Hindlimb interarticular coordinations in Microcebus murinus in maximal leaping.

The purpose of this study was to investigate the pattern of coordinations of the hindlimb joints in the world's smallest living primate (Microcebus murinus). The sequencing and timing of joint rotations have been analyzed in five adult males performing maximal leaping from a take-off immobile platform to their own wooden nest. Angular kinematics of hip, knee, angle and metatarso-phalangeal (MT) joints were deduced from high-speed X-ray films in the sagittal plane of the animals. The body mass center (BMC) of the lemurs was assimilated to their iliac crest. The maximal airborne performance of the lemurs was 0.33 +/- 0.04. m, which represented 2.55 +/- 0.36 times their snout-vent length. Take-off instant occurred 72 +/- 7 ms after the start of the push-off, with a BMC velocity of 3.23 +/- 0.48 m s(-1), oriented 55 +/- 14 deg. with the horizontal plane. The kinematic analysis of the joints and musculotendon architecture of the M. murinus plantar flexors pointed out mechanical power amplifier mechanisms (i.e. stretch-shortening cycle of hindlimb muscles and proximo-to-distal sequence).