2016, Volume 12, Issue 1
Changes in body composition due to weight reduction by elite youth judo athletes in short period pre-competition
Lucia Mala1, Tomas Maly2, Frantisek Zahalka1, Michal Dragijsky1
1Sport Research Centre, Charles University in Prague, Faculty of Physical Education and Sport, Prague, Czech Republic
2Sport Research Centre, Charles University in Prague, Faculty of Physical Education and Sport, Praha 6, Czech Republic
Author for correspondence: Lucia Mala; Sport Research Centre, Charles University in Prague, Faculty of Physical Education and Sport, Prague, Czech Republic; email: tomimaly[at]yahoo.com
Author for correspondence: Tomas Maly; Sport Research Centre, Charles University in Prague, Faculty of Physical Education and Sport, Praha 6, Czech Republic; email: tomimaly[at]yahoo.com
Background & Study Aim: The majority of judo athletes do not maintain their body weight by elimination of fat mass; rather, they reduce body weight shortly before competition. The aim of the study is effect of weight reduction by elite youth judo athletes in short period pre-competition.
Material & Methods: Study participants included 10 elite youth judo athletes (age 22.1 ±2.8 years, weight 80.03 ±11.8 kg, height 183.0 ±4.2 cm) whose body composition was measured using bioelectrical impedance before and after pre-competitive weight loss (6 days on average, using dehydration). We used the BIA 2000M bio-impedance method in two periods (pre- and post-reduction period) 6 days apart.
Results: The results showed significant changes in directly measurable indicators of body composition (resistance, reactance, phase angle) due to intentional body weight reduction in judo athletes. Resistance after weight reduction increased by 22.26% (Mpre-test: 373.60 ±34.94 Ω, Mpost-test: 480.60 ±47.17 Ω, t9 = −8.44, p<0.01, d = 0.96). We also detected significantly higher reactance (Mpre-test: 50.90 ±6.52 Ω, Mpost-test: 59.60 ± 6.33 Ω, t9 = −9.11, p<0.01, d = 1.05). Due to a higher increase in resistance (22.26%) in comparison to reactance (14.60%), the phase angle decreased significantly (Mpre-test: 7.54 ±0.91 °, Mpost-test: 7.24 ±1.05 ° t9 = 5.031, p<0.01, d = 1.26). A significant proportion of body weight loss was represented by a decrease in total body water (Mpr ECWe-test: 52.87 ± 5.59 l, Mpost-test: 47.73 ±6.17 l, t9 = 8.20, p<0.01, d = 1.37).
Conclusions: Alternating resistances and the associated phase angle can be considered an option to eliminate a possible source of errors (condition of constant hydration, usage of a specific prediction equation when calculating fat-free mass, body cell mass and fat mass).
Key words: resistance, reactance, phase angle, bio-impedance analysis, body weight loss