Recovery Strategies
Clyn Howatson and Tom Clifford
Highlights
- • Ensure the basics of hydration, nutrition and sleep are adequately catered for - no recovery intervention can hope to succeed unless these pillars are adequately met.
- • Determine if a strategy is necessary or whether adequate recovery can be attained without intervention.
- • Understand the training and competition stressors causing reductions in performance and the delayed recovery before applying the intervention - this will help you choose the right intervention.
- • Contemplate the relative importance of short-term recovery and long-term adaptation; consider how the idea of hormesis could be applied.
- • The importance of athlete belief in the intervention should not be underestimated.
Introduction
The concept of recovery has been an established ideology' of medicine that dates to Hippocrates (c. 460 BC). This idea is based on the premise that the maintenance of physiological balance through rest was central to healing. As years have advanced, the pursuit of improved athletic performance has led to athletes engaging in higher training volume and intensity, leading to the growing interest in exercise recovery strategies. This is particularly important when demanding training and competition schedules make the appropriate balance between physiological stress, recovery and subsequent adaptation difficult to optimise. A successful recovery regimen could lead to: (1) improved physiological adaptation; (2) reduced training- or competition-induced stress; (3) improve recovery times to allow for additional training stimulus; and (4) optimised recovery in periods of competition congestion.
Runners can adopt a huge range of strategies to help improve recovery, such as cryotherapy, compression garments and nutrition. Interestingly, there are many interventions that lack a solid evidence-base and their use is largely stooped in anecdote and hearsay. Importantly, many interventions are only likely to yield modest, but potentially meaningful changes in recovery However, these can only be realised if the fundamental principles of recovery are well executed; namely, adequate hydration, fuel restoration (with adequate carbohydrate, protein and fat) and good quality and quantity of sleep. This chapter aims to provide a combination of evidence for the fundamentals of exercise recovery, and to further explore some traditional and more contemporary strategies that might be of value to runners.
Principles and Approach to Recovery
Observations of amateur and professional athletic environments show an extensive use of recovery strategies but without a clear need or rationale. For example, it is critical to understand whether insufficient recovery is the cause of a reduction in the capacity to train or compete. Very often, with sufficient time, the body will recover without the need for additional interventions above and beyond the fundamentals of hydration, adequate nutrition and sleep. By having a good understanding of the physiological stress that is induced by training and competition, it is possible to discern what interventions might be of use. Distance running is characterised by a high metabolic demand that is coupled with a high degree of mechanical loading from the constant eccentric loaded contractions (where the muscle lengthens under tension) from repetitive ground contacts. When coupled, these challenges can produce muscle damage and inflammation and can increase the production of reactive oxygen and nitrogen species that cause oxidative stress. In the runner, this can manifest itself as reduced muscle function, greater muscle stiffness that leads to a loss of flexibility, and muscle soreness. If athletes train or compete whilst experiencing these symptoms, it is highly likely their performance will be below par. In addition to competing in a less-than-optimal state, there is an increased potential risk for injury (Howatson and Van Someren, 2008) because of the reduction in joint position sense and reaction time. In circumstances such as these, inadequate recovery is the underlying issue, and therefore identification of a recovery strategy to accelerate and restore function might be necessary. In a conceptual model of exercise recover)' (Figure 17.1), the restoration of function will occur over time, but the application of a recovery strategy has the potential to accelerate the return of function to the basal state sooner. This is particularly important during intensified training, and competition schedules where performance at the highest level is required frequently within short time periods.
Getting the Basics Right Re-Hydration
Most athletes will finish exercise with some degree of fluid deficit, also known as hypohydration (Evans et al., 2017). If hypohydration exceeds 2—3% loss in body mass, aerobic capacity, cognitive function and motor learning can be impaired (Funnell et al., 2019; James, Funnell, et al., 2019a) Thus, if the fluid deficit is not restored following exercise, subsequent performance could be compromised (Evans et al., 2017).
For optimal rehydration, it is currently recommended that 125-150% of fluid lost during exercise (estimated via body mass losses) is consumed in the subsequent hours (Evans et al., 2017). As an example, a 60 kg athlete, who weighs 1.5 kg less following a 90-minute run, should consume 1.75-2.00 litres of fluid in the hours following. This volume should not only restore hydration status but also cover additional losses from sweating and urination during the recovery period (Thomas et al., 2016). However, it is not always practical to weigh yourself
FIGURE 17.1 Conceptual timeline of the recovery process. The dashed black line indicates the timeline of unassisted recovery following training, where in the fullness of time, function is restored to the basal state. If a positive adaptive response is achieved, the basal state will be exceeded, and the target adaptive response can be achieved. If a further stimulus is not introduced to the system, the function will return to the basal state. The dashed grey line illustrates the conceptual introduction of a successful recovery strategy where the return of function is accelerated with no loss in any adaptive response
before and after training or competition to determine your fluid needs. One way to overcome this is to work out your sweat rate (e.g. litres lost per hour) for a given intensity, duration and environment, and then use these data to estimate your body mass losses in future events/ sessions in similar conditions (Evans et al., 2017). This is probably necessary only if training or competition is <8 hours apart, if you have a high sweat rate (>1.2 litres per hour) and if the preceding exercise was >2 hours. Where possible, fluid should be consumed with electrolytes such as sodium or alongside sodium-containing foods, as this promotes fluid absorption, retention and hence ensures faster re-hydration (Thomas et al., 2016).
Nutrition for Recovery From Endurance Exercise
Carbohydrates
Restoration of muscle and liver glycogen stores is of principal importance to the recovery process. This can be achieved by consuming carbohydrate-rich foods such as pasta, bread, rice and cereals. The volume and timing of carbohydrate intake is largely dictated by the duration and intensity of the completed exercise.
With regards to timing, when recover)' between moderate to hard training sessions is limited to <8 hours, carbohydrates should be consumed immediately upon the cessation of exercise (Ivy et al., 1988; Moore, 2015). This is to take advantage of the muscle contraction- induced increase in muscle and liver glycogen enzymes that are active immediately in the hours following exercise (Ivy et al., 1988). Glycogen re-synthesis can be optimised further by consuming carbohydrates at a rate of >1.2 g-hour 1 within the first 4 hours after exercise (Burke et al., 2004; Burke et al., 2017a). If such amounts (e.g., 72 g for a 60 kg athlete) are not available or not tolerable, consuming carbohydrates at a lower rate (0.8 g-hour '), but alongside dietary protein (0.3 g-hour-1) will have similar effects on glycogen re-synthesis (Van Loon et al., 2000; Burke et al., 2004). After ~4 hours, normal eating patterns can be resumed, as long as sufficient amounts of carbohydrates are consumed for the rest of the day (Burke et al., 2017a). However, what is deemed ‘sufficient’depends highly on context, with contemporary recommendations highlighting the importance of periodising carbohydrate intake to match daily training demands (Stellingwerff, 2012; Jeukendrup, 2017). As outlined in Chapter 4, it is currently recommended that for low-intensity or short-duration activities (e.g. technical drills sessions or recovery runs < 60 min) athletes should aim to consume 3—5 g-day 1 of carbohydrate, increasing this to 5-7 g-day-1 for moderate-intensity training (e.g., 60 min per day), 6-10 g-day-1 for longer-duration training (e.g. 1-3 hours of activity over the day) or 10-12 g-day-1 in the longest (e.g. 4—5 hours activity over the day) sessions (Thomas et al., 2016).
The glycaemic index (GI) of carbohydrate foods is another important consideration for maximising glycogen re-synthesis following exercise (see Chapter 4). Generally, high GI foods like white bread and jellied sweets are thought to be more effective than low GI foods like wholegrain rice and wholemeal bread at stimulating glycogen-re-synthesis following exercise, owing to the fact they are absorbed more quickly (Moore, 2015). However, if > 8 hours of recovery time is available between sessions, this is less important, as will be discussed.
Glycogen re-synthesis, specifically in the liver, might be further accelerated by consuming carbohydrates that contain a mixture of glucose and fructose (sucrose) post-exercise. Indeed, recent research has shown that post-exercise liver (but not muscle) glycogen repletion is much greater when >1.5 g-hour-1 of carbohydrates are consumed as sucrose, instead of glucose, following exercise (Fuchs et al., 2016). Most foods contain a mixture of glucose and fructose (amongst other sugars); however, fruit juice and fruits (e.g. apples) contain higher amounts of fructose than other carbohydrates like bread and pasta and therefore should be consumed alongside these foods when glycogen repletion is a priority.
The immediate (<8 hours) carbohydrate feeding strategies outlined earlier might not be necessary if: (1) the preceding exercise bout was of low duration (<60 min) and intensity (e.g. recovery run), resulting in minimal glycogen depletion; and/or (2) there are >8 hours recovery time available between training sessions or competition (Parkin et al., 1997; Thomas et al., 2016). In either scenario, if, for example, carbohydrates are not consumed until 2 hours post-exercise, and at 0.6 g-hour-1, glycogen repletion rates should not be compromised before the next session (assuming this is >8 hours away) as long as the overall amount is commensurate with the per-training load recommendations (e.g. 10—12 g-day-1) previously mentioned (Parkin et al., 1997; Moore, 2015).
Protein
It is well established that endurance exercise is a potent stimulator of muscle protein turnover. This process is the balance between (1) removal or remodelling of structural proteins, a catabolic process typically referred to as muscle protein breakdown (MPB); and (2) the synthesis and accretion of new proteins; an anabolic process typically referred to as muscle protein synthesis (MPS) (Mascher et al., 2007; Moore et al., 2014a; Rowlands et al., 2014). While the net balance between MPB and MPS is critical for muscle repair and remodelling following exercise, it is specifically the increase in MPS (as opposed to decrease in MPB) that is thought to be most fundamental to the repair, remodelling and synthesis of functional muscle proteins
(Tipton and Wolfe, 2001; Tipton et al., 2018). As such, maximising MPS in the post-exercise period should be a priority for all endurance athletes.
Dietary protein can augment MPS and the post-exercise anabolic response (Tipton and Wolfe, 2001; Moore et al., 2014a; Macnaughton et al., 2016). The amino acids that make up protein can be used to repair various structures in skeletal muscle, as well as connective tissue like ligaments and tendons (Beelen et al., 2010; Moore, 2015). In addition, recent research (Townsend et al., 2017) has shown that ingesting whey protein (0.5 g-kg of body mass-1; BM) following exhaustive treadmill running exercise (75% of maximal oxygen uptake) attenuates markers of bone resorption, which could have important implications for improving bone health and ultimately reducing stress fracture risk in endurance athletes.
Current recommendations for optimal post-exercise protein intake are individualised to body weight. In the immediate hours post-exercise, 0.25-0.30 g-kg BM-1 of dietary protein (15-18 g for a 60 kg athlete) is likely sufficient to maximise MPS in younger adults (Moore, 2015). In older adults (>50 years), 24 g for a 60 kg athlete might be required for the same effects due to age-related anabolic resistance (Phillips et al., 2016). Ideally, this first feed would be immediately upon finishing exercise; subsequent feeds, of similar quantities (~0.25-0.30 g-kg BM-1, or 0.40 g-kg BM-1 for older adults), should then be repeated every 2—4 hours (Moore et al., 2012a; Areta et al., 2013; Moore, 2015). This pattern of protein intake should aim to equate to —1.2—1.7 g-kg BM day-1 per day (depending on the number of feeds) and is thought to optimise daily MPS and subsequent tissue remodelling in athletes (Moore, 2015).
Different protein sources have different absorption rates and effects on MPS, and therefore the type of protein ingested post-exercise is an important consideration. Animal and dairy- proteins tend to be digested faster and stimulate MPS to a greater extent than non-animal sources (Tang et al., 2009; van Vliet et al., 2015). As such, animal protein such as beef, fish and dairy proteins like whey and casein are preferred to non-animal sources like soy and wheat for maximising post-prandial MPS (van Vliet et al., 2015; Gorissen and Witard, 2018). In the immediate hours post-exercise, whey protein supplements are popular amongst athletes, owing to the rapid absorption and the fact whey contains high amounts of the essential amino acids, especially leucine, that is a potent trigger of MPS (Burd et al., 2012, 2019; Rowlands et al., 2014). However, athletes might be wary that supplements are contaminated with substances banned by the World Anti-Doping Authority'. One way to avoid consuming a contaminated supplement is to ensure any supplements are sourced from a trusted manufacturer who can ratify that their product has been batch tested to not contain banned substances. An informed athlete should buy only from manufacturers that are listed on these databases (e.g. ‘Informed Sport’) and ideally would consult an appropriately qualified sports nutrition professional before purchasing. However, arguably the best way to circumvent these issues is to have a balanced diet that contains the macro-nutrients required to support recovery (see Chapter 4).
Cow’s milk is an excellent option for a convenient and very cheap post-exercise recovery drink. Cow’s milk is a mixture of whey (~20%) and casein (~80%) protein that has been shown to increase MPS to a greater extent than non-animal sources (Wilkinson et al., 2007). Milk has the added benefit of containing carbohydrates and electrolytes that support refuelling and re-hydration goals, respectively (James, Stevenson, et al., 2019b). Furthermore, the current recommended intake of 0.25-0.30 g-kg BM"1 of protein post-exercise can be met with ~400—600 ml of semi-skimmed milk. The wide availability of cow’s milk, its low cost and its high protein content make it an ideal and efficacious choice for maximising postexercise MPS and recovery (James, Stevenson, et al., 2019b).
Sleep is considered integral to psychological and physiological health (Halson, 2014; Watson, 2017). It is widely accepted that part of the function of sleep is to help restore biological homeostasis and central nervous system function. Failure to get sufficient sleep (7-9 hours per night; Watson, 2017) can impair endocrine function, emotion regulation and next-day performance of cognitive and motor tasks, and therefore it plays an important role in optimising function in the next wakeful period (Halson, 2013). Specific to endurance athletes, partial sleep can affect well-being and health and can compromise exercise performance (Halson, 2014; Watson, 2017; Kolling et al., 2019). There is also growing concern that athletes in sleep debt are at an increased risk of musculoskeletal injury (Freitas et al., 2020) that could be attributable to modified immunological responses, where sleep deprivation has been linked to rises in pro-inflammatory biomarkers (Dattilo et al., 2020). In addition, longitudinal research in athletes indicates that poor sleep is inversely correlated with winning competitions (Brandt et al., 2017; Juliff et al., 2018); thus, it is vitally important that athletes get sufficient sleep to optimise recovery, adaptations and subsequent performance.
Sufficient sleep might be of greater importance to endurance athletes than strength and power athletes as partial sleep loss, in which a few hours are lost per night, seems to have a more pronounced negative effect on aerobic performance than muscle strength. In one example, Chase et al. (2017) examined how sleep restriction affected performance in the day following a heavy training session. A group of well-trained male cyclists (ИЭ2тах: >60 mL-kg 'min ') performed >60 min of high-intensity cycling, and resistance exercise followed by a night of normal sleep (~7 hours) or a night of restricted sleep (~2.5 hours). The following morning, muscle soreness and isometric muscle strength were unaffected by the sleep restriction, but 3 km cycling time trial performance was much slower than baseline in the sleep restriction than the control condition (—4% vs. -0.5% slower, respectively). In a further similar example (Rae et al., 2017), power output during a cycling test was impaired in the 24 hours following ~55 min of high-intensity exercise and a night of half normal sleep quantity (3.8 vs. 7.5 hours). The mechanisms behind these negative effects on endurance performance are not entirely clear, but reduced motivation and increased perception of effort has been suggested as likely candidates (Watson, 2017; Halson, 2013; Rae et al., 2017).
