Sunday, March 31, 2013

Lactic Acid, Intervals, and Threshold Training

It has happened to us all before, we've been on an extra powerful problem or extra long route and our forearms are burning. We're pumped. 

Lactic Acid
Physiologically, when we are pumped, there is an excess of lactic acid within the muscles of our forearms. Our bodies go through several processes to produce energy for muscular movement. One of these processes is called fast glycolysis. During fast glycolysis, the body takes glucose (simple sugar) and breaks down ATP (energy) and pyruvate, a substance that can be used in other processes to make more ATP. 
 As we climb, we breathe in oxygen, that oxygen is then attached to hemoglobin in the blood, the heart takes that blood and pumps it through out body to our working muscles. The oxygen pumped to our muscles is then used to oxidize pyruvate and make more energy. If there isn't enough oxygen in the area pyruvate will turn into lactate. Lactate is a volatile substance and releases hydrogen ions. These ions cause our blood's pH to drop becoming more acidic. This why our muscles burn when we are pumped. 
That burning sensation is uncomfortable, but the formation of lactic acid is bad for performance for two other reasons. Fast glycolysis produces very little energy by itself compared to the body's other energy producing processes, so we aren't being efficient with our bodies' nutrients. Second, many of the enzymes that help the body run well, work optimally at specific pH levels. As our blood pH levels decrease these functions are disrupted.

The Lactate Threshold
The harder or longer we climb the greater the amount of energy and oxygen required to keep us on the wall. As discussed above, if there isn't enough oxygen in the area pyruvate will turn into lactate. The amount of work or exertion where the body can no longer supply oxygen fast enough causing a build-up of lactate is called the lactate threshold. If we continue to perform at an intensity past the lactate threshold we will quickly become fatigued. Lactate can be removed from the blood stream by a process called the Cori Cycle. The Cori Cycle occurs in the liver and converts lactate into glucose to be used as energy again. The only problem with the Cori Cycle is that it is very slow and it takes about an hour for most lactate to be removed.

However, there are several things that we can do to reduce the amount of lactate produced, speed up the Cori Cycle, or increase our lactate thresholds.

Proper Rest
Lactate formation isn't significant until the lactate threshold is reached. If we give ourselves long enough rest between attempts, our bodies have enough time to reset and remove the little amount of lactate produced. According to the NSCA, very powerful exercise i.e. bouldering requires a work-to-rest ratio of about 1:12 (i.e. if you climb for 10 seconds, you should rest from about 2 minutes). As the intensity of the activity decreases, the amount of suggested rest decreases.

Interval Climbing
The Cori Cycle and lactate removal can be sped up by participating in light physical activity, so in our case easier routes or problems. I train using a drill I call Hills and Valleys. For this drill, pick two ratings of climbs with a good difference in difficulty i.e. V1 and V5. Pick a random sequence of nine problems, with at least 3 being the high rating i.e. 
Attempt this sequence with as little sitting/standing rest as possible. The lower rating problems should be the rest.

Threshold Training
Threshold Training is the most intense technique out of the three discussed. During threshold training the climber climbs a route or problem that is right at their limit, but they know they can do. The climber times their attempt and then rests for as long or shorter than it took them to climb the route and then repeats the process until fatigue. By not giving the body time to properly rest between attempts the body must make adaptations for future training sessions i.e. a week away. The body "learns" to store more glucose, glycogen, and enzymes in order to maintain these demands. I have developed a threshold timer, that subtracts certain amounts of time from the rest period. The timer should work offline for most browsers so you can bookmark the page and use the timer at the gym or even outside on a smart device. 

**Couple of notes about Threshold Training**
Threshold Training is very taxing on the body and it suggested that this type of training be limited to only 1 to 2 training sessions a week. Be smart about this, if you notice any pain or a significant decrease in technique during the drill stop immediately to prevent injury.
Second, the Threshold Training protocol used at lower intensity can be very beneficial at learning how to pace oneself on very long routes and problems.