• Body composition methodology
• Weight loss
• Assessing validity and reliability of test of physiological parameters
• Elite performance
• Ultrasound

Body composition is an important determinant of health and performance. In ‘weight-sensitive sports’, among which are aesthetic sports, weight class sports and gravitational sports (in which body weight influences performance), many athletes use extreme methods to reduce weight rapidly or maintain a low body weight in order to gain a competitive advantage. As a consequence, athletes with very low bodyweight, extreme weight changes due to dehydration or eating disorders, extremely low body fat content, or insufficient bone mineral density are encountered with increasing frequency in many sports.1–5 In weight-sensitive sports, low bodyweight should be seen as only one possible performance factor among others. A deliberately induced underweight condition or short-term weight reduction may lead to severe medical problems, and loss of tissue can cause disastrous performance setbacks due to decreased muscle strength, general weakness, increased susceptibility to illness and reduced ability to cope with pressure: in extreme cases, athletes may develop a clinical eating disorder which is accompanied by severe mental and physical effects that may prove fatal.1 ,6 ,7

The health of the athlete is a precondition for optimum performance. Adipose tissue functions as an endocrine organ and is important in terms of health; it is not just ‘ballast’, as might be …