Douglas Bag Method Research Articles

Objective Assessment of Physical Activity at Home Using a Novel Floor-Vibration Monitoring System: Validation and Comparison With Wearable Activity Trackers and Indirect Calorimetry Measurements.

The self-monitoring of physical activity is an effective strategy for promoting active lifestyles. However, accurately assessing physical activity remains challenging in certain situations. This study evaluates a novel floor-vibration monitoring system to quantify housework-related physical activity. This study aims to assess the validity of step-count and physical behavior intensity predictions of a novel floor-vibration monitoring system in comparison with the actual number of steps and indirect calorimetry measurements. The accuracy of the predictions is also compared with that of research-grade devices (ActiGraph GT9X). The Ocha-House, located in Tokyo, serves as an independent experimental facility equipped with high-sensitivity accelerometers installed on the floor to monitor vibrations. Dedicated data processing software was developed to analyze floor-vibration signals and calculate 3 quantitative indices: floor-vibration quantity, step count, and moving distance. In total, 10 participants performed 4 different housework-related activities, wearing ActiGraph GT9X monitors on both the waist and wrist for 6 minutes each. Concurrently, floor-vibration data were collected, and the energy expenditure was measured using the Douglas bag method to determine the actual intensity of activities. Significant correlations (P<.001) were found between the quantity of floor vibrations, the estimated step count, the estimated moving distance, and the actual activity intensities. The step-count parameter extracted from the floor-vibration signal emerged as the most robust predictor (r2=0.82; P<.001). Multiple regression models incorporating several floor-vibration-extracted parameters showed a strong association with actual activity intensities (r2=0.88; P<.001). Both the step-count and intensity predictions made by the floor-vibration monitoring system exhibited greater accuracy than those of the ActiGraph monitor. Floor-vibration monitoring systems seem able to produce valid quantitative assessments of physical activity for selected housework-related activities. In the future, connected smart home systems that integrate this type of technology could be used to perform continuous and accurate evaluations of physical behaviors throughout the day.

Comparison between predicted and measured resting energy expenditures in Korean male collegiate soccer players

This study aimed to evaluate the differences between predicted resting energy expenditure (REE), using fat-free mass (FFM)-based prediction equations, and measured REE in Korean male collegiate soccer players. Fifteen male collegiate soccer players (18-21 years) participated in this study. The REE measurements were conducted using the Douglas bag method. Body composition was measured by dual-energy X-ray absorptiometry (DXA). The differences between the measured REE and predicted REE, using the five FFM-based REE equations, were analyzed using the t-test, calculation of errors, regression analysis, and the Bland-Altman method. The Cunningham (1980) and ten Haaf and Weijs (2014) equations showed significantly overestimated REE (1,808 ± 99 kcal/d, p <0.01; 1,838 ± 103 kcal/d, p <0.01; respectively), but the Owen (1988), Taguchi (2011), and Kim (2015) equations' estimations were not significantly different from the measured REE (1,589 ± 106 kcal/d, 1,640 ± 124 kcal/d, and 1,622 ± 68 kcal/d, respectively). The Taguchi equation gave the best prediction of REE with the lowest constant error (-6 ± 125) and effect size (-0.05), and a non-significant proportional bias (p = 0.95). The Taguchi equation is recommended for predicting REE in Korean collegiate soccer players. The selection process of a REE-prediction equation must take into consideration the target population's characteristics. Future studies are recommended to evaluate the validity of the different FFM-based REE-prediction equations in various Korean athletes.

Effects Of Increased Energy Availability On Energy Metabolism And Blood Indices In Healthy Young Men

