Lactic Acid is the byproduct of metabolism. When too much lactic acid accumulates in the bloodstream, fatigue sets in. This fatigue is essentially a temporary inability to deliver oxygen effectively to the working muscles.
The body's ability to metabolize (get rid of) lactic acid, often called the lactate threshold, can improve through training. For unfit individuals, this lactate threshold could be be very low (60% of maximum heart rate) whereas for very fit endurance athletes it could be very high (up to 90-95% of maximum heart rate). Most of us should aim to have a lactate threshold at 85% of maximum heart rate or higher.
The best way to improve your tolerance for lactic acid is to do high intensity interval training, or HIIT for short. What this means is that you should perform intervals of 30-180 seconds where your heart rate is elevated to the highest level possible without causing total exhaustion.
You can wear a heart rate monitor or you can use the RPE (Rating of Perceived Exertion) scale of 1-10 to measure your workload.
To calculate your age-predicted maximum heart rate, subtract 220-Age and then multiply this number by 80-90% to determine where your intervals should be. If you don't want to use heart rate, shoot for an 8-9/10 on perceived exertion with 10 being total exhaustion. There are an infinite number of ways to structure HIIT, but try to do 5-10 intervals of 30 - 180 seconds with about the same amount of time recovering as the intervals.
Some good ways to incorporate HIIT into your exercise program are rowing machines, walking hills, sprinting, boxing, jumping rope, swimming, or other types of running drills.
I just finished an excellent book on the topic, appropriately called HIIT.
The unique benefits are numerous:
- Recover Faster Between Intense Bouts of Exercise
- Burn More Bodyfat during and After Exercise
- Overcome Insulin Resistance by training the body to use Glycogen More Efficiently
- Intense Release of Endorphins (make you feel good, euphoric, and feel less pain or sadness)
Let me know if you have specific questions.