Side Plank
The side plank is an isometric hold on one forearm and the edge of the feet that trains the obliques and the muscles along the side of the hip. The NSW guide prescribes it per side, so every set is performed twice, once on the left and once on the right.
How to Perform It
Lie on one side and support your body weight on one forearm with the elbow directly below the shoulder. Rest the other arm along the side of your body. Lift the hips so the spine and legs form a straight line and hold that line by statically contracting the core muscles. Do not let the hips sag toward the floor. Hold for the prescribed time, then switch to the other side. The guide gives two progressions: keep the core contracted while lifting the top leg by abducting the hip, or raise the body higher by straightening the support arm and holding your weight on one hand with the opposite arm extended straight above you.
Why It Matters for BUD/S
The side plank covers the lateral trunk, a region the plank, sit-ups, and bridge leave mostly untouched. That lateral strength keeps the pelvis level during single-leg loading in running and lunges and keeps the body from rolling or bending sideways in the water during the combat sidestroke, which is itself a side-lying position. The guide's stated purpose for core training is balance, alignment, stability, and injury reduction. Weak obliques show up as a hip that drops on every stride, and that pattern is a common source of lower back and knee complaints under the volume BUD/S imposes.
Where It Sits in the 26-Week Plan
Side planks are part of the core block that appears on Monday, Wednesday, Thursday, and Friday of every training week. Unlike the plank, the side plank stays at 2 sets per side for the entire program, and the progression comes from time instead of volume. Weeks 1 through 6 call for 2 sets of 30 seconds on each side, and the hold grows through 40, 45, and 50 seconds before reaching 2 sets of 60 seconds per side in weeks 22 through 26. Because each side is counted separately, a full side plank prescription always means four holds per session.
Prescription by program week (each side)
| Weeks | Sets x reps |
|---|---|
| 1-6 | 2 x 30 sec |
| 7-11 | 2 x 40 sec |
| 12-16 | 2 x 45 sec |
| 17-21 | 2 x 50 sec |
| 22-26 | 2 x 60 sec |
Stack your feet and push the bottom hip up toward the ceiling. If one side is clearly weaker, start each session on that side.
Related Terms
Core exercises in the NSW preparation program target the trunk stabilizers — abdominals, obliques, lower back, and hip muscles — through a progressive rotation of planks, bridges, bird dogs, supermans, and side planks. These exercises build the trunk stability that supports every movement in BUD/S, from running to swimming to log PT.
The plank is an isometric hold on the forearms and toes that trains the abdominals, lower back, and shoulders to keep the body rigid. It is the simplest core exercise in the NSW guide and the one with the longest holds, reaching 60 seconds per set by the end of the program.
The combat sidestroke (CSS) is a hybrid swimming technique developed for military applications that combines elements of sidestroke, freestyle, and breaststroke. It is the preferred stroke for the PST 500-yard swim and the primary swimming technique used throughout BUD/S training and NSW operations.
The bridge is a floor exercise that trains the glutes, hamstrings, and lower back by lifting the hips off the ground while lying on your back. The NSW guide programs it as an alternating single-leg movement, so each rep also tests pelvic stability on one side.
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