Friday, November 28, 2008

Cutting-Edge Research: Do Soccer Headgears Protect Both Men and Women Against Injury?

Soccer headgears such as the Full 90 and Head Blast Soccer Band are becoming increasingly popular as a tool to protect against head injuries. However, a recent study completed at Temple, Towson and George Mason Universities suggests that they do not offer protection as much protection as advertised, especially in women. Head acceleration (a measure of the rate of head “recoil”) and the head injury criterion (HIC) during standing front headers, were actually increased in women who were wearing headgear compared to wearing no protection. In men, these values were slightly reduced. It appears that the lack of protection in the women is related to the lack of neck muscle strength. The authors of the study suggest that soccer headgear may not be an appropriate protective device for all players.

The study, one of the first of its kind, is published in the November issue of the Journal of Athletic Training. Groups of men and women players (~20 years of age) performed standing front headers using a ball delivered by a Juggs ball machine (22mph or 9.83 m/s). Headers were performed without any headgear and while wearing the Full 90 and Head Blast Soccer Band. The researchers measured neck strength, head acceleration (a measure of the rate of “recoil”) and the head injury criterion (a calculated value that assesses injury risk potential).

Neck strength in men (neck flexion and extension) was nearly twice that of women. This resulted in men having slightly lower acceleration and HIC values (~10%) when heading the ball without wearing headgear. When wearing either headgear, however, women experienced considerably greater head movement than men. Acceleration was 32% greater and HIC was 44% greater. In women, wearing headgear actually INCREASED both values compared to wearing no headgear. This suggests that women may be at greater risk of injury when heading the ball with a headgear than without.

Interestingly, the amount of head acceleration and HIC while wearing the headgear was related to strength of the neck muscles. The weaker the neck muscles, the greater the extent of head movement and the greater the risk of head injury. This suggests that soccer headgears may be unwise for players with weak neck muscles.

The investigators point out that one explanation of their findings is that women may perform more forceful headers when wearing headgear. This could increase both acceleration and HIC. They may feel that the headgear offers more protection and have a sense of safety is giving a more forceful effort. The relationship between neck strength and head acceleration supports this idea. Neck strength does not influence how forceful a header is performed (that is determined, in large part by core strength). Neck strength does, however, stabilize the neck and help reduce rapid head movements. When weaker players attempt to head the ball more forcefully when wearing the headgear, their lack of neck strength results in the head recoiling more rapidly and raises the risk of injury.

The authors of the study suggest that trainers be cautioned when advising players on the use of headgear (especially for women). Given the results of this study, it seems that soccer headgear may offer only a false sense of security rather than true protection when heading the ball. The authors also emphasize the need for more research, especially in youth players. Soccer headgears are often recommended for these players and advertising campaigns specifically target younger players. It remains to be seen if they offer the level of protection as advertised or if they increase risk as seen in adult women.

Reference:

Tierney RT, Higgins M, Caswell SV, Brady J, McHardy K, Driban JB, Darvish K (2008) Sex differences in head acceleration during heading while wearing soccer headgear. Journal of Athletic Training, 43: 578-584.