Muscle soreness - Pathogenesis and causes muscle soreness

Muscle functions
Muscle tissue has four characteristics:Excitability-owned to receive and respond to stimuli such as-Neurotransmitters: acetylcholine stimulate skeletal muscles to contract-Applying an electrical stimulus, electric shock cause muscle contraction-Oxytocin-hormonal stimuli cause smooth muscle contraction.Contractility, the ability to shrink.Extensibility-ability to stretch without damage.Elasticity-the ability to return to its original shape after stretching.By moving the body part in muscle contractions, blood flow and peristalsis of hollow organs such as uterus, esophagus, stomach, intestines and bladder. Muscles help maintain posture and produce heat. Muscle contractions during shivering or tremor warms the body.
Foot muscle pathophysiology
The sensation of pain in skeletal muscles is transmitted through myelinated fibers nemielinizate delta and C related. III and IV sensory neurons end in free nerve endings. Free nerve endings are distributed mainly in connective tissue between muscle fibers of arterioles and capillaries in the region and musculotendinoase junctions. Group delta myelinated fibers transmit pain quickly located. Group C fibers transmit pain diffuse slowly.The sensation of muscle soreness is related fibers run in May first group of free nerve endings of C C in muscle fibers are Polimoda and respond to a variety of stimuli, including chemical and thermal.Chemicals that trigger action potentials in group C fibers in order of effectiveness are bradykinin, serotonin, histamine and potassium.
Causes and risk factors for muscle soreness
Result from muscle strain muscle soreness from physical activity level at which they are not adapted. Any activity that produces muscle strength or stronger than normal, which is used for a prolonged period cause muscle soreness. The degree of muscle inflammation and muscle contraction depend on the duration of exercise. Intensity seems to be more important than determining the duration.
There are five hypotheses used to explain the pathophysiology of foot muscles:
1. Structural destruction by high blood pressure.This hypothesis is the most accepted theory. Pain is mediated directly by the development of tardive maximum forces and forces in the development rate of rhythmic contractions. Muscle soreness is not mediated by muscle fatigue. Rhythmic and tetanic contractions that cause fatigue and discomfort most powerful muscle during exercise leading to pain after exercise. Structural destruction is evident in the muscles that are not qualified for that activity.
2. Accumulation of metabolic product.One of the most popular concepts is the accumulation of lactic acid in muscles. Degeneration and regeneration of muscle fibers observed after 2-3 hours of ischemia are quantitatively and temporally similar to the forces that result from exercise-induced injury. There is a relationship between exercise intensity and extension of inflammation. Exercise that involves eccentric contractions require less oxygen consumption and produce less milk compared to exercise with concentric contractions.
3. High temperature.Free nerve endings of type C and delta are sensitive to temperature 38-48 C. The high temperature can destroy the structural elements of muscle with muscle necrosis and tissue collapse. Eccentric exercise can generate local temperatures higher than concentric contractions. Rhabdomyolysis-muscle soreness is far more prevalent in untrained individuals during exercise performed in the heat.
4. Spastic contractures.Some studies show increased electromyographic activity in inflamed muscles. The loss of nervous control and vasoconstriction leading to decreased blood flow and ischemia, which in turn initiates a pain-spasm cycle. The magnitude of pain depends on the number of motor units involved.
5. Remodeling miofibrilara.The literature suggests that alterations miofibrilare and foot muscle cytoskeleton are trademarks of miofibrilelor reflcta adaptive remodeling.
There are four types of changes in muscle soreness:Z-expansion amorphous areasSarcomere-wideningDouble Z-zonesSupernumerary-sarcomere.
Exercise that involves eccentric contractions lead to rupture or damage of the strong over the concentric muscle. Therefore any form of exercise with eccentric muscle contractions cause muscle soreness. To produce a muscle force on motor units are activated at a less eccentric compared to a concentric contraction. In eccentric contraction force is spread over an area of ​​small sections of muscle. Sequential expansion drive regional tension fracture mechanics to determine the structural elements of muscle fibers or connective tissue that is in series with contractile elements.