Conventional Warm-up on Physical Performance in Children Soccer Players

Effect of Conventional Warm-up Regarding to Stretching Warm-up on Physical Performance in Children Soccer Players

Considering the importance of an optimal warm-up to enhance performance in key soccer-related variables such as jump height, sprint speed, and ball kicking velocity, most available evidence to date has focused on youth and adult players, with limited studies conducted in children. Therefore, this study aimed to assess and compare the effects of a conventional warm-up and warm-ups including static stretching condition (SSC), dynamic stretching condition (DSC), and ball-specific condition (BSC) on jump performance countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ) as well as on curve sprint speed, the Illinois change of direction test (ICODT), and ball kicking speed in male child soccer players. We hypothesized that the dynamic stretching warm-up would produce superior performance across most variables compared with the other conditions, due to its potential benefits for neuromuscular activation and optimization of the stretch shortening cycle.

This randomized crossover trial will investigate the acute effects of four different warm-up protocols on the physical performance of youth soccer players. Participants will complete four warm-up conditions in random order: (i) conventional warm-up (CC), without flexibility exercises; (ii) static stretching condition (ESE); (iii) dynamic stretching condition (EDD); and (iv) ballistic stretching condition (ESC). Each condition will be separated by a 72-hour rest period.

After each warm-up, participants will undergo jump performance assessments including countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ), corner sprint speed, agility using the Illinois Change of Direction Test (ICODT), and striking velocity with their dominant and non-dominant legs. Anthropometric measurements (height, body mass, and BMI) will be obtained according to ISAK standards. Warm-up protocols will be standardized to 10 minutes and their intensity will be adjusted using the Rate of Perceived Exertion (RPE) scale, progressing from moderate intensity (3-5 points) to vigorous intensity (6-8 points). Data normality will be verified using the Shapiro-Wilk test, and differences between conditions will be analyzed using a one-way ANOVA with Bonferroni post hoc correction. Effect sizes will be calculated using Cohen's d, with statistical significance at p < 0.05.

This study will aim to determine which warm-up method most effectively improves key soccer performance variables (jumping ability, sprinting, agility, and striking speed) in children, providing evidence for optimizing pre-competition routines in youth soccer.

Inclusion Criteria:

• Male children aged 8 - 13 years, enrolled in a soccer school affiliated with amateur clubs in Chile.
• Regular participation in organized soccer training (≥2 sessions per week) for at least six months prior to the study.
• Absence of musculoskeletal or neurological injuries that could limit the ability to perform the warm-up or physical performance assessments.
• Availability of appropriate sports clothing and footwear for testing sessions.
• No concurrent participation in other soccer schools or competitive teams during the study period.
• No official matches or competitions scheduled on the same days as the experimental sessions.
• Signed assent and informed consent provided by the participant and a parent or legal guardian, respectively.

Exclusion Criteria:

• Sustain an injury or illness during the study period that prevents participation in testing.
• Fail to complete all four experimental conditions or physical assessments.
• Demonstrate non-compliance with the warm-up instructions or assessment procedures.