The whole point of using different heart rate zones when training is that each training zone has a different effect on your fitness. It is worthwhile taking the time to understand the benefits of training in each zone.

The value of each training zone should not be underestimated and although it may feel strange the first time you do a run  at 65% (because it doesn’t hurt and you’re not sweating like a pig), resist the temptation to push harder and just keep at it, it’s on your programme for a reason.

The Energy Efficient or Recovery Zone – 60% to 70%

Much of the benefits from heart rate training involve the body’s energy systems and one of these systems is responsible for the long term supply of energy to your working muscles.

Fat is an abundant source of energy for the endurance athlete. Training within this heart rate zone – best accomplished by doing long, slow runs – develops the body’s ability to feed the working muscles more efficiently.

The other major advantage to training in this zone is weight loss, because you are almost exclusively burning FAT. You will also be allowing your muscles to re-energise with glycogen, which has been expended during those faster paced work-outs.

Underestimate this training zone at your peril.

The Aerobic Zone – 70% to 80%

When you train in this Heart Rate zone, you are training your cardiovascular system. Within this range, the body’s ability to transport oxygen to, and carbon dioxide away from, the working muscles can be developed and improved.

As you become fitter and stronger from training in this zone you will get the benefits of some fat burning and improved aerobic capacity. 75% training often feels good.

This zone is also ideal for developing local muscle strength.

The Anaerobic Zone – 80% to 90%

This is the zone in which an enormous amount of benefit can be gained.

Somewhere between 80 and 90%, your individual anaerobic threshold is hiding. Between these heart rates, you use very little fat, instead you start to use glycogen – which is stored in your muscles – as the main source of energy.

Unfortunately, one of the by-products of burning this glycogen, is our worst enemy, Lactic Acid.

There is a point at which the working muscles are producing lactic acid at a faster rate than the body can remove it. The heart rate this happens at, depends on you as an individual but when you do hit this point – known as Anabolic Threshold it will be accompanied by a rapid rise in heart rate and a slowing of your pace – sound familiar?

Through the correct training it is possible to delay the Anabolic Threshold either:

  •   by increasing the heart rate at which you reach it or
  •   by increasing your body’s ability to deal with the lactic acid for a longer period of time.

Sometimes elite athletes can hold a pace above their AT but for most mere mortals “going off too hard” will only result in you “blowing up” half way through a race/run – something most of us have experienced at some stage, and it’s not pleasant.

This article explains the newer way of thinking that it is actually hydrogen ions that cause us to have jelly legs not lactic acid build up. The cause of your muscle fatigue is actually the result of a buildup of hydrogen ions. For each lactate molecule produced by the body, one hydrogen ion is also formed. Hydrogen ions lower the blood pH and make the muscles acidic. This acidity irritates muscle nerve endings and causes that pain, heaviness, and burning mistakenly attributed to lactic acid.

Recent research indicates that the goal of endurance training shouldn’t be to reduce the production of lactic acid but to improve the ability to clear lactate from the blood. Simply speaking, we shift from the idea of increasing our tolerance for lactate production to the idea of increasing how efficiently our body utilizes lactate as an energy source.

The faster we can train our body to reconvert lactate back into energy in the liver, the longer and faster we can run at a given pace. Therefore, the goal of your lactate threshold training shouldn’t be how to reduce lactic acid production, but instead to train your body to use it efficiently. While this shift in thinking is slight, it radically changes how you approach your lactate threshold workouts.

The Red Line Zone 90% to 100%

In this zone you will only be able to train for short periods of time. It effectively trains your fast twitch muscle fibres and helps to develop speed.

It is worth being aware that to develop this speed you must first have developed your ability to clear lactic acid from your system.

This zone is reserved for racing sprints and only the very fit are able to train effectively within the red line zone.

Remember, training very near your maximum HR can be dangerous.


Use this link to work out your heart rate zones: