Cosmed K4b2 Research Articles

Post-exercise energy expenditure of half squat and bench press at different load percentages and controlled cadence

The aim of this study was to analyze the effect of movement velocity and intensity on EPOC fast component in bench press and half squat exercises performed to concentric failure. Twelve healthy recreational bodybuilders performed 10 days of experimental procedures: the 1st and 2nd days were to load determination (1RM test and re-test), the 3rd to 10th days performing the bench press and half squat exercises with 60 and 80% 1RM performed in slow (1s/1s) and high (2s/2s) movement velocity cadence 52 beats. Oxygen consumptionas continuously measured in the first 20-min post-exercise using Cosmed K4 b2 portable device. A multivariate analysis compared the EPOC averaged in each minute post-exercise according to the different exercises, intensities and movement velocities. Was observed that EPOC declines fast from the 1st to 2nd minute and attains almost 100% of the decline near resting VO2 values at the 3rd minute of recovery both exercises. Greatest EPOC accumulated, during the eight minutes, was to exercise that involved the largest muscle group (half squat) with high intensity (80% 1RM) and greater movement velocity (1s/1s). In the full 20-min interval, the half squat had an energy equivalent of almost 80% more compared with the bench press. The higher velocities enhance energy expenditure to a greater extent than a more fatiguing slower exercise.

Prediction of Cardiorespiratory Fitness Level of Young Healthy Women Using Non-Exercise Variables

Cardiorespiratory fitness (CRF) is considered an important indicator of health in children and adults. The main contribution of this paper is an analysis of cardiorespiratory fitness predictive models among a population of healthy and young women, using the non-exercise variables. The study was conducted on a group of 154 healthy women (aged 20.3 ± 1.2) from selected academic centers in Poland. The VO2max was measured using a Cosmed K4b2 portable analyzer during a 20 m shuttle test. In addition, selected anthropomotor parameters including body composition components were measured for each subject. The participants’ leisure-time physical activity was assessed using the Minnesota Leisure-Time Physical Activity Questionnaire. The Ridge regression was the most accurate model for estimating VO2max from anthropometric parameters. The most accurate model based on the level of leisure-time physical activity was calculated using stepwise regression for which the prediction error was at the level of 6.68 (mL·kg−1·min−1). The best model calculated from all non-exercise variables (age, anthropometric parameters, and leisure-time physical activity) had only two predictors: waist circumference and total physical activity, and had a prediction error equal to 6.20 (mL·kg−1·min−1).

Data repeatability for the Cosmed K4 b2 portable metabolic cart during non-steady state exercise

BACKGROUND: Portable metabolic carts are a popular tool to assess aerobic capacity and affirm many cardiorespiratory conditions. They may also measure strength training performance. Given their popularity and increased usage to assess strength training performance; their data accuracy and consistency are important to determine. OBJECTIVE: Measure Cosmed K4 b2 portable metabolic cart data repeatability from consecutive seated calf press workouts. METHODS: Fifteen women and twelve men did two workouts that began with a stationary cycling warm-up followed by calf presses. Gases were measured before the calf press portion of workouts to establish baseline VO2 and VCO2 values, as well as continually throughout and after the calf press protocol. Subjects were detached from the cart once gas values returned to baseline after workouts concluded. In addition to VO2 and VCO2, repeatability was quantified for: breaths per minute, tidal volume, ventilation, O2 uptake relative to body mass, expired O2 and CO2 fractions, percent fat and carbohydrate utilization, METS and total energy cost. Mean and peak values per variable were analyzed. Repeatability was assessed separately for male and female data, as well as with values pooled, by the following: intraclass correlation coefficients, eta squared, limits of agreement, coefficient of variation and smallest real difference percent. RESULTS: Per variable, repeatability values across workouts were low. Female intraclass correlation coefficient mean values were more repeatable for variables related to gas measurements, yet male data were generally more repeatable for those related to substrate usage. CONCLUSIONS: Results for some repeatability indices were influenced by measurement magnitude. Peak values were predictably less repeatable than those for mean values. Most smallest real differences percent scores are so high they were rendered irrelevant or meaningless to determine true differences among paired values. Results suggest low data repeatability that are likely appropriate and realistic for the exercise protocol, hardware and intensity examined.

