The Effect of External and Combined Focus Instructions on Lower Extremity and Trunk Kinetic and Kinematic Parameters During Landing in Young Female Athletes With Asymptomatic Dynamic Knee Valgus - A Randomized Controlled Trial
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- Enrollment
- 18
- Locations
- 1
- Primary Endpoint
- 3D motion analyses
Study Overview
Brief Summary
Female athletes are at higher risk of knee injuries, particularly non-contact anterior cruciate ligament (ACL) injuries, often caused by dynamic knee valgus during landing. Proper landing techniques and neuromuscular training are crucial for injury prevention. Attentional focus strategies, such as external focus (EF) and internal focus (IF), can influence movement patterns, muscle activation, and skill transfer during landing tasks. EF generally promotes safer and more controlled landings, while IF offers certain kinematic benefits. However, real-world sports often require a combination of attentional strategies, and the effects of combined EF + IF instructions on landing mechanics and muscle activation have not been fully studied.
This study will investigate the effects of EF and combined attentional focus instructions on lower extremity and trunk movement, muscle activation, and skill transfer in young female athletes with asymptomatic dynamic knee valgus. The investigators aim to determine whether combined attentional focus training provides greater improvements in landing mechanics, muscle activation, and skill transfer than EF training alone.
Detailed Description
Female athletes experience knee injuries significantly more often, with an incidence rate approximately 3.5 times higher than that of their male counterparts. One of the most common knee injuries is anterior cruciate ligament (ACL) injury, with the risk being particularly high in female athletes, who have a reported incidence of non-contact ACL injuries of 63%.
Approximately 70% of ACL injuries occur without contact, with one of the most frequent causes being dynamic knee valgus which can result in high abduction (valgus) loads during landing after a jump. Dynamic knee valgus describes the frontal-plane knee angle during dynamic tasks such as landing or stepping down, typically occurring in conjunction with femoral internal rotation, contralateral pelvic drop, and hip adduction. Female athletes exhibit significantly greater valgus angles than male athletes, with only 22% of female players classified as having good knee control during jump landing, compared with 80% of male players.
The initial landing phase after a jump requires special attention from injury-prevention professionals, as 31% of ACL injuries occur during this phase. Common biomechanical features during single-leg landing include decreased flexion angles of the ankle, knee, hip, and trunk; increased knee internal rotation and abduction (valgus) angles and moments; lateral trunk flexion; as well as exaggerated ground reaction forces. An important clinical implication of these findings is that athletes need to be taught safer landing techniques.
Recently, the importance of integrating cognitive strategies into injury prevention programs has been emphasized. One such cognitive strategy involves the external and internal focus of attention, in which instructions for executing the movement aim to improve neuromuscular performance and motor learning. In external focus (EF), the athlete's attention is directed to objects or the environment external to the body (e.g., "stand on one leg and slowly bend your knee while keeping your knee over your foot"), while in internal focus (IF), attention is directed toward the performer's own movements (e.g., "stand on one leg and reach slowly toward the cone with your knee while bending your knee").
Previous studies reported that EF and IF instructions have different effects on athletes' kinematic, kinetic, and muscle activation parameters. EF instructions enhance safer and more controlled movement patterns during jump-landing by increasing knee and hip flexion, reducing knee valgus moments, and increasing the overall range of motion compared to IF. IF instructions, on the other hand, may provide certain kinematic improvements, such as reducing knee varus moments and controlling medial-lateral displacement. Recent meta-analyses support these findings, showing that although EF is generally more effective in jumping tasks, both attentional focus types can improve knee flexion.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 30 Years (Adult)
- Sex
- Female
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Females aged between 18-30 years old
- •BMI between 18.5-25 kg/m²
- •Dynamic knee valgus >10° during single-leg squat test (Richardson et al., 2020)
- •Being recreationally active (engage in moderate physical activities at least 3 times a week, with each session lasting at least 30 minutes in the past 4 weeks) (Heinert, 2008)
Exclusion Criteria
- •Trunk, lower back, or lower extremity pain greater than 3/10 on numeric pain rating scale (0-10) in the past 6 months
- •History of surgeries in the lower extremity or lower back that may affect the landing mechanism
- •Currently participating in any lower extremity biomechanics modification program
- •Any medical or physical condition that would prevent safe jumping from a 20-cm box
Arms & Interventions
Combined Focus of Attention Group (CFAG)
After participants meet the inclusion criteria are randomized and assigned to the combined attentional focus group. They will perform training blocks consisting of 5 repetitions and 2 sets of single-leg drop jump landings before and after the evaluations. During the jumps, instructions will focus on combined attentional focus and will be repeated for each jump. A 1-minute rest period will be provided between training blocks.
