Author(s): HSUEH, C.L., CHANG, C., Institution: NATIONAL TAIWAN UNIVERSITY OF SPORT, Country: TAIWAN, Abstract-ID: 855

INTRODUCTION:
This study investigated the effect of pre-match caffeine supplementation on the performance in rugby seven matches in collegiate male players.
METHODS:
This study adopted a placebo-controlled crossover design. Seven participant engaged in two rugby sevens friendly matches each day on two consecutive days, separated by a 13-day washout period. The participants in the caffeine trial (CA) consumed 3 mg/kg body weight caffeine in a capsule 1 h before each match, while those in the placebo trial (PL) consumed a capsule containing starch. Movement patterns during the matches, including total distance, distance in several speed zones, distances and frequency of acceleration and deceleration, and frequency of collisions and repeated high-intensity effort (RHIE), were recorded using wearable GPS devices. The differences between the two trials in movement patterns in the entire match and first and second halves were analyzed with paired t-test and effect size was calculated using Cohen’s d.
RESULTS:
The participants in CA exhibited longer total distance in the match 1 (CA: 1485.8 ± 67.9 ; PL: 1346.9 ± 83.8 m, d=0.743), 3 (CA: 1394.7 ± 50.3; PL: 1312.9 ± 46.6 m, d=0.690), and 4 (CA: 1502.5 ± 89.9; PL: 1359.2 ± 67.5 m, d=0.736) with moderate effect sizes. The increased distance came mostly from faster speed zones. The participants in CA had longer distance in high intensity running (18-20 km/h) in match 1 (CA: 90.6 ± 25.1; PL: 54.1 ± 10.6 m, d=0.773) and 4 (CA: 76.5 ± 18.1; PL: 58.7 ± 11.6 m, d=0.479). The participants in CA had longer distance in acceleration in match 1 (CA: 58.03 ± 3.76; PL: 49.89 ± 5.45 m, d=0.710) and 3 (CA: 64.51 ± 5.59; PL: 51.85 ± 9.54 m, d=0.661). Conversely, the participants in PL walked (0-6 km/h) longer distance in match 4 (CA: 585.9 ± 21.8; PL: 629.4 ± 21.3 m, d=0.824) with large effect size. The participants in CA had higher frequency of RHIE in the first half in match 1 (CA: 4.83 ± 0.75; PL: 3.50 ± 0.56, d=0.822) and 3 (CA: 4.67 ± 0.42; PL: 3.33 ± 0.49, d=1.185) and the second half in match 4 (CA: 5.00 ± 0.45; PL: 4.17 ± 0.70, d=0.577). The participants in CA also had higher frequency of collision in the first half in match 1 (CA: 2.50 ± 0.89; PL: 1.00 ± 0.52, d=0.845) and 4 (CA: 2.17 ± 0.48; PL: 1.33 ± 0.62, d=0.618) and the second half in match 4 (CA: 2.67 ± 0.80; PL: 1.17 ± 0.40, d=0.965). Moreover, the participants in CA exhibited higher frequency of deceleration in the first half in match 1 (CA: 9.50 ± 1.20; PL: 7.00 ± 0.73, d=1.025), 2 (CA: 9.00 ± 1.21; PL: 7.33 ± 1.17,d=0.571), 3 (CA: 10.50 ± 1.71; PL: 6.17 ± 1.01, d=1.260), and 4 (CA: 9.67 ± 1.17; PL: 8.17 ± 1.14, d=0.530).
CONCLUSION:
The results of this study suggested that caffeine supplementation before rugby sevens matches may improve overall and high intensity running distance and increase the frequency RHIE, collision, and deceleration in male collegiate players.