Enzyme Levels
We can also assess muscle damage by the presence of proteins in the bloodstream, which remain within the muscle under normal circumstances. CK is the enzyme most commonly associated with EIMD, although Mb and other enzymes are also present. CK usually remains inside muscle fibres for ATP conversion, but can leak into the bloodstream after extreme exercise and injury to myofibrils. This is due to the disruption of the cell membrane. A peak in concentration is shown after 5 days and remains elevated for several days afterwards.
This shows us that the immediate muscle damage causes a number of further events, including a loss of intracellular components. Although CK levels can provide a gross indication of muscle damage, it is not a precise indicator of injury magnitude.
This shows us that the immediate muscle damage causes a number of further events, including a loss of intracellular components. Although CK levels can provide a gross indication of muscle damage, it is not a precise indicator of injury magnitude.
Range of Motion, Torque & Susceptibility to Muscle Damage
Muscle stiffness is increased by muscle damage, causing an immediate decrease in range of motion (ROM) after exercise. Some studies have shown a peak decrease in ROM 3 days after exercise; with a minor decrease still evident 7 days post exercise. This timing correlates closely with a peak in swelling of the damaged muscles.
Muscle function is perceived as the best way of assessing severity of muscle damage. Whilst concentric maximal voluntary contraction (MVC) levels return to normal at 2 hours post-exercise; MVC sometimes still doesn't return to normal levels even after 7 days following extensive eccentric work. MVC decrease has been shown to have a high correlation with myofibrillar damage.
As would be expected, the amount of muscle damage relies heavily on intensity, speed and number of contractions. However, it is thought that type II muscle fibres may be more susceptible to damage because of they are favourably recruited in eccentric exercise. This being said, the biggest contributing factor is exercise history, meaning that sensible programming is essential if you wish to minimise EIMD.
Muscle function is perceived as the best way of assessing severity of muscle damage. Whilst concentric maximal voluntary contraction (MVC) levels return to normal at 2 hours post-exercise; MVC sometimes still doesn't return to normal levels even after 7 days following extensive eccentric work. MVC decrease has been shown to have a high correlation with myofibrillar damage.
As would be expected, the amount of muscle damage relies heavily on intensity, speed and number of contractions. However, it is thought that type II muscle fibres may be more susceptible to damage because of they are favourably recruited in eccentric exercise. This being said, the biggest contributing factor is exercise history, meaning that sensible programming is essential if you wish to minimise EIMD.