Post by carruthersjam on May 29, 2008 6:41:40 GMT -8
FORCE-VELOCITY, IMPULSE-MOMENTUM RELATIONSHIPS: IMPLICATIONS FOR
EFFICACY OF
> PURPOSEFULLY SLOW RESISTANCE TRAINING
>
> Brian K. Schilling, Michael J. Falvo and Loren Z.F. Chiu
> www.jssm.org/vol7/n2/16/v7n2-16abst.php
>
***
The above is an excellent paper. See excerpts:
Abstract
The purpose of this brief review is to explain the mechanical
relationship between impulse and momentum when resistance exercise is
performed in a purposefully slow manner (PS). PS is recognized by
~10s concentric and ~4-10s eccentric actions. While several papers
have reviewed the effects of PS, none has yet explained such
resistance training in the context of the impulse-momentum
relationship. A case study of normal versus PS back squats was also
performed. An 85kg man performed both normal speed (3 sec eccentric
action and maximal acceleration concentric action) and PS back squats
over a several loads. Normal speed back squats produced both greater
peak and mean propulsive forces than PS action when measured across
all loads. However, TUT was greatly increased in the PS condition,
with values fourfold greater than maximal acceleration repetitions.
The data and explanation herein point to superior forces produced by
the neuromuscular system via traditional speed training indicating a
superior modality for inducing neuromuscular adaptation.
Excerpts:
It is unlikely that a single program or method will be effective in
realizing all of the possible benefits of resistance training
equally...
Training programs have been developed that aim to regulate repetition
speed, specifically recommending purposefully slow actions (~10s for
the concentric and ~4-10s for eccentric portions). Much of the
support for such programs exists only in lay media (Brzycki, 1995;
Hutchins, 2001; Wescott, 1999), with little empirical evidence
(Greer, 2005). The arguments for prescribing such training programs
often use terminology that is not soundly based in classical physics,
or is derived from other resistance training/testing modalities
uncommon to that of question (i.e. isokinetic, in vitro or in situ
studies). For instance, protocols such as this have been confusingly
called "low force" (Hutchins, 2001) while at the same time touted as
having "more muscle tension" (Wescott et al., 2001), "more muscle
force" and "less momentum" (Wescott, 1999)....
An attempt to reduce the speed of motion subsequently reduces the
force expressed (Keogh et al., 1999)...
A potential caveat of increased TUT is that the load must be
decreased to perform a successful 10-s concentric contraction as
compared to a maximal acceleration repetition (i.e. decreased TUT)...
..Increasing TUT for an exercise session can be accomplished by
simply increasing the number of total repetitions of maximal-
acceleration exercises (increased volume-load; Tran and Docherty,
2006). This would ultimately increase the time that the muscle has
been under tension for that session, but the force output of the
muscle will have been greater due to the relatively larger loads....
CONCLUSION
The exercise professional must be aware of basic mechanical features
of all styles of resistance training in order to render an educated
prescription. While lay literature has suggested that forces are
optimal with PS, the data herein along with reviewed studies and an
examination of the impulse-momentum relationship suggests otherwise.
The inferior propulsive forces accompanying PS suggest other methods
of resistance training have the potential for superior neuromuscular
adaptation. While it is reckless to suggest one universal style of
training to all individuals, one must be careful in selecting a mode
and designing a training program in order to achieve appropriate
goals.
EFFICACY OF
> PURPOSEFULLY SLOW RESISTANCE TRAINING
>
> Brian K. Schilling, Michael J. Falvo and Loren Z.F. Chiu
> www.jssm.org/vol7/n2/16/v7n2-16abst.php
>
***
The above is an excellent paper. See excerpts:
Abstract
The purpose of this brief review is to explain the mechanical
relationship between impulse and momentum when resistance exercise is
performed in a purposefully slow manner (PS). PS is recognized by
~10s concentric and ~4-10s eccentric actions. While several papers
have reviewed the effects of PS, none has yet explained such
resistance training in the context of the impulse-momentum
relationship. A case study of normal versus PS back squats was also
performed. An 85kg man performed both normal speed (3 sec eccentric
action and maximal acceleration concentric action) and PS back squats
over a several loads. Normal speed back squats produced both greater
peak and mean propulsive forces than PS action when measured across
all loads. However, TUT was greatly increased in the PS condition,
with values fourfold greater than maximal acceleration repetitions.
The data and explanation herein point to superior forces produced by
the neuromuscular system via traditional speed training indicating a
superior modality for inducing neuromuscular adaptation.
Excerpts:
It is unlikely that a single program or method will be effective in
realizing all of the possible benefits of resistance training
equally...
Training programs have been developed that aim to regulate repetition
speed, specifically recommending purposefully slow actions (~10s for
the concentric and ~4-10s for eccentric portions). Much of the
support for such programs exists only in lay media (Brzycki, 1995;
Hutchins, 2001; Wescott, 1999), with little empirical evidence
(Greer, 2005). The arguments for prescribing such training programs
often use terminology that is not soundly based in classical physics,
or is derived from other resistance training/testing modalities
uncommon to that of question (i.e. isokinetic, in vitro or in situ
studies). For instance, protocols such as this have been confusingly
called "low force" (Hutchins, 2001) while at the same time touted as
having "more muscle tension" (Wescott et al., 2001), "more muscle
force" and "less momentum" (Wescott, 1999)....
An attempt to reduce the speed of motion subsequently reduces the
force expressed (Keogh et al., 1999)...
A potential caveat of increased TUT is that the load must be
decreased to perform a successful 10-s concentric contraction as
compared to a maximal acceleration repetition (i.e. decreased TUT)...
..Increasing TUT for an exercise session can be accomplished by
simply increasing the number of total repetitions of maximal-
acceleration exercises (increased volume-load; Tran and Docherty,
2006). This would ultimately increase the time that the muscle has
been under tension for that session, but the force output of the
muscle will have been greater due to the relatively larger loads....
CONCLUSION
The exercise professional must be aware of basic mechanical features
of all styles of resistance training in order to render an educated
prescription. While lay literature has suggested that forces are
optimal with PS, the data herein along with reviewed studies and an
examination of the impulse-momentum relationship suggests otherwise.
The inferior propulsive forces accompanying PS suggest other methods
of resistance training have the potential for superior neuromuscular
adaptation. While it is reckless to suggest one universal style of
training to all individuals, one must be careful in selecting a mode
and designing a training program in order to achieve appropriate
goals.