Assessing the effectiveness of Compare Assistant for improving intra-rater reliability of ultrasound-measured muscle thickness.

PURPOSE: Muscle thickness measured via ultrasound is commonly used to assess muscle size. The purpose of this study was to determine if the reliability of this measurement will improve if using the Compare Assistant tool, and whether this depends on technician experience and the muscle being assessed. METHODS: Individuals came to the laboratory for two visits each separated by 24 h. On day 1, two ultrasound images were taken on the individual's anterior upper arm (elbow flexors) and anterior lower leg (tibialis anterior) by two inexperienced and one experienced ultrasound technician. On day 2, three images were taken: (1) without looking at the previous images taken on day 1; (2) after re-examining the images taken on day 1, and (3) side-by-side with the images taken on day 1 via Compare Assistant. Bayes Factors (BF10) were used to provide evidence for the null (< 0.33) or alternative (> 3) hypotheses. RESULTS: There was no rater by measurement technique interaction (upper body: BF10 = 0.04, lower body: BF10 = 0.138), nor was there a main effect of measurement technique (upper body: BF10 = 0.052, lower body: BF10 = 0.331), indicating that reliability measures were not improved for either the upper body (CV%, no look: 2.92 vs. Compare Assistant: 2.87) or lower body (CV%, no look: 1.81 vs. Compare Assistant: 1.34) as a result of using Compare Assistant. CONCLUSION: The results of this study suggest that day-to-day reliability of muscle thickness measurement may be limited by random biological variability as opposed to technician error.

The impact of cuff width on perceptual responses during and following blood flow restricted walking exercise.

INTRODUCTION: An appropriate comparison of different cuff widths during blood flow restricted exercise requires that the cuffs are inflated to the same relative pressures. Narrow cuffs tend to be preferred and may reduce discomfort when applied during resistance exercise, but whether this is also true during walking exercise remains unknown. METHODS: Individuals completed two identical walking trials, once with 12-cm wide cuffs and once with 17-cm wide cuffs. Five 2-min walking bouts were completed at a speed of 50 m/min, with a 1-min rest period between sets. The restriction cuffs were inflated to 40% of the individuals' arterial occlusion pressure taken with each respective cuff. Individuals were asked to rate their discomfort, perceived exertion (RPE), and cuff preference. RESULTS: Twenty-seven individuals completed the study. The 12-cm cuff required a higher occlusion pressure which resulted in a higher absolute pressure applied (58 vs. 52 mm Hg; BF10  = 19 331.897). Whilst there was no difference in RPE values between cuffs (BF10  = 0.474), individuals reported greater discomfort when using the wider cuffs (2.3 vs. 1.7; BF10  = 252.786). The majority of individuals (63%) preferred to use the narrower cuff, whereas fewer preferred the wider cuff (26%) and even fewer did not have a preference (11%). DISCUSSION: Blood flow restricted walking exercise performed with narrower restriction cuffs appeared to reduce participant discomfort whilst also being preferred over that of wider cuffs. Future studies may wish to test the influence of different restrictive cuff widths on alterations in gait patterns during blood flow restricted walking exercise.