Cardio

Endurance Training (Fat Oxidation/Aerobic Training)

Endurance training or “Zone 2” (misleading name) has grown in popularity recently but it's a bit confusing as to how to implement it. The general concept is to build endurance by doing low intensity training, but how do we exactly do that? 

When we do any sort of exercise, our body decides to use carbohydrates or fat for fuel (oversimplified for sake of explanation). Carbs, in the form of glycogen, are usually stored in our muscles (or liver) and are very useful in the initial stages of intense exercise. This is why some people “carb load” before marathons, because the idea is that more glycogen stores means more energy. This is true to a certain extent for up to 90-120 minutes of training, but after your glycogen is depleted, it is very difficult to continue performing. Afterwards, your body has to rely on fat storage to extract the energy you need; if you haven’t trained your endurance, it’s unlikely you will be able to go for longer without risking passing out. 

How do we train our bodies to efficiently utilize a majority of fat (relative to carbs) as energy? This is where endurance training comes in. Basically, training in a zone underneath your “Metabolic Efficiency Point”, when your body is already utilizing fat for energy, trains your body to upregulate fat oxidation (fat burning). Over time, your body becomes better at burning fat, and can do so at higher and higher intensities. This is why endurance athletes can maintain pace for so long - they are burning fat throughout their session, without needing to dip into precious glycogen stores.

How do you find your Metabolic Efficiency Point? You need to do a test with a metabolic cart/chamber. They cost around $200-300 but you don’t really need to test frequently. The learnings from this test significantly changed my training targets and protocol so it was definitely worth it. Here’s one I did in NYC

After the test, you should get some sort of graph like this (below)

I did this test on a stationary bike trainer, which is how I usually do cardio. 

As you can see there’s a small bump where I burn more fat than carbs until the ratio crosses over for good. This is the range I should ideally be training in. You see why this number isn’t really related to a “Zone 2” (implying that it’s part of the 5 zone system). Initially I was surprised by how low intensity this actually was; usually I would train at 140 BPM HR but this was way too high (“Zone 2” content online said 70% of HR so I went with that). The good part is you can easily fit this type of training into your schedule because it doesn’t cause much fatigue, although it does take longer. It’s important to target a general rate of perceived exertion amount (in my case RPE 3.5/10), because heart rate can vary a lot due to a complex set of factors. During this training, you should be able to have a conversation that’s comfortable but not trivial; also your muscles should not build up any soreness or fatigue throughout or after training. 

Endurance training has a ton of benefits. 

• Lower resting heart rate

• Lower apoB and LDL cholesterol

• Increased ability to burn fat, especially during weight loss

• Increased stamina in normal activities

• Prevent diabetes

• Improved mental health

High Intensity Interval Training (HIIT, VO2 Max)

The other type of training that is useful is high intensity training, which mainly improves VO2 max, which is the maximal amount of oxygen you can use during intense exercise. VO2 max is a strong and independent predictor of all-cause mortality. 

These workouts are typically more fun for me because they involve things like sports or just high speed workouts in general. One protocol you can use for this is the 4x4x4 training style where you do 4 minutes of intense work at the highest sustained intensity you can handle, followed by 4 minutes of rest, repeated 4 times. This specific protocol is shown to decrease arterial plaque buildup. I usually do this on the stairclimber, since it’s nice for hiking training. 

Sauna

Including sauna here because it's convenient (already in gym) and has extra benefits if done after cardio. Protocol is 20 mins at 180+ degrees F, as many days as possible. Here are the benefits:

• Improves Circulation

• Improves muscle recovery

• Stress reduction

• Reduces inflammation

• Improves skin health

• Increase white blood cell count, improve immune system

• Lower blood pressure

• Improves breathing

General Exercise Protocol

• Resistance Training: 6 hours per week

• Endurance Training: 3-4 hours per week

• High Intensity Training: 30 mins per week (4x4x4)

• Sauna: 4-5 sessions per week