Exhaustion

The state of exhaustion is one that is a common occurrence in all forms of athletic performance. It is a description that is intended to reflect a final, often dramatic, result of one or more bodily processes on the brink of failure. Where there is exhaustion, there must be an extreme level of fatigue, to the point where relief must be sought by the athlete or a catastrophe will invariably follow.

Exhaustion is a term employed in three distinct contexts in sports science. Physical exhaustion is the expression used to describe either musculoskeletal fatigue or a general inability to physically continue to perform at the desired level due to all energy stores having been consumed. Physical exhaustion is most common in those sports where the activity occurs over a longer period of time, as in distance events of all types; it may also arise through prolonged training for shorter duration events. Mental exhaustion is the loss of mental keenness. Mental fatigue can occur during an event, such as an endurance race, but more commonly this state occurs in a cumulative fashion, due to factors such as the pressure of high level competition or the stress imposed upon the athlete through daily training sessions. Terms such as "burnout," "staleness," and "brain-fag" are expressions of mental exhaustion. Heat exhaustion is a subset of physical exhaustion, but as it arises in specific environmental circumstances, it has a separate and well-developed set of physical indicators.

Reggie Evans of the Seattle Supersonics flops on the ground in exhaustion during a game.

Physical exhaustion is a condition that is most commonly revealed by extreme fatigue on the part of athletes, where they are no longer physically capable of performing at their accustomed level. As physical exhaustion typically occurs in endurance sports, it is the aerobic energy system that is central to an examination of the mechanics of this condition. When the body requires energy for activities lasting longer than approximately 90 seconds, it will fuel itself through the production of the energy source adenosine triphosphate (ATP), using available stores of glucose. ATP is produced as the culmination of a process whereby the bodily carbohydrate stores, glycogen, are converted to glucose and transported through the red blood cells of the bloodstream to the muscles where the ATP conversion occurs. The red blood cells also transport the oxygen required to metabolize, or burn, this fuel; the blood also removes the waste products and carbon dioxide produced in this process.

The simplest and most common form of physical fatigue is when the body simply runs out of the primary sources of carbohydrate required to manufacture energy in the form of ATP. When the body determines that it has no more glycogen available to it (the liver regulates the level of these sugars present in the bloodstream), it will revert to the consumption of stored fats to convert into energy sources. Fats are a comparatively lesser, more inefficient fuel for energy production. As with any machine, when the fuel sources are spent, the body cannot continue to perform. An inability to produce energy does not only affect the muscles and other working components of the body, but also the functioning of the brain and the central nervous system; a depletion of physical energy stores will cause significant reductions in concentration and mental function.

Absent any other physical factors contributing to the physical exhaustion, such as extreme cold or altitude, this circumstance will be corrected through rest and the ingestion of appropriate carbohydrate-rich foods to redress the bodily balance. The other most common potential causes of physical exhaustion in an athlete, occurring either singly or in combination with other factors, include: illness (such as cancer); poor long-term nutritional habits (such as lacking vitamins or minerals necessary to the function of the energy systems); mental stress; environmental condition (e.g., air pollution); and dehydration (when the fluid level of the body is reduced, the volume of fluid in the bloodstream is correspondingly less).

Physical exhaustion is also an expression used to describe the testing processes used to calculate performance measures such as VO₂max, the maximum amount of oxygen that an athlete can process, which is a powerful indicator of endurance sport fitness. Physical exhaustion is also the stated limit to carbohydrate depletion tests and interval training of all types. The immediate, short-term athletic goal in each of these mechanisms is to train to physical exhaustion; the long-term objective is to extend the prior physical limits.

Mental exhaustion can arise in a number of circumstances in relation to both training and competitive circumstances. Professional team sport athletes who are required to play a number of games over a period of weeks will often complain of a lethargy and lack of motivation. Hard training, especially when the individual components are repetitive, can occasionally result in a similar mental fatigue.

