Recovery and Sleep Science

Adults pass through NREM stages and REM in cycles of roughly 90 minutes, four to six times a night.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

Slow-wave sleep dominates the early cycles; REM grows longer in the later cycles towards morning.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

The biggest growth hormone release of the day is tied to the first episode of slow-wave sleep.

Source: Van Cauter & Plat, J Pediatr 1996 · recall

Adenosine accumulates in the brain during wakefulness, increasing the homeostatic drive to sleep.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

Caffeine is an adenosine receptor antagonist, masking sleep pressure.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

Caffeine's half-life averages around 5 hours but ranges from about 2 to 10, so an afternoon dose can disturb sleep.

Source: Institute of Medicine, Caffeine for the Sustainment of Mental Task Performance 2001 · recall

Borbely's model pairs homeostatic sleep pressure (process S) with the circadian rhythm (process C).

Source: Borbely, Hum Neurobiol 1982 · recall

Melatonin rises in darkness in the evening and signals night to the circadian system; bright light suppresses it.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

Evening light, especially blue-rich light, suppresses melatonin and delays the circadian phase.

Source: Chang et al., PNAS 2015 · applied

A drop in core temperature accompanies sleep onset, which is why a cool bedroom helps and hard late training can delay sleep.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

The American Academy of Sleep Medicine and Sleep Research Society recommend at least 7 hours for adults.

Source: Watson et al., Sleep 2015 (AASM/SRS consensus) · recall

Aiming for 10 hours in bed cut 282-foot sprint times from 16.2 to 15.5 seconds (about 4%) and raised free-throw and three-point accuracy by about 9% each.

Source: Mah et al., Sleep 2011 · recall

Athletes sleeping less than 8 hours were 1.7 times more likely to be injured.

Source: Milewski et al., J Pediatr Orthop 2014 · recall

About two-thirds reported sleeping worse than normal before an important event, mainly from thoughts and nervousness.

Source: Juliff et al., J Sci Med Sport 2015 · recall

Short-term sleep loss after otherwise good sleep has small effects on most endurance performance; chronic restriction matters more.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · applied

Cognitive functions and mood are hit early and hard; single maximal efforts are more resistant.

Source: Fullagar et al., Sports Med 2015 · recall

Rated perceived exertion rises at a given workload after sleep loss, which shortens time to exhaustion.

Source: Fullagar et al., Sports Med 2015 · recall

Extra sleep in the preceding days can reduce the impact of later sleep loss on performance.

Source: Rupp et al., Sleep 2009 · recall

Short naps avoid deep slow-wave sleep and the sleep inertia that follows waking from it.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · recall

Studies using actigraphy often find athletes averaging under 7 hours, with long sleep latency and early training starts.

Source: Leeder et al., J Sports Sci 2012 · applied

Compared with active recovery, regular cold-water immersion attenuated long-term gains in muscle mass and strength.

Source: Roberts et al., J Physiol 2015 · recall

Reviews find cold-water immersion reduces soreness and helps perceived recovery in the short term.

Source: Bleakley et al., Cochrane Database Syst Rev 2012 · recall

Cooling reduces blood flow, inflammation and anabolic signalling after exercise, the same signals that drive adaptation.

Source: Roberts et al., J Physiol 2015 · recall

Use it when short-term recovery is the priority, such as stage races or a crowded race block, not when adaptation is.

Source: Ihsan et al., Sports Med 2016 · applied

Versey's review found most beneficial protocols used water around 10-15 C for about 10-15 minutes.

Source: Versey et al., Sports Med 2013 · recall

A Cochrane review found insufficient evidence that whole-body cryotherapy reduces soreness or improves recovery.

Source: Costello et al., Cochrane Database Syst Rev 2015 · recall

Participants believing in a "recovery" cream recovered strength about as well as those using cold water, showing a strong placebo effect.

Source: Broatch et al., Med Sci Sports Exerc 2014 · recall

Some studies show blunted mitochondrial or vascular signals, others no harm or even benefit, so the picture is unclear.

Source: Ihsan et al., Sports Med 2016 · recall

Regular cold-water immersion after resistance training can blunt the very adaptations the block is meant to produce.

Source: Roberts et al., J Physiol 2015 · applied

Immersion cannot be blinded, so expectation can shape soreness and performance outcomes.

Source: Broatch et al., Med Sci Sports Exerc 2014 · recall

The vitamins hampered cellular adaptations such as mitochondrial biogenesis markers, although performance changes were similar.

Source: Paulsen et al., J Physiol 2014 · recall

Reactive oxygen species help switch on adaptive pathways; blocking them with antioxidants can blunt training effects.

Source: Ristow et al., PNAS 2009 · recall

Exercise stress, including oxidative stress, triggers protective adaptations that leave the body more resilient.

Source: Radak et al., Ageing Res Rev 2008 · recall

The antioxidants abolished the exercise-induced improvement in insulin sensitivity.

Source: Ristow et al., PNAS 2009 · recall

Trappe showed ibuprofen and paracetamol reduced the post-exercise rise in muscle protein synthesis; later work suggests effects are dose-dependent.

Source: Trappe et al., Am J Physiol Endocrinol Metab 2002 · recall

NSAIDs reduce kidney blood flow; with dehydration and heat, ultramarathon users showed higher rates of acute kidney injury.

Source: Lipman et al., Ann Emerg Med 2017 · recall

Ibuprofen aggravated exercise-induced small-intestinal injury and gut barrier dysfunction.

Source: van Wijck et al., Med Sci Sports Exerc 2012 · recall

Runners taking cherry juice around a marathon recovered isometric strength faster and had lower inflammation markers.

Source: Howatson et al., Scand J Med Sci Sports 2010 · recall

Concern centres on high-dose supplements; a diet rich in fruit and vegetables has not been shown to impair adaptation.

Source: Merry & Ristow, J Physiol 2016 · applied

Routine pre-exercise NSAID use offers little benefit and adds gut, kidney and injury-masking risks.

Source: Lipman et al., Ann Emerg Med 2017 · applied

Time to exhaustion improved by about 32%, alongside an increase in plasma volume.

Source: Scoon et al., J Sci Med Sport 2007 · recall

Post-exercise hot-water immersion at 40 C lowered resting core temperature and improved running performance in the heat.

Source: Zurawlew et al., Scand J Med Sci Sports 2016 · recall

Heat shock proteins help fold and repair other proteins and increase with repeated heat stress.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Men using a sauna 4-7 times a week had lower rates of fatal cardiovascular events than once-weekly users.

Source: Laukkanen et al., JAMA Intern Med 2015 · recall

Sweat losses in a sauna can be large; entering dehydrated or combining with alcohol adds risk.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Studies of repeated local heating report preserved mitochondria and capillary growth, especially during immobilisation.

Source: Hafen et al., J Appl Physiol 2018 · recall

Post-exercise heating uses the raised core temperature from training, adding heat stress without extra training time.

Source: Zurawlew et al., Scand J Med Sci Sports 2016 · applied

Starting hot and partly dehydrated raises heart rate and perceived effort and impairs performance.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · applied

Heat and sweating stimulate aldosterone and albumin changes that expand plasma volume over repeated exposures.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Heat lowers blood pressure and loads the heart, so those with cardiovascular conditions should take medical advice.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Compression gave small to moderate improvements, most clearly in the recovery of strength, especially after 24 hours.

Source: Brown et al., Sports Med 2017 · recall

Among recovery techniques, massage showed the largest effect on delayed-onset muscle soreness and perceived fatigue.

Source: Dupuy et al., Front Physiol 2018 · recall

Wiltshire found massage impaired blood flow and lactate removal compared with active recovery.

Source: Wiltshire et al., Med Sci Sports Exerc 2010 · recall

A meta-analysis found small benefits for perceived soreness and sprint performance, trivial for others.

Source: Wiewelhove et al., Front Physiol 2019 · recall

Low-intensity activity keeps blood flowing and lactate being oxidised, clearing it faster than passive rest.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Blood lactate returns to baseline within an hour of rest, so it is not what limits next-day performance.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · applied

Sequential inflation of leg chambers is meant to move fluid; evidence for performance recovery is limited.

Source: Overmayer & Driller, Int J Sports Physiol Perform 2018 · recall

Expectation can improve how recovered athletes feel and even perform, as placebo studies show.

Source: Broatch et al., Med Sci Sports Exerc 2014 · applied

Recovery tools offer small, mostly perceptual benefits; sleep and energy and carbohydrate intake dominate recovery.

Source: Kellmann et al., Int J Sports Physiol Perform 2018 (recovery consensus) · recall

Sleep provides the largest recovery effect; gadgets cannot make up for chronic sleep shortage.

Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus) · applied

Muscles producing force while lengthening, as in downhill running, suffer the greatest damage.

Source: Proske & Morgan, J Physiol 2001 · recall

Running downhill increases braking forces absorbed by lengthening quadriceps.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · applied

Warren argued that strength loss is the most valid and reliable indirect measure; creatine kinase varies widely between people.

Source: Warren et al., Sports Med 1999 · recall

Creatine kinase responses differ greatly between "high" and "low" responders, so single values are hard to interpret.

Source: Baird et al., J Nutr Metab 2012 · recall

After one damaging bout, a similar bout days or weeks later causes much less damage and soreness.

Source: McHugh, Scand J Med Sci Sports 2003 · recall

McHugh described neural, mechanical and cellular adaptations that together reduce damage.

Source: McHugh, Scand J Med Sci Sports 2003 · recall

Muscle function and damage markers can take several days to a week or more to recover after a marathon.

