Measurement Of Oxygen Uptake Research Articles

Inertial sensors to estimate the energy expenditure of team-sport athletes.

To quantify the energy expenditure of Australian Football training and matches and the total daily energy expenditure of Australian Football players using tri-axial accelerometers. Cross sectional observation study. An algorithm was developed for the MiniMax 4.0 (Catapult Innovations, Scoresby Australia) using measured oxygen uptake and accelerometer data to estimate energy expenditure of 18 Australian Football players during training and matches. The algorithm was used to validate a metabolic power calculation used by Catapult Innovations (Scoresby Australia) in their proprietary GPS software. The SenseWear™ (Model MF-SW, Bodymedia, Pittsburgh, PA) armband was used to determine non-exercise activity thermogenesis and was worn for 7 days leading into a match. Training, match and non-exercise activity thermogenesis data was summed for total daily energy expenditure. Energy expenditure for field training was estimated to be 2719±666kJ and for matches to be 5745±1468kJ. The estimated energy expenditure in the current study showed a large correlation (r=0.57, 90% CI 0.06-0.84) with the metabolic power calculation. The mean total daily energy expenditure for an in-season main training day was approximately 18,504kJ and match day approximately 19,160kJ with non-exercise activity thermogenesis contributing approximately 85% and 69% on training and match days, respectively. The MiniMax 4.0 and SenseWear™ armband accelerometers provide a practical, non-invasive and an effective method to successfully measure training and match energy expenditure, and non-exercise activity thermogenesis in field sport athletes. Taking methodological limitations into consideration, measuring energy expenditure allows for individualised nutrition programming to enhance performance and achieve body composition goals.

Applicability of fluorescence-based sensors to the determination of kinetic parameters for O2 in oxygenases

Optical methods for O2 determination based on dynamic fluorescence quenching have been applied to measure oxygen uptake rates in cell culture and to determine intracellular oxygen levels. Here we demonstrate the applicability of fluorescence-based probes in determining kinetic parameters for O2 using as an example catalysis by a cofactor-independent oxygenase (DpgC). Fluorescence-based sensors provide a direct assessment of enzyme-catalyzed O2 consumption using commercially available, low-cost instrumentation that is easily customizable and, thus, constitutes a convenient alternative to the widely used Clark-type electrode, especially in cases where chemical interference is expected to be problematic.

Heart rate and oxygen demand of powered exoskeleton-assisted walking in persons with paraplegia.

Historically, persons with paralysis have limited options for overground ambulation. Recently, powered exoskeletons have become available, which are systems that translate the user's body movements to activate motors to move the lower limbs through a predetermined gait pattern. As part of an ongoing clinical study (NCT01454570), eight nonambulatory persons with paraplegia were trained to ambulate with a powered exoskeleton. Measurements of oxygen uptake (VO2) and heart rate (HR) were recorded for 6 min each during each maneuver while sitting, standing, and walking. The average value of VO2 during walking (11.2 +/- 1.7 mL/kg/min) was significantly higher than those for sitting and standing (3.5 +/- 0.4 and 4.3 +/- 0.9 mL/kg/min, respectively; p < 0.001). The HR response during walking was significantly greater than that of either sitting or standing (118 +/- 21vs 70 +/- 10 and 81 +/- 12 beats per minute, respectively: p < 0.001). Persons with paraplegia were able to ambulate efficiently using the powered exoskeleton for overground ambulation, providing potential for functional gain and improved fitness. ClinicalTrials.gov; NCT01454570; "The ReWalk Exoskeletal Walking System for Persons with Paraplegia (VA_ReWalk)"; https://clinicaltrials.gov/ct2/show/NCT01454570.

Technical note: Comparison of two methods to quantify exercise energy expenditure in trotters

This study aimed at quantifying energy expenditure during 4 specific training exercises, that is, promenade, jogging, parcours, and interval exercises, using field measurements of oxygen consumption and heart rate in trotters. Six animals performed 2 preliminary tests to determine their individual maximum velocity and to establish their individual oxygen consumption/heart rate relationship from an incremental test. Then, they undertook each of the 4 specific exercises separated by 1 wk to avoid fatigue. The intensity of the 4 exercises was expressed in percent of individual maximum velocity as well as duration and distance set according to current training practices of French trotter trainers. Throughout the incremental test and the 4 exercises, oxygen consumption and heart rate were continuously recorded using a portable respiratory gas analyzer. Energy expenditure of the 3 different phases (warm-up, exercise, and recovery) of the 4 exercises and the total energy expended during exercises (sum of energy expended during the 3 phases) were calculated from direct oxygen uptake measurements and from estimated oxygen uptake using heart rate and O caloric equivalent. The quantification of total energy expenditure from the 2 methods was not significantly different. However, estimated energy expenditure was significantly lower from estimated oxygen consumption than direct oxygen uptake method concerning the warm-up and exercise phase of parcours. Our results indicate that the estimated oxygen uptake from heart rate measurements could be used to evaluate total energy expenditure of exercises in trotters. Whereas this method requires previous establishment of an individual oxygen consumption/heart rate curve, it is easy to record using commercially available instruments under practical conditions and opens new perspectives to assess energy balance in trotters' nutrition.

Srovnání ekonomiky běhu na základě příjmu kyslíku u vytrvalostních běžců na asfaltu, škváře a tartanu

The purpose of this study was to compare running economy (by oxygen consumption) in long distance runners on three different surfaces (asphalt, cinder and tartan). Thirty Czech long distance runners (age: 25.1±4.3 years, height: 183.2±7.4 cm, body mass: 72.4±6.0 kg, BMI: 22.5±1.4 and VO2 max: 65.8±5.2 ml∙min∙kg-1) participated in this study. We measured oxygen uptake by wireless, portable cardiopulmonary stress testing system (Oxygen Mobile, Viasys) on each surface during running at speeds: 10, 12, 14 and 16 km∙h-1. Differences of oxygen uptake were assessed statistically using parametric ANOVA and post-hoc Tukey HSD test. We found significant differences between asphalt and cinder for 12, 14 and 16 km∙h-1. Differences of average values of oxygen uptake on tartan at 10 km∙h-1:35.2±2.8 ml∙min∙kg-1; 12 km∙h-1: 41.0±3.4 ml∙min∙kg-1; 14 km∙h-1: 47.8±4.2 ml∙min∙kg-1a 16 km∙h-1: 54.2±4.9 ml∙min∙kg-1; on cinder at 10 km∙h-1: 36.2±3.6 ml∙min∙kg-1; 12 km∙h-1: 42.5±3.9 ml∙min∙kg-1; 14 km∙h-1: 49.5±5.4 ml∙min∙kg-1a 16 km∙h-1: 56.1±6.8 ml∙min∙kg-1 and on asphalt at 10 km∙h-1: 35.0±3.7 ml∙min∙- kg-1; 12 km∙h-1: 39.8±4.0 ml∙min∙kg-1; 14 km∙h-1: 46.3±5.1 ml∙min∙kg-1a 16 km∙h-1 : 53.5±4.8 ml∙min∙kg-1. The lowest values of oxygen uptake were found on asphalt surface. The asphalt is probably the most favorable surface according to energetic aspect.

In situ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2 × 1 surface by supersonic molecular oxygen beams.

In situ synchrotron radiation photoelectron spectroscopy was performed during the oxidation of the Ge(100)-2 × 1 surface induced by a molecular oxygen beam with various incident energies up to 2.2 eV from the initial to saturation coverage of surface oxides. The saturation coverage of oxygen on the clean Ge(100) surface was much lower than one monolayer and the oxidation state of Ge was +2 at most. This indicates that the Ge(100) surface is so inert toward oxidation that complete oxidation cannot be achieved with only pure oxygen (O2) gas, which is in strong contrast to Si surfaces. Two types of dissociative adsorption, trapping-mediated and direct dissociation, were confirmed by oxygen uptake measurements depending on the incident energy of O2. The direct adsorption process can be activated by increasing the translational energy, resulting in an increased population of Ge(2+) and a higher final oxygen coverage. We demonstrated that hyperthermal O2 beams remarkably promote the room-temperature oxidation with novel atomic configurations of oxides at the Ge(100) surface. Our findings will contribute to the fundamental understanding of oxygen adsorption processes at 300 K from the initial stages to saturated oxidation.

The effect of a cadence retraining protocol on running biomechanics and efficiency: a pilot study

Many studies have documented the association between mechanical deviations from normal and the presence or risk of injury. Some runners attempt to change mechanics by increasing running cadence. Previous work documented that increasing running cadence reduces deviations in mechanics tied to injury. The long-term effect of a cadence retraining intervention on running mechanics and energy expenditure is unknown. This study aimed to determine if increasing running cadence by 10% decreases running efficiency and changes kinematics and kinetics to make them less similar to those associated with injury. Additionally, this study aimed to determine if, after 6 weeks of cadence retraining, there would be carryover in kinematic and kinetic changes from an increased cadence state to a runner’s preferred running cadence without decreased running efficiency. We measured oxygen uptake, kinematic and kinetic data on six uninjured participants before and after a 6-week intervention. Increasing cadence did not result in decreased running efficiency but did result in decreases in stride length, hip adduction angle and hip abductor moment. Carryover was observed in runners’ post-intervention preferred running form as decreased hip adduction angle and vertical loading rate.

Hypoxic Training

The effects of hypoxic training on exercise performance remain controversial. Here, we tested the hypotheses that i) hypoxic training possesses ergogenic effects at sea level and altitude and ii) the benefits are primarily mediated by improved mitochondrial function of the skeletal muscle. We determined aerobic performance (incremental test to exhaustion and time trial for a set amount of work) in moderately trained subjects undergoing 6 wk of endurance training (3-4 times per week, 60 min per session) in normoxia (placebo, n = 8) or normobaric hypoxia (FIO2 = 0.15, n = 9) using a double-blind and randomized design. Exercise tests were performed in normoxia and acute hypoxia (FIO2 = 0.15). Skeletal muscle mitochondrial respiratory capacities and electron coupling efficiencies were measured via high-resolution respirometry. Total hemoglobin mass was assessed by carbon monoxide rebreathing. Skeletal muscle respiratory capacity was not altered by training or hypoxia; however, electron coupling control respective to fat oxidation slightly diminished with hypoxic training. Hypoxic training did increase total hemoglobin mass more than the placebo (8.4% vs 3.3%, P = 0.02). In normoxia, hypoxic training had no additive effect on maximal measures of oxygen uptake or time trial performance. In acute hypoxia, hypoxic training conferred no advantage on maximal oxygen uptake but tended to enhance time trial performance more than normoxic training (52% vs 32%, P = 0.09). Our data suggest that, in moderately trained subjects, 6 wk of hypoxic training possesses no ergogenic effect at sea level. It is not excluded that hypoxic training might facilitate endurance capacity at moderate altitude; however, this issue is still open and needs to be further examined.

Examination of Cardiac Rehabilitation Participants Referred to a Musculoskeletal Clinic

To describe participants in a cardiac rehabilitation program who were referred to an in-house musculoskeletal clinic and their cardiac rehabilitation and musculoskeletal outcomes. A retrospective chart review was done on 51 participants who were referred to the musculoskeletal clinic between February 1, 2009, and March 31, 2010. Data on demographics, clinical characteristics, and cardiac rehabilitation and musculoskeletal outcomes were collected. Analyses included descriptive statistics and nonparametric analysis of outcome measures. Of the 51 participants, 88.2% reported preexisting musculoskeletal conditions. The most common region of diagnosed musculoskeletal conditions included knee(s) (45.1%), back (25.5%), and shoulder(s) (17.6%). For those who attended the musculoskeletal clinic and had pre-/postintervention data (n = 14), there was a significant improvement from initial to final mean Numerical Pain Rating Scale scores (P = .001) and peak oxygen uptake measures (P = .002). A musculoskeletal clinic within a cardiac rehabilitation program could allow for musculoskeletal conditions to be addressed in an effective manner and potentially minimize their negative impact on cardiac rehabilitation participation and outcomes.

Exercise tolerance in obese vs. lean adolescents: a systematic review and meta-analysis.

