Training Center: Why muscle soreness is a good thing

Feeling sore after your last workout? New science suggests that's a good thing.

Training doesn’t make us stronger. In fact, it initially makes us weaker. It’s a tough concept to swallow, but it’s actually through recovery that we gain strength as athletes. During that time, our bodies repair damage; if the training stress is large enough, we come back stronger. That is the fundamental principle of exercise science.

Muscle soreness is a literal expression of that principle. So, is it something that should be treated or allowed? New science suggests we could benefit from embracing the burn.

“If you rode really hard, did a lot of sprints, burned a lot of matches, that [soreness] means you gave it a good go out there,” says Dr. Jason Glowney, director of the University of Colorado Sports Medicine and Performance Center.

The dogmatic belief that soreness is just a nuisance caused by lactic acid accumulation may follow traditional thinking, but that has been all but debunked.

In fact, our understanding of exercise-induced muscle soreness has changed radically over the past few decades. What was once believed to be a side effect of lactic acid, and then later muscle damage, is now considered to be a complex and necessary inflammatory process that repairs and helps muscles adapt, just as that fundamental principle predicts.

The theory that muscle damage caused soreness came from research on eccentric contractions—the forceful lengthening of a muscle (e.g. lowering a heavy weight). Eccentric contractions are the most common cause of soreness, especially delayed onset muscle soreness (DOMS). The theory claimed that muscle damage triggered inflammation.

“When we get inflammation, we get a little bit of swelling,” says Dr. Ben Rattray, an assistant professor at the University of Canberra Research Institute for Sport and Exercise. “And we know that swelling is strongly associated with a pain response.”

Thus, treatment focused on reducing the unwanted inflammation.

Eccentric contractions are very common in activities like weightlifting, plyometrics, and running, but almost non-existent in cycling. Riding a bike involves non-damaging concentric motions. Which raises the question: If DOMS doesn’t result from cycling, what causes inflammation, soreness, and the consequent adaptations in cyclists?

The answer may lie in recent research showing that muscle damage is not necessary for inflammation or soreness to occur. In fact, DOMS appears to occur independent of muscle damage.

A 2008 review in Sports Medicine found that metabolic strain and overuse from long fatiguing endurance work can produce inflammation similar to eccentric muscle damage.

According to a 2016 review of exercise-induced damage and inflammation led by Jonathan Peake, the latest research is changing the theory about soreness and inflammation. No longer seen as an unpleasant side effect that is detrimental to recovery, inflammation is increasingly seen as a very necessary part of muscle remodeling and training adaptations.

“If you don’t provoke [inflammation], you don’t get an adaptation,” Rattray says.

In 2016, researcher Bénédicte Chazaud outlined in Immunology and Cell Biology a complex three-stage process of muscle inflammation and remodeling. While a multitude of immune cells and chemicals are involved, a particular type of immune cell called a macrophage is central to every step. These cells also promote muscle satellite cells to activate and form new muscle tissue. Another player critical to the process is cyclooxygenaise-2 (COX-2), which causes pain. In fact, over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs; e.g. aspirin, ibuprofen, etc.) generally target COX-2.

Why is this important?

Many traditional recovery strategies focus on inhibiting inflammation and pain by targeting macrophage activity and COX-2. But the timing and successful completion of all three stages of inflammation is necessary for proper repair and remodeling. Interruption or prevention of any stage can inhibit repair, prevent adaptations or the formation of new muscle tissue, cause fibrosis in the muscle (scarring,) and lead to injury.

As athletes, we strive to optimize our recovery, and rightfully so. Therefore, this new perspective, which suggests doing things that seem to contradict recovery, can be a tough idea to wrap our heads around.

“But the question that comes back more and more often these days is when you try to promote recovery, are you actually blunting the adaptation response?” asks Rattray.

Being okay with being sore

If you want to get stronger, soreness is a given. Still, there are ways to reduce the pain without interfering with the repair and remodeling process.

Wear your pain with pride
Mild exercise does not produce an inflammatory response. It takes moderate to hard training to elicit adaptations. So, there may be something to the phrase “no pain, no gain.”

Address the pain before the big race
Soreness may be part of getting stronger, but it can still kill performance. If you’re a few days from a race, try to reduce soreness with massage, compression clothing, and cold therapy.

Generally avoid NSAIDS
Anti-inflammatory drugs can reduce inflammation and soreness. But they also interfere with the repair process and hurt training adaptations. Worse, they can cause fibrosis.

Try massage
Getting a massage soon after damaging exercise has been shown to reduce inflammation and pain. It may also help performance by promoting a key regulator of endurance training gains. Using a foam-roller has been shown to have similar effects to massage.

Be careful with cooling
While icing can speed recovery, both icing and topical cooling have been shown to hinder muscle regeneration in a similar fashion to aspirin. However, cold-water immersion may help to keep soreness down and allow your legs to perform better if a race is around the corner.

Compression clothing
Reduced soreness and faster restoration of strength has been observed with compression cloth- ing. Like cooling, it is an effective strategy for recovery before key races.

Restore carbohydrates and protein
Rattray notes that glycogen depletion may contribute to fatigue and inflammation. He has also found that fatigue may start in the brain. Increased carbohydrate and protein ingestion for several days after damaging exercise can reduce soreness, speed repair, and reduce brain fatigue.

Take advantage of the “repeated bouts effect”
While this concept applies primarily to eccentric exercise, the best way to consistently avoid future soreness is with prior eccentric exercise. The “repeated bouts effect” seems to make repair and inflammation more efficient the next time around, and can last between six to nine months.

Do off-the-bike work
There is some evidence that the repeated bouts effect may generally make muscle repair more efficient. So, doing regular eccentric off-the-bike work, such as weights, running, or plyometrics, may help your training and recovery on the bike.

Trevor Connor is a long-time cycling coach and elite racer. He holds degrees in exercise physiology and nutrition from Colorado State University. He has served many roles in cycling, from team manager to coach at the National Centre in Canada.