Mel Siff

09-01-2000, 01:57 PM

Recently an article "Toward an Understanding of Power" was written in the

NSCA's Strength & Conditioning Journal (Oct 1999: 34-35), which contained

some curious biomechanical definitions and calculations. Here are a few of

them for your interest:

1. "For instance, in cleaning a weight, the velocity of the bar is equal to

its speed and the upward direction in which it moves."

2. "Strength times speed equals power"

3. Work = force x distance, where Force = Mass lifted,

Distance = gravity x height of pull

Gravity = 9.8 m per sec squared

The article then used the above definitions to calculate power and hence

compare the power generated in the Weightlifting clean and the Powerlifting

deadlift, thus:

Power = Work/Time to execute lift

...but did not distinguish at all between mean power, power at any instant

and peak power during the lifts concerned (deadlifts and cleans).

Would anyone else care to comment on the material which I have quoted above?

In a letter to the editor of the journal, I stressed that one cannot casually

equate the vector, velocity, and the scalar, speed, especially in non-linear

dynamic lifts and that work is not simply force x distance in a system in

which force and direction of application of the force is changing throughout

the movement. I also pointed out the obvious errors in equating force with

mass and in defining Distance = gravity x height of pull.

The author of the article simply replied in the Aug 2000 issue of the same

Journal that:

" I had Dr L, chairman of the math/physics department at ........ University,

review the formula along with the comments. Dr L said that my calculations

are correct...... In trying to make the formula more understandable to

people with no background in math and physics, I had added a few extra words

for clarification purposes, which to a purist was not acceptable."

Would anyone care to comment on this response, as well?

What concerns me is that this NSCA (National Strength & Conditioning

Association) publication reaches tens of thousands of its members all around

the world, many of whom do have at least 4 year degrees in physical

education, kinesiology, science, physical therapy and related fields. The

NSCA administrates and awards the CSCS (Certified Strength and Conditioning

Specialist) qualification and Personal Trainer certification. It is widely

regarded as the definitive source of strength training information for

strength coaches and includes many highly qualified scientists in its ranks,

yet it seems quite contented to allow seriously misinterpreted scientific

information to reach its members.

The NSCA is not unique in this regard. Many other certifying bodies and

training organisations in the strength and fitness realm reveal a similar

attitude that their members "are not scientists" and need not be given a

rigorous background to the simplified concepts that are taught to them.

While popularisation of difficult concepts is vital for the general public

and some folk such as the late Carl Sagan were masters at this, are these

organisations not doing their members and the strength/fitness professions a

grave disservice? Is there any solution to this problem?

Dr Mel C Siff

Denver, USA

http://www.egroups.com/group/supertraining

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NSCA's Strength & Conditioning Journal (Oct 1999: 34-35), which contained

some curious biomechanical definitions and calculations. Here are a few of

them for your interest:

1. "For instance, in cleaning a weight, the velocity of the bar is equal to

its speed and the upward direction in which it moves."

2. "Strength times speed equals power"

3. Work = force x distance, where Force = Mass lifted,

Distance = gravity x height of pull

Gravity = 9.8 m per sec squared

The article then used the above definitions to calculate power and hence

compare the power generated in the Weightlifting clean and the Powerlifting

deadlift, thus:

Power = Work/Time to execute lift

...but did not distinguish at all between mean power, power at any instant

and peak power during the lifts concerned (deadlifts and cleans).

Would anyone else care to comment on the material which I have quoted above?

In a letter to the editor of the journal, I stressed that one cannot casually

equate the vector, velocity, and the scalar, speed, especially in non-linear

dynamic lifts and that work is not simply force x distance in a system in

which force and direction of application of the force is changing throughout

the movement. I also pointed out the obvious errors in equating force with

mass and in defining Distance = gravity x height of pull.

The author of the article simply replied in the Aug 2000 issue of the same

Journal that:

" I had Dr L, chairman of the math/physics department at ........ University,

review the formula along with the comments. Dr L said that my calculations

are correct...... In trying to make the formula more understandable to

people with no background in math and physics, I had added a few extra words

for clarification purposes, which to a purist was not acceptable."

Would anyone care to comment on this response, as well?

What concerns me is that this NSCA (National Strength & Conditioning

Association) publication reaches tens of thousands of its members all around

the world, many of whom do have at least 4 year degrees in physical

education, kinesiology, science, physical therapy and related fields. The

NSCA administrates and awards the CSCS (Certified Strength and Conditioning

Specialist) qualification and Personal Trainer certification. It is widely

regarded as the definitive source of strength training information for

strength coaches and includes many highly qualified scientists in its ranks,

yet it seems quite contented to allow seriously misinterpreted scientific

information to reach its members.

The NSCA is not unique in this regard. Many other certifying bodies and

training organisations in the strength and fitness realm reveal a similar

attitude that their members "are not scientists" and need not be given a

rigorous background to the simplified concepts that are taught to them.

While popularisation of difficult concepts is vital for the general public

and some folk such as the late Carl Sagan were masters at this, are these

organisations not doing their members and the strength/fitness professions a

grave disservice? Is there any solution to this problem?

Dr Mel C Siff

Denver, USA

http://www.egroups.com/group/supertraining

---------------------------------------------------------------

To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl

For information and archives: http://isb.ri.ccf.org/biomch-l

---------------------------------------------------------------