# Body Composition in Karate: A Dual-Energy X-ray Absortiometry Study
## 1 Introduction  
Karate is a martial art born in Japan, which is nowadays practiced all over the world. Recent data [1] show that the number of karate practitioners around the world is >100 million, belonging to about 200 national federation. Moreover, the program of the Tokyo 2020 Olympic Games included karate as an additional sport. Karate is an intermittent combat sport, which is physically demanding, dynamic, and high intensity, involving repeated bouts of strikes and defenses, performed as explosive and technically demanding sequences [2]. Accordingly, karate requires both aerobic [3] and anaerobic [4] capabilities. Speed, agility, coordination and balance, and a high level of other motor and functional abilities are required to successfully perform in karate [5]. It has been shown that continuative karate training improves physical qualities including flexibility, strength, balance, and cardiorespiratory fitness [6].  
It is well known that athletic success is influenced by diverse factors, from morphological and body composition characteristics to sport-specific skills [7, 8]. In particular, it has been shown that the practiced discipline affects the athletes' physical characteristics. While these physical traits (e.g., stature and skeletal muscle cell number) are largely determined by genetic factors, they are, to some extent, dependent on environmental factors, e.g., systematic conditioning and dieting, the most observable effects affecting body composition with an increase of lean body mass (and muscular strength), and a concomitant reduction in fat mass [9]. Karate has weight competition categories ranging from <60 kg to >84 kg for male and from <50 kg to >68 kg for female athletes.  
Ten years ago, a review [10] on the anthropometric, physical, and physiological profile of elite karate athletes showed that information on the body composition of karatekas came essentially from anthropometry and prediction equations. Percent body fat was the most investigated variable, ranging from 7.4 to 18.6% (males and females). Only one paper assessed three-compartment body composition using dual-energy X-ray absorptiometry (DXA) in a small (n = 14) sample of male athletes [11]. In the following years, a limited number of papers dealt with the body composition of adult (>18 y) karatekas, typically using bioelectric impedance analysis (BIA) [12; 13; 14] or skinfolds [15; 16; 17]. Currently, the gold standard for the assessment of body composition is the four-compartment method (4C); however, DXA outputs are accurate and precise enough to reliably differentiate lean and fat tissues in addition to mineral [18; 19]. Instead, two review papers recently showed that the predictive equations developed using BIA lead to large variability in the estimated value of fat-free mass vs. DXA being population- and device-specific [20; 21]. It has also been shown that BIA may overestimate fat-free mass and underestimate FM vs. DXA in athletes [22; 23; 24; 25]. Based on the above, the present work aimed at defining the body composition of karatekas in a large sample of male and female athletes using the laboratory reference method DXA. Given the possible relevance of asymmetries in the body composition of martial sports athletes [26; 27], we also conducted a preliminary study comparing right and left upper and lower limb compartments.