Data from: Inferring muscle functional roles of the ostrich pelvic limb during walking and running using computer optimization

Owing to their cursorial background, ostriches (Struthio camelus) walk and
run with high metabolic economy, can reach very fast running speeds and
quickly execute cutting manoeuvres. These capabilities are believed to be
a result of their ability to coordinate muscles to take advantage of
specialized passive limb structures. This study aimed to infer the
functional roles of ostrich pelvic limb muscles during gait. Existing gait
data were combined with a newly developed musculoskeletal model to
generate simulations of ostrich walking and running that predict muscle
excitations, force and mechanical work. Consistent with previous avian
electromyography studies, predicted excitation patterns showed that
individual muscles tended to be excited primarily during only stance or
swing. Work and force estimates show that ostrich gaits are partially
hip-driven with the bi-articular hip–knee muscles driving stance
mechanics. Conversely, the knee extensors acted as brakes, absorbing
energy. The digital extensors generated large amounts of both negative and
positive mechanical work, with increased magnitudes during running,
providing further evidence that ostriches make extensive use of tendinous
elastic energy storage to improve economy. The simulations also highlight
the need to carefully consider non-muscular soft tissues that may play a
role in ostrich gait.