Analysis of Resting Energy Consumption and Its Influencing Factors in Stroke Patients with Severe Neurological Diseases: A Retrospective Clinical Study

Background: This study aimed to observe the changes of resting energy metabolism in patients with severe neurological diseases, and to explore the effects of tracheostomy status, stroke severity, and complications on resting energy expenditure (REE) and respiratory quotient (RQ). Methods: A retrospective study was conducted in 105 patients with neurological rehabilitation who were hospitalized in the Rehabilitation Department of the Affiliated Jiangning Hospital of Nanjing Medical University from August 2018 to October 2021. REE was measured by Italian Cosmed k4b² indirectly, and white blood cell count and C-reactive protein (CRP) were collected. Results: Among the 105 patients, there were 18 cases of mild stroke, 45 cases of moderate stroke, and 42 cases of severe stroke. The difference between predicted REE and actual REE among different degrees of stroke patients was statistically significant (p < 0.05); there was no significant difference in RQ values among different degrees of stroke patients (p > 0.05). Hemoglobin, albumin, and body mass index were significantly and positively correlated with predicted REE and actual REE, while CRP was significantly negatively correlated with predicted REE and actual REE. There was no significant difference in predicted REE, actual REE, and RQ between renal insufficiency, type 2 diabetes mellitus, and chronic obstructive pulmonary disease (p > 0.05). The CRP level could affect the REE of stroke patients. Conclusion: Metabolic vehicle assay has a certain clinical value in accurately evaluating the metabolic needs and feeding level of patients.

Assessment of Energy Expenditure During Discrete Skill Performance Using Systematic Observation and Indirect Calorimetry

Purpose: To determine the accuracy of three systematic observation (SO) tools to estimate energy expenditure (EE) using different skill performance and observation intervals. Method: Three SO tools (Observational System for Recording Physical Activity in Children-Preschool, System for Observing Fitness Instruction Time, and System for Observing Play and Leisure Activity in Youth) were used to observe children (N = 42, Mage = 8.1 ± 0.7) during motor skill testing sessions. EE was measured using indirect calorimetry (COSMED K4b2). Results: Paired samples t tests, repeated-measures analysis of variance, and regression analyses were performed to compare the EE estimated from SO tools with EE measured by indirect calorimetry. The average mean difference between the estimated metabolic equivalence of task (METS) and actual METS ranged between −1.24 METS (SD = 1.62, p &lt; .01) and −3.46 METS (SD = 1.31, p &lt; .01) depending on skill performance interval or SO tool analyzed. Conclusions: SO tools did not accurately estimate EE during object control skill testing sessions. Physical educators should consider utilizing discrete motor skill practice to accumulate health-enhancing levels of physical activity while adhering to national standards.

Percentage Change in Reaction Time Can Predict Respiratory Quotient during Light Weight Schoolbag Carriage

While structured physical activity improves cardio-pulmonary parameters and Reaction Time (RT), heavy weight schoolbag carriage is detrimental. Schoolbag carriage may have either consequence. The purpose of this study is to explore the consequences of heavy and light weighing schoolbags on cardio-pulmonary parameters and RT. Healthy male participants (10-15 years) carrying schoolbags- 0%, 4%, 8%, 12%, 16% load of bodyweight walked (20-minutes) for 5 times each. For each of the 30 participants, during walks, COSMED k4b2 measured heart rate (HR), respiratory quotient (R), total energy expenditure (EEtot) and number of steps taken. Ruler-drop-test marked RT before and after each walk. RT improved after walking with schoolbags weighing 0%, 4% of bodyweight. RT didn’t improve for 8%, 12% carriage, worsened for 16% load carriage. HR and EEtot showed proportionality (r=0.24, p&lt;0.05), R correlated positively to percentage change in RT (r=0.24, p&lt;0.05) and inversely to number of steps taken (r=-0.40, p&lt;0.01). Percentage change in RT could significantly predict R (R=1.223+0.028(Percentage RT change)). Respiratory quotient can predict whether or not reaction time worsens for 20-minutes schoolbag carriage as per Receiver Operating Characteristic (ROC) curve (Area Under Curve (AUC)=0.668, 95% confidence interval: 0.558-0.779, p&lt;0.01). Carrying light-weight schoolbags (4% of bodyweight) for 20-minutes is beneficial, but heavy-backpack carriage effectuates adverse cardio-pulmonary response and higher RT.

