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iceberg profile in sport psychology, a proposed ideal profile of moodstate for elite performers, characterized by low scores on negative moods (specifically tension, depression, anger, fatigue and confusion) and high scores on positive moods (specifically vigour). Known as ‘iceberg’ because, according to this proposition, when elite performers’ moodstate scores are standardized and plotted they should show an iceberg-shaped profile with negative mood scores lying below the mean and the vigour score lying above the mean.
ideal self a person’s conception of how they would ideally like to be.
idiographic relating to the study of individuals rather than groups. See also nomothetic.
iliotibial band a band of connective tissue, continuous above with the tensor fasciae latae muscle which is attached to the iliac crest, and extending down to be inserted on the outer side of the tibia below the knee. iliotibial band syndrome is one of the commonest causes of knee pain in runners, with pain localized to the insertion on the lateral aspect of the tibia where the band rubs on the lateral tibial condyle. Classically caused by road running, especially on cambered surfaces, associated with excessive pronation. The key to treatment is to identify the cause and improve the flexibility and strength of the band.
imagery the process of forming symbolic mental representations of objects, events or actions, which may be in any of the sensory modes. In sport psychology the effective and deliberate use of imagery is considered to be one of the fundamental mental skills for sports performers and is used for mental rehearsal, motivation, relaxation and stress management. external imagery is that engaged in from a third person perspective as if an external observer were watching the person doing the imaging; internal imagery is that engaged in from the first-person perspective of the person doing the imaging. In kinaesthetic imagery the person images bodily movements or sensations. In visual imagery the person creates a mental picture of an object, event or action, also known as visualization. See also psychoneuromuscular theory.
immune system the body’s protective measures against threats of damage or disease from invading antigens (micro-organisms, foreign proteins, implants or grafts) or in pathological conditions from ‘self antigens’ (malignant cells, healthy or damaged tissue). antibodies (immunoglobulins) are produced, each specific against a particular antigen, and circulate in the blood plasma and tissue fluids. The immune response involves interaction of antigen and antibody. See also allergy, anaphylaxis, immunity, lymphatic system.
immunity the protected condition provided by the immune system or by medical interventions. natural (innate) immunity includes (1) protective barriers – skin and mucous membranes, and their antibacterial secretions; (2) humoral defences – substances in the body fluids, produced or activated when micro-organisms invade, and promoting the function of (3) phagocytic cells – white blood cells and macrophages. acquired immunity (1) active: the result of specific defence mechanisms, each initiated by exposure to a particular antigen and effective against subsequent exposures; includes deliberate immunization by injection of a harmless dose of organisms (alive or dead) or their toxins; (2) passive: for urgent treatment (e.g. of tetanus infection or snake bite) transfer of serum or cells from an already immune individual See also lymphatic system.
impact force the force generated at the start of contact or collision. In sport this can be the impact of a jumper as they hit the ground in the long jump. Impact injury can occur in collision with another person or object when the force exceeds the strength and elasticity of the tissues. Includes both fractures and soft tissue injuries.
impact peak the high point of the sharp increase seen on a force–time trace due to impact between two bodies or objects (or one body or object and the ground).
impingement a term used in sports medicine when soft tissue is trapped, usually between bones, leading to pressure, inflammation, pain and loss of function. Shoulder impingement is common in repetitive overhead sports, especially swimming, where the tendons of the ‘rotator cuff’ are trapped between the head of the humerus and the acromion, causing pain when moving the arm forwards and upwards: the impingement sign. Treatment aims to alter poor technique and reduce inflammation (rest, ice, anti-inflammatory drugs and steroid injections). Surgery is occasionally required.
impression management the act of controlling or regulating information a person gives out in order to influence the impressions formed of them by others.
impulse change in momentum produced by a force. angular impulse moment applied to a rotating body or object multiplied by the duration of the application (newtons×metres×seconds, N.m.s). linear impulse force applied to a translating body or object multiplied by duration of the application (newtons×seconds, N.s).
