Relationship Between Internal Load Indicators and Changes on Intermittent Performance After the Preseason in Professional Soccer Players

Abstract

The aim of this study was to examine the effects of accumulated internal training load (ITL) during the preseason (4 weeks) on changes in the intermittent performance, in a professional soccer team. Twelve professionals soccer players (Mean ± SD age: 27.7 ± 4.3 years; height: 177.1 ± 6.2 cm; body mass: 73.1 ± 5.2 kg; % body fat [Faulkner]: 10.2 ± 1.2) belonging to a Spanish second division team (2013-2014) participated in this study. The 30-15 intermittent fitness test was performed before and after the preseason, and the speed for the last period completed by each player was recorded (VIFT). During the preseason, the team alternated practice of training sessions (TRNs) with friendly matches (FMs). Session rating of perceived exertion (sRPE), heart rate (HR), and HR reserve were analyzed every TRN and FM to calculate ITL (ITL: sRPE-TL, Edward's-TL and Edward's-TLres). The players' VIFT substantially increased after the preseason period (20.1 ± 0.8 vs. 21.1 ± 0.8 km·h; effect size [ES] = 1.15 ± 0.25; almost certainly). The average value of sRPE throughout FMs was substantially greater than the value of the TRNs (7.4 ± 0.9 vs. 5.25 ± 0.2; ES = 2.31 ± 2.45; almost certainly). sRPE-TL, practice volume, and sum of RPE during the preseason were positively and largely correlated (r = 0.70-0.75) with changes on intermittent performance. No relationships were found between HR-derived measures of exercise load and changes on intermittent fitness. The present results suggest that practice volume and subjective measures of TL, related better than HR-based TL methods to changes on intermittent performance after the preseason, in professional soccer players.

Associations Between Selected Training-Stress Measures and Fitness Changes in Male Soccer Players

“…12 that showed a curvilinear dose-response relationship between Banister's TRIMP and individualized TRIMP with changes in maximal aerobic fitness. Our findings are, however, in contrast to those of Campos-Vazquez et al 17 who reported no relationship between HR-derived measures of exercise load and changes in VIFT. It is worth mentioning that basal VIFT level of players in the present study was different from the study of Campos-Vazquez et al 17 (VIFT; 19.0 versus 20.1 km•h -1 ) and consequently it might have influenced the dose-response relationships.…”

“…Our findings are, however, in contrast to those of Campos-Vazquez et al 17 who reported no relationship between HR-derived measures of exercise load and changes in VIFT. It is worth mentioning that basal VIFT level of players in the present study was different from the study of Campos-Vazquez et al 17 (VIFT; 19.0 versus 20.1 km•h -1 ) and consequently it might have influenced the dose-response relationships. The relationship between HR-based training loads and fitness changes in the present study are almost similar or of a lower magnitude than have been previously reported using sRPE 17 or HR-based measures [12][13][14][15][16] .…”

“…It is worth noting, however, that most previous investigations were conducted during pre-season preparations when training loads are generally higher 4 and when the main goal of training is to improve players' physical qualities. The smaller improvement in high-intensity intermittent running capacity observed in the present study compared to the change magnitude (ES: 1.15) reported by Campos-Vazquez et al 17 might, therefore, be explained by the different competition phase (i.e. in-season cf.…”

“…The moderate improvement in VIFT observed in our study (~4%, ES: 0.70) is in agreement with previous investigations reporting positive changes in soccer players' fitness after short training interventions 3,[13][14][15]17 . It is worth noting, however, that most previous investigations were conducted during pre-season preparations when training loads are generally higher 4 and when the main goal of training is to improve players' physical qualities.…”

“…Some authors have proposed promising relationships between HRbased training loads and changes in aerobic fitness 10,[13][14][15][16] . Conversely, Campos-Vazquez et al 17 reported no relationship between HR-derived measures of exercise load and changes in highintensity intermittent fitness but showed large-to-very large doseresponse associations when using training duration (r= 0.72) or sRPE (r= 0.70), reinforcing that adding RPE did not improve the dose-response relationship. These differences between studies might be due to different criteria used as the fitness outcome (i.e., lactate threshold, maximal oxygen uptake, and high-intensity intermittent running capacity) that highlights the need to further elucidate the association between training load and the adaptive response to training.…”