Game Demands of Seven-A-Side Soccer in Young Players.

Barbero-Alvarez, JC, Gómez-López, M, Castagna, C, Barbero-Alvarez, V, Romero, DV, Blanchfield, AW, and Nakamura, FY. Game demands of seven-a-side soccer in young players. J Strength Cond Res 31(7): 1771-1779, 2017-The aim of this study was to examine the activity patterns and physiological demands of 7-a-side youth soccer matches across 2 chronological age categories (U12 and U14). Twenty-two soccer players of a national youth soccer academy were investigated. Players of each age category performed 2 training matches (2 × 25 minutes) and were monitored by global positioning system and heart rate monitor units. Players of both categories covered similar total distance (5,348 ± 307 m), at similar mean heart rate values (86 ± 4% of maximum). However, the number of high-intensity runs (82.5 ± 17.4 vs. 69.7 ± 15.2) and total distance covered during sprints (264 ± 207 vs. 128 ± 74 m) were significantly (p ≤ 0.05) higher in U14 compared with U12. The results suggest a highly demanding nature of 7-a-side soccer for skilled players, with physical maturity possibly influencing the match-related high-intensity performance at these ages.

The validity and reliability of a global positioning satellite system device to assess speed and repeated sprint ability (RSA) in athletes.

There is a limited understanding of the validity and reliability of commercially available global positioning satellite (GPS) devices for assessing repeated sprint performance in athletes. The aims of this study were to assess the convergent validity and the test-retest reliability of a GPS device for measuring repeated sprint ability test (RSAT) variables. Two groups participated in this study, a group of 21 physical education students (age: 20.2+/-2.3 years, stature: 1.75+/-0.42 m, body mass: 68.0+/-6.8kg) and a second group 14 elite junior soccer players (age: 14.5+/-1.2 years, stature: 1.60+/-0.09 m, body mass: 57.7+/-3.8kg) volunteered to participate in this study. Convergent validity was assessed as the correlation between sprint performance (15 and 30-m) using both timing lights and a portable GPS device during a RSAT (7 x 30-m sprints with 30-s of active recovery). The 7 x 30-m RSAT test-retest reliability using GPS device was assessed in elite junior soccer players repeating the test 1 week apart and expressing reliability as a coefficient of variation. Results showed a strong correlation between peak speed measures with the GPS device and RSAT performance measured with timing lights for the 15-m (r(2)=0.87, p<0.001, N=147) and 30-m (r(2)=0.94, p<0.001, N=147) splits, respectively. There was a low coefficient of variation for summated maximal speed (1.7%) and peak speed (1.2%) during the 7 x 30-m RSAT, but high variation for the percentage decrement score (36.2%). These results provide evidence to support the use of the GPS device as an alternative measure to assess repeated sprint performance but suggest a percentage decrement score is not a reliable measure of RSAT performance.