M
macronutrients the major foodstuffs: carbohydrates, fats and proteins, required in substantial amounts, to provide a sufficient calorie intake, as well as components that are essential to health. See also dietary reference values, micronutrients; appendix 4.1 fig 1.
magnesium element essential to the life of all body cells, being involved in many enzyme-catalysed processes. The concentration of ionized magnesium [Mg2+] in the body fluids is regulated at the correct level for normal excitability of muscle and nerve, including neuronal activity in the central nervous system. Magnesium is present in bone, and its metabolism is linked to that of calcium and phosphate. See also minerals; appendix 4.3.
Magnus force the force due to the interaction between the surface of a rotating object or body and the fluid medium (e.g. air or water) in which it is rotating. The force acts at right angles to the axis of rotation and, if the object is translating, to the path of the object. Also sometimes classified as a lift force. Examples are topspin causing downward motion of a ball (e.g. tennis) and sidespin causing sideways motion of a golf ball. (Named after the German physicist who described it in the mid-19th century.)
malabsorption impaired absorption of nutrients from the digestive tract. Causes include disease of the small intestine or surgical removal of a major part of it, and lack of digestive enzymes or bile salts.
malalignment while each person has a slightly different joint configuration, malalignment is considered to be the abnormal position of a structure relative to another. In sport it can occur, for example, following incomplete treatment of a fracture and results in loss of function with secondary effects, e.g. malalignment of the tibia following a fracture can result in a variety of overuse injuries including pain in the back, lower limb and/or foot, with restriction of activity.
mallet finger rupture of the extensor tendon from the distal phalanx as a result of a sudden forced flexion, which results in an inability to extend the joint. It may even cause bony avulsion. Common in catching sports, especially when the ball is caught with a partially closed hand. Treatment is by splinting (Stack splint) with the finger held in full extension for about 6 weeks. Surgery is rarely required. Syn hammer finger, baseball finger.
malnutrition the state of being poorly nourished due to the diet containing inadequate micro– and macronutrients. Can result in deficiency diseases, such as scurvy (due to lack of vitamin C). Prolonged or repeated weight-loss attempts are likely to cause nutritional deficiencies.
maltodextrins water-soluble, easily digestible polymers of glucose with low sweetness. As a convenient source of energy (4 kcal per gram) in combination with sugars added for flavour, they are used in sports drinks, energy bars and nutritional supplement beverages. The maltodextrins provide a solution of lower osmolality weight for weight than simple sugars such as dextrose, fructose and glucose and so can deliver more calories at the osmolality of body fluids.
maltose a disaccharide composed of two glucose molecules, present in beer, cereals and germinating seeds, which makes only a small contribution to the carbohydrate content of a normal diet. Also called malt sugar. Broken down by the enzyme maltase to two molecules of glucose.
manipulation the technique of using the hands to move a body part, particularly to return it to its normal position after displacement, e.g. reduction of a Colles’ fracture of the wrist. Manipulation implies a more powerful movement than mobilization and requires skill and experience. Indiscriminate manipulation, especially of the cervical spine, can result in further and serious damage.
marathon specifically, a footrace over a road course of 42.195 km (∼26 mile 385 yd) nowadays covered by elite performers in less than 2 h 10 min (males) and 2 h 20 min (females). Named after the city of Marathon in ancient Greece, imitating the distance run by a messenger from there to Athens, with news of victory over the Persians, in 490 bc. In general, term applied to any form of very high endurance activity.
march fracture a type of stress fracture caused by an increase in physical activity which may so stress a metatarsal (usually the second) as to produce an undisplaced self-healing fracture, with local pain, tenderness and radiographic changes. Management usually involves moderate rest with supportive padding and strapping for a few weeks but sometimes a walking plaster is required. First described in army recruits following prolonged marching.
march haemoglobinuria redness of the urine due to presence of haemoglobin following prolonged walking/running. Occurs due to direct trauma to the blood cells in the vessels in the soles of the feet. Requires no specific treatment but can be minimized by decreasing walking/running on hard surfaces or wearing more appropriate footwear.
march myoglobinuria reddish-brown urine due to the breakdown of muscle myoglobin following strenuous prolonged walking or running.
