Dr Mel Siff Blog

The following appeared in a newsletter by Ian King, an Australian fitness
professional who often tours the world market
(http://www.kingsports.net/bs18-askthemaster.htm)

Someone asked him in his column which he calls “Ask the Master” :

JUMP WITHOUT PLANTARFLEXION

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<In the seminar you did near Boston you mentioned during jump training, to
jump without plantar flexing the feet. What is the purpose of that? . . .
. . . >

King’s reply was as follows:

<< The technique of actually dorsi flexing in the jump has a number of
purposes, including:

* decreasing ground contact time
* therefore increasing elastic energy utilization
* teaches focus on air time, not toe time
* greater specificity with the sprint technique I teach
* reduces hamstring flex in sprint leg cycle >>

—————————-

INTRODUCTORY COMMENTS

Issues such as the following immediately spring to mind:

1. If one really wishes to jump without plantarflexion, one has to begin
from a static start way back on the heels, with no contact whatsoever between
any other part of the foot and the ground. After you have read this, try it
for yourself and experience how one needs to balance on the tip of the heel
before one even attempts this drill. Any ground contact with other parts of
the sole besides the heel will elicit a reflex tendency to plantarflex the
ankle.

2. One needs to stress that there can be dorsiflexion of the toes, as well
as the ankle. The correct phasing of contributions from each is central to
all jumping and running efficiency.

3. In referring to elastic energy utilization, it is essential to identify
in which exact tissues the elastic energy storage and release is occurring.
Regarding increased utilisation of elastic energy processes in the all of the
soft tissues involved in jumping and running, it is essential to understand
the central role played by plantarflexion.

Anyway, no scientists have yet managed to determine how much of rebounding
efficiency is due to contributions from stored elastic energy and how much is
due to facilitation of stretch and related nervous processes. To claim that
any training method will increase elastic energy usage in isolation from
other mechanisms implies that one knows the answer to a problem that science
has not yet managed to resolve.

4. Once you left the ground, air time is unaffected by anything that your
driving leg can do. Long jumpers use specific running techniques in the air
before they land, but the ability to execute them depends on a very powerful
take-off facilitated by processes including ankle and toe plantarflexion.

5. Whatever exact meaning is attributed to the obscure phrase, “reduces
hamstring flex in sprint leg cycle”, it needs to be pointed out that the
hamstrings do not “flex”. Muscles contract and relax, while joints flex or
extend. The deflection of bones under the effect of strong transverse
loading might also be regarded as a form of flexion, but “hamstring flex” is
a new one to me.

Would anyone be interested in commenting further on the validity and accuracy
of these statements, regarding either the biomechanics or the practical
issues involved?

Dr Mel C Siff
Denver, USA

For more information on Facts and Fallacies of Fitness by Dr Mel Siff please click here

Tags: Dr Mel Siff, Elastic Energy, Energy Storage, Jump Training, jumping, plantar flexion, Plantarflexion, plyometrics, powermetrics, Specificity, Supertraining