A note from Kristy Arbogast, PhD, CIRP@CHOP co-director: Today we are pleased to welcome a guest blog post from Jaclyn Caccese, PhD, a post-doctoral research fellow in the Department of Kinesiology at Temple University. Dr. Caccese’s research focuses on sensorimotor integration during standing and walking following sub-concussive head impacts in soccer. Her previous work has identified determinants of head acceleration during soccer heading. I asked Dr. Caccese to share some insights from her research for our blog audience on current initiatives in the soccer world on the appropriateness of heading for youth players.
Following the settlement of a class-action lawsuit in November 2015, U.S. Soccer instituted an initiative to improve concussion awareness and management. As part of the initiative, youth players under 10 years of age are not allowed to head the ball and those 11-13 years of age are limited to 15-20 headers per week. These guidelines were implemented to reduce overall head impact exposure and keep athletes out of situations which make them vulnerable to head injury, such as unintentional head impacts with other players that may occur when attempting a header. However, there is little scientific evidence to support when an athlete is ready to begin soccer heading; a combination of physical maturity and stage of brain development is likely a more appropriate benchmark than age alone. However, until high-quality scientific research can determine specific criteria for when an athlete should begin soccer heading, a conservative approach such as the current age restrictions may be useful.
The State of the Science
While soccer heading research is still in its infancy, current research may help increase our understanding regarding determinants of head acceleration (i.e., how fast the head is speeding up or slowing down), a common measure of head impact severity, and outcomes from acute heading drills. In my dissertation, I looked at head accelerations sustained during soccer heading – across ages and for both males and females – and related acceleration to clinical markers of potential injury. Here’s what I learned:
One of Dr. Caccese's research subjects
- Under the controlled laboratory conditions I studied, there was no significant difference in head acceleration among youth (12-14 years old), high school, and collegiate soccer players. This suggests that with proper training, athletes 12 years of age and older may be ready to begin soccer heading.
- Female soccer players, regardless of age, sustained higher head accelerations than male soccer players. The observed sex difference is a result of lower head mass, neck girth, and neck strength among female athletes. Because strength is a modifiable factor, perhaps future research will establish neck strengthening protocols that can be used to minimize head acceleration, particularly for female athletes.
- There are subtle, transient effects in cognition, postural control, and blood biomarkers immediately following soccer heading that dissipate within 24 hours. It is still unclear is if these effects are clinically meaningful over a season– or a career– of play.
Although there are incidents of long-term neurological impairments in soccer players, it is unclear if these are the result of repeated head impacts or undiagnosed/unrecognized concussions. U.S. Soccer has taken steps to improve concussion education and allow those suspected of having a concussion to be removed from play for evaluation without penalty. This is an important rule change, from which many soccer players will benefit.
What Parents Need to Know
Here are my recommendations that can be shared with parents and caregivers:
- Know your child. If your child does not feel comfortable heading the soccer ball, then he/she should probably not be doing it. Soccer heading should be an active movement; your child should be trying to hit the ball, not standing around waiting for it to hit him/her.
- Technique, technique, technique. Before allowing your child to begin heading a soccer ball, make sure that they can do so safely. Practicing with a light-weight ball, such as a Nerf ball, allows young athletes to work on technique before being exposed to the higher forces associated with a heavier ball.
- Be aware of all the signs and symptoms of concussion. There is no evidence that a concussion, if managed properly by a medical professional, will result in long-term neurological deficits. If you suspect a concussion, your child should be immediately removed from play and you should seek evaluation from a health care professional. Learn more on CHOP’s Concussion Care for Kids website.
What Comes Next?
Walking is an activity of daily living, and poor balance control during walking may have negative implications on the soccer field (e.g., increased risk of lower extremity injury). At Temple, our future research will investigate how soccer heading affects balance control during walking through applying sensory perturbations. By probing these mechanisms that are critical for normal gait, we can use these findings to guide the development of gait interventions to be performed in the clinic and during daily life activities.
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