Simultaneous Validation of Count-to-Activity Thresholds for Five Commonly Used Activity Monitors in Adolescent Research: A Step Toward Data Harmonization

Background: Multiple activity monitors are utilized for the estimation of moderate- to vigorous-intensity physical activity in youth. Due to differing methodological approaches, results are not comparable when developing thresholds for the determination of moderate- to vigorous-intensity physical activity. This study aimed to develop and validate count-to-activity thresholds for 1.5, 3, and 6 metabolic equivalents of task in five of the most commonly used activity monitors in adolescent research. Methods: Fifty-two participants (mean age = 16.1 [0.78] years) selected and performed activities of daily living while wearing a COSMED K4b2 and five activity monitors; ActiGraph GT1M, ActiGraph wGT3X-BT, activPAL3 micro, activPAL, and GENEActiv. Receiver-operating-characteristic analysis was used to examine the area under the curve and to define count-to-activity thresholds for the vertical axis (all monitors) and the sum of the vector magnitude (ActiGraph wGT3X-BT and activPAL3 micro) for 15 s (all monitors) and 60 s (ActiGraph monitors) epochs. Results: All developed count-to-activity thresholds demonstrated high levels of sensitivity and specificity. When cross-validated in an independent group (N = 20), high levels of sensitivity and specificity generally remained (≥73.1%, intensity and monitor dependent). Conclusions: This study provides researchers with the opportunity to analyze and cross-compare data from different studies that have not employed the same motion sensors.

Longitudinal changes in energy cost during walking in boys with Duchenne Muscular Dystrophy (DMD).

In boys with DMD, muscle weakness progresses in a proximal to distal pattern, leading to compensatory gait strategies, including hyperlordosis and equinus, that increase energy cost and accelerate the loss of walking capacity. The purpose of this study was to determine the changes in the energy cost of walking that occur with disease progression and to determine the optimal normalization scheme for the longitudinal assessment of the energy cost of walking in boys with DMD. Energy cost was assessed with the COSMED K4b2. Three normalization schemes were examined: gross energy cost (EC), net non-dimensional oxygen cost (NNcost) and speed-matched control energy cost (SMC-EC). Nonlinear mixed modeling procedures determined the rate of change with age. Linear regression was used to asses the relationship between each normalization scheme and age and body height. 74 boys with DMD were assessed for the energy cost of walking. Velocity decreased at a significant rate (-.00245/month, p = .03) across time; (Fig. 2), while gross EC (.003248/month, p = 0.0026), NNcost (.006155/month, p < 0.0001) and SMC-EC (.001690/month, p = 0.03) all increased significantly. Age and height were significantly associated with NNcost and SMC-EC. The sensitivity of NNcost and SMC-EC to age over time were similar, while SMC-EC was less sensitive to changes in height over time than NNcost. In contrast to able-bodied peers, boys with DMD decrease their velocity while all walking energy cost measures increased over time. Both SMC-EC and NNcost proved appropriate normalization schemes for boys with DMD. Compared to gross EC, both NNcost and SMC-EC were less sensitive to changes in age over time, while SMC-EC was less sensitive to changes in height than NNcost. Therefore, both NNCost and SMC-EC are suggested normalization schemes for the longitudinal assessment of energy cost in boys with DMD.

Outdoor E-trike cycling: A low intensity physical activity

ABSTRACT For people with disabilities or chronic diseases, an electrically supported tricycle (e-trike) could facilitate independence and participation in physical activity, and improve health conditions. This study investigates the exercise intensity and perceived exertion of e-trike cycling. Twenty healthy participants cycled on an e-trike with different speeds (12 and 18 km/h) and different levels of electric pedal support at an outdoor athletics track. Exercise intensity was measured with oxygen consumption () using a Cosmed K4B2 analysis unit, perceived exertion was measured with the Borg Rating of Perceived Exertion scale, pedaling power, and engine power were measured with a torque sensor. The effect of speed and support was analyzed with a Linear Mixed Effects model. was 18.67 ± 3.13 ml/kg/min without support, with electric support the exercise intensity was significantly below moderate intensity (i.e. 10.5 ml/kg/min) at t = 11.37, p < .001, 95% CI: 1.90, 2.77. The Borg score without support was 9.79 ± 1.72 and all other conditions below this, which were significantly below moderate intensity (i.e. 11) at t = −3.07, p = .007, 95% CI: −2.04, −0.38. Speed and support significantly affected (F = 185.49, p < .001). E-trike cycling is a low intensity activity, but intensity can be influenced by changing speed and support level.

