This paper presents biomechanical and pathophysiologic
data on muscle tears in two simulated physiologic states:
&dquo;warm&dquo; and &dquo;cold.&dquo; Our results show that a greater force
and increase in length are needed to tear isometrically
preconditioned (warmed) muscle. The MTJ was the site of
failure in all of the muscles and the physiologic state did not
alter the site of failure. The unconditioned (cold) muscles
appear more inelastic at each increase in length. This study
provides a biomechanical explanation of the mechanisms by
which warmup may reduce the incidence of musculotendinous
injury. An increased understanding of the benefits of
muscle warmup is of great importance to athletes, sports
medicine physicians, and orthopaedic surgeons in general.