Two Methods for Estimating Tendinous Tissue Elongation during Human Movement

Abstract

During dynamic activities it is difficult to assess in vivo length changes in human tendon and aponeurosis. The present study compared the outcome of two methods during unilateral squat jump and drop jump performances of four volunteers. Tendinous tissue elongation of vastus lateralis muscle was estimated using either (a) direct measurement of in vivo fascicle length change and muscletendon length estimation (kinematic method), or (b) prediction using a quadratic force function in combination with direct tendon force measurement (force method). In the kinematic method the most critical measures contributing to the 10% uncertainty were the fascicle angle and fraction of the estimated fascicle length. The force method was most sensitive to resting length, with 1% error margin. Both methods predicted the same pattern of tendinous elongation because of the monotonic force/length relationship. The magnitude of length change, however, differed considerably between both methods. Based on the force method, the changes were only 20% (absolute values) or 30% (strain values) of those obtained with the kinematic method. On average, the maximum strains were 5% with the force method and 15% with the kinematic method. This difference can be explained by the fact that the kinematic method characterizes not only the changes in tendon length but also includes aponeurosis strain along the muscle belly. In addition, the kinematic method may be affected by non-uniform distribution of fascicle length change along the length of the muscle. When applying either method for estimating the patterns of tendon and tendinous tissue length changes during human locomotion, the given methodological considerations should be acknowledged.

In vivomuscle functionvsspeed I. Muscle strain in relation to length change of the muscle-tendon unit

“…However, in some cases the tendon is reported to be more compliant than the aponeurosis . While there have been no direct studies of series elasticity in the equine vastus lateralis, there is substantial strain in the elastic elements of the human vastus lateralis Fukunaga et al, 2002;Ichinose et al, 2000;Muraoka et al, 2001) and at least one study (Finni and Komi, 2002) supports the idea that, in muscles in general, the aponeurosis may be more compliant than the tendon (Kawakami and Lieber, 2000). In the absence of data on the compliance of the series elasticity of the equine vastus lateralis, we cannot unambiguously account for the differences in observed and predicted strain.…”

In vivo assessment of muscle fascicle length by extended field-of-view ultrasonography

“…It has been shown previously that the error in estimating VL L f using trigonometric extrapolation was 2-7% (10) and 5.9% (15), which was considerably lower than found in the present study (12.6 Ϯ 8.1%). This discrepancy might be attributable to the present use of EFOV US imaging, with which it was possible to make direct comparisons (we measured the length of the same fascicle using both methods), or to comparisons in other studies being done at different muscle lengths and contraction intensities where aponeurosis and fascicle curvature was different (10,15). Regardless, the present data and those of others have revealed substantial inaccuracies in the estimation method, which in some circumstances may be of a magnitude greater than the longitudinal changes in L f reported previously (5, 28 -31).…”

Vastus lateralis exhibits non‐homogenous adaptation to resistance training

“…One of the limitations in this study is that fascicle length was not measured directly. Due to the time commitments of the athletes and the time‐intensive nature of direct measure, trigonometric estimation of FL was favored in line with the findings of previous research . However, previous research has suggested that a degree of curvature exists in both the fascicle and the aponeuroses of the muscle .…”