Breaking It Down: The Fascinating Science of Recovery
“Anyone can work hard. The best have the discipline to recover.” – Lauren Fleshman
Recovery is a majorly underrated component of training, one that athletes commonly neglect entirely. However, without the discipline to rest on easy days, eat properly, and get adequate sleep, hard training does more damage than good. The science of recovery is fascinating, and a little bit of understanding goes a long way in taking recovery seriously.
What Happens During Recovery?
During strenuous exercise such as resistance training or aerobic threshold intervals, muscle tissue develops micro-tears in response to stress. Immediately following exercise, the recovery process begins via acute inflammation.
While many people assume that inflammation is bad, in reality, short-term inflammation is actually a good thing. When the immune system1 detects damage to muscles and tissues due to exercise, it sends pro-inflammatory cells called neutrophils and macrophages to the affected areas. Neutrophils are a type of white blood cell formed in bone marrow and stem cells and are the “first responders” to injury sites via blood vessels and tissues. Macrophages are another type of white blood cell that consume cellular debris not implicated in healthy processes. The combination of neutrophils and macrophages helps to stimulate regeneration of the damaged area.
Inflammation © Dreamstime
The cascading of immune cells to the area also results in increased fluid flow, which causes the characteristic swelling and soreness following difficult exercise. To help speed up repairs to the muscular system, a growth hormone called insulin-like growth factor-12 (IGF-1) is secreted. The binding of this protein to special receptors in damaged areas causes the signaling of cell growth while prohibiting cell death. The IGF-1 hormone also signals satellite cells to initiate the growth of new muscle fibers.
These satellite cells appear on the borders of the damaged muscle fibers and have the proliferative properties of stem cells. They work to differentiate the damaged fibers into new muscle tissue. The only way to stimulate this process is via cellular damage, so this degeneration-regeneration phase is crucial for both recovery and the building of strength. Altogether, the acute inflammation phase can last up to 72 hours.
Besides muscle repair, glycogen stores must be replenished following exhaustive exercise. Glycogen is the fuel that is stored in muscles for the conversion of energy. Carbohydrates are the main source of glycogen, and the liver mediates the conversion of glycogen into glucose for quick energy consumption during exercise. Besides fueling muscles during exercise, glycogen is also important for recovery, and inadequate glycogen stores can hinder the body’s muscle restoration.
In order to restore muscular glycogen, carbohydrates must be consumed. Numerous studies have found that consuming 550 – 625 grams of carbohydrates per day will restore muscular glycogen to pre-exercise levels within 24 hours. Without glycogen replenishment, further damage will be sustained to the body as muscle and fat are recruited for energy during subsequent exercise sessions.
Which Habits are Beneficial for Recovery?
Recovery © Dreamstime
1. Post-Workout Snack
Within 30 minutes of moderate-to-vigorous exercise, athletes should consume a 200 – 300 calorie snack that has a carbohydrate to protein ratio of 4:1 or 3:13. This ratio is best for stimulating muscle growth by providing protein for muscle synthesis and carbohydrates for glycogen replenishment.
Other studies have shown that caffeine post-exercise can stimulate muscle repair while reloading glycogen stores. However, in order for an athlete to receive the full benefit, mega doses of caffeine must be consumed, the equivalent of 6 – 7 cups of coffee worth.
Caffeine © Dreamstime
When muscle soreness persists for longer than 72 hours, it is necessary to take a day off from exercise. While active recovery is often touted as being beneficial, nothing beats a full day of rest and relaxation. When your body is being stubborn in the repair process, limit further damage and allow for full rest.
4. Easy Days
A common mistake that runners make is to run hard every day. Since the full acute inflammation process can take up to 72 hours, it is important to allow yourself easy days in between hard training sessions. By continually breaking down muscle tissue you risk chronic inflammation, which hinders the recovery process by causing chronic degeneration of healthy muscle tissue.
