Constantly varying functional movements performed at high intensity. Moving fast, lifting weights and learning skills. The goal in CrossFit is to get better at every aspect and improve the work capacity across broad time and modal domains. But what about the low heart rate training? This article observes the role of low heart rate training for a CrossFit athlete and its’ necessity in order to become a better athlete.

A good aerobic condition is a cornerstone of health and fitness. Aerobic training is known to:

  • Improve oxygen usage in the muscles
  • Increase heart’s mass and volume
  • Improve ventilation in the lungs
  • Reduce systolic and diastolic blood pressure


What does it mean for an athlete?

Aerobic training improves the function of lungs, heart and arteries, so you get oxygen in and carbon dioxide out. With good aerobic condition, your muscles utilize oxygen more efficiently in the mitochondria of your muscles. Aerobic training also makes your heart bigger and stronger, so it can pump larger amounts of blood in a single heartbeat. This decreases both your resting and workout heart rate. The arteries, capillaries and veins become more flexible, which is one reason behind the lower blood pressure.

All these training adaptations mean that the body is able to sustain a higher percentage of aerobic capacity during an exercise without lactate accumulation. This is very beneficial for an athlete. Maintaining your heart rate below the lactate threshold for a longer period in metcons enables you to keep moving longer before the workout starts to feel tiring. It is safe to say that a good aerobic condition is the basis of health and fitness.

Aerobic training in the traditional sense includes longer training sessions at lower heart rate. But high-intensity interval training, or HIIT, has been the new subject of studies. HIIT has been shown to be just as efficient in enhancing aerobic capacity. If you enjoy working out intensely for a shorter period in contrast to a longer, slower paced workout, HIIT seems to be as good a method to improve your aerobic capacity. Furthermore, HIIT also improves the anaerobic energy systems. This side of the energy metabolism doesn’t have a major role in your normal day-to-day life but is huge in CrossFit.


What are aerobic and anaerobic?

Aerobic and anaerobic thresholds may be familiar to you if you have a background in endurance sports. These thresholds are not fixed numbers, which means they can change as your fitness improves and they are somewhat sport specific. Each individual has their own thresholds and you should note that your numbers are not comparable to your training partner’s numbers.

On the aerobic threshold your body starts to produce lactate, but it´s still not building it up. If you don’t have an accurate, up to date knowledge of your thresholds, you can go by feel. You are on the aerobic threshold when your breathing begins to deepen but you don´t feel exhausted. On the RPE scale it would mean something around 5-6. You can still talk and the exercise feels relatively light. During aerobic metabolism, your body creates energy by burning carbohydrates and fats in the presence of oxygen.

Anaerobic threshold is the point when lactate starts to build up in your system. Anaerobic metabolism kicks in when the aerobic system can no longer keep up with the energy demand caused by the movement. During anaerobic metabolism the body burns stored glucose without oxygen to supply the additional energy demand and lactate forms faster than body can metabolize it.



How hard should I go?

The longer you can fuel your exercise with the aerobic system the better. We all know someone at the box who has a background in endurance sport and how he or she just crushes the long bodyweight workouts. These athletes have higher aerobic and anaerobic thresholds, which enables them to move at relatively high intensity without building up lactate.

The aerobic and anaerobic energy systems are both stimulated with HIIT but doing HIIT doesn’t raise your thresholds automatically. Focusing solely on HIIT will improve your aerobic capacity to a certain level. You can aim to improve your aerobic energy metabolism and raise your anaerobic threshold by working out just below your current anaerobic threshold level. Measuring heart rate during workout gives you information about the training intensity and the expected workout stimulus.

Since the early days, a common problem in CrossFit has been the continual high intensity. There is no point going all out every time you train. No one can sustain that forever. Not even the elite athletes. Instead, try to train most of your WODs around 80%. Go all out no more than once a week and use scaling options that allow you to crush these workouts. If you want to develop your aerobic metabolism, do longer running, rowing, swimming or other low-intensity workouts at a pace that is just below your anaerobic threshold. However, the same stimulus can be obtained with the daily activity. Walking or cycling between places, taking stairs instead of the elevator and so on. If you’re smart, there’s no need to give aerobic training an extra focus because the daily activity fulfills the need. In this case, going along with your box’s programming will keep you well balanced and is enough to improve your work capacity comprehensively.