(It would be great if we, as humans, made decision based purely on logic, but as expert sport psychologist Dr. Peter Jensen PhD points out, it’s not usually the case).
Athletes train hard. They train almost every day, often twice a day, in order to be elite..
Does this mean athletes are constantly in a state of delayed-onset muscle soreness (DOMS) or fighting off excessive inflammation to effectively adapt to training to achieve their goals? Maybe. What about an athlete’s training phase, does that play a role? For example, if an athlete is optimizing for competition versus adapting to get bigger, stronger, or faster?
What about recreational clients?
For many people, the sensation of mild to moderated delayed DOMS that creeps into your muscles 24-48 hours post-training is a sign of a good workout. You feel like you’ve trained and are making progress toward your goal. However, if it persists for more than 48 hours, if it limits your range of motion (ROM) or muscle function is it still helpful?
Exercise-induced muscle damage (EIMD) is a complex and nuanced topic.
A better question is when does exercise-induce muscle damage become so pronounced it requires specific nutrition strategies to mitigate the effects? I interviewed expert Dr. Daniel Owens PhD from Liverpool John Moore’s university to talk about his research in this area and what nutrition solutions you can turn to for evidence-based recovery support.
First, let’s define exercise-induced muscle damage.
What Is Exercise-Induced Muscle Damage?
Exercise-induced muscle damage (EIMD) is characterized by symptoms that come on directly after training and persist for 1-5 days afterwards (although potentially all the way up to 14 days post-training). That’s a pretty wide margin, what happens if you get your training plan or recovery process wrong?
For the athlete, the consequences of EIMD include is a direct effect on functional capacity (e.g. strength, range of motion, etc.), muscle soreness, muscle capacity and sense of force production and limb position.(1,2,3,4) How long and how intense these symptoms are for you depends on the intensity and duration of exercise and how your own individual susceptibility to the damaging stimulus of training.
For the athlete, loss of muscle function and increased muscle soreness likely have the greatest potential to negatively impact performance.
Can targeted nutrition strategies help to offset these effects? Could this allow you to train more frequently or more intensely, thereby increasing the likelihood of achieving your goals? Or could it actually interfere with the recovery process?
It’s a matter of balance; adequate training stress combined with sufficient recovery. Let’s take a deeper-dive into what causes exercise-induced muscle damage.
What Causes EMID?
Training of any type can cause exercise-induced muscle damage (EIMD), however there are a few types of training that may trigger greater muscle damage, such as; resistance training, prolonged or downhill running, and high-intensity interval training.(5,6,7,8)
Muscle damage is amplified during eccentric actions, particularly at longer muscle lengths, with greater forces, and faster angular velocities.(9,10,11) Interestingly, if you perform a training session with more eccentric loading, it may actually reduce the EMID in the subsequent sessions, a phenomenon known as the “rebound effect”.
What are the underlying mechanisms that cause EMID? Let’s review.
#1 Primary Muscle Damage
Experts aren’t exactly sure the principle reason why eccentric training is more damaging to the muscle, however the consensus seems to be the mechanical loading during exercise.(12) Eccentric contractions have a lower motor unit activation compared to isometric and concentric contractions (when force is equal), putting an increased mechanical stress on a smaller number of muscle fibers during eccentric movements, and thus more muscle damage.(13)
#2 Secondary Muscle Damage
After the initial primary damage of training, a secondary effect occurs when calcium moves into cells, as the mitochondria attempt to maintain homeostasis.(14) The resultant inflammatory response is a crucial and natural process that clears away damage tissue, triggers tissue repair, and ultimately adaptation.
#3 Satellite Cell Activation
Muscle fiber recovery and regeneration requires the activation of muscle stem cells called satellite cells. Satellite cells are activated post-training, specifically in response to eccentric compared to concentric contractions.(15) The research highlights that sustained activation of satellite cells provides the muscle with the capacity to adapt more effectively from training.
To sum up, impaired muscle function, increased muscle soreness, elevated inflammatory levels and activation of satellite cells all play a role in exercise-induced muscle damage.
What does all this mean for you the athlete?
Nutritional strategies to target these areas - when used in the right context – may improve recovery from exercise-induced muscle damage. Let’s review five evidence-based nutrition strategies.
Dietary Solutions for EIMD
Now you’ve understood the mechanisms underlying exercise-induced muscle damage (EIMD), you can better appreciate what nutritional interventions influence those mechanisms in order to exert a desired effect.
There is a lot of nuance when it comes to application.
