IS IT BAD TO HAVE "STIFF" MUSCLES?
Stiff muscles are a counterintuitive superpower of NBA athletesPhilip Anloague, University of Dayton
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.
"Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes."
(Nicol van Dyk, Fearghal P Behan, Rod Whiteley, British Journal of Sports Medicine. Published Online First: 26 February 2019. doi: 10.1136/bjsports-2018-100045)
Research question Does the Nordic hamstring exercise (NHE) prevent hamstring injuries when included as part of an injury prevention intervention?
Design Systematic review and meta-analysis.
Eligibility criteria for selecting studies We considered the population to be any athletes participating in any sporting activity, the intervention to be the NHE, the comparison to be usual training or other prevention programmes, which did not include the NHE, and the outcome to be the incidence or rate of hamstring injuries.
Analysis The effect of including the NHE in injury prevention programmes compared with controls on hamstring injuries was assessed in 15 studies that reported the incidence across different sports and age groups in both women and men.
Results There is a reduction in the overall injury risk ratio of 0.49 (95% CI 0.32 to 0.74, p=0.0008) in favour of programmes including the NHE. Secondary analyses when pooling the eight randomised control studies demonstrated a small increase in the overall injury risk ratio 0.52 (95% CI 0.32 to 0.85, p=0.0008), still in favour of the NHE. Additionally, when studies with a high risk of bias were removed (n=8), there is an increase of 0.06 in the risk ratio to 0.55 (95% CI 0.34 to 0.89, p=0.006).
CONCLUSIONS: Programmes that include the NHE reduce hamstring injuries by up to 51%. The NHE essentially halves the rate of hamstring injuries across multiple sports in different athletes.
THE PROBLEM WITH SCREEN TIME
Around 30% of patients I treat have a complaint that is caused by prolonged sitting, commonly in front of a screen. This is mostly neck and back pain caused by things like; getting stuck at the desk too long, long commutes, long-haul flights, binge watching Netflix on the lounge, or looking at the iPad in bed.
This is a relatively new activity for humans and we're just not used to it. From an evolutionary point of view, we're just not adapted to sitting still all day. We've had 100,000 generations of hunting and gathering, moving around, doing different things all day. We've had 50 generations of agriculture, and only 10 generations of industry, where we're expected to sit and do the same repetitive task for prolonged periods of time. We're just not used to staying still from 9-5. Our bodies have evolved to move and be used. Staying still makes us sore.
NOW, WORSE THAN EVER
COVID-19 has caused a unique moment in time, with unprecedented social and workplace disruption. Never before have so many people been required to work from home. People are working at the dining table or kitchen bench. People are on their laptops on the lounge or in bed. The home set-up isn't ideal.
Also, some of the usual workplace activities that might get you away from the screen, like getting into the boardroom for a meeting, are now happening online too, so there are less reasons to get up and move away from what you're doing.
My workload has decreased with people self-isolating, but every new patient I've had in the last two weeks has been someone with neck pain or back pain caused by working from home.
So remember, if you're getting a sore neck, or a pain next to your shoulder blade, get up and more around more. It's time to take a break.
If you're getting a sore back, or an ache into the top of your buttock, get up and move around more. It's time to take a break.
It should be very simple. Motion is lotion. Rest is rust.
I CAN HELP
If you need help, come in for an assessment and treatment. Physiotherapy is deemed an essential service, and we are still open. Phone 99696925, or book online HERE.
Alternatively, if you're self-isolating, or practising social-distancing due to COVID-19, you can book a video consultation HERE.
Stay safe and well.
PT Inquest, my favourite physio podcast, recently discussed this paper:
Misconceptions and the Acceptance of Evidence-based Nonsurgical Interventions for Knee Osteoarthritis. A Qualitative Study
The abstract summarises:
In contrast to best practice guidelines for knee osteoarthritis (OA), findings from several different healthcare settings have identified that nonsurgical treatments are underused and Total Knee Replacement surgery is overused. Empirical evidence and qualitative observations suggest that patients’ willingness to accept nonsurgical interventions for knee OA is low.
