Participants & Procedures

Participants

• 12 healthy female soccer athletes, ages 18-25 years, will participate in the study (recruitment still in progress).

What is a "healthy female soccer athlete"?

• Current participation in a recreational or competitive soccer league  OR
• Has participated in a league requiring activity for at least 30 minutes on three out of seven days of the week in the previous 24 months

Exclusion Criteria

• No lower extremity injury in the last six months
• No previous knee surgery requiring reconstruction
• No less than five years of experience playing soccer
• No neurological condition impairing the ability to jump or head a soccer ball
• Not currently taking anti-vertigo medications

A 3 minute warm-up at 70 RPM was performed on a Cycle Ergometer prior to the Vertec max jumps.

Procedures

1. Informed consent, health history questionnaire, and Covid-19 screening form are completed and signed digitally 
2. 3 maximal jumps using a Vertec system are performed to determine the height of the soccer ball (50% of max)
3. Anthropometric measures are taken & subject is prepped with retro-reflective markers and electromyography (EMG) sensors
4. A modified dynamic warm-up is performed
5. Two jumps are explained and completed:

31cm box is positioned so that participants may land with one foot fully on each force plate (signifies a good trial). 

→ Drop Vertical Jump (DVJ)

• Subject steps off of a 31 cm box and upon landing, immediately jumps with maximal effort before landing again

The hanging soccer ball apparatus was set at 50% of the participant's maximum jump height and situated comfortably in front of participants during SSVJ trials.

→ Soccer Specific Vertical Jump (SSVJ)

• Subject steps off of a 31 cm box and upon landing, immediately jumps to head the hanging soccer ball before landing again

*** 3-4 good trials of each jump are collected

The Cybex dynamometer being used to record torque values during knee extension (3 reps of 3 seconds, 60 seconds of rest).

6. Maximum voluntary isometric contractions (MVICs) are performed for knee extension and knee flexion. A Cybex dynamometer is used to record the torque of each movement.

The handheld dynamometer being used to collect torque values for ankle dorsiflexion (3 reps of 3 seconds, 60 seconds of rest).

7. MVICs are performed for ankle dorsiflexion and plantarflexion, hip extension, and hip abduction. A handheld dynamometer is used to record the torque of each movement.