The Validity of an Updated Metabolic Power Algorithm Based upon di Prampero's Theoretical Model in Elite Soccer Players.

The aim of this study was to update the metabolic power (MP) algorithm (, W·kg−1) related to the kinematics data (PGPS, W·kg−1) in a soccer-specific performance model. For this aim, seventeen professional (Serie A) male soccer players ( 55.7 ± 3.4 mL·min−1·kg−1) performed a 6 min run at 10.29 km·h−1 to determine linear-running energy cost (Cr). On a separate day, thirteen also performed an 8 min soccer-specific intermittent exercise protocol. For both procedures, a portable Cosmed K4b2 gas-analyzer and GPS (10 Hz) was used to assess the energy cost above resting (C). From this aim, the MP was estimated through a newly derived C equation (PGPSn) and compared with both the commonly used (PGPSo) equation and direct measurement (). Both PGPSn and PGPSo correlated with (r = 0.66, p < 0.05). Estimates of fixed bias were negligible (PGPSn = −0.80 W·kg−1 and PGPSo = −1.59 W·kg−1), and the bounds of the 95% CIs show that they were not statistically significant from 0. Proportional bias estimates were negligible (absolute differences from one being 0.03 W·kg−1 for PGPSn and 0.01 W·kg−1 for PGPSo) and not statistically significant as both 95% CIs span 1. All variables were distributed around the line of unity and resulted in an under- or overestimation of PGPSn, while PGPSo routinely underestimated MP across ranges. Repeated-measures ANOVA showed differences over MP conditions (F1,38 = 16.929 and p < 0.001). Following Bonferroni post hoc test significant differences regarding the MP between PGPSo and /PGPSn (p < 0.001) were established, while no differences were found between and PGPSn (p = 0.853). The new approach showed it can help the coaches and the soccer trainers to better monitor external training load during the training seasons.

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.

Energy Cost Of Selected Household Physical Activities In Adults

According to the 2018 American Time Use Survey, nearly 78% of US adults spend from 2.0-2.5 hours/day in housework activities that include cleaning, laundry, straightening up, cooking, washing dishes and other activities. Another 11% of adults spend nearly 1.0 hour/day caring for older household adults. As many adults do household activities, there is interest in knowing the energy costs of such activities. PURPOSE: To update the MET values in the 2011 Adult Compendium of Physical Activities (Compendium) with measured oxygen uptake MET values for selected household physical activities (PAs) in adults. METHODS: The energy costs of six meal-related, five household cleaning, and two other care PAs were measured in 20 adults ages 20-59 (10 males, 10 females). Each simulated PA was performed in a laboratory setting for 8-min with a 4-min rest between PAs. Submaximal VO2 (ml/kg/min) and heart rate (beats/min) were measured with a Cosmed K4b2 portable indirect calorimetry system. METs were computed as VO2 in ml/kg/min divided by 3.5 ml/kg/min. Subjects self-rated their PA and physical fitness level as low, middle or high. RESULTS: Subject characteristics were averaged for age (33.7 + 11.2 yrs.), weight (67.9 + 12.0 kg), and height (166.1 + 7.4 cm). MET values were averaged up or down to reflect terminal digit values as presented in the 2011 Compendium (0, 3, 5, 8). MET values: carrying groceries on level surface (3.5), putting away groceries (2.5), food prep and cooking while standing (1.8), food prep and cooking while sitting (1.8), setting the table (2.3), clearing the table and washing dishes (2.0), folding and putting away laundry (2.0), putting away household items (3.0), major cleaning (3.0), sweeping sidewalk (3.0), watering plants (1.8), other care feeding/grooming (1.8), other care bathing/dressing (2.8). Heart rates ranged from 74 to 92 beats/min across all PAs. PA and fitness levels were rated as middle. CONCLUSIONS: Measured MET values were generally lower (on the order of 0.3 to 1.2 METs) than estimated MET values presented in the 2011 Compendium. Measured MET values were the same as the 2011 Compendium for putting away groceries and putting away household items. Overall, measured MET values for frequently performed household activities are rated as low- to moderate intensity. Supported by the Shanghai University of Sport

