From a functional perspective, there are two primary problems with most typical gym routines. The first is that they train individual muscle groups (biceps, pecs, quads, hamstrings, etc.) instead of movement patterns (e.g., pushing, pulling, lifting, stepping, walking, crawling, jumping, squatting). Second, they typically occur in just a single plane of motion: the sagittal, which involves forward and backward movements used in classic exercises like the squat, biceps curl and even running.