This is a long form article where we provide a deep dive into nutrition and it’s impact on injuries. This piece was originally part of  course within Kevin’s master’s degree program in Nutrition from Indiana University of Pennsylvania. 

Injury in Sport – Nutrition Considerations

Injury is almost inevitable in athlete level individuals and can cause athletes to reduce training load or withdraw from training and competition.1 With insufficient training stimulus, a detraining effect occurs, which can cause a partial to complete loss of the metabolic and physiological adaptations to training.1 The immune system plays an important part in the repair of tissue after injury. Therefore, if the immune system is compromised during periods of high-intensity training or when there is insufficient food or fluid intake, it can increase the susceptibility for infection and slow the rate of healing and recovery from injury.1 

Injuries in sports can be acute or chronic in nature and can affect muscle tissue, bone, or ligaments, typically lasting weeks to several months.2 Moreover, injuries range from very minor scrapes and bumps to more severe harm requiring prolonged inactivity and/or limb immobilization.3 Severity of sports injuries can be described on the basis of six criteria: the nature of the sports injury, the duration and nature of treatment, sporting time lost, working time lost, permanent damage and monetary costs.4

Chronic and Acute Injuries

Chronic injuries are a results of cumulative trauma and repetitive use and stress, lasting beyond 6 months.2 Moreover, chronic injuries are more prevalent in low-contact sports that involve extended training period, repetitive motions, and frequent use of specific body parts such as running, swimming, and cycling.2 Subsequently, sports that require throwing and jumping, in addition to sports in which training intensity and load increase over a short period of time are also susceptible to chronic injury.2 Furthermore, chronic injuries include bursitis, inflammation, loose cartilage, stress fractures, and tendinitis.2 Acute injuries tend to be more prevalent in fast-paced and/or contact sports, such as football.2 Moreover, acute injuries include dislocation, fracture, wounds, sprain or strains, and contusions.2 

Overall, nutrition with regards to injuries in sports is essential as insufficient macronutrient and energy intake can negatively affect the recovery process.2 Therefore, it is important to consider macronutrient, micronutrient, and overall energy intake when recovering from an injury. Moreover, there is no standardization in definitions of a sport injury applied in research studies. At present, rather than sports injury, the comprehensive term sports-related injury is used.4 This can include any injury that affects the individuals’ ability to engage into sports activities regardless of where this injury was sustained.4 Therefore, it also incorporates injuries sustained during non-sports activities.4

The Science Behind Injuries

Although not clearly established, most exercise-induced injuries cause an athlete to stop training or involve full or partial immobility of a limb and go through two main physiological stages of recovery.¹ ² The first stage involves tissue repair, inactivity, and muscle atrophy.¹ ² The repair process begins almost immediately after injury and can continue for days to weeks depending on its severity. An inflammatory response is the initial physiological response to injury, which is an essential component of the healing process and can last for a few hours to several days.1 Moreover, because inflammation is an important step in the healing process, chronic intake of strong anti-inflammatory medications that suppress or eliminate the inflammatory response during the recovery phase may not be ideal for optimal recovery. 

Exercise-induced injuries involve limbs that require immobilization and a reduction of overall physical activity. Probably the most prominent metabolic contributor to muscle loss with disuse is the resistance of muscle to anabolic stimulation.3 The response of MPS to amino acids and exercise is reduced following a period of disuse and is termed “anabolic resistance”.3 It is clear that MPS does not respond as well to protein ingestion after disuse compared to when the muscle is active.3 Therefore, the rate between muscle protein synthesis (MPS) and muscle protein breakdown changes, which results in a reduction in muscle mass, strength, and functional capacity.1 Muscle is lost over any given period of time when intervals of negative net muscle protein balance (NBAL) are greater than intervals of positive NBAL.3

Moreover, recent evidence suggests that simply reducing activity for 14 days leads to anabolic resistance in muscle.3 Therefore, even if an injury does not result in full immobility of a limb, reduced activity as a result of the injury could lead to metabolic impairments and loss of muscle size and function.3 Bone, tendons, and ligaments are also negatively affected by immobilization and reduced activity.1 Decreased collagen synthesis in tendons from immobilization results in impairment in tendon mechanical properties. Additionally, nearly all aspects of mitochondrial metabolism and function are impaired in muscle that is immobilized and inactive.1

Therefore, oxidative capacity, enzyme and signaling pathways involved in mitochondrial biogenesis are depressed or reduced. Furthermore, simply reducing activity of muscle for 14 days may lead to decreased insulin sensitivity of muscle.3

