Why conditioning matters, and how we train it at Kracht Amsterdam

Ever wondered why some workouts feel easier to sustain than others, or why certain people seem to recover quickly between hard efforts? The answer often comes down to conditioning.

Conditioning is more than just cardio. It’s the ability of your body to produce, use, and recover energy. A well-developed engine helps you train harder, recover faster, and feel stronger in everyday life. It’s also one of the most important factors for longevity, supporting heart health, reducing fatigue, and giving you the freedom to keep moving well for years to come.

And while conditioning isn’t as flashy as hitting a new PR, it quietly makes everything else better: your lifts feel smoother, your metcons feel more sustainable, and your recovery after training (or a long day at work) improves.

Before we start, I’d like to acknowledge that “conditioning” is somewhat of a loose term, and encompasses things like stamina, endurance, fitness, and much more. The point of the article is not to provide a hard scientific definition or model, but to give you a very practical and useful model to understand the concept.

For the rest of the article, I’d like you to think of conditioning as your body’s ability to use and generate energy at different intensities and durations.

Understanding Conditioning Zones

To make sense of conditioning and how to train it, it helps to break it into training zones. Each zone trains a different part of your energy system:

• Zone 1 – Aerobic base building (RPE 1-4)Low intensity, steady pace, long duration. You should be able to hold a conversation. This is the foundation layer, it improves your heart, lungs, and ability to recover and trains the body’s ability to generate energy and remove waste-product. Usually 30-45min +. This also often referred to as “Zone 2” training, referring to the popular (and complex) 5-zone model.

  
  

• Zone 2 – Sustainable work (RPE 5-8)Moderate intensity, challenging but controlled. Training your body to work at threshold paces. Think CrossFit-style workouts where you keep moving without redlining. This develops stamina and efficiency.

  
  

• Zone 3 – High intensity (RPE 9-10)Short, powerful bursts. Sprints, intervals, all-out efforts. Training your body to produce and use a high amount of energy explosively. This builds speed, power, and the ability to push through discomfort.

  
  

At Kracht, our regular classes mostly live in Zone 2 and 3. That’s where you get the most “bang for your buck” in a one-hour session,workouts that build strength, challenge conditioning, and keep training fun and dynamic.

Even though each zone emphasizes certain qualities more than others, the effects are cumulative. Zone 2 includes everything Zone 1 develops, plus more. Zone 3 does the same compared to Zone 2.

So if we look at “benefits per minute,” higher intensities give you broader fitness adaptations than lower ones. But there’s a catch: the higher the intensity, the higher the fatigue cost. That’s why the smartest approach is a mix of intensities.

That said, if your training time is limited, say only 2–3 classes per week, then intensity is king. You’ll get the most return on your investment by pushing harder in those sessions. Once you start training more than 3 sessions a week, doing 1-2 of those at lower intensities could be wise.

How We Train Conditioning at Kracht

We design our training with all of this in mind:

• Regular Classes Most workouts challenge you in Zone 2 and Zone 3: sustainable effort mixed with intensity. That’s why you leave sweaty, accomplished, and stronger every time.

  
  

• Sunday Engine SessionsThese are different. Our weekly “engine” class is closer to the bottom of Zone 2 and top of Zone 1: longer blocks of steady work, often on the rower or bike. It feels less intense in the moment, but it builds your base, boosts recovery, and pays off massively over time.

  
  

• Small Group Conditioning SeriesFollowing the workshop, we’ll run a focused series that lets you go deeper. In these sessions, you’ll experience structured intervals, steady-state efforts, and progressive workouts that grow your aerobic capacity week after week. It’s a chance to train smarter, not just harder.

Practical Examples

So, what does this look like in practice?

• Zone 1 example: 30–40+ minutes on the bike or rower at an easy, consistent pace. You should be sweating a little but able to hold a conversation RPE 4

  
  

• Zone 2 example: 5 rounds of 5 minutes on the rower at a moderate pace, with short rests. Challenging, but sustainable. RPE 7

  
  

• Zone 3 example: 10x 30-second sprints on the bike, with full recovery in between. Short, sharp, and powerful. RPE 9-10

  
  

By blending these approaches, you not only build a stronger heart and lungs, you also gain the ability to recover faster between lifts, push harder in metcons, and bring more energy into your everyday life.

What should you prioritize?

Not every athlete has the same needs, so conditioning work should be prioritized differently depending on your goals, strengths, and weaknesses. A simple way to estimate where you stand is to look at your performance across different time domains:

• Short efforts (0–3 minutes): sprints, heavy barbell cycling, short metcons like “Fran.”

  
  

• Medium efforts (4–12 minutes): workouts such as “Helen” or “Grace.”

  
  

• Long efforts (12+ minutes): chippers, Hero WODs, or benchmark workouts like “Murph.”

  
  

If you crush sprints and short pieces but consistently fall off in longer workouts, that’s a sign your aerobic base could be underdeveloped and you’d benefit from more Zone 1–2 work. On the other hand, if you can hold pace forever but struggle to hit the gears in short metcons, you may need more high-intensity Zone 3 sessions. Don’t forget to also assess your strength and movement capabilities cause these might bottleneck you, and present as conditioning limitations.

While these workout check-ins can give you clues, testing is the best way to know for sure. Tools like a ramp test or structured conditioning assessments give objective numbers for LT1, LT2, and VO₂max, making it much easier to target the right zones in training. During our upcoming workshop, we will get a chance to do this. But if you’re interested in exploring this even more, you can always get in touch with one of our coaches here:

(Link to 1 on 1 pt)

Join the Workshop

Conditioning Workshop: Sunday 28/9, 90 minutes with Coach Daaf

We’ll break down the theory, do a test, and show you how to track and improve your conditioning. This session kicks off our 9-week small group series, leading up to the Kracht Ergathlon.

 Reserve your spot today and start building the engine that will power your training, for performance, for longevity, and for December 13th.