Meeting Abstract

6.3  Wednesday, Jan. 4  In vivo strain patterns indicate different functions in the proximal and distal fascia lata of the goat ENG, CM*; LIEBERMAN, DE; BIEWENER , AA; Harvard University, Cambridge, MA; Harvard University, Cambridge, MA; Harvard University, Cambridge, MA cmeng@fas.harvard.edu

We examined strain patterns in the fascia lata (FL), a large sheet of fascia overlying the lateral thigh of goats (Capra hircus), to assess its role in mediating elastic energy savings for limb swing in relation to its role in stance. At the beginning of swing, the limb is retracted and decelerated and then reaccelerated to swing the limb forward. The energy in the decelerating limb could therefore be stored elastically and recovered to reaccelerate the limb. Although stance phase elastic energy storage has been well studied, the role of energy storage during swing has received less attention. Sonomicrometry crystals were implanted in the proximal and distal FL to obtain biaxial strains (longitudinal and transverse). Using sonomicrometry and EMG, we also examined how the tensor fascia lata muscle (TFL) contracts to transmit force via the proximal border of the FL and how the gluteobiceps (GB) contracts to transmit force via the distal, posterior border of the FL. These muscles are both knee extensors but TFL flexes the hip while GB extends the hip. During trotting and galloping, the distal FL stretches biaxially through the stance-swing transition and then shortens after initial swing consistent with its role in elastic energy recovery for limb swing. While the distal FL stretches GB actively shortens, indicating that the distal FL is stretched by active GB contraction. Conversely, maximal stretch in the proximal FL occurs during stance prior to swing. Activity and strain patterns in TFL are not as well matched with proximal FL compared to GB and distal FL. These results indicate that: 1) the proximal and distal FL may serve different functions during locomotion and 2) the distal FL has the potential to store and recover elastic energy during swing phase.