Decreasing landing forces: effect of instruction.
OBJECTIVE
To examine the effects of instructions related to joint kinematics, auditory stimuli, and imagery on lowering the vertical ground reaction forces associated with landing from a jump.


METHODS
Randomised controlled trial.


METHODS
A laboratory in an educational institution.


METHODS
Eighty asymptomatic subjects (27 men) with a mean age of 24 years.


METHODS
Subjects were randomly assigned to the following groups: (1) instruction (limb position instructions); (2) auditory cue (listen to impact 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.


METHODS
The peak vertical ground reaction force recorded at footstrike.


RESULTS
The peak vertical ground reaction forces in the technical instruction and auditory groups were significantly less than those of the control group. There was no significant difference between the auditory and technical instruction groups. There was no significant difference between the imagery 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 draw the patient's attention to the sound at impact.
McNair
P J
PJ
Neuromuscular Research Unit, School of Physiotherapy, Auckland University of Technology, New Zealand. peter.mcnair@ant.ac.nz
Prapavessis
H
H
Callender
K
K
D000328:Adult; D001696:Biomechanical Phenomena; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D019018:Imagery, Psychotherapy; D007719:Knee Joint / Q000502:physiology*; D007866:Leg / Q000502:physiology*; D008297:Male