ACL injuries are prevalent in sports, particularly in activities that involve sudden stops, changes in direction, or direct impact on the knee. These injuries can have significant consequences, including pain, instability, and long-term joint damage(Montalvo et al., 2019). Understanding the mechanisms and risk factors for ACL injury is crucial for injury prevention and rehabilitation(Takahashi \& Okuwaki, 2017). Eccentric contraction involves the elongation of a muscle while it is under tension. The hamstrings are a muscle group situated at the back of the thigh, comprising the biceps femoris, semitendinosus, and semimembranosus. The hamstrings play a crucial role in knee stability, particularly in preventing excessive anterior translation of the tibia relative to the femur, which is one of the mechanisms of ACL injury (Gronwald et al., 2022). Strengthening the hamstrings, especially through eccentric contractions, can enhance knee joint stability(Jones et al., 2019). Eccentric muscle contractions involve the lengthening of a muscle while it is contracting. These contractions are particularly effective in building strength and improving muscle function (Al Attar et al., 2017). Research suggests that eccentric hamstring strengthening exercises can enhance muscle activation, increase muscle strength, and improve neuromuscular control, all beneficial in ACL rehabilitation (Opar et al., 2012). Eccentric strengthening exercises for the hamstrings are commonly prescribed in rehabilitation programs for ACL injuries, because they provide dynamic stability to the knee joint (Lodge et al., 2019). ACL injury often occurs during dynamic movements such as cutting, pivoting, or landing from a jump. Biomechanical studies have identified specific movement patterns and muscle activation sequences associated with ACL injury risk (Buckthorpe et al., 2019).
Rehabilitation protocols for ACL reconstruction typically include strengthening exercises, neuromuscular training, proprioceptive exercises, and functional activities. Eccentric hamstring exercises are commonly incorporated into these programs to improve muscle strength, control, and proprioception around the knee joint(Vatovec et al., 2020).
Despite the widespread use of eccentric hamstring training in ACL rehabilitation after reconstruction, there may be gaps in our understanding of the effectiveness of eccentric hamstring contractions in ACL rehabilitation,for rehabilitation after ACLR, progressive eccentric cycle training was not more clinically effective than concentric training (Giovanni Milandri, Sudesh Sivarasu, 2021). Addressing these gaps can provide valuable insights for providing rehabilitation protocols and enhancing outcomes for individuals recovering from ACL injury.
Overall, the background of the study highlights the importance of understanding the relationship between eccentric hamstring contraction and ACL grade 1 injury rehabilitation. The study aims to provide insights into how eccentric hamstring contraction may influence ACL grade 1 injury rehabilitation.
4\. THE OBJECTIVE OF THE STUDY
1. To assess the effectiveness of eccentric hamstring contractions on changes in sports performance, using various testing methods, in the intervention group.
2. To evaluate the impact of eccentric hamstring contractions on quality of life and psychological well-being in young male football players with non-contact grade 1 ACL injury.
3. To compare sports performance outcomes between the intervention and control groups in young male football players with non-contact grade 1 ACL injury.
The overall aim of the study is to evaluate the impact of eccentric hamstring contractions on sports performance in young male football players with non-contact grade 1 ACL injuries hamstring exercises on sports performance among young male football players with non-contact grade 1 ACL injury in UAE. The participants recruited in the study will be randomly assigned to one of two intervention groups: a control arm (usual physiotherapy exercise will be given) and, an intervention Arm (custom-tailored eccentric hamstring exercises along with physiotherapy will be given). We assumed no interaction between the treatment arms.
Operational Definitions
* ACL - The anterior cruciate ligament (ACL) is one of 2 cruciate ligaments that aids in stabilizing the knee joint. It is a strong band made of connective tissue and collagenous fibers that originate from the anteromedial aspect of the intercondylar region of the tibial plateau and extends posterolaterally to attach to the medial aspect of the lateral femoral condyle, where there are two important landmarks; The lateral intercondylar ridge which defines the anterior boundary of the ACL, and the bifurcate ridge which separates the 2 ACL bundles(Evans J, 2023).
* Eccentric hamstring exercises - An eccentric strengthening exercise program for the hamstring muscles that can be performed during training can help prevent hamstring injuries in soccer players(Schache A, 2012).
* Nordic hamstring curl training (NHCT), a type of training based on eccentric contractions aimed at increasing hamstring muscle strength and performed on flat ground without requiring special equipment, has been accepted as a popular training method(Al Attar, 2017).
* Running, one of the most basic human motions, is characterized by a typical cyclic motion and an airborne phase involving projection of the body. Sprint running is recognized as the fastest mode of unaided human locomotion (Michiyoshi Ae, 2017).
Pain Categories:
1. Mild: Pain intensity 1-3/10, occasional discomfort, no interference with daily tasks.
2. Moderate: Pain intensity 4-6/10, noticeable during activities, some difficulty with strenuous movements.
3. Severe: Pain intensity 7-10/10, significant pain at rest and with movement, difficulty with daily activities.
* Swelling Categories:
1\. Mild: Slight increase in size, no significant loss of motion, resolves with rest.
2\. Moderate: Noticeable swelling, some difficulty with knee movement, lasts several hours or days.
3\. Severe: Significant swelling, major restriction of movement, may require medical intervention.
