# Recovery and Sleep Science · Triathlon Level 7: Upper-Advanced

Triathlon · Level 7: Upper-Advanced · Insporta Book (https://book.insporta.app/triathlon/level-7/recovery-and-sleep-science/)

Recovery and Sleep Science in Triathlon (Level 7: Upper-Advanced) on Insporta: 100 sourced facts behind 10 tests. Covers: sleep architecture; and more.

The science behind recovery: sleep architecture and sleep loss, cold water and what it does to adaptation, anti-inflammatories and antioxidants, heat therapy, compression and massage, muscle damage and the repeated-bout effect, refuelling mechanisms, immunity, and how recovery is measured.

## Test 1: Sleep Architecture

- 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))
- 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))
- 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)
- 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))
- Caffeine is an adenosine receptor antagonist, masking sleep pressure. (Source: Walsh et al., Br J Sports Med 2021 (sleep and the athlete consensus))
- 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)
- Borbely's model pairs homeostatic sleep pressure (process S) with the circadian rhythm (process C). (Source: Borbely, Hum Neurobiol 1982)
- 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))
- Evening light, especially blue-rich light, suppresses melatonin and delays the circadian phase. (Source: Chang et al., PNAS 2015)
- 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))

## Test 2: Sleep Loss, Extension and Performance

- 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))
- 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)
- Athletes sleeping less than 8 hours were 1.7 times more likely to be injured. (Source: Milewski et al., J Pediatr Orthop 2014)
- 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)
- 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))
- Cognitive functions and mood are hit early and hard; single maximal efforts are more resistant. (Source: Fullagar et al., Sports Med 2015)
- Rated perceived exertion rises at a given workload after sleep loss, which shortens time to exhaustion. (Source: Fullagar et al., Sports Med 2015)
- Extra sleep in the preceding days can reduce the impact of later sleep loss on performance. (Source: Rupp et al., Sleep 2009)
- 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))
- 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)

## Test 3: Cold-Water Immersion and Adaptation

- Compared with active recovery, regular cold-water immersion attenuated long-term gains in muscle mass and strength. (Source: Roberts et al., J Physiol 2015)
- Reviews find cold-water immersion reduces soreness and helps perceived recovery in the short term. (Source: Bleakley et al., Cochrane Database Syst Rev 2012)
- Cooling reduces blood flow, inflammation and anabolic signalling after exercise, the same signals that drive adaptation. (Source: Roberts et al., J Physiol 2015)
- 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)
- 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)
- A Cochrane review found insufficient evidence that whole-body cryotherapy reduces soreness or improves recovery. (Source: Costello et al., Cochrane Database Syst Rev 2015)
- 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)
- 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)
- 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)
- Immersion cannot be blinded, so expectation can shape soreness and performance outcomes. (Source: Broatch et al., Med Sci Sports Exerc 2014)

## Test 4: Anti-Inflammatories and Antioxidants

- The vitamins hampered cellular adaptations such as mitochondrial biogenesis markers, although performance changes were similar. (Source: Paulsen et al., J Physiol 2014)
- Reactive oxygen species help switch on adaptive pathways; blocking them with antioxidants can blunt training effects. (Source: Ristow et al., PNAS 2009)
- Exercise stress, including oxidative stress, triggers protective adaptations that leave the body more resilient. (Source: Radak et al., Ageing Res Rev 2008)
- The antioxidants abolished the exercise-induced improvement in insulin sensitivity. (Source: Ristow et al., PNAS 2009)
- 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)
- 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)
- Ibuprofen aggravated exercise-induced small-intestinal injury and gut barrier dysfunction. (Source: van Wijck et al., Med Sci Sports Exerc 2012)
- 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)
- 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)
- Routine pre-exercise NSAID use offers little benefit and adds gut, kidney and injury-masking risks. (Source: Lipman et al., Ann Emerg Med 2017)

## Test 5: Heat Therapy and Sauna

- Time to exhaustion improved by about 32%, alongside an increase in plasma volume. (Source: Scoon et al., J Sci Med Sport 2007)
- 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)
- 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.))
- 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)
- 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.))
- Studies of repeated local heating report preserved mitochondria and capillary growth, especially during immobilisation. (Source: Hafen et al., J Appl Physiol 2018)
- 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)
- 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.))
- 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.))
- 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.))

