Response and adaptation to training and exercise

When getting back to the grind after a good break from a long season, or when at the beginning of a new training or exercise routine, the body usually feels sore. For seasoned veterans, early season training feels very challenging; lets face it, getting back into shape can feel like a daunting task. For those trying a new training regime or a new sport, the new movements will leave you a little sore. This soreness is called delayed onset muscle soreness, DOMS. However as you continue to exercise, the body will respond and begin to adapt to the different stimulus, allowing you to increase intensity and be more efficient.

As your body is introduced to a new stimulus or reintroduced to a stimulus, damage occurs to muscle fibers. These small tears may be what causes the decrease in muscle function, tenderness and swelling in certain areas felt 8 to 72 hours after exercise. There is no need to worry. As the muscle fibers begin to repair themselves, you will be able to handle the workload much better. Your body will respond and begin to adapt to the training or activity.

The ability of the body to respond to a new stimulus and adapt to these demands is what allows us to exercise and improve fitness. There are two kinds of responses to physical exercise or training:

1. Acute response is an immediate response to exercise, lasting for the duration of the exercise or training session. This could include changes in the cardiovascular, respiratory and muscular systems depending on the intensity and duration. 
2. Chronic adaptation refers to long term changes, over 6 or more weeks, that occur during exercise and can include improved cardiovascular adaptation, respiratory adaptation, muscle tissue adaptation to aerobic training, cardiac hypertrophy, muscular hypertrophy and increased muscle stores.

Some people quit the activity due to the pain and soreness that occurs hours after exercising. The feeling of soreness is only temporary and, after a few days of recovery before going back to the activity, the muscles will be more resilient and less damage will occur. As you continue to exercise, the muscles will adapt to the stress; this is known as repeated bout effect. Essentially for the soreness to go away and for you to get any long-term benefits from your exercise, the exercise has to be repeated over and over again. If you decided to play basketball once every three weeks as opposed to once every three days, every time you play you are most likely to feel sore. Thus playing every three days allows you to adapt and improve fitness steadily.

Every acute response and chronic adaptation reaction depends on the stimulus you put your body through. Your body will respond differently to activities such as running and cycling (endurance training) than it will from lifting weights or resistance training. Soreness after the first day is usually a sign of DOMS and with good recovery you should be able to do the same movements in a few days with less pain. In the long term you should be able to increase intensity and duration as the body responds and adapts.


References from the SIRC Collection:

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4. Hawley J. Adaptations Of Skeletal Muscle To Prolonged, Intense Endurance Training. Clinical & Experimental Pharmacology & Physiology [serial online]. March 2002;29(3):218-222.

5. Olsen O, Sjøhaug M, van Beekvelt M, Mork P. The Effect of Warm-Up and Cool-Down Exercise on Delayed Onset Muscle Soreness in the Quadriceps Muscle: a Randomized Controlled Trial. Journal Of Human Kinetics. December 2012;35:59-68.

6. Starbuck C, Eston R. Exercise-induced muscle damage and the repeated bout effect: evidence for cross transfer. European Journal Of Applied Physiology. March 2012;112(3):1005-1013.

7. Steele J, Fisher J, McGuff D, Bruce-Low S, Smith D. Resistance Training to Momentary Muscular Failure Improves Cardiovascular Fitness in Humans: A Review of Acute Physiological Responses and Chronic Physiological Adaptations. Journal Of Exercise Physiology Online. June 2012;15(3):53-80.

8. Walker S, Ahtiainen J, Häkkinen K. Acute neuromuscular and hormonal responses during contrast loading: Effect of 11 weeks of contrast training. Scandinavian Journal Of Medicine & Science In Sports. April 2010;20(2):226-234.