Portable Metabolic System Research Articles

Home-based testing protocol to measure physiological responses to everyday activities in ME: a feasibility study

ABSTRACT Background and objectives Individuals with Myalgic Encephalomyelitis (ME) have shown altered physiological responses during maximum cardiopulmonary exercise testing. However, maximal testing is not representative of the everyday activities reported to cause or increase symptoms in ME, and is not accessible for those with severe or very severe illness. The aim of this study was to assess the feasibility and acceptability of a home-based testing protocol to measure physiological responses in ME to everyday activity. Methods Researchers attended participants’ homes to collect data and provide equipment for independent testing. Adults with ME who met the International Consensus Criteria wore a portable metabolic assessment system and a physiological stress monitor. Blood pressure, heart rate, oxygen saturation and lactic acid were assessed during a range of everyday positions and activities in their own homes. Results Online recruitment yielded 70 volunteers in 24 h. 17 eligible individuals reflecting a range of illness severities were enrolled. All participants found the procedures acceptable with 12 (70%) subjects completing every listed activity. Apparent physiological abnormalities were identified in all participants. Conclusion Physiological measurement during everyday activities was feasible for our participants who represented a range of ME severities. Activities must be adapted for different levels of severity to avoid significant symptom exacerbation. Further research is needed to develop home-based assessment protocols to advance the biobehavioral understanding of ME. Trial registration number: ISRCTN78379409.

Metabolic cost and mechanical work of walking in a virtual reality emulator.

The purpose of this study was to investigate the metabolic cost (C), mechanical work, and kinematics of walking on a multidirectional treadmill designed for locomotion in virtual reality. Ten participants (5 females, body mass 67.2 ± 8.1kg, height 1.71 ± 0.07m, age 23.6 ± 1.9years, mean ± SD) walked on a Virtuix Omni multidirectional treadmill at four imposed stride frequencies: 0.70, 0.85, 1.00, and 1.15Hz. A portable metabolic system measured oxygen uptake, enabling calculation of C and the metabolic equivalent of task (MET). Gait kinematics and external, internal, and total mechanical work (WTOT) were calculated by an optoelectronic system. Efficiency was calculated either as WTOT/C or by summing WTOT to the work against sliding frictions. Results were compared with normal walking, running, and skipping. C was higher for walking on the multidirectional treadmill than for normal walking, running, and skipping, and decreased with speed (best-fit equation: C = 20.2-27.5·speed + 15.8·speed2); the average MET was 4.6 ± 1.4. Mechanical work was higher at lower speeds, but similar to that of normal walking at higher speeds, with lower pendular energy recovery and efficiency; differences in efficiency were explained by the additional work against sliding frictions. At paired speeds, participants showed a more forward-leaned trunk and higher ankle dorsiflexion, stride frequency, and duty factor than normal walking. Walking on a multidirectional treadmill requires a higher metabolic cost and different mechanical work and kinematics than normal walking. This raises questions on its use for gait rehabilitation but highlights its potential for high-intensity exercise and physical activity promotion.

Experience with a medium chain triglyceride complex and changes in mental focus and score in different modes of golf transport and play

Medium Chain Triglyceride (MCT)- based supplements have increased cognitive function in general and specific functional realms. Can an MCT complex improve mental focus in sports with a high, active cognitive component? This pilot investigation tested whether the proprietary MCT complex utilized could result in positive gains in mental focus or perception of enhanced energy on the course. Each of the ten subjects played a 9-hole round using a motor cart, pushcart, carry bag, or electric trolley (which simulated playing with a caddie) while wearing a portable metabolic system to determine baseline energy expenditure, mental focus, and score baseline. Data points recorded and averaged included the volume of oxygen used per minute total (VO2/L/min), oxygen used per kg of body weight per minute (VO2ml/kg/min), converted to kcal per hour, and heart rate. A 10-point mental focus scale had golfers rating tee shots, second through fourth shots, and the short game from 100 yards in. Using their preferred mode of transport and play, the subjects completed one more, 9-hole round after once-daily consumption of the supplement for seven days. The average rating of mental focus and perceived energy increased from a level of 5.77 to 7.22 out of 10, statistically significant at P= 0.0120. Actual play scores decreased from 10.8 to 8.9 over par for the 9-hole rounds, trending positively. This initial trial suggests that a proprietary MCT complex can improve actual golf performance and the golfer's perceptions of focus and energy regardless of which mode of transport and play is used.

Comparative study of young-old and old-old people using functional evaluation, gait characteristics, and cardiopulmonary metabolic energy consumption

BackgroundWalking is an important factor in daily life. Among older adults, gait function declines with age. In contrast to the many studies revealing gait differences between young adults and older adults, few studies have further divided older adults into groups. The purpose of this study was to subdivide an older adult population by age to identify age-related differences in functional evaluation, gait characteristics and cardiopulmonary metabolic energy consumption while walking.MethodsThis was a cross-sectional study of 62 old adult participants who were classified into two age groups of 31 participants each as follows: young-old (65–74 years) and old-old (75–84 years) group. Physical functions, activities of daily living, mood state, cognitive function, quality of life, and fall efficacy were evaluated using the Short Physical Performance Battery (SPPB), Four-square Step Test (FSST), Timed Up and Go Test (TUG), Korean Version of the Modified Barthel Index, Geriatric Depression Scale (GDS), Korean Mini-mental State Examination, EuroQol-5 Dimensions (EQ-5D) questionnaire, and the Korean version of the Fall Efficacy Scale. A three-dimensional motion capture system (Kestrel Digital RealTime System®; Motion Analysis Corporation, Santa Rosa, CA, USA) and two force plates (TF-4060-B; Tec Gihan, Kyoto, Japan) were used to investigate spatiotemporal gait parameters (velocity, cadence, stride length, stride width, step length, single support, stance phase, and swing phase), kinematic variables (hip, knee, and ankle joint angles), and kinetic variables (hip, knee, and ankle joint moment and power) of gait. A portable cardiopulmonary metabolic system (K5; Cosmed, Rome, Italy) was used to measure cardiopulmonary energy consumption.ResultsThe old-old group showed significantly lower SPPB, FSST, TUG, GDS-SF, and EQ-5D scores (p < 0.05). Among spatiotemporal gait parameters, velocity, stride length, and step length were significantly lower in the old-old group than in the young-old group (p < 0.05). Among the kinematic variables, the knee joint flexion angles during initial contact and terminal swing phase were significantly higher in the old-old than the young-old group (P < 0.05). The old-old group also showed a significantly lower ankle joint plantarflexion angle during the pre- and initial swing phases (P < 0.05). Among the kinetic variables, the hip joint flexion moment and knee joint absorption power in the pre-swing phase were significantly lower in the old-old than the young-old group (P < 0.05).ConclusionThis study demonstrated that participants 75–84 years of age had less functional gaits than their young-old counterparts (65–74 years old). As the walking pace of old-old people diminishes, driving strength to move ahead and pressure on the knee joint also tend to decrease together with stride length. These differences in gait characteristics according to age among older adults could improve our understanding of how aging causes variations in gait that increase the risk of falls. Older adults of different ages may require customized intervention plans, such as gait training methods, to prevent age-related falls.Trial registrationClinical trials registration information: ClinicalTrials.gov Identifier: NCT04723927 (26/01/2021).

Metabolic demands of slacklining in less and more advanced slackliners

ABSTRACT Walking or balancing on a slackline has gained increasing popularity as a recreational and school sport, and has been found to be suitable for developing neuromuscular control. The metabolic requirements for neuromuscular control on slackline, however, have not been well described. Therefore, the aim of the study was to determine the metabolic demands of slacklining in less and more advanced slackliners. Nineteen slackliners performed several 4 min balance tasks: parallel and one-leg stance on stable platform (2LS and 1LS), 1 leg stance on a slackline (1LSS), walking at a self-selected speed and at a given speed of 15 m min−1 on a slackline (WSS and WGS). Expired gas samples were collected for all participants and activities using a portable metabolic system. During1 LS and 1LSS, there were 140% and 341% increases in oxygen uptake (V̇O2) with respect to V̇O2 rest, respectively. During slackline walking, V̇O2 increased by 460% and 444% at self-selected and given speed, respectively. More advanced slackliners required mean metabolic demands 0.377 ± 0.065 and 0.289 ± 0.050 kJ·kg−1·min−1 (5.7 ± 0.95 and 3.9 ± 0.6 MET) for WGS and 1LSS, respectively, whilst less advanced slackliners, 0.471 ± 0.081 and 0.367 ± 0.086 kJ·kg−1·min−1 (6.4 ± 1.2 and 5.0 ± 1.1 MET) for WGS and 1LSS, respectively. Our data suggest that balancing tasks on slackline require V̇O2 corresponding to exercise intensities from light to moderate intensity. More advanced slackliners had a ∼25% reduced energy expenditure when compared with lower ability counterparts during simple balance tasks on the slackline. Highlights Balancing on a slackline is metabolically demanding and slackline training is suitable not only to develop neuromuscular control but also to meet cardiovascular fitness demands. Improved postural control demonstrated by skilled slackliners reduces by ∼25% metabolic cost of balancing tasks on a slackline when compared to less skilled counterparts. Falls during slacklining increase the metabolic demands of the activity. Three falls per minute during walking on a slackline increase the oxygen uptake by ∼50%.