Previous studies showed that low energy availability (low EA) condition affects resting energy expenditure (REE) and blood indices such as insulin-like growth factor-1 (IGF-1). Skipping breakfast may lead to low EA, as it reduces daily energy intake. In addition, skipping breakfast reduces protein intake, which may affect blood nutrition markers and muscle protein breakdown. PURPOSE: To examine the effects of increased EA on energy metabolism and blood indices in healthy young men. METHODS: Ten healthy young men who are habitually skipping breakfast participated in this study (age: 24 ± 4 years). Two conditions of EA-adjusted meals with low EA (LEA) and high EA (HEA) were provided one week each. In the LEA condition, the subjects skipped breakfast as usual and consumed meals of EA less than 30 kcal/kg FFM/day. Then, the subjects consumed three meals per day of EA more than 45 kcal/kg FFM/day in the HEA condition. All measurements were conducted after ingestion of each EA diet. REE was measured using the Douglas bag method (REEm), predicted REE (REEp) was calculated using the formula for Japanese people, and the ratio of REEm to REEp was calculated (REEratio). Early morning fasting blood indices were measured, and 3-methylhistidine (3-MH) as an indicator of muscle protein breakdown was measured using 24-hour urine storage. RESULTS: IGF-1 (LEA: 170.7 ± 43.0 ng/mL, HEA: 198.1 ± 43.2 ng/mL, p < 0.05) and transthyretin level (LEA: 23.4 ± 3.4 mg/dL, HEA: 27.1 ± 4.0 mg/dL, p < 0.05) were significantly higher in the HEA than the LEA condition. Retinol-binding protein level was below the reference value (2.7 - 6.0 mg/dL) in the LEA condition, however, significantly increased after the HEA condition (LEA: 2.5 ± 0.5 mg/dL, HEA: 2.9 ± 0.5 mg/dL, p < 0.01). REEratio (LEA: 0.92 ± 0.08, HEA: 0.99 ± 0.09) showed a tendency to improve after the HEA condition. CONCLUSIONS: This study indicated that adequate EA with three meals per day, even for a short period of time, might improve blood protein indices and IGF-1 level. Examination of adequate EA on energy metabolism and muscle protein breakdown requires long-term intervention.

Comparative study of a novel portable indirect calorimeter to a reference breath-by-breath instrument and its use in telemedicine settings.

Resting Energy Expenditure (REE) quantitatively describes the calories used to support body function (e.g. breathing, blood circulation, etc.) at resting condition. Assessment of the REE is essential for successful weight management and the understanding of metabolic health. REE is typically determined via indirect calorimetry. Current biomedical indirect calorimetry technologies, utilizing assessment of oxygen consumption (VO2) and carbon dioxide production (VCO2) rates (which are typically in the form factor of a metabolic cart) are bulky and require on-site calibration and/or trained professionals to operate. We introduce a novel wearable medical device with FDA clearance to determine REE accurately, portable, and user-friendly format, which can be used both by health professionals in a clinical environment and by the patient at home. Previously, we have reported the validation of Breezing Med (also named as Breezing Pro™) through Douglas Bag Method, a gold standard for gas exchange measurement, and excellent agreement has been found between the two methods for the determination of REE, VO2, and VCO2 rates (Mora etal., 2020). Now we present the validation of Breezing Med against Medical Graphics (MGC) CPX Ultima™, a FDA 510k cleared metabolic cart, which principle is based on breath-by-breath analysis. In addition, we present Breezing Med as a tool for daily measurement of metabolic rate by the lay person at home. A) The validation study was executed via parallel measurement of 20 healthy participants under resting conditions using both the Breezing Med and the MGC Ultima CPX™ (10min test). B) Breezing Med measurements were carried out by six subjects at home during stay-at-home order due to COVID-19 for 30 days. A) The resulting measurements from both devices was compared with correlation slope's and R-squared coefficients close to 1. B) Results were recorded and analyzed for variability. The pilot study demonstrated the advantage of Breezing Med device to be easy-to-use at home by lay people, which make the valuable device for telemedicine applications related to weight management from home. This result shows that the MGC Ultima CPX™ and Breezing Med are substantially equivalent for REE measurement; and an advantage of this device for metabolic assessment under the current COVID-19 pandemic situation, for people with impaired physical mobility, and for those who lives in rural areas or face impediments that limit physical access to care.

Within-Day Energy Balance and Metabolic Suppression in Male Collegiate Soccer Players.