incremental exercise exercise at gradually increasing intensity, usually achieved by stepwise increments at regular intervals, e.g. on a treadmill (incremental run) or cycle ergometer. Term may also be applied to the shuttle test, where the intervals inevitably decrease as speed increases. See also Bruce protocol.
individual zone of optimal functioning (IZOF) see zone of optimal functioning (ZOF).
induction the derivation of rules and laws by generalizing from observations. Regarded by most 19th-century and earlier philosophers as the essence of scientific procedure, even though Hume had already, in the 18th century, pointed out that every generalization is logically liable to be invalidated by a contrary future observation. Modern thinking recognizes the subsequent development and testing of explanations for the collected observations as at least an equally crucial aspect of science. See also corroborating evidence, falsificationism, model, verificationism.
inertial force an imaginary force introduced to allow for analysis of the acceleration of bodies or objects from the point of view of an accelerating observer.
inertial movement motion without the need for a force. Often occurs when a body segment has been previously accelerated. Consequence of Newton’s first law of motion. See also ballistic movement.
inertial reference frame the use of a co-ordinate system (reference frame) that does not move (i.e. is fixed in space).
inflammation from the Latin inflammare, to set on fire. The term for the pathological process that occurs at the site of tissue damage; a process that enables the body’s defensive and regenerative resources to be channelled into tissues which have suffered damage or are contaminated with abnormal material (such as invading micro-organisms). It also tends to limit the damaging effects of any contamination, to cleanse and remove foreign particles and damaged tissue debris, and allows healing processes to restore tissues towards normality. Fundamentally important for survival. The classic components of the inflammatory response are heat, redness, swelling and pain.
information processing in human brain function, the processes of cognition, including those to do with attention, perception, thinking, remembering, decision making and problem solving. Also parallel meanings in engineering
information theory a mathematical theory of the processing, storage and communication of information which is primarily concerned with the amount of information that needs to be conveyed in order to accurately reproduce or describe any given data.
infrared therapy the use of infrared radiation to produce local heat. Used by physiotherapists as a local treatment to relieve pain and reduce muscle spasm. The scientific evidence as to its effectiveness is poor: it appears to have no greater benefit than other forms of heat therapy.
injury any process causing physical damage. In sport contact injuries result from direct contact with another player or object (e.g. goalpost). These include fractures, ligament injuries, head and neck injuries. overuse injuries result from either an intrinsic cause, such as biomechanical problems, or an extrinsic cause such as the surface of the playing field. In sport, injuries to the lower limb are most common, especially to the knee. The incidence of injury in sport reflects the need for adequate, appropriately trained medical support.
inosine a nucleic acid derivative found naturally in brewer’s yeast and organ meats. Not essential in the diet since the body can synthesize it from amino acids and glucose. Metabolically, takes part in formation of adenine, a component of ATP. It has been suggested that inosine supplementation might enhance exercise performance by increasing ATP supply but research studies have found no improvements. See also ergogenic aids; appendix 4.4.
insertion with reference to a skeletal muscle, the site of its attachment to bone which during its contraction is relatively mobile, compared to the site of its origin. For example, in elbow flexion contraction of the biceps moves the forearm (site of insertion) rather than the scapula (site of origin above the shoulder joint).
inspiration the phase of the breathing cycle when air is being drawn into the lungs.
inspiratory capacity the maximal volume of air that can be inspired after a normal unforced expiration. See also lung volumes.
insulin a polypeptide hormone produced by the beta cells of the islets of Langerhans in the pancreas, associated mainly with regulation of blood glucose, in which it exerts an opposite effect to that of glucagon. Involved also in distribution, utilization and storage of protein and fat, as well as of carbohydrate, and in interconversion among them. Insulin secretion is stimulated by a rising blood glucose concentration and by the parasympathetic nervous system. It lowers blood glucose by promoting its transport into cells (notably muscle and fat cells) and diminishing its output from the liver, and it promotes formation of glycogen in liver and muscle. An absolute or relative lack of insulin results in hyperglycaemia (high blood glucose) and presence of glucose in the urine (glycosuria), along with decreased utilization of carbohydrate and increased breakdown of fat and protein: the condition of diabetes mellitus. Sporting activity by diabetics tends to reduce blood glucose, so good diabetic control with frequent blood sugar testing and adjustment of insulin dosage is important. See also diabetes.
