The Science Of Performance And Recovery For Athletes
The more you train to achieve peak performance, the more you need to maximize your recovery time. Over the last few decades, exercise science has advanced, as has our understanding of how to best recover in order to reach our peak fitness level. Gone are the days when recovery was synonymous with a long nap or a day off. Athletes are trying many techniques to speed up the recovery process.
After overloading muscle tissue with eccentric exercise, symptoms of exercise-induced muscle damage are expected. Symptoms may include reduced muscle strength, decreased range of motion, swelling, increased protein in the blood, and delayed onset muscle soreness.1 These temporary symptoms improve during the recovery period. Stressing the muscles before they are fully recovered might cause muscular injury and decreased performance. When the difference between winning and losing is measured in milliseconds, any recovery method that helps expedite healing is helpful.
Recovery is necessary to help athletes bounce back from training and solidify their fitness gains. Recovery is essential to reduce physical and psychological stress, avoid joint overload, and mitigate fatigue. The recovery process may look different for each person.
Table of Contents
How Does Recovery Improve Performance?
Recovery is an essential part of the principle of training, which refers to the systematic and progressive process of improving physical performance through the use of specific training methods. The training principle is based on the idea that the body adapts to the demands placed on it and that by progressively increasing the intensity and volume of training (overloading), an athlete can improve their physical performance. This is different from over-training, which impairs rather than improves performance.2
Recovery is the process of repairing and rebuilding the body following physical exertion. It is an essential part of any training program, as it helps the body adapt to exercise demands and improve performance.
There are several ways in which recovery can improve performance, including:2,3
- Repairing muscle tissue: During recovery, the body repairs and rebuilds damaged muscle tissue, which can help to improve muscle strength and endurance.
- Reducing muscle soreness: Recovery can help to reduce muscle soreness and fatigue. It allows time to flush lactic acid and other metabolic byproducts from muscle tissue.
- Reducing central fatigue: Adequate sleep is an important part of the recovery process, as it allows the body to rest and repair itself. Poor sleep can negatively affect performance.
- Reducing the risk of injury: Proper recovery can help reduce the risk of injury by allowing the body to repair itself and help prevent muscle imbalances and overuse injuries.
- Enhancing mental well-being: Recovery can also help to improve mental well-being by reducing stress and fatigue, which can help to improve focus and motivation.
What Are The Recovery Methods?
Several strategies can facilitate recovery in sports, including:
Consuming a balanced diet that includes sufficient amounts of carbohydrates, protein, and healthy fats can help support recovery. Choosing your nutrition wisely will restore muscle and liver glycogen stores, replace fluids and electrolytes lost in sweat, promote faster muscle repair, and support the immune system.
When planning your nutrition for the day, choose a nutrient-dense, whole-food diet high in micronutrients. Also, consider the following:
- Macronutrient ratios (fats, carbohydrates, and proteins)
- Meal and snack timing
- Vitamins and minerals
According to the Dietary Guidelines for Americans 2020-2025, the optimal percentages of macronutrients for adults are:
- Carbohydrates: 45-65% of daily calories
- Protein: 10- 35% of daily calories
- Fat: 20-35% of daily calories
An endurance athlete would increase their carbohydrate percentage, and a strength athlete may increase their percentage of proteins. According to International Sports Sciences Association (ISSA):
- Endurance athletes should eat 8 to 10 grams of carbohydrates per kilogram (kg) of body weight per day. On the higher range, if the event lasts 4 hours or more.
- Power athletes should consume around 4 to 5 grams of carbohydrates per kilogram of body weight per day.
For more detailed information on sports nutrition, read the International Society of Sports Exercise and Nutrition Research and Recommendations.
Other recommendations from the Dietary Guidelines for Americans and ISSA include:4
- Limit added sugars, saturated fats, sodium, and alcoholic beverages
- Fill half your plate with fruits and vegetables
- Make half your grains whole grains
- Choose healthy sources of protein
- Move to low-fat or fat-free milk or yogurt
- Choose complex carbohydrates or naturally occurring sugars instead of processed or refined sugars
- Consume around 0.8 grams/kg/day of protein
Sleep is critical to physical, mental, and emotional recovery. Aim for 8 to 10 hours of quality sleep during periods of heavier training. Otherwise, aim for 7 to 9 hours of quality sleep each night.
