Monday, March 19, 2012

Delayed Onset Muscle Soreness

What is soreness and what causes it? Nobody likes being sore, but everybody who has done a new workout is familiar with it. I have often heard that it is caused by the buildup of lactic acid in the muscles. For the longest time I have thought this was correct. Technically I am a scientist so please indulge me for a bit as I wax scientific.



If we think back to our biochemistry class in college we'll recall that lactic acid is produced when insufficient oxygen is available for complete oxidation of glucose to pyruvate. Instead, lactate is produced and accumulates until oxygen levels increase such that lactate is converted to pyruvate and fed into the Krebs cycle. The transient build-up of lactate produces pain often referred to as "the burn." The muscular exhaustion associated with "the burn" is caused by reduced ATP levels resulting from the lack of pyruvate which feeds the Krebs cycle. We have all experienced this as we have failed the final push-up or sit-up or barbell curl or whatever of a long set. Anyone who has done rock climbing remembers their first day at the climbing gym feeling their forearms burn and watching their grip loosen as they fall down onto the crash pads. Shortly after the work (lifting weights or climbing) has ceased "the burn" goes away and some strength is returned. The soreness is gone.



The reason I bring this up is to point out the transient nature of the lactate induced soreness. The depression in pH, due to lactate build-up, induces a very normal painful sensation that tells you to stop what you are doing. Once you stop doing that painful exercise the lactate is rapidly converted to pyruvate (which is shuttled to the mitochondria where it enters the Krebs cycle) which raises the pH to normal levels and the pain is therefore lessened immediately.

If lactate causes pain but is clearly removed shortly after a particular exercise is completed what causes delayed onset muscle soreness (DOMS)? Now when I refer to DOMS I mean the debilitating soreness that occurs 24-72 hours after a workout. Upon surveying physiology textbooks it turns out there is not one particular substance to blame for soreness but many. In fact so many substances are to blame that textbooks don't list them they are just covered under the blanket term inflammation. When you do a new workout that you are unaccustomed to a great deal of damage is inflicted on your muscle cells and widespread inflammation occurs. The pain (sometimes severe) derived from DOMS comes from the accumulation of a variety of metabolites that your body can't get rid of rapidly because it is busy repairing damaged tissue.

So while I was looking into all of this I had a thought about proper training programs. Soreness is often confused as a sign of a good workout. If your program has your musculature in a chronic state of inflammation and disrepair you have to ask yourself, is this a good program? Should I really be in pain all the time? I say no and no. A good program shouldn't make you feel like you have been beaten badly. A good program should also allow for recovery so you can improve in performance.

DOMS occurs when you do somethings drastically more stressful than before. I have been following the starting strength program for about 6 months. I have doubled my bench press and press numbers, tripled my squat and added nearly 200 pounds to my dead-lift. These are significant increases but have occurred over an appropriate amount of time. I have been significantly sore three times during my recent training. (1) When I first started lifting weights, (2) when I came back from a month lay-off due to ankle surgery and illness, (3) and when I stretch my bad ankle a lot. This shows (I hope) that progress does not have to come at the expense of chronic pain. I don't mean to advocate people being wimpy and not pushing themselves. I do mean to advocate the use of intelligent and sound training programs. Not one based entirely on silly pseudoscientific principles like "muscle confusion."

The body learns to repair itself quite quickly. The first time it is stressed it has a hard time. After the initial blow, if you feed it and stress it properly, you can progress and need not be forever sore.

5 comments:

  1. This reads like an interesting column in Runner's World or other magazine. Keep up the good work. It's interesting how the pieces fit together.

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  2. I totally agree with you bri. I started a new job in the hospital where I draw and analyse arterial blood gases and electrolytes. There are many factors that raise the lactate levels in your blood(most are medically induced). But these high lactate levels are quickly metabolised within a few hours. And the inflammatory response takes place in any body tissue that is overly stressed. The good thing is that muscle tissue is extremely resilient when compared to other tissues. Good work Brian most everyone attributes soreness completely to lactate buildup, when about 40% of pain and soreness your body experiences results from inflammation of one kind or another.

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    1. I have actually heard (not read) that lactate is important in healing processes. So if a muscle is injured (torn) continuing to work it, albeit lightly, will help it heal better with less scar tissue than just laying off it. The point is lactate gets a bad rap. It is actually a very useful highly transient metabolite.

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  3. Hey I have heard a theory. After a workout to submerge the exercised muscles in a ice bath. What has been explained to me is that the blood in the exercised muscles will travel to vital organs taking with it the lactic acid and then will be replaced with new blood cells.
    Good article. I have experienced DOMS many times and like you it always comes after long bouts of idleness.

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    1. Icing is a good idea. Competitive weightlifters do it all the time. Remember it is the inflammation we are concerned with not lactic acid. Muscles are highly vascular and the lactic acid is rapidly metabolized so it isn't a problem. If you train hard like a weightlifter icing will eventually be necessary for recovery.

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