Energy Cost Of Selected Supine, Sitting, And Standing Sedentary Behaviors In Adults

Sedentary behaviors are persuasive in all societies. According to the 2018 American Time Use Survey, nearly 96% of adults spend 4-5 hours/day in sedentary behaviors that include watching TV, reading, computer use, relaxing and thinking. Since sedentary behaviors increase chronic disease risks, interest is high in knowing the energy costs of sedentary behaviors to help populations to reduce time spent in sedentary behaviors. PURPOSE: To update the energy costs of sedentary behaviors in the 2011 Adult Compendium of Physical Activities. METHODS: Energy cost in ml.kg-1.min-1 and heart rate in b.min-1 were measured by Cosmed K4b2 portable indirect calorimetry system in 10 males and 9 females (20-59y), mean age (31.6 ± 7.5 y), weight (63.4 ± 8.9 kg), and height (167.1 ± 5.8 cm). The subjects completed 17 randomly assigned behaviors in lying, reclining, sitting, and standing positions (doing nothing, watching TV, reading, writing, texting, typing, fidgeting) for 5 min with a 2 min rest between behaviors. Mean ± SD were computed with data presented as mean METs computed as VO2 ml.kg-1.min-1 / 3.5 ml.kg-1.min-1. Terminal digits for MET values were rounded to 0, 3, 5, or 8 to comply with format of the Compendium. RESULTS: Mean MET values are presented by behaviors and postures performed. Doing nothing (lie: 1.3, sit: 1.3. stand: 1.0); Watching TV (lie: 1.3, sit: 1.3); Reading (recline; 1.5, sit: 1.0); Writing (recline: 1.5, sit: 1.3, stand: 1.3); Texting (recline: 1.3, sit: 1.0, stand: 1.0); Fidgeting (sit hands only: 1.5, sit feet only: 1.8, stand hands & feet: 2.0); Typing (stand: 1.3). Of the measured MET values, seven were the same as the Compendium, four were lower (on the order of 0.3 to 0.8 METs), and one was higher by 0.3 METs (Recline: read). Heart rates during the behaviors ranged from 62 to 80 beats.min-1. CONCLUSIONS: The measured mean MET values ranged from 1.0 to 2.0 METs, classified as inactive (1.0-1.49 METs) and light activity (1.5-2.9 METs). Duplication of measured MET values to those in the Compendium confirm the energy cost of common sedentary behaviors. Of the four behaviors with lower measured MET values, three had been estimated in the Compendium (Sit: read, text; Stand text). Four behaviors not in the 2011 Compendium were measured (Recline: write, text; Stand: write, text). Supported by the Shanghai University of Sport

Estimation of Physical Activity Intensity in Spinal Cord Injury Using a Wrist-Worn ActiGraph Monitor

ObjectivesTo derive accelerometer count thresholds for classifying time spent in sedentary, light intensity, and moderate-to-vigorous physical activity (MVPA) in manual wheelchair users (MWUs) with spinal cord injury (SCI). DesignParticipants completed 18 activities of daily living and exercises for 10 minutes each with a 3-minute break between activities while wearing a COSMED K4b2 portable metabolic cart and an ActiGraph activity monitor on the dominant wrist. A linear regression was computed between the wrist acceleration vector magnitude and SCI metabolic equivalent of task (MET) for 80% of the participants to obtain thresholds for classifying different activity intensities, and the obtained thresholds were tested for accuracy on the remaining 20% of participants. This cross-validation process was iterated for 1000 times to evaluate the stability of the thresholds on data corresponding to different proportions of sedentary, light intensity, and MVPA. MET values of 1.5 or lower were classified as sedentary behavior, MET values between 1.5 and 3 were classified as light intensity, and MET values of 3 or higher were classified as MVPA. The final thresholds were then validated on an out-of-sample independent dataset. ParticipantsMWUs (N=17) with SCI in the out-of-sample validation data set. InterventionsNot applicable. SettingResearch lab, community Main Outcome MeasuresAccelerometer thresholds to classify sedentary, light intensity, and MVPA were obtained and their accuracy tested using cross-validation and an out-of-sample dataset. ResultsThe threshold between sedentary and light intensity was 2057 counts-per-minute, and the threshold between light intensity and MVPA was 11,551 counts per minute. Based on the out-of-sample validation, the obtained thresholds had an overall accuracy of 85.6%, with a sensitivity and specificity of 95.3% and 97.4% for sedentary behavior, 87.8% and 84.5% for light intensity, 68.5% and 96.3% for MVPA, respectively. ConclusionAccelerometer-based thresholds can be used to accurately identify sedentary behavior. However, thresholds may not provide accurate estimations of MVPA throughout the day when participants engage in more resistance-based activities.

