Post by Jacob Bond

K A L S U (…and the room goes quiet.) Why does Kalsu absolutely devastate people? Great question! Understanding the answer might enhance your understanding of conditioning, programming, and what it means to build an engine. 😊 Two things make Kalsu particularly revealing: 1. It rewards athletes who perform large volumes of continuous work. 2. It punishes athletes whose conditioning consists primarily of classical MetCons, with unstructured rest and non-antagonistic movements designed to maximize total power output. The ability to keep moving is everything. One of the fastest Kalsu performances I could find was 9:59 by Kelley Jackson in 2016. Watch her video. At those loads, she's resting at most 10 seconds per round, if not less. In effect, she's in constant motion. Now think about classical CrossFit MetCons. Often, more than 50% of the workout is spent transitioning or resting. That's a major issue if you want an engine capable of exceptional Kalsu performances. To do well at Kalsu, you have to keep moving. Why? Despite being "distinct" modalities, burpees impose metabolic stress across almost all the same muscle groups as thrusters. Your delts, midline, quadriceps, and posterior chain are under continuous, but oscillating, demand. The heavy contractions of a moderate-heavy thruster are supersetted with lighter contractions during burpees. That's very different from alternating movements that allow one muscle group to recover while another works. Consider Cindy! Cindy maximizes total power output, which delivers a unique and desirable stimulus. But here's the distinction: You're not developing the capacity to perform pull-ups, push-ups, OR squats for 20 minutes. You're developing the capacity to perform pull-ups, push-ups, AND squats for 20 minutes. Note the difference. At the level of the MUSCLE, Cindy doesn't optimize your body's efficiency at sustaining continuous power output. When contractions become difficult, you rest as needed. This further diminishes the stimulus for developing continuous work capacity, both locally at the muscle level and systemically at the cardiorespiratory level. Accumulating work isn't necessarily the same as sustaining it. Think of pressure-washing a deck. Cindy is like blasting the deck in brief spurts at moderate pressure, alternating between different areas. Kalsu is like blasting almost continuously, alternating between moderate and very high pressure across overlapping areas. Imagine two pressure washers, each designed for one condition. Which performs better when asked to work continuously under fluctuating demands? You already know... Kalsu doesn't care how good you are at resting. It's the top of the minute: now do your damn burpees. This is why so many CrossFitters fear Kalsu. If you don't do enough machine work, density intervals, and instead overdose on classical MetCons, Kalsu can expose your poor conditioning in a hurry. This is why Kalsu devastates typical CrossFitters.