What Hikers Should Know About Lactic Acid Build Up

Written by: LindaKennedy

Although it's usually associated with sports like running, lactic acid can also be a problem for hikers and backpackers. But what is lactic acid and why does it cause burning pain in muscles when it accumulates?

When we exercise, we produce lactate in our muscles. Lactate is essential for any movement, it plays a vital role in the production and consumption of energy. At low intensities, this process can continue almost indefinitely, as long as we continue taking on fuel, vitamins and water, we can hike for hours at low intensity.The problems begin when we overload the system. Once our body's ability to handle lactate efficiently had exceeded, we produce lactic acid. Like lactate, lactic acid attempts to produce the energy we need to keep going, but it has a side effect; because of its chemical composition as an acid, it irritates our nervous system, causing pain.

Lactic acid is only produced when the body can no longer keep up with the demands for oxygen placed upon it, and then we switch from aerobic mode (with oxygen) to anaerobic (without oxygen). Exactly when this will happen (when the body switches from lactate to lactic acid production) depends on your fitness. For a highly trained athlete, this lactate threshold occurs at around 85% of their maximum heart rate, which for an athlete like Lance Armstrong is an almost inhuman 180 BPM (Beats per Minute). For a relatively untrained person, the threshold can be as low as 55% of your maximum heart rate; for an average 40 year old, that can be as little as 100 beats per minute. What that means is that every time your heart rate goes over 100 BPM, you will start producing lactic acid.

Unlike steady aerobic workouts, anaerobic workouts produce too much lactic acid for the body to clear; as it accumulates, we experience pain, lose muscle power, and eventually have to stop.

So how do hikers reach these intensities? If we assume that hikers and backpackers aren't running sprints, what sorts of activities can cause you to produce lactic acid? The culprits are likely to include:

• Not warming up

• Not being in good shape

• Hiking lots of hills

• Carrying a heavy pack when not prepared

Let's look at each in turn, see how they can contribute to the production of lactic acid, and what you can do about it.

• Not warming up: The body needs time to ease in to any vigorous exercise. Warm ups are designed to prepare the body for the work ahead by warming muscles, and activating essential processes. One of these is the lactate mechanism. By warming up and easing into a hike, you can prepare the body to efficiently clear lactic acid from the muscles.

• Not being in good shape: Regular exercise, particularly at higher intensities, will train your body to deal better with lactic acid and thus, increase your Lactate Threshold. Over time, you will be able to work harder without "going anaerobic" and producing lactic acid.

• Lots of hills: Lactic acid is produced at higher exercise intensities. Therefore, if your hike includes lots of hills, your body is likely to produce more lactic acid. This doesn't mean you shouldn't hike up hills; it simply means that if you want to control the lactic acid better, you should warm up before you go storming up a hill and that you should get in better shape.

• Carrying a heavy pack when not prepared: Adding weight to your back is a guaranteed way to increase the intensity of a workout. If, however, you are not used to carrying a heavy pack, the chances are: it will stress your body and produce a lot of lactic acid. Be sure to carry a water bottle to replenish fluids. A bit of aloe vera juice on the trail can provide a pick-me-up as well.

If we accept that you can't prevent lactic acid from being produced unless you stay at home on the couch, then how can you reduce it?

There are three steps you can take:

• Get in shape: As we have suggested, getting in better shape isn't just about losing weight or building muscle. Regular cardio exercise and the addition of some interval training will teach your body to deal better with lactic acid.

• Warm up: By building up to the hardest part of your hike, rather than charging straight into it, you will reduce the production of lactic acid.

• Cool down: Finally, by cooling down, you give your body time to redistribute the lactic acid you have accumulated, rather than allowing it to pool in your muscles. This simply means that you will gradually reduce your effort rather than stopping suddenly and do some light stretching at the end of a hike.

By following these steps, you can get in better shape and reduce the muscle burn that hard hikes can produce.

Contributed by:
Dr. Linda Kennedy MS SLP ND

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