Isokinetic Quadriceps Strength at Slower Speeds Following ACLR More Strongly Influences Hop Test Performance in Adolescent Athletes.
Zac Blaydes, Gabrielle Griffin, Taha Saifullah, Philline Tumbaga, Jeff Nepple, Joseph HannonBackground
Return-to-play (RTP) criteria remains inconsistent for adolescents following anterior cruciate ligament reconstruction (ACLR). Isokinetic strength testing (ISKT) and functional horizontal hop testing are commonly used to assess readiness, but the optimal ISKT testing protocol for predicting functional performance in adolescents has yet to be defined.
Hypothesis/purpose
The purpose of this study was to examine the relationship between quadriceps peak torque at multiple isokinetic testing speeds and functional hop test symmetry. It was hypothesized that strength measured at 60°/sec would demonstrate a stronger association with hop performance than measures obtained at 180°/sec and 300°/sec.
Study design
Prospective cohort study
Methods
One hundred pediatric and adolescent patients (15.1 ± 2.0 yrs) completed a standard RTP assessment at a mean of 6.3 + 0.4 months following ALCR. ISKT was assessed at 60 °/sec, 180 °/sec, 300 °/sec. Hop testing included the single hop for distance, triple hop for distance, crossover hop for distance, and 6-meter timed hop. ISKT values were examined as limb symmetry indices (LSI) and as normalized values (Nm/KG). Multiple linear regression analyses were used to assess the influence of ISKT speed on hop test performance.
Results
ISKT LSI at 60 °/sec was significantly associated with single hop (β = 0.508, 95% CI [.18,.75], p = 0.001), triple hop (β = 0.437, 95% CI [.09,.48] p = 0.001), and crossover hop (β = 0.448, 95% CI [.09,.55] p = 0.006). These results were consistent when examining that data as normalized at 60 °/sec for the single hop (β = 0.641, 95% CI [27.4,81.7] p = 0.001), triple hop (β = 0.579, 95% CI [59.9,202.51] p = 0.001), and crossover hop (β = 0.529, 95% CI [46.0,205.8] p = 0.006). ISKT at 180 °/sec and 300 °/sec did not significantly influence hop performance.
Conclusion
In adolescents following ACLR, quadriceps strength assessed at 60 °/sec, demonstrates the strongest relationship with functional hop test performance.
Level of Evidence
Level 3