Nutrition support for injury management and rehabilitation
Injuries are an unfortunate reality of both recreational and professional sports. In 2011–12, the Australian Institute of Health and Welfare (AIHW) reported that 36,000 people aged over 15 years were hospitalised as a result of a sporting injury (AIHW 2014), with the annual cost of sporting injuries in Australia estimated to be over $1.5 billion (Medibank 2003). At an elite level, the impact of sporting injuries can be significant, often having various physical, psychological, professional and economic consequences for both the athlete and the organisation that contracts them. Injuries range from minor (cuts and abrasions), through moderate to severe (such as musculoskeletal and connective tissue injuries), including the small number that have life-long implications (for example, concussion). Depending on the type and severity of injury, the consequences may range from immediate but short-term cessation of sport to weeks, months or even years away from training and competition.
While rehabilitation strategies have been developed in physical therapy, medicine and psychology, nutrition interventions are often focused predominantly on controlling body composition. However, nutrition interventions outside of body composition management can play an important role during the rehabilitation phase for an injured athlete, and can influence their ability to return to training and competition. Nutrition strategies for injury rehabilitation should focus on supporting tissue regeneration, attenuating the effects of immobilisation on the musculoskeletal system and minimising unnecessary body composition changes associated with reduced training loads. Finally, and most importantly, any rehabilitation program should ensure the athlete is returned to competitive sport in a state that is similar to or better than pre-injury functioning where possible. The following chapter will give an overview of nutrition considerations in the management of injuries.
LEARNING OUTCOMES
Upon completion of this chapter you should be able to:
• understand the influence adequate nutrition has in preventing load-related injuries
• understand the timeline of injury rehabilitation and the nutrition considerations at each time point of the rehabilitation timeline
• understand nutrition support for assisting the athlete in ‘return to train and then play’
• have an awareness of emerging nutrition interventions related to injury prevention and rehabilitation.
TYPES OF INJURIES
The types of injuries that occur within a sport are generally related to the characteristics of that particular sport. For example, contact sports, including rugby union, rugby league and Australian football, commonly result in injuries as a result of body contact and/or sudden directional changes, often involving musculoskeletal and/or connective tissues. Sports such as boxing commonly result in injuries as a result of a direct ‘hit’ or ‘blow’ to the body and may result in skin lacerations, fractures, dislocations or concussions. Athletes participating in endurance sports, such as long-distance running and triathlon, are often faced with injuries such as tendinopathies, which may be attributable to poor load management and over-use of a specific tissue. We will focus here on the most common injuries occurring in sport. These include injuries to the bone (fractures), soft tissues (including cartilage, ligaments, tendons and muscle) and ‘other’ injuries (including injuries to the head and skin). It should be noted that injuries rarely occur in isolation and often involve multiple components of the body.
Tendinopathies
Diseases of the tendons, which may arise from a range of internal and external factors.
The term ‘fracture’ encompasses any injury in which a bone becomes cracked or broken, and fractures are the most common type of sports injury requiring hospitalisation, accounting for almost 50 per cent of injuries within Australia (AIHW 2012). Fractures can occur as an acute injury—due to a sudden impact such as contact with another person, obstacle or a fall—or as a result of repeated stress to the bone, as is the case for stress fractures. Acute fractures can occur in almost any sport where there is some form of direct contact with another person or object, or if there is a risk of a fall, such as in football, cycling, running, combat sports, snow and water sports, equestrian activities and motor sports. While stress fractures tend to occur over time, they are common in sports where loading can change quickly, such as watercraft sports (rowing, kayaking), running, gymnastics, ballet, basketball and volleyball. While it is important to focus on the adequacy of key nutrients (such as calcium and vitamin D) that may assist with bone healing, preventing nutrient deficiencies and ensuring adequate energy intake (see section on RED-S and energy availability below) is an important consideration for the prevention of bone injuries.
