Updated: Dec 5, 2018
Over the past few years aerobic training or cardiovascular training has been made out to be the killer of gains, make you look ‘skinny fat’ whatever the hell that is, and all but useless unless you want to run marathons.
If you’re someone who avoids cardio training like the plague, it could be your missing link to improving performance, recovery and health.
Firstly, let’s look at what fuels our training i.e. energy or Adenosine Triphosphate (ATP). ATP is the body’s currency for providing work such as muscle contractions when moving and lifting. Now to continue this work, the body needs to re-generate this ATP to keep up with the demands of energy expenditure. It can do this one of two ways, with oxygen (aerobically) or without oxygen (anaerobically). Anaerobic energy production has a high turnover rate and can produce ATP much faster than aerobic energy production. However we can only regenerate ATP anaerobically for a short period of time due to either depleting energy stores of phosphocreatine or the inefficient conversion of ATP from anaerobic glycolysis. Not to mention the fatiguing components of this type of energy production.
On the other hand, your body can produce energy aerobically for a very long time and is very efficient at regenerating ATP with the only by products being CO2 and water, meaning no fatiguing effects. The only downside is the regeneration is much slower than anaerobic production.
So when thinking of things such as sprints or 1 rep max attempts, we assume that these are exclusively anaerobic and therefore aerobic training has no bearing. This assumes there is some magical switch where the body depletes one energy system and moves on to the next. This is wrong. All 3 energy systems are active at the same time with the type of activity determining how much each energy system contributes to ATP production.
Let’s relate this to activities that you would consider anaerobic. During 200m sprints a study found that the aerobic system contributed 30% to energy production. Even a heavy set of 5 reps has the aerobic system contributing up to a 1/3 of the energy required. So now we know how we produce energy and how our aerobic system is more active than you think. How does aerobic training fit in if all you want is to get stronger/build size?
Well as we said earlier, while the anaerobic systems produce energy quicker, it also produces a lot of by products resulting in muscular fatigue. This means you gas out, slow down, or hit failure on a lift. The aerobic system produces no fatiguing by products so if we could produce more energy aerobically for any given activity it means we would have to use less energy anaerobically meaning those fatiguing by products would be offset or delayed. This is known as the anaerobic power reserve. If we had two athletes with the same background and same overall power output but athlete A had a higher contribution from anaerobic energy production and athlete B a higher contribution from aerobic energy production, athlete B wouldn’t fatigue as quickly. This means athlete B would be able to perform better. Relating that to lifting weights, athlete B could do the same weight as athlete A and experience less fatigue, feeling more prepared for subsequent sets. Or athlete B could lift more weight and experience the same fatigue as athlete A lifting less weight, therefore increasing performance.
Next, your aerobic system is what actually replenishes your anaerobic systems ability to produce ATP! The more efficient your aerobic system is, the quicker this process can take place. Think about recovery between sets, the more efficient this recovery (aerobic system) the better you will perform on subsequent sets and the more total volume you can handle per session. As we know volume is one of the major factors in training adaptation, especially for intermediate and advanced athletes. So the more volume your body can handle from an efficient aerobic system, the more likely you’ll continue progressing with your training. Along with performance benefits, less fatigue during sets and better recovery between sets means you are less likely to see a drop in technique and thus reduce injury risk.
So that’s how cardiovascular training can help you during your session. What about between sessions?
Aerobic exercise executed correctly (more on that later) is very parasympathetic dominant and helps the body switch into our rest and digest mode (see my article on HRV here). This means recovery between sessions can be enhanced and with minimal impact on subsequent sessions due to lack of fatigue inducing by products. This is where ‘active recovery’ stems from. Aerobic training will utilise this nervous system shift, improve blood flow and clear out waste products. So not only will you elicit the benefits during your session but you can also enhance your recovery ready for your next big lifting session.
Now even though I have gone over the benefits of an efficient aerobic energy system, it’s not the only answer, just another piece of the training puzzle. Sprints/intervals have been shown to elicit aerobic improvements as well as anaerobic improvements and obviously in a shorter time frame. However think about the impact on the body high intensity intervals will have compared to a steady state cycle in terms of recovery for your next session. So goals, training objectives and programming will dictate which one you may need. Goals such as strength may require less aerobic training, however studies show that aerobic training may not have as much impact on hypertrophy (size) as we once thought so I think utilising both strategies according to goals is the way forward. Next we need to determine how efficient your aerobic system is and a good way to determine that is through an assessment. Resting heart rate, heart rate recovery and heart rate variability are all good ways at testing the ability of the aerobic system. Resting heart rate should be at least low 60s to show good aerobic conditioning, however age and some medical conditions can alter resting heart rate which is why I prefer heart rate recovery (HRR). HRR is a good tool to test your recovery after intense bouts of exercise, showing aerobic fitness and endurance. Within 1 minute of ceasing exercise you should see a considerable drop in heart rate, ideally to the 130 bpm mark. Heart rate variability (HRV) is another great way to test aerobic system robustness as well as nervous system activity, helping you to determine how hard you train and when. Again refer to my article here.
So if your assessments reveal some room for improvement, perhaps it’s worth adding in some aerobic training, however due to its recovery properties I recommend everyone utilise some form of aerobic work, even just 20-30 mins 1 x per week could help. This brings us nicely onto what cardiovascular or aerobic training looks like. For the purpose of this article we are focusing on cardiac output i.e. how much blood your heart can pump around the body or more specifically stroke volume. The more blood your heart can pump around the body per beat, the more efficient it will become, reducing resting heart rate and lowering working heart rates.
The method for this is simple, we want to perform an exercise at a low intensity for an extended period of time. More specifically we are looking at performing the exercise within the 130bpm-150bpm range (the older you are the closer to the 130 range you’ll be) for at least 20-30 mins, but depending on goals can last up to 90 mins. Cycling is one of the best choices, especially if your main goal is strength as running is quite high impact and could still affect recovery. Even working on the pads/bags can elicit the response we need as long as we stay within the heart rate zone above. My favourite is the sled and prowler performed at low intensity. I’ll tell you now, this stuff is boring as hell, especially if you’re used to smashing yourself into the ground on a daily basis and lying in a pool of your own sweat. However ask yourself this, do you still struggle to run 400m during your WOD after years of HIIT? Do you struggle to recover between heavy sets of lifting to the point where you have to sit down for a good few minutes just to be able to get your breath back? Chances are you could benefit from some cardio, yeah that’s right I said the dreaded word……As much as quotes like ‘anything above 5 reps is cardio’ sound cool, you’re doing yourself a disservice if you think you’ll elicit the kind adaptations we are talking about here in this article.
So there you have it, cardio isn’t the killer of gains and can actually help you to get stronger and fitter provided it’s done correctly according to your goals. If it’s good enough for the top athletes in their fields, it’s good enough for us mere mortals and if you’re truly dedicated to performance, you’ll push past the boredom and think big picture on the future gains.