Accuracy and reliability of the InBody 270 multi-frequency body composition analyser in 10-12-year-old children.

The aim of this study was at examining the validity and reliability of a marketed bioimpedance (BIA) scale for body composition assessment, in children engaged in an educational football project (FIFA 11 for Health). One-hundred and twenty-seven children (70 boys and 57 girls; age 10.7±0.5 years, body mass 41.2±9.0 kg, Body mass index 18.5±3.3 kg·m-2 and stature 149±7 cm) were evaluated for total body mass, lean body mass, muscle mass, using BIA (InBody 270, Biospace, California, USA) and dual-energy X-ray absorptiometry (DEXA, Lunar Prodigy, GE Medical Systems, Madison, Wisconsin, USA), at baseline conditions. Data analyses were carried out separately for girls and boys. Nearly perfect associations (r = 0.97-0.99) and excellent absolute (TEM = 0.04-1.9%) and relative (ICC = 0.98-1.00) inter-device reliability were found between DEXA and BIA variables. Fat and lean body mass bias (p < .0001) were practically relevant both for the boys (2.56 and 11.22 kg, respectively) and the girls (2.33 and 10.49 kg, respectively). Muscle mass and body fat were underestimated and overestimated, respectively, for the boys and girls. InBody 270 is a valid BIA system for estimating body composition with an excellent inter-device relative and absolute reliability. However, the remarkable measurements bias of BIA fat and muscle mass values discourage its use for clinical prescription. The BIA body composition biases were sex dependent.

The Effects of Long Sprint Ability-Oriented Small-Sided Games Using Different Ratios of Players to Pitch Area on Internal and External Load in Soccer Players.

PURPOSE: To examine the internal and external load imposed by long sprint ability-oriented small-sided games (SSG) using different ratios of players to pitch area (densities) in soccer players. METHODS: A total of 19 professional soccer players from the same soccer club (age = 17.1 [0.3] y, height = 1.76 [0.69] m, and body mass = 69.7 [9.4] kg) participated in this study. Players performed 4 × 30-s (150 s recovery) all-out 1-vs-1 SSG considering 300, 200, and 100 m2 per player (48 h apart). Players' external loads were tracked with global positioning technology (20 Hz). Heart rate, blood lactate concentration (BLc), and rating of perceived exertion characterized players' internal load. Peak BLc was assessed with a 30-s all-out test on a nonmotorized treadmill (NMT). RESULTS: SSG300 produced higher BLc than SSG200 (moderate) and SSG100 (large). The SSG300, SSG200, and SSG100 BLc were 97.8% (34.8%), trivial; 74.7% (24.9%), moderate; and 43.4% (15.7%), large, of the NMT30s peak BLc, respectively. Players covered more distance at high intensity during the SSG300 than in other SSG conditions (huge to very large differences). High-intensity deceleration distance was largely lower in SSG200 than in SSG300. SSG100 elicited very large to huge and large to very large lower external load values than SSG300 and SSG200, respectively. CONCLUSIONS: The main finding of this study showed an inverse association between ball-drill density and internal/external loads in long sprint ability-oriented SSG. The SSG300 provided BLc closer to individual maximal, thus satisfying the all-out construct assumed for the development of long sprint ability. Further studies using the SSG300 as a training intervention and/or investigating other different SSG formats using the same density are warranted.