Heat exhaustion a progression in the overheating of the body known as hyperthermia. When the body is working, especially in warm or humid conditions, it cools itself by forcing warm blood to the surface of the skin, which results in the production of perspiration, which in turn both dehydrates the system and depletes the body of the mineral sodium. The symptoms of heat exhaustion are severe thirst, generalized weakness, and a loss of coordination (due to reduced mineral levels, which aid in the transmission of nerve impulses to the muscles). The next stage in this progressive heat illness is a heat stroke, which may result in cardiac arrest and death. A notable fatality due to heat stroke was that of Korey Stringer, National Football League (NFL) lineman, in 2001 during a hot weather training camp session.

http://www.faqs.org/sports-science/Dr-Fo/Exhaustion.html

Ankle Anatomy and Physiology

The human ankle is the joint created at the point where the tibia (the shin bone) and the fibula (the outer bone running from the knee to the ankle) meet the talus (the ankle bone). Running parallel to the tibia and fibula, behind the ankle, is the Achilles tendon. The talus is positioned above the calcaneus (heel bone). The joint created where these three bones meet is known as the synovial joint, a joint where the component parts function due to the presence of a viscous, fluid lubrication between the bones. The ankle is a structure where its function is a compromise between the greater flexibility and range of motion as found in joints such as the shoulder, and the less flexible and more limited range of motion found in the very stable joints, such as the pelvis.

The human ankle has a deceptively simple construction; understanding its strengths and its limitations is a critical component to efficient, stable human movement and athletic success.

The epiphysis, which is the surface of the ends of the tibia and fibula where the ankle is joined, are lined with a smooth cartilage that is 0.07-0.11 in (2-3 mm) thick. The bones and cartilage are contained within the synovial membrane cavity, the space surrounding the tibia, fibula, and talus, which creates a friction-reduced surface in the joint. The ankle is provided further support through the bursa, which are sealed fluid sacs positioned between the bones of the ankle. The propulsion necessary to walk, run, or jump is achieved in a combination of movements coordinated between the flexors located on the top of the foot, and the ligaments of the ankle, which connect the ankle bones. The ligaments, which have a somewhat elastic construction, radiate from the talus to each of the calcaneus, tibia, and fibula.

The ankle is required to bear forces of 1.5 times the body weight through walking; running, or jumping forces will exceed 3-4 times body weight. When additional twisting forces, referred to as torque, are generated through sport performance and are added to the regular weight-bearing stresses, the risk of ankle injury is pronounced. The majority of injuries involving the ankle and its related structures are sprains, a relatively straightforward and treatable condition; it is where the injury is either treated incorrectly, or where the athlete returns to training or competition too quickly, that the uncomplicated injury can escalate into a chronic problem.

Everyone has a natural foot strike: the manner in which the foot comes into contact with the walking or running surface. For over 80% of athletes, the natural motion is "pronation," in which the foot turns inwardly upon contact with the running surface; the less common "supination" is when the foot rolls outward. The manner and the degree to which the foot strikes the surface place pressure on the ankle.

The natural foot strike is mimicked in the mechanisms of the ankle sprain, referred to as inversion and eversion, which are circumstances created when the ankle becomes unstable. Inversion is the common result when an athlete seeks to change direction, or "cut" on the playing surface, and the ankle joint moves inwards as the forces are applied. Eversion utwards on movement being made. Both mechanisms result in the ligaments becoming strained. Inversion may also result when a player jumps or strides and lands on an unequal surface, such as another player's foot or a hole in the playing field. In a more serious circumstance, the ankle ligaments may become torn, requiring medical intervention.

A high ankle sprain is a condition usually caused by a force being applied to the leg above the ankle, causing a degree of rotation to occur in the lower leg above the ankle joint, while the foot remains planted to the surface. In this circumstance, the tibia and fibula become separated from where these bones meet the talus, causing the ligament that connects these bones to the talus to become strained.

The ankle may also be injured through damage to the Achilles tendon, either through irritation of the tendon fibers and sheath, referred to as Achilles tendonitis, or through a tear or rupture of the tendon fibers. These injuries are typically caused by either overuse, such as dramatically increased training levels in a short period, or through a sudden explosive motion that is not properly supported due to tight calf or quadriceps muscles.

Any of the bones that comprise the ankle joint may become fractured through a direct blow. In sports such as field hockey or soccer, the ankle is exposed to such traumas. In addition, the ankle can become dislocated, where the tibia/fibula and talus are forcibly separated. Further, the tibia or the fibula may sustain damage known as shin splints, a micro tear of thin muscle covering the shins, through overuse or poor fitting footwear.

The ankle is a joint that can be significantly protected from injury through a commitment to a specialized stretching program. In addition, many sports require athletes to either wear a brace (volleyball is a sport in which braces are a part of the competitive culture), or to tape the ankles in advance of training or competition.

