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MUSCLES AND INJURY .

MUSCLES AND INJURY . David L Morgan plus Paul Percival, Sumit Parikh, Gita Pendharkar, Jodi Richardson and others. Eccentric exercise is:. Using muscles as brakes, Active muscles trying to shorten but being forcibly extended. Load exceeding isometric capability.

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MUSCLES AND INJURY .

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  1. MUSCLES AND INJURY. David L Morgan plus Paul Percival, Sumit Parikh, Gita Pendharkar, Jodi Richardson and others

  2. Eccentric exercise is: • Using muscles as brakes, • Active muscles trying to shorten but being forcibly extended. • Load exceeding isometric capability. • Absorbing energy, not delivering it. • An important function of muscle. • Present is some sports but not others.

  3. Eccentric exercise produces: • Delayed Onset Muscle Soreness, • Other physiological changes. • Adaptation, ie less soreness next time. • Gross muscle tear in some cases.

  4. Mechanism. • Muscles generate tension by forming bonds between overlapping arrays of filaments. • Muscle active tension decreases at long length. • A series connection of such sarcomeres is “unstable”.

  5. Hypothesis I: Stretching of active muscle at high speeds and at lengths beyond optimum does not involve uniform lengthening of sarcomeres, but more closely resembles “popping” of sarcomeres, one at a time, in order from weakest to strongest. This leads to damage.

  6. Hypothesis II: Adaptation. • Muscle grows more sarcomeres in series. • This causes a greater optimum length. • More sarcomeres for the same muscle length leads to shorter sarcomeres, avoids extension beyond optimum length, avoids non-uniformities and so damage. • Down side is increased energy to generate force.

  7. Hypothesis III: Injury. • Muscle tear starts at weak point caused by non-uniformity. • Hence training to prevent DOMS will also prevent injury. • Successful training will be seen by a longer optimum.

  8. Injury Projects. • Testing footballers on Biodex to find optimum. Measure previously injured. Test effect of training • Devise optimum training exercises. • Measure activity with accelerometers in a shin guard.

  9. Toe walker Projects. • Toe walkers walk with heels off the ground • Muscles grow short. • Can eccentric exercises make calf muscles grow longer? • Equipment to monitor both toe-walking and exercise.

  10. Heel strike Toe walking Horizontal Vertical

  11. Stimulation Project. • Electrical stimulation of paraplegic muscle requires high rate to get smooth contraction. • This causes fatigue. • Can optimised distributed stimulation help? • Working with NeoPraxis, an arm of Cochlear.

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