Metabolic suppression due to relative energy deficiency can cause various physiological impairments in athletes. The purpose of this study was to evaluate within-day energy balance (WDEB) and the ratio between measured and predicted resting energy expenditure (REEratio) and to investigate the relationships between the markers of metabolic suppression. Ten male collegiate soccer players completed a 7-day food diary, physical activity, and heart rate records during the training and rest days. Energy intake (EI) and energy expenditure (EE) were analyzed to evaluate WDEB components. Body composition was measured using dual-energy X-ray absorptiometry (DXA), and blood sampling was conducted for hormonal analysis. The REE was measured using the Douglas bag method and predicted using the DXA-predicted method to calculate the REEratio. Participants were categorized into the normal (REEratio ≥ 0.94, n = 5) and suppressed (REEratio < 0.94, n = 5) groups. There were no group differences in the components of WDEB, except diet-induced thermogenesis (DIT), but EI was significantly higher in the normal group than in the suppressed group (7-day total: 3660 ± 347 vs. 3024 ± 491 kcal/day, p = 0.046 and rest days: 3772 ± 463 vs. 2796 ± 800 kcal/day, p = 0.046). Analysis of hormonal markers of metabolic suppression only showed a significant positive association between insulin-like growth factor-1 (IGF-1) and REEratio (r = 0.771, p = 0.009). The relationships between metabolic suppression and the markers of energy deficiency were inconclusive. There are possible associations of insufficient EI and IGF-1 levels with metabolic suppression, and further study is required to understand energy deficiency in male soccer players.

Abstract 14433: High Intensity Exercise Training Safely Increases Cardiorespiratory Fitness in Patients With Hypertrophic Cardiomyopathy

Introduction: Patients with hypertrophic cardiomyopathy (HCM) are excluded from high intensity activities due to perceived fear of sudden cardiac death. Observational data from athletes with HCM suggest that engaging in high intensity exercise (HIE) may be safe and is associated with higher cardiorespiratory fitness. Whether HIE can safely elicit a superior increase in fitness compared to moderate intensity exercise in patients with HCM is unclear. Methods: Nine HCM patients (49 ± 7 years, 3 female) were assessed for maximal oxygen uptake (VO 2 max, Douglas Bag method), cardiac output (Q c , acetylene rebreathing), and peripheral oxygen extraction (av-O 2 diff, Fick equation) before randomization and after 5 months of MIE or HIE training. Patients completed 3-4 sessions of MIE each week, while the HIE group also incorporated 1-2 supervised high intensity interval training sessions/week from month 3 onwards. Arrhythmias were monitored via pre-existing implantable cardiac defibrillators or implantable loop recorders placed prior to training. Results: Five months of MIE increased absolute VO 2 max by 3% and relative VO 2 max by 4%, while HIE consistently increased absolute VO 2 max by 6% and relative VO 2 max by 5% (Figure). Maximal Q c did not change after MIE but increased in all HIE patients (+1.2L/min, 95% CI -1.4 to 3.9), while maximal av-O 2 diff remained stable in both groups. Training compliance was 84 ± 15% in HIE and 93 ± 11% in MIE. There were no serious exercise-related adverse events in either group though two HIE subjects had arrhythmias at rest: 1) 14-beat run of wide complex tachycardia of uncertain mechanism given underlying conduction disease prior to a training session, and 2) 11 beats of non-sustained ventricular tachycardia prior to post exercise testing. Conclusions: Preliminary findings show that five months of HIE safely and consistently increased cardiorespiratory fitness in patients with HCM, though overall the improvements were comparable to MIE.

Association of Low Energy Availability and Suppressed Metabolic Status in Korean Male Collegiate Soccer Players: A Pilot Study.

Low energy availability (EA) can impair physiological function in athletes. The purpose of this study was to investigate EA status, metabolic status, and bone metabolism with biochemical analysis in Korean male soccer players. Twelve male athletes (18–20 years) completed the study. Body composition and bone mineral density were measured using dual energy X-ray absorptiometry (DXA), while VO2 max was determined by an incremental exercise test. Blood samples were taken for bone marker and hormone analyses. Resting energy expenditure (REE) was measured using the Douglas bag method and predicted using the DXA method. Food diaries and heart rates (HR) during training were recorded, and the Profile of Mood States 2 and Eating Attitude Test 26 were completed. Group differences between low EA (LEA <30 kcal/kg FFM/d, n = 5) and high EA (HEA ≥30 kcal/kg FFM/d, n = 7) were evaluated. The mean EA of the all participants was 31.9 ± 9.8 kcal/kg FFM/d with only two participants having an EA above 45 kcal/kg FFM/d. LEA showed suppressed REE (LEA: 26.0 ± 1.7 kcal/kg/d, HEA: 28.8 ± 1.4 kcal/kg/d, p = .011) with a lower REEratio (LEA: 0.91 ± 0.06, HEA: 1.01 ± 0.05, p = .008) as well as a lower insulin-like growth factor 1 (IGF-1) level (LEA: 248.6 ± 51.2 ng/mL, HEA: 318.9 ± 43.4 ng/mL, p = .028) compared to HEA. There were no group differences in bone markers or other hormone levels. Korean male athletes exhibited low EA status with suppressed metabolism, but there was limited evidence on the effect of EA on bone metabolism, endocrine system, and psychological parameters.

High Intensity Exercise Training In Patients With Hypertrophic Cardiomyopathy

Patients with hypertrophic cardiomyopathy (HCM) are excluded from high intensity activities due to perceived fear of sudden cardiac death though data from athletes with HCM suggest competitive sport may be safe for some. Low cardiorespiratory fitness in sedentary HCM patients may confer a greater lifetime cardiovascular event risk than exercise per se. While moderate intensity exercise training in patients with HCM modestly increases fitness, high intensity exercise may be superior. PURPOSE: To compare the efficacy of five months of moderate intensity exercise and high intensity exercise training to improve cardiorespiratory fitness (V̇O2max) in patients with HCM. METHODS: Eight patients with HCM (50 ± 7 years, 3 female) were assessed for maximal oxygen uptake (V̇O2max, Douglas Bag method), cardiac output (Q̇c, acetylene rebreathing), and peripheral oxygen extraction (av-O2 diff, Fick equation) before randomization and after 5 months of moderate or high intensity exercise training. Patients completed 3-4 sessions of moderate intensity exercise each week, while the high intensity group also incorporated a weekly interval training session. RESULTS: Five months of moderate intensity exercise increased absolute V̇O2max by 3% and relative V̇O2max by 4%, while high intensity exercise consistently increased absolute V̇O2max by 6% and relative V̇O2max by 5% (Figure). Maximal Q̇c did not change after moderate intensity exercise (+0.0L [95% CI -2.0 to 1.7]) but increased in all three patients after high intensity exercise (+1.2L [95% CI -1.4 to 3.9]), while maximal av-O2 diff remained stable in both groups (moderate intensity: +0.8mL/100mL [95% CI -1.0 to 2.6]; high intensity: -0.5mL/100mL [95% CI -3.6 to 2.7]). CONCLUSION: Preliminary findings show similar increases in cardiorespiratory fitness following five months of moderate and high intensity exercise training in patients with HCM, although improvements were more consistent after high intensity exercise.

The CO2 stimulus duration and steady-state time point used for data extraction alters the cerebrovascular reactivity outcome measure.

What is the central question of this study? Cerebrovascular reactivity (CVR) is a common functional test to assess brain health, and impaired CVR has been associated with all-cause cardiovascular mortality: does the duration of the CO2 stimulus and the time point used for data extraction alter the CVR outcome measure? What is the main finding and its importance? This study demonstrated CVR measures calculated from 1 and 2min CO2 stimulus durations were significantly higher than CVR calculated from a 4min CO2 stimulus. CVRs calculated from the first 2min of the CO2 stimulus were significantly higher than CVR values calculated from the final minute if the duration was ≥4min. This study highlights the need for consistent methodological approaches. Cerebrovascular reactivity to carbon dioxide (CVR) is a common functional test to assess brain vascular health, though conflicting age and fitness effects have been reported. Studies have used different CO2 stimulus durations to induce CVR and extracted data from different time points for analysis. Therefore, this study examined whether these differences alter CVR and explain conflicting findings. Eighteen healthy volunteers (24±5years) inhaled CO2 for four stimulus durations (1, 2, 4 and 5min) of 5% CO2 (in air) via the open-circuit Douglas bag method, in a randomized order. CVR data were derived from transcranial Doppler (TCD) measures of middle cerebral artery blood velocity (MCAv), with concurrent ventilatory sensitivity to the CO2 stimulus ( ). Repeated measures ANOVAs compared CVR and measures between stimulus durations and steady-state time points. An effect of stimulus duration was observed (P=0.002, η²=0.140), with 1min (P=0.010) and 2min (P<0.001) differing from 4min, and 2min differing from 5min (P=0.019) durations. sensitivity increased ∼3-fold from 1min to 4 and 5min durations (P<0.001, η²=0.485). CVRs calculated from different steady-state time points within each stimulus duration were different (P<0.001, η²=0.454), specifically for 4min (P=0.001) and 5min (P<0.001), but not 2min stimulus durations (P=0.273). These findings demonstrate that methodological differences alter the CVR measure.

