Bodyweight Squat Movement Changes after a High-Intensity Short-Rest Workout

High intensity (≥75%1RM), short rest (≤30 seconds) workouts (HISR) have increased in popularity in recent years despite very little scientific study as well as contradicting the American College of Sports Medicine (ACSM) position stand. The purpose of this study was to assess the changes in movement associated with the fatigue resulting from a HISR workout. 14 males underwent a 3 dimensional analysis of 5 bodyweight squats before and after a HISR workout. Peak angle, total displacement and rate were assessed for knee flexion, trunk flexion, hip flexion, hip rotation and hip adduction. Subjects were split in to two groups: high lactate (n=7) and low lactate (n=7). Separate 2x2 mixed model ANOVAs were used to assess differences between time points (pre-test, post-test) and groups (high lactate, low lactate) for the dependent variables. We observed a significant group x time interaction for peak knee flexion (F=5.55, P=0.036). Post hoc tests revealed that the high blood lactate group had a significantly lower peak knee flexion than the low blood lactate group after the HISR workout. We observed a significant main effect for time for the following variables: knee flexion peak, displacement and rate; hip flexion peak, displacement and rate; hip adduction peak, displacement and rate; hip rotation displacement and rate. When analyzing the movement of the bodyweight squat before and after a highly fatiguing resistance exercise protocol, it is clear that many of variables were significantly different, which could lead to an increased risk of injury