Participants’ beliefs about knee OA and its treatment were identified. Beliefs were grouped into five belief dimensions:
The participants' beliefs are what I would guess, based on what I hear from patients everyday:
The authors conclude:
Common misconceptions about knee OA appear to influence patients’ acceptance of nonsurgical, evidence-based treatments such as exercise and weight loss.
Once the participants in this study had been “diagnosed” with “bone-on-bone” changes, many disregarded exercise-based interventions which they believed would damage their joint, in favor of alternative and experimental treatments, which they believed would regenerate lost knee cartilage.
These misconceptions do feel like commonsense and, as such, are widely held by the general public. Some of them may be true at the very end stage of osteoarthritic disease, but they are definitely not true for all patients with osteoarthritis, and as such, the misconceptions are harmful because patients disregard beneficial conservative treatments like weight loss and exercise, and rush towards surgical options.
"BONE ON BONE" is a metaphor that is commonly used, even by physios and knee surgeons.
"Bone on bone" creates a very dramatic image of what's going on in the knee, and undermines the possibility of osteoarthritis being pain free. Using words like "bone on bone" can cause harm because it sounds like it is definitive and painful, when in reality it's only a metaphor.
The reality could be explained more like: "the joint reinforces and repairs the damaged area by laying down new tissue". Or, "the joint wants to make itself even stronger than cartilage, so it lays down stronger building blocks - bone cells".
Not everyone with osteoarthritis has "bone on bone", and the perception of "bone on bone" as what's happening in the knee can make patients less likely to stick with evidence-based conservative treatment options.
The concept of "WEAR AND TEAR" makes sense if you imagine the joint as mechanical. A cupboard's metal hinge can be opened and closed a certain number of cycles before it breaks. Metal and plastic fatigues and fails. Mechanical joints "wear out". But our joints aren't made of metal and plastic. Knees are not mechanical joints. They are biologically active joints, that adapt to what we do.
If we do a million bicep curls, we don't expect our biceps to "wear out" - we expect to end up with bigger, stronger biceps. Similarly, the bones, cartilage, ligaments and muscles in our knees are biologically adaptive, they have regenerative ability, and adapt to what we do. Our joints get stronger with use.
Rather than "wear and tear", the more appropriate phrase should be: "use it or lose it".
DOESN'T RUNNING "WEAR OUT" KNEES?
Another common misconception is that running "wears out" knees.
Doctors and knee surgeons see patients complaining they have sore knees when they run. The X-ray shows some arthritis, so it's very easy to make the assumption that running causes arthritis. But we know that distance runners don't "wear out" their knees. Runners have better knees than non-runners.
This 2017 research comparing 2,637 runners to non-runners (matched for age, weight, mileage, injury, and other variables) concludes: There is no increased risk of symptomatic knee OA among runners compared with non-runners. In those without OA, running is not detrimental to the knees.
This 2008 research concludes: Long-distance running among healthy older individuals was not associated with accelerated radiographic OA, and long-distance running or other routine vigorous activities should not be discouraged among healthy older adults out of concern for progression of knee OA.
This 2004 research concludes: The results of this literature review strongly suggest that regular mild-moderate impact exercise does not increase the risk of OA, and that there is some evidence that it does not increase symptoms in patients with mild-moderate OA. And: Regular running increases joint space width.
Tendinopathy (tendon pain) is very common. They are the most common type of overuse injury (ref). Achilles tendinopathy affects the majority of runners (ref) and is the reason 16% of athletes have to stop sports participation (ref).
There are a range of commonly prescribed treatment options for tendinopathy, but very few are supported by quality, randomised, prospective, placebo-controlled trials.
SO WHAT DO I DO?
Considering all the available treatment options, above anything else, I always recommend:
WHAT ABOUT INJECTIONS?
