Inflammation not only signals that your body is on the mend from a serious injury, but it's also the means by which your muscles get stronger in response to intense training. However, if you train too hard, too often, post-exercise inflammation may become chronic -- compromising your recovery from workouts, limiting your body's adaptations to training and increasing the likelihood of over-use injuries.
All of this reminds us that preparing for peak performance is about training smart -- pushing yourself to the edge while being careful not to fall off it. Understanding how to manage post-exercise inflammation can help you pull off this balancing act.
A Double-Edged Sword
Inflammation is an immune system response to tissue damage. When an injury occurs, inflammation removes cellular debris from the site of damage and initiates repair. There are three phases of the inflammation response. First, blood accumulates at the site of damage, causing the classic symptoms of swelling, heat and stiffness.
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 to complete the clean-up process and stimulate tissue regeneration.
Inflammation cuts both ways, though. On the positive side, it heals an injury 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 happens typically between two to 48 hours after a workout.
In addition to repairing muscle damage from exercise, inflammation promotes training adaptations such as 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 (known as "the repeated bout effect").
Studies show 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.
Although inflammation repairs tissue damaged during exercise -- and here's the negative side -- it also results in further damage between workouts. It's believed that in the process of healing injured tissue, active neutrophils also release cell-damaging free radicals that produce secondary muscle damage. This is the source of delayed-onset muscle soreness (DOMS), when you feel sorer the morning after a hard workout than you do immediately afterward, and why you sometimes feel sorest two days after the workout or race.
DOMS can seriously compromise the quality of your training. For example, a recent Spanish university study found that DOMS reduced running efficiency in a group of runners by more than three percent (a significant amount considering that a lifetime of training may only increase running efficiency by 10 percent), primarily because they changed their form in an effort to reduce DOMS. These changes also placed unaccustomed stress on the joints, increasing injury risk.
When joint tissues suffer damage during exercise, they also undergo a subsequent inflammation response. If these 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 athletes, such as runner's knee, develop in this manner.
If you train hard every day, the muscle and joint damage you experience may not heal adequately between workouts and the inflammation response may not fully resolve. If you keep on training too hard and resting too little, you may enter a cycle of persistent tissue trauma and chronic inflammation.
Some believe that chronic inflammation is the root cause of overtraining syndrome -- a serious condition characterized by persistent fatigue, poor performance, loss of motivation and other symptoms that affect some athletes.
Tame the Flame
You can't eliminate post-workout inflammation. Even if you could, it would be a bad idea because it helps your muscles adapt to training, as long as it doesn't get out of control. To keep inflammation under control, do the following:
Obey the Hard/Easy Rule
Hard workouts cause your muscles to adapt in ways that make them more resistant to exercise-induced inflammation. But they need a chance to adapt. If you train hard every workout with no recovery or rest days in between, your muscles won't get that chance. Follow a training schedule that alternates intense days with light or rest days so your body can respond to the stress of those harder workouts.
Prepare Your Muscles
Research has shown that athletes can increase their muscles' resistance to exercise-induced damage and inflammation by engaging in small amounts of high-intensity eccentric (pronounced ee-centric) muscle work.
An eccentric muscle contraction occurs when a muscle resists its own lengthening, like in the lowering phase of a biceps curl. Eccentric or lengthening contractions cause the most muscle damage, but in small doses they also do the most to toughen muscles against future damage.
Before you begin any period of intense training, inoculate your muscles against damage and inflammation by doing strength workouts emphasizing lengthening contractions. For sports that involve running, downhill sprints work well. Prepare your legs to better handle a period of hard run training by performing a few short, relaxed downhill sprints twice a week for two weeks.
Ramp Up Slowly
The amount of inflammation you experience after a workout is always proportionate to how much harder than normal that workout is. Of course, you won't improve your fitness level if you don't increase the intensity of your workouts. But you can minimize post-exercise inflammation and still gain fitness if you ramp up your training gradually, making each hard workout only slightly harder than the last.When training for tough events such as triathlons and marathons, begin preparing many weeks in advance, so you don't have to rush yourself into shape. For example, allow at least 18 weeks to train for a marathon.
Get Your Omega-3s
Eating a diet rich in omega-3 essential fatty acids may reduce the amount of post-exercise inflammation you experience. These nutrients have a number of important biological functions that include the production of anti-inflammatory compounds called prostaglandins.
As you've probably heard many times, the human body is unable to produce the omega-3 fatty acids EPA and DHA, so you have to get them in your diet. Good sources include fatty fish such as salmon and tuna, flax seeds and flax oil, walnuts and soybean oil.
Eat for Recovery
Consuming protein before and during exercise has been shown to reduce exercise-induced muscle damage, which in turn lowers post-exercise inflammation. For example, a James Madison University study published in the September 2006 Medicine & Science in Sports & Exercise found that a protein-fortified sports drink was four times more effective in preventing muscle damage during exercise than a conventional sports drink.
Eating protein within the first two hours after a workout reduces post-exercise muscle damage caused in part by inflammation. Consume only the most easily digested forms of protein, such as a powdered whey protein drink, before and during exercise. After exercise, any healthy high-protein (10 to 15 grams) food will do. Fifteen grams is about the most an athlete can process after a workout.
Matt Fitzgerald is a runner, triathlete, coach and author of several books on fitness and nutrition, including Performance Nutrition for Runners (Rodale, 2005). He is also an International Society of Sports Nutrition-certified sports nutritionist.