With the rise of soccer's global prominence, injury risks among players remain a concern. Deceleration and change of direction maneuvers are frequently employed as an evasive strategy during games. However, they often contribute to higher risk of non-contact anterior cruciate ligament (ACL) injuries. Sidestep cutting involves planting with one foot and pushing off in the opposite direction. Improper movement patterns may increase loads on the planted leg leading to injuries. Injury prevention initiatives such as the FIFA11+ have been introduced to reduce injury rates, but it is unclear whether these programs can correct movement patterns during cutting. Moreover, the length of these programs (often lasting 20 minutes) can reduce adherence and hinder their practical implementation in the real-world. This results in alternative programs like the Brazilian warm-up to be used instead.

In addition, females are significantly more at-risk of ACL injuries than males. This is often attributed to differences in movement pattern and anatomy. Variations in foot anatomy can affect how players interact with footwear, which may in turn, influence cutting patterns. Yet, soccer footwear is typically designed using a male foot template (i.e. last), resulting in a one-size for all approach for female athletes.

In order to address current limitations, this study aims to estimate the effect of a shortened FIFA11+ and sex-specific footwear on cutting kinematics in youth soccer players. This will be done in two parts, where part 1 examines two warm-up programs, and part 2 examines two types of footwear. Ethics approval and informed participants and parental consent as well as assent have been obtained.

For part 1 of the study, 64 healthy soccer players will be recruited from Soccer Montréal (formerly known as Association Régionale de Soccer Concordia (ARSC)) sport study program. Soccer Montréal provides soccer sport study programs to high schools for high performance soccer players. Soccer Montréal conducts soccer training with pre-established cohorts separated by sex and age. Two male and 2 female cohorts will be allocated to either the intervention or control group. Male cohorts of similar age groups will be selected, and the entire cohort will be randomly allocated using a computer. The female cohorts have different age groups, and thus allocation to intervention or control will be divided within each cohort following a quasi-randomized fashion. During the testing, participants are required to perform an unanticipated sidestep maneuver at 45 (±10) degrees on artificial turf. Data will be collected with markerless motion capture systems. A total of 7 trials will be captured in each direction, only 5 out of 7 will be analyzed.

For part 2 of the study, female participants from part 1 (32 females) will test two types of footwear: Female-specific and unisex soccer cleats. Testing will be done at one time point. Female-specific cleats are provided from IDA sports, specifically the IDA centra FG/AG model. Unisex cleats are the Nike Tiempo Legend 10 Academy. Proper fit of shoe sizes will be examined manually by the research team prior to testing. Kinematic data will be collected using the same unanticipated sidestep task as part 1. Additional testing will include a slalom course to examine functional traction of the shoes. Participants will complete an online comfort survey, following the slalom course, once for each shoe. A subset of female participants will also complete a sidestep cutting task with wireless insoles to measure pressure data.

Findings of this study will advance knowledge of ACL injury mechanism during cutting tasks, aid in the design of more practical injury prevention programs and guide the development of female-specific footwear.