Energy expenditure compared to mental focus &amp; score in three modes of golf transport/play

How does energy expenditure (EE) vary in golf based on the mode of transport and play? Does walking in some form enhance mental focus and decrease scores? Do all forms of golf play qualify as health-improvement activity? To determine potential golf participation benefits, a pre-study VO2 test was used to compare EE from the trials. The ten subjects (n=10), six males and four females, were all regular golfers at an accessible public golf course. Subjects played nine-hole rounds using a motor cart (MC), pushcart (PC), and electric trolley (ET)while wearing a portable metabolic system. Data points were recorded and averaged for O2/L/min and converted to kcal per hour, oxygen consumption in VO2 ml/kg/min, and heart rate (HR). Subjects kept score and completed a mental focus survey, which rated tee shots, second to fourth shots, and the short game from 100 yards in for each trial. The MC play had the least average expenditure of the three modes of transport and play (211 kcal/hr.), followed by the ET (236 kcal/hr.) and the PC (288 kcal/hr.), p = 0.001. The ET had the highest mental focus score (6.63/10), followed by the PC (5.67) and the MC (5.01), p = .015. The average score to par was one stroke better for the two walking modes versus the MC (10.3 vs. 11.5), p= 0.1906580. Walking while playing had better potential health effects while improving positive focus and scoring benefits compared to a motor cart. Golf in the walking modes is a moderate-intensity physical activity, while MC play is lower in health and fitness benefit.

Sagittal plane ankle kinetics are associated with dynamic hip range of motion and gait efficiency in women with hip osteoarthritis.

Loss of sagittal plane hip range of motion (ROM) is a commonly reported walking gait impairment in people with hip osteoarthritis (OA). The purpose of this study was to evaluate whether sagittal plane hip ROM reduction and the resulting altered sagittal plane ankle kinetics during gait influence the energy cost of walking in people with hip OA. We evaluated 24 women with unilateral hip OA (60 ± 9.1 years; 29.4 ± 6.1 kg/m2 ). Sagittal plane hip ROM and peak ankle dorsiflexion moment were assessed by instrumented gait analysis. We also used a portable metabolic system to measure the energy cost of walking. Pearson correlations and regression analyses were performed to test our hypotheses. We found that greater involved limb sagittal plane hip ROM was associated with a larger ankle peak dorsiflexion moment at push-off during gait (R = 0.50, p = 0.01). Greater involved limb peak ankle dorsiflexion moment at push-off was associated with a lower oxygen consumption during gait (R = -0.51, p = 0.01). Involved limb peak ankle dorsiflexion moment at push-off predicted 26% of the variance in O2 cost. Statement of Clinical Significance: Sagittal plane hip ROM was associated with peak ankle dorsiflexion moment at push-off during gait in women with hip OA. Moreover, peak ankle dorsiflexion moment at push-off was associated with the energy cost of walking. Therefore, modifying sagittal plane hip ROM and peak ankle dorsiflexion moment could be a possible rehabilitation strategy to improve gait efficiency in women with hip OA.

