently satiated, the overweight showed decreased inhibitory control signalling, which facilitates overeating. This trial was registered in the Dutch clinical trial register as NTR2174. © 2013 American Society for Nutrition.
Vanhees K.,School for Nutrition |
Van Schooten F.J.,School for Nutrition |
Van Waalwijk Van Doorn-Khosrovani S.B.,School for Nutrition |
Van Helden S.,School for Nutrition |
And 5 more authors.
Free Radical Biology and Medicine | Year: 2013
Maternal intake of flavonoids, known for their antioxidant properties, may affect the offspring's susceptibility to developing chronic diseases at adult age, especially those related to oxidative stress, via developmental programming. Therefore, we supplemented female mice with the flavonoids genistein and quercetin during gestation, to study their effect on the antioxidant capacity of lung and liver of adult offspring. Maternal intake of quercetin increased the expression of Nrf2 and Sod2 in fetal liver at gestational day 14.5. At adult age, in utero exposure to both flavonoids resulted in the increased expression of several enzymatic antioxidant genes, which was more pronounced in the liver than in the adult lung. Moreover, prenatal genistein exposure induced the nonenzymatic antioxidant capacity in the adult lung, partly by increasing glutathione levels. Prenatal exposure to both flavonoids resulted in significantly lower levels of oxidative stress-induced DNA damage in liver only. Our observations lead to the hypothesis that a preemptive trigger of the antioxidant defense system in utero had a persistent effect on antioxidant capacity and as a result decreased oxidative stress-induced DNA damage in the liver. © 2013 Elsevier Inc.
van der Lans A.A.J.J.,School for Nutrition |
Wierts R.,Maastricht University |
Vosselman M.J.,School for Nutrition |
Schrauwen P.,School for Nutrition |
And 2 more authors.
American Journal of Physiology - Regulatory Integrative and Comparative Physiology | Year: 2014
The relevance of functional brown adipose tissue (BAT) depots in human adults was undisputedly proven approximately seven years ago. Here we give an overview of all dedicated studies that were published on cold-induced BAT activity in adult humans that appeared since then. Different cooling protocols and imaging techniques to determine BAT activity are reviewed. BAT activation can be achieved by means of air- or water-cooling protocols. The most promising approach is individualized cooling, during which subjects are studied at the lowest temperature for nonshivering condition, probably revealing maximal nonshivering thermogenesis. The highest BAT prevalence (i.e., close to 100%) is observed using the individualized cooling protocol. Currently, the most widely used technique to study the metabolic activity of BAT is deoxy-2-[18F]fluoro-D-glucose ([18F]FDG)-positron emission tomography/computed tomography (PET/CT) imaging. Dynamic imaging provides quantitative information about glucose uptake rates, whereas static imaging reflects overall BAT glucose uptake, localization, and distribution. In general, standardized uptake values (SUV) are used to quantify BAT activity. An accurate determination of total BAT volume is hampered by the limited spatial resolution of the PET image, leading to spillover. Different research groups use different SUV threshold values, which make it difficult to directly compare BAT activity levels between studies. Another issue is the comparison of [18F]FDG uptake in BAT with respect to other tissues or upon with baseline values. This comparison can be performed by using the "fixed volume" methodology. Finally, the potential use of other relatively noninvasive methods to quantify BAT, like magnetic resonance imaging or thermography, is discussed. © 2014 the American Physiological Society.
PubMed | Newman University, School for Nutrition and University of Hull
Type: | Journal: International journal of sports physiology and performance | Year: 2017
The aim of this study was to assess the dose-response relationships between different training load methods and aerobic fitness and performance in competitive road cyclists.Training data from 15 well-trained competitive cyclists were collected during a 10-week (December - March) pre-season training period. Before and after the training period, participants underwent a laboratory incremental exercise test with gas exchange and lactate measures and a performance assessment using an 8-min time trial (8MT). Internal training load was calculated using Banisters TRIMP (bTRIMP), Edwards TRIMP (eTRIMP), individualized TRIMP (iTRIMP), Lucias TRIMP (luTRIMP) and session-RPE (sRPE). External load was measured using Training Stress Score (TSS).Large to very large relationships (r = 0.54-0.81) between training load and changes in submaximal fitness variables (power at 2 and 4 mmolLThe results show that training load quantification methods that integrate individual physiological characteristics have the strongest dose-response relationships, suggesting this to be an essential factor in the quantification of training load in cycling.
Vaes A.W.,Program Development Center |
Wouters E.F.M.,Program Development Center |
Franssen F.M.E.,Program Development Center |
Uszko-Lencer N.H.M.K.,Cardiology |
And 6 more authors.
Chest | Year: 2011
Background: Patients with COPD generally have a poor peak aerobic capacity and, therefore, may experience more inconvenience during domestic activities of daily life (ADLs). Yet, task-related oxygen uptake and symptom perception during ADLs have been studied rarely in COPD. Therefore, it remains unknown whether and to what extent differences may exist in task-related oxygen uptake and symptom perception during ADLs in patients with COPD after stratifi cation for sex; GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage; Medical Research Council (MRC) dyspnea grade; or score on the BMI, obstruction, dyspnea, exercise capacity (BODE) index. Methods: Ninety-seven patients with COPD and 20 healthy elderly subjects performed the following fi ve self-paced domestic ADLs with 4-min rest intervals: putting on socks, shoes, and vest; folding eight towels; putting away groceries; washing four dishes, cups, and saucers; and sweeping the fl oor for 4 min. Task-related oxygen uptake was assessed using an Oxycon Mobile device, whereas Borg scores were used to assess task-related dyspnea and fatigue. Results: Patients with COPD used a signifi cantly higher proportion of their peak aerobic capacity and ventilation to perform ADLs than did the healthy subjects, accompanied by higher taskrelated Borg dyspnea scores. Patients with GOLD stage IV, MRC dyspnea grade 5, or BODE score ≥ 6 points had the highest task-related oxygen uptake and dyspnea perception during the performance of domestic ADLs. Results showed no sex-related differences. Conclusion: Patients with COPD experience a relatively high metabolic load and symptom perception during the performance of ADLs that is not the same as seen in their healthy peers, particularly in patients with GOLD stage IV, MRC dyspnea grade 5, or BODE score ≥ 6 points. © 2011 American College of Chest Physicians.