Table 2 summarises the best methods for enhancingfast-twitch motor units. Conversely, the wrong training – and even what might
in some cases seem to be the ‘right’ training – can compromise their
development.
Method
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Comments
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Lifting weights in excess of 60% 1RM
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The heavier the weight, the greater the number and size of
fast-twitch motor units recruited. A weight in excess of 75% 1RM is required
to recruit the largest units
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Performing a physical activity flat-out – eg sprinting,
swimming, rowing or cycling as fast as possible
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Good recoveries are needed to maximise effort. The
short-term anaerobic energy system will positively adapt. The minimum speed
needed to contribute towards absolute speed development is 75% of maximum
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Training your muscles eccentrically
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Research indicates that this form of training increases
fast twitch motor unit recruitment.(6)
An eccentric muscular contraction generates force when muscle fibres lengthen
(see plyometric training, below)
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Plyometric training
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These exercises utilise the stretch-reflex mechanism,
allowing for much greater-than-normal force to be generated by pre-stretching
a muscle (the eccentric contraction) before it contracts. A hop, bound or
depth jump is an example of a plyometric conditioning drill; a long jump
take-off is an example of a plyometric sport skill.
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Complex training
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This can induce greater recruitment of fast-twitch motor
units by lulling the protective mechanisms of a muscle into reduced activity,
allowing it to generate greater force. Complex training involves combining
weights exercises with plyometric ones in a systematic fashion (see PP
114, Feb 1999). A good example is: 1 set of 10 squats at 75% 1RM
followed, after a 2-minute recovery, by
10 jump squats, repeated 3 times
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Over-speed training
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This will have a transferable neural effect only if the
athlete consciously moves his own limbs at the increased pace. It includes
downhill sprinting and hitting or throwing sports using lighter implements
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Good recovery
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24-48 hours’ recovery should be taken between very intense
plyometric/complex training and speed work sessions. A further 24-36 hours’
recovery will result in an over-compensatory peak – ie opportunity for a peak
performance
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Sport specific warm-up
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This will reduce the risk of injury, increase the
receptivity of the neuromuscular system to the ensuing work and reduce the
potentially contradictory effects of non-specific preparation on fast-twitch
motor units
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Mental preparation
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Maximum fast-twitch motor unit recruitment can result from
specific mental preparation before and during competition
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