You don’t want to limit or buffer the exercise-induced stress and subsequent beneficial adaptations to training. The nutritional strategies we’ll discuss impact inflammation and oxidative stress – known to be important stimuli for adaptation - so it’s important to consider why you’re using them (i.e. to cope with increased training volume and/or intensity) and when you’re using them (i.e. adaptation versus optimization phase).
The following are five potential evidence-based nutritional strategies.
Protein is crucial to muscle protein synthesis and adaptation to resistance and endurance exercise.(16) Experts can’t say for sure whether protein around intense or damaging exercise can limit EIMD, but recent evidence suggests it can improve markers of muscle damage and accelerate recovery of force.(17,18) Aim for a protein intake of 0.2-0.5g/kg/meal around exercise, with bigger athletes trending toward the upper end of the range.
#2 Tart Cherry Juice
Dietary polyphenols are most commonly found in the diet via fruit, vegetable, tea and coffee consumption. Polyphenols have shown to exert significant antioxidant and anti-inflammatory effects, possessing the ability to attenuate cyclo-oxygenase (COX) 1 and 2 output to a similar degree compared to common, over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs).(19,20)
In particular, tart cherry juice stands out from the pack when it comes to recovery.
Research in resistance training using heavy eccentric bicep curls combined with two servings of tart cherry juice per day found an accelerated rate of recovery and reduced muscles soreness.(21)
A key benefit to using a “food first” approach to performance nutrition is that it’s unlikely to interfere with the primary muscle damage response from exercise and thus not limit positive adaptation to training (compared to supra-physiological doses in supplements). Where functional foods like cherry juice can exert its effect is during the secondary phase, when inflammation and oxidative stress ramp up post-training.
Omega-3 polyunsaturated fats, specifically eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA), are important nutrients that exert anti-inflammatory effects. Omega-3 fats like EPA and DHA are found in highest abundance in cold, deep-water fatty fish (e.g. salmon, mackerel, anchovies, sardines, herring, etc.), seafood (e.g. oysters, mussels, etc.), grass-fed beef and nuts like macadamia and walnuts
Numerous studies have shown beneficial effects of omega-3 on inflammation, oxidative stress, and muscle function after intense exercise.(22,23,24,25)
Interestingly, there appears to be a “loading phase” of approximately two weeks to see changes in muscle omega-3 composition. A recent study found a highly effective loading protocol to be 5g/day dose of fish oil capsules (providing 3,500mg EPA and 900mg DHA), however this is much higher than the current recommendations.(26) Typically, a dose of 1,000-1,500mg (combined EPA/DHA) is suggested in athletes, however more research is needed in this area to confirm an ideal dose.
#4 Vitamin D
Vitamin D isn’t really a vitamin. In truth, it’s a seco-steroid hormone acquired by the body through exposure to the sun (e.g. ultraviolet B radiation or UVB). Sedentary lifestyles in the general population and athletes training indoors (or even outdoors in sun-shy athletes wearing skin covering apparel) has led to a large of number of athletes and active people being diagnose with deficient (< 30 nmol/L 25[OH]D) or insufficient levels of vitamin D.
In the last decade, new technology has allowed for discoveries of the important effects of vitamin D on muscle function and performance.
Vitamin D is a potent regulator of the immune system and has shown to exert potentially important effects on athletic recovery; anti-inflammatory response post-exercise was found to correlate with the individual’s vitamin D levels, runners with low vitamin D exhibited increase inflammatory responses post-exercise, and athletes performing eccentric-concentric jumps on a plyo-press displayed faster recovery at higher vitamin D status.(27,28)
Creatine is keystone supplement in many athlete’s nutritional arsenal. However, many are unaware of the impacts of creatine on recovery. Creatine has shown beneficial effects on satellite cell number and muscle function post-training.(29)
The Bottom Line
Exercise-induced muscle damage is an important and natural phenomenon that triggers the positive and beneficial adaptations to exercise. In the general population, training stimulus and volume is unlikely to require additional recovery support beyond the nutrition fundamentals of adequate protein, omega-3 and vitamin D intake are likely all you need to support your training goals.
In athletes, the stakes are much higher. Greater training volume and intensity, as well as two-a-day (sometimes three-a-day training in MMA athletes!) increases the need for the application of functional food strategies to support quicker recovery.
As always, think about the type, timing, and total amount of the supplement, functional food, or nutritional strategy you’re implementing with clients and athletes.
(Now get back to your training!)
Dr. Marc Bubbs ND, CISSN, CSCS
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In the Paleolithic or ‘hunter gatherer’ era, from 2.6 million years ago until the agricultural revolution 10,000 years ago, our ancestors woke up with the rising sun in the morning and rested for a good nights sleep not long after sundown. Scientists estimate that our Paleolithic ancestors averaged about 10 hours of sleep per night. Of course the absence of an external light source, television sets, and laptops made it a little easier to get to bed so early, but the benefits are deeply engrained in our DNA.
