Recent crosse designs increase ball velocity: Implications for injury in women's lacrosse

Head injury potential and the effectiveness of headgear in women's lacrosse

Over the past 10 years, lacrosse has grown increasingly popular, making it one of the fastest growing team sports in the country. Similar to other sporting activities, head injuries in lacrosse can and do occur, and the number of lacrosse-related head injuries has increased in recent years. In women's lacrosse, protective headgear is not required, but U.S. Lacrosse and the American Society for Testing and Materials are currently working to develop a headgear standard for the women's game. In the interim, some female lacrosse programs and individual players are wearing soft headgear during play. The effectiveness of this headgear is unknown. Testing was conducted to better understand the material properties of various types of headgear that may be used in lacrosse and the effect of this headgear on head impact response and head injury potential. For the evaluation of head impact response, an instrumented Hybrid III anthropomorphic test device (ATD) was impacted on the side of the head with lacrosse balls and the front and side of the head with a lacrosse stick. The linear and rotational impact response of the head and corresponding acceleration-based injury metrics are reported. Testing was then repeated with the ATD wearing different types of headgear. Tested headgear included a men's lacrosse helmet and two brands of commercially-available soft headgear. For the higher velocity ball impacts, there was no statistically-significant difference in the measured linear and rotational response of the head for the no headgear and soft headgear test conditions. For the lower velocity ball impacts, there was a small, yet statistically-significant, reduction in head linear acceleration for one of the soft headgears tested in comparison to the no headgear test condition, but there was not a statistically-significant difference in the rotational impact response with this headgear. These results indicate that the soft headgear would not be effective in reducing head injury potential during higher velocity ball impacts, such as ball speeds associated with shooting in women's lacrosse. The men's lacrosse helmet reduced both the linear and rotational response of the head for the higher and lower velocity ball impacts. Material testing showed that the padding in the hard helmet exhibited larger strain energy than the padding within the soft headgears when tested in compression. These results correlate with the larger reductions in head accelerations during ball impacts by the hard helmet. For the stick impacts, there were no statistically-significant differences in the lateral impact response of the head for the helmeted and soft headgear test conditions in comparison to the no headgear test condition, but there were statistically-significant, albeit small, differences in the frontal impact response of the head. The similar impact responses of the head during the stick impacts with and without headgear can be attributed to the relatively low severity of these impacts and the characteristics of the impactor.

Lower Extremity Muscle Activity During a Women's Overhand Lacrosse Shot

The purpose of this study was to describe lower extremity muscle activity during the lacrosse shot. Participants (n=5 females, age 22±2 years, body height 162.6±15.2 cm, body mass 63.7±23.6 kg) were free from injury and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG) leads to measure muscle activity of the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (GA). Participants completed five trials of a warm-up speed shot (Slow) and a game speed shot (Fast). Video analysis was used to identify the discrete events defining specific movement phases. Full-wave rectified data were averaged per muscle per phase (Crank Back Minor, Crank Back Major, Stick Acceleration, Stick Deceleration). Average EMG per muscle was analyzed using a 4 (Phase) × 2 (Speed) ANOVA. BF was greater during Fast vs. Slow for all phases (p<0.05), while TA was not influenced by either Phase or Speed (p>0.05). RF and GA were each influenced by the interaction of Phase and Speed (p<0.05) with GA being greater during Fast vs. Slow shots during all phases and RF greater during Crank Back Minor and Major as well as Stick Deceleration (p<0.05) but only tended to be greater during Stick Acceleration (p=0.076) for Fast vs. Slow. The greater muscle activity (BF, RF, GA) during Fast vs. Slow shots may have been related to a faster approach speed and/or need to create a stiff lower extremity to allow for faster upper extremity movements.

Modeling the Lacrosse Stick as a Rigid Body Underestimates Shot Ball Speeds

In the last decade, dramatic changes in lacrosse stick design are believed to be associated with changes in the play of the game; however, there is a limited understanding of how the lacrosse stick propels the ball. We predicted that the lacrosse stick would perform as a passive extension of the player’s hand and hypothesized that ball shot speed would be equal to the speed at the tip of the stick. Ball and shot kinematics of 16 male and 16 female lacrosse players using four various stick models were tracked at 250 Hz. The speed of the ball was compared with the speed at the tip of the stick, calculated by assuming the stick behaved as a rigid body. Ball shot speeds with men’s sticks were on average 3.5 m/s (7.8 mph) faster than the calculated speed at the stick tip, and ball shot speeds with women’s sticks were on average 0.7 m/s (1.5 mph) faster than stick tip speed. Some lacrosse stick models can shoot the ball significantly faster than predicted when considering the stick as a rigid, passive extension of the player’s hands.