Rehabilitation Assessment System for Stroke Patients Based on Fusion-Type Optoelectronic Plethysmography Device and Multi-Modality Fusion Model: Design and Validation.

This study aimed to propose a portable and intelligent rehabilitation evaluation system for digital stroke-patient rehabilitation assessment. Specifically, the study designed and developed a fusion device capable of emitting red, green, and infrared lights simultaneously for photoplethysmography (PPG) acquisition. Leveraging the different penetration depths and tissue reflection characteristics of these light wavelengths, the device can provide richer and more comprehensive physiological information. Furthermore, a Multi-Channel Convolutional Neural Network-Long Short-Term Memory-Attention (MCNN-LSTM-Attention) evaluation model was developed. This model, constructed based on multiple convolutional channels, facilitates the feature extraction and fusion of collected multi-modality data. Additionally, it incorporated an attention mechanism module capable of dynamically adjusting the importance weights of input information, thereby enhancing the accuracy of rehabilitation assessment. To validate the effectiveness of the proposed system, sixteen volunteers were recruited for clinical data collection and validation, comprising eight stroke patients and eight healthy subjects. Experimental results demonstrated the system's promising performance metrics (accuracy: 0.9125, precision: 0.8980, recall: 0.8970, F1 score: 0.8949, and loss function: 0.1261). This rehabilitation evaluation system holds the potential for stroke diagnosis and identification, laying a solid foundation for wearable-based stroke risk assessment and stroke rehabilitation assistance.

Breathing Chest Wall Kinematics Assessment through a Single Digital Camera: A Feasibility Study.

The identification of respiratory patterns based on the movement of the chest wall can assist in monitoring an individual's health status, particularly those with neuromuscular disorders, such as hemiplegia and Duchenne muscular dystrophy. Thoraco-abdominal asynchrony (TAA) refers to the lack of coordination between the rib cage and abdominal movements, characterized by a time delay in their expansion. Motion capture systems, like optoelectronic plethysmography (OEP), are commonly employed to assess these asynchronous movements. However, alternative technologies able to capture chest wall movements without physical contact, such as RGB digital cameras and time-of-flight digital cameras, can also be utilized due to their accessibility, affordability, and non-invasive nature. This study explores the possibility of using a single RGB digital camera to record the kinematics of the thoracic and abdominal regions by placing four non-reflective markers on the torso. In order to choose the positions of these markers, we previously investigated the movements of 89 chest wall landmarks using OEP. Laboratory tests and volunteer experiments were conducted to assess the viability of the proposed system in capturing the kinematics of the chest wall and estimating various time-related respiratory parameters (i.e., fR, Ti, Te, and Ttot) as well as TAA indexes. The results demonstrate a high level of agreement between the detected chest wall kinematics and the reference data. Furthermore, the system shows promising potential in estimating time-related respiratory parameters and identifying phase shifts indicative of TAA, thus suggesting its feasibility in detecting abnormal chest wall movements without physical contact with a single RGB camera.

Challenges in body composition assessment using air-displacement plethysmography by BOD POD in pediatric and young adult patients.

BACKGROUND & AIMS: Air-Displacement-Plethysmography (ADP) by BOD POD is widely used for body fat assessment in children. Although validated in healthy subjects, studies about use in pediatric patients are lacking. We evaluated user experience and usability of ADP measurements with the BOD POD system in healthy children and pediatric and young adult patients. METHODS: Using the experiences of seven cohort studies, which included healthy children and patients aged 2-22 years, we retrospectively evaluated the user experience with the User Experience Questionnaire (UEQ) (n = 13) and interviews (n = 7). Technical performance was studied using the quality control data collected by the ADP-system. RESULTS: From 2016 to 2022, 1606 measurements were scheduled. BOD POD was mostly rated 'user-friendly', with a generally neutral evaluation on all scales of the UEQ. However, questionable reliability and validity of the results were frequently (86%) reported. We found a high technical failure-rate of the device, predominantly in stability (17%) and accuracy of the measurement (12%), especially in the 'pediatric option' for children aged <6 years. Measurement failure-rate was 38%, mostly due to subject's fear or device failure, especially in young and lean children, and in children with physical and/or intellectual disabilities. CONCLUSION: We conclude that ADP by BOD POD in children and young adults is non-invasive and user-friendly. However, in specific pediatric populations, BOD POD has several limitations and high (technical) failure-rates, especially in young children with aberrant body composition. We recommend caution when interpreting body composition results of pediatric patients as assessed with BOD POD using the current default settings.

