The Dreaded 'Tennis Cramp'

It was a hot, muggy summer’s day in 2010. After winning the 2nd set, the momentum was on my side going into the 3rd. I had never beaten my opponent, ‘Stan the Man’ as we called him (no not Wawrinka...but a very good player nonetheless). But I felt confident. I was moving well, dictating play...and I continued the good play until 4-1 in the 3rd. And then, after hitting an attacking forehand, I felt my right leg completely seize. I hit the ground, gasping for air, trying not to scream. But the pain was too much. My opponent came rushing over to my side of the court, along with fellow players and spectators...I knew what it was though, this wasn’t the first time I had experienced this sort of pain….it was a cramp.

The Australian summer swing wrapped up the other week. If you followed any of the action, you probably noticed that it was a pretty hot summer overall (they even closed the roof for the men’s final!). A mix of heat, long matches and the stress of the moment can lead to a host of physical ailments - from heat exhaustion to joint pain and more.

The ‘more’ I’d like to focus on today is muscular cramps. While it was an early story for some top players down under (check out the gutrenching video of Muguruza below) , believe it or not, its occurrence isn't strictly limited to hot environments. Myself - and many players that I’ve coached over the years - have experienced  cramps in normal conditions. In fact, during the indoor season I’ve had players cramp on multiple occasions. It can happen during a practice or match, while players are stretching/recovering and other times, it can even happen much later in the day - when on the car ride home or during one’s sleep. Listen, I’ve had my share of cramping episodes and frankly, they’re not any fun (if you’ve ever had one, you understand).

 
 

Misguided Opinions

Many believe it’s a hydration issue - just drink more water. If you know anything about water balance, you’ll know that when rapidly sweating (as occurs during intense tennis play), taking in water isn’t enough. Perhaps muscular cramps come about because mineral and electrolyte imbalances. Have a banana, they'll say. Others argue it’s all about fitness. Brad Gilbert, during an early round Aus Open match, had this to say on the ESPN broadcast when one player began cramping deep in the 5th; “you’ve earned the right to be fitter than your opponent, it’s that simple”. Does BG have a point?

In this post, it’s my aim to answer these questions. We’ll take a look at what the science has to say - in other words, what’s the underpinning cause of cramps and what contributes to their onset. To finish up the post, I’ll offer recommendations on how to mitigate cramps from presenting themselves in the first place AND provide suggestions on how to relieve them if they do occur. If you're not into the underlying causes associated with cramps, at the very least, skip to the bottom to find out how to mitigate/alleviate them. 

What Are Muscular Cramps?

Before we get into some of the causes and treatments, let’s briefly define what muscular cramps are. Previously, muscle cramps were also known as ‘heat cramps’ but research experts have thrown this term to the curb as muscle cramps have also been reported in cooler conditions (like I mentioned above.)..EVEN skiers and other winter sport athletes have experienced cramps. The technical term for muscle cramps is ‘exercise-associated muscle cramps’ or EAMC. We will use cramps, muscle cramps and EAMC interchangeably throughout this article.

Bob Murray, the leading expert on the topic, explains that EAMC are characterized as... “a sudden, involuntary, painful contraction of a muscle or part of it, self-extinguishing within seconds to minutes and...often accompanied by a palpable knotting of the muscle”. I know, the definition sounds just as excruciating as actually going through the pain. But if you’ve ever experienced an EAMC before, you know that in the moment, the pain can be debilitating. Players are literally paralyzed and most of the time, forget about getting up and competing at a high level.

But like I said in the intro, EAMC don’t just occur while you’re playing. Nelson et al (2016) adds that cramps can occur during exercise or immediately after exercise - and from my experiences, can occur several hours later too. On top of that, EAMC can last anywhere from 1 to 3 minutes, are characterized by pain, stiffness and bulging of the affected area and generally occur when the muscle is in a shortened position (this ‘shortened position’ is a key point, so remember it). Common affected areas include the quads, hamstrings and triceps surae (calf complex).

So What Causes Exercise-Associated Muscle Cramps?