Validation of a wearable metabolic tracker (Breezing ProTM) for Resting Energy Expenditure (REE) measurement via Douglas bag method

Background and aims: Resting Energy Expenditure (REE) is one of the most important metabolic parameters since it accounts for 60%-70% of total energy expenditure (TEE) in a typical population and 80%-90% in a sedentary one. Accurate measurement of REE is essential for weight control, nutrition management, and disease treatment. Though metabolic carts, desktop metabolic analyzers, and portable metabolic trackers are available on the market to address certain needs of metabolic rate measurement, a stand-alone and truly wearable metabolic tracker that can provide comfortable and natural breathing experience (e.g. lacking of nose clips and mouthpieces) for nasal and pulmonary disease-restricted users is preferred. Here is featured a novel, wearable,

Disadvantages of Automated Respiratory Gas Exchange Analyzers.

The use of automated gas exchange analysis systems in exercise studies is common throughout the industrialized world and are frequently used in sports medicine laboratories for the measurement of maximal oxygen uptake (VO2max), as an integrative parameter that allows the physical condition to be assessed, in spite of its limitations. Actually, the fundamental principles behind the measurement of respiratory gas exchange (RGE) have not changed for a century. It was used a manual Douglas bag method together with separate chemical analyses. The need for faster and more efficient techniques, has conditioned the traditional procedures and determined the emergence of automated systems. However, the validity and reliability of all these different systems is not well known. The common features associates with these systems, also have disadvantages that must be evaluated at the time of the acquisition of an automated equipment: (1) regular quality control checks, which entails other added economic costs, (2) the validity and reliability of the results, which it is necessary to verify, and (3) the user does not know the equations that determine the values of oxygen consumption and carbon dioxide production. This work aims to clarify the disadvantages of these automated systems. At maximum intensities, the variation of VO2max or VO2peak can be very significant in athletes and even more relevant in sick people undergoing a training program. Therefore, considerable care is needed when comparing RGE data with automated systems.New and NoteworthyActually, stress tests are more conveniently performed with automated systems. It is necessary to examine the validity and reliability of automated respiratory gas exchange systems. The algorithms incorporated in the software, apart from being a “mystery,” show differences with respect to the data provided.

Practical Considerations for Assessing Pulmonary Gas Exchange and Ventilation During Flume Swimming Using the MetaSwim Metabolic Cart.

Lomax, M, Mayger, B, Saynor, ZL, Vine, C, and Massey, HC. Practical considerations for assessing pulmonary gas exchange and ventilation during flume swimming using the MetaSwim metabolic cart. J Strength Cond Res 33(7): 1941-1953, 2019-The MetaSwim (MS) metabolic cart can assess pulmonary gas exchange and ventilation in aquatic environments. The aims of this study were: (a) to determine the agreement between minute ventilation (VE), pulmonary oxygen uptake (VO2), and carbon dioxide output (VCO2) using the MS and Douglas bag (DB) methods during flume swimming; and (b) to assess the repeatability of these and other MS-derived parameters. Sixteen trained swimmers completed a combined incremental and supramaximal verification cardiopulmonary swimming test to determine maximal VO2, 2 progressive intensity swimming tests during which MS and DB measurements were made (agreement protocol), and 3-4 constant-velocity submaximal swimming tests during which only the MS was used (repeatability protocol). Agreement was determined using limits of agreement (LoA), bias, random error, and 95% confidence intervals with systematic bias assessed using paired samples t-tests. Within-trial and between-trial repeatability were determined using the coefficient of variation (CV) and the repeatability coefficient (CR). Where data were heteroscedastic, LoA and CR were log-transformed, antilogged, and displayed as ratios. MetaSwim underestimated peak VO2 and VCO2 (≤0.39 L·min) and VE (9.08 L·min), whereas submaximal values varied between 2 and 5% for CV and ±1.09-1.22 for ratio CR. The test-retest CV during constant-velocity swimming for VE, tidal volume, breathing frequency, VO2, VCO2, and end-tidal pressures of O2 and CO2 was <9% (ratio CR of ±1.09-1.34). Thus, the MS and DB cannot be used interchangeably. Whether the MS is suitable for evaluating ventilatory and pulmonary responses in swimming will depend on the size of effect required.