Overall, sleep restriction or disturbance will not have a positive effect on performance and recover)', but of course there is likely a high inter-individual variability between athletes (Kolling et al., 2019). Consequently, general recommendations need to be tailored to the individual to determine optimal sleeping patterns (Kolling et al., 2019). Notwithstanding, sleep is undoubtedly important for well-being and health, and thus the most prudent approach, and the one most likely to avoid compromising recovery and exercise performance, is to ensure athletes get 7-9 hours of quality sleep per night and that they feel relatively fresh and ready to perform, especially around competition. For further information on sleep for athletes, the reader is directed to some excellent reviews (Halson, 2014, 2019; Gupta et al., 2017; Kolling et al., 2019).
Contemporary Recovery Strategies Cryotherapy
Cryotherapy reduces tissue temperature and blood flow with the goal to reduce the inflammation and oxidative stress associated with strenuous exercise, and hence further damage
(Merrick, 2002). Consequently, it has attracted a great deal of attention from athletes to facilitate recovery following challenging training and competition (Versey et al., 2013). It can be administered in a number of ways following exercise; typically for athletes, the most common modes are cold water immersion (CWI) and whole-body cryotherapy (WBC). More recent emerging research has investigated the use of phase change material (PCM) that provides a simpler and cheaper method of cooling than more traditional methods.
Cold Water Immersion
CWI is the most commonly used form of cryotherapy and has also been the most researched intervention. Despite this, the body of evidence is far from conclusive, mostly because of confounding issues that make the picture difficult to decipher. This is largely due to the different exercise modes used, the depth and temperature of the water and the duration and frequency of the immersion (White et al., 2014; Vieira et al., 2016). Most CWI interventions are delivered immediately after exercise at 8-15°C. The CWI intervention can often result in reduced soreness and in some cases recovery of dynamic muscle function (Leeder et al., 2012b), although the data from individual studies are quite mixed, with some showing some a positive effect and others showing no effect. Importantly, for runners, there is a general trend to CWI being more beneficial for metabolically challenging exercise like running, and most studies do not show a negative effect, which is an important consideration when applying any intervention (Leeder et al., 2012b).
Water immersions that are colder than 15°C increase discomfort, decrease the time that can be tolerated (Versey et al., 2011) and do not seem to confer any additional benefits (Poppen- dieck et al., 2013). This is worth considering, because the magnitude and duration of cooling (particularly for deeper muscles) will depend on the duration of the immersion. As a general guide, 1 minute for every degree of temperature is a good rule of thumb; for example, a 10 min immersion for 10°C and 15 min for 15°C, and so on. Even for longer immersions, it is not clear if the duration of immersion is sufficient to truly influence recovery in a meaningful way, so if feasible, repeated immersions might have additional benefit. Additionally, it is common to see athletes in rubbish bins as opposed to a seated tub; this is because the pressure can be manipulated depending on the water depth and provide the potential added benefit of hydrostatic pressure (Wilcock et al., 2006). The deeper the water, the greater the pressure, which has been argued to enhance vasoconstriction (Gregson et al., 2011; Mawhinney et al., 2013). This was investigated by Leeder et al. (2015) who showed no additional benefit of seated (30 cm depth) versus standing (120 cm) positions in recovery following a muscle-damaging running activity.
It is also worth noting that CWI can be well tolerated by some athletes, but others find it incredibly difficult to deal with, and it can cause undue stress and anxiety. If the latter is the case, the balance between what you hope to achieve from the intervention and the additional stress it causes the athlete needs to be carefully considered. In general, if an athlete believes the intervention to be of little or no benefit coupled with high stress, it is likely to outweigh any potential benefit that might be achieved.
Whole Body Cryotherapy
WBC involves exposing the whole body to very cold air (-110°C to — 160°C) for durations of 2-4 min in a chamber that resembles a sauna. Historically, it has been used in Eastern
Europe for treating pathological conditions that display pain, oedema and inflammation. In recent years WBC has gained traction as a recovery tool following strenuous exercise by proposing to reduce inflammation (Banfi et al., 2010; Ziemann et al., 2012), muscle damage (Banfi et al., 2009; Hausswirth et al., 2011; Ferreira-Junior et al., 2015) and soreness (Ziemann et al., 2012). The return of function is not clear, although the evidence suggests that immediate exposure to WBC will likely provide a better chance of a positive effect on function (Hausswirth et al., 2011; Ziemann et al., 2012; Ferreira-Junior et al., 2015), while others have shown no difference compared delayed exposure after the exercise (Costello et al., 2012).
A relevant piece of research for runners evaluated the eflficacy of CWI and WBC on performance following a marathon run and showed that WBC negatively impacted the recovery of muscle function compared to CWI. but neither intervention was more or less effective than a placebo (Wilson et al., 2018). In a follow-up study, WBC was found to be more effective than CWI at attenuating soreness and strength following resistance training, but again, neither intervention was more effective than the placebo (Wilson et al., 2019). These studies illustrate that WBC might be less beneficial for running recovery than damaging resistance-type training and therefore the relevance for runners could be questionable. In addition, although there is some promise, the use of WBC is very much for the elite, given that there are very few in situ, they are expensive to use and maintain and they require large spaces to deliver the intervention, making it very difficult to administer. Furthermore, studies indicating that WBC might help to reduce soreness could be attributable to an athlete’s belief and placebo effects; therefore, the cost-benefit to the athlete should be considered when delivering these sorts of interventions.