About one-third of U.S. adults are sleep deprived. Sleep deprivation can increase the risk of obesity, diabetes, cardiovascular disease, high blood pressure, and depression. In one study, athletes who slept less than 8 hours per night for two weeks were 1.7 times more likely to have an injury than athletes who got enough sleep.5 In another study, runners who slept less were slower and felt like they were working harder when compared to runners who got at least 7 hours of sleep.6
Staying hydrated is essential for recovery, as it helps to replace fluids and electrolytes lost during exercise. Endurance athletes are at increased risk of dehydration, but adequate hydration is important for everyone. Water is the most abundant molecule in the body, representing up to 70% of body mass.7
When you don’t exercise, your kidneys adjust urine production to match fluid intake. However, when you exercise, especially in warm, humid environments, sweat production to release the heat generated during metabolism can reach 3-4 liters per hour in some well-trained people. Many athletes do not replace fluids at the same rate as they are lost, leading to dehydration by the end of the event. Experts believe that losing more than 2% of body weight due to dehydration affects performance.8
Changes in body physiology due to dehydration:8
- Reduced plasma volume
- Reduced cardiac output and stroke volume
- Reduced blood flow to skeletal muscle
- Increased body temperature
- Increased glycogen use
- Increased perceived exertion
Massage And Percussion
Massage and other soft tissue work, such as foam rolling or stretching, can help to improve circulation and reduce muscle soreness. Percussive devices combine compression and vibration into one device. Research suggests that percussive therapy improves muscle stiffness and is superior to foam rolling and mechanical vibration. Targeted frequency appears to be between 12 Hz and 120 Hz, depth of 0.5 mm to 5 mm, and a treatment duration of 15 seconds up to 30 minutes to achieve the desired clinical goals.9,10
Cold Water Immersion (Cryotherapy)
Cold therapy decreases skin and muscle temperature, decreasing metabolism and blood flow to an injury, which reduces swelling and inflammation from tissue damage. Cold therapy also relieves pain, slows nerve impulses transmitting pain signals to the brain, and may reduce delayed onset muscle soreness.
Cold immersion is a technique made popular through the work of Wim Hof, a Dutch physiologist, and explorer. Wim Hof uses a combination of breathwork and intermittent cold exposure to adjust internal physiology. Cold immersion constricts blood vessels. When blood vessels constrict and then dilate, a pumping action occurs in the tissue. In one study, participants who performed breathing exercises, meditated, and were immersed in ice-cold water had better immune function than the control group.11
Further research is needed to determine the optimal cold water immersion technique and its safety.12 A 2017 review suggested that cold water immersion improves neuromuscular performance for 24 hours, but the benefits do not extend past this period. They recommended that cold water immersion include two exposures of 10°C for 5 minutes each, and athletes should sit in ambient temperature for 2 minutes between exposures.13 Multiple other studies support this finding and suggest that ideal temperatures are between 11°C and 15°C for 11 to 15 minutes to reduce DOMS and enhance recovery.14
Hyperbaric Oxygen Therapy
Hyperbaric oxygen chambers are used to help with tissue healing. Initially, hyperbaric oxygen therapy (HBOT) was used to treat decompression sickness when scuba divers ascended too quickly. HBOT chambers increase atmospheric pressure to increase the volume of oxygen absorbed by tissues. The pressures used in HBOT are typically 2–3 times atmospheric pressure. HBOT uses 100% oxygen at increased pressures to deliver oxygen directly to body tissues instead of relying on the lungs and circulatory system to deliver it.15
HBOT is used to improve immune function and reduce inflammation and swelling. Increased oxygen causes blood vessels to constrict, which reduces swelling and inflammation. Over longer treatment periods, HBOT increases neovascularization and neo-angiogenesis (new blood vessels and increased blood flow). It is often used to treat wounds that are not healing well.15
Potential side effects from HBOT include barotrauma to the ears and sinuses from increased pressure and oxygen toxicity. Barotrauma can also occur in the lungs or in unfilled dental cavities. Oxygen toxicity is due to breathing increased concentrations of oxygen at increased pressures. In oxygen toxicity, an excessive number of free radicals are generated, which can cause nerve damage.15
More research is needed to determine whether HBOT treats musculoskeletal injuries or DOMS effectively. Clinicians should monitor athletes post-treatment for signs of central nervous system or lung toxicity and barotrauma.9
Neuromuscular Electrical Stimulation (NMES)
Neuromuscular electrical stimulation devices are composed of a power source, a stimulator, and electrodes. E-stim usually uses a pulsed waveform that can be adjusted for both amplitude and duration. The electrodes are placed on the skin to activate muscle fibers to generate a contraction. NMES units are also used to treat muscle spasms.9
Whole-body electrical stimulation can cause rhabdomyolysis, a serious condition due to the breakdown of muscle tissue. Germany and Israel are the only two countries that have instituted guidelines on the use of whole-body stimulation, including recommending use only by trained individuals, with adequate hydration before and after application and monitoring for rhabdomyolysis.16
The clinical application of neuromuscular electrical stimulation lacks consistent evidence to recommend it.9
Using equipment such as compression garments or recovery boots can help to improve circulation, reduce swelling, enhance metabolic waste removal, and reduce muscle soreness. A review of 40 studies suggested that:17
- There is no evidence that using compression garments is harmful.
