In vivo fascicle length measurements via B-mode ultrasound imaging with single vs dual transducer arrangements

Abstract

Ultrasonography is a useful technique to study muscle contractions in vivo, however larger muscles like vastus lateralis may be difficult to visualise with smaller, commonly used transducers. Fascicle length is often estimated using linear trigonometry to extrapolate fascicle length to regions where the fascicle is not visible. However, this approach has not been compared to measurements made with a larger field of view for dynamic muscle contractions. Here we compared two different single-transducer extrapolation methods to measure VL muscle fascicle length to a direct measurement made using two synchronised, in-series transducers. The first method used pennation angle and muscle thickness to extrapolate fascicle length outside the image (extrapolate method). The second method determined fascicle length based on the extrapolated intercept between a fascicle and the aponeurosis (intercept method). Nine participants performed maximal effort, isometric, knee extension contractions on a dynamometer at 10° increments from 50 to 100° of knee flexion. Fascicle length and torque were simultaneously recorded for offline analysis. The dual transducer method showed similar patterns of fascicle length change (overall mean coefficient of multiple correlation was 0.76 and 0.71 compared to extrapolate and intercept methods respectively), but reached different absolute lengths during the contractions. This had the effect of producing force-length curves of the same shape, but each curve was shifted in terms of absolute length. We concluded that dual transducers are beneficial for studies that examine absolute fascicle lengths, whereas either of the single transducer methods may produce similar results for normalised length changes, and repeated measures experimental designs.

Interactions between fascicles and tendinous tissues in gastrocnemius medialis and vastus lateralis during drop landing

“…The error for estimating fascicle with the extrapolation method has been reported to be 2%‐7% and could potentially be larger when considering the high speed of drop and ground contact intensity (>3 m/s at 75 cm). A recent study suggests that using two synchronized in‐series transducers could overcome this limit and avoid absolute fascicle lengths misestimation compared to extrapolated method . As previously reported with the single transducer method, the fascicle data set may not perfectly reflect fascicle behavior; however, it could be assumed that this method does not alter the effects of landing height and type (ie, “similar differences in muscle contraction dynamics within participants.”).…”

“…A recent study suggests that using two synchronized in‐series transducers could overcome this limit and avoid absolute fascicle lengths misestimation compared to extrapolated method . As previously reported with the single transducer method, the fascicle data set may not perfectly reflect fascicle behavior; however, it could be assumed that this method does not alter the effects of landing height and type (ie, “similar differences in muscle contraction dynamics within participants.”). In our study, we estimate tendinous tissues length changes from fascicle length estimation and lower limb joint angles.…”

Ultrasound-derived Biceps Femoris Long Head Fascicle Length: Extrapolation Pitfalls

“…technique cannot be implemented), the use of dual probe array (17) or multiple scan sites should be further investigated on BFlh.…”

The Effect of Cadence on the Mechanics and Energetics of Constant Power Cycling

“…A movement initiation threshold was set at 90% of the maximum isometric torque recorded at the 100 0 knee angle. and sample rate of 80 Hz, TELEMED, Vilnius, Lithuania) that were held end-to-end in a custom frame and secured to the lateral thigh (14). Markings were made on the skin with a semipermanent marker so the position of the transducers could be replicated for the cycling protocol.…”