Muscle Soreness and Dynamic Muscle Flexibility

Muscular overexertion may present as muscle soreness, muscle stiffness, and muscle spasm. According to the muscle spasm hypothesis of muscle soreness, ischemia to the muscles release pain substances from the muscle fibers and stimulate the pain receptors, resulting in reflex spastic contractions and a continued cycle of ischemia and pain, Stretching the muscles helps reduce the spasms and associated pain. According it) the tissue damage hypothesis, micro-tears occur and pain/soreness results from the nerve - endings being stimulated by muscle tissue swelling. Proper massage aid in reducing tissue edema, and decreasing accompanying muscle spasm. Ice applications or other forms of cryotherapy, and pool training, may facilitate the body's healing response. Appropriate rest will allow microscopic damage of the tissue to heal.

Active range of motion, also called dynamic flexibility, refers to the degree to which a joint can be moved by a muscle contraction, usually through the mid-range of movement. Dynamic flexibility is not necessarily a good indicator of the stiffness or looseness of a joint because it applies to the ability to move a joint efficiently, with little resistance to motion.

Passive range of motion, sometimes called static flexibility, refers to the degree to which a joint may be passively moved to the endpoints in the range of motion. No muscle contraction is involved to move a joint through a passive range.

When a muscle actively contracts, it produces a joint movement through a specific range of motion. However, if passive pressure is applied to an extremity, it is capable of moving farther in the range of motion. It is essential in sport activities that an extremity is capable of moving through a non-restricted range of motion. For example, a hurdler who cannot fully extend the knee joint in a normal stride is at considerable disadvantage because stride length and thus speed will be reduced significantly.

Passive range of motion is important for injury prevention. There are many situations in sport in which a muscle is forced to stretch beyond its normal active limits. If the muscle does not have enough elasticity to compensate for this additional stretch, it is likely that the musculotendinous unit will be injured.

ATP -The Immediate Energy Source

Various sports activities involve specific demands for energy. For example, sprinting and jumping are high - energy activities, requiring a relatively large production of energy for a short time. Long - distance running and swimming, on the other hand, are mostly low - energy activities per unit of time, requiring energy production for a prolonged time. Other physical activities demand a blend of both high - and low - energy output. These various energy demands can be met by the different processes in which energy can be supplied to the skeletal muscles.

Energy is produced from the breakdown of nutrient foodstuffs?' This energy is used to produce adenosine triphosphate (ATP), which is the ultimate usable form of energy for muscular activity. Adenosine triphosphate is produced in the muscle tissue from blood glucose or glycogen. Glucose is derived from the breakdown of dietary carbohydrates. Glucose not needed immediately is stored as glycogen in the resting muscle and liver. Stored glycogen in the liver can later be converted back to glucose and transferred to the blood to meet the body’s energy needs. Fats and proteins can also be metabolized to generate ATP.

Once much of the muscle and liver glycogen is depleted, the body relies more heavily on fats stored in adipose tissue to meet its energy needs. The longer die duration of an activity, the greater the amount of fat that is used, especially during the later stages of endurance events. During rest and sub maximal exertion, both fat and carbohydrates are used as energy substrate in approximately a 60% to 40% ratio.

Regardless of the nutrient source that produces ATP, it is always available in the cell as an immediate energy source. When all available sources of ATP are depleted, more must be regenerated for muscular contraction to continue.

Fatigue during Muscular Exercise

Muscular fatigue is usually defined as the inability to maintain a given exercise intensity. As we will see, there is no one cause of fatigue. Fatigue is task - specific and its causes are multifocal and vary from occasion to occasion. Fatigue during muscular exercise is often due to impairment within the active muscles themselves, in which case the fatigue is peripheral to the CNS and is due to muscle fatigue. Muscular fatigue can also be due to more diffuse, or more central, factors. For example, for psychological reasons an athlete may be unable to bring his or her full muscle power to bear in performing an activity. Alternatively, environmental factors such as hot, humid conditions may precipitate a whole series of physiological responses that detract from performance. In such cases, the cause of the fatigue resides outside the muscles.

Not only does the cause of fatigue vary with the nature of the activity, but the training and physiological status of the individual, as well as environmental conditions, affect the progress of fatigue during exercise. Fatigue can be due specifically to depletion of key metabolites in muscle or to the accumulation of other metabolites, which can affect the intracellular environment and also spill out into the circulation and affect the general homeostasis. The failure of one enzyme system, cell, or muscle group is likely to affect numerous other cells, organs, and tissues. Therefore, the causes of fatigue are interactive.

The study of fatigue in exercise has occupied the attention of many of the best biological scientists. Identifying a cause of fatigue is not simple, as it is often difficult to separate causality from concurrent appearance.