According to a recent narrative review by Nelson et al (2016), there are 2 prevailing theories on the occurrence of muscle cramps. Let’s explore each theory in detail:

#1 - The Dehydration and Electrolyte Imbalance Theory

During intense exercise, our body cools itself through sweating. When we sweat, the cells - and in particular, those cells which are associated with muscle contractions - lose interstitial fluid (i.e. a loss of fluid within the cell). The fluids in our cells aren’t just made up of water - they hold a variety of substances including the likes of sodium, potassium, calcium, magnesium and chloride. Excessive sweating can also lead to deficits in these minerals - all of which are important for the function of various processes (including muscle contractions...which help sustain exercise intensity). This essentially leads to an unfavorable environment within the various cells of the body which results in ‘hyperexcitable’ motor nerve terminals (those that innervate muscle and produce contractions) and ‘spontaneous discharge’ (Nelson et al 2016). All of this would, in theory, contribute to some sort of twitch, stiffness or cramp-like activity within that particular muscle.

While this theory is definitely plausible, it has been refuted in recent years as new research has emerged. We’ll get to that research in a minute; but first, why is hydration and electrolyte status not that important? There are several limitations to the previous studies that reported hydration and electrolyte status as being significantly correlated to muscle cramps - 3 of these findings are worth mentioning. First, recent evidence has revealed that both crampers and non-crampers did not have differences in hydration status and serum electrolyte status during endurance events. Second, when hypohydrated (less than optimal hydration) vs hydrated subjects were electrically induced, there was no difference between the onset of cramping and their severity. Lastly, stretching - and activation of Golgi Tendon Organs (GTOs….later we’ll explore the important role of GTOs) have been reported both empirically and anecdotally, to relieve muscle cramps WITHOUT altering hydration and/or electrolyte status (Craighead et al 2017).

So, for those coaches and players that report a decrease in cramp severity (or it’s alleviation entirely) as a result of a Gatorade beverage, ask yourself, was the athlete stretching at the same time? Did enough time pass for the cramp to momentarily dissipate? Or perhaps there’s a placebo effect in place. Regardless, as we’ll see later in the recommendations section, hydration status plays a factor in muscle cramping, but it doesn’t appear to be the root cause.

#2 - The Altered Neuromuscular Control Theory

Before we outline the premise behind this theory, it’s important to know what muscle spindles and GTOs are. And to define these terms we must understand proprioceptors. Proprioceptors are receptors located within muscle and tendon that are capable of detecting changes in the length and force of these tissues. Proprioceptors are constantly relaying information to our conscious and subconscious ‘control centers’ - always providing info as to where we are in space.

Proprioceptors in skeletal muscle are called muscle spindles. Muscle spindles primarily detect changes in muscle length - and when a stretch is detected, they act to produce a rapid contraction (think of the stretch reflex action - i.e. knee jerk). They are excitatory in nature. GTOs are also proprioceptors but they are found within the tendinous structures of muscle-tendon units. Their primary role is to detect changes in force (in both the tendon and the muscle) for protective purposes. If GTOs sense too much tension, they’ll respond by inhibiting the activated muscle or tendon. That means that they are inhibitory in nature. One last point - these receptors have spinal reflex inputs; meaning that the message doesn’t have to be sent to the brain (as this would take too long for a response to be generated).

Why is this info relevant when it comes to cramping? Nelson et al (2016) illustrates this best by stating the following:

“The “altered neuromuscular control theory,” posits that EAMC result from altered reflex control mechanisms in response to neuromuscular fatigue. Specifically, muscle overload and fatigue engender an imbalance of the excitatory drive from muscle spindles and the inhibitory drive from GTOs. The result is an increase in excitatory drive to the alpha motor neuron, which ultimately produces a localized cramp.”

To simplify, when an athlete gets to a point of neuromuscular fatigue, muscle spindles activity increases (i.e. produce contractions...like the bulging experienced during cramping) while GTOs have decreased activity (which doesn’t allow for alleviation of said contractions). This is why cramping usually occurs towards the end of practices and matches -and when players are more likely to hit a muscular fatigued state.

Below we will briefly explore several factors that contribute to muscle fatigue AND all of which relate to the altered NM control theory.

 
 Cramps have a long history in tennis...can we prevent them? 

Cramps have a long history in tennis...can we prevent them? 

 

Factors that Lead to Fatigue and Exercise-Associated Muscle Cramps

1) History of EAMC, Heredity and Genetics

Just like some athletes (people) have different tolerances to pain, when it comes to cramps, some athletes have a lower OR higher cramp threshold. Researchers call this the individual CTF (cramp threshold frequency). CTF is defined as the minimum electrical stimulation required to evoke a cramp. Research has revealed that individuals with a history of cramping also have a lower CTF. Meaning, if you cramp often, you’re likely more susceptible to repeated bouts of cramping in the future.

Do some have a lower CTF because of family history or genetics? The research is unclear on this topic - some cross-sectional findings are in favor while others don’t line up. The verdict is still out on this one.

2) Gender and Age

Research suggests that females are less fatigable compared to males. Proposed mechanisms include a) a greater proportion of type 2 fibers in males (type 2 fibers, in general, fatigue more readily compared to type 1 fibers) and b) females use more lipids (fats) for energy during exercise (since lipids are a more abundant source of fuel, it would in theory, prolong the onset of fatigue). That said, it’s difficult to accurately compare relative intensities of exercise - if we could, we may see differing results.

Age and cramps - while logically, should have an impact - don't seem to be a factor at the moment. But not enough research has been conducted in a systematic fashion to draw any tangible conclusions.

3) Body Size

Logically, an increased proportion of fat mass compared to lean mass would in some way lead to fatigue (sooner), which would then contribute to cramping...but interestingly, as it currently stands, there are no correlations between EAMC and bodyweight or BMI. In one study, taller runners showed a significant correlation to EAMC. The authors proposed that this could be due to differences in biomechanics between shorter and taller athletes - with an increased chance of fatigue in taller athletes.

4) Exercise Intensity and Injury History

There seems to be a high correlation between vigorous exercise and EAMC - not surprisingly. High level tennis requires high intensity effort sustained for long periods - which is why I believe (from experience) that most cramping episodes occur at elite levels of play.

As for injury history, there is some weak evidence that suggests prior tendon and/or ligament injuries are correlated to EAMC. Perhaps due to suboptimal GTO function - as we saw previously

Recommendations

In collegiate settings, one study found that for every 1000 playing hours, elite players reported 1.2 acute, muscle-related injuries. The authors state that most of these were related to cramping (exact figures weren’t provided). Furthermore, in a study of junior and club players, muscle cramps were reported to be the most common musculoskeletal condition. These stats are merely averages - in practical settings, I’ve witnessed the same junior players experiencing cramps on a routine-like basis. It’s frustrating and discouraging. But the science is becoming clearer and we can begin to provide coaches and players with some recommendations - both to mitigate EAMC onset and to treat them if (when?) they do occur.

Here’s what to do IF a cramp presents itself...

Stretch (lightly)

Nelson et al (2016) believe that stretching is the most effective treatment for acute cramping (i.e. relieving a cramp once it’s begun). The reason…proprioceptors in tendon (GTOs), are suppressed when muscle contracts in a shortened position, like during a cramp. When stretched, muscle-tendon fibres lengthen, providing feedback to GTOs so they can perform their role - to inhibit muscle activity, effectively ceasing the contraction and alleviating the dreaded cramp.

Breathe!

Two case reports found that hyperventilation (20-30 breaths/min) relieved cramps entirely - interestingly, in both cases, they DIDN’T return. In my own experiences, performing a series of deep breaths (while at the same time stretching) has had merit. Yes these are isolated cases, but breathing techniques may be an alternative treatment strategy when other means are not available.

Drink Pickle Juice (or some other TRP channel stimulator)

A lot has been said about this on social media of late. It is true? Studies (Miller et al 2010) have found that pickle juice had shorter cramp times in hypohydrated men compared to water (49 seconds shorter). Pickle juice has a high amount of salt and acetic acid. Earlier, it was proposed that because of the high salt content, pickle juice restored electrolyte balances and thus relieved athletes of cramping. However, this has now been discredited as Miller et al (2010) found virtually NO changes in plasma electrolyte concentrations. These researchers hypothesize that, “the decrease in cramp duration was attributed to an inhibition of the oropharyngeal reflex, which reduces alpha motor neuron activity of cramping muscles throughout the body.” In essence, there are strong excitatory receptors in our mouth and digestive tract that can depress whole-body efferent neural output. This is a simplified explanation - a more thorough look deserves an full article on the topic.