Your circadian rhythms are based on the light and dark cycles of the day and have a profound effect on your bodyweight, cardiovascular health, fertility, and well-being. Melatonin, your body’s sleep hormone, is secreted in the evening about 3 hours after your last meal. It makes you feel tired, drowsy, and prepares you for deep rejuvenating sleep.
In winter, Paleolithic people slept longer hours – approximately 10-12hrs per night – as the days got shorter and darker. Your immune and hormonal functions are linked to these evolutionary circadian rhythms of light and dark, and understanding how this effects you will help you improve your energy levels, build muscle, burn fat, and upgrade your overall health.
For example, daylight increases your dopamine and cortisol output, getting you out of bed and ready for the day ahead. When was the last time you felt energized in the morning? How many cups of coffee do you go through to get yourself going in the morning? Do you need your alarm clock to wake up or do you wake up naturally?
Your natural hormonal patterns shift throughout the day and by nightfall your cortisol and dopamine levels should be at their lowest, allowing melatonin production to kick in and stimulate your repair and rejuvenation hormone... growth hormone. Growth hormone is essential for rebuilding your body while you sleep, helping to build lean muscle, burn fat and keep your immune system strong. (Your body is hard at work while you rest!)
So what’s the problem with our 21st century sleep patterns?
Two generations ago, our grandparents average about 9-10 hours sleep per night, not very far off our Paleolithic ancestors. Today, the average North American gets between 6-7.5 hours of sleep, about an hour or two less than the recommended 8 to 8.5 hours sleep per night. Over the course of a year, this would amount to approximately a 500-hour ‘sleep debt’!
Over-consuming coffee can add to the problem. How do you know if you are over-doing the stimulants?
You’ve been abusing your coffee intake if you don't feel the same ‘kick’ from your morning cup of joe, or if stopping your intake results in headaches, irritability, or intense fatigue. Coffee triggers the production of adrenaline from the adrenal glands and stimulates our sympathetic – ‘fight or flight’ – nervous system. While this is okay in moderation, chronically relying on this form of energy is like revving the RPM’s on your car constantly into the red zone. Before too long, you'll burn out your engine!
So what can you do to start cutting into your sleep debt?
Let’s start in the bedroom. The key to sleep is ensuring you have total darkness in your bedroom. Make sure to remove all light sources (think red lights from the alarm clocks), cell phones on the bedside table, and nearby laptops from the vicinity of your head. All of these stimulate the nervous system and prevent deep sleep. Next, turn off the television or shut off your laptop at least an hour before bed to allow your body to unwind. All of these stimulants activate the nervous system and prevent deep sleep. Finally, get to bed before midnight to increase your number of sleep hours per night. In Tradtional Chinese Medicine (TCM), every hour of sleep before midnight counts as DOUBLE, because they are so valuable for restoring health and wellness.
Make time to 'schedule' in more sleep... it will pay off with better energy, productivity, and performance at work and in the gym!
Dr Marc Bubbs ND, CISSN, CSCS
Check out more articles in the SLEEP SERIES...
- 7 (Evidence-Based) Reasons To Nap More
- Ancestral Clues To Better Sleep
- After Hours Emails Ruining Your Sleep?
- How Important Is Sleep? Just Ask The World Series Champs!
- Sabanayagam C, Shankar A. Sleep duration and cardiovascular disease: results from the National Health Interview Survey. Sleep.2010 Aug;33(8):1037-42.
- Alvarez GG, Ayas NT. The impact of daily sleep duration on health: a review of the literature. Prog Cardiovasc Nurs. 2004 Spring;19(2):56-9.
- Ayas NT, White DP, et al. A prospective study of self-reported sleep duration and incident diabetes in women. Diabetes Care. 2003 Feb;26(2):380-4.
- Chaput JP, Després JP, Bouchard C, Tremblay A. Association of sleep duration with type 2 diabetes and impaired glucose tolerance. Diabetologia. 2007 Nov;50(11):2298-304. Epub 2007 Aug 24.
- Vgontzas AN, Bixler EO, et al. Chronic insomnia is associated with nyctohemeral activation of the hypothalamic-pituitary-adrenal axis: clinical implications. J Clin Endocrinol Metab. 2001 Aug;86(8):3787-94.
- Kobayashi D, Takahashi O, , et al. Association between weight gain, obesity, and sleep duration: a large-scale 3-year cohort study. Sleep Breath. 2011 Sep 3. [Epub ahead of print]