Marion Freijsen A blog about Sports, Fitness & Health

Anaerobic Capacity

Today a guest-post by Coen van Schijndel, fitness expert and trainingscoach. www.topvorm.com

When the aerobic system (meaning: with oxygen) cannot cope, because the effort is too high, the body switches to another system: the anaerobic system.

Anaerobic literally means: without oxygen. Physically, it is the moment that you r body cannot cope with the conversion of glucose from carbohydrates as it has to do so without oxygen. Without oxygen, glucose is transferred with the help of certain enzymes to pyruvic acid.

This is when the burning of glucose, the carbohydrates converted by the body, is done without oxygen which means that different elements are needed. The anaerobic system even ensures that twice as much energy will be released then when you fully convert glucose in the aerobic way. In the first instance this is fairly positive of course, but there is a danger to it – Lactate means the muscle cell’s environment will become more acidic which slows down other processes. The result is a fatigued sense in your muscles resulting in having to slow down your activity or even, in some cases, stopping altogether.

LACTATES

During anaerobic processes, a large amount of lactate is released. This doesn’t mean there is no lactate present during the conversion under aerobic circumstances. There certainly is, but the body can cope with the absorption of the lactate that is released under those conditions. Even when you are resting, the body will have about 0,5 to 1 mmol lactate in the muscles. Lactate has a half-value period of 20 minutes. Meaning that your body will have reduced the lactate present by half in 20 minutes time, when you are completely at rest. With light exercise, the body will only need about 10 mins. to reduce the build up of lactate. This is precisely why a good cool-down, at a low pace, is very important.

LACTATE TEST

Lactate, released during exercise, can be measured. This is done by a lactate test. During a pre-described effort, usually expressed in Watts, a drop of blood is collected at regular intervals. This drop of blood allows you to measure the lactate produced during the effort generated.

This also allows us to measure the aerobic (2mmol lactate) and anaerobic (4mmol lactate) thresholds and the curve and areas between these measures (see lactate curve). In the sample curve of a lactate test the aerobic threshold has been shown to be at a heartrate of 152, and the anaerobic threshold at heartbeat of 163. The aerobic area runs up to a heartbeat of 152, the intermediate area (between aerobic and anaerobic) from 152-163, and the anaerobic area runs above a heartbeat of 163. Beyond this last heartbeat therefore, your body will be faced with excessive production of lactic acid which it cannot reduce.

IN PRACTICE

The heartbeat range in which a mountain bike race will take place, will usually be above the anaerobic threshold. The sample curve shows that the heartbeat of the test person was way above the anaerobic level at 172 heartbeat. Races of a longer duration won’t be ridden so intensively but even so, the average heartbeat of a race lasting two hours, is likely to be above the anaerobic level.

TRAINING

So what does this mean for your training? First of all, you have to tackle the aerobic capacity and then the anaerobic capacity to make sure they are working optimally. The higher your anaerobic threshold, the faster you can ride/run/work out. Even though you will still build up lactic acid, your body can cope with the build up even as you exercise. For a mountainbiker for instance, it is of crucial importance to train anaerobic capacity as you will find during start, finish and on climbs, you will be in your anaerobic range quite often. You also have to train your body in how to cope with and buffer the build up of lactic acid. These are extremely intense training sessions above your anaerobic threshold. Mostly, they will be in the shape of interval training. As you do these with rest periods in between the intense intervals, you can train at a very high level. After each “block” , your body gets a chance to recover. Or you can opt NOT to recover, whereby the lactic acid in your muscles will increase each time you complete an interval. Keeping the legs still (on a bike) after an interval means that the lactic acid produced will stay in the body longer then when you were to cycle slowly. This is a way (but not to be done lightly!) to stimulate your body even further in learning to cope with the lactic acid build up.

NUMBER OF TRAINING SESSIONS RECOMMENDED

As a lactic acid tolerance training is highly intensive, you should never do too many of these session. The average time to recover from such a training is about 48 hours. In addition, your basic endurance will reduce as you train above your anaerobic threshold resulting in you getting out of shape. This can also be the result of doing too many races at a high level of intensity, combined with these interval training sessions. So it is clear that you need to be careful how and when you do these type of sessions. In a build-up phase, it isn’t sensible to do one of these sessions a week – although later on, if you are working up to peaking for a particular race, you can start to do them once a week. However, make sure you get sufficient Recovery time. Training here is “Breaking Down” whereas your recovery results in “Building Up!”.!!