Effect of time of day on soccer specific skills in children: psychological and physiological responses

The aim of this study was to examine the effect of time of day on soccer-specific skills and physiological and psychological parameters in children. Ten male children soccer players (age: 14.6 +/- 0.8years; height: 1.63 +/- 0.4m; body mass: 52.5 +/- 4.9kg) performed two shooting accuracy tests before and after a 10x20-m dribbling sprint test with 20-s of passive recovery between repetitions. The measurements were taken at 08:00h, 13:00h, and 17:00h in a randomized order. Mean heart rate (HR) was monitored during the dribbling test. At the beginning of each test session, blood pressure and intra-aural temperature were measured. Likewise, children were asked to complete the profile of mood state (POMS) and the Hooper Index questionnaires. Lactate concentration ([La]) was recorded at rest, post-fifth recovery periods and post-second accuracy test. Moreover, they indicate their rating of perceived exertion (RPE) score immediately at the end of each test session. The results of this study showed that dribbling performance was higher at 13:00h and 17:00h in comparison with 08:00h (p<0.05). Likewise, intra-aural temperature, RPE scores, depression recorded by the POMS questionnaire, and the stress recorded by the Hooper questionnaire were higher in the afternoon (p<0.05). However, the fatigue during the 10x20-m dribbling sprint and the kicking accuracy were not affected by the time of day. Moreover, [La], mean HR, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were not affected by the time of day. For the correlations analysis between all parameters, the statistical analysis showed significant correlation only between TT and RPE scores and between MT and RPE scores (r=0.6, p<0.05). In conclusion, shooting accuracy was not affected by the time of day. However, dribbling performance of children is better in the afternoon than in the morning. This diurnal variation could not been explained by variation in mood or in [La], mean HR, SBP, and DBP.