Prediction of Physical Activity Intensity with Accelerometry in Young Children.

Background: An algorithm for the classification of ambulatory and non-ambulatory activities using the ratio of unfiltered to filtered synthetic acceleration measured with a triaxial accelerometer and predictive models for physical activity intensity (METs) in adults and in elementary school children has been developed. The purpose of the present study was to derive predictive equations for METs with a similar algorithm in young children. Methods: Thirty-seven healthy Japanese children (four- to six-years old) participated in this study. The five non-ambulatory activities including low-intensity activities, and five ambulatory activities were selected. The raw accelerations using a triaxial accelerometer and energy expenditure by indirect calorimetry using the Douglas bag method during each activity were collected. Results: For non-ambulatory activities, especially light-intensity non-ambulatory activities, linear regression equations with a predetermined intercept (0.9) or quadratic equations were a better fit than the linear regression. The equations were different from those for adults and elementary school children. On the other hand, the ratios of unfiltered to filtered synthetic acceleration in non-ambulatory activities were different from those in ambulatory activities, as in adults and elementary school children. Conclusions: Our calibration model for young children could accurately predict intensity of physical activity including low-intensity non-ambulatory activities.

Abstract 279: Cardiac Arrest is Associated With a Global Level Alteration in Oxygen Metabolism: A Clinical Pilot Study

Objective: We recently reported that a global-level metabolic alteration occurs after cardiac arrest (CA) in our high fidelity rodent model. The finding was that dissociation of O 2 consumption (VO 2 ) and carbon dioxide generation (VCO 2 ) resulted in a respiratory quotient (RQ: calculated by dividing VCO 2 by VO 2 ) that fell well outside the normally cited range of 0.7-1.0. We hypothesized that a lowered RQ is similarly found in human CA patients. Methods: The study consisted of three subject groups: 1) healthy volunteer, 2) post-surgical patient (control) and 3) post-CA patient. We measured the VO 2 and VCO 2 of mechanically ventilated subjects using the Douglas bag method. Inspiration and expiration gas samples were collected in two separate bags . and RQ was calculated from CO 2 and O 2 gas concentrations in the samples. The patients and healthy volunteers were ventilated using the same model mechanical ventilator. Alert healthy volunteers bit onto a mouthpiece and the samples were collected, while post-surgical and post-CA patients were unconscious during the measurements. We measured the RQ of healthy volunteers at normal and high fractions of inspired oxygen (FIO 2 ) in order to test the validity of our methods at various inspired O 2 levels. Results: The RQs of the three healthy volunteers were 0.83, 0.92 and 0.85 at an FIO 2 of 0.21 and 0.86, 0.88, and 0.83 at an FIO 2 of 0.90 respectively. The RQs of the two post-surgical patients were 0.92 and 0.88 at an FIO 2 of 0.5. None of the post-surgical patients had any complications following the surgery and all were discharged. The RQ of a post-CA patient measured 2.5 hours after the CA was found to be 0.72 at an FIO 2 of 0.9. The CA patient expired within 24 hours of hospital admission. Conclusions: The same trend between the findings of both our rodent study and the CA patient suggest that resuscitation from CA alters cellular metabolism on a global level. This metabolic alteration in turn causes the dissociation of O 2 consumption and CO 2 generation resulting in a lowered RQ. Our findings warrant a larger clinical study to confirm a lowered RQ in post-CA patients and bench work to elucidate the causative mechanism of this relationship.