Soft-tissue injuries
Soft-tissue injuries refer to injuries to the musculoskeletal and connective tissues, whether acutely, such as a sprain/ strain or tear, or chronically, as in the case of tendinopathies. Soft-tissue injuries were the second most common type of injury requiring hospitalisation, according to the AIHW 2011–12 report. Sports characterised by high-speed movements and change of direction have a high incidence of soft-tissue injuries resulting from tears, ruptures and strains. These types of injuries are typically sustained while undertaking high-speed running—with or without a quick change of direction—which places significant strain on tissues incapable of handling the load. The duration of recovery can range from days to a year, depending on the severity of the injury. However, in sports where athletes increase load rapidly over days or weeks, more chronic conditions like tendinopathies develop. Specifically, the pain and dysfunction resulting from a tendinopathy can significantly interfere with the capacity to train and compete. Tendinopathies are complicated and do not have a common pathology, so the treatment of tendinopathies will often be specific to the tendon and the athlete’s injury history. Consequences of soft-tissue injuries can range from reduced load for a period of a few days to inability to complete certain types of exercise for the rest of an athlete’s life.
Pathology
A field in medicine which studies the causes of diseases.
Other injuries
Head injuries are frequently reported in contact sports. Symptoms can be as minor as short periods (minutes) of memory loss to long-term impairment in brain function. Recently, this long-term impairment in brain function has been linked to multiple acute head injuries and subconcussive impacts. Researchers are investigating numerous interventions, including the influence specific nutrients (important for brain function) can have on helping the brain regenerate or cope with these types of injuries. Other injuries, such as skin lacerations (deep cuts) are also common in sport and present significant concern in sports where dietary adequacy may influence wound healing or in events where treatment options may be limited, such as multi-day ultra-endurance running events.
Subconcussive
A hit to the head that does not meet the clinical criteria for concussion, but is hypothesised to have long-term adverse effects.
Special interest area: Concussion
Concussion is a type of traumatic brain injury (TBI) generally caused by a violent blow to the head and resulting in temporary impairment of cognitive function, including loss of consciousness, vision, memory and equilibrium (balance). Short-term symptoms include diminished reaction times, headache, irritability and sleep disturbances. Repeated concussive injuries have been linked to chronic traumatic encephalopathy (CTE), a progressive degenerative disease of the brain. Often referred to as ‘punch drunk syndrome’ in retired boxers, it can eventually result in dementia. Under normal conditions, the human brain accounts for around 20 per cent of the oxygen and 25 per cent of the glucose utilised by the body (Belanger et al. 2011). However, after a concussion there is a cascade of functional disturbances within the brain, including alterations in energy, glucose and lactate metabolism, increased oxidative stress and inflammation, which may make the brain more susceptible to secondary injury and/or lead to future complications (Giza & Hovda 2014). Presently, the only treatment for concussion is physical and cognitive rest until acute symptoms are resolved.
Although nutrition interventions for TBI are still being explored, research to date suggests that antioxidants and anti-inflammatory agents may be of benefit. Emerging evidence suggests that omega-3 fatty acids (n-3 FA), particularly docosahexaenoic acid (DHA) (see Chapter 4) may play a role in both prevention and treatment of TBI. In animal models, depletion of DHA within the brain impairs recovery from TBI. Additionally, supplementing with n-3 FA prior to sustaining a concussion has been shown to protect against impact sustained from a concussion. Athletes at risk of frequent head collisions should regularly include cold-water fatty fish in their diets at least three times per week. Other nutrients that may play a role in the treatment of TBI include vitamins C, D and E, through the reduction of oxidative damage, and creatine, whose levels decrease within the brain after concussion. Although further research is needed in athletic populations, the nutrients suggested as beneficial are easily obtained from dietary sources. Therefore, athletes competing in contact sports should be encouraged to consume foods high in the above nutrients as part of their well-planned sports-specific intake (Ashbaugh & McGrew 2016).
