(15) Difference between well-practiced high bar and low bar back squat is not in joint moment but in joint ROM and mechanical work of hip and knee

Purpose: The back squat is a fundamental multi-joint resistance exercise that differs in muscle involvement between its high-bar (HBSQ) and low-bar (LBSQ) variations. This study aimed to compare the biomechanical variables (net moment, range of motion (ROM), and mechanical work) of the hip and knee joints between HBSQ and LBSQ performed at identical relative loads by well-practiced participants.

Methods: Prior to the data collection, eleven young men completed a familiarization period of at least three months of performing both HBSQ and LBSQ with progressively increasing respective 8RM loads. A motion capture system (VICON) and a force platform (Kistler) were used for data collection. The participant performed five repetitions of four sets of both squats at respective 8RM loads. Biomechanical variables were calculated based on the inverse dynamics using a software (MATLAB). Two trials, one from the HBSQ and one from the LBSQ, which had exerted approximately the same total mechanical work were selected for comparison. A paired two-tailed t-test was used to compare the differences between the squats for each variable.

Results: The results showed no significant difference in peak joint moment between HBSQ and LBSQ for both the hip (HBSQ: 316 ± 52 Nm vs. LBSQ: 338 ± 62 Nm; Table) and the knee (HBSQ: 221 ± 37 Nm vs. LBSQ: 241 ± 45 Nm; Table). The knee joint ROM and mechanical work were significantly greater in the HBSQ compared to the LBSQ (knee joint ROM, HBSQ: 101 ± 11 deg vs. LBSQ: 93 ± 5 deg, P < .05; knee joint work, HBSQ: 277 ± 92 J vs. LBSQ: 212 ± 76 J, P < .01; Table). Conversely, hip ROM and work were greater in the LBSQ than in the HBSQ (hip joint ROM, HBSQ: 93 ± 8 deg vs. LBSQ: 98 ± 6 deg, P < .05; hip joint work, HBSQ: 303 ± 87 J vs. LBSQ: 354 ± 109 J, P < .01; Table).

Conclusions: It was found that when each individual practices both squats well, there is no difference in joint moment between HBSQ and LBSQ for both hip and knee. Differences in training effects between HBSQ and LBSQ for knee and hip extensors are primarily due to differences in joint ROM and mechanical work.
PRACTICAL APPLICATIONS: When prescribing either HBSQ or LBSQ according to each individual's characteristics and goals, it is useful to increase the joint ROM associated with the muscles to be strengthened.

Acknowledgements: None