As a runner, your performance obviously depends on the condition and efficiency of your leg muscles. But have you ever considered whether the quality — not just the quantity — of your muscles matters? Believe it or not, studies show that muscles of equal size and volume do not necessarily have equal strength and power. In other words, you and a friend may have the same thigh circumference, but tire out after a different number of squats or leg presses. This capacity of a muscle to produce force per unit of volume is called “muscle quality,” or MQ.
[See: The 10 Best Exercises You Can Do for the Rest of Your Life.]
Although MQ was originally thought of as a medical issue, we now know that it’s also important in sports and exercise. Dr. Tim Noakes, an internationally-recognized researcher and avid marathon and ultramarathon competitor, was one of the first scientists to highlight the importance of MQ for runners. In his now iconic book, “The Lore of Running,” published in 1985, he stated that reduced MQ was one possible cause of the age-related fall in aerobic fitness.
What exactly is MQ?
Think of a muscle as being made up, broadly, of two major types of tissue: one that contracts (contractile tissue) and one that does not (non-contractile tissue). MQ is determined by the relative amounts of these tissues in your muscle. The greater the proportion of a muscle’s contractile tissue to its non-contractile tissue, the greater the amount of force it can produce for its size, and the greater its MQ.
Contractile tissue, which is made up of specialized fibers that enable the muscle to exert force, is just as important in aerobic exercises like running as they are in anaerobic exercises like strength training. Non-contractile tissue, which consists mainly of connective and fatty tissue, is also important to muscle in different ways. Connective tissue provides structural integrity for the muscle, and fat deposits inside muscle can be a source of energy. However, when fat accumulates in excess, it increases the non-contractile percentage of the muscle and reduces MQ. In other words, even though the muscle may not visibly shrink, its ability to produce force will diminish.
How can MQ affect your running?
Differences in MQ can occur not only between individuals, but, perhaps more importantly for runners, also between the same muscles on different sides of the body. If your right leg’s MQ is greater than your left leg’s MQ, for example, it will produce greater force during running. This can result in subtle hip and leg alignment differences that may reduce running efficiency and, over time, increase your risk of injury.
[See: 8 Lesser-Known Ways to Ruin Your Joints.]
While MQ isn’t necessarily reflective of your fitness level — even professional cyclists’ and runners’ MQs differ widely, as do their own right and left leg MQs — strong evidence suggests that equalizing differences between legs will increase performance and reduce the risk of injury.
How can you measure MQ?
In part because it’s an invisible trait, MQ has traditionally been hard to measure. Typical MQ calculations involve some kind of maximum strength test of the muscle involved, as well as a measure of its muscle mass or cross-sectional area using sophisticated, expensive and relatively inaccessible electronic equipment.
Fortunately, ultrasound is an increasingly available, convenient and non-invasive way of measuring MQ more directly. In fact, recent advances in technology have produced compact ultrasound devices that connect directly to a USB port and can display the ultrasound image on your tablet or laptop. In these images, muscles show as darker areas, while fat and connective tissue show as brighter areas. When the whole image is digitized, the brighter (non-contractile) parts can be mathematically separated out, enabling MQ to be expressed as a percentage of the scanned muscle. All this can be done automatically “in the cloud” and takes less than a minute. Yes, there is now an app for that!
How can you improve MQ?
There are three ways of increasing MQ: You can increase the strength of the contractile tissue, reduce the amount of the non-contractile tissue or do both simultaneously. How? Ideally through strength training.
[See: 5 Strength Machines You Should Start Using ASAP.]
We already know that this kind of exercise can increase strength and power; more recent research has shown that it can also reduce intramuscular fatty tissue. In effect, you’ll improve your sports performance, reduce your injury risk and boost your daily functioning and health status, whether you’re an athlete or non-athlete, old or young, skilled or an amateur.
More from U.S. News
8 Reasons Running Now Will Help You Later in Life
The 10 Most Underrated Exercises, According to Top Trainers
5 Unintended Consequences of Eating Too Much Protein
What Is Muscle Quality and Why Is It Important? originally appeared on usnews.com