Phase Change Material
PCM was developed by NASA in 1975, based on prototype work using liquid cooling garments as a method of passively controlling spacesuit temperature when severe temperatures are encountered. Since then, much of the previous human research on PCM cooling has focused on the temperature-regulating effect (Gao et al., 2010) and cooling effect to elicit thermal comfort from heat strain (Barwood et al., 2009; House et al., 2013). In appearance, PCM looks like a standard ice pack but contains a combination of salt and oils that can be altered to change the freeze point. It can be applied directly to the skin surface and easily accommodated under garments for extended periods to treat large muscle masses in a way that is simple to apply, logistically easier and more tolerable for the athlete. The added advantage is that little additional kit is required; it is portable and practicable.
In a novel application of PCM, researchers at Northumbria University, UK, in collaboration with the Nicholas Institute of Sports Medicine and Athletic Trauma in New York, applied PCM to extend the duration of treatment of cryotherapy in exercise recovery. The research has shown that PCM application, with a freeze/thaw temperature of 15°C, can be applied for prolonged durations (3-6 hours) and have a beneficial effect on recovery from damaging exercise (Clifford et al., 2018; Kwiecien et al., 2018; McHugh et al., 2019). Specifically, dynamic muscle function is returned at an accelerated rate and muscle soreness in the days following the exercise is lower. In a very applied study, where professional footballers utilised the intervention after a football match whilst travelling on a bus from away fixtures, there was improved return of muscle function and reduced soreness (Clifford et al., 2018). In addition, the players reported the intervention to be tolerable, and they believed the PCM to be of benefit. The positive influence of the PCM has been attributable to the extended period of cooling that is possible. Whilst the intramuscular temperature at deeper and superficial levels is comparable to CWI, the ability to cool for longer is vastly extended with PCM (Kwiecien et al., 2019). Although further research into recovery from endurance running exercise is required, PCM does hold some promise and is already being used by many elite athletes with some reported success.
Compression Garments
Compression garments are a category of clothing used to provide mechanical support to limbs. These garments are often graduated, with the greatest pressure exerted at the distal aspect of the limb, reducing in pressure towards the proximal aspect; this creates a pressure gradient. The graduated pressure is suggested to improve venous hemodynamics (Ibegbuna et al., 2003) and assist in the maintenance of fluid homeostasis; therefore, these mechanisms could be helpful for managing swelling and inflammation, thereby enhancing exercise recovery. Manufacturers claim that the garments can improve circulation, attenuate swelling and oedema and, in some cases, enhance performance and improve recovery (Trenell et al., 2006; Kraemer et al., 2010; Bottaro et al., 2011).
The use of compression garments in sport has become increasingly popular due to various claims surrounding their benefits (Hill et al., 2014). However, evidence for the efficacy of compression garments in alleviating symptoms of muscle damage is equivocal with studies both supporting (Jakeman et al., 2010; MacRae et al., 2011) and refuting the use of garments. MacRae et al. (2011), in their descriptive review on compression garments, indicated that discrepancies in findings might be due to differences between studies in the populations, modality of exercise, degree of compression, type of compression garment and duration of treatment. However, a more recent and comprehensive meta-analysis showed that compression garments can reduce muscle damage indices such as soreness and accelerate recovery of muscle function (Hill et al., 2014), but the most positive effects were following resistance-type exercise. A subsequent meta-analysis (Brown et al., 2017) was able to break down all types of exercise and delineate between cycling, running and resistance training. This work showed some benefit in performance from endurance activity like running and improved recovery from running-based activities.
Despite the widespread use of compression garments, the evidence is not overwhelming, but on balance they certainly do not have a negative effect. A question that has arisen from the recover)' literature is the discrepancy between study design, compression of the garments and length of administration. This was systematically researched by Dr Jess Hill who showed that commercially available compression garments in general do not exert sufficient pressure, and often fall some distance short of the recommended compression needed for a physiological effect (Hill et al., 2015). This highlighted that many of the previous studies might be invalid because the compression from the garments worn might have been insufficient. In a recent study, custom-fitted garments were used to examine recovery after repeated sprint running and were shown to reduce muscle soreness and improve muscle function in comparison to a control group and ‘off the shelf’ garments (Brown et al., 2020). Collectively, it seems that the use of compression garments used immediately after running might be of benefit to support recovery, but care should be exercised to ensure the garments are appropriately fitted and provide sufficient compression.
Stretching
Stretching is normally used to increase flexibility and joint range of motion (Weerapong et al., 2005) and is a common practice in sporting environments due to the belief that it can reduce the risk of injury and improve performance (LaRoche and Connolly, 2006; Behm and Chaouachi, 2011). Whilst there is good evidence that stretching can help increase flexibility and joint range of motion, it has also been proposed to be effective in the recovery process to reduce muscle soreness and muscle stiffness (Torres et al., 2007). Several review articles suggest stretching can bring about changes in muscle-tendon length and stiffness and hence improve flexibility (Reisman et al., 2005; Weerapong et al., 2005; Behm and Chaouachi, 2011). These changes could then assist in reducing the negative effects of strenuous training and competition. Some support for this was shown by LaRoche and Connolly (2006) who showed that a 4-week stretching programme was able to maintain flexibility following damaging exercise, although no change in muscle soreness was seen. Likewise, others have observed that an 8-day stretching protocol consisting of three, 30 sec passive stretches of the quadriceps muscle group did not affect markers of recovery; but conceptually, the stretch duration could be insufficient to provide a benefit (Lund et al., 2007). Collectively, the research findings suggest that stretching before or after exercise provides little or no benefit for recovery (Henschke, 2011). Although there is a good rationale for the use of stretching for runners in developing some physical attributes (flexibility) and injury prevention (Barnett, 2006), it is probably of little use in assisting in recovery beyond being part of habitual warm-up, cool-down or stand-alone session activities.
