High Intensity Training for Strength and Cardiovascular Improvements
By: Aaron Schneider BS
What is high intensity training (HIT)?
HIT is a form of weight lifting that is done with maximum force output for a short duration of time (about 90 seconds) that takes you to momentary muscular failure. While this may sound scary, it is done in a slow controlled manner which minimizes risk of injury and maximizes efficiency. There are five basic movements involved (leg press, chest press, row, shoulder press, and lat pull down) and the workout only needs to be performed once a week (if performed properly to momentary failure). It is also possible to do single joint movements, but it is important to start with the complex, multi-joint movements. It is a safer form of exercise than doing the repetitious movements involved in typical “cardio” like running, and safer than the high speed ballistic movements involved in the newly popular Crossfit workouts. High intensity exercise helps improve all bodily functions; from strength and cardiovascular systems to insulin sensitivity and blood sugar regulation. It helps lower our heart rates, reduce blood pressure, and increase the chemicals that make us happy. Today we will focus on the strength and cardiovascular systems, which together can be labeled as overall fitness or endurance.
Why and how does HIT work?
HIT utilizes our body’s natural survival mechanism to create muscle strength and endurance. The human body is made up of trillions of cells whose only design is to undergo cellular metabolism and survive long enough to pass on their genetic code. If our cells think they are going to die they will adapt so that the next time they encounter that situation they will be stronger and more efficient. This then translates to the whole body. As we take our muscles closer and closer to failure our cells begin to panic. Our ancient survival mechanism kicks in and then we begin to panic. When this happens we want to stop because if we keep going to failure that big predator or human rival will have overtaken us and we die. 10,000 years ago we lived in a world of big predators and humans from other tribes that may have wanted to kill us. With the proper coaching and motivation we can continue pushing through this sensation for a few seconds until our muscles completely fatigue and then we stop. During this process we recruit as many muscle units as possible and this muscle tissue is broken down in the process, our energy levels (muscle glycogen stores) are depleted, and our respiration and heart rate increase. But we are still alive. What happens on a very basic level is the cells realize that first they have to repair the damage done, then they must build more muscle and become stronger and more efficient so that the next time we encounter this situation we do not come so close to dying and our chance of survival increases. The response leads to increased strength and increased overall fitness.
In order to understand the cardiovascular adaptations we must first understand some basic cellular metabolism. There are two basic energy-producing pathways: the anaerobic and the aerobic pathways, known as glycolysis and the Krebs (citric acid) cycle respectively. [Aerobic meaning with oxygen and anaerobic without oxygen]. The anaerobic pathway starts with glucose and through a series of chemical reactions produces ATP (energy) and a waste product known as pyruvate. Pyruvate is better known by the product it transforms into, lactic acid. If there is enough oxygen present the pyruvate enters the aerobic pathway within the mitochondria to allow for further production of ATP. The aerobic pathway also produces much more ATP than the anaerobic pathway; about 9 times more. [And this is just for sugar. Our body produces close to 130 ATP per fat molecule].
Now, when we think of weight lifting we think of the anaerobic system working, and when we think of “cardio” or aerobics we think of the aerobic system being the primary energy-production system. But this is in fact not the case. Both systems are working all the time. The difference between high intensity training and typical “cardio” training is the degree to which each system is stressed. During bouts of “cardio” the anaerobic system is not being greatly stressed and there is always enough oxygen to allow for the aerobic metabolism to take place. However, during high intensity training where a lot of energy needs to be produced in a short period of time, the anaerobic system is running so fast that it produces more end product (pyruvate) than the aerobic system can cycle. Pyruvate builds up in the cells and converts into lactic acid and this creates that muscle burn. Because the aerobic system (which produces 34 ATP) cannot work any faster, and the anaerobic system (which can only produce 4 ATP; not nearly enough to fuel the high intensity workout) is getting backed up, we quickly reach that momentary muscular failure. The muscle cells fatigue sequentially because there is no rest involved. Thus, high intensity equals short duration. During “cardio” however, we can continuously move because we are working at a lower intensity and not creating this backup in the cell. We can continuously produce enough energy to go for hours. The problem with this is that it takes a lot of exercise to create the ideal adaptations and the movements are repetitive; this is where chronic inflammation and chronic injuries start to happen, such as shin splints and stress fractures. On the other hand, when doing high intensity exercise, the glycolytic system is being stressed beyond its capacity. When we finish the exercise, the lactic acid that was built up gets cycled through the liver and comes back to the cells as pyruvate. Now that the exercise is over and there is plenty of oxygen available, the cells undergo aerobic metabolism. This means that not only did we get a tough workout in a short time period we also got a workout for 1-2 hours afterward while we were relaxing or lounging around, and we got the same cardiovascular adaptations as “cardio”.
All things being equal, high intensity exercise may be the superior style of exercise for your health, but if you truly enjoy running or cycling or any other form of “cardio” by all means do it. It all comes down to the fact that it is your choice how to exercise. If you like the idea of not having to work out all the time and you like having plenty of time in the day and week for other activities, then high intensity exercise is your best bet. But if you like getting out for a few hours to get away from everything, or you enjoy sweating for a couple hours in the gym doing circuits, then do that. For those that enjoy the latter I still recommend incorporating high intensity training into your life. The nice thing is that you can schedule the training around your life as opposed to having to schedule your life around the gym or hours of working out every day. Ask yourself, “If I choose high intensity training, what can I accomplish with all the extra time I have saved?” Weigh the pros and cons, the benefits and costs, and make sure you are having fun.
Aaron Schneider runs the CSI Performance Lab and is in charge of setting up rehab and training programs. “At CSI our job is to get you back to performance level” He can be contacted through CSI website, www.gotcsi.com