Physiological responses during a single rebirthing (Breath work) session

Objective: The present report aimed to look at the physiological responses during a typical single Rebirthing session. Material and Methods: Ten healthy young women participated in the study. Their mean age, weight, and height were 37±2.7 years, 54.1±6.4 kg, and 161.2±4.9 cm, respectively. The Rebirthing sessions took place at the Israeli Rebirthing Center in Tel-Aviv. The treatments were carried out by a qualified Rebirthing therapist that has experienced thousands of rebirthing sessions during the last 15 years. Sessions were performed in a dark, quiet room and executed in a one-to-one set-up with the same trained therapist. After around 40-50 minutes, the session approached its end. Metabolic, cardiovascular, pulmonary, and gas-exchange variables were measured breath-by-breath using a commercial portable metabolic system. All data were transmitted wirelessly to an adjacent room in the clinic and continuously monitored by the study's chief researcher. Results: The primary study findings demonstrated that a typical Rebirthing session involving long (45-50 minutes) voluntary hyperventilation generated VO2, RER, HR, and O2 pulse matching well with the physiological demands of the procedure (breath work). At the same time, the ventilatory-related responses exhibited, as expected, exaggerated outcomes, illustrated by the high session's peak and average values of the depth (tidal volume), breathing frequency, and minute ventilation. Gas-exchange attributes showed extremely shallow end-tidal CO2 levels, high end-tidal O2, high respiratory exchange ratio, and very high levels of O2 and CO2 ventilatory equivalents. No significant grievances regarding participants' physical and mental/emotional feelings were reported in the present study. Conclusions: The present study could not solve the apparent divergence between the observed (acute) physiological responses (mainly severe Hypocapnia) and the subjective participants' pleasant emotional state, and in many cases, spiritually uplifting, at the end of each treatment session.

Changes in acceleration load as measured by inertial measurement units manifest in the upper body after an extended running task

ABSTRACT The purpose of this study was to investigate the behaviour of physiological load measures as well as ground reaction forces (GRF) and acceleration load during a prolonged running task that simulated the running demands of an intermittent team sport. Nineteen males completed a maximal aerobic fitness test and an extended running protocol across two sessions. Participants wore a portable metabolic system, and four inertial measurement units (IMU), one on each foot, the lower back and upper back. GRF were measured via an instrumented treadmill. Change in metabolic, IMU and GRF variables across five blocks during the running protocol were assessed using a one-way repeated measures ANOVA. The running protocol elicited large increases in heart rate and oxygen consumption over time. No statistically significant changes in any peak impact accelerations were observed. Resultant acceleration area under the curve (AUC) increased at the lower and upper back locations but was unchanged at the foot. GRF active peak but not impact peak increased during the prolonged run. The results of this study indicate that the effect of an extended running task on IMU measures of external mechanical load is manifested in the upper body, and is effectively measured by AUC.

Impact of step length asymmetry on walking energetics in women with hip Osteoarthritis: A pilot study

A step length difference between the involved and uninvolved limbs in participants with hip osteoarthritis (OA) has been reported. The implications of step length asymmetry on other aspects of walking mechanics are as yet unknown. The objective of the current study was to evaluate the consequences of step length asymmetry on motion of the center of mass (COM) and energy cost of walking. We hypothesized that (i) increased step length asymmetry is associated with decreased mechanical energy exchange; (ii) decreased mechanical energy exchange is associated with increased O2 cost; (iii) increased step length asymmetry is associated with increased oxygen O2 cost during walking in women with hip OA. We evaluated 24 women with unilateral hip OA using motion analysis as participants walked on a treadmill at self-selected speeds. Kinematic data were collected to compute step length asymmetry and mechanical energy exchange through the motion of COM. We also used a portable metabolic system to measure the energy cost of walking simultaneously. We used Pearson correlations and linear regression to test our hypotheses. We found that more asymmetric step lengths were associated with lower mechanical energy exchange (R2 = 0.231, p = 0.017). More mechanical energy exchange was associated with lower O2 cost during gait (R2 = 0.284, p = 0.009). Mechanical energy exchange predicted 54.5% of the variance in O2 cost after adjusting for self-selected walking speed. Findings suggest that modifying step length asymmetry could enhance metabolic gait efficiency indirectly by improving mechanical energy exchange in participants with hip OA.

Respiratory ventilation and inhaled air pollution dose while riding with a conventional and an electric-assisted cycle along routes with different elevation profiles

