Hip-muscle activation during the lunge, single-leg squat, and step-up-and-over exercises

Context: Functional exercises are often used in strengthening programs after lower extremity injury. Activation levels of the stabilizing hip muscles have not been documented. Objective: To document the progression of hip-muscle activation levels during 3 lower extremity functional exercises. Design: Cross-sectional. Setting: Laboratory. Participants: 44 healthy individuals, 22 women and 22 men. Intervention: Subjects, in 1 testing session, completed 3 trials each of the lunge (LUN), single-leg squat (SLSQ), and step-up-and-over (SUO) exercise. Main Outcome Measures: Root-mean-square muscle amplitude (% reference voluntary muscle contraction) was measured for 5 muscles during the 3 exercises: rectus femoris (RF), dominant and nondominant gluteus medius (GMed-D and GMed-ND), adductor longus (ADD), and gluteus maximus (GMX). Results: The RF, GMAX, and GMed-D were activated in a progression from least to greatest during the SUO, LUN, and SLSQ. The progression for the GMed-ND activation was from least to greatest during the SLSQ, SUO, and then LUN. Activation levels of the ADD showed no progression. Conclusion: Progressive activation levels were documented for muscles acting on the hip joint during 3 functional lower extremity exercises. The authors recommend using this exercise progression when targeting the hip muscles during lower extremity strengthening.