Lateral motion refers to moving horizontally in a setup. For this post, we’ll be focusing on mallet instruments, meaning moving higher or lower.
The basic principal is simple: the larger the motion, the harder it is to execute. When playing with 4-mallets, consider the motion laterally as well as any interval change. Remember that graduated bars will require an interval change of sorts even if the part is jumping in an exact octave.
Marimba poses a particularly big challenge. The instrument is large enough that extreme distance between hands not only requires large motion with the upper body, but the lower body as well. Generally, standing with feet shoulder-width is the ideal stance, but extreme distances will require one to lower their body closer to the instrument, and adjust to a wider stance in the process. With this in mind, it’s important to consider that some players will not be physically capable of playing extreme intervals as a result of their height and wingspan. Andrew Thomas’s Merlin, for example, ends with a virtuosity passage that is not uncommonly transposed an octave up in the left hand.
Almost anything is possible at a slow enough tempo, and it goes without saying that difficulty increases with tempo.