Having mapped out a management plan, patients will routinely ask my opinion on getting an injection. They may have had a friend for whom an injection worked well, or the GP has suggested it as an option, or they’ve had one before and it worked.
There are a range of drugs to inject into or around a tendon, depending on who you are referred to:
Corticosteroids are an anti-inflammatory medication injected around the tendon to decrease pain that is caused by inflammation (although it is now thought that inflammation does not play a significant role in tendon pain). Corticosteroid injections have historically been commonly prescribed but more recently their use is controversial. Repeated corticosteroid injections can weaken the tendon and increase the risk of rupture. Corticosteroid injections are good at relieving pain in the short term (2-6 weeks) however, there is strong evidence that long-term outcomes (> 6 months) are worse than other conservative treatments or no treatment at all (ref).
PROLOTHERAPY / SCLEROTHERAPY
Prolotherapy injections act as an irritant causing an inflammatory response then scarring of the nerves that transmit pain. There is no solid support in the medical literature for this procedure for the treatment of tendinopathies. A randomised controlled trial of polidocanol injections showed the potential to reduce tendon pain in patients with chronic painful mid-portion Achilles tendinopathy (ref). However, a systematic review found limited results for use of prolotherapy in sports related soft tissue injuries (ref).
AUTOLOGOUS BLOOD INJECTIONS
The rationale of autologous blood injection consists of enhancing tendon healing through collagen regeneration and the provision of cellular mediators. Good experimental models are lacking, and clinical application is anecdotal. A 2013 randomised controlled trial investigating the efficacy of autologous blood injections as a treatment for mid-portion Achilles tendinopathy concluded they did not reduce pain or improve function any more than a strengthening program. (ref)
The suggested mechanism of high-volume injections is the mechanical disruption of local tissues then stimulates a healing response. One study (ref) has shown that high-volume injection of normal saline solution, corticosteroids or anaesthetics reduces pain and improves short and long-term function in patients with Achilles tendinopathy. However, more research is required.
PLATELET RICH PLASMA (PRP)
Platelets are naturally occurring in your blood, where they play an important role in healing damaged tissue, so superficially it’s inherently appealing to just add more of them to the sore spot. PRP injections are particularly trendy at the moment and it’s easy to find someone who will tell you they work well. Unfortunately, research concludes there is no benefit to PRP injections. This study found PRP injections do not improve plantar fasciopathy pain or function. This study concluded there is insufficient evidence to support the use of PRP for treating musculoskeletal soft tissue injuries. This systematic review found strong evidence against platelet-rich plasma injections for tennis elbow. This study found PRP did not improve tendon structure. This meta-analysis found no greater clinical benefit of PRP over placebo or dry needling for tendinopathy.
Would I have any of these injections, or would I recommend them to my patients, friends, or family? Well it depends. In my experience some people get some benefit some of the time. HOWEVER, these injectables are not consistently effective and their use is mostly not supported by research. I suggest that patients try the strengthening program and the results will be overall better in the long term.
WHY DO THE INJECTIONS WORK FOR SOME PEOPLE?
I’ve been frustrated with a couple of patients that cancelled their follow-up appointment and, when I phoned and asked what had happened, they’ve had an injection and now feel fine. My conclusion is the injections don’t work, but if you were sore and now you’re not, your conclusion would be they do work. So what is it?..
REGRESSION TO THE MEAN
Most people seek treatment when they are at their worst. By definition the only possible change from being as bad as at can be, is an improvement. Was it the injection working, or was it getting better anyway?
Some conditions are self limiting and will just get better by themselves. Did the injection work, or was it about to get better anyway?
I understand that getting an injection seems like a much easier option than doing 12-weeks of strengthening exercises, but in the long run, a strengthening program is the thing that actually works.
If treating tendon pain was as easy as getting an injection then that’s what everyone would do first. Unfortunately it’s not as easy as that.
Have you had an injection for your tendon?