integration (1) in mathematics, the use of calculus to compute the cumulative addition of one variable with respect to another, displayed graphically as the area under the curve of one variable plotted against another; (2) the summing of different types of information; (3) in physiology, coherent function of interacting systems; (4) in society, for example in medicine or social services, the linking of different approaches or organizations.
interactive sport a sport in which a player’s performance or actions can directly affect the performance or actions of opposition players, such as tennis as opposed to golf.
internal force force occurring inside an object or in the body, e.g. by the action of muscles.
internal rotation movement at a joint which rotates the limb, or a part of a limb, inwards, e.g. rotation of the whole arm inwards at the shoulder or rotation of the forearm at the elbow, to bring the palm facing backwards; equivalent movement possible to some extent at the hip but not at the knee. Opposite of external rotation. See appendix 1.2.
International Olympic Committee (IOC) the committee of elected representatives from member countries and sports, which oversees the running and sets the rules of the Olympic Games. The IOC has a Medical Commission, set up in 1966 to oversee doping control. This includes agreeing on the list of banned substances, administering the programme for testing athletes, and implementing appropriate sanctions.
intervertebral discs the soft pads between the bodies of the vertebrae which make up the spinal column. Each disc has an inner spongy gelatinous substance (nucleus pulposus) surrounded by a protective ring of fibrocartilage (annulus fibrosus). The discs contribute to flexibility of the spine and act as shock absorbers. prolapsed intervertebral disc syn slipped disc protrusion of the nucleus pulposus through its fibrous covering into the spinal canal, due to degenerative changes, heavy lifting or injury in sport. Can press on the spinal cord or on the nerve roots, leading to pain, numbness, paraesthesia or even paralysis. Most common in the lumbar region, causing sciatica if the roots of the sciatic nerve are compressed. Diagnosis is clinical with MRI scanning to confirm. Treatment is initially rest with appropriate analgesia, then a programme of core muscle strengthening to prevent recurrence. Persistent neurological symptoms and signs require investigation and, rarely, surgical treatment with minimally invasive microdiscectomy. In sport the commonest disc injuries are in the lumbar and cervical regions, the latter typically in rugby (scrum collapse or direct injury in a tackle), in judo or in a fall from a height as in trampolining or gymnastics. These injuries highlight the need for adequately trained and experienced medical back-up.
intestinal absorption the transfer of the products of digestion, minerals and water (also drugs) from the intestine into the blood or lymph. Food products are absorbed from the small intestine, via its lining of enterocytes (where some further digestive processes take place); hexoses from carbohydrates, and amino acids and peptides from proteins, enter surrounding blood vessels, thence in the portal vein to the liver, which removes some before they reach the general circulation. Lipids enter lymph vessels and these ‘lacteals’ (‘milky’ with fat) join other lymph vessels to reach the thoracic duct, thence to the venous blood. Some water is absorbed from the small intestine, but most from the large intestine.
intestine(s) the parts of the alimentary tract beyond the stomach. Contents leaving the stomach pass in turn through the duodenum, the small intestine (jejunum and ileum) and the large intestine (caecum, colon and rectum) and finally the anal canal. See appendix 1.4 fig 1.
intrafusal fibres muscle fibres within a muscle spindle (‘intrafusal’: Latin, within spindle), invested with afferent (‘sensory’) nerve endings and located so as to detect length changes in the main working (extrafusal) fibres of the muscle. See also gamma (motor) system, motor neurons.
intramuscular haematoma a collection of blood within a muscle. In sport this is usually the result of direct trauma, e.g. a direct blow to thigh or calf in contact sports or muscle tears in non-contact sports. Treatment is aimed at limitation of bleeding (rest, ice, compression and elevation). The collection of blood causes pain, related to either limitation of movement or the increase in pressure in the tissues. If local pressure compromises the circulation, surgery is required to relieve it and to prevent tissue necrosis by draining the haematoma.
