Chapter 12 Hazards

Chapter overview Introduction Musculoskeletal injuries Sudden cardiac death, triggering of heart attack Female athlete triad Impaired immune function Prevention Summary

Musculoskeletal injuries 50% of people participating in team sports sustain at least one injury over a season. There are two categories of injury, overuse and acute traumatic. The majority are to the lower limb, two out of three during team sports. Running injuries have predisposing factors: –weekly distance run; –previous injury; –lack of running experience; –running to compete; –a rapid increase in training distance or intensity; –running on hard surfaces or in poor shoes.

Injuries reported during a moderate- intensity physical activity intervention

Exercise-related cardiac events Individuals invariably have existing heart disease. young adults, usually hereditary or congenital cardiovascular abnormality; older people, mainly atherosclerotic coronary artery disease.

Relative risk of MI during heavy exertion, according to the frequency of regular heavy exertion

Prevalence of components of the Female Athlete Triad in elite Norwegian athletes and controls

Female athlete triad Its defining feature, low energy availability, impairs both reproductive function and bone turnover, with potentially important clinical consequences.

First study of amenorrhoea in women runners, 1977

Secondary amenorrhoea in athletes Prevalence 3–66%, according to sport and criteria adopted, compared with 2–5% in general population; not only sportswomen – 40% of ballet dancers; reproductive function can be impaired in absence of amenorrhoea; predisposing factors: –youth; –low body fat; –high training intensity and/or volume.

Spinal BMD is inversely related to duration of amenorrhoea

J-shaped relationship: innate immune function and exercise intensity and/or volume

Exercise affects adaptive and innate immune systems The adaptive system detects a specific invading organism (specific recognition). The innate system detects such organisms in a non-specific manner No single marker for respiratory tract infection has been used as a surrogate marker. Prolonged session of high-intensity endurance exercise leads to transient but clinically important changes in immune function.

Hazard prevention Moderate amounts and intensity of exercise; helmets, mouth-guards, shin- and knee-pads; cycling – helmets, lights, reflective clothing; education – coaches, participants and parents: –discouraging foul play; –early recognition of overuse injury; –rehabilitation after injury; –gradual entry into conditioning programmes for the previously sedentary; –discouraging restrictive eating and increasing understanding of nutritional principles.

Summary I Participation in vigorous exercise or sports carries risks. The majority of musculoskeletal injuries are to the lower limb. Two out of three occur during team sports. Vigorous exertion can acutely and transiently increase the risk of sudden cardiac death and heart attack in people with existing cardiac disease. This increase is highest among people unaccustomed to such exercise.

Summary II The Female Athlete Triad, common in sports that emphasize leanness, comprises: irregular/absent menses, disordered eating and low BMD. BMD is low in amenorrhoeic athletes. This bone loss may be largely irreversible. Immune function may be compromised for some hours after prolonged vigorous exercise. Moderate amounts and intensities of exercise are associated with few hazards.