Why go low? Low Intensity Training and Fat Usage

Let me begin my first column with a one question pop quiz. True or false: the best way to train for motocross is by 1) Doing hard motos and 2) Running or cycling as hard as you can for slightly longer than the length of your race motos. If you are old-school or new to training I bet you say true. Unfortunately you are wrong. If you’ve educated yourself on training more than the average person, I’m sure you say false. However, my aim with this article is to explain why that statement is false.

I need to emphasize that hard motos and intense cross-training sessions are a key component to a motocross training program. However, they are only a piece of the puzzle that is “Motocross Fitness”. Other pieces of this puzzle include sprint laps, technique work, strength training, power training, muscular endurance training, flexibility training, high intensity or interval training, mental training, proper nutrition, and rest and recovery. One additional component that is absolutely vital but often forgotten or ignored is low intensity training. Often called long slow distance, this type of training involves working at levels much lower than you would exert in a race situation. The average motocross racer likely thinks to him or herself “How is going slow going to make me go fast?” The answer to that question has multiple parts.

First, it is important to understand the way the body produces energy from the food we eat and the stores in the body. Basically, there are means through which the body produces energy and each has its own positive and negative. The first system is the phosphagen system which is the fastest way the body produces energy, but unfortunately it only lasts about 10 seconds so it isn’t too relevant to motocross. The other two, aerobic and anaerobic metabolism, are vital to motocross, and both need to be trained. In short, anaerobic metabolism, also known as the lactic acid system or glycolysis, occurs when energy is made from carbohydrate without the utilizing oxygen. Anaerobic metabolism has the advantage of being quick but it only produces limited amounts of energy. In terms of ATP, which is basically a unit of energy, one glucose molecule produces 2 ATP during anaerobic metabolism. In contrast, the aerobic system can use carbohydrate or fat to produce energy when utilizing oxygen. This is a slower system however it produces much more energy. For instance, one molecule of glucose produces 36 ATP. When fat is the fuel for aerobic metabolism, the process requires one more step and is the slowest yet, however one molecule of fat can produce 460 ATP.

Now with the basic understanding of the body’s energy systems, you can see that fat produces much more energy per molecule than carbohydrate. In addition, the human body has much more fat stored than carbohydrate, even in people who are thin. These two factors make it obvious that fat is the fuel of choice for events long enough in duration to utilize it. However, during high intensity exercise, the body can not keep up with its muscle’s energy demands using only fat as fuel. Yet, with training, the body undergoes many changes that allow it to utilize fat more. Its also important to note that the more the body can use fat as fuel, the more carbohydrate stores are left in the musle to fuel the high intensity activities when energy is needed quickly, like when you have to ride a little harder to make that late moto pass.

So, how do you teach the body to use fat as fuel? Hopefully you guessed low intensity training. Low intensity training done for adequate time stresses the body and causes it to adapt in multiple ways. One of the changes that occur is the number of small blood vessels or capillaries increases in muscle. This is an attempt for the body to supply the muscles with more oxygen and fat, the key components in aerobic metabolism. Also, the muscle cells themselves develop more mitochondria which are the factories inside the cell where energy is made. Likewise, the body learns to produce the chemical and electrical signals that trigger aerobic metabolism of fat more quickly. Moreover, low intensity training encourages the body to produce more of the enzymes and other chemicals necessary to convert fat into energy.

So now that you know how low intensity training benefits your performance, it is important that you know how to effectively utilize low intensity training. If you know your 5 heart rate zones, this form of training is basically Zone 2. For the average motocross racer to elicit a favorable response, he or she needs to spend between 1 and 2 hours in Zone 2. The number of workouts done in this zone depends on whether it’s the preseason, or the in-season. Ideally, the preseason is used to build a “base” and will consist mostly of Zone 2 training. Low intensity training is done throughout the in-season, but it is done in much smaller volumes so that time can be dedicated to high intensity and speed work as well. Low intensity training can be done via any normal means of exercise but road cycle is usually considered the easiest. Additionally, it is important to note that low intensity training should also occur on the motorcycle. Trail riding is an excellent way to accomplish low intensity training that applies directly to motocross. It’s a great way to have fun as well.