Stiff muscles are a counterintuitive superpower of NBA athletes

For most people, the term “stiffness” has negative connotations. When you wake up in the morning complaining of a “stiff back,” the remedy might include taking a hot shower, doing some yoga, swallowing aspirin, or visiting a physical therapist to loosen up. Stiffness is typically viewed as unpleasant and can limit one’s physical activities.

Surprisingly, though, for elite athletes like professional basketball players, muscle stiffness is not only something that is necessary, you could say it’s their superpower. As a physical therapist and researcher who works with National Basketball Association players, I’m interested in understanding the key factors that help to minimize injury risk and maximize performance in elite athletes – and understanding stiffness is an important part of that.

Spring in your step

Physiologists think of muscles as being like biomechanical springs. Muscles contract to produce forces that help you move and stretch to allow enough range of movement. Stiffness is a way to talk about how springy a muscle is. It is a characteristic of how much it can lengthen in response to an applied force. The spring of a muscle allows it not only to stretch but also to recoil during muscle contraction. This process allows for movements including walking, running and jumping.

The force required to deform or stretch a muscle is correlated to a degree of spring or stiffness and to the extent the muscle is lengthened. Strength is important, but stiffness can help an athlete generate even more power.

Basketball is a vertical sport that includes up to 46 jumping and landing activities for an individual player per game. That’s 2 to 4 times more jumping than in soccer or volleyball. It’s also a multi-directional sport – an average player changes direction or activity every 2 to 3 seconds, requiring constant acceleration and deceleration of movements.

Lower extremity stiffness is important for optimal basketball performance because athletes who appropriately use greater stiffness characteristics can take advantage of the elastic energy it creates. A muscle can only stretch so far because its length is limited by its degree of stiffness. So, like a spring or a rubber band, when the muscle is stretched, that stiffness helps to create elastic energy that can then be used with a muscle contraction to help you run or jump on the court.

This helps someone like Russell Westbrook leap in the air, stop on a dime, then accelerate down court during a fast break. It takes him just 3.36 seconds to run from baseline to baseline.

The sweet spot

However, there is a point of diminishing returns. Too much muscle stiffness can lead to reduced joint motion and a decreased ability to absorb shock at the joints. This can place one at greater risk for stress fractures or even osteoarthritis, the wear and tear of cartilage that can cause joint pain. Evidence suggests that too much stiffness may lead to injury.

And on the other side of the spectrum, a player needs a certain degree of flexibility and joint mobility to support the proper elongation of muscle and tendons that allow for the appropriate range of motion.

So players need to balance these extremes, landing in the sweet spot of optimal lower extremity stiffness: not too much, which can lead to high levels of force and loading rates and a greater risk for bony injuries. And not too little, which is associated with an increased risk for soft tissue injury and muscle strains.

My research team is investigating these relationships in an attempt to help elite athletes minimize risk of injury and maximize performance. The first step is in understanding what “normal” clinical measurements are for elite athletes.

Textbook values have been established for the general population but this information is lacking for NBA players. For example, a typical value of ankle flexibility for the average individual is about 50 to 55 degrees. Our research team has found that the typical NBA player is more stiff and averages 35 degrees.

When comparing elite basketball players to textbook norms it might appear that they are too tight and even dysfunctional. However, to be successful in their sport, this degree of stiffness is actually their superpower. If trainers start stretching Lebron James’ muscles to match the textbook values of the general population, he may start jumping like the general population. That tactic could very well be kryptonite to an NBA athlete.

Training to minimize injury and maximize performance

Physical therapists know that the so-called fast twitch muscle fibers – the ones responsible for jumping and sprinting – have a higher propensity for stiffness. With training the level of stiffness can be increased to improve performance.

Evidence suggests that plyometric and bounding exercises that involve jumps, hops, or bounds, performed in a stretch shortened cycle do have a positive effect in the ability for muscle to have more spring. But overall, your own degree of stiffness versus springiness is a combination of nature and nurture, genetics and training.

Research related to better understanding the continuum between stiffness and compliance can help physical therapists and trainers when working with basketball players. They need to know dosage – how much to stretch or strengthen. Work is underway that contributes to this endeavor. There are also initiatives that aim to understand player load and the cumulative physical demands that elite athletes undergo when generating fast and powerful movements. Researchers also need to understand what the best methods and technologies are for monitoring these loads. My colleagues and I theorize that there is an optimal level of compliance and stiffness that helps keep our basketball heroes super.

Philip Anloague, Chair and Associate Professor of Physical Therapy, University of Dayton

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Needless procedures: knee arthroscopy is one of the most common but least effective surgeries

From time to time, we hear or read about medical procedures that can be ineffective and needlessly drive up the nation’s health-care costs. This occasional series will explore such procedures individually and explain why they could cause more harm than good in particular circumstances.