Energy Expenditure Estimation From Respiratory Magnetometer Plethysmography: A Comparison Study.

Physical activity (PA) quantification by estimating energy expenditure (EE) is essential to health. Reference methods for EE estimation often involve expensive and cumbersome systems to wear. To address these problems, light-weighted and cost-effective portable devices are developed. Respiratory magnetometer plethysmography (RMP) is among such devices, based on the measurements of thoraco-abdominal distances. The aim of this study was to conduct a comparative study on EE estimation with low to high PA intensity with portable devices including the RMP. Fifteen healthy subjects aged 23.84±4.36 years were equipped with an accelerometer, a heart rate (HR) monitor, a RMP device and a gas exchange system, while performing 9 sedentary and physical activities: sitting, standing, lying, walking at 4 and 6 km/h, running at 9 and 12 km/h, biking at 90 and 110 W. An artificial neural network (ANN) as well as a support vector regression algorithm were developed using features derived from each sensor separately and jointly. We compared also three validation approaches for the ANN model: leave one out subject, 10 fold cross-validation, and subject-specific. Results showed that 1. for portable devices the RMP provided better EE estimation compared to accelerometer and HR monitor alone; 2. combining the RMP and HR data further improved the EE estimation performances; and 3. the RMP device was also reliable in EE estimation for various PA intensities.

Energy Expenditure Estimation in Children, Adolescents and Adults by Using a Respiratory Magnetometer Plethysmography System and a Deep Learning Model.

PURPOSE: Energy expenditure is a key parameter in quantifying physical activity. Traditional methods are limited because they are expensive and cumbersome. Additional portable and cheaper devices are developed to estimate energy expenditure to overcome this problem. It is essential to verify the accuracy of these devices. This study aims to validate the accuracy of energy expenditure estimation by a respiratory magnetometer plethysmography system in children, adolescents and adults using a deep learning model. METHODS: Twenty-three healthy subjects in three groups (nine adults (A), eight post-pubertal (PP) males and six pubertal (P) females) first sat or stood for six minutes and then performed a maximal graded test on a bicycle ergometer until exhaustion. We measured energy expenditure, oxygen uptake, ventilatory thresholds 1 and 2 and maximal oxygen uptake. The respiratory magnetometer plethysmography system measured four chest and abdomen distances using magnetometers sensors. We trained the models to predict energy expenditure based on the temporal convolutional networks model. RESULTS: The respiratory magnetometer plethysmography system provided accurate energy expenditure estimation in groups A (R2 = 0.98), PP (R2 = 0.98) and P (R2 = 0.97). The temporal convolutional networks model efficiently estimates energy expenditure under sitting, standing and high levels of exercise intensities. CONCLUSION: Our results proved the respiratory magnetometer plethysmography system's effectiveness in estimating energy expenditure for different age populations across various intensities of physical activity.

Evaluation of a novel probe based on laser Doppler flowmetry and comparison with photo plethysmography for assessment of the skin perfusion pressure.

