The Effects of Eccentric Training on Hamstring Flexibility and Strength in Young Dance Students

Abstract Objective: The objective of this research is to examine the impact of eccentric training on hamstring flexibility and strength in young dancers during the concluding stages of their foundational dance training program. Methods: A total of 24 female, second-year dance students from Hebei Normal University were selected as participants. They were divided into three distinct groups: Nordic hamstring exercise and single-leg deadlift group (NHE&SLD), forward bending exercises and standing leg lift group (FBE&SLL), and a control group (CG). The study was designed around a 6-week training regimen. An isokinetic dynamometer was used to measure seated knee flexor-extensor strength, while electronic goniometry was employed to measure hamstring flexibility in the supine position. Paired sample t-tests were conducted within each group, and one-way analysis of covariance (ANCOVA) was utilized for comparisons between groups. Results: In the NHE&SLD group, significant disparities were observed in both concentric (T=-5.687, P=0.001) and eccentric (T=-3.626, P=0.008) hamstring strength pre and post-intervention. The pre-intervention dominant leg concentric strength test values significantly influenced the post-intervention outcomes (F=5.313, P=0.001, η²=0.840). Similarly, the pre-intervention dominant leg eccentric strength test values impacted the post-intervention results (F=4.689, P=0.043, η²=0.190). Following the intervention, the NHE&SLD group displayed marked changes in the active straight leg raising angle on both left (T=-4.171, P=0.004) and right (T=-6.328, P=0.001) sides. The FBE&SLL group also revealed significant changes in the active straight leg raising angle on both left (T=-4.506, P=0.003) and right (T=-4.633, P=0.002) sides following the intervention. The pre-intervention left leg concentric strength test value significantly influenced the post-intervention outcomes (F=25.067, P=0.001, η²=0.556). Likewise, the pre-intervention right leg eccentric strength test value significantly influenced the post-intervention results (F=85.338, P=0.01, η²=0.810). Conclusion: Eccentric training can effectively enhance hamstring flexibility and strength in dance students. Traditional stretching exercises mildly affect hamstring flexibility but do not create a significant impact on strength. Compared to pure stretching exercises, eccentric training provides more comprehensive training benefits. It is recommended for dance students to employ eccentric training into their habitually exercise routine.