 How to Manage Your Injury

 The impact of injury can take many different forms in athletes. Serious injury in athletes can lead to partial or total immobilization of a specific part of the body.¹ The immobilization of a limb can lead to atrophy and a reduction in strength and function in the affected skeletal muscle.1,3 Injury can also be so serious that it leads to cessation of all training.  More than half of injuries sustained by elite athletes are severe and can lead to cessation of training for up to 74 days.1 During training cessation, athletes can see an increase in muscle atrophy due to physical inactivity.1,3

Both cessation of training and total/partial immobilization are often treated with some combination of rest, ice, massage, heat, limb casting, electrical stimulation, acupuncture, and/or manual therapy. Rest, ice, and limb casting can be used to help manage inflammation in the first stage of injury recovery.  Electrical stimulation can be utilized as an adjunct therapy to counteract muscle atrophy due to disuse.1 It is used to stimulate muscle protein synthesis (MPS) which can also be done through dietary protein intake. Sufficient dietary protein intake can be used in conjunction with electrical stimulation or by itself in managing injury recovery. Adequate protein intake can help with some of the negative effects of inactivity such as muscle loss and decreased collagen synthesis.1 

In a non-injured athlete, protein intake adequately stimulates MPS in the body. However, in an injured individual, protein intake does not have the same stimulatory effect.¹  This can be partially attributed to anabolic resistance which is important to note because it gives the body a reduced response of MPS to nutritional anabolic stimuli (i.e. protein).¹  Anabolic resistance decreases the ability of the body to respond to amino acids and protein intake which can lead directly to furthered muscle atrophy, loss of muscle strength/function, and decreased athletic ability.¹ So, it is suggested to adjust protein and amino acid (specifically leucine) intake during recovery from an injury.¹  If the injury is severe enough, energy requirements in general can be up to 20% higher than normal.¹ Some managing may also occur in retraining the atrophied muscles after recovery.

Lastly, Omega-3 fatty acids (n-3 FA) are currently being studied to help manage injury conditions. Fish oil specifically can be used to depress inflammatory responses for athletes with excessive and chronic inflammation.1,5 In addition, there are limited animal studies to suggest that n-3 FA supplementation can reduce the effects of muscle atrophy.  These studies also reveal that n-3 FA supplementation can prevent and treat brain injuries incurred by concussions.  While these sound like positive outcomes, athletes should still be careful of the long term effects of n-3 FA supplementation and they should look for more evidence based studies before they proceed.1,5  For an injured athlete not experiencing either of these conditions, it is recommended that they do not use n-3 FA supplementation.

Evidence-based sports nutrition guidelines for the management of the condition

Nutritional support for stage one, which includes tissue repair, inactivity, and atrophy, is similar to nutritional support for stage two, which is rehabilitation. Both however may be influenced by nutrition choices of the injured client.2 While both are similar there are minor modifications depending on the location and severity of the injury. There are multiple nutritional interventions for stage one and the first one consists of the effect of total protein intake on muscle protein synthesis. Inadequate total dietary protein consumption impedes wound healing and is also required for the synthesis of collagen and other proteins that are involved in the repair process.

The intake of protein stimulates muscle protein synthesis at rest and during exercise, resulting in a positive protein balance. The rate of MPS is suppressed in injured athletes because of reduced sensitivity of inactivity muscle to hyperaminoacidaemia.1 This suggests greater amounts of protein may be needed to stimulate maximal rates of MPS after injury. During immobilization it may be crucial to adjust protein and amino acid intake throughout the day to maximize consumption.

The primary amino acid responsible for activating the start of muscle protein synthesis is leucine. In animal studies leucine ingestion ameliorated muscle loss during periods of immobilization. High doses of essential amino acids in human studies showed evidence of reduced loss of lean body mass in weight-bearing limbs in health adult males during 28 days of bed rest and during immobilization in health adults.1 Damage compromises collagen synthesis, which is the primary protein in tendon, and impairs function.

The rate of collagen synthesis in muscle and tendon does not seem to be nutritionally managed which leads to the conclusion that amino acids have little impact on recovery and healing. Arginine, a precursor of the amino acid proline, has been found to enhance wound collagen deposition.1 Bone collagen synthesis however does respond to increased protein intakes. Studies with elderly patients consuming a protein supplement showed improvements after hip fracture surgery.1 To conclude the efficiency of increased protein and amino acid consumption during recovery would need further research.

