This will be my last P&P for a few weeks, since I will be moving to the 
USA (Denver) during April 1998.  For anyone wishing to remain in contact 
with me after 20 April 1998, please use my HotMail e-mail address, as 
follows:

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I look forward to being in touch with all of you from my new land in 
the near future.
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INTRODUCTORY NOTE

For newcomers to this column, these Puzzles & Paradoxes (P&Ps) are 
Propositions, not facts or dogmatic proclamations. They are intended to 
stimulate interaction among users working in different fields, to re-examine 
traditional concepts, foster distance education, question our beliefs and suggest 
new lines of research or approaches to training.  We look forward to responses 
from anyone who has views or relevant information  on the topics.
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PUZZLE & PARADOX 115

The distinction between failure in single repetition maximum strength 
(1RM) due to inherent limitations to strength production and failure due to 
short-term fatigue may not be as clearcut as sometimes is believed.
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There has been considerable discussion regarding the role played by 
fatigue in determining hypertrophy and the number of repetitions 
which can be completed in a given exercise.  The relative proportions 
of the different types of slow and fast twitch muscle fibres have 
been implicated in these discussions, as have the energy sources for 
activities of different duration and intensity.

However, it appears that a few questions relating to an earlier P&P 
have to be posed again, namely:

Is failure in a 1RM effort in weight training  exercises due to 
intrinsic limitations within the muscle complex which maintain 
certain safety or performance barriers for a given joint action or 
exercise? - or is 1RM failure due to very short-term fatigue in the 
involved muscle groups?

If we examine the nature of strength (the subject of a topic which I 
sent out to this and other groups a few weeks ago), then we may infer 
that the inability to lift more than one's current 1RM is due to 
limitations in factors such as:

*   the total number of muscle fibres that can be activated during 
     any stage of that exercise

*  the force-producing capabilities of the cross-sectional area of the 
    relevant muscles

*  disinhibition of the Golgi-tendon organ processes during increases 
    in muscle tension towards their current maximum

*  the ability of short-term high energy phosphates to deliver 
    sufficient energy (this may well be regarded as a form of fatigue)

*  the excitation threshold of the nerve fibres supplying the relevant 
    muscles

*  the rate of contraction of the relevant muscle fibres

There are several other instrinsic factors (which Dr Verkhoshansky 
and I detail in our textbook 'Supertraining' 1996  Ch 1), but the above 
few suffice to discuss the issues raised in this P&P.

Are we justified in regarding such 'intrinsic' limiting factors as 
being entirely separate from fatigue processes or is there an element 
of certain fatigue decrements in performance operating in each of the 
above cases (and in any other factors which one may list)?

Distinction certainly is made between central fatigue and peripheral 
fatigue, where the former relates to central nervous factors ouside 
the muscle output system, whereas the latter refers to fatigue 
factors in the peripheral- and neuro-muscular systems, but is this 
adequate to allow us to distinguish between failure in a short-term
1RM event and failure in a longer duration event?

Even then, we need to distinguish between very-short term 1RM events 
such as the Olympic lift (snatch, clean & jerk) and the longer short-term 
events such as the powerlifts (squats, bench presses and deadlifts).  
The difference between these short events and the bodybuilding sets 
to failure events would appear to be a clear case of peripheral 
fatigue for bodybuilders - though, of course, central nervous events 
involving loss of motivation, impaired recruitment of spinal motor 
neurons and impaired transmission of spinal nerve impulses might also 
be involved.

Does the latter example suggest that it may be artificial to 
distinguish between 'pure' central fatigue and peripheral fatigue, 
when it may be that both classes of fatigue are involved to different 
extents in every physical activity?

If we take the whole issue down to the cellular level, fatigue may affect 
one or more of the many excitation-contraction processes which begin 
with depolarisation of the muscle cell at the neuromuscular junction, 
and end with the mechanical power output.  Disturbance at any stage 
of this chain of events will lower the capability of the muscle cell for 
realising its maximum force potential.  The primary peripheral sites 
which have been implicated in muscle cell fatigue include the motor 
end-plate, the sarcolemma, the T-tubules, the sarcoplasmic reticulum and 
contractile proteins.

Consequently, would it be preferable to regard all forms of performance 
failure as some form of fatigue, rather than as a manifestation of some or 
other intrinsic performance barriers?

Over to you.
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Dr Mel C Siff
School of Mechanical Engineering
University of the Witwatersrand
WITS 2050    South Africa
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