While many think fatigue and soreness is caused by the accumulation of lactic acid this is an old myth that hasn’t died.
Lactic Acid
For energy, our muscles use glucose and glycogen during exercise. When these energy sources are broken down, our body produces what is called lactic acid. This acid is the “burning” sensation felt when working our muscles, which can also be attributed to low oxygen levels in the muscle, as well as the recruitment of fast twitch fibers. Removing lactic acid from the blood may be aided by performing a “cool down” immediately following exercise. Research indicates that lactic acid levels in the blood return to normal within 40 minutes of a cool down, as opposed to 60 minutes without.
Lactic acid, however, is not the reason you are sore after intense exercise. Muscle soreness is something that effects us a day or two after a heavy bout of activity. This is referred to as DOMs or, delayed onset muscle soreness. DOM’s in actuality is a type 1 muscle strain associated with pain that restricts movement. Pain varies from light to severe stiffness (Braun).
What is soreness
Soreness is the result of the breaking down of muscle proteins. Muscle fibers are torn during contractions that produce high force. An inflammatory-repair response is initiated, which is responsible for the pain, tenderness, and immobility of the muscle (Kenney).
The body is not used to performing muscle-lengthening exercises. Because of this, eccentric movements cause more damage than concentric movements (Kedlaya). Due to fewer motor units being activated during eccentric than concentric contractions, force is spread over a small cross-sectional area. This increases tension per unit. Therefore, soreness will be much greater following eccentric movements than concentric.
Whether it is that the structural elements of the muscle fibers are disrupted, or the connective tissue is yet to be proven as the causation of DOMs (Braun).
Tips
While researchers are working hard towards finding a pinpointed answer as to what actually causes muscle soreness, there are ways you can prevent or at least alleviate soreness.
- Begin every workout by performing a warm-up prior to exercising. This elevates the heart rate, gets oxygenated blood to the muscles, and prepares the body for performance. A sufficient warm-up should have you sweating and breathing heavy.
- End each workout with a cool down. Do not skip out on these. Cool downs are essential for recovery.
- Schedule light exercise/deload/off days to keep the muscles moving, but not working hard enough to further muscle damage.
- Self myo-fascial release, or foam rolling, effectively reduces DOMs and fatique, and enhances muscle performance recovery (Pearcey).
- Supplements such as BCAAs help reduce muscle damage by suppressing the breakdown of muscle protein (Shimomura).
- Protein consumption after workout to aid in muscle repair
- If discomfort becomes troubling, small dose pain relievers such as Aleve may be taken. It is not recommended that this become habit, but may be useful at times. It should also be noted that anti-inflammatory drugs might inhibit the natural process of muscle repair (Roth).
It is nonrealistic to think that soreness can always be avoided, especially if beginning a new program. That being said, you should not be so sore after an exercise bout that you are unable to move or you are in severe pain. Whether you are beginning a new program, or are completely new to exercising, be sure ease into your training. Your body will need time to adapt to the workload.
References:
- Roth, Stephen M. “Why Does Lactic Acid Build up in Muscles”? And “Why Does It Cause Soreness”? Scientific American. Scientific American, a Division of Nature America, Inc., 23 Jan. 2006. Web. 18 Feb. 2016. <https://www.scientificamerican.com/article/why-does-lactic-acid-buil/>.
- Kedlaya, Divakara, MBBS. “Postexercise Muscle Soreness.” : Overview, Etiology, Histologic Findings. Medscape, 25 Jan. 2016. Web. 18 Feb. 2016. <https://emedicine.medscape.com/article/313267-overview>.
- Andersen, J. C. “Stretching Before and After Exercise: Effect on Muscle Soreness and Injury Risk.” Journal of Athletic Training. National Athletic Trainers Association, 2005. Web. 18 Feb. 2016. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1250267/>.
- Kenney, W. Larry, Jack Wilmore, and David Costill. “Physiology of Sport and Exercise 5E: Delayed-Onset Muscle Soreness.” Human-kinetics. N.p., 2015. Web. 18 Feb. 2016. <https://www.humankinetics.com/excerpts/excerpts/recent-research-provides-insight-into-muscle-soreness>.
- Shimomura, Yoshiharu. “Nutraceutical Effects of Branched-Chain Amino Acids on Skeletal Muscle.” The Journal of Nutrition. N.p., Feb. 2006. Web. 18 Feb. 2016. <https://jn.nutrition.org/content/136/2/529S.full>.
- Pearcey, Gregory E.P. “Foam Rolling for Delayed-Onset Muscle Soreness and Recovery of Dynamic Performance Measures.” National Athletic Trainers’ Association. N.p., Jan. 2015. Web. 18 Feb. 2016. <https://natajournals.org/doi/abs/10.4085/1062-6050-50.1.01>.
- Braun, William, Ph.D., and Gary Sforzo, Ph.D. “Delayed Onset Muscle Soreness.” (n.d.): n. pag. ACSM. 2011. Web. 18 Feb. 2016.








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