RESUMEN
This study compared the effects of two breathing conditions during the freestyle turn approach phase in swimmers. Thirty-four prepubertal swimmers (mean ± SD: 10.59 ± 0.97 years) were divided into two groups: No Breath (NB), not breathing at the last stroke, and Breath Stroke (BS). Swimmers performed three turns with 5 min of rest between the repetitions. Kinematic parameters were recorded with two underwater and two surface cameras. Total turn time (NB: 9.31 ± 1.34 s; BS: 10.31 ± 1.80 s; p = 0.049), swim-in time (NB: 3.89 ± 0.63 s; BS 4.50 ± 0.79 s; p = 0.02) and rotation time (NB: 2.42 ± 0.29 s; BS: 3.03 ± 0.41 s; p = 0.0001) were significantly shorter and swim-in distance [NB: 0.70 (0.58,0.77) m; BS: 0.47 (0.34,0.55) m; p = 0.0001], glide distance (NB: 1.06 ± 0.21 m; BS: 0.70 ± 0.20 m; p = 0.0001) and surfacing distance [NB: 1.79 (1.19,2.24) m; BS: 1.18 (0.82,1.79) m; p = 0.043] were significantly longer in NB than in BS. Moreover, speed-in (NB: 1.04 ± 0.14 m/s; BS: 0.93 ± 0.14 m/s; p = 0.031) and push-off speed (NB: 2.52 ± 0.30 m/s; BS: 1.23 ± 0.20 m/s; p = 0.001) were significantly higher in NB than in BS. Swim-in time was positively and negatively correlated with rotation time and glide distance, respectively, whilst negative relationships between total turn time and swim-in distance, total turn time and surfacing distance and total turn time and speed-in were found. Our study showed that in prepubertal swimmers not breathing at the last stroke during the approach phase positively affected kinematic parameters of the turn, allowing to approach the wall faster, rotate the body quicker, increase push-off speed, reduce turn execution time, thus improving overall turn performance.
RESUMEN
Beef is a nutrient-rich, high-quality protein containing all the essential amino acids in proportions similar to those found in human skeletal muscle. In order to investigate the efficacy of a beef supplementation strategy on strength and body composition, we recruited 26 young healthy adults to participate in a resistance-training program of eight weeks, based on the use of isotonic machines and free weights at 75% of one repetition maximum. Subjects were randomly divided into two groups, food group and control group, of 12 and 14 subjects respectively. Food group were supplemented after resistance training with a 135 g serving of lean beef (tinned meat), providing 20 g of protein and 1.7 g of fat. No supplementation was provided to control group. Fat mass, fat free mass, lean mass, assessed by bioelectrical impedance analyzer, and muscle strength, assessed by one repetition maximum test, were evaluated in all subjects both at the beginning (week 0) and at the end (week 8) of the study. Pre- and post-training differences were evaluated with paired t-tests while group differences for each outcome parameter was evaluated with independent t-tests. At the end of the study the food group showed a significantly decrease in fat mass (week 0: 15.0 ± 6.7 kg; week 8: 13.1 ± 7.6 kg; Δ: -1.9 ± 2.9 kg; p < 0.05) and a significantly increase in fat free mass (week 0: 52.8 kg ± 9.4; week 8: 55.1 kg ± 10.9; Δ: 2.3 ± 2.5 kg; p < 0.01). No significant differences in lean mass were found in either food group or control group. No significant differences in one repetition maximum tests were found between food group and control group. Tinned meat can be considered a nutrition strategy in addition to other proteins or amino acid supplements, but as with any other supplementation strategy, a proper nutrition plan must be coupled.