Twitchy

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.

Table 2: The best training methods for fast-twitch motor units
Method	Comments
Lifting weights in excess of 60% 1RM	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
Performing a physical activity flat-out – eg sprinting, swimming, rowing or cycling as fast as possible	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
Training your muscles eccentrically	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)
Plyometric training	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.
Complex training	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
Over-speed training	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
Good recovery	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
Sport specific warm-up	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
Mental preparation	Maximum fast-twitch motor unit recruitment can result from specific mental preparation before and during competition