BackgroundDifferences in physical effort between cycling for transportation on an electric-assisted cycle (EAC) and a conventional cycle (CC) were previously studied. The effect of cycle type on respiratory ventilation and inhaled air pollution dose remains unclear. ObjectiveThe first aim was to predict respiratory ventilation while cycling on a conventional and electric-assisted cycle taking into account personal and route characteristics. The second aim was to predict the dose of inhaled pollutants while cycling on a conventional and electric-assisted cycle using the same independent variables. MethodsNineteen participants performed a maximal exercise test (lab test) and four cycling trips (field test): flat with CC and EAC, and hilly with CC and EAC. During each trip, heart rate, respiratory ventilation, oxygen uptake, and carbon dioxide production were measured continuously with a portable metabolic system. Cycling time, speed and distance as well as GPS coordinates were also recorded continuously. The ATMO-Street air pollution model was used to estimate black carbon (BC), nitrogen dioxide (NO2), particulate matter (PM2.5 and PM10) inhaled doses post hoc. Factors impacting respiratory ventilation and the dose of inhaled pollutants were estimated through linear mixed modelling including laboratory and field measurements. ResultsMean respiratory ventilation was predicted based on sex (-7.78 L/min for women), cycle type (-17.61 L/min for EAC), height gain (+0.07 L/min) and speed (+1.30 L/min). Inhaled dose of pollutants both for BC dose/km and BC dose/min was primarily predicted by cycle type (-31.62% and -34.68% for EAC compared to CC, respectively). Results were similar for the other pollutants. ConclusionsCycle type, sex, speed and route topography contribute to the respiratory ventilation and the use of an EAC reduces the dose of inhaled pollutants by 33% compared to the CC. Future projects could develop an app that predicts the cleanest route in real-time based on physical effort and ambient air pollution to increase the health benefits of cycling.

Accelerometer Calibration: The Importance of Considering Functionality.

To compare the accuracy and precision of a hip-worn accelerometer to predict energy cost during structured activities across motor performance and disease conditions. 118 adults self-identifying as healthy (n = 44) and those with arthritis (n = 23), multiple sclerosis (n = 18), Parkinson's disease (n = 17), and stroke (n =18) underwent measures of motor performance and were categorized into groups: Group 1, usual; Group 2, moderate impairment; and Group 3, severe impairment. The participants completed structured activities while wearing an accelerometer and a portable metabolic measurement system. Accelerometer-predicted energy cost (metabolic equivalent of tasks [METs]) were compared with measured METs and evaluated across functional impairment and disease conditions. Statistical significance was assessed using linear mixed effect models and Bayesian information criteria to assess model fit. All activities' accelerometer counts per minute (CPM) were 29.5-72.6% less for those with disease compared with those who were healthy. The predicted MET bias was similar across disease, -0.49 (-0.71, -0.27) for arthritis, -0.38 (-0.53, -0.22) for healthy, -0.44 (-0.68, -0.20) for MS, -0.34 (-0.58, -0.09) for Parkinson's, and -0.30 (-0.54, -0.06) for stroke. For functional impairment, there was a graded reduction in CPM for all activities: Group 1, 1,215 CPM (1,129, 1,301); Group 2, 789 CPM (695, 884); and Group 3, 343 CPM (220, 466). The predicted MET bias revealed similar results across the Group 1, -0.37 METs (-0.52, -0.23); Group 2, -0.44 METs (-0.60, -0.28); and Group 3, -0.33 METs (-0.55, -0.13). The Bayesian information criteria showed a better model fit for functional impairment compared with disease condition. Using functionality to improve accelerometer calibration could decrease variability and warrants further exploration to improve accelerometer prediction of physical activity.

Application of the Modified Incremental Step Test for Pulmonary Rehabilitation.

A Modified Incremental Step Test (MIST) performed in the home may facilitate entirely home-based pulmonary rehabilitation programs. The aims of this study were to investigate the reliability and responsiveness, and the utility of the MIST for exercise prescription in people with stable chronic lung disease. The MIST was undertaken at the center and home in random order, before and after pulmonary rehabilitation, with 2 tests at each time point. Reliability was assessed using intraclass correlation coefficient. Responsiveness was evaluated as effect size. The minimal important difference was appraised using distribution and anchor-based methods. In a substudy, physiological responses to MIST were measured by a portable metabolic system, followed by a constant step rate test at 60% of peak oxygen uptake (VO2peak), to evaluate utility for exercise prescription. Forty-six participants were recruited (29% of eligible candidates). There was excellent reliability for number of steps recorded in home- and center-based settings (intraclass correlation coefficient = 0.954, 95% CI = 0.915-0.976). A small-moderate effect size was demonstrated following pulmonary rehabilitation (0.34), and the minimal detectable change was 7 steps. All participants in the substudy achieved 60% of VO2peak and achieved steady state by the fourth minute, with 60% of VO2peak corresponding to a mean 37% (95% CI = 29-44) of the MIST final level. The MIST is reliable and responsive to pulmonary rehabilitation in people with stable chronic respiratory disease. It provides new opportunities to assess exercise capacity, prescribe exercise training, and reassess exercise program outcomes in environments where established field walking tests are not feasible. Pulmonary rehabilitation is a highly effective treatment that is underutilized worldwide. Home-based pulmonary rehabilitation may improve access for patients and deliver equivalent clinical outcomes but is limited by the availability of a robust exercise test that can be used at home to assess exercise capacity and prescribe training intensity. This study tested the clinimetric properties of the MIST and demonstrated a new way to assess exercise capacity, prescribe exercise training of an appropriate intensity, and reassess exercise capacity in environments where established field walking tests are not feasible.

