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Muscle Training

All muscle training falls into three categories:

  • Isotonic Training
  • Isometric Training
  • Isokinetic Training

Isotonic

In isotonic contractions, the muscle contracts and shortens, giving movement. Nearly all the training you do is isotonic.

Advantages

  • Strengthens a muscle throughout the range of movement
  • You can choose isotonic exercises to match the actions in your sport

Disadvantages

  • Can make muscles sore, because of stress while they shorten
  • The muscle gains most strength at the weakest point of the action, rather than evenly throughout

Isometric

In isometric contractions, the muscle contracts but does not shorten, giving no movement. The Plank is a good example of an isometric contraction.

Advantages

  • Isometric exercises develop static strength - the strength you need to push or pull a heavy object or hold it up
  • They are quick to do and don't hurt
  • They do not need expensive equipment
  • You can do them anywhere

Disadvantages

  • The muscle gains strength only at the angle you use in the exercise
  • During an exercise, the blood flow to the muscle stops, blood pressure rises, and less blood flows back to the heart. It could be dangerous if you have heart problems

Isometric training is not sufficient on its own. You need to combine it with isotonic training.

Isokinetic

In isokinetic contractions, the muscle contracts and shortens at constant speed. An isotonic contraction is different to an isokinetic contraction because it is usually slowest at the start.

For isokinetic training, you need special equipment that detects when a muscle is speeding up, and increases the load to slow it down again.

Advantages

  • The muscle gains strength evenly all through the range of movement
  • It is the fastest way to increase muscle strength

Disadvantage

  • The equipment is very expensive so most gyms cannot afford it

Concentric & Eccentric Contraction

Concentric contraction occurs when a muscle shortens in length and develops tension e.g. the upward movement of a dumbbell in a biceps curl or as you spring back from a jump landing, extending your knees and jumping back up in the air, the quadriceps are shortening as they create force to push you off.

Eccentric contraction involves the development of tension whilst the muscle is being lengthened e.g. the downward movement of a dumbbell in a biceps curl or when you land on two feet from a jump and bend your knees the quadriceps are lengthening.

Eccentric movements recruit most fast twitch fibres

Research, McHugh et al. (2002)[1], investigated the difference in activation patterns between eccentric and concentric quadriceps contractions. The researchers measured the amount of muscle activity as revealed by electromyography (EMG) and the mean frequency of the EMG signal. As a rule, the larger the EMG signal recorded the more muscle fibres are being recruited, while the frequency of the signal is an indication of how fast they are being recruited. Research has shown that higher frequency EMG is consistent with greater fast twitch fibre recruitment.

They found that the total EMG signal was greater during the concentric phase, suggesting more muscle fibres are active at this time, while the mean frequency of the EMG signal was greater during the eccentric phase, suggesting more fast twitch fibres are being recruited at this time. They concluded that during a maximal eccentric contraction there is less total muscle fibre recruitment, with fast twitch fibres recruited in preference to slow twitch ones, whereas during a maximal concentric contraction all the muscles fibres are used.

This finding is significant for power athletes as the research suggests that if you want to train your fast twitch fibres it would seem that eccentric contraction movements are more useful than concentric ones. Plyometric exercises, which involve high-force eccentric movements, would be particularly useful for this purpose. A good example is the depth jump, which involves jumping off a box, bending at the knee and hip to control the landing softly, then jumping back up. Power athletes may also want to consider performing strength exercises using the eccentric phase only. By this means you may be able to target just the fast twitch fibres and perform less total work, potentially making the training more efficient. You will need a training partner or coach to assist you with each concentric phase, leaving you to complete the effort on each eccentric phase alone.

Delayed Onset of Muscle Soreness (DOMS)

Muscle soreness that occurs some 24 to 48 hours after intense exercise usually involves eccentric contractions. This causes increases in intracellular pressure that irritates the nerve endings, producing swelling and local pain. The soreness can be an indication of potential muscle adaptation to follow, but if it persists or is debilitating then it could indicate over training or large muscular tissue damage.

An appropriate warm up and cool down may help to avoid or reduce DOMS.

Referenced Material

  1. McHUGH, M. P. et al. (2002) Differences in activation patterns between eccentric and concentric quadriceps contractions. Journal of Sports Sciences, 20 (2), p. 83-91

Associated References

The following references provide additional information on this topic:

  • PIPES T. V., & WILMORE, J. H. (1974) Isokinetic vs isotonic strength training in adult men. Medicine and science in sports7 (4), p. 262-274
  • KANEHISA, H., & MIYASHITA, M. (1983) Effect of isometric and isokinetic muscle training on static strength and dynamic power. European journal of applied physiology and occupational physiology50 (3), p. 365-371
  • KOVALESKI, J. E. et al. (1995) Isotonic preload versus isokinetic knee extension resistance training. Medicine and science in sports and exercise27 (6), p. 895-899

Page Reference

The reference for this page is:

  • MACKENZIE, B. (2000) Muscle Training [WWW] Available from: http://www.brianmac.co.uk/mustrain.htm [Accessed

Associated Pages

The following Sports Coach pages should be read in conjunction with this page: