Maximal power output during cycling exercise relies on the production of maximal force
from the lower limb muscles, through their coordinated activation by the central nervous
system. Larger levels of crank power are produced during the downstroke phase of the
pedal cycle where the knee extensor muscles are highly activated and produce large levels
of joint power. Reductions in force-generating capacity of the knee extensors resulting
from fatiguing cycling exercises have been linked with a reduction in the ability of
individuals to produce crank power and alterations in muscle coordination. However,
fatigue induced by cycling exercises is likely to reduce the force-generating capacities of
the other lower limb muscles, making it impossible to identify the effect of fatigue in the
knee extensors on crank power production and muscle coordination. Isolated reductions
in force-generating capacity of the knee extensors have been observed following singlejoint
exercises requiring repeated contractions of this muscle group.
To date, it is unknown how a unilateral single joint exercise effects power production
during a bilateral movement. The aim of this study was to investigate the effect of
repeated contractions of the left knee extensor muscles on the production of crank power
and the activation of the locomotor muscles of both lower limbs during bilateral maximal
cycling exercise.