Coffee and slushies drinking and crowd effect on performance
Can drinking slushies boost my performance on hot days?
When you exercise in the heat, your core temperature rises until it hits a critical value—typically around 104°F (40°C) or a little lower—and you’re forced to stop. One way to delay this moment is to “precool” your body, an approach pioneered by Australian sports scientists. It was the Australians who showed up at the Atlanta Olympics in 1996 with form-fitting ice vests for their endurance athletes (which you can now buy for around $200), and they followed up at the 2004 Athens Olympics with ice baths for their athletes to plunge in immediately before competing.
Although these methods seem to work, they’re a little too unwieldy to become very widespread. But for the 2008 Olympics in Beijing, the Aussies unveiled a new secret weapon with truly mass-market appeal: the slushie. As Louise Burke, the head of sports nutrition at the Australian Institute of Sport, explained at a conference shortly after the games, ingesting a crushed-ice drink cools the athlete internally—not just with the frigid temperature, but due to the additional “phase change” energy required to melt the ice from solid to liquid.
In pre-Olympic tests, researchers found that the athletes lowered their internal temperature by more than 1°F by drinking the slushies, which consisted of 14 mL per kilogram of body weight of a half-and-half mix of sports drink and water. This translated into an advantage of about one minute in a 79-minute cycling time trial compared to controls. Plunging into a cold bath at 54°F (12°C) for 10 minutes cooled the cyclists even more—so much, in fact, that they started the time trial too fast and faded in the latter stages. That left the slushie as the best option.
Further research by scientists at Edith Cowan University in Western Australia, published in 2010, has confirmed the benefits of “ice slurries.” In this study, the subjects drank either a slushie at 30°F (-1°C) or cold water at 39°F (4°C). Thanks to the phase change energy, the slushie group decreased their rectal temperature by 1.19°F (0.66°C) and lasted 50.2 minutes in a cycle test to exhaustion in the heat, while the cold water group cooled by just 0.45°F (0.25°C) and lasted only 40.7 minutes.
Interestingly, the slushie group managed to keep biking until their core temperature reached 39.36°C, while the cold water group was forced to stop at 39.05°C—a small but significant difference. The researchers speculate that the subjects may have cooled their brains slightly as the slushies passed through their mouth and throat. Since the decision to terminate exercise in the heat is thought to be controlled centrally, a cooler brain may have permitted the rest of the body to get a little hotter than usual before calling a halt. Earlier studies with dogs and goats have suggested that brain temperature, rather than core temperature, might control the limit of exercise tolerance in the heat.
The performance boost offered by slushies, ultimately, is a few percent at most. But it’s a simple intervention that could easily be implemented at big sporting events—far more easily than ice baths, and far more cheaply than cooling vests. That’s one reason the Australians brought seven slushie machines to Beijing and used them for soccer, track, cycling, triathlon, rowing, field hockey, and several other sports. The other reason is familiar to every athlete looking for a slight edge wherever he or she can find it: the mental boost. “In Beijing, we wanted something new,” Burke admitted. “You always have to have something new for athletes for that placebo effect.”
Will drinking coffee help or hinder my performance?
Until 2004, Olympic athletes could test positive for caffeine if they drank as few as three cups of strong coffee. Then, frustrated with trying to regulate such a commonly used substance, the World Anti-Doping Agency (WADA) removed caffeine from its list of restricted substances—and the strangest thing happened. After the ban was lifted, caffeine levels found in WADA urine tests actually decreased in almost all sports. If it wasn’t worth banning, athletes apparently figured, it wasn’t worth taking.
They were wrong.
“I don’t think there’s any doubt that caffeine is a very powerful ergogenic [performance enhancing] aid,” says University of Guelph professor Terry Graham, one of the world’s leading researchers on the topic. “It’s probably the most versatile aid out there.” After decades of studies, it’s now well established that caffeine helps sprint performance and improves endurance in activities lasting up to two hours. There’s also increasingly solid evidence that it helps resistance exercise like weightlifting.
The usual counterargument is that caffeine’s diuretic effect can leave you dehydrated, ultimately hurting performance, particularly in endurance events. But recent research has thoroughly dispelled that notion, Graham says. Another commonly repeated myth that has now been disproved is that caffeine’s performance boost results from the body burning more fat for energy, he says.
