Training intensity - fighting fatigue

Regardless of the sport someone is involved in, the primary goal of every athlete and their coaches is to delay the onset fatigue. The way to do this is by training at specific intensity levels that will stimulate different mechanisms of the athlete’s body.

This week we will spend a lot of time talking about intensity in training and how to use it to our athletes advantage. We will dive into specifics of measuring intensity as well as how much someone should train at different intensity levels.

We will finish it off with a few training sessions with different goals in mind.

Let’s start with fatigue and where it comes from.

Fatigue

To be fast in a race an athlete has to be able to spend a lot of time at or near them limit and sometimes go above it. Where that limit is, is highly individual and needs to be assessed in some way but what is universal is that once exertion becomes too much, the athlete will feel fatigued and they will start to slow down.

There are three primary reasons why fatigue kicks in:

• Buildup of hydrogen ions

• Depletion of fuel

• Failure of muscles

Buildup of hydrogen ions

Just by being alive, our bodies use energy we get from our food. This energy comes from fats and carbohydrates. When carbohydrates are broken down for energy, lactic acid is produced. This in itself isn’t a problem. However, once this lactic acid starts getting into our blood stream, hydrogen ions bond to the lactic acid and create lactate.

Over time, if the body doesn’t remove the lactate, fatigue starts to kick in because the hydrogen ions start to interfere energy production and muscle contractions.

This is only an issue in high intense races like short course triathlons or sprint races so it can be a limiting factor for everyone who wants to compete in this kind of races. Even during long endurance heavy activities, athletes can experience short term fatigue because of surges needed to climb up a hill or follow a group at a certain pace.

The good news is that both the tolerance to lactic acid as well as the body’s ability to remove it more efficiently.

To do this, a lot of short, high-intensity efforts followed by long rests should be incorporated into the training plan.

Depletion of fuel

As mentioned before, fats and carbohydrates are the primary sources of fuel during activities. Fats are used during long and easy activities while carbohydrates, more precisely glycogen is used for fuel.

A well trained athlete can store from 1500 to 2000 calories of glycogen in their liver and muscles and use it during activities.

If the event is too intense or too long and the athlete doesn’t replenish their reserves by using additional foods and drinks they will, eventually, hit the wall and have to stop altogether.

The trick here is to work execute moderately hard workouts without going deeply anaerobic (more on this in the next blog post), and teach the body to conserve glycogen and glucose while becoming better as using fat for fuel. Their muscles will work more economically and use less carbohydrates in the long run which will delay the onset of fatigue.

Failure of muscles

Muscle failure is a little more tricky to define because the exact mechanisms that cause it are unknown, but it’s assumed that it’s related to chemical failure at the connection of the muscles and nerves or serves as a safety mechanism to prevent muscle damage.

Muscles come in two forms - slow and fast-twitched. Fast-twitch muscles contract quickly and need long time to recover. Think of jogging 100 meters vs sprinting 100 meters. Your legs will need a lot more time to recover from the sprint compared to the jog.

The idea is that by training at moderately high intensity some of those fast-twitch muscles will start acting like slow-twitch (endurance) muscles and allow the athlete go go further.

Whatever the reason for fatigue is, athletes are able to raise their levels by a good margin and delay it considerably. This allows them to finish in events faster than before while using less energy at the same time.

Tomorrow we will look at what intensity does to an athlete’s body and how we can manipulate it to the athletes advantage.