The sting of hard work - delayed muscle soreness

During spring quarter, the most popular question I was asked was to avoid or get rid of muscle soreness after working out? A lot of times, I like to ask them what they think rather than telling them the real cause of it and all of them answer in the same fashion: lactic acid buildup. Little do they know that's really not the cause of delayed muscle soreness, and hopefully after this post the misconception will be cleared up. 


What lactic acid, or really lactate, really is is a molecule that's been converted from pyruvate during anaerobic glycolysis. I know this all just sounds like scientific nonsense right now, but let me first explain some basics on human metabolism and how the body produces energy.

First, the body needs ATP (an energy molecule) to carry out everyday metabolic and physical activities. There are two ways that the body generates ATP, through aerobic or anaerobic glycolysis. Aerobic simply means that this pathway requires oxygen whereas anaerobic does not require oxygen. The aerobic pathway produces a much higher yield of ATP, therefore making it the most effective and efficient method of energy production.


In order to undergo an aerobic pathway, there must be enough oxygen delivered to the site of activity. For example, while you are jogging or swimming, you breathe must more frequently therefore delivering enough oxygen to those muscle cells. With that oxygen, the pyruvate (originally glucose) is converted into acetyl-coA. The acetyl-coA is then broken down further into a very high yield of ATP molecules.

Now if you were to lift weights or sprint, the body hardly breathes therefore it does not deliver the sufficient amount of oxygen to your muscle cells. Without oxygen, your body converts the pyruvate into lactate. Lactate therefore is broken down into a much smaller yield of ATP.

Lactate production continues for 1-3 minutes in which it builds up in high concentrations in your muscle tissues. This high concentration increases acidity in your muscle cells, making it a poor environment for ATP production (explaining why it generates a smaller yield than aerobic pathways). 


Lactate provides a temporary burst of energy in order for you to finish that last rep or last few meters of your anaerobic exercise to prevent your muscles from giving out and causing severe or permanent muscle damage. Lactate also causes that burning sensation during your workout, not afterwards. That signals you that you should ease up on that particular muscle and allow 24 hours to let that muscle relax and clear out the high concentration of lactate. Without that burning sensation, there is no indication that your muscle will give out on you therefore increasing chances of muscle damage. 


There has not been any research to support one, solid explanation as to what causes delayed muscle soreness. However, the most popular theory is "microtrauma", in which your muscles experience microscopic tears in its fibers. These tears cause inflammation and an a build up of red blood cells and white blood cells to try and heal the tears. The inflammation also causes swelling of the muscle cells and subsequently causes soreness. The image below shows the most common sites of muscle tears after an intense workout.

 wikipedia.com

Don't worry, I didn't forget what the original question was. The best way to avoid soreness is to stretch before and after your workout and to rest each muscle for at least 24 hours. If the microtrauma theory is true, then my advice to stretch before and after a workout would be highly beneficial because stretching allows for the muscle to be less rigid and stiff and therefore less susceptible to these microscopic tears. 

Hopefully all this information cleared up some misconceptions. If you want a better explanation of the metabolic pathways I've found these two websites to be really helpful (I'm sure you'll recognize one of these sites from your high school days).


http://www.doctorsexercise.com/journal/aerobic.htm

http://www.sparknotes.com/biology/cellrespiration/glycolysis/section3.rhtml

Don't let the soreness of exercising discourage you from continuing your regiment. In fact, studies show that exercise has direct correlation to overall mental and social vitality. Read this blog if you need a few more reasons and words of encouragement to get back on that bench or treadmill at the gym.


http://www.livestrong.com/article/154524-problems-college-students-face-when-they-dont-exercise/