Mechanics of running by quail ( Coturnix )

106

SUMMARYTake-off mechanics are fundamental to the ecology and evolution of flying animals. Recent research has revealed that initial takeoff velocity in birds is driven mostly by hindlimb forces. However, the contribution of the wings during the transition to air is unknown. To investigate this transition, we integrated measurements of both leg and wing forces during take-off and the first three wingbeats in zebra finch (Taeniopygia guttata, body mass 15g, N7) and diamond dove (Geopelia cuneata, body mass 50g, N3). We measured ground reaction forces produced by the hindlimbs using a perch mounted on a force plate, whole-body and wing kinematics using high-speed video, and aerodynamic forces using particle image velocimetry (PIV). Take-off performance was generally similar between species. When birds were perched, an acceleration peak produced by the legs contributed to 85±1% of the whole-body resultant acceleration in finch and 77±6% in dove. At lift-off, coincident with the start of the first downstroke, the percentage of hindlimb contribution to initial flight velocity was 93.6±0.6% in finch and 95.2±0.4% in dove. In finch, the first wingbeat produced 57.9±3.4% of the lift created during subsequent wingbeats compared with 62.5±2.2% in dove. Advance ratios were <0.5 in both species, even when taking self-convection of shed vortices into account, so it was likely that wing-wake interactions dominated aerodynamics during wingbeats 2 and 3. These results underscore the relatively low contribution of the wings to initial take-off, and reveal a novel transitional role for the first wingbeat in terms of force production. Supplementary material available online at

Section: Discussioncontrasting

confidence: 45%

Transition from leg to wing forces during take-off in birds

Provini

Tobalske

Crandell

et al. 2012

106

“…During stance, the orientation of the ground reaction force shifts from knee extension early in stance to knee flexion in midthrough late stance (Clark and Alexander, 1975;Roberts et al, 1998) (R.L.M. and J. Rubenson, unpublished observations).…”

Section: Coactivation Of the Fclp And Fclamentioning

confidence: 99%

The mechanical function of linked muscles in the guinea fowl hind limb

Ellerby

Marsh

2010

SUMMARYAlthough mechanical linkages between the proximal and distal limb are present in a range of species, their functional significance is unknown. We have investigated the mechanical function of the flexor cruris lateralis pars pelvica (FCLP), flexor cruris lateralis pars accessoria (FCLA) and gastrocnemius intermedia (GI), a system of linked muscles spanning proximal and distal limb segments in the guinea fowl (Numida meleagris) hind limb. The FCLP, which is in the anatomical position of a hamstring muscle, is the primary component of the linkage. It is connected to the distal femur via the FCLA, the tarsometatarsus via the tendon of insertion of the GI and the common Achilles tendon, and the tibiotarsus via a distal tendon of insertion. The FCLP may, therefore, potentially exert moments at the hip, knee and ankle joints depending on the joint angles and the relative states of activation in the three muscles. Evidence presented here suggests that the GI and FCLA act as actively controlled links that alter distal action of the FCLP. The FCLP and GI are coactive in the late swing and early stance phases of the stride, forming a triarticular complex, and likely act together to resist and control ankle flexion immediately after foot-down in addition to providing hip extension and knee flexion moments. The FCLP and FCLA are coactive from mid-through to late stance, acting together as a uniarticular hip extensor. Available evidence suggests that this role of the FCLP and FCLA is of increased importance in inclined running and accelerations. This linkage between a proximal muscle and alternate distal connections allows for functional flexibility, both in terms of the site at which the muscle exerts force and the nature of the muscle's mechanical function. The interactions generated between the proximal and distal limb by linkages of this type suggest that less emphasis should be placed on the distinct functional roles of specific anatomical classes of muscle within proximal and distal limb segments.

“…Likewise, analyses of joint rotation are usually restricted to flexion/extension (FE) angles (Sigmund, 1959;Cracraft, 1971;Rylander and Bolen, 1974;Jacobson and Hollyday, 1982;Manion, 1984;Gatesy, 1990;Gatesy, 1999;Johnston and Bekoff, 1992;Abourachid and Renous, 2000;Reilly, 2000;Verstappen et al, 2000;Ellerby and Marsh, 2010;Smith et al, 2010;Nyakatura et al, 2012). Given the relatively small transverse component of the ground reaction force during forward locomotion (Clark and Alexander, 1975;Main and Biewener, 2007;Troy et al, 2009), inverse dynamic studies normally emphasize net FE joint moments as well (Roberts, 2001;Roberts and Scales, 2004;Daley et al, 2007;Rubenson and Marsh, 2009;Andrada et al, 2013b). Our current perception of bird hind limbs thus remains deeply rooted in the erect paradigm.…”

Section: Introductionmentioning

confidence: 99%

Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

Kambic

Roberts

Gatesy

2014

104

191

Ground-dwelling birds are typically characterized as erect bipeds having hind limbs that operate parasagittally. Consequently, most previous research has emphasized flexion/extension angles and moments as calculated from a lateral perspective. Three-dimensional (3D) motion analyses have documented non-planar limb movements, but the skeletal kinematics underlying changes in foot orientation and transverse position remain unclear. In particular, long-axis rotation of the proximal limb segments is extremely difficult to measure with topical markers. Here, we present six degree of freedom skeletal kinematic data from maneuvering guineafowl acquired by markerbased XROMM (X-ray Reconstruction of Moving Morphology). Translations and rotations of the hips, knees, ankles and pelvis were derived from animated bone models using explicit joint coordinate systems. We distinguished sidesteps, sidestep yaws, crossover yaws, sidestep turns and crossover turns, but birds often performed a sequence of blended partial maneuvers. Long-axis rotation of the femur (up to 38 deg) modulated the foot's transverse position. Longaxis rotation of the tibiotarsus (up to 65 deg) also affected mediolateral positioning, but primarily served to either re-orient a swing phase foot or yaw the body about a stance phase foot. Tarsometatarsal long-axis rotation was minimal, as was hip, knee and ankle abduction/adduction. Despite having superficially hinge-like joints, birds coordinate substantial long-axis rotations of the hips and knees to execute complex 3D maneuvers while striking a diversity of non-planar poses.