Inflammation and Its Relationship to Exercise and Muscle.
Inflammation results from the ways in which the body reacts to certain kinds of real or perceived threats – like injury, infection or allergens. It can be obvious, like the swelling, pain and redness of a sprained ankle, or it can be unnoticed, like the moderately-raised levels of inflammation that occur within the cells of most people who are inactive and consume a poor diet. Of course, it can also be the damage that is intentionally induced by heavy, prolonged or unaccustomed exercise. This is the form of inflammation we’ll be discussing here.
In and amongst all of this controversy, one thing we know is that when you lift weights, if you go heavy or do it with enough intensity, you cause damage and/or disruption to your muscles – specifically, you damage myofibrils (which are the long, cylindrical structures that make up muscle fibres) and the sarcolemma (which are the membranes that cover the myofibrils). With severe damage, this can result in accumulation of calcium and muscle breakdown products, which signals events that lead to more muscle breakdown, then, subsequently, to repair. This, in turn, causes some degree of inflammatory response. However, the degree of this response and how important it is as a stimulator of muscle growth is hotly debated between scientists and this is the reason why: 1) you hear so many conflicting messages around inflammation; and 2) why it took me over 25 hours to brush up on the arguments on both sides of this debate.
All of this is further complicated by the fact that, in the fitness industry, some coaches, trainers and other gurus recommend minimising inflammation at all costs, while others talk of promoting inflammation as an important stimulus to instigate enhanced muscle growth. There are even supplements and diets specifically designed to both minimise and amplify the inflammatory response to exercise and even some evidence that both may have benefits… So what the heck is going on here?!?!
It’s obvious that this is not a black and white issue, so here’s what I’ve come to think is the best way to look at it.
Primarily, we must consider the “severity” of the inflammatory response and secondly, there are the particular inflammatory pathways being stimulated, then there is the inevitable effect of genetics – some people recover really quickly, some very slowly and there’s everyone in between. So let’s put the severity of response in context for guys who lift weights. Firstly, you need to be aware that even doing a single moderate lifting session, using a certain muscle group, will “protect” that muscle from experiencing as much damage the next time you work it – and this protective effect lasts for at least the next six months. This is called the “repeated bout effect” and it is the muscle’s way of remembering damaging events well enough so that it can protect itself from future harm. So if you lift weights regularly, you’ve trained up your muscles to substantially resist the kind of severe damage that evil scientists perpetrate on unsuspecting newbie study subjects. That means that even if you just “trashed” your quads with 30 sets, unless you’ve just taken some time off the gym or it was a much longer, heavier or more intense session than usual, or you are one of the “slow recoverers”, you aren’t likely to experience the highest degree of damage. For the purposes of this article, let’s start with severe muscle damage.
When people who haven’t done any resistance exercise in quite some time (or ever) are put through their paces, using heavy, repeated, “eccentric” (negative or muscle-lengthening) contractions, this not only causes the initial damage to myofibrils and sarcolemma as described above but this damage signals a chain of events that can cause days or more likely weeks of further damage and breakdown of the muscle. Without getting into too much detail, levels of macrophages and the cytokine IL-6 are most dramatically elevated but also the cytokines IL-10, TNF-a and MCP-1, along with leukocytes (white blood cells, especially neutrophils). These, in turn, release hundreds of other factors.
Macrophages initially break down the damaged muscle but then tidy things up and ultimately improve the muscle-healing process. Others, like leukocytes, may cause further unnecessary damage and do not improve the healing process at all, acting more in a way that is consistent with an immune response to a bacteria or virus than to muscle damage. As is the case with macrophages, without MCP-1 and TNF-a, muscles seem to be unable to regenerate adequately and they might actually get smaller and not bigger following resistance exercise. However, if the levels of MCP-1 and TNF-a become excessive, then this also impairs growth and repair.
However, as I said, this “worst case scenario” of severe muscle damage isn’t likely to happen in response to your next workout, even if you lift heavy and intensely, but the reason I mention it is that many recommendations to increase or reduce inflammation are based on studies that caused this extent of damage – either from using untrained humans or causing massive muscular damage to lab animals. So we have to consider the type and degree of damage that is actually occurring from heavy lifting in the real world when we consider the results of all of the research on this topic.
So let’s look at the more typical damage that may occur from a heavy weights session. In the muscle, the trauma that occurs is more what scientists call “disruption” than “damage”. And because concentrations of calcium and debris from damaged muscle is much lower, far fewer leukocytes (which amplify and prolong the damage) are drawn into the area, resulting in more moderate and brief muscle damage and inflammation. You’ll still have all of the other suspects – macrophages, etc – coming to clean up any damage but most guys will be at least 95 percent recovered by day four. To be precise, data compiled by Australian and Scandinavian scientists shows that almost 50 percent of guys recover within two days, almost 25 percent are 95 percent recovered by four days (and 100 percent by 7 days) and just under 30 percent take over a week (this was in weight-trained men and recovery was measured by the time it took them to regain their strength in the exercised muscle).

Strategies to Alter Inflammation
OK, now the juicy stuff – there are dozens of ways to try to tip the inflammatory scales in your favour for better performance, muscle growth and recovery, but do any of them work? The following are several of the most popular ways to alter inflammation and each one gives us clues as to whether (and/or in what circumstances) we should try to reduce or increase inflammation.