Massage
Massage is a very popular intervention to help support exercise recovery. In fact, there are few athletes at the elite level that do not have a massage therapist to utilise massage as a recovery tool. Despite the obvious widespread use of massage, the supporting evidence is thin in the extreme. Massage has been used in an attempt to reduce muscle soreness from strenuous exercise, although studies have found little or no benefit in post-exercise massage therapies compared to rest only. In a well-controlled study Smith et al. (1994) showed a significant reduction in soreness when massage was administered 2 hours post-exercise. These significant observations were attributed to a disruption in inflammatory cell accumulation and hence a reduction in pain (Smith et al., 1994). Conversely, Gulick et al. (1996) found the signs and symptoms of delayed onset of muscle soreness were not abated when massage was applied after a damaging bout of eccentric exercise.
It is very difficult to draw comparisons between investigations due to methodological discrepancies in treatment time and the techniques used. Perhaps by examining specific techniques, an effective massage method and duration for reducing symptoms of exercise induced muscle damage (EIMD) might be achieved. In a recent addition to the literature, Monteiro Rodrigues et al. (2020) showed that a short bout of effleurage massage increased blood perfusion and hence showed evidence of improved microcirculation. However, realising these potential physiological changes in athletes is not easy to detect. For example, in a randomised trial of 78 runners, massage was shown to have a small positive effect on thigh pain after training, but there were no performance changes (Bender et al., 2019). There are numerous examples of modest changes in soreness in the literature, but clear physiological benefit is not evident. What is certainly true of massage is that many athletes ‘feel’ better, which cannot be underestimated. The simple therapeutic armamentarium of ‘laying on of hands’ can be of benefit to the athlete in supporting recovery.
Foam Rolling
Over the last decade or so, foam rolling has gained enormous popularity in athletic arenas. It is difficult not to trip over foam rollers in strength and conditioning (S&C) facilities, and athletes are often armed with a foam roller during training. There are suggestions, particularly within the S&C community, that foam rolling might increase training efficiency, competition preparation and accelerate exercise recovery. But is there any evidence to support their use, or are they just the Emperor’s new clothes? Foam rolling is predominantly used as tool for self-massage where body weight is used to apply pressure to different parts of the body (often muscle and other soft tissue; Pearcey et al., 2015). It certainly is time-efficient and provides an easy and cost-effective intervention that is akin to massage and hence is attractive to athletes; however, the athlete belief in the benefits of foam rollers might actually exceed any physiological benefit. This is not necessarily a bad thing, as long as there is certainty (like all recovery strategies) that it is not having a detrimental effect.
The supporting evidence for the use of foam rolling for recovery is very thin, and there is no consensus on the efficacy of this intervention (Cheatham et al., 2015; Pearcey et al., 2015). The possible benefits are attributed to mechanical, neurological, physiological and psychophysiological underpinnings (Wiewelhove et al., 2019). Collectively, these factors are thought to be influenced by the manipulation of tissue, an analgesic effect, altering blood flow, an increase overall well-being and a potential placebo effect (Phillips et al., 2018). In a recent systematic review with meta-analysis, Wiewelhove et al. (2019) explored the effect of foam rolling on performance and recovery. Only a few studies were identified, some of which were considered of limited quality, which led the authors to suggesting there is no consensus on the optimal duration, pressure and frequency for foam rolling. They showed some benefit of foam rolling conducted before exercise on sprint performance and flexibility. However, with the exception of modest changes in muscle pain, there were no benefits on post-exercise recovery (Wiewelhove et al., 2019). Based on these data, foam rolling does not seem to have any negative effects, but any real benefits in exercise recovery might also be limited.
Dietary Supplements
If recovery time between important training sessions or competition is limited (e.g. <72 hours), runners might consider additional dietary supplements to help alleviate some of the symptoms of EIMD. Of the research conducted to date, the category of supplements showing the most promise are the so-called ‘functional foods’. These foods typically refer to plant foods that are naturally rich in anti-inflammatory and antioxidant phytonutrients. Because strenuous exercise evokes a transient but robust inflammatory response, which involves the release of reactive oxygen and nitrogen species (also known as free radicals), these cellular processes are thought to contribute, at least in part, to the symptoms of EIMD. Thus, the rationale for consuming these supplements is that they might mitigate some of free radical or inflammatory related damage to structures involved in muscle force production during high intensity exercise (Paulsen et al., 2014a; Reid, 2016).