Effect of Modified Bobath Cuff on Energy Expenditure and Fatigue during Level Surface Waking among Subjects with Hemiplegic Shoulder Subluxation: A Prospective Study

Background: This research study aims to find the effect of modified bobath cuff on energy expenditure and fatigue during level surface walking among subjects with hemiplegic shoulder subluxation. Objective: The objective of this study is to measure the amount of energy consumption during level surface walking among hemiplegic subjects having shoulder subluxation with modified bobath cuff. The objective of this study is to measure the fatigue of hemiplegic subjects having shoulder subluxation with modified bobath cuff. Subjects and method: 30 subjects with shoulder subluxation were included in this study by a convenient sampling method. The subjects were given with a modified bobath cuff. The cardiorespiratory parameters (VO2, VCO2, and energy expenditure) were measured using COSMED k4b2 and fatigue was measured using the MFI20 questionnaire. All the measurements were acquired before the use of bobath cuff and 2 weeks following the onset of bobath cuff use. Results: There was a significant difference between in cardiorespiratory functions the two conditions following the application of bobath cuff with p<0.05. There was a significant difference in general and mental fatigue but no difference was found in physical, reduced activity, and reduced motivation. Discussion and conclusion: The modified bobath cuff is significantly efficient in terms of energy expenditure and fatigue in subjects with shoulder subluxation.

Validation of the Cosmed K4b2 Portable Metabolic System During Running Outdoors

Ross, R, ALDuhishy, A, and González-Haro, C. Validation of the cosmed K4b2 portable metabolic system during running outdoors. J Strength Cond Res 34(1): 124-133, 2020-The aim of this study was to determine the agreement of the K4b metabolic system in comparison with the Douglas bags (DB) method for determining gas-exchange variables during both indoor treadmill and outdoor running. Nineteen endurance-trained males undertook 3 maximal incremental running tests, separated by at least 2 days: K4b indoor test (K1), K4b outdoor test (K2), and DB indoor test. Gas-exchange parameters (VO2, VCO2, VE, VI, Respiratory Exchange Ratio, FEO2, and FECO2) and heart rate were measured during K1, K2, and DB tests. For most of the variables (VO2, %VO2, %VCO2, VE, and VI), the agreement was better for K2 when compared with DB than for K1 when compared with DB. For VCO2, FEO2, and FECO2, the agreement was better between K1 when compared with DB than for K2 when compared with DB. Respiratory Exchange Ratio showed a similar agreement between both conditions (K1 vs. DB and K2 vs. DB). K4b seems valid for measuring gas-exchange variables during submaximal and maximal running velocities in an outdoor environment. Although K2 mean systematic error (bias) was low, the aleatory error was moderate. These considerations should be taken into account when using K4b to measure gas-exchange parameters both during indoor and outdoor activities.

Efficacy of a Goal Setting and Implementation Planning Intervention on Firefighters' Cardiorespiratory Fitness.