To prescribe feasible and medically safe exercise interventions for obese adolescents, it remains to be determined whether exercise tolerance is altered and whether anomalous cardiopulmonary responses during maximal exercise testing are present. Studies that examined cardiopulmonary responses to maximal exercise testing in obese adolescents were searched: cardiopulmonary exercise tests with respiratory gas exchange measurements of peak oxygen uptake (VO2peak) were performed and comparisons between obese and lean adolescents were made. Study quality was assessed using a standardized item list. By meta-analyses VO2peak, peak cycling power output (Wpeak) and peak heart rate (HRpeak) were compared between groups. Nine articles were selected (333 obese vs. 145 lean adolescents). VO2peak (L min(-1)), HRpeak and Wpeak were not different between groups (P ≥ 0.10), while a trend was found for a reduced VO2peak (mL min(-1) kg(-1) lean tissue mass) (P=0.07) in obese vs. lean adolescents. It remained uncertain whether anomalous cardiopulmonary responses occur during maximal exercise testing in obese adolescents. In conclusion, a trend was found for lowered VO2peak (mL min(-1)kg(-1) lean tissue mass) in obese vs. lean adolescents. Whether cardiopulmonary anomalies during maximal exercise testing would occur in obese adolescents remains uncertain. Studies are therefore warranted to examine the cardiopulmonary response during maximal exercise testing in obese adolescents.

하수처리장의 포기조 최적 DO 농도 산정 및 공기송풍량 자동제어를 통한 에너지 절감 효과 도출

생물학적 하수처리공정에서 안정적인 방류수질 확보와 처리 비용을 적게 하는 것은 매우 중요하다. 하지만 유입수 유량 및 성분 농도의 변화와 미생물의 비선형적인 동특성, 기타 환경 요인에 의해서 최적의 운전 제어를 하기가 쉽지 않기 때문에, 기존의 하수처리장에서는 필요한 양 이상의 폭기 및 화학물질을 과량 주입하는 방법 등을 사용하였다. 본 연구에서는 포기조에서 미생물에 필요한 용존산 소농도를 유지함과 동시에 과폭기로 인한 전력 비용을 감소할 수 있는 최적 제어 방법을 제안하였다. 최적 제어를 위하여 실시간 미생물 호흡률 측정기(Oxygen uptake rate, OUR)을 이용하여 측정하였고, 실시간 호흡률 측정값을 바탕으로 현재 미생물에 필요한 최적 DO 농도를 제안하였으며, 이에 따라 공기송풍기가 자동제어될 수 있도록 구성하였다. 최적 제어 방법을 통하여 하수처리장 포기조의 공기 송풍량에 소요되는 전력비용을 절감할 수 있었다. It is important to keep stable effluent water quality and minimize operation cost in biological wastewater treatment plant. However, the optimal operation is difficult because of the change of influent flow rate and concentrations, the nonlinear dynamics of microbiology growth rate and other environmental factors. Therefore, many wastewater treatment plants are operated for much more redundant oxygen or chemical dosing than the necessary. In this study, the optimal control scheme for dissolved oxygen (DO) is suggested to prevent over-aeration and the reduction of the electric cost in plant operation while maintaining the dissolved oxygen (DO) concentration for the metabolism of microorganisms in oxic reactor. For optimal control, The oxygen uptake rate (OUR) is realtime measured for the identification of influent characterization and the identification of microorganisms' oxygen requirement in oxic reactor. Optimal DO seT-Point needed for the microorganism is suggested based on real time measurement of oxygen uptake of microorganism and the control of air blower. Therefore, both stable effluent quality and minimization of electric cost are satisfied with a suggested optimal setpoint decision system by providing the necessary oxygen supply requirement to the microorganisms coping with the variations of influent loading.

Seasonal-dependent variations in metabolic status of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids.

