Effects of SAQ Training on Sprint and Agility in Preadolescent Soccer Players

Study Introduction and Objectives

Purpose of the Study: To examine the effects of Speed, Agility, and Quickness (SAQ) training on 5 m and 20 m acceleration, change of direction speed (CODS), and reactive agility in preadolescent (under-11) soccer players.
Definitions & Concepts:
- SAQ (Speed, Agility, and Quickness): A specialized training approach combining high-rate movement tasks (Quickness), straight-line sprinting (Speed), and multi-directional sprints with or without cognitive stimuli (Agility).
- Anaerobic Fitness: Crucial for winning ball possession, dribbling, and scoring.
- Closed Skill Activities: Such as Change of Direction Speed (CODS), which involve planned movement patterns.
- Open Skill Activities: Such as Reactive Agility, which requires reactions to unpredictable external stimuli (e.g., an opponent's movement).
Hypothesis: The researchers hypothesized that SAQ training would be more effective than sport-specific training alone for improving acceleration, CODS, and reactive agility in preadolescent athletes.
Significance: Despite evidence in young adults, the effectiveness of SAQ training in middle childhood (the "sampling stage," ages 6–12) needed investigation to guide youth coaches.

Participant Demographics and Study Design

Initial Sample: 39 sub-elite young soccer players were recruited.
Final Sample: 35 participants completed the study after 4 participants from the Control Group (CG) dropped out due to external reasons.
Experimental Group (EG):
- $n = 20$
- Age: $10.5 \pm 0.30$ \text{ years}
- Body Mass: $37.94 \pm 6.00\,kg$
- Height: $1.42 \pm 0.05\,m$
- BMI: $18.05 \pm 2.11\,kg/m^2$
- Maturity Offset: $-2.58 \pm 0.15$
- Training Experience: $3.50 \pm 0.66$ \text{ years}
Control Group (CG):
- $n = 15$
- Age: $10.7 \pm 0.21$ \text{ years}
- Body Mass: $35.24 \pm 3.98\,kg$
- Height: $1.42 \pm 0.06\,m$
- BMI: $16.86 \pm 1.30\,kg/m^{-2}$
- Maturity Offset: $-2.48 \pm 0.10$
- Training Experience: $3.41 \pm 0.55$ \text{ years}
Ethical Compliance: Approved by the local University ethics committee; in accordance with the Declaration of Helsinki. Parents provided written informed consent.
Study Design: Random allocation; 12-week intervention; 2 sessions per week.

Methodological Procedures and Formulas

Familiarization Period: 4 weeks (two sessions per week) prior to training intervention.
Somatic Maturity Prediction: Calculated using the redeveloped equation from Moore et al. (2015):
- $\text{Maturity offset} = -7.999994 + (0.0036124 \times [\text{age} \times \text{height}])$
- $R^2 = 0.896$ , Standard error of estimated = $0.542$
Environmental Controls: Tests performed on artificial turf using soccer shoes. Time of day held constant (5 p.m. to 7 p.m.) for pre- and post-testing. Separate testing days had at least 48 hours between them.
Warm-up Protocol: 5 minutes of general jogging (forwards and backwards) and dynamic stretching (knee-to-chest, high kicks).
Equipment: Photocells timing system (Polifemo Radio, 0.125-ms resolution, Microgate) set at 0.70 m above ground.

Testing Protocols

5-m and 20-m Sprint Tests:
- Assessed first-step acceleration and linear speed.
- Three trials performed from a standing position; fastest trial recorded.
- Recovery: 3 minutes between trials.
Modified Illinois Change of Direction Test (MICODT):
- Assessed sprints, directional changes, turns, and slalom runs.
- Participants ran between specific points (A to B) around cones without touching them.
- Three trials with 3 minutes rest in-between.
Reactive Agility Test (RAT):
- Y-shaped agility test incorporating a live experimenter.
- Experimenter movements: Step forward with one foot/change direction with the other.
- Participants were instructed not to anticipate reactions.
- Four trials in randomized order; 2 minutes rest between trials.