Protein intake every three hours each day may result in increased stimulation of muscle protein synthesis. This structured timing may hold similar effects in athletes with muscle atrophy from disuse or injury. Ingestion of high biological value protein, such as whey protein supplements, at 0.3 g/kg/BM shortly after exercise promotes maximal protein synthesis.1 Low protein ingestion prior to an injury negatively affects recovery time. A sudden decrease in protein intake right before an injury would have the same effect. A prolonged decrease would result in a large negative nitrogen balance which can promote even higher muscle loss.

A Counterintuitive approach – Increase Calories

To maximize recovery rates an athlete must pay attention to their energy balance during recovery. Sadly, the first thought of most injured athletes is to reduce energy intake to avoid weight gain. By doing this there is an increased risk of a slower recovery from the injury. Energy requirements vary at different stages of recovery and are determined by the severity of the injury. When an injury is severe it is possible for energy intake to be up to 20% higher than usual requirements.1 Depending on the severity of the injury and the available mobility, energy intake may not need to be reduced. A negative energy balance during recovery will inhibit MPS.  Decreased muscle protein synthesis is the main contributor to muscle loss. To avoid the fear of weight gain during recovery it is recommended to assess energy intake, body mass and body composition during immobilization.

Supplements

Omega-3s are universally known for their anti-inflammatory properties, however other findings suggest omega-3 supplementation can reduce muscle soreness and lessen oxidative damage to muscles.5The anti-inflammatory and immune modulatory properties of omega-3 fatty acids are used therapeutically as supplements in high doses. Fish oil supplements have the ability to decrease the inflammatory response for injured athletes in recovery. People with ongoing inflammation such as chronic arthritis, who consume fish oil supplements have seen a positive impact on their condition.1  However therapeutic dosages given to athletes may be counterproductive to the recovery process, although there is no direct evidence of this in human studies. Rat studies have concluded evidence of impaired wound healing with omega-3 supplementation.1 Additionally, animal studies show evidence that fish oil supplements may ameliorate muscle atrophy during immobilization. While there are multiple animal studies, any human based study suggests that omega-3 supplements may enhance the metabolic effects of amino acid and insulin infusion into the muscle.

Varied recommendations for a dosage of the inflammatory-limiting effect of n-3 FA include 1-2g/d to 4g/d.1 The most useful recommendation for enhancing anti-inflammatory effects include a low ratio between omega 6 and omega 3 which would further mean consuming less omega-6 and consuming more omega-3. In conclusion, unless the injury causes an excessive inflammatory response there is little reason to use omega-3 fatty acid supplements.

When healing from fractures to optimize bone formation, it is important to consume a sufficient intake of calcium and vitamin D. During malnutrition, wound healing is impaired and is linked to sub-optimal micronutrient status of zinc, vitamin C, and vitamin A. For example, vitamin C is associated with hydroxyproline synthesis, which is needed for collagen formation and is a crucial component of wound healing and repair of damage to bone, ligaments, and tendon injuries.1 No clear evidence has been produced for the use of micronutrients supplements or higher micronutrient requirements as a mean in accelerating recovery.

In muscular dystrophy cases creatine is used as a therapeutic tool to decrease the rate of muscle loss associated with immobilization. The use of creatine has been investigated for its potential effect on counter measures to muscle loss during immobilization due to its success as a sports supplement.1 In conclusion more research is needed to determine the effect of creatine supplementation on muscle loss in various muscle groups.

The last nutritional intervention regarding stage one is the effect of alcohol intake on recovery. Ethanol ingestion impairs wound healing which is mediated by decreasing the inflammatory response. Excessive amounts of ethanol also impair muscle protein synthesis and increase muscle loss which have been seen in multiple animal studies.1 With the presented effects, it is recommended to limit or avoid alcohol during immobilization and recovery from an injury.

Overall, the primary nutritional goal following injury-induced immobility is to support muscle growth and increased strength with retraining and rehabilitation.1 Rehabilitation is also the second stage for nutritional support. Nutritional management is much like exercise management after an injury both desiring and increase in muscle mass. The most crucial nutritional intervention is to meet energy and protein requirements.1 The recommendations for protein intake during stage one are the same during stage two. During rehabilitation, limiting carbohydrates is not recommended because low consumption during and after exercise impairs muscle protein synthesis and net muscle protein balance when muscle glycogen levels are low.1 During rehabilitation both timing and total of carbohydrates may be extremely important.