Margaria staircase test a test of short-term (‘burst’) anaerobic power in which, after a short run-in, the subject runs as fast as possible up a short flight of stairs of specific dimensions. In each of several versions of the test, the length of run-in, rise of each stair and the steps between which speed is measured (e.g. 8th and 12th) are all specified. Timing is by switchmats on the specified steps. Also known as Margaria–Kalamen test.
marijuana (cannabis, grass, hashish) one of the so-called social or recreational drugs, obtained from the hemp plant Cannabis sativa whose active ingredient is tetrahydrocannabinol. The use of social drugs is increasing in society and sport is no exception. UK government statistics have suggested that 40% of 16–18 year olds had taken social drugs in the 12 months period studied. Statistics of their use in sport are difficult to obtain and confirm but are likely to be significant given that the majority of sportsmen and women are young. The effects of marijuana include relaxation, euphoria, sedation, disorientation and a lowering of aggression. It is generally accepted that regular use, and these effects, are not compatible with a training regime required for top-level sport. Current WADA and IOC regulations ban the use of marijuana in competition, but not out of competition. Many believe that in the absence of performance-enhancing effects, an automatic 2-year ban is not justified and that an approach based on education and rehabilitation is preferable, and will assist in maintaining the positive ‘role model’ example to young people.
mass the quantity of material in an object or body. Can be measured in terms of the force needed to accelerate it. Mass is measured in kg and is not to be confused with weight.
massage the use of several soft tissue manipulations (kneading, stroking, rubbing, tapping, etc.) at different depths, rates and strengths. Massage is used in sport to break down adhesions (deep friction), reduce swelling and oedema, and relax muscles. While massage will aid relaxation and reduce muscle stiffness, there is little scientific evidence of any reduction in injury rates.
matching hypothesis the proposition that psychological or behavioural interventions or training programmes should match the presenting problem or personal characteristics of the person being treated or trained. For example, it has been proposed that cognitive-based relaxation techniques should be used to treat cognitive anxiety whereas relaxation techniques designed to reduce physiological arousal should be used to treat somatic anxiety.
Matveyev’s six phases system of athletic training in which the first period consists simply of general body conditioning, the second adds some sport-specific training, the third introduces competition-specific features, the fourth includes preliminary competitions, the fifth is the main competition phase and the sixth is a recuperation period before the next six-phase cycle is commenced. Normally the phase durations are of the order of months, and the complete six-phase cycle lasts a year. (Named after the Soviet scientist who established the system in the mid-20th century.)
maximal heart rate the highest heart rate that can be attained by an individual in strenuous activity, varying with fitness and, in adults, inversely with age. A ‘rule-of-thumb’ formula for the predicted maximum is ‘220 minus age’.
maximal lactate steady state see metabolic and related thresholds.
maximal oxygen consumption (uptake) (
O2 max) the rate of oxygen uptake at the highest work rate an individual can attain and sustain for some minutes, equivalent to aerobic capacity. Measured at the peak of incremental exercise or by extrapolation to predicted maximal heart rate, from successive submaximal measurements of heart rate and oxygen uptake.
maximum voluntary contraction (MVC) maximum force which a human subject can produce in a specific isometric exercise. In practice, usually taken as the best of three efforts in a single test session.
maximum voluntary ventilation (MVV) syn maximum breathing capacity (MBC) the greatest pulmonary ventilation in L.min−1 that a person can attain by deliberately increasing the depth and frequency of breathing.
mean arterial (blood) pressure see blood pressure.
mechanical advantage the difference in forces in a lever system due to the inequalities of the lever arms between the forces and the fulcrum (pivot or axis). See also efficiency.
mechanical energy may be kinetic energy (translational or rotational), gravitational potential energy or elastic potential energy. conservation of mechanical energy in the absence of changes in all other sorts of energy, the total mechanical energy of an object or body will remain constant.
mechanics the study of forces and motion of bodies and objects.
medial (to) in anatomy, describes position of a structure as nearer to the middle of the body, in the coronal (side-to-side) plane, when in the anatomical position. Opposite of lateral.
medial epicondylitis see golfer’s elbow.
medial tibial stress syndrome pain down the inner side of the shin, attributed to periostitis of the tibia. Often called shin splints, although this term is also used for pain at other sites in the leg. The most likely cause is biomech anical, related to such as poor footwear, previous injury (with altered biomechanics) or conditions of the foot such as overpronation.
mediating variable in statistics, a variable that transmits the indirect effects of an independent variable or variables on a dependent variable. For example, the relationship between social support and exercise adherence could be mediated by motivation: social support leads people to be more motivated which in turn leads them to adhere to an exercise programme. See also moderating variable.
medical screening a preventive measure used to identify potential or incipient disease at an early, usually asymptomatic stage, which allays progression and allows treatment. Screening can identify and stratify risk in sport, but the potential benefits must be balanced against the resultant anxiety and the fact that some conditions identified may not be treatable. Routine, organized screening in sport in the UK is uncommon: boxing is an exception with compulsory pre-fight medical examinations and annual CT scanning. Screening is more common in the USA and Italy. In some sports it is compulsory when participants reach a certain level. Screening normally consists of a musculoskeletal assessment (to identify muscle imbalance, degree of flexibility, muscle strength, previous injury, biomechanical abnormalities, etc.) and testing for iron deficiency anaemia in female athletes. Cardiac screening seeks to identify abnormalities which increase the risk associated with participation in sport (especially that of sudden death); this includes a medical questionnaire (personal and family history, symptoms, etc.), clinical examination, ECG and echocardiography. Population screening in sport is indicated and cost-effective when a condition is relatively common, easily identifiable and treatable.
medium-chain triglycerides (MCT) triglyceride molecules containing fatty acids with a carbon chain length of 6–10. Used in sports to provide a rapid source of fatty acid fuel. Their fatty acids are absorbed from the gut into the blood (rather than into lymphatics as are long-chain triglycerides) and thus rapidly reach the liver directly via the portal vein. Entering the general circulation, they rapidly raise the free fatty acids available to the tissues, where they readily enter cells to be used as a fuel. Being oxidized as easily as glucose, they might therefore have liver and muscle glycogen-sparing effects, delaying the onset of fatigue during endurance-type exercise. However, only a few of the numerous studies on MCT supplements have shown an increase in performance, and most reported some gastrointestinal problems. See also ergogenic aids; appendix 4.4.
membrane potential electrical potential difference maintained across a cell membrane, with the inside negative to the outside:−110 mV to−130 mV in non-excitable cells, and −170 to −190 mV (the resting potential) in quiescent excitable cells (nerve and muscle). Due to unequal distributions mainly of potassium and sodium ions (the cell membrane being partially, but not equally, permeable to both) which in turn determines the relative movements of these ions down their respective diffusion gradients (potassium outwards and sodium inwards). The gradients are themselves maintained by the sodium–potassium (Na–K) pump which uses metabolic energy to transport the ions back ‘uphill’. See also action potential, depolarization.
memory short-term memory stores a limited amount of information for a short period of time (up to around 30 seconds); long-term memory lasts from over 30 seconds to many years; working memory a temporary memory store used for manipulating information in and out of short-term memory.
menarche the onset of menstrual cycles.
meniscectomy removal of part or all of a meniscus (semilunar cartilage) from the knee joint.
