text: INTRODUCTION 
  healthy aging (5). However, our knowledge of extreme human 
  strength is limited. 
  
  To date, there is little scientiﬁc information on the charac- 
  teristics of extremely strong humans in terms of laboratory- 
  based tests of strength and power, particularly the size and dis- 
  tribution of their muscle mass, as well as tendon size and joint 
  mechanics (moment arm). Kraemer et al. (6) examined the 
  body composition of elite strongman competitors using dual- 
  energy X-ray absorptiometry scanning and found that they 
  had a body mass (153 ± 19 kg) and lean mass (118 ± 12 kg) 
  approximately twice that of an average untrained healthy 
  young man. Whole body skeletal muscle mass of athletes from 
  strength- and power-based sports has also been estimated 
  using ultrasound measurements at a limited number of ana- 
  tomical locations (7, 8). However, neither ultrasound-derived  Feats of strength have fascinated man since the early stages 
  of human civilization, as shown by the archeological evidence 
  of inscribed heavy stones at Olympia and Thera in Greece, 
  dated to the 6th century BC, detailing the way they were lifted 
  by Bybon and Eumastus, respectively (1). Over the centuries, 
  many types of strength competitions have existed; some of 
  which have been codiﬁed and endured within modern sport- 
  ing competitions (e.g., weightlifting, powerlifting, and shot 
  put). In addition, professional strongman competitions, such 
  as the annually contested “World’s Strongest Man” event, 
  generate extensive global interest (2). Moreover, scientiﬁc 
  understanding of muscular strength is important because of 
  its role in athletic performance (3), injury prevention (4), and 