Training Intervention Details

Duration: 12 weeks during the in-season (March–May); 24 total sessions.
Session Structure: 25 minutes total, performed at the start of a training session after an 8-minute warm-up.
EG Intervention (SAQ Training):
- Organized into two 10-minute phases with 5 minutes rest between phases.
- Exercise Work:Rest Ratio: 1:2.
- Weeks 1–2: Foot-working in hoops (split steps, line drills); sprints with few (1-3) directional changes ( $30^{\circ}$ and $45^{\circ}$ ).
- Weeks 3–5: Speed-ladder basic drills (one/two in the hole, skipping); sprints with 3–5 directional changes ( $30^{\circ}$ , $45^{\circ}$ , and $90^{\circ}$ ).
- Weeks 6–8: Speed-ladder advanced (carioca, cha-cha, cherry pickers); agility drills via command (color tag).
- Weeks 9–12: Ladder drills combined with visual stimuli agility; "mirror" drills with an opponent.
CG Intervention (Soccer-Specific):
- First phase: Technical circuits (ball carrying, passing, heading, dribbling).
- Second phase: Progressive evasion drills (1-on-1, 2-on-1, 2-on-2, 3-on-2).

Statistical Analysis

Reliability: Assessed via one-way intra-class correlation coefficients (ICC 1,k).
- 5-m Sprint: $ICC = 0.88$
- 20-m Sprint: $ICC = 0.92$
- MICODT: $ICC = 0.88$
- RAT: $ICC = 0.85$
Normality: Evaluated using the Shapiro-Wilks’ test.
Comparison: Unpaired t-tests for anthropometric/pre-training data; Two-way ANOVA (repeated measures on time) for changes.
Effect Size (ES) Classification (Hopkins et al., 2009):
- <0.2: Trivial
- $0.2–0.6$ : Small
- $0.6–1.2$ : Moderate
- $1.2–2.0$ : Large
- >2.0: Very large
Alpha Level: P < 0.05.

Results and Data Summary

5-m Sprint Test:
- EG: Improved from $1.53 \pm 0.08$ to $1.50 \pm 0.08\,s$ (2.0% change, $ES = 0.4$ ).
- CG: Changed from $1.49 \pm 0.07$ to $1.50 \pm 0.09\,s$ (0.7% change, $ES = 0.1$ ).
- Significant interaction found: $P = 0.044$ , $\eta^2 = 0.117$ .
Reactive Agility Test (RAT):
- EG: Improved from $2.85 \pm 0.15$ to $2.73 \pm 0.15\,s$ (4.2% change, $ES = 0.8$ ).
- CG: Changed from $2.78 \pm 0.19$ to $2.75 \pm 0.19\,s$ (1.1% change, $ES = 0.2$ ).
- Significant interaction found: $P = 0.002$ , $\eta^2 = 0.248$ .
20-m Sprint Test:
- Significant within-subjects improvement for both groups: $P = 0.002$ , $\eta^2 = 0.256$ .
- EG: $4.27 \rightarrow 4.16\,s$ ( $ES = 0.4$ ).
- CG: $4.11 \rightarrow 4.05\,s$ ( $ES = 0.3$ ).
Change of Direction (MICODT):
- Remained unchanged for both groups ( $P = 0.245$ , $\eta^2 = 0.041$ ).

Discussion and Implications

Acceleration (5-m): Significant improvement likely due to specificity of foot-working drills. Short contact times elicit higher force production at faster rates, improving intra- and intermuscular coordination of the stretch-shortening cycle (SSC).
Reactive Agility (RAT): This was the first study to assess SAQ effects on reactive agility in preadolescents. Moderate improvements in EG suggest that cognitive drills in response to non-sport specific stimuli effectively train reaction skills in middle childhood (ages 7–14).
CODS Stability: The lack of improvement in CODS (MICODT) is likely because the peak rate of development for change-of-direction ability typically occurs at puberty ( $13–14$ \text{ years old}). Prepubescent athletes may have limited neuromuscular adaptability for these specific patterns.
20-m Sprint Results: Small improvements in both groups suggest that 20-m speed gains were likely due to natural nervous system maturation during the sampling stage rather than the training intervention itself.
Limitations: The RAT evaluation focused on total time rather than isolating decision time. Future studies should use high-speed video to separate cognitive processing time from physical execution time.

Conclusions

Effectiveness: SAQ training is more effective at improving initial acceleration ( $0–5\,m$ ) and reactive agility (open skill) than traditional soccer training in preadolescent players.
Inadequate Effects: SAQ training did not significantly impact top speed ( $20\,m$ ) or planned change of direction (closed skill) in this specific age group.
Practical Application: Soccer coaches should integrate organized SAQ drills to successfully improve the agility profile of players during the middle childhood phase.