Breathing resistance in automated metabolic systems is high in comparison with the Douglas Bag method and previous recommendations

The purpose of this study was to investigate the resistance to breathing in metabolic systems used for the distribution and measurement of pulmonary gas exchange. A mechanical lung simulator was used to standardize selected air flow rates ([Formula: see text], L/s). The delta pressure (Δ p, Pa) between the ambient air and the air inside the equipment was measured in the breathing valve’s mouthpiece adapter for four metabolic systems and four types of breathing valves. Resistance for the inspiratory and expiratory sides was calculated as RES = (Δ p/[Formula: see text]) Pa/L/s. The results for resistance showed significant ( p &lt; 0.05) between-group variance among the tested metabolic systems, breathing valves, and between most of the completed [Formula: see text]. The lowest resistance among the metabolic systems was found for a Douglas Bag system which had approximately half of the resistance compared to the automated metabolic systems. The automated systems were found to have higher resistance even at low [Formula: see text] in comparison with previous findings and recommendations. For the hardware components, the highest resistance was found for the breathing valves, while the lowest resistance was found for the hoses. The results showed that resistance in metabolic systems can be minimized through conscious choices of system design and hardware components.

Open-circuit respirometry: a brief historical review of the use of Douglas bags and chemical analyzers.

The Douglas bag technique is reviewed as one in a series of articles looking at historical insights into measurement of whole body metabolic rate. Consideration of all articles looking at Douglas bag technique and chemical gas analysis has here focused on the growing appreciation of errors in measuring expired volumes and gas composition, and subjective reactions to airflow resistance and dead space. Multiple small sources of error have been identified and appropriate remedies proposed over a century of use of the methodology. Changes in the bag lining have limited gas diffusion, laboratories conducting gas analyses have undergone validation, and WHO guidelines on airflow resistance have minimized reactive effects. One remaining difficulty is a contamination of expirate by dead space air, minimized by keeping the dead space <70 mL. Care must also be taken to ensure a steady state, and formal validation of the Douglas bag method still needs to be carried out. We may conclude that the Douglas bag method has helped to define key concepts in exercise physiology. Although now superceded in many applications, the errors in a meticulously completed measurement are sufficiently low to warrant retention of the Douglas bag as the gold standard when evaluating newer open-circuit methodology.

Comparison of daily physical activity parameters using objective methods between overweight and normal-weight children

PurposeThe purpose of the present study was to determine if there were any differences in various aspects of physical activity such as energy expenditure, intensity, and type of activity between normal-weight and overweight boys. MethodsChildren aged 9−12 years were recruited from 2 elementary schools located in different urban districts in Republic of Korea. The present study included 45 Korean boys, of which 19 were normal-weight and 26 were overweight. Daily physical activity was estimated over the same 1-week study period under free-living conditions using the doubly labeled water (DLW) method and a tri-axial accelerometer. Resting metabolic rate (RMR) was measured using the Douglas bag method and open-circuit indirect calorimetry. We calculated the physical activity level (PAL) as the total energy expenditure (TEE)/RMR. ResultsPAL was not significantly different between the groups. In the accelerometer data, time spent in locomotive moderate-to-vigorous physical activity (MVPA) was significantly lower in overweight boys than in normal-weight subjects, whereas other variables including non-locomotive activity did not differ between groups. In addition, among all participants, time spent in total locomotive activity was significantly associated with PAL. Time spent in locomotive MVPA was significantly associated with PAL. ConclusionOverweight boys may be less physically active based on locomotive MVPA, which was positively related with PAL. Our findings suggest that the contribution of locomotive MVPA to the increase in PAL was relatively significant.

Studies on the exercise physiology of draft horses performed in Japan during the 1950s and 1960s.

ABSTRACTAlthough the total number of horses raised in Japan dramatically decreased after World War II, because draft horses were still used for farm work in paddy fields and on farms during the period of the 1950s and 1960s, a performance test for selecting better draft horses was needed. In order to determine the most suitable size of draft horses for Japanese farm conditions, the working power of horses weighing from 185 to 622 kg was evaluated by performing an endurance test, several kinds of working power tests, and maximum pulling power tests. Oxygen consumption during draft exercise was measured by the Douglas bag method in order to evaluate effects of draft workload under the conditions of different types of work (14- and 18-cm plow depths, cultivator, and tillage), traction methods (shoulder traction, shoulder-trunk traction, and chest-trunk traction), walking speeds (40, 60, 80, 100, and 120 m/min), and depths of water (0, 18, 36, and 54 cm) on energy expenditure. The relationship between energy consumption and pulse rate during exercise was also evaluated. A study of a performance test for draft horses was conducted to establish a new approach for evaluating draft horse performance using heart rate as an index. For this study, a beat meter for measuring heart rate was developed, and experimental protocols were used to evaluate the relationship between heart rate and workload. Although the research results obtained from these studies do not have particular relevance in the current day, these studies are valuable for understanding the history of equine exercise physiology in Japan.