Docosahexaenoic acid
A long-chain n-3 fatty acid with 22—carbons and six double bonds, found in fatty fish and breast milk.
PHASES OF NUTRITION INTERVENTIONS FOR INJURIES
Typically, acute injury begins with the process of acute inflammation, followed by a potential period of immobilisation and a varying period of rehabilitation before returning to training and subsequently competition. Nutrition plays a critical role in each phase of this injury rehabilitation process, as outlined below. Although it is tempting to suggest nutrition will have a large impact on injury rehabilitation, its key role is in supporting the rehabilitation program designed by a physician, physical therapist or rehabilitation specialist. Nutrition will boost the repair process but the interventions will only be as successful as the program they are designed to support; thus, a multidisciplinary approach to support rehabilitation of the injured athlete is essential.
Injury prevention
While nutrition support plays an important role in injury rehabilitation, it is also important to consider that adequate nutrition plays a critical role in the prevention of injuries. It has long been known that significant acute changes in training load can lead to a range of injuries. It is not known whether the primary issue is the increase in load or the inability of athletes to change their dietary intake to meet the requirements of the increased load. An International Olympic Committee (IOC) working group has suggested that the inability to match energy intake to account for variations in the energy cost of exercise contributes to injury risk (Mountjoy et al. 2014). It is therefore essential that energy intake rises and falls in tight response to training load. Additionally, special focus should be given to ensure adequate nutrient availability necessary for the significant increase in remodelling that is associated with increased training load. Adequate intake of protein, carbohydrate, and calcium, timed closely to heavy training, has been shown to positively influence the remodelling process, reducing the breakdown of tissues such as bone that occurs after heavy training sessions. Nutrition recommendations for athletes undertaking increased load should focus on adequate energy availability combined with purposeful nutrient availability, to aid in the prevention of load-related injuries.
Special interest area: RED-S and energy availability
As previously discussed in Chapter 18, appropriate energy availability (EA) is particularly important for athletes. Reports suggest a healthy adult has a typical EA of 188 kJ/kg of fat-free mass (FFM). However, when EA drops below a threshold of 125 kJ/kg FFM (low energy availability), insufficient energy is available after exercise is accounted for to maintain key functions such as the immune system, bone remodelling, protein synthesis and hormonal functioning.
Relative energy deficiency in sport (RED-S), as a consequence of long-term low energy availability (LEA), has a range of implications for athlete health and a particularly large effect on bone remodelling, mostly due to the influence LEA has on oestrogen and its flow-on effect of reducing IGF–1 (Mountjoy et al. 2014). IGF–1 is a hormone that is essential for stimulating remodelling cells in the muscle, bone and connective tissue. It has also been shown that muscle protein synthesis is reduced during periods of LEA, but increasing the amount of protein consumed around exercise minimises those reductions (Areta et al. 2014). This highlights that LEA influences the remodelling of proteins in both bone and muscle tissues, potentially increasing the risk of injuries in these tissues. More work is needed to understand whether improving nutrient availability around exercise while in a state of LEA can potentially reduce the negative impact of LEA on bone, muscle and connective tissue synthetic processes. This complex and wide-reaching area of nutrition should be closely monitored and not discounted in the prevention of injuries. The primary focus of nutrition interventions as training loads increase should be ensuring that adequate EA is maintained to reduce the risk of injury.
The initial phase of injury (immobilisation)
After any injury the body’s natural response is to increase inflammation (swelling), signalling the requirement for repair and remodelling. The management of chronic low-grade inflammation has been a major focus of lifestyle disease prevention in recent times; however, acute inflammation associated with injury is an important process that helps signal and stimulate remodelling. Evidence to support the use of anti-inflammatory nutrients to suppress inflammation, and hence improve injury rehabilitation, is lacking (Tipton 2015). In fact, in the short term (the period of the first few hours to days of an injury) it may be detrimental to reduce a response that is necessary for the healing and repair of damaged tissue.