How caffeine does work is still up for debate. Caffeine is a stimulant, and it may also carry a placebo effect for some athletes—but that’s not the whole story either. “If I were to place electrodes on your muscle, and start to stimulate it so that your muscle is contracting and your brain’s not involved, I can still see an effect [from the caffeine],” Graham says. The current theory is that caffeine directly affects how muscle fibers contract at a cellular level, making each fiber contract more strongly when it receives a signal from the nervous system.
Caffeine, however, is not the same thing as coffee. The only rigorous study directly comparing the effects of caffeine (in pill form) with coffee was performed in Graham’s lab. Surprisingly, he and his colleagues found that only pure caffeine produced a performance boost, even when the level of caffeine in the bloodstream from coffee was identical.
“We didn’t believe it at first, so we kept adding subjects,” he says, “but the data just got stronger.” Other studies have found a performance-enhancing effect from coffee, so Graham is cautious about overstating his results. What is clear is that the effects of coffee, with its complex mix of bioactive ingredients, are far harder to nail down than the unambiguous effects of pure caffeine.
Current estimates suggest that somewhere between 82 and 92 percent of North American adults consume coffee on a regular basis. The use of caffeine explicitly for its performance-enhancing qualities is also widespread: a British study published in 2008 found that 60 percent of cyclists and 33 percent of track and field athletes took caffeine to enhance athletic performance. International-caliber track athletes were twice as likely to seek a boost from caffeine as club-level athletes.
But Graham sounds a note of caution about the value of a caffeine-fueled personal best for recreational athletes, who are typically focused on beating their own best performances rather than beating specific competitors. In effect, it simply moves the finish line closer. So despite all his research, Graham has never used caffeine in 20 years of running marathons.
Does competing in front of a crowd improve performance?
One of the unique aspects of running is that ordinary weekend warriors have the opportunity to toe the starting line right next to the fastest runners in the world and run through the streets of big cities with thousands of spectators cheering them on.
In fact, some major races like the Marine Corps Marathon in Washington, D.C., draw big crowds of spectators without any elite runners at all. Not surprisingly, many runners aim to set their personal best times at these races, reasoning that the energy of the crowd will help propel them forward. But does it really make a difference?
Researchers have been studying the effect of spectators on sports performance for years, in an attempt to understand the well-known “home advantage” experienced by professional sports teams. This effect is thought to stem from a wide variety of factors such as biased officials, travel-weary opponents, and elevated testosterone in home-team players eager to protect their home turf. While you’d think the crowd would be a key part of home advantage, a surprising study published in 2010 by Niels van de Ven of Tilburg University in the Netherlands shows that this isn’t necessarily the case.
Van de Ven took advantage of two quirks of the schedules of Italian soccer leagues during the 2006–2007 seasons. First, he examined 20 games that were played in empty stadiums, since the home teams were being penalized for misbehaving fans and safety infractions. After carefully controlling for the quality of the teams, he found that the same home advantage existed with or without a crowd.
Second, he examined games between teams that shared the same home stadium, like AC Milan and Internazionale or AS Roma and Lazio Roma. In these cases, the home team has dominant crowd support because of the presence of its season-ticket holders. However, no home advantage could be detected in these games, suggesting that home advantage (in soccer, at least) likely results from familiarity with the stadium rather than from loud cheering.
This doesn’t mean that you won’t get a performance boost from lining up at a big race—but it suggests that the encouraging shouts from friends, family, and complete strangers aren’t the crucial factor. Instead, it’s the adrenaline-producing stress and anxiety of participating in a big event that harnesses your fight-or-flight instincts and allows you to exceed your usual abilities. “For your local marathon, you will not be as pumped up as for the Boston Marathon,” van de Ven says.
But there’s a trade-off, as the study suggests: if you run your local marathon, you’ll not only benefit from sleeping in your own bed and avoiding travel, but you may also be able to train on the course to become familiar with it. The best choice may depend on your personality: if you’re usually anxious before races, the local race may be your best bet; if you need help getting psyched up, taking a trip to a big event could give you a boost.