The Ventilation-Corrected ParvoMedics TrueOne 2400 Provides a Valid and Reliable Assessment of Resting Metabolic Rate (RMR) in Athletes Compared With the Douglas Bag Method.

The aim of the current study was to determine if a single ParvoMedics TrueOne 2400 metabolic cart provides valid and reliable measurement of RMR in comparison with the criterion Douglas Bag method (DB). Ten endurance-trained participants completed duplicate RMR measurements on 2 consecutive days using the ParvoMedics system in exercise mode, with the same expirate analyzed using DB. Typical error (TE) in mean RMR between the systems was 578.9 kJ or 7.5% (p = .01). In comparison with DB, the ParvoMedics system over-estimated RMR by 946.7 ± 818.6 kJ. The bias between systems resulted from ParvoMedics VE(STPD) values. A regression equation was developed to correct the bias, which reduced the difference to -83.3 ± 631.9 kJ. TE for the corrected ParvoMedics data were 446.8 kJ or 7.2% (p = .70). On Day 1, intraday reliability in mean RMR for DB was 286.8 kJ or 4.3%, (p = .54) and for ParvoMedicsuncorrected, 359.3 kJ or 4.4%, (p = .35), with closer agreement observed on Day 2. Interday reliability for DB was 455.3 kJ or 6.6% (p = .61) and for ParvoMedicsuncorrected, 390.2 kJ or 6.3% (p = .54). Similar intraday and interday TE was observed between ParvoMedicsuncorrected and ParvoMedicscorrected data. The ParvoMedics TrueOne 2400 provided valid and reliable RMR values compared with DB when the VE(STPD) error was corrected. This will enable widespread monitoring of RMR using the ParvoMedics system in a range of field-based settings when DB is not available.

Interval TRIMP Scores Predict Improvement in Maximal Oxygen Consumption in middle-aged, sedentary Individuals

PURPOSE: The optimal training strategy to maximize increases in VO2 max is unclear. We sought to compare the contribution of different training loads from an exercise program combining interval and continuous training on improvements in VO2 max. Training load was objectively quantified by the Training Impulse (TRIMP). METHODS: We studied 30 healthy sedentary participants (53.21±4.70 years, 14 males). Each participant was prescribed a progressive exercise prescription consisting of endurance and interval training. Between month 1 and 6, the exercise progressed to reach a peak phase, which was maintained for 3 months (weekly prescription: interval x2; one 60 min base pace; one 30 min base pace; one recovery). VO2max was measured at baseline and after completion of the peak phase of training via Douglas Bag method and incremental treadmill protocol. The training load for each continuous (TRIMPc = t · k1 · x { ) and interval exercise session (TRIMPi =) was calculated using the relevant equation. Total TRIMP scores (for all exercise), TRIMPc and TRIMPi scores were summed for the peak phase of training. Regression analysis was performed to determine correlation between these scores and percent change in VO2max. RESULTS: VO2max increased from 28.73±4.8 ml/kg/min at baseline to 34.43±5.6 ml/kg/min after training (P< 0.01). Total TRIMP score was 4411±1127 for the peak phase, while TRIMPc score was 2353±699 and TRIMPi score was 2059±638. Total TRIMP score did not correlate with increase in relative VO2max (R2 = 0.04, P=0.31), nor did TRIMPc score (R2=0.00 P=0.92). However, TRIMPi score correlated with increased VO2max (R2=0.14, P=0.05). Moreover, there was a significantly greater percent increase in relative VO2max in individuals whose TRIMPi scores were in the top third of the group compared to those in the bottom third (24.70%±9.10 vs15.11%±7.33, P=0.0188). CONCLUSIONS: Our data suggests that interval TRIMP scores predict changes in relative VO2max in middle-aged, sedentary individuals undergoing exercise training. In conclusion, interval training may provide a greater stimulus for aerobic adaptation than continuous endurance training.