Melting in Melbourne: Thoughts on the heat

16 Jan 2014 Posted by

Insane.  Inhumane.  Not healthy.  Brutal.  Life-threatening.  Insert your adjective here, but these are some of the responses to the first two rounds of the Australian Open in Melbourne, where extreme heat has dominated the headlines.  Finally, on the fourth day, the organizers decided to suspend play on the uncovered courts until temperatures dropped (and then it rained, ironically), but not before a few players collapsed during matches, and the world’s media fed heat-related hype.

Below are four of my thoughts on the heat and the Australian Open’s handling of it so far.

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1. It’s foolish to deny the obvious

Water bottles have melted to the court surface.  Athletes and ball-kids have both passed out mid-match.  Players have hallucinated.  A camera-man fried two eggs court-side.  It has been incredibly hot in Melbourne, and I sure wouldn’t want to play in those conditions.  Temperatures have risen beyond 40 Celsius (105 F), which would be even hotter in direct sunlight and the heat-trapping confines of a tennis stadium.  To tell players to “deal with it” would be to trivialize the challenge of playing in the heat.  And really, even if the medical risk were non-existent, the impact of heat on play is large enough to reconsider whether the game suffers as a result.

The medical risk is however not zero, although the risks have been overhyped by the media in response to players’ understandable frustration, anger and at times, bewilderment.  What doesn’t help is when there is an apparent denial of a real problem.

For instance, consider the following quote by the tournament doctor:

“Tennis, as a sport, is relatively low risk for major heat problems compared to continuous running events. So you’re more likely to get into trouble in these events, in a 10K road race, than you are in a tennis match. As you can appreciate, the players, the time the ball is in play, in total time for the match is relatively small. The amount of heat they produce from muscles exercising is relatively small in terms of what someone continuously exercising will do. They sit down every five to ten minutes for every 90 seconds at change of ends, so there is chance to lose some heat at that time. Tennis by and large is a low risk sport, and that’s why by and large, like cricket, we can play in these conditions and not be too concerned.”

That’s not quite true.  There are papers documenting the body temperature of tennis players during match-play and they show that body temperatures rise to around 39 Celsius (normal is 37C) during shorter matches in mild conditions.  That’s not dissimilar to what most people will reach during a half-marathon.  Elite runners get hotter, but a five-set tennis match, in very hot conditions, would naturally impose an even greater challenge on players, and so to suggest that the sport is low risk is a slight cherry-picking of the evidence.

The intermittent activity of tennis is certainly different to that of running a 10km race, but the possibility of driving body temperature up through high intensity sprint exercise has been well-documented – in fact, one of the most effective ways to overheat is to sprint repeatedly with short recoveries.  Sustained exercise is often too low in intensity to be dangerous, and when high intensity activity periods happen at 45C, however shorter, there is a very real risk.

Further, the doctor is missing the point, because this is not a debate about tennis, but rather about the conditions PLUS the sport.  Tennis may be a low-risk sport, but 45C would increase the risk of doing nothing!  Even spectators and ball-kids have been collapsing – sitting down is “risky” when it’s that hot with insufficient opportunities for cooling.  I guess it all depends how you define risk.

On that note, the doctor talks about the “risk for major heat problems”, but why make major problems your criteria to act?  That’s a tap-dance approach fit for a politician, because you can define “major heat problems” as death (see point 2 below) and then pretend everything is peachy because nobody is dead.  Meanwhile, the “minor heat problems”, like players collapsing and hallucinating with dizzy spells can be overlooked – they’re minor, right?

Ultimately, the tournament organizers have adopted an approach that actual events are exposing as indefensible.  One player collapses, fine – you can write that off as an aberration, a player with a virus or adverse reaction to the heat.  When it happens to two, three, four players, and when ball-boys and cameramen are joining the ‘fun’, then you kind of have to acknowledge that there is a problem.  You may not want to call it a “major risk” out of fear of litigation, but it’s clearly an issue, so stop denying it.

Right now, all that is happening is that a layer of bad press about the handling of the issue is being added to the problem of scheduling around the weather (which organizers can’t control).  Rather make clear, transparent decisions, acknowledge the obvious (if not the major risk), and let the focus switch back to performances, not physiology of the heat.

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2.  Heat – heatstroke is the ultimate, major risk, but there are other challenges that precede it

Now, having said that, I do want to give the doctor something of a reprieve on that “major risk” issue, because I want to clarify some issue about the physiology of exercise in the heat and try to downplay some of the hype coming out of Melbourne.  Bear with me – this may seem academic, but some basic physiological principles have to be understood in order to understand the Australian Open events this week.

The greatest risk in the heat is heatstroke, when the body temperature is raised to harmful levels.  As you are reading this, your body temperature is around 37C, and it’s normal during exercise for it to rise to between 39 and 40C.  Once it hits 40, there is evidence that the brain reduces recruitment of muscle and volitional fatigue happens soon after.  When people are made to run on treadmills in lab studies, exhaustion happens when this body temperature is reached.  Think of it as a short circuit switch, for your own protection – the hot brain reduces muscle activation once we hit 40C, and there is also evidence that this reduction in muscle activation happens in anticipation of the thermal failure, specifically to prevent it.

Highly motivated athletes, in race situations, can probably go higher than this, but not by much and probably not for too long.  In some cases, however, the body temperature overshoots this ‘glass ceiling’, and then you have a medical emergency, or the “major risk” being spoken of.  I attended a talk by Doug Casa in London last year, and he gave some stats on how often this happens.  It’s pretty varied, because conditions, fitness, climate, race distance all affect the risk, but it is pretty rare, ranging between 1 in 2000 and 1 in 10,000.  For example, in the Two Oceans Marathon in SA, there’ve been two cases in six years, out of around 120,000 people.  But that’s a cool race, and the intensity is low because it’s long distance.  In the Falmouth Road race, the prevalence is a lot higher – 1 in 2000, but it’s a hot, short, high-intensity race.

There’s also some evidence that heatstroke happens as a result of some kind of pathology, and I was a co-author on this paper which documented cases of heatstroke that could only happen if there was a total failure of normal physiology, so the heatstroke picture is a lot more murky than the simplistic idea that if you play sport in the heat, you are in mortal danger of death from overheating.  This is the fear which has been hyped up in Australia, and I suspect it is the smallest risk (though with the greatest implications, admittedly) faced by the players in Melbourne.

So to clarify this point – in the heat, heatstroke may be the ultimate, most severe risk, but it is preceded by a host of other challenges which I suspect are more relevant for understanding what we’ve seen this week so far.  I want to downplay some of the fears around the heat in Melbourne, but emphasize the challenges that still exist.  We should not be too quick to embrace the apocalyptic terror about playing sport in the heat, but we should recognize the need for pragmatism to tackle and overcome the “lower risk” challenges.

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3. Challenges in the heat

For tennis, the risk of driving body temperatures towards the 40C limit is very real when matches are played at 40C or higher.  Even with moderate humidity, it becomes impossible to lose heat to the environment, and the body temperature will rise.  We call this an “uncompensable environment”.

But heatstroke is a level beyond what happens in normal cases.  Think for instance of why a ball-boy collapses even though he is not generating much heat through sport?  Why have spectators fainted?  And what causes the dizziness and the loss of co-ordination experienced by players as they begin to succumb to the heat?  Why do they feel so terrible and take hours to recover after matches?  These are not heatstroke cases, but rather a mix of blood pressure problems and the body’s normal response to a body temperature approaching (but not exceeding) potentially harmful levels.

Regarding blood pressure, you’re probably all familiar with cases of people who have fainted during ceremonies.  You see it often when soldiers are on parade.  What is happening there is that the body, in an attempt to lose heat, is sending blood to the skin, but because the person is standing still, there is insufficient pumping of the blood from the legs and periphery back to the heart, and the blood pressure falls.  The same happens when runners cross the finish line of races, and don’t keep moving.  Blood pools in the veins, it’s already in the skin circulation because of the heat, and the body is left with one last resort – faint in order to keep the blood pressure up.

The dizziness and loss of co-ordination is symptomatic of the body temperature heading up towards that 40C mark.  This is likely scant consolation to those players who have experienced it – they don’t care whether they’re on the verge of heatstroke or whether they’re still “safe” but feeling like death, but the reality is that they’re not really in danger at this point, just having a really, really bad day out.

This is not quite the same as saying it’s all mental, or an issue of mind over matter (I hate that cliche), because the physiological challenge of coping with feeling hot is very real.  But what the research has shown is that when body temperature is between 38 and 40 degrees, as it almost always is during exercise, the perception of thermal strain and comfort is key to performance.  So far, the dramatic events of Melbourne, the extreme cases, have highlighted what happens when the perception of thermal strain becomes too great to bear, but it’s a drama being played out despite “normal” temperatures.  The key issue is managing the physiology near that ‘failure’, not beyond it.

Now, this may appear to be a semantic issue, I admit, but it’s one worth paying attention to, because if the issue is that the physiology is trying to protect the body, rather than ‘failing hopelessly’, then it means there may be strategies that can be adopted to help keep the player functioning despite being uncomfortably hot.

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4. Let’s get pragmatic – some suggested strategies to minimize the effect of heat

In that regard, some final thoughts on what strategies should be adopted.  The main strategy determining the outcome in the heat happens weeks before the first ball is even hit – heat acclimitisation.  If you’re a player going to Australia and you don’t prepare for hot conditions, then you cannot have expectations of doing well there.  You also cannot complain about the heat if you haven’t at least tried to prepare for it, and I suspect this is the biggest differentiator in the response of different players to the conditions.  Studies have shown that endurance capacity more than doubles within about a week of exposure to the heat.  Runners made it 23 minutes before they were exhausted on day 1 in the heat, but can complete an hour by Day 7.  The human capacity for coping with the heat is enormous, but it must be trained.  That box, if unticked, makes everything else largely irrelevant.

In addition to this, there are a few ‘in-match’ strategies worth considering.

Until today’s decision to suspend play, the organizers had enacted a clause that allowed a 10-min break between the second and third sets of women’s matches.  This break is literally a “cooling time-out”, and there is evidence showing that it is effective in helping reduce the body temperature.

There are some problems with implementation though.  First, why it applies only to women’s matches beats me.  There is no physiological basis for suggesting that men are more immune to the heat than women, and so it should be used for both draws, not just one.  If anything, the men have a size disadvantage in the heat, and might require the break.  Also, there’s a small matter of two additional sets in the longest men’s matches.  That’s a crazy distinction.

Second, the logic behind it is sound, because it gives players a break from exercise and the direct sun (which would reduce their temperatures), and also a chance to actively cool themselves using ice vests or ice-packs, as you’ve no doubt seen them doing on change-overs.  My contention is that they should do these breaks more often, but could probably make them slightly shorter.

For instance, why not allow a three minute change-over every time new balls are called for?  Or after every six games, designed to allow a break at approximately half-way through a set?  This is slightly longer than the current change after odd-games, and would allow slightly more effective cooling, more often.  A five minute break after each set would also help, with 10 minutes before the final set (set 3 for women, set 5 for men).  People will argue that this changes the match too much, but the reality is that the fans will benefit from the break as well, and the match is being changed by the heat anyway.  Rallies are known to be shorter in the heat, as players go for shots to avoid protracted rallies, and also choose to chase down fewer balls.  And besides, would you rather watch a thermally-induced 6-0, 6-1 capitulation, or a competitive match with longer breaks?

Also, they could place large fans at the back of the court – players are always walking there between points anyway, and if the fan is able to provide cooling for even 15 seconds after every point, that would make a significant difference to a player’s thermal comfort (try it at the gym and feel how big an effect the fan has on how you feel).  The fans could be placed in the back left and right corner facing parallel to the baseline so that they wouldn’t affect the play, or they could be switched on immediately when the point is completed.

Fans on the players during changeovers is also an obvious strategy, especially if they player is going to wet themselves with water and apply ice.  It would accelerate cooling and help reduce the thermal strain, and wouldn’t affect the match either.  The name of the game in the heat is to take every action to avoid it, and if you can’t avoid it, then minimize it proactively.  Eight seconds exposure, 30 seconds recovery would be the formula.

The point is, the policy and the debate it currently inspires is too extreme – it’s a player vs officials opinion-match consisting of: “We’re going to die, you’re inhumane”, vs “Just play and stop complaining, there’s no risk”.

It seems pretty obvious to me that there is ‘risk’, however you wish to define it.  At worst, it is the risk of heatstroke, though I think in tennis, this will be exceedingly rare.  But can anyone sincerely argue that players collapsing, retiring and surrendering matches with a physiologically-induced ‘whimper’ is not worthy of being treated as a “risk”, demanding intervention?  There are many risks in the heat and many can be offset with strategies to help deal with issues of thermal comfort (the largest culprit) and elevated, but not dangerous, body temperatures.

Some middle ground would be nice.  So will the cooler weather forecast to hit Melbourne over the weekend, which will render this discussion a distant memory, until 2015, when it’s almost certain to happen again.  It’s the “happy slam”, until it becomes the hellish one.

Ross

 

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