To date, functional food supplements have shown more promise than the traditional agents (vitamin C and E or non-steroidal anti-inflammatory drugs) purported to aid recovery via these mechanisms (Myburgh, 2014; Lundberg and Howatson, 2018; Marika et al., 2019). Indeed, cherry juice (Howatson et al., 2010; Bell et al., 2015, 2016; Brown et al., 2019), blueberry juice (McLeay et al., 2012), pomegranate juice (Trombold et al., 2010, 2011; Machin et al., 2014) and turmeric (Drobnic et al., 2014; Nicol et al., 2015) have all been shown to help alleviate some of the symptoms of EIMD. For a detailed overview of all the functional foods that have been examined for their potential to attenuate EIMD, the interested reader should consult a recent article on the topic (Bowtell and Kelly, 2019). The rest of this section will discuss only dietary supplements with the most evidence to support their effects as recovery aids following strenuous exercise.
To date, cherry juice has probably shown the most promise for aiding recovery from endurance-type exercise. The benefits of cherries are thought to stem from their high concentrations of phytochemicals, especially anthocyanins, which have potent antioxidant antiinflammatory effects (Bell et al., 2014; Keane et al., 2016). In a study by Howatson et al. (2010), cherry juice ingestion before and after the London Marathon attenuated markers of inflammation and accelerated the recovery of isometric muscle strength in the 2 days following the race. Subsequent studies confirmed these beneficial effects in endurance cyclists (Bell et al., 2015, 2016). In the latter of these studies, cherry juice ingestion enhanced muscle function recovery in the three days following 110 min of high-intensity cycling exercise. Thus, cherry juice might be a useful supplement to expedite recovery following high-intensity training sessions or long duration races that evoke symptoms of EIMD.
Curcumin, a phytochemical from the turmeric root, has also shown promise as a recovery aid following strenuous exercise. Like cherries, curcumin is thought to aid recovery via antiinflammatory and antioxidant mechanisms (Drobnic et al., 2014; Fernandez-Lazaro et al., 2020). Several studies have shown that curcumin reduces the activity of nuclear factor kappa B, a transcription factor that upregulates pro-inflammatory mediators associated with muscle damage (Thaloor et al., 1999; Sahin et al., 2016). Drobnic et al. (2014) were the first to examine the effects of curcumin supplementation on markers of EIMD. They showed that taking curcumin (200 mg-day-1) 2 days before and 4 days after 45 min of downhill running, which evoked significant muscle damage, reduced delayed onset of muscle soreness, systemic levels of inflammation and structural damage to the thigh musculature. Since this study, there have been several others suggesting that curcumin supplementation reduces markers of muscle damage following strenuous exercise, ostensibly by reducing inflammation and free radical-mediated damage, also known as oxidative stress (Nicol et al., 2015; Tanabe et al., 2015; Basham et al.,
- 2019) . Although not all studies report beneficial effects, a recent systematic review of the literature suggested that on the balance of available evidence, curcumin appears to be a safe and efficacious supplement for attenuating symptoms of muscle damage (Fernandez-Lazaro et al.,
- 2020) . Runners who often suffer from symptoms of damage (muscle soreness, stiffness, loss of muscle function) might consider supplementing with curcumin a few days before and after key training sessions and events in which rapid recovery is a priority.
Not all dietary interventions shown to alleviate symptoms of EIMD are rich in phytochemicals. There is emerging evidence that omega-3 polyunsaturated fatty acids, enriched in fish oils, have an important role in the regulation of muscle tissue and recovery from exercise (Tachtsis et al., 2018). The major mechanism by which fish oils could influence recovery is via modulation of the acute inflammatory response following strenuous exercise (Philpott et al., 2019). Indeed, studies have found that lipid mediators derived from fish oil, collectively known as resolvins and protectins, reduce inflammatory responses, which helps to facilitate homeostasis (Seki et al., 2010; Serhan and Petasis, 2011).
In clinical populations, omega-3-rich fish oils and their derivatives have long been known to reduce symptoms of muscle and joint pain and are considered useful adjuvant analgesics (Goldberg and Katz, 2007; Lee et al., 2012). However, only in the last decade have studies emerged suggesting that they can reduce muscle soreness, inflammation, and other deleterious symptoms associated with muscle damaging exercise (Philpott et al., 2019). For example, DiLorenzo et al. (2014) found that taking fish oil (2 g-day ') for 28 days prior to and 2 days following eccentric exercise with the elbow flexors reduced blood markers of inflammation and damage but did not benefit soreness or recovery of muscle function. More recently, Philpott et al. (2018) examined if 6 weeks of daily fish oil (1100 mg) and whey protein supplementation would enhance recovery following eccentric exercise of the knee extensors. They found that creatine kinase and soreness were lower in the 72 hours following exercise in subjects taking the fish oil-whey protein beverage. However, like in the study of Di Lorenzo et al. (2014), strength was unaffected, suggesting that fish oil might expedite the recovery of some but not all markers of muscle damage.
A recent review acknowledged that fish oil holds promise as a recovery aid but cautioned that the overall evidence to support these effects in athletes is moderate at present (Philpott et al., 2019). They did point out that consuming large amounts of omega-3 in the diet or via a fish oil supplement does not appear to be detrimental to recovery or adaptation. This is important because > 2 weeks of supplementation is required to detect a marked increase in omega-3 fatty acid levels and, thus, anti-inflammatory effects might not be realised with lower doses (Philpott et al., 2019). Another important yet unresolved issue is the optimal daily dose required. Benefits have been seen with 1-4 g day 1 which might not be achievable via diet alone; hence, fish oil supplements are often used in research and are recommended for optimal effects (Philpott et al., 2019). Thus, from a practical point of view, if planning to use fish oil to expedite recovery, a supplement might be required, and it should be consumed several weeks in advance for optimal effects.