meniscus syn semilunar cartilage pl menisci flattened crescent-shaped pieces of cartilage inside the knee joint (one medial, one lateral), wedged between the articular surfaces (condyles) of the femur and the tibia and thickest around their convexity towards the outside of the joint. Act as shock absorbers and increase joint stability. meniscal injury is most common in contact sports as a result of trauma, especially with twisting or rotational stress at the joint – especially medial damage due to the attachment of the medial collateral ligament resulting in combined injury. Most tears occur in the outer border of the meniscus, which has a better blood supply and is thus more easily repaired, but cartilage repair is not favoured by professional sportsmen due to the time (and finance) lost from sport in the extended rehabilitation period. Many opt for removal of the torn fragment – partial meniscectomy – with its quicker return to action. Surgical treatment aims to minimize the amount of meniscus removed to limit the extent of later osteoarthritis. Sometimes a tear can heal spontaneously. It may result in the development of a cyst or a fragment may break off, forming a loose body inside the joint; either of these is likely to require surgical removal.
menstrual cycle in women, normally from the menarche to the menopause except when interrupted by pregnancy, the 4-week cycle under the control of pituitary and ovarian hormones, that ends with menstruation. The cycle appears to have little or no negative impact on women’s athletic performance, despite the physiological changes that occur. Studies of 
O2 max during different phases of the cycle have shown no disadvantageous effect on performance despite subjective feelings of bloating and fatigue (seen with premenstrual syndrome) and the known effects of oestrogen and progesterone on oxygen utilization. Indeed, studies have shown that world records have been set during all phases of the menstrual cycle. See also amenorrhoea, female athletic triad.
mental practice see mental rehearsal.
mental preparation the act of mentally preparing oneself for a performance.
mental rehearsal the use of imagery to practise an act mentally. In sport psychology, mental rehearsal is considered to be one of the fundamental mental skills for sports performers and is used for learning new skills, practising existing skills, preparing for performance and enhancing motivation. Also known as mental practice.
mental skills the set of trainable mental abilities and methods that are held to underpin successful learning and performance. The basic mental skills include concentration, goal-setting, imagery and mental rehearsal, relaxation and self-talk. Also known as cognitive skills and psychological skills.
metabolic acidosis see acidosis.
metabolic alkalosis see alkalosis.
metabolic and related thresholds intensities of exercise (expressed as power output or as percentages of aerobic capacity, 
O2 max) at which specific metabolic and related changes are considered to take place. A plethora of thresholds has been proposed historically. These included many giving the same label to different criteria, or different labels to the same criterion; a number also embodied assumptions about bodily processes, at best unproven and sometimes now known to be false. The table lists six which appear unambiguous, the first five exactly as first described and the sixth slightly modified; however the two that are not related to observable phenomena (anaerobic and aerobic thresholds) are not recommended for further use. The [Lac]b (blood lactate concentration) values cited are representative approximations for a healthy but untrained young adult; they are used in some laboratories as working indices, but should not be taken as definitions of the term concerned. Other usages in the literature include: (1) OBLA as equivalent to LT or AT – confusions possible only if the reference to continuous rise is omitted from the OBLA definition; (2) the 4 mmol.L− criterion being designated as any one of ‘anaerobic’, ‘aerobic’ or ‘aerobic/anaerobic’ thresholds. See table overleaf.
metabolic equivalent (MET) expresses the approximate energy cost (in terms of oxygen consumption) of a particular activity relative to the energy expenditure at rest, i.e. at rest MET = 1, equivalent to oxygen consumption of about 3.5 mL O2 kg−1.min−1. Scores for over 500 different activities are reported in a comprehensive and well-validated list in the Compendium of Physical Activities, e.g. walking at 3 mph: 3.3 MET; running at 8 mph: 13.3 MET. The total daily energy expenditure can be calculated, knowing body mass, the time spent in each activity and the relevant MET scores.
Metabolic and related thresholds
| Term | Definition | [Lac]b mmol: L−1 |
|---|---|---|
| Lactate threshold (LT, Tlact) | Minimum work rate at which [Lac]b is found, at least in the early minutes, to be significantly above (sometimes defined as 1 mmol: L −1 above) resting value | 2 |
| Anaerobic threshold (AT) | Work rate at which it has been considered that shortfall in oxygen supply to working muscles causes them to begin drawing on anaerobic pathways. < div class='tao-gold-member'>
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