This study aims to compare skin perfusion pressure measurements (SPP) at midfoot and below knee level performed with a novel laser Doppler flowmetry (LD) probe with a reference method based on photo plethysmography (PP). It includes 40 patients referred with known or suspected peripheral arterial disease. The SPP was performed with both devices. Blinded re-interpretation of the SPP measurements was carried out by three observers and a consensus quality score was provided for each measurement. SPP >40 mmHg was considered a clinically relevant cut-off. This study evaluates a total of 48 paired measurements of the midfoot and 54 below knee. The two methods agreed in overall diagnostic classification in 80 of 102 measurements (78%) with both methods showing SPP ≥40 mmHg in 21 cases, and both methods showing SPP <40 mmHg in 59 cases. Of the 22 participants with disagreement (22%) in overall classification, 15 had measurements within the range of 30-50 mmHg, and 7 with a clinically relevant disagreement with one device showing SPP <30 mmHg and the other ≥40 mmHg. Analysis of inter observer variation for the LD readings showed an intraclass correlation coefficient of 0.880 (95% CI: 0.807 to 0.929, p- value <0.05) at midfoot, and 0.933 (95% CI: 0.894 to 0.959, p-value <0.05) at below knee level. The novel probe based on LD showed good correlation with PP in absolute pressures, sufficient agreement in overall disease classification as well as good to excellent reliability in terms of inter observer variation.

Body Composition Assessment in Mexican Children and Adolescents. Part 1: Comparisons between Skinfold-Thickness, Dual X-ray Absorptiometry, Air-Displacement Plethysmography, Deuterium Oxide Dilution, and Magnetic Resonance Imaging with the 4-C Model.

The evaluation of body composition (BC) is relevant in the evaluation of children's health-disease states. Different methods and devices are used to estimate BC. The availability of methods and the clinical condition of the patient usually defines the ideal approach to be used. In this cross-sectional study, we evaluate the accuracy of different methods to estimate BC in Mexican children and adolescents, using the 4-C model as the reference. In a sample of 288 Mexican children and adolescents, 4-C body composition assessment, skinfold-thickness (SF), dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), and deuterium dilution (D2O) were performed, along with MRI in a subsample (52 participants). The analysis of validity was performed by correlation analysis, linear regression, and the Bland-Altman method. All methods analyzed showed strong correlations for FM with 4-C values and between each other; however, DXA and MRI overestimated FM, whereas skinfolds and ADP under-estimated FM. Conclusion: The clinical assessment of BC by means of SF, ADP, DXA, MRI and D2O correlated well with the 4-C model and between them, providing evidence of their clinical validity and utility. The results from different methods are not interchangeable. Preference between methods may depend on their availability and the specific clinical setting.

Implications of face mask use on body composition assessment by air-displacement plethysmography.

BACKGROUND & AIMS: The BOD POD (COSMED USA Inc., Concord, CA) is a common instrument used to assess body composition by employing air displacement plethysmography and whole-body densitometry to determine body volume. This instrument requires isothermal conditions during testing; therefore, the introduction of outside isothermal air can impact testing results. With the COVID-19 pandemic introducing face mask mandates, it is unknown whether the use of a face mask during BOD POD testing may lead to erroneous measurement by introducing isothermal air. Thus, the purpose of this cross-sectional study was to investigate the impact of wearing a surgical face mask compared to not wearing a surgical face mask on body composition assessment among adults. METHODS: During testing, female subjects were required to wear a swimsuit or form-fitting lycra shorts and a sports bra and male subjects were required to wear form-fitting lycra shorts. American Society for Testing and Materials (ASTM) level one surgical face masks (bacterial and particulate filtration efficiency of 95%) and standard swim caps were provided by researchers. Variables of interest included percent body fat, body fat, percent lean body mass, and lean body mass. Participants (n = 33) completed one test wearing a mask and one test without a mask back-to-back with conditions held constant. Dependent-sample sign tests, Bland-Altman Plots, and Passing-Bablok regression analyses were used to test mask-on versus mask-off differences and agreement between variables of interest. RESULTS: There were no significant median differences in any body composition results between face mask use and non-face mask use using dependent-sample sign tests. Bland-Altman Plots demonstrated acceptable agreement between mask usage and non-mask usage. No significant differences were seen in the slopes of the variables using Passing-Bablok regression. CONCLUSIONS: Results suggest that wearing a face mask does not appreciably impact body composition results. Therefore, ASTM level 1 disposable surgical face mask does not introduce a significant amount of isothermal air during BOD POD testing.

