Endurance Training

            Swim, bike, run… injury? Unfortunately this trend is all too familiar (and hardly desired)! To make matters worse, most triathletes tend to accept this, and even expect it to happen at some point throughout the season. The vast majority of such injuries are due to overtraining. As an Elite Triathlete and coach my job is not to push, but to hold back.  Having a sound training philosophy is thus more important than most think. My intent in this article is to discuss high/low training, with an emphasis on the Central Nervous System (CNS). High/low training is very common, usually deployed in weight training. It is important to know that it can be expanded and used to keep endurance athletes healthy as well.

            First, I would like to discuss the CNS as it relates to training. Muscles are not much more than hunks of meat, with brilliant ability to move the human body through space. The muscular system is the brawn, and the CNS is the brains of the operation (no pun intended.) The brain, and accompanying nerves, determines which muscle fibers fire, and with what intent they fire. Aside from movement, the main purpose of the CNS is to reduce threat and keep us out of harm. It does this by controlling our bodily systems, including the muscular system, in such a way that anticipates a threat and acts accordingly.

            An ectodermal (nervous system) approach to training is much different from the norm. Take a full out sprint for instance. We can hold full speed for around six seconds. Slowing down during a sprint does not occur due to a lack of readily available ATP, but because our brain has slowed us down. A full out sprint is perceived as a threat, especially the longer that it lasts. The brain believes that we will tear a muscle, break a bone, or worse. Therefore, threat reduced. This is accomplished by the perceptions that the brain sends around the body. Legs get heavy, breathing is deep, and we feel as if we may pass out. These are all OUTPUTS of the brain, not INPUTS from the body. The body does not tell the brain it is sore, the brain tells the body to be sore. Next, let us look at a simple hamstrings stretch (barring injury/facial tension). As you pass into a greater range of motion, the brain senses a threat. The muscle or tendon may tear. A tightness, or “stretch,” occurs, thus limiting ROM. This is apparent when the body is unconscious, as when undergoing surgery. ROM increases exponentially and a person becomes very flexible. In this state the CNS’s inhibitory ability is nullified, making it unable to cause the tightness that limits ROM.

            After a training session, muscle soreness is felt. This is simply another output of your brain. The CNS is trying to keep you safe. The feeling of sluggishness that follows is due to the activity of your CNS. Yes, that is right you can fatigue your nervous system. In fact, a chronically fatigued CNS is the main cause of overtraining and eventually injury. When your CNS is asked to do its job at a high level, it becomes fatigued and needs to properly recover. This is where the high/low training principle comes into play.

A CNS intensive training bout is one that is above 75% of exertion. The closer to 100% exertion, the more profound the stimulus to the CNS. Some examples are: max effort lifts, sprints, and threshold intervals. I often explain them as any session that puts you into the red. In general, a CNS intensive bout takes around 48 hours to recover from.

            The sole purpose of “hard training days” is not to get stronger or faster, but to pull some slack from your CNS. On such days, you push to the limit. Your CNS is there to pull back on the reigns by making you feel tired, or ready to throw up and pass out. This is a threat reduction by your brain. Once you have completed the session and your CNS sees that you have not suffered serious injury it becomes a little more accustomed to the stimulus. Next hard day, you will find that you can go a little more. These type days are very important to training, but they are even more important to properly recover from. If CNS intensive stimuli are too close together the recovery process will be compromised and progression stunted. 

            How do you recover from high training sessions? This is where the Low part of the philosophy comes into play.  Low-level training (under 75%) will aid in the recovery of the CNS. Along with recovery, low-level fitness (LLF) can be increased via low-level sessions. LLF is extremely important to all sports, and is often undertrained in top athletes. Some examples of low-level sessions are: easy cross training, tempo work, or light lifts. Basically, anything that causes light sweating.

            I do not intend to write a training program here. Every athlete is different and will need to alter specifics. I do, however, recommend that these training parameters be taken into consideration when scheduling. Hard days usually contain one, sometimes two, hard training bouts. The next 48 hours are spent in the light training mode, working on recovery. A strong concentration on low intensity days is recommended. Increasing intensity/duration should be gradual.

            I believe that what I have outlined is the best and safest way to train as a triathlete. As I have stated before, this is a training backbone, and must be adapted to each individual. Many triathletes spend too much time training at high intensities and do not allow the CNS to properly recover. Remember, just because muscle soreness has subsided does not mean the CNS is ready to go. Many times the sluggishness that I alluded to earlier is disregarded and high intensity training is done too early.  Also, low intensity days must be just that, low-level. If done properly, High/low training cycles will increase desired results due to health of the CNS.