“Increased aerobic capacity leads to improved tolerance of all bio motor abilities” – Charlie Weingroff
As I spend more time working on my aerobic fitness I fall deeper and deeper down the rabbit hole. For a long time, I believed that an aerobic base was not important and that I could just do a few high intensity intervals as I got closer to my event or season. I thought strength was the key to everything. I also was constantly injured, slept poorly and gassed out very quickly, even on the fire ground – despite being a guy who worked out constantly. Now, I’m not saying that taking the time to work on my aerobic fitness and shifting my focus from constantly crushing myself has been a cure-all but I certainly sleep better, recover quicker but most importantly I can push myself for far longer than ever before. Here’s why:
The heart adapts to exercise – of course. How the heart adapts to different forms of exercise is something most people are not aware of. The left ventricle wall responds differently to different stimulus. At heart rates below 150 beats per minute the left ventricle will respond with eccentric hypertrophy. At heart rates above 150bpm the left ventricle will respond with concentric hypertrophy. What does this mean?
Eccentric hypertrophy as it pertains to the heart means that the cavity is enlarged, while concentric hypertrophy results in a thicker ventricle wall. Both things are good – but at the right times. At heart rates between 120 and 150bpm, blood completely fills the left ventricle, allowing it to stretch to its full capacity which results in a larger cavity to pump blood. A larger cavity results in a greater stroke volume (how much blood will be pumped each beat). A greater stroke volume results in a lower resting heart rate due to a greater supply for the same demands. If you haven’t figured it out yet, a lower resting heart rate is a good thing. More on that to come…
On the other hand, at heart rates above 150, when we are demanding a lot more power from the cardiovascular system we see concentric adaptations. This will result in a thicker heart wall and increased strength with each beat and a higher concentration of mitochondria within the cardiac muscle. Greater strength and more cardiac mitochondria are beneficial during periods of sustained, high heart rates, when the demand on the cardiovascular system is higher. More mitochondria in the cardiac tissue will allow the heart to beat stronger and for longer.
Both types of hypertrophy are important but generally, especially as of late, we see people exercising in the higher intensity range. To be clear, I’m not hating on high intensity intervals. I just believe we put such an unnecessary premium on them. They are certainly effective for fat loss and play a very important role when training for intense events but most people could afford to spend some time training at relative lower intensities – such as those that participate in team sports and especially any police or fire personnel. We spend so much time stressing our bodies and placing our nervous system in a sympathetic state that we could use some time dedicated towards returning our body to a parasympathetic state, returning to a rest and digest state.
By building an aerobic base you increase your ability to remain in aerobic metabolism at higher power outputs (you can last much longer when you’re working aerobically). You are also able to shift your body back to aerobic metabolism quicker between bouts of high intensity work by metabolizing anaerobic biproducts, allowing the body to return to a high output state quicker. The three energy systems can be thought of as a triangle. The aerobic system makes up the base, the next step is the lactic system and the peak is the ATP/PCr system. If we increase the size of the base, then we can build up the next two systems higher – resulting in increased endurance across the board. You must train the lactic and PCr systems as well, but these systems will see adaptations very quickly, because they do not possess the same capacity for growth as the aerobic system does. Any team sport athlete with a reasonable length offseason would benefit from spending time specifically developing the aerobic base and peaking with the other two systems at the right times closer to competition.
Here are 3 ways to start to develop the aerobic base.
Cardiac Output Method
This method can consist of literally any activity that does not raise your heart rate too significantly. The key to this method is keeping your heart rate between 120-150bpm for 30-90 minutes. You will generally see the most benefits when you spend more than 45 minutes, although realistically some people only have the 30 minutes and that will be just fine if that’s what you have. It is important to note that your heart rate does not have to remain constant the entire time. You can fluctuate between the high and low ends of the range. Some specific examples for this type of training would be:
-Walking at a brisk pace
-Walking on an incline (also great for recovery during heavy strength training phases)
-Jogging (if you can do it slow enough, this is where the term “road work” comes from)
-Mobility/torso circuit (pick 6-10 exercises such as planks, active yoga poses or body weight exercises and complete non-stop for your allotted period of time)
-Low level medicine ball tosses or running mechanics
-Pushing/pulling a sled (keep the weight light enough that you don’t gas out or raise your heart rate above 150)
These are just a few examples and this type of training should make up 1-3 workouts per week during the initial general endurance phase. This method will be very effective at increasing stroke volume and should be a primary focus if your resting heart rate is over 70bpm.
This method was used successfully by track coach Charlie Francis. He would have his sprinters complete 10-15 second repeated sprints at 70% effort as a way of improving their fitness levels without logging unnecessary miles. Rest intervals should last about a minute and the heart rate should return to 130bpm or lower. This method does have to be limited to sprints, you can use any form of exercise so long as about 70% effort is achieved and the heart rate remains under anaerobic threshold (around 165bpm for most people). To use this method as a recovery tool complete 15-20 repetitions but to use it to increase fitness and train the aerobic base 20-30 repetitions should be completed. This method will yield similar results as cardiac output training and can also be completed 1-3 times per week.
This method is quite simple but often gets overlooked. It involves modifying your tempo on strength exercises. Tempos should be a minimum of 202 but can also be 302 or even 303. This mean that each rep should be completed over 4 seconds or more. That’s 2 seconds down, no pause followed by 2 seconds up. You should choose exercises that train large muscle groups such as squats, rows, bench press or pushups. The reason this method is so effective is that the slow tempo targets the slow twitch muscle fibers resulting in significantly larger slow twitch fibers. Increased slow twitch fibers can oxidize anaerobic bi-products created by the fast twitch fibers thus increasing their ability to sustain power output. This method should be used once per week for 3 weeks, taking the next week off from this method.
None of these methods are overly difficult, taxing or complicated but they will deliver huge results. Each of these methods will be a good start and should make up the bulk of your training when designing your general endurance phase. They can be used on off days when the training intensity ramps up later in your annual plan. These are also very simple methods to start using if you are just beginning an exercise program, whether for the first time or restarting. Give 1 or 2 of these methods a try for a few weeks and record your resting heart rate in the morning daily to track the changes. You should end up with a lower waking heart rate as well as feel more refreshed for your training.