Objective-To examine the effects of instructions related to joint kinematic
s, auditory stimuli, and imagery on lowering the vertical ground reaction f
orces associated with landing from a jump.
Study Design-Randomised controlled trial.
Setting-A laboratory in an educational institution.
Subjects-Eighty asymptomatic subjects (27 men) with a mean age of 24 years.
Intervention-Subjects were randomly assigned to the following groups: (1)
instruction (limb position instructions); (2) auditory cue (listen to impac
t sounds); (3) imagery (metaphorical); (4) control. Subjects were required
to jump from a box 300 mm in height and land on a force plate. Measures of
the ground reaction force were recorded before and after the intervention.
Main Outcome Measure-The peak vertical ground reaction force recorded at fo
otstrike.
Results-The peak vertical ground reaction forces in the technical instructi
on and auditory groups were significantly less than those of the control gr
oup. There was no significant difference between the auditory and technical
instruction groups. There was no significant difference between the imager
y and control groups.
Conclusions When an aim of a rehabilitation programme is to minimise forces
on the lower limb during landing type activities, the findings support the
use of instructions related to kinematics as well. as instructions that dr
aw the patient's attention to the sound at impact.