Background: The countermovement jump (CMJ) is a valid and reliable test of lower extremity (LE) muscle power. However, the CMJ may not be appropriate during early-stage rehabilitation of injuries. Functional muscle strength tests (FMSTs) could evaluate LE muscle power with lower joint reaction forces.
Hypothesis: The lateral step-up test (LSUT), 5 times sit to stand (5×STS), and 30-s chair stand test (30CST) could predict CMJ jump height (JHt) and jump peak power (JPow).
Study design: Cross-sectional study.
Level of evidence: Level 2.
Methods: Eighty-one young adults performed 3 CMJs to measure JHt and JPow using an electronic jump mat and speed analyzer. Participants also performed three FMSTs: 1 trial of the LSUT and a modified trial of LSUT touching the ground with the heel only (MLSUT); 2 trials of the 5×STS; and 2 trials of the 30CST, in a randomized order. Spearman rho correlations and hierarchal multiple linear regressions were used to determine whether FMST performances predicted JHt and JPow, after controlling for sex, body height, and body mass.
Results: 30CST, LSUT, MLSUT, sex, body mass, and body height were significantly associated with JHt (P < 0.05). LSUT, sex, body height, and body mass were significantly associated with JPow (P < 0.05). Hierarchical regression analyses showed that the 30CST significantly predicted JHt (P < 0.01) and JPow (P = 0.03), independent of sex, body height, and body mass.
Conclusion: 30CST performance predicted JHt and JPow in young adults.
Clinical relevance: The 30CST is easy to perform, requires equipment found readily in clinics, and predicts LE muscle power. This test could be used to track progress during the early stages of LE injury rehabilitation.
Keywords: countermovement jump; jump power; lateral step; muscle strength; sit to stand.