The use of strain-gauge plethysmography in the functional assessment of chronic venous disease: five-year experience at a single centre.

OBJECTIVE: Plethysmography can be used in the diagnosis and evaluation of chronic venous disease in the lower extremities. This study aimed to evaluate the applicability and reliability of strain-gauge plethysmography (SDP) in the functional assessment of chronic venous disease. METHODS: This descriptive study was conducted between 2016 and 2021 at a single centre. Four hundred and thirty-two patients with symptomatic chronic venous disease were included in the study. All participants were diagnosed initially with Doppler ultrasonography. SGP was then performed to evaluate venous outflow capacity, venous reflux and muscle pump function. RESULTS: The average age was 45.16 ± 12.54 years (median age 46 years; range 20-78 years), and 239 (55.3%) women and 193 (44.7%) men were included in the study. The age groups, diagnosis, pathological distribution and risk factors were quantitatively determined according to gender. Localisation and lateralisation statistics of the pathologies are given. SGP measurements, including venous volume (V), venous emptying (VE), expelled volume ratio in four seconds (EV4/V), half refilling time (t½) and refilling volume (RV) of each lower extremity, were done individually to compare the involved extremity with the normal contralateral side. SGP measurements of each affected lower limb were also compared separately by gender, age group and disease onset. The correlation between t½ values and skin discolouration or oedema of the affected limb was examined. Finally, receiver operating characteristic curve analyses of the V, VE, EV4/V, t½ and RV values were done, and the cut-off values of each parameter were defined accordingly. CONCLUSION: High reliability and consistent results indicate that SGP is a practical and sensitive test for quantitative functional assessment of patients with chronic venous disease. It can be used as an effective method in diagnosing and following up chronic venous disorders. As there are no currently accepted cut-off values, we suggest that ours can be used as new reference values for SGP measurements.

Body composition assessment after pediatric liver transplant.

BACKGROUND: Pediatric liver transplantation generally restores metabolic function; yet after transplantation, some children remain malnourished, have increased adiposity, and develop obesity. Measurement of body composition in the assessment of nutrition status could reduce adverse consequences in children. METHODS: Anthropometric measurements, multiple-frequency bioelectrical impedance analysis, air displacement plethysmography, and ultrasound measurements were conducted on children recruited from the liver transplant program at the University of Minnesota Masonic Children's Hospital. A cross-sectional study was conducted to describe the quality of weight gain in post-liver transplant children between the ages of 2 and 17 years using multiple assessment tools (air displacement plethysmography, multiple-frequency bioelectrical impedance analysis, and ultrasound) and to determine whether multiple-frequency bioelectrical impedance analysis and ultrasound accurately describe body composition and quality of weight gain. RESULTS: Mean percent body fat by air displacement plethysmography and multiple-frequency bioelectrical impedance analysis was 18.4% (±3.3) and 19.0% (±3.9), respectively (P > .99). There were insufficient data to examine the relationship between summed muscle and adipose thickness measures by ultrasound and percent body fat determined by air displacement plethysmography or multiple-frequency bioelectrical impedance analysis. CONCLUSION: Percent body fat, fat mass, and fat-free mass measures determined by air displacement plethysmography and multiple-frequency bioelectrical impedance analysis were not statistically different, which suggests the stand-on device used in this study could be a useful body composition assessment tool for the pediatric population.

Plethysmographic assessment of tidal expiratory flow limitation.