intrinsic motivation see motivation.
introversion a personality trait characterized by a focus on one’s own inner world rather than the outside world and a tendency to be reserved and to avoid social situations. The opposite of extraversion. introvert a person who manifests introversion. adj. introverted.
inverse dynamics the calculation of forces and moments by using kinematics and data for mass and moment of inertia, effectively using Newton’s second law of motion (f = ma) in reverse.
inversion with reference to the foot: tilting of the sole inwards. inversion injury a common injury to the ankle joint in sport. Inversion of the foot usually occurs as a result of ‘going over’ on the ankle when the foot strikes the ground, especially if uneven or if the person is off balance. Results in damage to the lateral ligament complex, with bleeding, swelling and pain. Importantly affects proprioception and thus balance, necessitating a formal treatment and rehabilitation programme. See also anterior talofibular ligament; appendix 1.2 fig 3.
inverted-U hypothesis the proposition that performance on a task progressively improves with increases in arousal up to an optimum point, beyond which further increases in arousal lead to progressive decrements in performance. For example, in sport optimal performance is held to occur at a moderate level of arousal. Also known as the Yerkes–Dodson law.
iodine necessary in the diet (as iodides) for the production of the the iodine-containing hormones of the thyroid gland. Deficiency causes hypothyroidism: when severe, in childhood, retarded development (cretinism) and in later life myxoedema.
iron an essential micronutrient; present in the body in the oxygen transport proteins, haemoglobin (60–70% of total iron) and myoglobin (10% of total iron). Small amounts are present in the plasma, carried by the protein transferrin, and it is stored (as ferritin) in liver, spleen and bone marrow. A small component (around 2%) is used in metabolic systems (cytochrome C, in mitochondria). Elite and recreational athletes undertaking hard training have a higher requirement and turnover of iron than less active people and quickly deplete iron stores which if untreated can lead to iron deficiency anaemia, severely impairing aerobic performance.
ironic effects in psychological terms, those that may occur when attempts to suppress a thought increase its accessibility to memory so that it is more likely to be brought to mind, especially under conditions of stress or increased mental load. For example, in a racquet sport if a performer focuses attention on not overhitting the ball they will often do just that. Also known as ironic process.
ischaemia inadequate blood flow to a region, organ or tissue; ischaemic adj. Also known as hypoperfusion.
ischaemic heart disease see coronary artery disease.
ischial tuberosity avulsion detachment of a piece of bone from the tip of the ischial part of the pelvis, where the tendons of the hamstring muscles are attached, caused by their sudden strong forced contraction. This produces local pain, which can be severe. Treatment is difficult and chronic symptoms not uncommon.
isokinetic without change in velocity. isokinetic activity movement of an object, body or body segment, by muscle action, with constant velocity. Sometimes known as isovelocity motion: rare in sport. isokinetic dynamometer device for measuring moments at a constant velocity. The machine controls velocity (usually angular velocity) and external moment is measured. Sometimes known as isovelocity dynamometer. See also torque–angular velocity relation.
isometric contraction contraction in which a muscle stays at the same length, e.g. when holding a weight steady; isometric exercise (syn static exercise) exercise in which this condition obtains. See also force–velocity relationship.
isotonic contraction contraction in which a muscle actively shortens at constant velocity; isotonic exercise exercise in which this condition ideally obtains – in practice approximated by constant angular velocity of limb movement (implying exactly isotonic muscle action only in the theoretical case of the joint concerned having constant geometry throughout the movement range, as in a simple hinge). See also force–velocity relationship.
isotonic solution one that has the same osmolarity as body fluids. Most commercial sports drinks (6% CHO, 20 mmol.L−1 sodium) are isotonic. Isotonic drinks are effective in preventing exercise-induced dehydration and promoting restoration of fluid and electrolyte levels after exercise. See also sports drinks.
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