We all know the obvious physical effects of high-intensity sport; sweat pouring, heart thundering, adrenaline spiking, nervous energy sending those rogue spasms through your limbs, the desperation to win sitting heavy on your shoulders.
Honestly, it can get so bad you almost spill your popcorn.
Because yes, we’re sure playing professional sport is plenty exhilarating, but for scores of sport-mad Australians, watching it can be every bit as physical.
And it is shaping up as a truly golden year for world sport, headlined by the FIFA World Cup that will kick off in Russia in mid-June; a nail-biting month of football that will have living rooms across the country shaking like the corner flag after a Tim Cahill goal celebration every time the Socceroos take to the pitch. (But if you think you're excited, imagine how the Kia Australian Match Ball Carrier, chosen to deliver the ball to the pitch for the Socceroos first game against France - is feeling?)
It's just a game? Yeah, right. A recent study in Montreal tracked the heart rates of ice hockey spectators - a collection of body-painting lunatics who make your average cult member seem a little half-hearted by comparison - and found that just watching an exciting match on television from your couch could increase your heart rate by as much as 75 per cent.
That’s a lot; roughly equivalent to what the researchers describe as “moderate exertion”. In other words, our hearts are thumping like we're taking a brisk walk even as we sit still on the couch.
Watching a game live had even more staggering results, with heart rates jumping by up to 110 per cent in the clutch moments - or the same as when you undertake “vigorous exertion" - along with increased perspiration and even a suspected spike in blood pressure.
The physical effects can be so enormous that a German study of local football fans found that a stressful match could increase the the risk of a heart attack or stroke by 200 per cent. Which is something to keep in mind next time you scream at the TV that your footy team is “going to give me a heart attack”.
"Of prime importance for triggering a stress-induced event is not the outcome of a game - a win or a loss - but rather the intense strain and excitement experienced during the viewing of a dramatic match, such as one with a penalty shoot-out," the report reads.
Of course, no amount of watching sport can match the intensity of, say, Rafael Nadal doing battle at the French Open, a Grand Slam he is currently attempting to conquer for an incredible 11th time. In fact, the current world number one can run as far as 23km from the opening round to a high-pressure final.
And we're not talking a slow jog, either; it's all in short, sharp, joint-burning sprints that would have his heart thumping like a high-magnitude earthquake. Really, who needs that kind of pressure?
The question, of course, is why? Why are we all so emotionally invested (significantly more so than we are in our careers or our social circles, according to some experts) in whether a stranger swings a tennis racquet, kicks a football or tosses a dart better than another stranger?
At least part of the answer is our innate need to feel the heady rush of adrenaline. As humans, we want it. And the players have got it. And amazingly, just by watching them play, we can share it.
Adrenaline, like dopamine or endorphins, is addictive. It’s why people jump out of planes, launch off ski jumps, dive with sharks or partake in any number of seemingly insane activities in the interests of apparent fun - the excitement forces the brain to release these happy chemicals.
The best part? You don’t actually have to do these impossible tasks, just imagining them - or watching someone else do them - can be enough to get your adrenaline pumping.
It’s the same reason we are so in love with staggeringly fast performance cars, like Kia’s new Stinger. We know the cold reality; that 95 per cent of all our driving will be at the posted speed limit - or, if you live in one of our more congested capitals, well below it. But the mere fact we could, if we wanted to, unleash its performance on a racetrack or twisting mountain road is enough to get our hearts beating faster, even as we trudge through the sludge of peak hour.
“When there is an intense game or intense play some fans have a very emotional response — a fight-or-flight response with an increase in the sympathetic nervous system output and an increase in adrenaline levels,” confirms Dr. Robert Kloner, a director of cardiovascular research at Huntington Medical Research.
When watching sport, experts say, our brains fool us into thinking we’re playing, too. And not just in the way that we refer to the team as a “we”, like “we’re really going to have to toughen up in defence if we’re any chance of winning this”. It's more that, on a subconscious level, our brain actually thinks we’re on the field and playing. It’s a feeling described as the “in their shoes” phenomenon.
“This phenomenon allows a feeling of connection, and community without verbal communication or the need to directly talk to the pro athlete who just won the World Series with a grand slam,” says clinical director of the Helix Healthcare Group, Dr. Jesse Hanson.
It’s why we feel so elated when our team wins, and so deflated when they lose; on some level, it’s like we’ve played the game, and their results are ours, too. And again, this is a physical, rather than imagined, reaction. Studies show that after a team victory, dopamine and testosterone levels spike for hours afterward.
Hell, things even taste better. A study by Cornell University that forced fans to blind-taste sorbet after matches found identical foods taste sweeter after a victory, and more sour after a loss. All of which means your favourite team losing can leave a literal bitter taste in your mouth.
One word of warning, though; viewing sport isn’t exactly the same as playing sport. You won’t actually lose weight or get any fitter watching other people run around, just in case you were hoping to trade your gym membership for tickets to the Australian Open.
“Watching a game is not a substitute for physical activity,” confirms the Canadian study’s lead researcher, Professor Paul Khairy. “It raises heart rate (and likely also increases blood pressure) but it does not carry the same benefits for cardiovascular health as exercise.”
So the next time you're berating a player from the sideline or your couch, maybe go a tiny bit easier on them. Remember, your brain thinks it's actually you out there. So you'll really be going easy on yourself.