This study investigated seasonal changes in the metabolic performance of spermatozoa and activity of the antioxidant enzymes in the seminal plasma of three wild boar/domestic pigs (aged 1.5 to 2.5 years) and the activity of the antioxidant enzymes in fluids of the cauda epididymidis and vesicular glands from 16 wild boar/domestic pig hybrids (aged 1 to 3 years). Parameters of the sperm metabolic activity, such as total motility, mitochondrial functions, and measurements of oxygen uptake, ATP content and L-lactate production, were analyzed during the spring-summer and autumn-winter periods. Besides these sperm metabolic parameters, the sperm membrane integrity was also assessed. Total protein content and activity of the antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were measured in the reproductive tract fluids. There were no marked significant differences (P > 0.05) between the seasonal periods in terms of sperm motility, mitochondrial function and oxygen uptake; however, spermatozoa collected during the autumn-winter period exhibited higher (P < 0.05) ATP content and L-lactate production than those harvested during the spring-summer period. It was found that the vesicular gland fluid exhibited a higher level of SOD activity during the spring-summer period compared with the autumn-winter period. Furthermore, CAT activity in the seminal plasma and vesicular gland fluid was greater during the autumn-winter. Total protein content was significantly higher in the vesicular gland fluid, whereas the cauda epididymidal fluid exhibited greater SOD and GPx activities, irrespective of the seasonal period. The findings of this study confirmed seasonal-related differences in the metabolic performance of spermatozoa and activity of antioxidant enzymes of the reproductive tract of the boar/domestic pig hybrids.

최대산소섭취량 간접측정법을 활용한 청소년 비만 예측 심폐체력 절사값의 유용성

The purpose of this study was to examine usefulness of cardiorespiratory fitness cut-off value for predicting adolescent obesity using an indirect measurement of maximal oxygen uptake(VO2max). To complete this study, 2,327 students(middle and high school students: male: 1,211, female: 1,113) were tested obesity(body mass index, percent body fat) and 20m multi-stage shuttle run test for VO2max. The data were analyzed by using SPSS 17.0 and MedCalc 12.2. The cut-off values of cardiorespiratory fitness, which would predict obesity were calculated by ROC curve analysis. Also AUC(area under the ROC curve) and Interval likelihood ratio was used for examine of usefulness. The results of this study was as follows; First, cardiorespiratory fitness was inversely related to obesity, that, the higher cardiorespiratory fitness the lower obesity. Second, the maximal oxygen uptake estimated by indirect measurement of cardiorespiratory fitness cut-off values of obesity has proven useful for prediction. I think that cut-off value of predicting obesity was shown to be useful in diagnosing obesity compared to another indices.

Validation of a brief step-test protocol for estimation of peak oxygen uptake.

Physical exercise capacity has been shown to predict cardiovascular disease incidence and is increasingly measured in epidemiological studies. However, direct measurement of peak oxygen uptake is too time consuming in large-scale studies. We therefore investigated whether a brief 3-minute step-test protocol can be used to estimate peak oxygen uptake in these settings. A group of 97 subjects performed the YMCA step test and a maximal treadmill test with continuous measurement of oxygen uptake. Correlation and linear regression analyses were used to identify VO2peak predictors obtained from the step test and to develop models for VO2peak estimation. The YMCA model, including the 1-minute heart beat count, predicted VO2peak with R = 0.83. A novel simplified model based on the heart rate at 45 s of recovery performed comparable (R = 0.83). However, models based on heart rate measures were only valid in subjects who completed the test according to protocol, but not in subjects who terminated prematurely. For the applicability in subjects with low exercise capacity, a new model including gas exchange analysis enabled prediction of VO2peak (R = 0.89). All models were validated in an independent sample (r = 0.86-0.91). Exercise time of the step test was less than one-hird of standard ergospirometry (treadmill test: 654 ± 151 s, step test: 180 s, p < 0.001). In large-scale epidemiological studies with limited time slots for exercise testing and significant proportions of subjects with low exercise capacity a modified version of the YMCA step test may be used to predict VO2peak.

Assessment of Biological Kinetics in a Conventional Municipal WWTP by Means of the Oxygen Uptake Rate Method

Pollution control of surface water bodies requires stringent checks on wastewater treatment plants performances. The satisfactory operation of biological treatment, commonly performed by means of activated sludge processes, requires a number of controlling and monitoring procedures. Suitable respirometric techniques for the determination of the kinetic parameters that regulate biological processes have been implemented in order to achieve this aim. This paper describes the results of an experimental research carried out in a conventional Italian municipal wastewater treatment plant. Particularly, the research has been finalized to both evaluate the biological process for the removal of biodegradable pollutants, such as carbonaceous substrates and ammonia nitrogen, and to collect data in order to evaluate a possible plant upgrade. Heterotrophic and autotrophic biomass kinetic parameters have been examined using respirometric techniques based on oxygen uptake measurements. The research performed makes a valuable contribution toward verifying the reliability of the values proposed in the literature for some kinetic parameters, which have been commonly used for a long time.