Most injuries require some form of disuse, or even immobilisation, with acute tears and ruptures often requiring immobilisation for days to weeks. This immobilisation leads to significant reductions in energy expenditure. Often the first instinct of athletes is to reduce energy intake proportionally. However, during the initial phases of any injury, energy requirements may actually be increased due to energy demands for the proliferation and remodelling of injured tissue (Tipton 2015). This could be combined with the increased energy cost of abnormal movement patterns, especially with lower leg injuries. Therefore, severe energy restrictions leading to poor nutrient availability (especially protein) should be avoided, particularly in the first five days following injury and immobilisation. During this phase of injury, athletes are recommended to not actively restrict dietary intake, maintaining energy intake between 146 and 188 kJ/kg/FFM. They should focus on reducing carbohydrate intakes to the lower end of the guidelines (~3 g/kg BM/day) and maintain protein intake at 2–2.5 g/kg BM per day, spread evenly over all meals and snacks.
If immobilisation is expected for extended periods (>5 days) athletes are advised to implement nutrition strategies that help offset muscle wasting associated with disuse. Recent studies in this area have found that it is necessary to maintain an exercise stimulus when providing additional nutrition support to minimise muscle wasting associated with disuse or immobilisation. Recommendations should be to include high-leucine (~3 grams) protein sources (>16 grams of essential amino acids) at all meals and snacks over the day. This is especially important with exercise regimes capable of maintaining a stimulatory effect (such as electrical muscle stimulation) and can be effective at reducing muscle wasting (Dirks et al. 2017). Although traditionally the focus has been on minimising loss of muscle mass and function, connective tissue volume and function has also been shown to deteriorate rapidly when immobilised. Recently, novel nutrition interventions, such as gelatin, have been suggested to help support these tissues during immobilisation; however, more research is needed before definitive interventions can be recommended (Baar 2017).
Leucine
An essential amino acid, which is required for muscle protein synthesis.
Other nutritional interventions targeted at overcoming the anabolic resistance that occurs with disuse—such as omega-3 fish oils, creatine, b-Hydroxy-b-methylbutyrate (HMB, an active metabolite of the branch chain amino acid leucine), and other chemicals that play a key role in the muscle protein synthetic pathway (such as phosphatidic acid)—may be useful; however, the evidence for their use requires more investigation (Wall et al. 2015). Nutrition recommendations for injuries that require periods of immobilisation should be focused on ensuring adequate energy availability in combination with optimal total protein intake (>2 g/kg BM). High-leucine protein sources should be consumed every 2–3 hours throughout the day to maximally support optimal protein synthesis, especially in the early stages of injury. These interventions will be most effective when combined with sufficient exercise of the injured tissue to maintain at least a modest amount of protein synthesis.
Special interest area: Nutrition for chronic inflammation
While acute inflammation is a necessary and natural process of the body’s immune system in response to initial tissue injury, chronic inflammation can lead to persistent pain and has the potential to contribute to long-term damage within the tissue. Dietary sources of anti-inflammatory nutrients are highly effective at maintaining inflammatory processes within manageable ranges. It has been suggested that a low ratio of omega-3 (n-3) fatty acids (found predominantly in marine sources) to omega-6 (n-6) fatty acids (found in processed foods and some seeds, nuts and oils) leads to an imbalance in the control of inflammation within the body. Recommendations to manage this imbalance are to limit processed foods and seeds/nuts/oils high in n-6 while increasing intakes of dietary sources of n-3, such as oily fish (Simopoulos 2002). There is also an increasing focus on the bioactive components of plant-based foods that may assist in reducing inflammation, such as polyphenols. Polyphenols of interest include epigallocatechin (EGCG) (found in green tea), curcumin (found in turmeric) and rutin (found in a wide variety of plants, including apples and citrus fruits). While research is continuing to develop and evolve around the bioactive components of food, athletes may be able to help manage unwanted inflammation by ensuring that they consume a diet rich in plant-based foods.