More than 70,000 knee arthroscopies were performed in 2011 in Australia and, though rates of the surgical procedure are now falling, it still remains one of the most common surgical procedures.

The word arthroscopy means to look inside a joint, in this case the knee. But newer imaging techniques, such as magnetic resonance imaging (MRI) scans, mean performing a knee arthroscopy simply to look inside the knee joint is rare.

Knee arthroscopies are most commonly performed to treat osteoarthritis (wear and tear in the joint) or problems with the menisci (the two rubbery discs between the bone ends). An arthroscopy involves making a small incision in the skin and inserting a kind of camera on a stick. Another incision is made to insert other instruments to cut and remove tissue.

In the case of osteoarthitis or meniscal problems, arthroscopy can be used to clear debris from the joint or to trim loose cartilage or torn parts of the menisci. The procedure can also be used to perform ligament reconstructions, help with treating fractures or infections in the knee, or simply to take a sample of tissue from the joint.

The camera can see structures such as the cartilage that covers the end of the bones, the lining (synovium), the menisci and ligaments. Knee arthroscopy requires admission to hospital and an anaesthetic. It carries some risk of harm such as infection or further damage in the joint.

Read more: Spinal fusion surgery for lower back pain: it's costly and there's little evidence it'll work

It’s rarely effective

Most knee arthroscopies are done in older people for degenerative conditions such as osteoarthritis. The prevalence of knee osteoarthritis, which can involve wear and tear of the menisci as well as the cartilage that lines the bone, increases with age. Most people aged 50 years and over have some osteoarthritis in the joint and roughly one-quarter will have some wear and tear in the menisci.

Many people with osteoarthritis or a torn meniscus also have knee pain. This has led to the belief that the osteoarthritis changes or the meniscus tear cause the pain. But these changes are also common in those who have no pain at all. And menisci mostly don’t have nerves, so they can’t be felt unless there is a large tear, often resulting from a major injury. In fact, most people with a torn meniscus don’t have knee pain.

Many studies have now shown the outcomes from arthroscopic surgery for osteoarthritis and degenerative meniscal tears are no better than the outcomes from placebo (fake) surgery or other treatments (such as exercise therapy).

A recent summary of these studies made “a strong recommendation against the use of arthroscopy in nearly all patients with degenerative knee disease” (osteoarthritis and degenerative tears of the menisci) and concluded “further research is unlikely to alter this recommendation”.

Many surgeons believe the presence of mechanical symptoms – a concept that is not clearly defined but involves pain and abnormal feelings (such as catching, clicking and locking) when moving the joint – can be treated with arthroscopy. However, studies have also shown having arthroscopy does not provide better results than fake surgery for the treatment of mechanical symptoms.

Sometimes, a meniscus can be so badly torn it folds over on itself, jamming the knee and restricting the ability to straighten the knee. This is a relatively uncommon type of meniscus tear and if the symptoms don’t improve on their own, the torn part of the meniscus can be removed arthroscopically.

Why do surgeons still recommend it?

Doctors tend to overestimate how good their treatments are and underestimate the harms that come from them. Surgeons are often faced with patients in pain and, other than surgery, have little else to offer except continued non-operative treatment, reassurance and time.

Read more: Explainer: what is pain and what is happening when we feel it?

Patients may want a quick fix or may have failed to improve with other treatments, but unfortunately the failure of other treatments doesn’t make knee arthroscopy any more successful.

Knee pain due to osteoarthritis often fluctuates in severity and patients tend to present for treatment when their pain is most severe. This means any treatment given at this time will appear more effective than it truly is. This is why comparative studies, particularly placebo studies, are important, as these show the true effects of treatments.

Though some surgeons may believe they can predict which patients will do well from surgery, this belief has not been validated. Despite the desire for this procedure to work, arthroscopy for degenerative knee conditions puts patients at risk of harm, including death, for no important benefits.

How can we stop it?

Changing practice in response to evidence is often slow. The first high-quality trial to demonstrate knee arthroscopy was no better than placebo surgery was published in 2002, yet overuse of knee arthroscopy has persisted.

Barring financial and regulatory controls, practice change in medicine is largely a social phenomenon. It requires leaders in the field and informed consumers to change practice.

The rates of knee arthroscopy in Australia are starting to fall, particularly in New South Wales, where the rate of knee arthroscopies in people aged 50 and over has nearly halved since 2011. More action is needed. All surgeons, particularly in high-volume states such as Western Australia, South Australia and Victoria, need to take a good hard look at the evidence, question their practice, and take action to reduce this overuse.

Read more: Needless medical procedures: when is a colonoscopy necessary?

Ian Harris, Professor of Orthopaedic Surgery, UNSW; Denise O'Connor, Senior Research Fellow, Monash University, and Rachelle Buchbinder, Professor of Clinical Epidemiology and Rheumatologist

This article is republished from The Conversation under a Creative Commons license. Read the original article.