## Test 6: Compression, Massage and Recovery Devices

- Compression gave small to moderate improvements, most clearly in the recovery of strength, especially after 24 hours. (Source: Brown et al., Sports Med 2017)
- Among recovery techniques, massage showed the largest effect on delayed-onset muscle soreness and perceived fatigue. (Source: Dupuy et al., Front Physiol 2018)
- Wiltshire found massage impaired blood flow and lactate removal compared with active recovery. (Source: Wiltshire et al., Med Sci Sports Exerc 2010)
- A meta-analysis found small benefits for perceived soreness and sprint performance, trivial for others. (Source: Wiewelhove et al., Front Physiol 2019)
- 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.))
- 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.))
- 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)
- Expectation can improve how recovered athletes feel and even perform, as placebo studies show. (Source: Broatch et al., Med Sci Sports Exerc 2014)
- 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))
- 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))

## Test 7: Muscle Damage and the Repeated-Bout Effect

- Muscles producing force while lengthening, as in downhill running, suffer the greatest damage. (Source: Proske & Morgan, J Physiol 2001)
- Running downhill increases braking forces absorbed by lengthening quadriceps. (Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.))
- 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)
- 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)
- 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)
- McHugh described neural, mechanical and cellular adaptations that together reduce damage. (Source: McHugh, Scand J Med Sci Sports 2003)
- 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)
- Cycling is mainly concentric, while running absorbs impact with lengthening contractions every stride. (Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.))
- Prior exposure to eccentric downhill loading reduces damage and soreness on race day. (Source: McHugh, Scand J Med Sci Sports 2003)
- Costill found glycogen resynthesis was impaired after eccentric damage, even with high carbohydrate intake. (Source: Costill et al., J Appl Physiol 1990)

## Test 8: Refuelling Mechanisms

- Muscle contraction translocates GLUT4 glucose transporters to the cell membrane independently of insulin. (Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.))
- Delaying intake reduced the rate of glycogen resynthesis compared with feeding immediately. (Source: Ivy et al., J Appl Physiol 1988)
- Glycogen depletion activates glycogen synthase, speeding storage. (Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.))
- 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)
- 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)
- With enough carbohydrate, muscle glycogen can be largely restored within about a day. (Source: Kenney, Wilmore & Costill, Physiology of Sport and Exercise (8th ed.))
- 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.))
- 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.))
- 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)
- 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.))

## Test 9: Immunity and Illness Risk

- 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)
- 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)
- They argued the drop reflects redistribution to tissues for surveillance, not suppression. (Source: Campbell & Turner, Front Immunol 2018)
- Exposure to many people, travel, sleep loss and psychological stress contribute strongly to illness around events. (Source: Campbell & Turner, Front Immunol 2018)
- Nieman proposed that moderate activity lowers infection risk below sedentary levels, while very heavy loads raise it. (Source: Nieman, Int J Sports Med 1994)
- 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)
- Meta-analysis found vitamin D supplementation modestly reduced acute respiratory infection, mainly in deficient people. (Source: Martineau et al., BMJ 2017)
- Zinc acetate lozenges started within 24 hours of symptoms have been shown to shorten colds in some trials. (Source: Hemila, JRSM Open 2017)
- Hand hygiene reduces respiratory infection transmission and is recommended for athletes, especially when travelling. (Source: Walsh, Eur J Sport Sci 2018)
- Reducing exposure and practising hygiene is the most direct way to lower infection risk before an event. (Source: Walsh, Eur J Sport Sci 2018)

## Test 10: Measuring Recovery and Readiness

- 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)
- Falls in jump height or related variables are used to monitor neuromuscular fatigue. (Source: Claudino et al., J Sci Med Sport 2017)
- Kentta and Hassmen proposed rating perceived recovery on a scale from 6 to 20, mirroring the Borg scale. (Source: Kentta & Hassmen, Sports Med 1998)
- 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)
- Monitoring data only mean something when a change exceeds the day-to-day variation of the measure. (Source: Hopkins, Sportscience 2004)
- 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)
- The Recovery-Stress Questionnaire for Athletes measures both stress and recovery-related activities and feelings. (Source: Kellmann & Kallus, Recovery-Stress Questionnaire for Athletes 2001)
- 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))
- 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)
- Converging signals from different measures are more convincing than any one alone. (Source: Saw et al., Br J Sports Med 2016)

Sources: Peer-reviewed exercise physiology and sports medicine literature, with standard textbooks for settled facts

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