Reexamining the Energy Cost of Sedentary Behaviors From the 2011 Adult Compendium.

This study reexamines the energy cost of lower intensity activities compared to the 2011 Adult Compendium of Physical Activities. Participants (n = 32, age = 35 [13.8]y, 16 females) wore a portable metabolic system (COSMED), during 5 different conditions: sitting quietly, watching TV, sitting while working, driving, and walking at 2.0mph. The metabolic equivalent (MET) values (VO2 mL·kg-1·min-1/3.5mL·kg-1·min-1) were calculated. The mean (SD) MET value for driving (1.46 [0.24]) was significantly lower than the Adult Compendium value of 2.5 (P < .001). Driving and slow walking have similar Adult Compendium values, but driving METs were significantly lower than slow walking (P < .001). Driving was similar to sitting while working (1.32 [0.25]METs, P > .05) and yielded significantly higher MET values than quiet sitting (1.08 [0.23]METs, P < .001) and watching TV (1.12 [0.22]METs, P < .001), both of which were lower than their respective Adult Compendium MET values. Existing Adult Compendium METs are significantly higher than measured METs for driving, which more closely correspond to sedentary behaviors than slow walking. The TV and quiet sitting also differed from their Adult Compendium values, which should be updated to reflect these findings, given that researchers and practitioners rely on Adult Compendium MET values to estimate energy cost.

Respiratory, cardiac and metabolic responses during electrical muscle stimulation in quadriceps muscle versus comparable voluntary muscle contractions

Electrical Muscle Stimulation (EMS) and voluntary muscle contraction (VMC) are both acceptable rehabilitative modalities to preserve muscle strength loss. The study aimed to compare respiratory, metabolic, and cardiac parameters during quadriceps muscle contraction (QMC) using either EMS or VMC with comparable generated low intensity muscle force. Thirty healthy non-smoker males, age 20–58 years with normal BMI and low to moderate physical activity, underwent two 20-min sessions of comparable QMC using EMS vs VMC at the same day. The BIODEX III isokinetic dynamometer was used to assess maximum isometric force and the comparable force generated during each condition (EMS vs VMC), while the METAMAX 3B portable metabolic system was used to measure continuously the physiological parameters. Tolerable EMS was used (mean: 33 ± 1.5 mA, at 75 Hz). Each contraction lasted 10 sec followed by 20 sec rest. Paired t-tests were used for comparisons between sessions. A relatively low proportion of maximum isometric force (EMS: 8.5% vs VMC: 8.6%) and torque (EMS: 16 ± 1.3 vs VMC: 16 ± 1.1 Nm) were generated during each session. Mean minute ventilation (EMS: 10.8 L vs VMC: 9.8 L), tidal volume (EMS: 0.6 L vs VMC: 0.5 L), O2 uptake (EMS: 0.31 L/min vs VMC: 0.26 L/min) and O2 pulse (EMS: 3.9 ml/beat vs VMC: 3.6 ml/beat) were different between sessions (p ≤ .05); while heart rate (EMS: 72 beats/min vs VMC: 71 beats/min) was equal. Quadriceps muscle EMS induces higher respiratory and metabolic responses compared to equal magnitude VMC in healthy males.

Underlying mechanisms of oxygen uptake kinetics in chronic post-stroke individuals: A correlational, cross-sectional pilot study.

