Eric V. Neufeld

Inter- and intra-rater agreement of static posture analysis using a mobile application

[Purpose] To determine the intra- and inter-rater agreement of a mobile application, PostureScreen Mobile® (PSM), that assesses static standing posture. [Subjects and Methods] Three examiners with different levels of experience of assessing posture, one licensed physical therapist and two untrained undergraduate students, performed repeated postural assessments of 10 subjects, fully clothed or minimally clothed, using PSM on two nonconsecutive days. Anterior and right lateral images were captured and seventeen landmarks were identified on them. Intraclass correlation coefficients (ICCs) were calculated for each of 13 postural measures to evaluate inter-rater agreement on the first visit (fully or minimally clothed), as well as intra-rater agreement between the first and second visits (minimally clothed). [Results] Eleven postural measures were ultimately analyzed for inter- and intra-rater agreement. Inter-rater agreement was almost perfect (ICC≥0.81) for four measures and substantial (0.60<ICC≤0.80) for three measures during the fully clothed exam. During the minimally clothed exam, inter-rater agreement was almost perfect for four measures and substantial for four measures. Intra-rater agreement between two minimally clothed exams was almost perfect for two measures and substantial for five measures. [Conclusion] PSM is a widely available, inexpensive postural screening tool that requires little formal training. To maximize inter- and intra-rater agreement, postural screening using this mobile application should be conducted with subjects wearing minimal clothing. Assessing static standing posture via PSM gives repeatable measures for anatomical landmarks that were found to have substantial or almost perfect agreement. Our data also suggest that this technology may also be useful for diagnosing forward head posture.

Wrist-worn triaxial accelerometry predicts the energy expenditure of non-vigorous daily physical activities

OBJECTIVES Triaxial accelerometry is commonly used to estimate oxygen uptake (VO2) and energy expenditure in health and fitness studies. We tested the correlation of a triaxial accelerometer in terms of a summation of vector magnitudes with gravity subtracted (SVMgs) and measured VO2 for different daily physical activities. DESIGN Original research, cross-sectional. METHODS Twenty volunteers wore a triaxial accelerometer on both wrists while performing 12 assigned daily physical activities for 6min for each activity. The VO2 was determined by indirect calorimetry using a portable metabolic measurement system. The last 3min of each activity was assumed to represent steady-state. The VO2 measured during these periods was averaged and converted into metabolic equivalents (METs). RESULTS The range of VO2 for all activities was 0.18-3.2L/min (0.8-12.2 METs). Significant differences in SVMgs existed between accelerometer placements on the dominant (120.9±8.7gmin) versus non-dominant hand (99.9±6.8gmin; P=0.016) for the lowest levels of physical activity defined as <1.5 METs. Piecewise linear regression model using 6 METs as the transition point showed similar significant correlations for the non-dominant wrist (r2=0.85; P<0.001) and the dominant wrist (r2=0.86; P<0.001). Using the non-dominant wrist below 6 METs, the slope of the relationship between SVMgs and METs was 105.3±4.3 (95% CI 96.9 to 113.7) indicating an increase in SVMgs of approximately 100 units for every MET increase in oxygen uptake. CONCLUSIONS Wrist-worn triaxial accelerometry reliably predicted energy expenditure during common physical activities <6 METs. More consistent correlations were found when the accelerometer was worn on the non-dominant wrist rather than the dominant wrist.

Exploratory Study of Heart Rate Variability and Sleep among Emergency Medical Services Shift Workers.

Abstract Objectives: To characterize the continuity and duration of sleep, and to measure nocturnal cardiac autonomic balance via heart rate variability (HRV) in a group of emergency medical technicians (EMTs) on and off duty. Methods: Fourteen EMTs completed an online, daily sleep log that recorded total sleep duration, bedtime, rise time, and the number of alarms that caused awakening. HRV was captured using a physiological status monitor (PSM) affixed to a chest strap during sleep. Results: For the 7-day trial, each of the 14 EMTs logged three work days (WDs) and four non-work days (NWDs). They reported sleeping significantly fewer hours per night on WDs (6.4 ± 2.1) than on NWDs (7.9 ± 0.5; P < 0.05), and experienced more sleep disruptions on WDs (4.4 ± 2.8) than on NWDs (1.3 ± 2.2; P < 0.001) as measured by the number of alarms. Global and vagal indices of HRV during sleep were significantly reduced during WDs (Standard Deviation of Normal R-R Intervals (SDNN) = 43.4 ± 2.0 ms and High Frequency (HF) = 24.3 ± 1.2 ms2) when compared to NWDs (SDNN = 61.1 ± 1.0 ms and HF = 42.7 ± 1.5 ms2; P < 0.001). Conclusion: EMTs who worked 24-hour shifts had shorter, more fragmented sleep associated with greater cumulative exposure to increased sympathetic and decreased parasympathetic activity as measured via sleep HRV. These changes in cardiac autonomic tone constitute one plausible pathway through which sleep deprivation may increase risk for cardiovascular disease.

Sleep deprivation and obesity in adults: a brief narrative review

Background/aims Obesity and sleep deprivation are two epidemics that pervade developed nations. Their rates have been steadily rising worldwide, especially in the USA. This short communication will explore the link between the two conditions and outline the proposed mechanisms behind their relationship. Methods Studies on the topic of sleep and obesity were reviewed, and findings were used to develop a theoretical model for the biological link between short sleep duration and obesity. Results Individuals who regularly slept less than 7  hours per night were more likely to have higher average body mass indexes and develop obesity than those who slept more. Studies showed that experimental sleep restriction was associated with increased levels of ghrelin, salt retention and inflammatory markers as well as decreased levels of leptin and insulin sensitivity. Conclusions There may be a link between obesity and sleep deprivation. We recommend further investigations are to elucidate the potential mechanisms.

Effect of altering breathing frequency on maximum voluntary ventilation in healthy adults

BackgroundCompared to other pulmonary function tests, there is a lack of standardization regarding how a maximum voluntary ventilation (MVV) maneuver is performed. Specifically, little is known about the variation in breathing frequency (fR) and its potential impact on the accuracy of test results. This study examines the effect of several preselected values for fR and one self-selected fR (fRself) on MVV.MethodsTen participants performed MVV maneuvers at various fR values, ranging from 50 to 130 breaths·min− 1 in 10 breaths·min− 1 intervals and at one fRself. Three identical trials with 2-min rest periods were conducted at each fR, and the sequence in which fR was tested was randomized. Ventilation and related parameters were measured directly by gas exchange analysis via a metabolic measurement system.ResultsA third-order polynomial regression analysis showed that MVV = − 0.0001(fR)3 + 0.0258(fR)2–1.38(fR) + 96.9 at preselected fR and increased up to approximately 100 breaths·min− 1 (r2 = 0.982, P < 0.001). Paired t-tests indicated that average MVV values obtained at all preselected fR values, but not fRself, were significantly lower than the average maximum value across all participants. A linear regression analysis revealed that tidal volume (VT) = − 2.63(MVV) + 300.4 at preselected fR (r2 = 0.846, P < 0.001); however, this inverse relationship between VT and MVV did not remain true for the self-selected fR. The VT obtained at this fR (90.9 ± 19.1% of maximum) was significantly greater than the VT associated with the most similar MVV value (at a preselected fR of 100 breaths·min− 1, 62.0 ± 10.4% of maximum; 95% confidence interval of difference: (17.5, 40.4%), P < 0.001).ConclusionsThis study demonstrates the shortcomings of the current lack of standardization in MVV testing and establishes data-driven recommendations for optimal fR. The true MVV was obtained with a self-selected fR (mean ± SD: 69.9 ± 22.3 breaths·min− 1) or within a preselected fR range of 110–120 breaths·min− 1. Until a comprehensive reference equation is established, it is advised that MVV be measured directly using these guidelines. If an individual is unable to perform or performs the maneuver poorly at a self-selected fR, ventilating within a mandated fR range of 110–120 breaths·min− 1 may also be acceptable.

Exercise responses in patients with chronically high creatine kinase levels: Exercise Response with High-CK

Elevated serum creatine kinase (CK) is often taken to reflect muscle disease, but many individuals have elevated CK without a specific diagnosis. How elevated CK reflects muscle metabolism during exercise is not known.

Corrigendum to “Interrelationship between Sleep and Exercise: A Systematic Review”

[This corrects the article DOI: 10.1155/2017/1364387.].