Every workout causes microscopic damage to muscle fibers; the inflammation process repairs this damage during the following recovery period.
The muscle soreness and joint pain you experience after workouts are more than just a nuisance. They're symptoms of post-workout tissue inflammation, which slows recovery, limits fitness gains and even causes overuse injuries.
By better managing post-exercise inflammation, you can recover faster, enhance your training adaptations, perform better in workouts and competitions and possibly avoid injuries.
What is inflammation?
Inflammation is an immune system response to tissue damage. Its purpose is to remove cellular debris from the site of damage and initiate repair. There are three phases of the inflammation response.
First, blood accumulates at the site of damage, which causes the classic symptoms of swelling, heat and stiffness that are associated with inflammation. Next, specialized white blood cells called neutrophils migrate to the injured area and absorb the debris of damaged cells.
Finally, other cells known as macrophages accumulate at the site of damage to complete the clean-up process and stimulate tissue regeneration.
Inflammation is a double-edged sword. On the positive side, when a significant injury occurs, inflammation heals it and also produces symptoms of pain and stiffness that discourage activity during the healing process.
A much milder inflammation response occurs after normal workouts in which we don't suffer any serious injuries. Every workout causes microscopic damage to muscle fibers; the inflammation process repairs this damage during the following recovery period, which begins about two hours after a workout and typically resolves after 48 hours.
In addition to repairing everyday muscle damage from exercise, inflammation promotes training adaptations such as satellite cell proliferation, an essential step in the development of bigger, stronger muscle fibers. Inflammation even makes you more resistant to muscle damage in the future (a phenomenon known as "the repeated bout effect").
Studies have shown that untrained individuals become more resistant to exercise-induced muscle damage after just a single workout. It appears that the inflammation response triggered by the first workout increases the activity of neutrophils in the next workout, protecting the muscle fibers from excessive damage.
There's a negative side to inflammation, however. Ironically, although inflammation repairs tissue damage caused during exercise, it also causes further damage, known as secondary muscle damage, between workouts.
Secondary muscle damage is believed to be caused at least in part by the release of free radicals from active neutrophils. Secondary muscle damage is the main reason you feel sorer the morning after a particularly hard workout or race than you do right afterward, and why you sometimes feel sorest two days after the workout or race. This phenomenon is aptly referred to as delayed-onset muscle soreness (DOMS).
Delayed-onset muscle soreness (DOMS) is a symptom of muscle tissue damage that can seriously compromise the quality of your training while it persists. For example, a recent Spanish university study found that DOMS reduced running economy in a group of trained runners by more than three percent (which is a significant amount, considering the fact that a lifetime of training may only increase running economy by 10 percent).
The loss of efficiency seen in athletes experiencing DOMS stems from changes in their normal movement patterns. These changes also place unaccustomed stress on the joints, increasing injury risk.
In athletes who train hard every day, inflammation may not be entirely resolved and muscle damage may not heal adequately between workouts. If you persist in training too hard and resting too little, you may enter a cycle of persistent tissue trauma and chronic inflammation.
Joint tissues also suffer damage during exercise and undergo a subsequent inflammation response. When joint tissues fail to regenerate fully between workouts, they may become chronically inflamed and/or degenerate to the point of serious injury. Overuse injuries that are all too familiar to, such as runner's knee, develop in this manner.
What can you do to limit post-workout inflammation and its negative effects? The most effective thing you can do is to reduce the amount of muscle damage you experience in the first place during workouts by taking advantage of the repeated bout effect. Thanks to this phenomenon, during any given workout your body always has enough neutrophil protection to handle tissue stress equal to that of your most recent workouts.
Therefore only workouts that are harder than normal cause significant tissue damage and post-workout inflammation. So if you're always careful to increase your training level very slowly, you'll make better progress than if you try to build your fitness in great leaps.
Until recently, this was about all you could do. But a new type of supplement known as HIMF (which stands for hyperimmunized milk factor) is showing great promise as a way to reduce the sort of inflammation runners deal with daily.
Special immune stimulants can be administered to cows, causing them to produce milk containing antibodies with powerful anti-inflammatory properties. These antibodies are present in regular cow's milk in small amounts, but thanks to a series of recent technological advances, it's now possible to isolate and concentrate these anti-inflammatory antibodies in a convenient supplement form: HIMF.
Research suggests that HIMF reduces inflammation by reducing the number of neutrophils that successfully pass through blood vessel walls to the site of tissue damage. An early study showed that HIMF reduced neutrophil migration to a site of inflammation by 75 percent.
Subsequent studies involving osteoarthritis sufferers found that HIMF was effective in reducing joint pain and stiffness, and one study even found HIMF to be 60 percent more effective than glucosamine in restoring joint junction.
A study involving competitive runners didn't look at inflammation directly, but instead investigated the effects of HIMF on factors that one would expect to be positively impacted by reduced post-exercise inflammation: muscle recovery, training progress and race performance. In this double-blind, randomized study, performed by researchers at the University of Puget Sound, runners received either a daily HIMF supplement or a placebo (regular milk) for six months.
On average, the runners receiving the immune milk experienced significantly greater improvements in post-workout recovery time, muscle damage levels, perceived improvement in training, and even 5K-race times than those receiving regular milk. The HIMF-supplemented subjects also experienced a slight decrease in body fat percentage due to muscle weight gain.
Future studies will be needed to investigate the effects of HIMF on post-exercise inflammation in athletes and to establish a link between this effect and the improvements in training quality and race performances observed in the Puget Sound study.
In the meantime, you may consider undertaking your own experiment by trying an HIMF supplement for a few weeks. As yet there are only a couple of HIMF supplements on the market: MicroLactin, which is marketed mainly to arthritis patients, and RX-98, which combines HIMF with a whey protein isolate and is made specifically for athletes.