Bycura, DK, Dmitrieva, NO, Santos, AC, Waugh, KL, and Ritchey, KM. Efficacy of a Goal Setting and Implementation Planning Intervention on Firefighters' Cardiorespiratory Fitness. J Strength Cond Res 33(11): 3151-3161, 2019-The purpose of this study was to assess the effectiveness of a goal setting and implementation planning (GSIP) intervention on cardiorespiratory fitness among firefighters. Male career firefighters (N = 20) from a large municipal fire department were assigned to an intervention arm (n = 12) or passive control arm (n = 8) of a 14-week study involving cardiorespiratory exercise. The intervention consisted of GSIP coaching at baseline and support throughout the study. Cardiorespiratory fitness was assessed through a standardized physical protocol for firefighters (Candidate Physical Ability Test) at baseline, at 6 weeks, and at 14 weeks time points, using the Cosmed K4b portable metabolic system to measure physiological variables. Using intention-to-treat principles, we employed a 2-level multilevel model to examine the effect of intervention group on intercept and change over time on primary outcomes of interest: oxygen transport and utilization (VO2), heart rate (HR), and respiratory exchange ratio (R). Results demonstrated that the intervention and control groups both exhibited a significant increase in VO2 (B = 0.143, SE = 0.025, p < 0.001) and a decline in R (B = -0.003. SE = 0.001, p < 0.01) over the course of the study. Although both groups exhibited improvements on 2 of the 3 cardiorespiratory outcomes, subjects assigned to the intervention did not exhibit superior outcomes when compared to the control group. Given the improvements we observed in 2 out of 3 outcomes across both conditions, future research may consider testing effectiveness of interventions consisting of functional training exercises that closely translate to firefighting tasks over time periods sufficient to elicit aerobic metabolic adaptations.

Comparison of Indirect Calorimetry- and Accelerometry-Based Energy Expenditure During Children‘s Discrete Skill Performance

ABSTRACTPurpose: To compare children’s energy expenditure (EE) levels during object projection skill performance (OPSP; e.g., kicking, throwing, striking) as assessed by hip- and wrist-worn accelerometers. Method: Forty-two children (female n = 20, Mage = 8.1 ± 0.8 years) performed three, nine-minute sessions of kicking, over-arm throwing, and striking at performance intervals of 6, 12, and 30 seconds. EE was estimated using indirect calorimetry (COSMED k4b2) and accelerometers (ActiGraph GT3X+) worn on three different locations (hip, dominant-wrist, and non-dominant-wrist) using four commonly used cut-points. Bland-Altman plots were used to analyze the agreement in EE estimations between accelerometry and indirect calorimetry (METS). Chi-square goodness of fit tests were used to examine the agreement between accelerometry and indirect calorimetry. Results: Hip- and wrist-worn accelerometers underestimated EE, compared to indirect calorimetry, during all performance conditions. Skill practice at a rate of two trials per minute resulted in the equivalent of moderate PA and five trials per minute resulted in vigorous PA (as measured by indirect calorimetry), yet was only categorized as light and/or moderate activity by all measured forms of accelerometry. Conclusion: This is one of the first studies to evaluate the ability of hip- and wrist-worn accelerometers to predict PA intensity levels during OPSP in children. These data may significantly impact PA intervention measurement strategies by revealing the lack of validity in accelerometers to accurately predict PA levels during OPSP in children.

Peak Physiological Responses In Cycling And A New Underwater Swimming Test In Highly Trained Artistic Swimmers

