Group fitness instructors frequently are warned that stepping forwards off an
aerobics step is dangerous for the lower extremity, but are sometimes very
confused by the dearth of evidence supporting this "rule". Does such
scientific evidence exist or is this commandment yet another of the numerous
fitness myths that bedevil the paths of every fitness instructor and
therapist?
To answer this question, we need to ponder the following relevant puzzles
regarding this issue.
If stepping down off steps is potentially dangerous, does this imply that we
should, wherever possible, avoid descending long flights of stairs in our
normal daily lives?
In addition, in Martial Arts and Tae Bo, many of the movements involve
suddenly terminated powerful front stepping movements and lunges that can
place far greater stress on the knee than stepping off a small aerobics step.
The same sort of event happens in any sport where you transfer your weight
forwards or downwards, then suddenly stop or change direction. Many high
repetitions of this type of rapidly terminated stepping occur in ball sports
such as tennis, racquetball, badminton, soccer, football, baseball,
basketball and table tennis, and even in activities such as Latin American
dance. Does this mean that all of these activities should also be regarded
as potentially dangerous for the knees?
Interestingly, force plate measurements show that stepping backwards off
aerobics steps often produces just as much force as forward stepping, so why
is stepping back and down also not condemned?
The implications of any generalised blanket ruling for front downward
stepping are so vast that they warrant careful re-examination. Careful
consideration of issues such as those raised above can help us come to a less
dogmatic and more scientifically valid understanding of the use of any
stepping actions in different situations.
For a start, we have to remember the basic principle that it is not
necessarily an activity that may be dangerous, but the manner in which it is
executed.
Mel Siff
Dr Mel C Siff
Denver, USA
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