What Foam Rolling Really Does to Your Muscles

To the man with a hammer, every problem looks like a nail.

And to the annoying guy in the gym who’s just “discovered” foam rolling, and now feels compelled to offer you his unsolicited advice on the subject, every physical ailment is one that can be fixed with the help of a foam roller.

Tight hamstrings? Roll them.

Knee pain? Roll your IT band.

Bad back? Roll it.

Despite the eagerness of some to jump on a foam roller whenever the opportunity presents itself, there is currently very little research data to show exactly what foam rolling does or how it works.

While a recent study lends support to claims that it reduces post-exercise muscle soreness, it also appears to make muscle damage worse rather than better.

The study involved a group of 20 men, who were assigned to a control or foam rolling group [1]. Both groups were required to complete 10 sets of 10 reps of squats using 60% of their 1-RM, with 2 minutes of rest between each set.

The only difference was that one group did some foam rolling at the end of the workout. They did the exact same thing at the end of two testing sessions, which were carried out 24 and 48 hours after the workout.

The foam roller was a PVC pipe surrounded by a thin layer of foam. This was used because it places greater pressure on the soft tissues than foam rollers made from softer material (polystyrene foam).

Subjects in the foam rolling group performed five different exercises, targeting the front, side, rear, and inner parts of the thigh, along with the gluteal muscles. They did each of the five exercises on both the right and left legs for two 60-second bouts each.

The result?

Foam rolling led to a substantial reduction in muscle soreness while improving vertical jump height, voluntary muscle activation, as well as both passive and dynamic range of motion in comparison with the control group.

The figure below shows the average change in post-exercise ratings of muscle soreness. The dark triangles show the results for the control group, while the circles represent ratings of muscle soreness in the foam rolling group.

As you can see, muscle soreness in the foam rolling group was substantially lower than the control group at 24, 48 and 72 hours after the workout.

During the post-workout testing sessions, subjects who had used the foam roller were able to jump just as high as they had before doing the squat workout. Vertical jump height in the control group dipped by around 5%, eventually returning to baseline levels 72 hours later.

So far so good. But there is a twist in the tale.

The researchers also placed electrodes on the subjects’ thighs and used a high voltage electrical stimulator to measure the contractile properties of the muscle itself.

When you contract a muscle, you’re involving not just that muscle, but the network of nerves connecting that muscle to your brain. Using electricity to stimulate a muscle contraction takes much of the nervous system out of the equation, allowing you to measure what’s happening in the muscle itself.

Interestingly, muscle fibers in the foam rolling group were able to produce less force than those in the control group. The researchers think this could result from an increase in muscle damage caused by foam rolling.

“The present findings suggest that although foam rolling may be beneficial in treating connective tissue damage, minor damage to muscle tissue may incur,” they write. “Whether this is beneficial for the repair process occurring in the muscle or only causing more damage to the muscle is unknown.”

So what’s going on? How did foam rolling reduce muscle soreness while appearing to increase muscle damage?

Firstly, I should point out that the researchers didn’t actually measure muscle damage. They found a reduction in the ability of a muscle to produce force during an electrically stimulated contraction, and assumed that muscle damage was the cause. But they didn’t extract a slice of muscle tissue and look at it under a microscope to see if there were any visible signs of damage.

Delayed-onset muscle soreness (DOMS) is associated with damage to muscle cells. But the former is not necessarily caused by the latter. Instead, DOMS appears to result from damage to connective tissue rather than the actual muscle itself. An increase in DOMS doesn’t always reflect an increase in muscle damage, and a decrease in DOMS is not always indicative of less muscle damage.

We know from other studies that even a relatively small amount (20 seconds) of rolling leads to a short-term increase in range of motion [3]. However, the effect appears to be primarily neuromuscular in nature.

In other words, rather than altering the mechanical properties of connective tissue, foam rolling leads to temporary changes in the nerve impulses that travel between the brain and the muscle [4]. It’s an effect that wears off relatively quickly, and is unlikely to explain the reduction in post-exercise muscle soreness seen in this study.

Instead, the researchers think that the reduction in DOMS after foam rolling comes from a reduction in inflammation and increase in mitochondrial biogenesis:

“Foam rolling likely acts by reducing neural inhibition due to accelerated recovery of the connective tissue as a result of decreased inflammation and increased mitochondria biogenesis, decreasing nociceptor activation, allowing for better communication from afferent receptors in the connective tissue.”

Again, this wasn’t something they measured directly. Rather, it’s an assumption based on the results of an earlier study – which itself has come to some rather questionable conclusions – that looks at how massage after exercise affects inflammatory signalling and mitochondrial development [2].

A reduction in post-exercise muscle soreness is seen by most people as a good thing. But interfering with the normal post-training response may have a negative impact on the way your muscles adapt to that training. DOMS may be a perfectly natural side effect of a recovery process that should be left well alone.

By itself, this study doesn’t tell us whether foam rolling after exercise is a “good” or a “bad” idea. All it shows is that foam rolling seems to have an effect on both connective and muscle tissue that persists for at least 24 hours.

Crucially, we don’t know whether the effect that it does have will impair or improve your results over time. You’d need to look directly at training adaptations over a longer period (e.g. 12-16 weeks) to get a better idea about what’s really going on.

Final Thoughts

Foam rolling reminds me a bit of stretching back in the day. Sore after exercise? You didn’t stretch. Injured? You didn’t stretch.

Then the research came along and showed that stretching didn’t do a lot of the things it was supposed to. In some cases, it was found to hinder rather than help performance.

My guess is that we’ll see the same kind of thing with foam rolling. It will prove to be useful for certain things, and not so useful for others. In some cases, the effects may turn out to be negative.

Don’t get me wrong – I’m not knocking foam rolling. Here at Muscle Evo HQ, I have both a foam roller and a rumble roller. I’ve used both at various times to help me deal with various “niggles” that have accumulated over the years.

But a lot of people are using a foam roller simply because it’s the trendy thing to do, rather than because it’s the best tool for the job.

References
1. Macdonald GZ, Button DC, Drinkwater EJ, Behm DG. (2014). Foam rolling as a recovery tool after an intense bout of physical activity. Medicine and Science in Sports and Exercise, 46, 131-142
2. Crane JD, Ogborn DI, Cupido C, Melov S, Hubbard A, Bourgeois JM, Tarnopolsky MA. (2012). Massage therapy attenuates inflammatory signaling after exercise-induced muscle damage.
Science Translational Medicine, 4, 19ra13
3. Sullivan KM, Silvey DB, Button DC, Behm DG. (2013). Roller-massager application to the hamstrings increases sit-and-reach range of motion within five to ten seconds without performance impairments. International Journal of Sports Physical Therapy, 8, 228-236
4. Schliep, R. (2003). Fascial plasticity – a new neurobiological explanation: Part 1. Journal of Bodywork and Movement Therapies, 7, 11-19