As we eluded to in our previous post, aerobic conditioning is training performed using the body’s aerobic energy system, is typically performed at around 70% of your max heart rate, and is relatively long in duration. Aerobic conditioning is the base of your CrossFit pyramid, and the wider the base the higher that pyramid can go.
Long duration steady state (LDSS) training is a common method that is used to develop your aerobic conditioning. Long runs, rows or bike rides performed at around 70% of your max heart rate are examples of this. One of the benefits of LDSS training include developing cardiovascular efficiency, which can improve the delivery and utilisation of oxygen to working muscles. Whilst there aren’t many CrossFit workouts that require you to work continuously for a prolonged period of time, improving your cardiovascular efficiency can aid your recovery from training, and in a competition or double training day scenario will aid your recovery between workouts. There is also a line of research investigating the notion that LDSS training may also help to prevent soft tissue injury.
When your programming your LDSS training take into account two main variables. The intensity of this type of training should be around 70%. Ideally you can measure this using a heart rate monitor, if not you will have to go by feel a little bit. You should be working at an intensity you can maintain for the duration of the session, without any real drop off in pace. The duration of the session will depend on your current level of aerobic fitness. A beginner may be able to maintain this pace for 20-30 minutes, your seasoned competitor should be able to maintain this intensity for over an hour. Whilst this type of training may seem boring you can make it interesting, use a combination of cyclic exercises where you can control the intensity, and gradually increase the duration of your session over time to provide the overload needed to cause your body to adapt.
A second method of developing your aerobic conditioning is using something I like to call moderate intensity interval training (MIIT). In my opinion this is more specific to CrossFit, and allows for more variation in your training. This method also allows you to develop muscular endurance in movements that are often limited by muscular endurance rather than strength or skill, such as wall balls or kettlebell swings.
With the goal of aerobic conditioning in mind, I plan intervals that include working time of anywhere from 6-15 minutes, and a rest time of between 25 and 40% of the working time. The intensity of these intervals should be around 75%, although that number sometimes rises to around 80%. In these intervals I like to combine your typical cyclic exercises, running, rowing or biking, with CrossFit style movements such as wall balls, burpees, double unders, where the load is light and the athlete can move continuously throughout the interval. To control the intensity of these intervals, you can prescribe set paces for cyclic exercises such as row pace or RPM on the assault bike, and you can select exercises that only allow an athlete to move at a pace which keeps the intensity in the right place. For example, swapping burpee box jumps for burpee box step ups, can remove the temptation for the athlete to move too fast. The exercises or loads you choose should also allow an athlete to keep moving, and not have to break the reps or reach muscular failure – remember the goal here is aerobic conditioning.
As mentioned earlier I find that the variation in movements, the duration of the intervals and the focus you can place on specific muscular endurance makes this method of developing your aerobic fitness more specific to CrossFit. As with LDSS training, these sessions should gradually be progressed over time. When performing MIIT there should be little to no drop off in pace between rounds, so it is important that you work at an intensity that is appropriate for you, and allows this to be the case. I would also advise beginner athletes to start with sessions that last for around 20-30 minutes, and again you can gradually increase the length of these sessions over time to create overload.
In summary –
This is the first in a series of blog post based around conditioning in CrossFit. Conditioning has become one of those words that gets thrown around a lot and is a very broad term that needs to be broken down in order to fully understand its components. This first blog post will break it down, and subsequent posts will go into more detail about how we develop it.
Conditioning is generally a term used to describe a training piece that is intended to develop either your aerobic or anaerobic capacity, and the key to designing programmes that develop conditioning is an understanding of the body’s energy systems. The primary function of all the body’s energy systems is to resynthesise ATP. ATP is essential for muscle contraction, and is finite, meaning it will run out if the body doesn’t reproduce it.
The aerobic energy system is the body’s primary source of energy, and uses readily available oxygen to resynthesise ATP within cells. This is a great continuous source of energy but it is a bit slow, so can only be used during low to moderate intensity exercise. What do we class as low intensity exercise? Any exercise that is below your lactate threshold, typically around 70% of your max heart rate, and is relatively long in duration. In CrossFit terms, think 10k row, triathlon style events or long runs.
The anaerobic energy system plays a big role in most CrossFit workouts, and can be split into the lactic or glycolytic energy system and ATP-PC system. For the time being we will focus only on the lactic energy system. This energy system uses blood glucose, and glucose stored in muscle cells to resynthesise ATP through a process called glycolysis. No oxygen is required making ATP production much faster, however oxygen is required to remove the waste product of glycolysis – pyruvic acid. Oxygen reacts with pyruvic acid to again resynthesise ATP and provide more energy, a by product of this second reaction is lactic acid, a build up of which can significantly impair muscle function. So it is the job of oxygen to break down lactic acid and reduce the decrement in muscle function, easier said than done! As ATP is resynthesised faster through the lactic energy system it can fuel workouts that are performed at a much higher intensity than the aerobic energy system, again in CrossFit terms think Fran or Grace.
Now it’s important not to think of these energy systems as stand-alone sources of energy. Your 15-minute AMRAP is too long to be performed using purely the lactic energy system, but your likely to be working at an intensity higher than 70% of you max heart rate. Energy systems are constantly interacting, as one becomes exhausted another takes over, therefore it is important not to focus solely on one or the other. To be a well-rounded CrossFit athlete you need to have well developed aerobic and anaerobic energy systems. Over the course of the next couple of articles we will first look at how to effectively develop each energy system, and then look at how we prioritise, integrate and maintain each energy system over the course of a season.
In summary –