Post-stroke individuals presented deleterious changes in skeletal muscle and in the cardiovascular system, which are related to reduced oxygen uptake ([Formula: see text]) and take longer to produce energy from oxygen-dependent sources at the onset of exercise (mean response time, MTRON) and during post-exercise recovery (MRTOFF). However, to the best of our knowledge, no previous study has investigated the potential mechanisms related to [Formula: see text] kinetics response (MRTON and MRTOFF) in post-stroke populations. The main objective of this study was to determine whether the MTRON and MRTOFF are related to: 1) body composition; 2) arterial compliance; 3) endothelial function; and 4) hematological and inflammatory profiles in chronic post-stroke individuals. Data on oxygen uptake ([Formula: see text]) were collected using a portable metabolic system (Oxycon Mobile®) during the six-minute walk test (6MWT). The time to achieve 63% of [Formula: see text] during a steady state (MTRON) and recovery (MRTOFF) were analyzed by the monoexponential model and corrected by a work rate (wMRTON and wMRTOFF) during 6MWT. Correlation analyses were made using Spearman's rank correlation coefficient (rs) and the bias-corrected and accelerated bootstrap method was used to estimate the 95% confidence intervals. Twenty-four post-stroke participants who were physically inactive took part in the study. The wMRTOFF was correlated with the following: skeletal muscle mass (rs = -0.46), skeletal muscle mass index (rs = -0.45), augmentation index (rs = 0.44), augmentation index normalized to a heart rate of 75 bpm (rs = 0.64), reflection magnitude (rs = 0.43), erythrocyte (rs = -0.61), hemoglobin (rs = -0.54), hematocrit (rs = -0.52) and high-sensitivity C-reactive protein (rs = 0.58), all p < 0.05. A greater amount of oxygen uptake during post-walking recovery is partially related to lower skeletal muscle mass, greater arterial stiffness, reduced number of erythrocytes and higher systemic inflammation in post-stroke individuals.

Push-Rate Threshold for Physical Activity Intensity in Persons Who Use Manual Wheelchairs.

There is evidence that manual wheelchair users are among the least physically active in society. However, the current cut points for quantifying physical activity intensity based on steps per minute have been developed for ambulatory adults from the general population and other clinical populations and may not be appropriate or applicable for manual wheelchair users. This study examined the association between push rate (an analog of step rate) and energy expenditure across three speeds of treadmill wheelchair propulsion among manual wheelchair users and further generated a push-rate cut point for quantifying moderate-to-vigorous physical activity. Persons who used manual wheelchairs (N = 17) performed three, 6-min bouts of manual wheelchair propulsion on a motor-driven treadmill at speeds of 0.7, 1.3, and 2.0 m/sec. Push rate per trial was measured using SMARTwheels, and the rate of oxygen consumption per trial was measured using a portable metabolic system. The mean (SD) R2 value for the relationship between push rate and energy expenditure was 0.78 (0.14). The mean (SD) push-rate cut point for quantifying moderate-to-vigorous physical activity was 55.05 (26.06) pushes/min. This preliminary study provides the first push-rate cut point for quantifying moderate-to-vigorous physical activity among a heterogeneous sample of manual wheelchair users. This threshold may be important for public health promotion and individual-level monitoring and prescription of free-living physical activity behavior among manual wheelchair users.

Basal Energy Expenditure of Chinese Healthy Adults: Comparison of Measured and Predicted Values

ObjectiveThis study aimed to measure the basal energy expenditure (BEE) of Chinese healthy adults and establish an accurate predictive equation for this population. MethodsIn total, 470 Chinese healthy adults had their BEE measured using the Cosmed K4b2 portable metabolic system. Multiple linear regression analysis was applied to develop new optimal equations for predicting BEE. The bias, accuracy rate, concordance correlation coefficient (CCC), and root mean square error (RMSE) were used to evaluate the accuracy of the predictive equations. ResultsThere was a significant difference in BEE between males and females, with 5,954 kJ/d and 5,089 kJ/d, respectively. People living in rural areas expended significantly higher BEE (5,885 kJ/d) than those in urban areas (5,279 kJ/d). Previous equations developed by Henry, Schofield, Harris-Benedict (H-B), and Liu overestimated the BEE of Chinese healthy adults. The new equations derived from the present study displayed the smallest average bias and RMSE from the measured basal energy expenditure (mBEE). The CCC of the new equations was higher than other predictive equations, but it was lower than 0.8. There was no significant difference in the accuracy rate among all predictive equations. ConclusionsSex and regional differences in BEE were observed in Chinese healthy adults. Neither the widely used previous predictive equations nor the one derived in the present study were accurate enough for estimating the BEE of Chinese healthy adults. Further study is required to develop more accurate equations for predicting the BEE of Chinese healthy adults aged between 20–45 years.