Intervention: Single-Leg Drop Vertical Jump (Other)
External Focus o Attention Group (EFAG)
After participants meet the inclusion criteria are randomized and assigned to the external attentional focus group. They will perform training blocks consisting of 5 repetitions and 2 sets of single-leg drop jump landings before and after the evaluations. During the jumps, instructions will focus on external attentional focus and will be repeated for each jump. A 1-minute rest period will be provided between training blocks.
Intervention: Single-Leg Drop Vertical Jump (Other)
External Focus o Attention Group (EFAG)
After participants meet the inclusion criteria are randomized and assigned to the external attentional focus group. They will perform training blocks consisting of 5 repetitions and 2 sets of single-leg drop jump landings before and after the evaluations. During the jumps, instructions will focus on external attentional focus and will be repeated for each jump. A 1-minute rest period will be provided between training blocks.
Intervention: External Focus of Attention Instruction (Other)
Control Group
After participants meet the inclusion criteria are randomized and assigned to the control group. They will perform training blocks consisting of 5 repetitions and 2 sets of single-leg drop jump landings before and after the intervention. During the jumps, no instructions will be given. A 1-minute rest period will be provided between training blocks.
Intervention: Single-Leg Drop Vertical Jump (Other)
Control Group
After participants meet the inclusion criteria are randomized and assigned to the control group. They will perform training blocks consisting of 5 repetitions and 2 sets of single-leg drop jump landings before and after the intervention. During the jumps, no instructions will be given. A 1-minute rest period will be provided between training blocks.
Intervention: No instruction (Other)
Combined Focus of Attention Group (CFAG)
After participants meet the inclusion criteria are randomized and assigned to the combined attentional focus group. They will perform training blocks consisting of 5 repetitions and 2 sets of single-leg drop jump landings before and after the evaluations. During the jumps, instructions will focus on combined attentional focus and will be repeated for each jump. A 1-minute rest period will be provided between training blocks.
Intervention: Combined Focus of Attention Instruction (Other)
Outcomes
Primary Outcomes
3D motion analyses
Time Frame: baseline, immediately after the intervention, one week after the baseline
3D motion analysis will be used to evaluate lower extremity and trunk kinematics and kinetics during a single-leg drop vertical jump task. Retroreflective markers will be placed on anatomical landmarks of the foot, shank, thigh, pelvis, trunk, upper extremity, and head using a standardized whole-body marker set. Marker trajectories will be captured using a multi-camera motion capture system synchronized with force platforms to record ground reaction forces. Following a static calibration trial, participants will perform three trials of a single-leg drop vertical jump from a 20-cm platform using the limb demonstrating dynamic knee valgus. Kinematic variables will include peak joint angles of the hip, knee, and ankle in sagittal, frontal, and transverse planes, as well as trunk motion. Kinetic variables will include hip and knee joint moments and peak vertical ground reaction force. Outcome measures will be averaged across trials for pre-, post-, and retention assessments.
Secondary Outcomes
- Gluteal muscle activation (EMG)(baseline, immediately after the intervention, one week after the baseline)
- Forward Step-Down Test(baseline, immediately after the intervention, one week after the baseline)
Investigators
Pelin Pişirici
Assistant Professor, PT, PhD
Bahçeşehir University