The basic components of good ankle care include warm-up and cool-down practices involving ankle and lower leg stretches; stretching exercises (as a part of the over all fitness program); careful attention to the heel wear and the support in athletic shoes; and shoe fit, as an improper fit may cause the foot to strike the surface and cause inversion/eversion.

http://www.faqs.org/sports-science/A-Ba-and-timeline/Ankle-Anatomy-and-Physiology.html

Lower Leg Anatomy

The lower leg is a remarkable structure, where each of its sophisticated components must work in harmony with the adjacent mechanisms to achieve support for the body or movement. No portion of the lower leg anatomy is capable of independent physical action.

The lower leg anatomy is composed of five distinct parts: the knee joint, the shin, the calf, the ankle, and the foot. In terms of the general functions of the lower leg, all movement is initiated by either a flexion or an extension of the knee joint. Either movement will stimulate a corresponding action on the part of the calf muscles and the attached Achilles tendon. These structures are themselves attached to the flexor and extension muscles of the ankle and the foot, which govern how the foot will be moved. The entire process of knee action to foot position is not a continuum, progressing down the lower leg. It is an integrated, system-wide response to a stimulus transmitted by the brain to the central nervous system and simultaneously received at the nerve endings in the muscles of the lower leg.

When the lower leg components respond in harmony to the direction of the nervous system to achieve the desired physical movement, all components must be functioning properly. When one of the lower leg anatomical parts is not capable of a proper response, the entire structure is compromised.

The knee joint is the hinge mechanism that initiates the propulsion of the lower leg. A flex of the hinge, powered by the hamstring and quadriceps

When one of the lower leg anatomical parts is not capable of a proper response, the entire structure is compromised.

muscles of the upper leg, will bring the other parts of the lower leg upward. The skeletal components of the knee joint are the protective patella, or kneecap, the femur, or thigh bone, connected at the joint to the tibia, the shin bone, and the fibula, which are the long bones of the lower leg. The integrity of the knee joint is secured by the sets of ligaments connecting the three bones, as well as through the stabilizing effect of knee cartilage.

The tibia and the fibula are commonly treated as a single skeletal structure. While neither bone is capable of independent movement, the chief function of these bones is in the formation of the knee and the various ankle joints, as well as providing support over a significant anatomical distance the tibia (the shin bone), relative to the overall body height, can range in length from approximately 10 in to over 20 in (25-50 cm) in healthy adults. The shin is covered with a very thin tissue that represents the limited cushion between the surface of the tibia and the skin. The most common ailment involving the shin is medial tibial stress syndrome, or shin splints, caused by the stresses of either poor running mechanics or overuse directed into the tissue adjacent to the tibia.

The tibia and the fibula provide support for both the calf muscles and the Achilles tendon. The calf muscles are a two-part structure, the larger gastrocnemius and the underlying soleus muscle. These are connected to the knee joint at one end, and through the Achilles tendon are joined to the calcaneus, the heel bone. The calf muscles and the Achilles working in concert link the flexing and extending motions of the knee to the movements of the ankle and the foot.

The ankle joint is created at the junction of the tibia, fibula, and the talus, the ankle bone. There are three separate joints formed by these three bones, all of which are secured by a protective structure known as the synovial capsule, which encloses the joint in a fluid that both protects and lubricates the joint. The three bones are connected by way of three separate sets of ankle ligaments. The structure of the joint and the manner in which its ligaments are arranged permits the ankle to be rotated, flexed, and extended in all directions.

The ankle is attached to the bones of the foot at the talus, which is positioned above the calcaneus, the largest of the bones of the foot. It is the heel that absorbs a significant degree of force in every movement made through the lower leg. The ankle and the foot skeleton are comprised of 26 different bones, many of which are small, but are secured through the sophisticated structure of the foot anatomy. In addition to its bone structure, the arch of the foot is secured through the plantar, which extends from the heel to the forefoot, often referred to as the ball of the foot. The metatarsal bones are the five structures extending from the ankle to the toes, or phalanges, which extend from the base of the metatarsalphalangeal joint. Each toe is secured by its own set of ligaments; movement of the toes in relation to the rest of the structure of the foot is achieved through a complex system of tendons and small muscles on the top, the sole, and the sides of each foot.

http://www.faqs.org/sports-science/Je-Mo/Lower-Leg-Anatomy.html