Polyphenols
A group of over 500 compounds that are found in plants. They are important as they provide protection against disease.
The second phase of injury (return to train)
After the initial phase of disuse is completed and athletes are able to use and train the injured muscles or limb, nutrition focus should shift. Nutrition in this phase of injury rehabilitation will focus on maximally supporting the training stimulus to rebuild muscle and connective tissue to pre-injury levels. If nutrition and training strategies have been strategically implemented, muscle wasting as a result of disuse should have been minimised to no more than a few hundred grams. As per traditional training nutrition strategies, nutrition should firstly be targeted at meeting energy availability. During the initial weeks of this phase of rehabilitation, energy intake will still be lower than normal as total training load is still low. However, depending on the injury, this phase of rehabilitation may still include full-load resistance training of uninjured tissue and aerobic training using uninjured muscles and limbs (bike for upper body injury, grinder or similar for low body injuries). Therefore, careful thought should be given to energy intake as over- or underestimating energy expenditure during this period of rehabilitation can lead to suboptimal changes in body composition (fat mass increase, lean mass loss).
Rehabilitation periods are often utilised as opportunities to address physique insufficiencies. Although it may seem intuitive to manipulate body composition during extended rehabilitation periods, athletes and practitioners should ensure any gains in lean mass are achieved concurrently with appropriate increases in training loads.
Macronutrient goals should be re-aligned with typical training recommendations, with protein intakes between 1.4 and 2 g/kg BM per day; carbohydrate intakes matched to the training undertaken on a day-to-day basis; and fat intake from quality sources focused on meeting energy requirements. Dietary supplements such as creatine, caffeine, beta-alanine and sports foods, if used, should be focused on supporting training capacity and enabling athletes to improve training performance, hence retraining injured muscles quickly back to pre-injury strength and metabolic capacity.
The third phase of injury (train to play)
Once an injured muscle, joint or limb has returned to pre-injury function and size, the nutrition focus should shift from synthesis and regeneration to amplifying the adaptive signal of exercise. Over the last ten years, significant research has demonstrated that the provision or restriction of specific nutrients can help amplify the biochemical signalling of exercise. For those athletes looking to fast-track aerobic adaptations, manipulating carbohydrate availability around training has been shown to be a potent stimulator of aerobic adaptation. Strength, power and team sport athletes may benefit from dietary interventions focused on enhancing high-intensity training volumes. Small, purposeful carbohydrate intakes prior to exercise, combined with supplements that enhance training capacity (such as creatine, beta-alanine, nitrates and caffeine) can enhance work completed during training if used strategically, hence fast-tracking the physiological adaptations achieved from training (see Chapters 12 and 15).
The fourth phase of injury (return to competition)
Athletes who have completed a rehabilitation program through the above stages and are deemed ready to compete should no longer require additional or specific nutrition requirements. Nutrition recommendations should follow those of healthy non-injured athletes. Injured limbs or muscles should be returned to similar, if not enhanced, muscle size and function prior to return to competition and should not require ongoing nutritional support.
However, injuries, especially to joints, can often place significant strain on both the injured and other non-injured joints, leading to degenerative conditions such as osteoarthritis. Although numerous nutrition interventions have been suggested to either treat or alleviate the symptoms of these conditions (glucosamine, fish oils, curcumin, hydrolysed collagen) the evidence for their use is still equivocal and requires more research. Athletes should maintain an appropriate body weight throughout the rest of their career and then throughout their adult life, to avoid placing unnecessary load on the injured joint and increasing the risk of developing a degenerative joint condition.
Osteoarthritis
A degenerative condition of the joints that occurs when the cartilage in the joint degenerates, which leads to loss of function.