- There is no evidence that compression garments reduce blood lactate levels, change venous blood flow, regulate skin or body temperature, improve performance or reduce the time to fatigue.
- Athletes perceive that compression garments reduce muscle damage and increase performance in endurance events.
- Compression garments reduce the risk of overuse and overload injuries.
The research supporting these recovery methods is inconclusive and probably varies by person and sport.
What Are The Three Principles Of Recovery?
Several principles of recovery are important to consider when developing a recovery plan:
- Individualization: Recovery strategies should be tailored to the specific needs and goals of the individual, as different people may respond differently to different recovery methods.
- Multi-modal approach: A multi-modal approach to recovery, which combines a variety of different strategies, may be more effective than relying on a single method.
- Progressive overload: Recovery strategies should be progressively increased in intensity and duration as the individual’s fitness level improves in order to continue making progress.
Other important principles of recovery include the importance of proper nutrition, adequate sleep, and the use of techniques such as massage and foam rolling to improve circulation and reduce muscle soreness. Finding a recovery routine that works best for an individual athlete is important, as different strategies may work better for different people. It is also important to listen to the body and allow for adequate rest and recovery time to optimize performance.
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- Hill J, Howatson G, van Someren K, Leeder J, Pedlar C. Compression garments and recovery from exercise-induced muscle damage: a meta-analysis. Br J Sports Med. Sep 2014;48(18):1340-6. doi:10.1136/bjsports-2013-092456
- Bishop PA, Jones E, Woods AK. Recovery from training: a brief review: brief review. J Strength Cond Res. May 2008;22(3):1015-24. doi:10.1519/JSC.0b013e31816eb518
- Chennaoui M, Vanneau T, Trignol A, et al. How does sleep help recovery from exercise-induced muscle injuries? J Sci Med Sport. Oct 2021;24(10):982-987. doi:10.1016/j.jsams.2021.05.007
- Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition. 2018/08/01 2018;15(1):38. doi:10.1186/s12970-018-0242-y
- Milewski MD, Skaggs DL, Bishop GA, et al. Chronic lack of sleep is associated with increased sports injuries in adolescent athletes. J Pediatr Orthop. Mar 2014;34(2):129-33. doi:10.1097/bpo.0000000000000151
- Huang K, Ihm J. Sleep and Injury Risk. Curr Sports Med Rep. Jun 1 2021;20(6):286-290. doi:10.1249/jsr.0000000000000849
- James LJ, Mears SA. Does dehydration really impair endurance performance? Recent methodological advances helping to clarify an old question. DGatorade Sports Science Institute. 2021;
- Cullen ML, Casazza GA, Davis BA. Passive Recovery Strategies after Exercise: A Narrative Literature Review of the Current Evidence. Curr Sports Med Rep. Jul 1 2021;20(7):351-358. doi:10.1249/jsr.0000000000000859
- Lu X, Wang Y, Lu J, et al. Does vibration benefit delayed-onset muscle soreness?: a meta-analysis and systematic review. J Int Med Res. Jan 2019;47(1):3-18. doi:10.1177/0300060518814999
- Kox M, van Eijk LT, Zwaag J, et al. Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans. Proc Natl Acad Sci U S A. May 20 2014;111(20):7379-84. doi:10.1073/pnas.1322174111
- Bleakley C, McDonough S, Gardner E, Baxter GD, Hopkins JT, Davison GW. Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise. Cochrane Database of Systematic Reviews. 2012;doi:10.1002/14651858.cd008262.pub2
- Higgins TR, Greene DA, Baker MK. Effects of Cold Water Immersion and Contrast Water Therapy for Recovery From Team Sport: A Systematic Review and Meta-analysis. J Strength Cond Res. May 2017;31(5):1443-1460. doi:10.1519/jsc.0000000000001559
- Machado AF, Ferreira PH, Micheletti JK, et al. Can Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-Analysis. Sports Med. Apr 2016;46(4):503-14. doi:10.1007/s40279-015-0431-7
- Moghadam N, Hieda M, Ramey L, Levine BD, Guilliod R. Hyperbaric Oxygen Therapy in Sports Musculoskeletal Injuries. Medicine & Science in Sports & Exercise. 2020;52(6)
- Stöllberger C, Finsterer J. Side effects of and contraindications for whole-body electro-myo-stimulation: a viewpoint. BMJ Open Sport Exerc Med. 2019;5(1):e000619. doi:10.1136/bmjsem-2019-000619
- Pérez-Soriano P, García-Roig Á, Sanchis-Sanchis R, Aparicio I. Influence of compression sportswear on recovery and performance: A systematic review. Journal of Industrial Textiles. 2019;48(9):1505-1524. doi:10.1177/1528083718764912