Improve Your Conditioning With These Evidence-based Tips

metabolic crossfit program

A well-conditioned CrossFit athlete can maintain a high level of output throughout a workout, recover quickly between rounds, and take on a range of movements and exercises with efficiency and precision. Let's talk about why conditioning is so crucial for CrossFit athletes as well as other factors that are impactful for “having a big engine”.

Conditioning in CrossFit

Conditioning in CrossFit is about having a well-rounded level of fitness. This requires its athletes to be able to run 10 kilometers but also make heavy lifts and gymnastics exercises. Aerobic conditioning involves the body's ability to sustain effort over extended periods, while anaerobic conditioning involves intense bursts of effort for shorter durations.

The more your cardiovascular fitness improves, the more efficient your body systems become at transporting, extracting and using oxygen in the working muscles:

  • The heart can pump more blood throughout the body in a given time-frame
  • The blood can transport more oxygen, because more red blood cells are available
  • The muscles can better extract and use the oxygen that is provided by the blood
  • The breathing system gets more efficient, as breathing muscle require less energy relatively.

All of this translates in the athlete being able to perform at their best. This is why it is so important to start your sessions with a proper warm up.

The Evolution of Aerobic Capacity

For decades, researchers thought that only high volume (>45 min) exercise at low intensity (easy running, biking) could improve conditioning.They were mainly biased by the fact that this kind of exercise is predominantly aerobic based, which means that there is always sufficient oxygen available to support the working muscles.

According to the prevailing thought back then, only aerobic based training can improve the cardiovascular system.

Interestingly, in the early 2000’s, researchers started to explore the possibility that shorter bursts of energy production (fi 30s all-out, 4 min rest, repeated 4-6 times) could also improve several aspects of the cardiovascular system and hence conditioning. The results were quite astonishing as more and more reports showed that very low volume, but extremely high intensity had similar, to even better effects on condition than continuous exercise at low pace.

The term High Intensity Interval Training (HIIT) was born.

From then on, multiple studies started to investigate which exercise paradigm was ‘the best’ and ‘the most efficient’ in terms of improving cardiovascular fitness.

The Role of Workout Duration

So if 45 minute sessions aren't optimal for improving cardiovascular fitness, what time frame should an effective program have?

A study from Franch and coworkers, which showed that medium length intervals (4 min) repeated for 4-6 times at a hard, but not maximal intensity provided the best results in terms of improving maximal oxygen uptake (the most frequently used metric in science to quantify conditioning).

This type of training was more time efficient and overall better compared to short intervals (15s on 15s off, 30-40 repetitions) and continuous exercise at slow pace.

References: Franch et al, MSSE, 1998 and Laursen & Jenkins, Sports Med, 2012

The Role of Intensity

How high is too high when we talk about high intensity interval training? That's where the Rate of Perceived Exertion (RPE) comes into play. RPE is a useful tool that measures effort using a scale of 1-10.

what is RPE

A study (Tabina et al, Sports, 2019) looked at how rate of perceived exertion (RPE) can be used in high-intensity workouts to manipulate pacing.

RPE uses a scale (from 1-10) to ask someone how hard the workout feels. Simple, but effective.

Heart rate and lactate was lower when people were instructed to workout at RPE 6 compared to when they had to go ‘all-out’.

Although they did less reps in total, they were able to keep a more steady pace.

This important finding shows that going all-out for every metcon isn't necessarily the best option. It might be beneficial to ease off once in a while and work on movement efficiency rather than the scoreboard.

References: Tabine et al, Sports, 2019

The Secret to Improving Your Conditioning

So how can you ensure that you're getting the best, most effective programming to develop your aerobic capacity? It's as simple as choosing a program that's evidence based. If you're looking for a program that's backed by science, and guaranteed to work, look no further:

The Progrm x WOD Science

The Progrm has teamed up with WOD Science to design a Conditioning program for CrossFit athletes looking to improve their work output. This program is backed by science and based on the same evidence outlined above to guarantee improvement in your performance.


  • Duration 6 weeks.
  • Focused on improving your conditioning capacity.
  • 3 training days per week all based around the available science.
  • Identify and improve your specific Functional Threshold Power (FTP).
  • You may choose any Concept 2 machine you have available (Bike / Row or Ski) for the testing and training.