Effects of 8-Week CrossFit-Based Concurrent Training on Fitness, Body Composition, and Psychological Outcomes in Schoolchildren

Condition(s) studied

Investigational drug(s) / intervention(s)

CrossFit training: The experimental arm will receive an 8-week concurrent training intervention based on a CrossFit program adapted for children, with a frequency of two 50-minute sessions per week. Each session will be structured into a warm-up (mobility exercises and games), strength training (technical and functional exercises), metabolic conditioning (METCON), and a cool-down phase. The program will be supervised by qualified professionals to ensure safety and proper execution of the exercises.

Study summary

This study examines the effects of an 8-week CrossFit-based concurrent training program in boys and girls aged 7 to 11 years, comparing an experimental group (n=15) with a control group (n=15). The aim is to assess changes in strength, cardiorespiratory fitness, body composition, and psychological variables such as anxiety, stress, and self-esteem, using field-based physical tests (CMJ, Course Navette, handgrip strength, etc.) and validated questionnaires. The study follows a randomized controlled trial design with pre- and post-intervention assessments. The experimental group will complete two weekly CrossFit sessions adapted for children, while the control group will maintain their usual routine without structured physical training. The hypothesis states that the intervention will significantly improve both physical performance and psychological well-being in the experimental group compared to the control group.

Eligibility

Primary outcome measure(s)

• Countermovement Jump Test (CMJ) - Explosive Strength Test — Week 1 (Day 1), Week 8 (Day 16)
  The countermovement jump (CMJ), is used to assess explosive strength of the lower limbs. In this test, participants begin in an upright standing position with their hands placed on their hips to avoid arm swing contribution. They are instructed to perform a maximal vertical jump following a rapid downward countermovement, descending to approximately 90° of knee flexion, and then immediately jumping as high as possible.
• Standing Long Jump — Week 1 (Day 1), Week 8 (Day 16)
  This test consists of performing a horizontal jump using both feet simultaneously, starting from the same level. A preliminary jump is not allowed. The maximum horizontal distance achieved is recorded, measuring from the starting line to the rearmost point of the shoe closest to that line. Upon landing, the participant must maintain balance and remain stationary.
• Medicine Ball Throw Test — Week 1 (Day 1), Week 8 (Day 16)
  The medicine ball throw test (2 kg) is performed from an upright standing position, holding the ball with both hands above the head. Participants are required to throw the ball as far as possible by performing a flexion-extension movement of the legs, with or without trunk extension.
• 20 m Shuttle Run Test (Course-Navette) — Week 1 (Day 1), Week 8 (Day 16)
  In the 20 m shuttle run test, participants run back and forth between two lines set 20 m apart, with progressively increasing speed. The initial running speed is 8.5 km/h and increases by 0.5 km/h every minute. Each increase in speed corresponds to a new level.
• Plank Hold Time — Week 1 (Day 1), Week 8 (Day 16)
  The plank protocol requires participants to maintain a static prone position, with only the forearms and toes in contact with the ground. Proper form requires feet together with toes pointing downward, elbows positioned under the shoulders at forearm width, and hands clasped together on the floor.
• Burpess — Week 1 (Day 1), Week 8 (Day 16)
  To perform a burpee, participants begin with feet shoulder-width apart and lower into a squat by bending the knees. They then place their palms on the floor and jump back into a plank position with arms extended, ensuring hands face forward, feet rest on the toes, and the back remains straight. Next, they perform a push-up by bending the elbows and returning to the plank position. Then, they jump forward into a squat position, keeping hands on the ground, hips lowered, thighs parallel to the floor, and knees positioned between the elbows. Finally, they jump vertically from the squat position, extending the arms overhead during the jump.
• Step Test — Week 1 (Day 1), Week 8 (Day 16)
  This test consists of stepping up and down on a platform approximately 30 cm in height, maintaining a constant speed and rhythm.
• State-Trait Anxiety Inventory for Children — Week 1 (Day 1), Week 8 (Day 16)
  State-Trait Anxiety Inventory for Children is a psychological instrument designed to measure two dimensions of anxiety in children: state anxiety, referring to temporary or situational anxiety, and trait anxiety, which assesses the general tendency to experience anxiety.
• Children's Daily Stress Inventory — Week 1 (Day 1), Week 8 (Day 16)
  This test aims to assess daily stress in children by evaluating how common experiences, such as school, family, and social issues, contribute to stress levels.
• Rosenberg Self-Esteem Scale — Week 1 (Day 1), Week 8 (Day 16)
  The Rosenberg Self-Esteem Scale assesses an individual's self-worth through a series of statements reflecting overall self-evaluation.

Trial sites (1)

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