Combustion, respiration and intermittent exercise: a theoretical perspective on oxygen uptake and energy expenditure.

While no doubt thought about for thousands of years, it was Antoine Lavoisier in the late 18th century who is largely credited with the first “modern” investigations of biological energy exchanges. From Lavoisier’s work with combustion and respiration a scientific trend emerges that extends to the present day: the world gains a credible working hypothesis but validity goes missing, often for some time, until later confirmed using proper measures. This theme is applied to glucose/glycogen metabolism where energy exchanges are depicted as conversion from one form to another and, transfer from one place to another made by both the anaerobic and aerobic biochemical pathways within working skeletal muscle, and the hypothetical quantification of these components as part of an oxygen (O2) uptake measurement. The anaerobic and aerobic energy exchange components of metabolism are represented by two different interpretations of O2 uptake: one that contains a glycolytic component (1 L O2 = 21.1 kJ) and one that does not (1 L O2 = 19.6 kJ). When energy exchange transfer and oxygen-related expenditures are applied separately to exercise and recovery periods, an increased energy cost for intermittent as compared to continuous exercise is hypothesized to be a direct result.

The effect of neoadjuvant chemotherapy on physical fitness and survival in patients undergoing oesophagogastric cancer surgery

BackgroundNeoadjuvant chemotherapy (NAC) followed by surgery for resectable oesophageal or gastric cancer improves outcome when compared with surgery alone. However NAC has adverse effects. We assess here whether NAC adversely affects physical fitness and whether such an effect is associated with impaired survival following surgery. MethodsWe prospectively studied 116 patients with oesophageal or gastric cancer to assess the effect of NAC on physical fitness, of whom 89 underwent cardiopulmonary exercise testing (CPET) before NAC and proceeded to surgery. 39 patients were tested after all cycles of NAC but prior to surgery. Physical fitness was assessed by measuring oxygen uptake (V˙O2 in ml kg−1 min−1) at the estimated lactate threshold (θˆL) and at peak exercise (V˙O2 peak in ml kg−1 min−1). ResultsV˙O2 at θˆL and at peak were significantly lower after NAC compared to pre-NAC values: V˙O2 at θˆL 14.5 ± 3.8 (baseline) vs. 12.3 ± 3.0 (post-NAC) ml kg−1 min−1; p ≤ 0.001; V˙O2 peak 20.8 ± 6.0 vs. 18.3 ± 5.1 ml kg−1 min−1; p ≤ 0.001; absolute V˙O2 (ml min−1) at θˆL and peak were also lower post-NAC; p ≤ 0.001. Decreased baseline V˙O2 at θˆL and peak were associated with increased one year mortality in patients who completed a full course of NAC and had surgery; p = 0.014. ConclusionNAC before cancer surgery significantly reduced physical fitness in the overall cohort. Lower baseline fitness was associated with reduced one-year-survival in patients completing NAC and surgery, but not in patients who did not complete NAC. It is possible that in some patients the harms of NAC may outweigh the benefits.Trials Registry Number: NCT01335555.

Effects of Individualized Exercise Training in Patients With Catecholaminergic Polymorphic Ventricular Tachycardia Type 1