Table 24.1. Overview of rehabilitation and nutrition planning for the injured athlete
| Time (week) | ||||
| Stage/aims | Disuse 1 day to 12 weeks | Return to train 3 days to 10 weeks | Train to compete 2 to 10 weeks | Competition |
| Physical | Minimise muscle atrophy | Retrain muscle Optimise physique | Enhance adaptation to training | Train for competition intensity |
| Fitness | Minimise loss of aerobic fitness | Re-develop aerobic fitness | Retrain aerobic/ anaerobic capacity | |
| Nutrition | Energy availability: 146–188 kJ/kg FFM Protein: >2 g/kg BM/ day HBV protein sources high in leucine (>3 g) (every 2–3 hrs) Supplements: Fish oils: 4 g/day, HMB: 3 g/day. |
Energy availability: 188 kJ/kg FFM Protein: 1.4–2 g/kg BM/day HBV protein sources high in leucine (>3 g) (every 2–3 hrs) CHO: to meet training requirement 3–8 g/kg BM Supplements: creatine (load 20 g/ day x 5 days then 5 g/day for return to train) |
Energy availability: 146–188 kJ/kg FFM Protein: 1.8–2.4 g/kg BM/day CHO: vary CHO availability Supplements: to increase work completed/ physiological adaptation |
As per traditional sports nutrition guidelines |
Notes: FFM: fat-free mass, BM: body mass, HBV: high biological value, HMB: b-Hydroxy-b-methylbutyrate, CHO: carbohydrate.
THE ROLE OF SUPPLEMENTATION IN REHABILITATION
While whole foods provide an opportunity for the athlete to meet multiple goals at once and should always be the first choice, supplements may further assist by filling in any gaps within the diet and/or providing concentrated or convenient sources of specific nutrients that may be of benefit. A supplement such as whey protein isolate (WPI) may provide a convenient low-energy (kJ) source of protein during a low-energy requirement period like disuse. Alternatively, other supplements, such as high-strength fish oils, may provide a convenient, and relatively low-cost, option to obtain the large amounts of omega-3 fatty acids needed to attenuate anabolic resistance or inflammation. Finally, conditionally essential amino acids such as arginine have been shown to aid in wound healing (Stechmiller et al. 2005) while more recently there is promising evidence that amino acids abundant in collagen-containing tissues (including bone, tendons and ligaments) may play a role in the regeneration and repair of these tissues (Baar 2017). However, the source and quality of any supplement should be carefully considered with athletes; a recent study in New Zealand found 69 per cent of 32 omega-3 fish oils tested contained less than two-thirds of the amount of omega-3 stated on the label (Albert et al. 2015). Additionally, the risk of contamination with the use of supplements should always be considered by athletes governed by the WADA code (refer to Chapter 12). Therefore, supplementation should be only used as a supportive dietary option and, in most instances, the purposeful use of whole foods and fluids can meet the nutrition requirements of injury rehabilitation.
Whey protein isolate
A by-product of cheese production, which contains a high percentage of pure protein and is virtually lactose-free, carbohydrate-free, fat-free and cholesterol-free.
Arginine
A conditionally essential amino acid that has been shown to have benefits in wound healing.
SUMMARY AND KEY MESSAGES
After reading this chapter, you should understand that strategic and targeted nutrition has the potential to support the rehabilitation process of the injured athlete. This occurs mainly by minimising wasting of essential tissue during disuse and fast-tracking the retraining of injured tissue back to pre-injury levels.
Key messages
• Injuries range from moderate to severe and are related to the characteristics of the sport, with both immediate and potentially long-term consequences for athletes.
• It is important to consider the different phases of the injury/rehabilitation process, from prevention through to ‘return to play’, when considering nutrition interventions.
• It is important to achieve a balance between consuming a sufficient amount of energy to support the body in the healing and regeneration process, and preventing unwanted increases in fat mass.
• The purposeful timing of macro- and micronutrients can significantly influence the adaptations achieved during the rehabilitation process.
• Supplements may be warranted in some circumstances; however, meeting nutrient goals should be achieved through the intake of whole foods where possible.
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