Chronic obstructive pulmonary disease (COPD) patients often experience tidal expiratory flow-limitation (tEFL), a condition causing respiratory and cardiovascular detrimental effects. As the appearance of tEFL should increase expiratory (Rexp) relative to inspiratory (Rins) resistance, we hypothesized that Rexp/Rins can be used to detect tEFL. Rexp/Rins was measured with a commercial plethysmograph in 109 healthy subjects and, before and after bronchodilation (BD), in 64 COPD patients, 36 with and 28 without tEFL according to the NEP technique. Before BD, the median (interquartile range) of Rexp/Rins was significantly greater (P < 0.001) in COPD patients with tEFL (2.47(3.06;7.07)) than in COPD patients without tEFL (1.63(1.44;1.82)) and in healthy subjects (1.52(1.35;1.62)). In COPD patients Rexp/Rins above 1.98 predicted the presence of tEFL with 96 % specificity and 92 % sensitivity, Rexp2/Rins performing even better. After BD the predictive ability of Rexp/Rins slightly declined, but remained elevated. The non-invasive measurement of Rexp/Rins is an easy, inexpensive, routinely usable method to detect tEFL in spontaneously breathing COPD subjects.

Reliability of Repeated Trials Protocols for Body Composition Assessment by Air Displacement Plethysmography.

Air displacement plethysmography (ADP) is fast, accurate, and reliable. Nevertheless, in about 3% of the cases, standard ADP tests provide rogue results. To spot these outliers and improve precision, repeated trials protocols have been devised, but few works have addressed their reliability. This study was conducted to evaluate the test-retest reliabilities of two known protocols and a new one, proposed here. Ninety-two healthy adults (46 men and 46 women) completed six consecutive ADP tests. To evaluate the reliability of single measurements, we used the results of the first two tests; for multiple measures protocols, we computed the test result from trials 1-3 and the retest result from trials 4-6. Bland-Altman analysis revealed that the bias and the width of the 95% interval of agreement were smaller for multiple trials than for single ones. For percent body fat (%BF)/fat-free mass, the technical error of measurement was 1% BF/0.68 kg for single trials and 0.62% BF/0.46 kg for the new protocol of multiple trials, which proved to be the most reliable. The minimal detectable change (MDC) was 2.77% BF/1.87 kg for single trials and 1.72% BF/1.26 kg for the new protocol.

Respiratory function assessment at the time of a new respiratory virus pandemic.

We must be aware that new respiratory virus pandemic can happen frequently. Standard lung function tests should keep their crucial role to assist the clinicians in the decision-making process, but they are at risk for the spread of infection because of the generated droplets. We used opto-electronic plethysmography to investigate the post-COVID-19 syndrome on 12 patients after ICU. We found normal ventilatory pattern at rest, a restrictive pattern located in the ribcage during vital capacity and surgical mask to significantly increase minute ventilation. The attention on unconventional respiratory function tests should be sponsored for the important information they can provide.

Infant body composition assessment in the neonatal intensive care unit (NICU) using air displacement plethysmography: Strategies for implementation into clinical workflow.

Nutritional management is integral to infant care in the neonatal intensive care unit (NICU). Recent research on body composition that specifically evaluated fat and fat-free mass has improved our understanding of infant growth and nutritional requirements. The need for body composition monitoring in infants is increasingly recognized as changes in fat mass and fat-free mass associated with early growth can impact clinical outcomes. With the availability of air displacement plethysmography (ADP) as a noninvasive method for assessing infant body composition and published normative gestational age- and sex-specific body composition curves, it is justifiable to integrate this innovation into routine clinical care. Here we describe our experiences in implementing body composition measurement using ADP in routine clinical care in different NICU settings.

Assessment of respiratory effort with EMG extracted from ECG recordings during prolonged breath holds: Insights into obstructive apnea and extreme physiology.

