Day 20 raises the climber challenge to 300. As on Day 8 there are no levels and no fixed rest - just a total, split however keeps the plank honest and the legs moving. Six sets of 50, ten of 30, fifteen of 20: any of those gets you there, and the best split is the one where the final set looks like the first.
The extra hundred is the whole story. Two hundred climbers twelve days ago was a plank held through a long sprint; three hundred is that plank held half as long again, and the shoulders are the part that notices. Climbers never let the upper body rest, which is why the total matters more than it would for almost any other running movement - every one of the 300 knee drives is also a moment of a high plank. Reps are totals, so that is 150 per side.
Hips low and level, shoulders over the wrists, knees driving fully under the body. The first signs of fatigue are a rising hip line and shortening knee drives - when either shows, end the set, rest, and continue. Keep a rhythm with the breath. Short rests between modest sets will beat long rests between huge ones.
Three hundred is one hundred more than Day 8 - the plank is the same, the shoulders just have to hold it longer.
Make it Harder: Run the total in sets of 100 with 30 seconds between them.
Make it Easier: Step the knees in rather than running them and split the total into sets of 15.