Overground Locomotor Training In Parkinson's Disease: Effects On Walking Economy And Performance Fatigability

Walking economy (WE) is a measure of metabolic energy expenditure relative to walking speed, and, when elevated, may contribute to decreased capacity and performance relative to sustained walking in people with Parkinson’s Disease (PD). Coupled with performance fatigability (PF), these factors may increase disability in this population. Although sustained walking underlies many daily activities and impacts physical activity for many people with PD, responses to walking-specific interventions to develop optimal training methods have not been fully investigated in this population. PURPOSE: Determine changes in WE, PF, and physiologic response during sustained walking following a task-specific, performance-based overground locomotor training program (OLT) in people with mild/moderate PD. METHODS: 7 males and 2 females (68.9 ± 7.1 years old, H&Y scores 1-3) completed a 12-week program of 24 OLT sessions lasting 45 - 60 minutes each. Subjects were coached through multiplanar movement drills based on components of the gait cycle emphasizing power, stability and stepping under aerobically challenging conditions (ClinicalTrials.gov. - NCT03864393). Walking performance was measured during an overground 10-minute walk test (10MWT) by total distance (TD) and PF (Δ speed/total distance). During the final 5 minutes of the 10MWT, average heart rate (HR), oxygen consumption (V̇O2), and carbon dioxide production (V̇CO2) were recorded using a portable metabolic system. These values were divided by the average speed in the final 5 minutes of the 10MWT to assess WE and physiologic response. RESULTS: There were moderate to large, significant effects for TD (925.77 ± 175.67 vs 1018.37 ± 133.83, p=0.019, d=0.59), PFS (1.11 ± 0.19 vs 0.98 ± 0.13, p=0.013, d=0.79) and HR/speed (76.46 ± 7.69 vs 71.49 ± 6.71 bpm/m/s, p=0.05, d=0.69). There were small, non-significant effects for V̇O2/speed (12.14 ± 1.99 vs 11.47 ± 2.89 mL/min/kg/m/s, d=0.34) and V̇CO2/speed (790.56 ± 196.8 vs 778.93 ± 197.94 mL/min/m/s, d=0.06). CONCLUSIONS: OLT improved WE and PFS during sustained walking. Despite a moderate effect, HR changes in response to OLT are difficult to interpret without additional measures of cardiorespiratory function. Larger and more mechanistic studies can provide further insight into this potential adaptation.

Metabolic And Motor Proficiency Profiles Of Youth With Down Syndrome

Two factors that have a significant impact on obesity levels are low resting metabolic rate (RMR) and insufficient physical activity (PA) levels. Impaired RMR and neuromuscular coordination are common in youth with Down syndrome (DS) and may contribute to high rates of obesity. PURPOSE: To determine the metabolic and motor proficiency profiles of a sample of youth with DS. METHODS: Participants were youth with DS (n=11; 7 females; 16.8±3.9 y) attending a weeklong therapeutic recreation camp. Height and weight were measured, body mass index (BMI) was calculated, and BMI percentiles were used to determine weight status. The participants’ RMR was evaluated in a supine position in a quiet, dark room for 15 minutes, using a portable metabolic system (Oxycon Mobile, Vyaire). One-minute averages were collected, and the first five minutes were excluded from the analysis. A rolling average technique was used to determine the average for each 5-min interval. The lowest rolling average was considered the RMR. The Bruininks-Oseretsky Test of Motor Proficiency Ed. 2 (BOT-2) Short Form was used to test motor proficiency. The BOT standard scores (range from 20 - 80) and age- and sex-specific percentiles were calculated for each participant using conversion tables in the BOT-2 administration manual. Spearman correlations were run to determine associations among BMI, RMR, and BOT-2 scores. RESULTS: The average BMI of the participants was 29.7±7.6 kg·m-2 (91% obese). Average RMR was 4.1±1.8 ml/kg/min. The average standard BOT-2 score was 26.8±3.8, average percentile was 1.4+0.7. All youth were classified as Well-Below Average. There were no significant correlations among the variables (p>0.05). CONCLUSIONS: RMR does not appear to be impaired in this sample. However, in this sample, the extremely low motor proficiency scores may contribute to limited PA participation and obesity levels. PA programs and interventions should consider addressing strategies to improve motor proficiency in youth with DS.