Exercise Adaptations
It is important to note that some scientists caution against the use of recovery interventions that interfere with exercise-induced inflammation or free radical production (Paulsen et al., 2014a). This is due to the emerging role of inflammatory processes and free radicals such as hydrogen peroxide in stimulating exercise adaptations. Indeed, some have observed that supplements with antioxidant functions interfere with mitochondrial biogenesis (Paulsen et al., 2014b; Morrison et al., 2015), raising the possibility that these supplements could blunt training-induced adaptations important for endurance performance, like an enhanced K02max. At present, the vast majority of studies have been conducted with vitamin C and E as opposed to non-steroidal anti-inflammatory drugs or functional foods. Although there is evidence that vitamin C and E might blunt training-induced changes in aerobic capacity of rats (Gomez-Cabrera et al., 2008b), there is currently a lack of evidence supporting similar impairments with antioxidant-like supplements in humans (Yfanti et al., 2011; Paulsen etal., 2014b; Peake et al., 2015). A review by Peake et al. (2015) concluded that while vitamins C and E appear to blunt some molecular changes induced by endurance type exercise, the evidence that this translates to changes at the performance level is lacking. This position was supported by a recent meta-analysis that found there was no effect of long-term vitamin C and E supplementation on training adaptations associated with endurance performance (Clifford et al., 2019). Therefore, there is currently insufficient evidence to suggest that dietary supplements with antioxidant functions will blunt training adaptations. Importantly, these interventions do not extinguish inflammation and oxidative stress, but rather reduce the magnitude. This calls into question whether high levels of inflammation and oxidative stress are necessary, and perhaps only small increases are required to get the requisite adaptative signalling response.
The approach recommended here is to view the usefulness of antioxidant and functional food supplements, particularly with regards to recover)'; as highly context dependent. For instance, their chronic use throughout a preparatory phase of season might interfere with molecular signalling processes and possibly hinder longer-term training adaptations. However, the acute use of these supplements, when the need to minimise the adverse effects of performance (i.e. soreness and losses in muscle function) far outweigh the need for adaptation, could form part of a recovery strategy to restore optimal performance and/or reduce any lingering discomfort. One way to conceptualise this is the use ofhormesis (Figure 17.2). In simple terms, the exercise stress imposed by training is relatively linear, insofar as the more you do, the better you are likely to get. However there comes a point when further increases in intensity or volume can become maladaptive because the level of inflammation and oxidative stress is very high, for example. This is the conceptual point when additional help in the form of recovery strategies can support athletes to reduce the potential for maladaptation or performance decreases. The other time to implement recover)' strategies is when baseline cannot be naturally achieved in the requisite time. A good example might be when there is competition congestion and several rounds or races must be completed in a short period of time when there is insufficient time to completely recover.
FIGURE 17.2 Theoretical hormesis curve. As the dose of exercise increases, so too does the positive effect from exercise. There comes a point where exercise dose can induce maladaptive effects, and this is the conceptual point where recover)' interventions might be of benefit
Athlete Belief and the Power of Placebo
As alluded to throughout this chapter, an important consideration in the application of interventions is athlete belief. This is particularly pertinent given that a growing body of evidence indicates that recovery is related to individual preference and perceptions of the intervention. Practitioners must recognise and manage the influence of the belief and placebo effects if the application of recovery strategies is to be successful. Given the need to achieve coach and athlete buy-in to any intervention, there is an obvious challenge to balance an evidence-based approach with the beliefs and expectations of coaches and athletes (Halson and Martin, 2013). In cases where an athlete believes in a particular recover)' strategy despite a lack of supporting scientific evidence, the demand on resource (financial, time, effort), the cost (i.e. what is sacrificed by engaging in a particular strategy) and critically, the potential for harm or a negative performance effect, must be evaluated. On balance, if there is no negative effect and the athlete believes in the intervention, then, even in light of little supporting evidence, the intervention could actually be beneficial. It is therefore important to use recovery strategies on a very individualised basis to ensure the most benefit can be gained from an intervention.
Summary
Training sessions and competitions cause transient impairments to performance that results from a variety of physiological disturbances. During the recovery process that ensues following exercise, a range of interventions could be utilised with the aim of improving physiological adaptation, reducing physiological stress and/or enhancing recovery time. Addressing the basics - hydration, sound nutrition and adequate sleep - should form the priority of any runner’s recovery routine. It is highly unlikely that any other recovery strategy will be beneficial unless these three pillars of recovery are adequately met. Beyond these important macrostrategies, other recovery interventions (i.e. cryotherapy, compression garments, ‘functional foods’) may also offer some benefits. These recovery strategies can make a positive influence on returning athletes to the basal state but should be used judiciously depending on the focus of the individual, the training volume, time available for recovery and the focus of the training stress. Many practitioners and elite runners currently implement recovery strategies during championship situations or after specific training sessions when performance in the subsequent rounds of competition or training sessions is of paramount importance. In contrast, the use of recovery strategies could be limited or avoided when long-term physiological adaptation to the training-induced stress is the priority. Finally, the importance of athlete belief in the intervention should not be underestimated, because despite limited evidence for physiological benefit in some recovery techniques (e.g. stretching, foam rolling, massage), these interventions can still be beneficial due to the power of placebo.
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