Breath holding divers display extraordinary voluntary control over involuntary reactions during apneic episodes. After an initial easy phase to the breath hold, this voluntary control is applied against the increasing involuntary effort to inspire. We quantified an electromyographic (EMG) signal associated with respiratory movements derived from broad bandpass ECG recordings taken from experienced breath holding divers during prolonged dry breath holds. We sought to define their relationship to involuntary respiratory movements and compare these signals with what is known to occur in obstructive sleep apnea (OSA) and epileptic seizures. ECG and inductance plethysmography records from 14 competitive apneists (1 female) were analyzed. ECG records were analyzed for intervals and the EMG signal was extracted from a re-filtered version of the original broad bandpass signal and ultimately enveloped with a Hilbert transform. EMG burst magnitude, quantified as an area measure, increased over the course of the struggle phase, correlated with inductance plethysmography measures, and corresponded to significant variance in heart rate variability. We conclude that an EMG signal extracted from the ECG can complement plethysmography during breath holds and may help quantify involuntary effort, as reported previously for obstructive sleep apnea. Further, given the resemblance between cardiac and respiratory features of the breath hold struggle phase to obstructive apnea that can occur during sleep or in association with epileptic seizure activity, the struggle phase may be a useful simulation of obstructive apnea for controlled experimentation that can help clarify aspects of acute and chronic apnea-associated physiology.

Validation of bioelectrical impedance analysis for body composition assessment in children with obesity aged 8-14y.

BACKGROUND & AIMS: The aim was to generate a predictive equation to assess body composition (BC) in children with obesity using bioimpedance (BIA), and avoid bias produced by different density levels of fat free mass (FFM) in this population. METHODS: This was a cross-sectional validation study using baseline data from a randomized intervention trial to treat childhood obesity. Participants were 8 to 14y (n = 315), underwent assessments on anthropometry and BC through Air Displacement Plethysmography (ADP), Dual X-Ray Absorptiometry and BIA. They were divided into a training (n = 249) and a testing subset (n = 66). In addition, the testing subset underwent a total body water assessment using deuterium dilution, and thus obtained results for the 4-compartment model (4C). A new equation to estimate FFM was created from the BIA outputs by comparison to a validated model of ADP adjusted by FFM density in the training subset. The equation was validated against 4C in the testing subset. As reference, the outputs from the BIA device were also compared to 4C. RESULTS: The predictive equation reduced the bias from the BIA outputs from 14.1% (95%CI: 12.7, 15.4) to 4.6% (95%CI: 3.8, 5.4) for FFM and from 18.4% (95%CI: 16.9, 19.9) to 6.4% (95% CI: 5.3, 7.4) for FM. Bland-Altman plots revealed that the new equation significantly improved the agreement with 4C; furthermore, the observed trend to increase the degree of bias with increasing FM and FFM also disappeared. CONCLUSION: The new predictive equation increases the precision of BC assessment using BIA in children with obesity.

A novel algorithm for minute ventilation estimation in remote health monitoring with magnetometer plethysmography.

PURPOSE: The purpose of this study was to evaluate the accuracy of minute ventilation (V˙E) estimation using a novel method based on a non-linear algorithm coupled with cycle-based features. The experiment protocol was well adapted for remote health monitoring applications by exploiting data streams from respiratory magnetometer plethysmography (RMP) during different physical activity (PA) types. Methods Thirteen subjects with an age distribution of 24.1±3.4 years performed thirteen PA ranging from sedentary to moderate intensity (walking at 4 and 6 km/h, running at 9 and 12 km/h, biking at 90 W and 110 W). In total, 3359 temporal segments of 10s were acquired using the Nomics RMP device while the iWorx spirometer was used for reference V˙E measurements. An artificial neural network (ANN) model based on respiration features was used to estimate V˙E and compared to the multiple linear regression (MLR) model. We also compared the subject-specific approach with the subject-independent approach. Results The ANN model using subject-specific approach achieved better accuracy for the V˙E estimation. The bias was between 0.20±0.87 and 0.78±3 l/min with the ANN model as compared to 0.73±3.19 and 4.17±2.61 l/min with the MLR model. Conclusion Our results demonstrated the pertinence of processing data streams from wearable RMP device to estimate the V˙E with sufficient accuracy for various PA types. Due to its low-complexity and real-time algorithm design, the current approach can be easily integrated into most remote health monitoring applications coupled with wearable sensors.

