Different training load quantification methods and endurance improvement during preseason in elite soccer players.

Training load quantification plays an important role in performance maximization and injury prevention in elite soccer. The aim of the present study was to quantify the internal training load (TL) of elite soccer players during an 8-week preseason period. A second aim was to investigate the relationship between total internal TL measures and changes in aerobic fitness during the preseason period. The quantification of internal TL of sixteen elite professional soccer players was assessed using the session rating of perceived exertion (s-RPE) and a heart rate (HR) based method (Edwards-TRIMP) during an 8-week preseason period. Aerobic capacity was measured both in field (interval shuttle run test-ISRT) and a using VO2max laboratory test before and after the preseason. Total s-RPE, TL, and Edwards-TRIMP were significantly (p<0.05) higher during the second and third weeks compared to the other weeks of preseason. The VO2max, v-VO2max, and distances completed during ISRT were significantly (p < 0.05) improved after the preseason period by 3.3+2.1%, 14+6%, and 29+16%, respectively. No relationship was found between the changes in aerobic parameters and total s-RPE TL or Edwards-TRIMP during the preseason period. The relative time spent in high heart rate zone (90-100% HRmax) was significantly correlated (p<0.01) with the relative changes in distance completed during ISRT. These results provide critical information about the periodization of internal TLs during preseason in elite professional soccer players. In addition, the proportion of time spent in high HR zone during preseason is an essential load monitoring factor, which is correlated with aerobic improvements during the preseason in elite soccer players. [ABSTRACT FROM AUTHOR]