Ventricular arrhythmias (VAs) in patients with catecholaminergic polymorphic ventricular tachycardia type 1 (CPVT1) are triggered at an individual and reproducible heart rate (HR) during exercise. Long-term effects of exercise on arrhythmia threshold in CPVT1 are not known. To investigate whether exercise training (ET) is feasible in patients with CPVT1, 13 patients with CPVT1 and confirmed genetic mutations performed bicycle exercise testing with maximal oxygen uptake (VO2max) measurements at baseline and after 13 weeks. The threshold HR for VA was defined as the HR when bigeminal ventricular extrasystoles or more severe VAs occurred. Six patients were enrolled in a 12-week high-intensity ergometer bicycle ET program (ET patients) with 60 min exercise sessions 3 times per week. The remaining 7 patients with CPVT1 were included as "sedentary" control (SED) patients complying with current recommendations to restrain from high-intensity physical activity. ET patients completed 28 ± 3 exercise sessions (78 ± 8% program completion) with 13 ± 3% increase in VO2max versus baseline (20.2 ± 1.6 vs 17.9 ± 1.3 ml/kg/min, p <0.05). No adverse events occurred. Baseline threshold for VA was 100 ± 6 beats/min in ET patients and 135 ± 4 beats/min in SED patients. After the training period, threshold HR for VA was 111 ± 10 beats/min in ET patients and 123 ± 6 beats/min in SED patients. The threshold for VA increased in ET compared with SED patients (+11 vs -12 beats/min, p <0.05). In conclusion, patients with CPVT1 benefitted from individualized ET with improved aerobic capacity and increased threshold HR for VA compared with SED patients.

A Healthy Brain in a Healthy Body: Brain Network Correlates of Physical and Mental Fitness

A healthy lifestyle is an important focus in today's society. The physical benefits of regular exercise are abundantly clear, but physical fitness is also associated with better cognitive performance. How these two factors together relate to characteristics of the brain is still incompletely understood. By applying mathematical concepts from ‘network theory’, insights in the organization and dynamics of brain functioning can be obtained. We test the hypothesis that neural network organization mediates the association between cardio respiratory fitness (i.e. VO2 max) and cognitive functioning. A healthy cohort was studied (n = 219, 113 women, age range 41–44 years). Subjects underwent resting-state eyes-closed magneto-encephalography (MEG). Five artifact-free epochs were analyzed and averaged in six frequency bands (delta-gamma). The phase lag index (PLI) was used as a measure of functional connectivity between all sensors. Modularity analysis was performed, and both within and between-module connectivity of each sensor was calculated. Subjects underwent a maximum oxygen uptake (VO2 max) measurement as an indicator of cardio respiratory fitness. All subjects were tested with a commonly used Dutch intelligence test. Intelligence quotient (IQ) was related to VO2 max. In addition, VO2 max was negatively associated with upper alpha and beta band modularity. Particularly increased intermodular connectivity in the beta band was associated with higher VO2 max and IQ, further indicating a benefit of more global network integration as opposed to local connections. Within-module connectivity showed a spatially varied pattern of correlation, while average connectivity did not show significant results. Mediation analysis was not significant. The occurrence of less modularity in the resting-state is associated with better cardio respiratory fitness, while having increased intermodular connectivity, as opposed to within-module connections, is related to better physical and mental fitness.

A Test of the Metabolic Cost of Cushioning Hypothesis during Unshod and Shod Running

This study aimed to investigate the effects of surface and shoe cushioning on the metabolic cost of running. In running, the leg muscles generate force to cushion the impact with the ground. External cushioning (surfaces or shoes) may reduce the muscular effort needed for cushioning and thus reduce metabolic cost. Our primary hypothesis was that the metabolic cost of unshod running would decrease with a more cushioned running surface. We also hypothesized that because of the counteracting effects of shoe cushioning and mass, unshod running on a hard surface would have approximately the same metabolic cost as running in lightweight, cushioned shoes. To test these hypotheses, we attached 10- and 20-mm-thick slats of the same foam cushioning used in running shoe midsoles to the belt of a treadmill that had a rigid deck. Twelve subjects who preferred a midfoot strike pattern and had substantial barefoot/minimalist running experience ran without shoes on the normal treadmill belt and on each thickness of foam. They also ran with lightweight, cushioned shoes on the normal belt. We collected V˙O2 and V˙CO2 to calculate the metabolic power demand and used a repeated-measures ANOVA to compare between conditions. Compared to running unshod on the normal belt, running unshod on the 10-mm-thick foam required 1.63% ± 0.67% (mean ± SD) less metabolic power (P = 0.034) but running on the 20-mm-thick foam had no significant metabolic effect. Running with and without shoes on the normal belt had similar metabolic power demands, likely because the beneficial energetic effects of cushioning counterbalanced the detrimental effects of shoe mass. On average, surface and shoe cushioning reduce the metabolic power required for submaximal running.