Arachadonic Acid (ARA)
Gym junkies who read up on nutrition and supplements may have heard of ARA. Back when some people first started challenging the idea that inflammation was bad and started suggesting that it was actually required for muscle repair, it was natural that ARA’s name came up. The oversimplistic theory was that ARA boosts cell-signalling molecules called eicosanoids and these stimulate inflammation. Studies in test tubes and in rodents have shown that ARA may stimulate muscle growth. On the other hand, large amounts can actually decrease muscle growth. In human research, a 2007 placebo-controlled study showed that it may improve power performance but didn’t increase muscle mass. Also, this study showed that ARA may actually reduce inflammation, at least it reduced levels of IL-6 significantly. A very recent paper (also double-blind, placebo-controlled), published about five months ago as I write this, showed increased lean body mass, strength and power – it should be noted though, that the paper was funded by a company which sells an ARA product. This doesn’t mean the results are illegitimate but it should be a consideration.
One important thing to remember with ARA is that when its inflammatory effects are blocked, this can reduce or completely inhibit protein synthesis (muscle building activity). This has been demonstrated with anti-inflammatory painkillers like aspirin and ibuprofen. However, in older people, these drugs have been shown to actually enhance the benefits of weight training and this may be due to the fact that most people experience higher levels of inflammation and poorer control of inflammatory damage as they age.

Cold or Ice Therapy May Impair Gains
You may have seen your favourite sports icon sitting in an ice bath after a heavy training session or competition, usually accompanied by the voice of a sports reporter describing how this treatment enhances recovery. Many world-class coaches insist it does so entirely or to some extent by reducing – you guessed it – inflammation, but is there really evidence that this torturous ritual is helpful? Well, the most recent study, conducted at the University of Queensland showed no changes in any inflammatory markers versus using active recovery (light exercise, designed to increase blood flow in the muscles and assist recovery). Even more importantly, two separate studies have recently looked at groups of subjects who did resistance exercise followed by cold water immersion (one study was 6 weeks and the other was 12 weeks). Both studies showed that the ice water significantly reduced gains in size and strength!
Unfortunately, since these two later, long-term studies didn’t measure inflammation, we don’t know if it was over-suppression of inflammation that reduced strength and muscle gains or some other effect of cold therapy.

Nitric Oxide Boosters
Pre-workouts and other “pump” product ingredients (like beetroot, cocoa, citrulline, arginine, etc.) which boost nitric oxide, seem to both reduce inflammation and muscle damage. They also increase performance. Whether their effects on inflammation are a major part of their effectiveness is not presently known but it’s a reasonably good bet!

Fish & Flax (Omega-3) Oils & Inflammation
While adding fish and flax oil to a typical diet, containing too many unhealthy fats will almost certainly decrease inflammation and improve health, it doesn’t seem to alter the inflammation that occurs after three days of very demanding exercise, according to a 2009 study from Appalachian State University, US. However, while fish oil doesn’t decrease exercise-induced inflammation, it may help increase muscle-building activity – in one study, when high concentration fish oil capsules were given to subjects for eight weeks, the anabolic response to protein intake was boosted significantly.

Dairy Foods & Whey Protein
An increase in dairy foods in the diet was shown in a study in the American Journal of Clinical Nutrition to decrease inflammation and several studies show this same effect with whey protein consumption. Whey protein’s effects on muscle may have little or nothing to do with inflammation but in those with an increased inflammatory load, such as (as suggested above) older people or overweight people or those who train very hard and often, this anti-inflammatory effect may reduce the protein breakdown or accelerate repair of protein in muscle.

Leucine + Essential Amino Acids (EAAs)
Interestingly, one way the amino acid leucine and the other essential amino acids improve body composition and performance may be via inflammation also. In a study using very intense eccentric muscle contractions in rats, those rodents given a high-leucine, EAA mixture had lower levels of IL-6 and other measures of inflammation and they recovered their strength much more quickly than the unsupplemented rats.

In consideration of all of the above, it is clear that if inflammation is turned off or reduced too much, muscle recovery and repair can be seriously interrupted. We know this because studies that knocked out the effects of some of these key players in inflammation have been shown to impair muscle repair and growth. On the other hand, several interventions that reduce inflammation also support muscle gains and repair (like amino acids, dairy, whey protein, flax and arachidonic acid). Moreover, excessive inflammation either means you’ve been training too hard, too often or too long for your recovery ability and that means your muscles don’t recover adequately between workouts and this means you don’t get the benefits of super-compensation (muscles getting a tinybit bigger and/or stronger with each training session), so your progress will stagnate or even regress.
The bottom line, after considering all of the research and potential strategies and supplements is that unless you have reached that point at which you’re not recovering or progressing (or if poor diet or exercise habits may be causing unhealthy inflammation in your body), there is no advantage to trying to reduce inflammation. For athletes and those who train really hard, there may be a benefit to occasional ice baths if they will be competing again in the next few hours or days and products like protein and NO obviously have been proven beneficial so we don’t have to be concerned that they’ll excessively reduce inflammation but going to extreme lengths to increase or decrease inflammation otherwise is probably not useful.