Creatine supplementation may be optimal during the rehabilitation phase, but limited research as said otherwise and is still undecided. In conclusion it is important to recognize which stage of the healing process an injured client may be in. Any recommendations or management techniques should be individual to the client.4 During the recovery process supplementation is not always needed in certain situations. Dietary variety should be emphasized to obtain the necessary nutrients for recovery.4

Protein Intake During the Injury Phase

When an athlete becomes injured, it is more than likely that their overall physical activity levels decrease. The basis of a nutritional strategy for an injured exerciser should be a well-balanced diet based on a diet consisting of whole foods from nature that are minimally processed. Treating inflammatory responses in relation to injury is important. Some supplements to reduce inflammation are omega-3 fatty acids, vitamins, and phytonutrients. For those athletes that are concerned with recovering back to the training levels they were before injury, athletes need to appropriately adjust their energy intakes. 

There are subtle things during injury that may actually increase energy expenditure 15-50%; and the duration of the increase depends on the severity of the injury. Ambulation on crutches can cost 2-3 more times the energy than regular ambulation. Total energy expenditure may not decrease as much as expected unless the athlete fully restricts ambulation during injury. If an athlete restricts energy intake too much, recovery time will be slowed due to impaired wound healing and exacerbated muscle loss.

Protein should be consumed during injury because of its positive effects on muscle adaptations and most important for injuries involving immobilization and muscle loss. Intake should not decrease even in the face of injury and reduced energy intakes. Muscle protein synthesis is maximized with the ingestion of ~20-25g or 0.25-0.30 g/kg BM in one dose in both resting and contracting muscle. However, it is likely that the amount of protein in each dose necessary to maximally stimulate MPS in immobilized muscle due to injury, will be increased. Higher protein intakes of ~2-2.5 g/kg BM may be warranted. Also, essential amino acids found in protein have been shown to be effective for amelioration of muscle loss with inactivity.3 

There is also promising evidence that the efficacy of other nutrients such as leucine, curcumin, and n-3FA may be helpful during injury recovery but they must be warranted before recommendations for wholesale use of these nutrients by injured athletes are made. Deficiencies, particularly energy, protein, and micronutrients must be avoided for energy balance is crucial.3 Micronutrients such as calcium and vitamin require sufficient intakes during healing from fractures is important to optimize bone formation. 

Wound Healing

Wound healing can impair natural nutrients such as zinc, vitamin C, and vitamin A, so supplementation may be useful. Athletes benefit from a meal plan with sufficient calories and intake of macronutrients and micronutrients (particularly iron, zinc, and vitamins A, D, E, B6, B12 and folate) to enhance immune system function, reduce risk of illness, and promote recovery after illness or injury. Benefits of ingesting foods and supplements rich in polyphenols (flavonoids) and probiotics to treat ERT and GIT infection are emerging. Energy requirements at the rehabilitation stage may be higher than expected, especially for an athlete on crutches. Creatine (monohydrate) supplementation may help limit muscle atrophy and subsequent muscle hypertrophy during rehabilitation.1 

Fluid Intake

Fluid intake also plays a major role in the tissue repair of recovery. Recommendations for total water intake from food and beverage are for males: 2.4L/day for ages 9-13, 3.3 L/day for ages 14-18, and 3.7 L/day for ages 19 and older. For females the recommended intakes are 2.1L/day for ages 9-13, 2.3L/day for ages 14-18, and 2.7L/day for ages 19 and older. Inflammation can limit the flow of oxygen to the healing tissue resulting in the formation of dead cells. Adequate fluid intakes are needed for dead cell removal and the addition of nutrients needed for recovery.2. If an athlete is experiencing a concussion, it is found that omega-3’s have a role in maintenance of neurons. Studies mostly in animals, suggest that omega-3 supplementation may be effective in both the prevention and treatment of traumatic brain injury resulting from concussions. Omega-3 has been shown to improve performance in strength, power, endurance, and recovery.5

Are you currently recovering from a sports injury in Waterford? Do you need help and guidance so that you can build strength and get back to being at your best? Come train at Motiv8 Fitness. We specialise in athlete and team based training and guarantee to get you the results you deserve. Contact us to get started or for more information.

References: 

1. Burke, L, Deakin, V. Clinical Sports Nutrition. 5th Edition. Australia: McGraw Hill Education; 2015. 

2. Robertello N. Today’s Dietician . Nutrition and Sports Injuries. January 2020.

3. Tipton, K.D. Nutritional support for injuries requiring reduced activity. Sports Science Exchange; 2017: 28(169), 1-6. Retrieved From: https://d2l.iup.edu/d2l/le/content/2750096/viewContent/21236057/View

4. Baarveld F, Visser CA, Kollen BJ, Backx FJ. Sports-related injuries in primary health care. Fam Pract. 2011;28(1):29–33. doi:10.1093/fampra/cmq075

5. Webb D. Omega-3s for Sports Performance. Today’s Dietitian. 2020;22.