5. Warm Up
A Norwegian study4 found that a prolonged warm up before exercise was more beneficial for recovery than even a cool down. An adequate warm up consists of easy running, mobility drills, and strides; all of which gently prime the muscular and skeletal system for the work ahead, and mitigate the amount of damage sustained during the workout.
Compression © Dreamstime
Although there are conflicting reports whether compression is beneficial for speed, we do know that compression gear can speed up recovery5. Why? Compression socks and sleeves cause blood vessel dilation, allowing more blood – and netrophils/macrophages – to flow to lower limbs.
Muscular damage causes a cascade of reactive oxygen species; the scientific term for free radicals. When free radical proliferation is out of control, cancer and other disease states can occur. One way reactive oxygen species can be mitigated is through the consumption of antioxidants such as Vitamin C and Vitamin E. However, care should be taken not to overload on antioxidants year-round. Other studies have shown that reactive oxygen species have beneficial effects, such as the triggering of neurogenesis6 in the brain.
Which Habits are Not Beneficial for Recovery?
1. Cool Down
A long held belief is that a post-run cool down is necessary for recovery. New research4 has suggested that a cool down is not necessary for the flushing of metabolic waste products from the muscles and blood; instead, the cool down is beneficial for increasing mileage and benefits a runner’s efficiency, as it causes the athlete to run on tired legs. Still, many athletes swear by cool downs to help their legs feel better post-workout. While you can (and should) continue this habit, know that it likely isn’t going to prevent soreness the following day.
2. Ice Bath
Ice baths are continually lauded as the best – or worst – thing for recovery. From a scientific perspective, ice baths may be hindering your recovery. The acute inflammation process relies on the transport of neutrophils and macrophages through blood vessels to the damaged area. However, ice baths constrict blood vessels, which may make transport to these areas more difficult, especially for the large macrophiles. While an ice bath will reduce inflammation in the short term, it may do so at the risk of recovery.
Pain © Dreamstime
3. Anti-Inflammatory Drugs
Do you finish a long run and head straight to the medicine cabinet for anti-inflammatory pain relievers? If so, you may be seriously hindering your natural recovery process. Anti-inflammatory drugs inhibit the body’s natural immune system response in order to circumvent the pain associated with inflammation. While this is good for you in the short term, it robs the body of regeneration7.
How to Hack Recovery in Special Circumstances
There are circumstances where hindering inflammation may be beneficial. For instance, if you are racing two days back to back, inhibiting the inflammatory response by taking an ice bath or anti-inflammatory drugs will delay the soreness until after your second race. While this “hack” is not recommended for everyday training, this approach may help you perform your best in certain scenarios.
1. Woods J, Vieira V, Keylock K. Exercise, inflammation, and innate immunity. Neurol Clin. 2006;24(3):585–599. Link
2. Trejo J. L., Carro E. & Torres-Alemán I. Circulating Insulin-Like Growth Factor I Mediates Exercise-Induced Increases in the Number of New Neurons in the Adult Hippocampus. The Journal of Neuroscience 21, 1628–1634 (2001). Link
3. Howarth K. R., Moreau N. A., Phillips S. M., Gibala M. J. (2009). Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans. J. Appl. Physiol. 106, 1394–1402. 10.1152/japplphysiol.90333.2008 Link
4. Olsen O, Sjøhaug M, van Beekvelt M, Mork PJ. 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. 2012;35:59-68. doi:10.2478/v10078-012-0079-4. Link
5. Ali A, Caine MP, Snow BG. Graduated compression stockings: physiological and perceptual responses during and after exercise. J Sports Sci. 2007;25:413–419. Link
6. Zsolt Radaka, Orsolya Martona. The complex role of physical exercise and reactive oxygen species on brain. Journal of Sport and Health Science. Vol 2; 2, June 2013, 87–93 Link
7. Machida M., Takemasa T. (2010) Ibuprofen administration during endurance training cancels running-distance-dependent adaptations of skeletal muscle in mice. J. Physiol. Pharmacol. 61, 559–563 Link