Effects of a 6-Month Gymnastics Program on Somatotype and Motor Performance in Children Across Age Groups

The study design for the present investigation was prospective, controlled, and observational with a duration of 6 months. The repeated measures design approach has been used to assess the neuromuscular and morphological adaptations (Pre-test vs. Post-test) for the gymnastics and inactive groups. The intervention and observation period for the study was 2 days x 24 weeks.

To ensure high internal validity and to minimize the effects of circadian rhythm changes, all pre- and post-test assessments were conducted during the morning hours, between 09:00 and 11:30 AM, under similar environmental conditions (temperature and humidity). Prior to the pre-test, standardized pre-test procedures were clearly explained to the participants and their parents. Children were instructed to adhere to their routine sleeping habits (minimum 8 hours of sleep) and abstain from any strenuous physical activity and sports for at least 24 hours prior to the pre- and post-test assessments.

With regard to the standardized nutritional conditions, the participants were instructed to adhere to their routine diet but abstain from heavy meals for at least 2 hours prior to the pre- and post-test assessments. Participants were allowed to drink water ad libitum up to 30 minutes prior to the assessments.

On the assessment days, a logical and non-fatiguing sequence of the pre- and post-test assessments was strictly followed. Non-invasive anthropometric assessments such as stature, body mass, skinfolds, girths, and breadths were conducted for all the participants, while they were in a rested and non-sweated condition. After the anthropometric assessments, the participants were administered a standardized 10-minute dynamic warm-up procedure by a certified strength and conditioning specialist. Subsequently, the motor performance tests were conducted. To prevent the participants from fatigue, the physical tests were conducted from the least to the most fatiguing, from flexibility to muscular endurance and sprint capacity, with strict adherence to the intervening time of 3-5 minutes between the assessments

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• Gymnastic Exercise (Other): Gymnastic Training for six month

Primary outcomes

• Circumferences (Girths) Measurements [6 month]: Girth measurements were taken to the nearest 0.1 cm using a flexible, non-stretchable anthropometric tape measure (Lufkin W606PM, Apex Tool Group). The measured girths included the head, neck, shoulder, chest, waist, hip, relaxed arm, forearm, thigh, maximum calf, and ankle circumferences. Care was taken to ensure the tape measure was at a right angle to the long axis of the body segment and did not compress the subcutaneous tissue.
• Skinfold Thickness Measurements [6 month]: Skinfold thicknesses were measured to the nearest 0.1 mm using a Harpenden skinfold caliper (Baty International, West Sussex, UK). Measurements were taken in duplicate at nine standardized sites: triceps, subscapular, biceps, chest, axillary, abdominal, suprailiac, anterior thigh, and medial calf. If the difference between the first two measurements exceeded 5%, a third measurement was taken, and the median value was recorded for analysis. Furthermore, to obtain a comprehensive and robust quantification of total subcutaneous adiposity, the sum of all nine measured skinfolds (Σ9SF) was calculated. In pediatric kinanthropometry, the absolute sum of multiple skinfold sites is widely recognized as a highly reliable proxy for total body fatness, as it circumvents the inherent biological maturation errors and prediction biases associated with population-specific body density and body fat percentage equations.
• Waist-to-Height Ratio [Six Month]: Calculated by dividing waist circumference (cm) by standing height (cm). This ratio serves as a highly validated, age-independent proxy for central adiposity and health risk in pediatric populations.
• Segment Lengths and Bone Breadths Measurements [Six Month]: Segment lengths (arm span, total arm, forearm, total leg, thigh, tibia, and foot lengths) were measured using a segmometer and anthropometric tape to the nearest 0.1 cm. Skeletal breadths were measured to the nearest 0.1 cm using a sliding spreading caliper. The breadth measurements included the shoulder, biacromial, biiliac, bitrochanteric, knee (biepicondylar femur), elbow (biepicondylar humerus), and wrist.
• Body Fat (BF) and Fat-Free Mass [six month]: Relative body fat percentage (BF%) was estimated using the pediatric-specific skinfold equations developed by Slaughter et al. Specifically, this calculation utilized the sum of the triceps and subscapular skinfold thicknesses, adjusted for biological sex and maturation, which is considered the gold standard for clinical field assessments in youth. Subsequently, total body fat mass was determined, and absolute Fat-Free Mass (FFM in kg) was calculated by subtracting this estimated fat mass from the total body mass.
• Skeletal Muscle Mass [six month]: Total skeletal muscle mass (kg) was estimated by employing validated anthropometric prediction models for children and adolescents, which account for standing height as well as corrected limb girths (i.e., thigh, calf, and arm circumferences that have been corrected for their respective overlying subcutaneous adipose tissue thicknesses).
• Arm Muscle Area [six month]: AMA was calculated to estimate regional upper-body muscularity and protein reserves. AMA (cm²) was derived from relaxed arm girth (cm) and triceps skinfold thickness (cm) using the standard anthropometric equation
• Somatotype [six month]: The anthropometric somatotype components, namely endomorphy, mesomorphy, and ectomorphy, were calculated according to the Heath-Carter method \[17, 24\]. Endomorphy was estimated based on the height-adjusted sum of three skinfold thicknesses: triceps, subscapular, and suprailiac.
• Motor Performance Tests [six month]: Flexibility (Sit and Reach Test): Lower-Body Explosive Power: Muscular Endurance: Speed (20-m Sprint):
• Body Composition [6 months]: Endomorphy was estimated based on the height-adjusted sum of three skinfold thicknesses: triceps, subscapular, and suprailiac. Mesomorphy was determined using humerus (elbow) breadth, femur (knee) breadth, height, and corrected limb girths. Corrected arm girth (CAG) and corrected calf girth (CCG) were adjusted for the corresponding skinfold thicknesses. Ectomorphy was derived from the Height-Weight Ratio (HWR), which was calculated as height divided by the cube root of body mass.
• Weight [6 Month]: Participants were assessed barefoot and wearing minimal clothing. Participants' body weight was measured using a Seca (Seca GmbH, Hamburg, Germany) scale with an accuracy of 0.1 kg.
• Height [6 month]: Participants' height was measured using a Seca (Seca GmbH, Hamburg, Germany) stadiometer with an accuracy of 0.1 cm.
• Body Mass Index [6 month]: Participants' body mass indices (BMI) were calculated using the weight/height² formula (kg/m² ).

Sex: All, ages: 4 Years to 12 Years, accepts healthy volunteers

Inclusion Criteria:

* For Experimental Group: Active and continuous participation in a gymnastics program during the entire 6-month period.
* Inactive control group : comprised participants who did not practice any form of sports, athletics, and physical training outside their usual physical education classes at school.

Exclusion Criteria:

* the presence of any chronic metabolic, cardiovascular, and endocrine disorders;
* a history of severe musculoskeletal injuries and orthopedic surgeries within the past year;
* the use of medications known to have a significant impact on body composition and physical performance; and
* an attendance rate of less than 85% for the gymnastics sessions (only for the intervention group).