Limb anatomy influences swing duration and angular velocity: Implications for understanding primate locomotor adaptations

Daniel Schmitt, Pierre Lemelin, Charlotte E Miller

Research output: Contribution to conferenceConference Abstractpeer-review

Abstract

To understand the functional correlates ofdiversity in limb length, mass, and weightdistribution among mammals, mostbiomechanical studies have focused on stancephase mechanics, while swing phase hasremained relatively understudied. Previousstudies have shown that as animals move fasterthe stance period shortens while the swing periodstays relatively constant. This suggests thatmechanical qualities, such as limb length andmass distribution, constrain swing timing andcan influence animal velocity and energeticcosts. Primates–with relatively more distalweight distribution associated with prehensilehands and feet–may experience longer swingperiods compared to other mammals. We testedthis hypothesis by calculating swing period fromvideorecords for a wide range of mammals,including humans, dogs, cats, kinkajous, coatis,lemurs, squirrel monkeys and callitrichids. Inevery species in our sample stance durationdecreases with increasing speed and swingduration remains nearly constant. When absoluteswing durations are compared, most species wereidentical, although dogs and marmosets showedsignificantly shorter absolute swing durationsthan other mammals. This similarity in swingperiod (in spite of differences in limb length)leads to differences in angular velocity, and thus,muscular effort needed to accelerate anddecelerate the limb. Although relatively longerlimbs and grasping cheiridia may providebenefits for increasing stride length and stability,such anatomy may also constrain speed,influence speeds at which gait transitions occur,and increase costs of locomotion. Understandingthe relative costs and benefits of different limbanatomies allows a better understanding ofselective pressures driving morphologicalevolution in primates.
Original languageEnglish
Publication statusPublished - 11 Apr 2014

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