Five-component model validation of reference, laboratory and field methods of body composition assessment.

This study reports the validity of body fat percentage (BF%) estimates from several commonly employed techniques as compared with a five-component (5C) model criterion. Healthy adults (n 170) were assessed by dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), multiple bioimpedance techniques and optical scanning. Output was also used to produce a criterion 5C model, multiple variants of three- and four-component models (3C; 4C) and anthropometry-based BF% estimates. Linear regression, Bland-Altman analysis and equivalence testing were performed alongside evaluation of the constant error (CE), total error (TE), se of the estimate (SEE) and coefficient of determination (R2). The major findings were (1) differences between 5C, 4C and 3C models utilising the same body volume (BV) and total body water (TBW) estimates are negligible (CE ≤ 0·2 %; SEE < 0·5 %; TE ≤ 0·5 %; R2 1·00; 95 % limits of agreement (LOA) ≤ 0·9 %); (2) moderate errors from alternate TBW or BV estimates in multi-component models were observed (CE ≤ 1·3 %; SEE ≤ 2·1 %; TE ≤ 2·2 %; R2 ≥ 0·95; 95 % LOA ≤ 4·2 %); (3) small differences between alternate DXA (i.e. tissue v. region) and ADP (i.e. Siri v. Brozek equations) estimates were observed, and both techniques generally performed well (CE < 3·0 %; SEE ≤ 2·3 %; TE ≤ 3·6 %; R2 ≥ 0·88; 95 % LOA ≤ 4·8 %); (4) bioimpedance technologies performed well but exhibited larger individual-level errors (CE < 1·0 %; SEE ≤ 3·1 %; TE ≤ 3·3 %; R2 ≥ 0·94; 95 % LOA ≤ 6·2 %) and (5) anthropometric equations generally performed poorly (CE 0·6- 5·7 %; SEE ≤ 5·1 %; TE ≤ 7·4 %; R2 ≥ 0·67; 95 % LOA ≤ 10·6 %). Collectively, the data presented in this manuscript can aid researchers and clinicians in selecting an appropriate body composition assessment method and understanding the associated errors when compared with a reference multi-component model.

Short-Term Precision Error of Body Composition Assessment Methods in Resistance-Trained Male Athletes.

Athletic populations require high-precision body composition assessments to identify true change. Least significant change determines technical error via same-day consecutive tests but does not integrate biological variation, which is more relevant for longitudinal monitoring. The aim of this study was to assess biological variation using least significant change measures from body composition methods used on athletes, including surface anthropometry (SA), air displacement plethysmography (BOD POD), dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance spectroscopy (BIS). Thirty-two athletic males (age = 31 ± 7 years; stature = 183 ± 7 cm; mass = 92 ± 10 kg) underwent three testing sessions over 2 days using four methods. Least significant change values were calculated from differences in Day 1 Test 1 versus Day 1 Test 2 (same-day precision), as well as Day 1 Test 1 versus Day 2 (consecutive-day precision). There was high agreement between same-day and consecutive-day fat mass and fat-free mass measurements for all methods. Consecutive-day precision error in comparison with the same-day precision error was 50% higher for fat mass estimates from BIS (3,607 vs. 2,331 g), 25% higher from BOD POD (1,943 vs. 1,448 g) and DXA (1,615 vs. 1,204 g), but negligible from SA (442 vs. 586 g). Consecutive-day precision error for fat-free mass was 50% higher from BIS (3,966 vs. 2,276 g) and SA (1,159 vs. 568 g) and 25% higher from BOD POD (1,894 vs. 1,450 g) and DXA (1,967 vs. 1,461 g) than the same-day precision error. Precision error in consecutive-day analysis considers both technical error and biological variation, enhancing the identification of small, yet significant changes in body composition of resistance-trained male athletes. Given that change in physique is likely to be small in this population, the use of DXA, BOD POD, or SA is recommended.