Research: ‘Effects of Strength Training on Cognitive Function, Brain-Derived Neurotrophic Factor and Insulin-Like Growth Factor 1 in Highly-Trained Young Female Soccer Players’
Author: Mariem Bousselmi et al
Journal: Sports Medicine – Open (2026)

In modern women’s soccer, heavy demands are placed on both physical fitness and cognitive skills, such as quick decision-making on the pitch. This study examined the effects of a 12-week (in-season) strength training program on highly-trained young female soccer players around 15 years of age (national U15 level). The players were divided into two groups:

• The strength training group performed two weekly strength training sessions (upper and lower body) and three regular soccer training sessions.
• The control group exclusively performed five weekly soccer training sessions.

The Strength Training Intervention The 12-week program was structured into three 4-week training cycles.

• Schedule: During the first three weeks of each cycle, the strength training group performed two 90-minute strength sessions and three regular soccer sessions per week. In the fourth week, they performed no strength training and only completed five soccer sessions.
• Exercises: The sessions targeted the full body and included the leg press, hip thrust, squat, bench press, lat pull-down, and calf raises.
• Progressive Overload: The intensity increased over the three cycles. Cycle 1 consisted of 3 sets of 15 repetitions at 40-60% of the 1-Repetition Maximum (1-RM). Cycle 2 progressed to 3 sets of 12, 10, and 8 repetitions at 60-75% of 1-RM. Cycle 3 further intensified to 3 sets of 10, 8, and 6 repetitions, reaching up to 85% of 1-RM.

Testing Procedures To evaluate the effects of the intervention, tests were conducted before (pre) and after (post) the 12-week period.

• Anthropometrics and Body Composition: Researchers measured body mass with a scale, height with a stadiometer, and calculated the Body Mass Index (BMI). Body fat percentage was calculated using a skinfold caliper.
  
• Muscle Strength: Maximal dynamic strength was determined via 1-RM tests on machine-based exercises: the leg press, bench press, and lat pull-down.
  
• Soccer-Specific Skills: Technical performance was measured using the Loughborough Soccer Passing Test (LSPT). In this test, players were required to complete 16 passes (both short and long) to colored targets on benches as quickly as possible. Penalty seconds were added to their total time for mistakes, such as missing the target or hitting a cone.
  
• Cognitive Function: Executive function was assessed using the Stroop test, which required verbal responses across three 45-second tasks. Players had to read words out loud (Stroop Word), identify colors (Stroop Color), and state the ink color of a conflictingly written word (Stroop Word-Color).
  
• Neurological Markers: To check for markers of neuroplasticity, fasting venous blood samples were drawn to measure the serum concentrations of basal Brain-Derived Neurotrophic Factor (BDNF) and Insulin-Like Growth Factor 1 (IGF-1).

Main Findings

• Physical and Soccer-Specific Performance: The strength training led to a significant increase in maximal muscle strength, measured via the 1-RM leg press, bench press, and lat pull-down. Technical performance in the LSPT also improved significantly. This was mainly because the players who performed strength training received significantly fewer penalty seconds for errors (-65.4% compared to the control group).
  
• Body Composition: At the end of the 12 weeks, body fat percentage had decreased in the strength training group. Additionally, a significant increase in total body mass was observed in this group.
  
• Cognitive Function: Players who performed strength training performed significantly better on the Stroop test. This test measures executive functions such as selective attention, cognitive flexibility, and inhibition (suppressing automatic responses). This indicates improved information processing and decision-making.
  
• Neurological Biomarkers: Despite the cognitive and physical progress, no significant changes were observed in the blood for resting concentrations of BDNF and IGF-1. These are proteins that play a key role in the neuroplasticity of the brain. The researchers suspect that fit, frequently training youth athletes have already reached an optimal, stabilized baseline level for these substances.

Conclusion for Practice Adding two strength training sessions per week to the regular in-season program not only strengthens the bodies and muscle power of young female players but also enhances their technical (passing) precision and their ability to execute cognitive tasks faster under pressure. Therefore, the researchers strongly recommend that coaches implement strength training for young female players.

Additional insights from international research (2021–2026)

In the broader international field, additional findings on this topic have emerged over the past five years:

• The link between strength training, cognition, and injury prevention (ACL): There has recently been much focus on the cognitive component in non-contact injuries, such as anterior cruciate ligament (ACL) tears – an injury relatively common among female soccer players. Research indicates that a lack of situational awareness and a delayed reaction to unexpected stimuli on the pitch contribute to these injuries. Strength training appears to condition the nervous system in such a way that players not only land with more stability but also react faster neurologically (psychomotor speed) to make corrective movements.
  
• Agility and Perception (Reactive Agility): While pure sprint speed often improves around puberty due to hormonal and bone structure changes, reactive agility appears highly dependent on training. Female players develop so-called ‘game intelligence’ much faster when physical (resistance) training is paired with environmental scanning (e.g., passing balls in response to external visual cues). Dual-task training has now become the standard in elite sports academies.
  
• Neurological maturation is paramount: In the early teenage years, the primary benefit of strength training lies in neural adaptation – meaning the brain learns to recruit existing motor units in the muscles more efficiently. This is likely also the reason why technical ball control and accuracy in studies like Bousselmi et al.’s improve so exponentially after the nervous system is ‘stimulated’ through strength training.

This summary and the accompanying insights were generated with the assistance of Artificial Intelligence (AI) to synthesize scientific research.