往年六到九月中騎單車總是頂著豔陽，一路不斷補充水分，雖然通常選擇有遮蔭的路線，或是親水的路線，但是燠熱的天氣總是令人難受。（今年因為受傷，休息的大半年，所以沒經歷這種苦。）一直要到十月的第二周，台北才會開始轉涼，也就是進入了一個愉快的單車季節了，或是任何陸上運動的好季節。
天氣一轉涼，總是覺得好像體力好了許多，騎起單車也變得犀利起來。這個奧勒岡大學的研究證實了心中的猜想：溽暑的訓練提升了在秋涼後的運動表現。
November 3, 2010, 12:01 am
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Can training for hot weather help you to perform better when thetemperature outside begins to drop? That question, the answer to whichintuitively would seem to be a resounding no, became the inspirationfor a new study by scientists at the human physiology department at the University of Oregon.For the study, published last month in The Journal of AppliedPhysiology, researchers recruited 20 highly trained competitivecyclists from the university’s cycling team and local cycling clubs andput them through a series of laboratory performance tests, including atime trial, under both hot and cool conditions.
The riders were divided into two groups. One set began heatacclimation. This is a fairly straightforward process. You ride in theheat; your body adjusts. In this case, the riders completed 10 trainingsessions in a lab heated to 104 degrees. The room was roasting. Thecycling itself was easy; the intensity hovering at around 50 percent ofeach rider’s VO2 max or maximal oxygen consumption, a leisurely pacefor a trained athlete. The riders pedaled for 45 minutes, rested for 10minutes, then rode for another 45 minutes during each session. Thisacclimation riding was in addition to their usual training mileage.
A second set of riders, meanwhile, acting as a control group,completed the same training but in a cooled laboratory, so that theywould not become heat acclimated.
Afterward, each rider repeated the laboratory performance tests fromearlier, to see how they now compared. The laboratory in which theyrode during the cool sessions was chilled to an autumnal 55 degrees.The results were striking.
The cyclists who were heat acclimated performed anywhere from 4 to 8percent better than they had before they trained in the heat, while thecontrol group did not improve at all. “That’s a huge difference whenyou’re talking about competitive performance,” said Santiago Lorenzo,the lead author of the study and now a postdoctoral research fellow atthe Institute for Exercise and Environmental Medicine at Texas HealthPresbyterian Hospital in Dallas. He also competed in the 2004 Olympicsin Athens as a decathlete.
“We were surprised,” he continued, and not just that heatacclimation should have any positive effect on the riders’performances, “but by the magnitude and consistency of that performancebenefit. It was really quite dramatic.”
It’s common knowledge (backed by decades of sound scientificresearch) that to perform well and safely in hot weather you need to beacclimated to working out when it’s hot. “Humans’ ability to adapt toheat is one of the most robust adaptations that we have,” saidChristopher Minson, head of the department of human physiology at theUniversity of Oregon and senior author of the study. As a result of ourgetting used to the heat, the volume of plasma in the blood increases,sweating begins earlier and is much heavier, and the heart adapts,pumping blood to the skin’s surface faster, thereby releasing heatthrough convection cooling. All of these adaptations allow the body’score temperature to remain within a physiologically safe range.
convection n. the process in which heat moves through a gas or a liquid as the hotter part rises and the cooler, heavier part sinks （熱通過氣體或液體的）運流，對流
But why would heat adaptations affect exercise performance in coolweather? “That’s a very good question,” Dr. Lorenzo said, for which theresearchers don’t as yet have a definitive answer. “It’s likely thateven in cool temperatures,” like those in the 55-degree lab,” Dr.Lorenzo said, “athletes become overheated during intense exercise andso heat adaptations have an impact.”
The adaptations, in and of themselves, also may improve performance,Dr. Minson said. “We saw significant cardiovascular adaptations,” hesaid, which might confer benefits to athletes, no matter what thetemperature in which they’re training or racing.
But there are many caveats to the study that should be consideredbefore you head to Death Valley or rush out to turn up the thermostatin your local gym. “We were dealing with highly trained athletes in avery tightly controlled environment” Dr. Lorenzo said. “This was not areal-world-type situation.” Whether the same benefits would accrueduring a recreationally paced century bike ride in mid-November is notknown.
caveat n. a warning that particular things need to be considered before something can be done 警告；告誡
Similarly, the researchers were examining heat acclimation in coolbut not bone-chilling temperatures. “Working out in really cold,wintertime temperatures might be a completely different ballgame,” Dr.Lorenzo said, during which previous acclimation to the heat might haveno impact or worse.
Finally, the researchers dealt only with cyclists. “My best guesswould be that the findings would apply equally to competitive runnersand other endurance athletes,” Dr. Minson said, “but we don’t know thatfor sure.” He noted that running and cycling are quite differentphysiologically — which hasn’t stopped some eager marathoners and otherathletes from contacting him, asking whether they can improve theirfall-season race times by donning plastic garbage bags or ready-madethermal suits “to make them really hot” during training runs. He tellsthem that he simply doesn’t know enough yet to respond to theirquestions but hopes to pursue more experiments in this area and havemore complete answers eventually.
In the meantime, if you do decide to put these preliminary findingsto work in your fall training, Dr. Lorenzo said, be sure to undertakethe desired heat adaptations gradually, over multiple slow, easysessions. Don’t rush or overdo the acclimation process. Overheating canbe dangerous (which is why heat acclimation exists, of course). If youbegin to feel ill during any of the acclimation sessions, slow down orstop. Consult your doctor. And if you are willing to take the aestheticsensibilities of your neighbors into consideration, do not wear a trashbag.
http://well.blogs.nytimes.com/2010/11/03/phys-ed-will-training-in-the-heat-improve-your-performance/
The story was taken from the website of The New York Times, which is not involved with nor endorses the production of this blog. The copyright remains with its original owner.