Source: Clarkson & Hubal, Am J Phys Med Rehabil 2002 · recall

Cycling is mainly concentric, while running absorbs impact with lengthening contractions every stride.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · applied

Prior exposure to eccentric downhill loading reduces damage and soreness on race day.

Source: McHugh, Scand J Med Sci Sports 2003 · applied

Costill found glycogen resynthesis was impaired after eccentric damage, even with high carbohydrate intake.

Source: Costill et al., J Appl Physiol 1990 · recall

Muscle contraction translocates GLUT4 glucose transporters to the cell membrane independently of insulin.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Delaying intake reduced the rate of glycogen resynthesis compared with feeding immediately.

Source: Ivy et al., J Appl Physiol 1988 · recall

Glycogen depletion activates glycogen synthase, speeding storage.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Fructose is metabolised largely by the liver, so glucose-fructose mixes refill liver glycogen better than glucose alone.

Source: Gonzalez et al., Am J Physiol Endocrinol Metab 2017 · recall

Protein boosts glycogen resynthesis mainly when carbohydrate intake is suboptimal; with ample carbohydrate the effect disappears.

Source: Beelen et al., Int J Sport Nutr Exerc Metab 2010 · recall

With enough carbohydrate, muscle glycogen can be largely restored within about a day.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Gluconeogenesis creates glucose from non-carbohydrate sources such as lactate, glycerol and some amino acids.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

Lactate travels to the liver, is converted to glucose and returned to the blood.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

When the next session is soon, starting carbohydrate intake quickly maximises what is stored; with a day between, total intake matters more.

Source: Burke et al., J Sports Sci 2011 · applied

The liver releases glucose into the blood; its stores fall overnight and during long exercise.

Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.) · recall

About 13% of finishers reported illness in the week after, against about 2% of similar runners who did not race.

Source: Nieman et al., J Sports Med Phys Fitness 1990 · recall

The theory held that immune function is suppressed for 3-72 hours after strenuous exercise, raising infection risk.

Source: Pedersen & Ullum, Med Sci Sports Exerc 1994 · recall

They argued the drop reflects redistribution to tissues for surveillance, not suppression.

Source: Campbell & Turner, Front Immunol 2018 · recall

Exposure to many people, travel, sleep loss and psychological stress contribute strongly to illness around events.

Source: Campbell & Turner, Front Immunol 2018 · recall

Nieman proposed that moderate activity lowers infection risk below sedentary levels, while very heavy loads raise it.

Source: Nieman, Int J Sports Med 1994 · recall

Secretory IgA is the main antibody in mucosal secretions; low levels have been linked to more respiratory infections.

Source: Walsh et al., Exerc Immunol Rev 2011 · recall

Meta-analysis found vitamin D supplementation modestly reduced acute respiratory infection, mainly in deficient people.

Source: Martineau et al., BMJ 2017 · recall

Zinc acetate lozenges started within 24 hours of symptoms have been shown to shorten colds in some trials.

Source: Hemila, JRSM Open 2017 · recall

Hand hygiene reduces respiratory infection transmission and is recommended for athletes, especially when travelling.

Source: Walsh, Eur J Sport Sci 2018 · recall

Reducing exposure and practising hygiene is the most direct way to lower infection risk before an event.

Source: Walsh, Eur J Sport Sci 2018 · applied

Their review found subjective wellbeing measures responded more consistently to training load than common objective markers.

Source: Saw et al., Br J Sports Med 2016 · recall

Falls in jump height or related variables are used to monitor neuromuscular fatigue.

Source: Claudino et al., J Sci Med Sport 2017 · recall

Kentta and Hassmen proposed rating perceived recovery on a scale from 6 to 20, mirroring the Borg scale.

Source: Kentta & Hassmen, Sports Med 1998 · recall

Faster heart rate recovery reflects parasympathetic reactivation and can change with training status and fatigue.

Source: Daanen et al., Int J Sports Physiol Perform 2012 · recall

Monitoring data only mean something when a change exceeds the day-to-day variation of the measure.

Source: Hopkins, Sportscience 2004 · recall

One-off values vary; trends across days and combining measures with how the athlete feels give a truer picture.

Source: Saw et al., Br J Sports Med 2016 · applied

The Recovery-Stress Questionnaire for Athletes measures both stress and recovery-related activities and feelings.

Source: Kellmann & Kallus, Recovery-Stress Questionnaire for Athletes 2001 · recall

A drop in performance at a known effort is the most direct sign that recovery is incomplete.

Source: Meeusen et al., Med Sci Sports Exerc 2013 (overtraining consensus) · recall

Compliance and honest answering can fall, especially if athletes see no response to what they report.

Source: Saw et al., Br J Sports Med 2016 · applied

Converging signals from different measures are more convincing than any one alone.

Source: Saw et al., Br J Sports Med 2016 · applied