Don’t like pickle juice? There are now commercially available products that have been scientifically validated to work in a similar fashion. Personally, I haven’t experimented with them, YET - but worth investigating.

Stay Hydrated and Electrolyt-ed

Salt tablets and magnesium supplementation are commonly used to treat and prevent cramps, but do they work? Likely not - there’s currently no evidence to suggest this is the case.

But just because the dehydration and electrolyte imbalance theory isn't the primary cause of muscular cramps, doesn’t mean players shouldn’t maintain adequate fluid and mineral levels pre, during and post training/competition. A decrease in hydration of just 2% has been linked to severe reductions in performance and increases in fatigue. Recall that fatigue leads to EAMC...but staying hydrated for performance purposes should motivate players enough.

 

Get Rafa some pickle juice already! 

 

Here’s what to do in order to mitigate the onset of a cramp...

Improve Physical Preparedness

Some authors propose a neuromuscular re-education of weak muscles - to me, this just means proper training. It’s my belief that poor training and recovery habits are of primary concern when it comes to EAMC. I’ve seen countless examples of players who are simply ill-prepared for the demands of elite tennis play. This DOES NOT simply mean that they are unfit. It could also mean that they are training too much. Why is it that many academy players, who train 5 hours a day, 6 days a week, experience cramping? Remember that to adapt, adequate recovery plans need to be in place - both from an active and passive perspective.

Electrical Stimulation

There’s some compelling research (Behringer et al 2016, 2017) that has found an increased CTF (cramp threshold frequency) for as long as 48 hours, when subjects were cramp-induced. Furthermore, when performed regularly (1-2 times per week), these subjects elicited nervous system adaptations that further improved the CTF (and perhaps could lead to favorable long-term adaptations).

Others (Khan and Burne 2007) found that when the achilles tendon was stimulated, ALL subjects reported a relief from cramps in the gastrocnemius. The majority won’t have access to this type of equipment but it does give further weight to the ‘altered neuromuscular control theory’ (i.e. that cramps are nervous system related).

Massage Therapy

Some authors propose that various massage techniques can alter neural excitability, effectively reducing the potential for cramping. Like most theories on massage therapy, they lack empirical evidence and objectivity (although many colleagues of mine have reported some benefits with pre-competition massage).

How My Match Ended and Final Comments

How I was able to extend that quarterfinal match to a tiebreak, I’ll never know. Perhaps it was the light stretching that helped ease the pain, or the perception that my sports drink was improving my hydration status. Maybe it was the diaphragmatic breathing I had learned in my last semester of undergrad that did the trick. Whatever it was, it helped...temporarily. In the end, there were too many drop shots to be chased down and wide balls to scramble for...my legs were simply out of commission.

Looking back, I’d probably have to admit to myself that I wasn’t fully prepared for that type of match. Neither of us were serving particularly well, but we were both relentless from the ground. And once muscular fatigue sets in (to that point), I’m not sure any amount of supplementation or acute strategies make an impactful difference. Sure they can help ease the pain - and I would advise to have contingency strategies in place nonetheless - but can players maintain the same level of intensity once a severe cramp manifests?

I believe it’s time to rethink the way in which we prepare players for tournaments. How many matches are to be played? What are the on-court conditions like? What surface are they playing on? Time of day? Etc., etc. All of these factors must be taken into consideration weeks and months before hitting a 3-4 week competitive block.

To this end, contributing EAMC to one specific factor - poor work capacity, weak muscles, a fatigued state, stress, inadequate nutrition - is short-sided. While I may not have been adequately prepared for a long match in the heat, I was still quite fit, even if I no longer competed regularly (perhaps that was part of the problem?!). But from what I’ve learned over the years, it’s rarely just ONE thing that contributes to pain, injury or some other sport-related ailment. It’s a combination of factors. The best we can do is educate ourselves, learn from our past experiences and prepare diligently for the future.

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