Appropriateness of Tibial Rotation for Isolation of the Medial and Lateral Hamstrings

Background. It is unclear whether the clinical use of tibial rotation to measure the strength of the medial hamstrings and lateral hamstrings in isolation is based on sound scientific evidence or is simply based on anatomical features. Objectives. To verify the appropriateness of tibial rotation for isolation of the medial hamstrings and lateral hamstrings, the participants performed neutral rotation (NR), external rotation (ER), and internal rotation (IR). Methods. Forty-six young and healthy adults (age 21.9 ± 2.2 years, height 167.9 ± 8.6 cm, the weight of 63.8 ± 13.9 kg) participated in the study. The electromyography (EMG) activity and knee flexion torque were measured and compared among different postures; NR, ER, and IR. Results. The Max of the EMG activity of the biceps femoris long head, semitendinosus, and semimembranosus muscles was significantly reduced in ER and IR compared with that in NR. There were no significant differences in muscle activity between ER and IR. Knee flexion force and torque were significantly reduced in IR compared with those in NR and ER. EMG activity was significantly diminished during tibial rotation compared with that in NR. Conclusion. Contrary to the general assumption, IR and ER had a limited influence on the isolation of medial hamstrings and lateral hamstrings; thus, they may be unnecessary for medial hamstrings and lateral hamstrings normalization. The uniform training of the hamstring muscles in NR for MVIC may be more appropriate than isolating the muscles in ER and IR.