Prepare for the Unpredictable: Sex differences in neck strength and the association with head acceleration in predictable and unpredictable perturbations in football
A summary of the research:
This research looked into how male and female football players respond to impacts on their head and neck, especially focusing on differences in neck strength and how the head moves during hits. The study found that while both male and female players experienced more head movement (called "head acceleration") when they couldn't anticipate an impact, female players showed significantly greater head acceleration and displacement, particularly in these unpredictable situations. Males, on the other hand, were generally stronger in all neck directions and could develop force faster, especially in neck extension, compared to females. There was no significant difference found in how quickly their muscles began to produce force after a signal (called "electromechanical delay" or EMD) between the sexes.
The study concluded that these differences in how quickly force can be generated (Rate of Force Development, or RFD) are important, as slower RFD was linked to higher head acceleration in females. This suggests that improving the speed at which neck muscles can generate force, especially in the early stages of a contraction (0-150 milliseconds), could help reduce head acceleration and prevent injuries in female football players. These findings highlight a critical need for training strategies specifically designed for female athletes to build neck strength and RFD, making the sport safer for them.
Here are three practical and actionable takeaways for coaches and administrators in women's soccer:
Prioritize Neck Strengthening, Especially Extension, for Female Players: The research consistently shows that females tend to have weaker necks than males and a higher ratio of head mass to neck muscle size, making neck strengthening even more vital for them. Specifically, focus on strengthening the neck in the extension (backward) direction, as males showed significantly greater strength in this area, which helps counteract impact forces during actions like heading and improves head stability. Increasing neck extension strength has been linked to a reduction in concussion rates in male athletes, suggesting similar protective benefits for females.
Emphasize Training for Rapid Force Development (RFD) in Neck Muscles: Since slower RFD was associated with higher head acceleration, particularly in female players, coaches should incorporate training that improves the speed at which neck muscles can generate force. This is crucial because many head and neck injuries in football come from unpredictable impacts (like collisions), where athletes have very little time to prepare their muscles. Training methods such as plyometric exercises and perturbation training can help athletes' necks react faster and generate force quickly, enhancing their ability to mitigate sudden impacts.
Implement Sex-Specific and Position-Specific Heading and Neck Strength Training Programs: Male players tend to head the ball more frequently, which might unintentionally act as a training stimulus for neck strength and RFD. However, female players often receive less coaching on proper heading technique. Therefore, coaches should proactively develop and implement structured programs that teach proper heading technique and include neck strengthening specifically for female athletes. Furthermore, consider the demands of different positions (e.g., center backs needing more neck extension strength for heading, goalkeepers requiring more balanced strength for multi-directional impacts) to tailor training programs for optimal injury prevention and performance.
Author: Jessica Fuller
You can read the entire master’s thesis here.