PURPOSE: The purpose of this study was to compare peak oxygen uptake (VO2peak) measured in an underwater swim test (UWST) and during a maximal aerobic capacity test on a cycle ergometer (Velotron Pro, Seattle, WA, USA). METHODS: Highly trained artistic swimmers (n=14, 14.9 ± 1.9 yrs) completed a synchronised swimming specific test (275m UWST) in a 25m pool an incremental exercise test to volitional fatigue (15 W every 30 sec to exhaustion) on a cycle ergometer to determine VO2peak. The UWST and maximal aerobic capacity testing occurred on consecutive days. The 275m UWST comprised 50m freestyle followed by 25m underwater breast stroke three times, with an additional 50m freestyle. During the UWST participants wore water-resistant HR monitors (Polar OH1) and had expired gases collected (Cosmed K4 b2) in the 20 sec immediately upon completion of the UWST to determine VO2peak. During the cycle test, HR (Polar Electro, Kempele, Finland) and expired gases were collected using a MOXUS metabolic cart (AEI Technologies, Pittsburgh, PA, USA). Peak physical work capacity (PWC) (W) was measured as the highest completed 30 sec stage of the test. RESULTS: VO2peak achieved after the UWST (44.3 ± 8.0 mL/kg/min) and cycle ergometer (42.3 ± 7.2 mL/kg/min) did not differ significantly from each other (t=-0.59, df=13, p=0.563, d=0.21). HRpeak was significantly lower during the UWST (162.5 ± 18.4 bpm) (t=7.812, df=12, p<0.00, d=2.10) when compared to the cycle test (194.6 ± 11.6 bpm) . The UWST time and PWC during the bike test were not significantly correlated to each other (r=-0.25, p=0.393). There was no significant correlation between the VO2peak achieved during the UWST and the duration of the UWST (r=-0.39, p=0.17). HRpeak during the UWST was significantly correlated with the VO2peak (r=0.62 p=0.03 CI95 [38.93, 46.44]) and HRpeak achieved on the cycle ergometer (r=0.59, p=0.04 CI95 [188.79, 200.92]). CONCLUSIONS: The similarities in VO2 data during the UWST and VO2peak protocol suggest the UWST is a valid method of determining VO2peak in highly trained artistic swimmers. A goal when selecting a VO2 protocol is to mimic the demands of the sport. In this population, the UWST is likely better than the cycle ergometer, as the modality of swimming with breath holding more closely matches the demands of an artistic swim routine.

Peer-Reviewed Abstracts

Background/Purpose: The US Department of Health and Human Services recommends that children participate daily in 60 minutes of moderate to vigorous physical activity (MVPA). A threshold of >4.0 METs (metabolic equivalent of task) is considered MVPA in children. Physical education classes are ideal settings for the promotion of MVPA through the practice of continuous (walking, running) and discrete (kicking, throwing, striking) skills. Recent research in adults has determined the energy expenditure of discrete skill practice to be high while participants’ rate of perceived exertion (RPE) was low. The replication of this phenomenon in children would provide evidence for the inclusion of discrete skill practice in curricula aiming to promote MVPA. Thus, this study examined energy expenditure (METs), rate of perceived exertion (RPE), and level of fun during object projection skill performance (kicking, throwing, and striking) at three different practice intervals in children. Method: Children (N = 42, Mage = 8.1 ± 0.8 years) participated in three nine-minute experimental sessions where participants performed rounds of 5 kicks, 5 throws, and 5 strikes in blocked fashion, at three practice intervals (i.e., 30, 12, and 6 seconds). Each participant completed the three sessions in a randomized order. Participants were instructed to perform all trials with maximum effort and to report their RPE (1 “Not tired at all” – 10 “So tired, I can’t go anymore”) and level of fun (1 “Not fun at all” – 10 “The most fun I’ve ever had”) using 10-point scales. The average energy expenditure (METs) during minutes 4-8 of each nine-minute session were calculated using a COSMED K4b2 gas analyzer. Analysis/Results: Three one-way repeated measures ANOVAs for METs, RPE, and fun were conducted to examine differences across groups and sex. Data indicated a main effect for interval condition (F = 94.36, p < .001, η2 = 0.605) with decreased interval times between performance trials yielding significantly higher METs across conditions (4.5 ± 0.8, 6.3 ± 1.3, 8.3 ± 1.6 at 30-, 12-, 6-sec interval respectively). There also was a main effect for sex (F = 52.28, p < .001, η2 = 0.305), with boys demonstrating higher METs at each performance trial interval. RPE and fun analyses determined a main effect for each interval (RPE; F = 91.16, p < .001, fun; F = 96.61, p<.001) with no difference in gender at each interval. The average RPE responses were low (3.3 ± 1.8, 4.1 ± 2.2, and 4.9 ± 2.7 at 30-, 12- and 6-sec interval respectively) while average fun levels remained high (8.0 ± 1.4, 8.3 ± 1.4, and 8.7 ± 1.4 at 30-, 12-, 6-sec interval respectively). Conclusions: Results indicate that skill practice in all three interval conditions resulted in MVPA. Boys and girls reported equivalent low levels of RPE and high levels of fun. These data demonstrate that the practice of discrete skills yield high levels of energy expenditure (METs), low levels of perceived exertion, and high levels of fun. This study provides positive evidence for the inclusion of discrete skills in physical activity interventions and physical education curricula attempting to promote MVPA.