Reliability and Validity of Muscle Size and Quality Analysis Techniques.

OBJECTIVE: This study investigated reliability and validity of muscle cross-sectional area and echo intensity using an automatic image analysis program. METHODS: Twenty-two participants completed two data collection trials consisting of ultrasound imaging of the vastus lateralis (VL) at 10 and 12 MHz. Images were analyzed manually and with Deep Anatomical Cross-Sectional Area (DeepACSA). Reliability statistics (i.e., intraclass correlation coefficient [ICC] model 2,1, standard error of measure expressed as a percentage of the mean [SEM%], minimal differences [MD] values needed to be considered real) and validity statistics (i.e., constant error [CE], total error [TE], standard error of the estimate [SEE]) were calculated. RESULTS: Automatic analyses of ACSA and EI demonstrated good reliability (10 MHz: ICC2,1 = 0.83 - 0.90; 12 MHz: ICC2,1 = 0.87-0.88), while manual analyses demonstrated moderate to excellent reliability (10 MHz: ICC2,1 = 0.82-0.99; 12 MHz: ICC2,1 = 0.73-0.99). Automatic analyses of ACSA presented greater error at 10 (CE = -0.76 cm2, TE = 4.94 cm2, SEE = 3.65 cm2) than 12 MHz (CE = 0.17 cm2, TE = 3.44 cm2, SEE = 3.11 cm2). Analyses of EI presented greater error at 10 (CE = 3.35 a.u., TE = 2.70 a.u., SEE = 2.58 a.u.) than at 12 MHz (CE = 3.21 a.u., TE = 2.61 a.u., SEE = 2.34 a.u.). CONCLUSION: The results suggest the DeepACSA program may be less reliable compared to manual analysis for VL ACSA but displayed similar reliability for EI. In addition, the results demonstrated the automatic program had low error for 10 and 12 MHz.

Can segmental bioelectrical impedance be used as a measure of muscle quality?

Recent works have shown bioelectrical impedance spectroscopy (BIS) may assess tissue quality. The purpose of this project was to examine associations between ultrasound echo intensity (EI) of quadriceps muscles (vastus lateralis [VL], vastus medialis [VM], vastus intermedius [VI], rectus femoris [RF]) and BIS parameters (R0, R1, C, α, fp), and if the associations are specific to individual muscles or associated with a representation of the entire quadriceps. Twenty-two participants (age: 22 ± 4 years; BMI: 25.47 ± 3.26 kg/m2) participated in all study activities. Participants had transverse ultrasound scans of each individual quadriceps muscle taken at 25, 50, and 75 % of the muscle length to generate an average EI for the VL, VM, VI, and RF, which were further averaged to generate an EI for the entire quadriceps. For BIS, participants were seated with electrodes placed on the thigh to measure the segmental quadriceps. The Cole-impedance model parameters that best fit the BIS data for each participant was used for all analyses. Pearson's correlation coefficient (r) were calculated to determine associations between muscles' EI and BIS parameters. The results suggest averaged EI of individual VL, VM, VI, RF muscles and the average EI of the segmental quadriceps were significantly related to the R0, C, α metrics of the Cole-impedance model representing quadriceps segmental tissues. This supports that segmental BIS may be an appropriate technique for rapid evaluation of segmental muscle quality.

Climbing the Ranks: A Study of Firefighter Health Disparities.

The fire service command structure encompasses recruit, incumbent firefighter, and officer positions. The purpose of this study was to quantify the effect of rank (recruits, incumbent firefighters, and officers) on health and physical ability characteristics within the fire service. Retrospective data from thirty-seven recruits (age = 29 ± 5 yrs, BMI = 26.5 ± 2.3 kg/m2); eighty-two incumbent firefighters (age = 30 ± 7 yrs, BMI = 28.8 ± 4.3 kg/m2); and forty-one officers (age = 41 ± 6 yrs, BMI = 28.6 ± 4.3 kg/m2) from a single department were used. Participants completed body composition tests (i.e., body fat percentage [%BF] and body mass index [BMI]), an air consumption test (ACT), and cardiopulmonary exercise testing. The ACT consisted of 10 standardized tasks. Five separate one-way analyses of co-variance (ANCOVA) were calculated, accounting for age. Partial eta squared statistics were calculated and Bonferroni-corrected post-hoc analyses were employed. The results demonstrated a significant effect of rank on %BF (F = 9.61, p < 0.001, η2 = 0.10); BMI (F = 3.45, p = 0.02, η2 = 0.05); relative VO2MAX (F = 12.52, p < 0.001; η2 = 0.11); and HRMAX (F = 18.89, p < 0.001, η2 = 0.03), but not on ACT time (F = 0.71, p = 0.55, η2 = 0.01). These outcomes suggest there are variations in anthropometric and physiological metrics of health across firefighter ranks. Administrators should be aware how these markers of health may vary across firefighter ranks.