读报笔记：甜菜根成奥运会运动员秘密武器？

Call them pre-performance tweaks, athlete hacks, or just plain smart. In an effort to extrude every last bit of performance from their bodies, Olympians are likely to ingest some strange-sounding supplements in their final preparations for competition.

last bit of：最后一点……

Beetroot juice, bicarbonate of soda, and caffeine may sound like the ingredients for a particularly colorful science-fair project, but sports physiology experts say these competition-legal supplements may significantly improve an athlete's performance.

Beetroot juice：甜菜根汁

bicarbonate of soda：小苏打

"A one-percent difference in performance is something that will separate the guy who wins the 100 meter gold medal from the guy who comes last in the race," said Michael Gleeson, an exercise biochemist at Loughborough University in Leicestershire, U.K.

A one-percent difference in performance：百分之一的表现差异

exercise biochemist：运动生物化学家

Loughborough University：英国拉夫堡大学

Caffeine is one supplement that many non-athletes rely on every day. Although athletes' use was once subject to limits under antidoping rules, it is no longer a regulated substance. The athletes are seeking many of the same benefits that the rest of us gain from a cup of coffee.

rely on：依赖

antidoping rules：反兴奋剂规则

Beyond the benefits that most people recognize, such as increased alertness, "[Caffeine] also improves a lot of other physiological parameters, so a lot of people take it," said Keith Baar, an exercise physiologist at the University of California, Davis.

physiological parameters：生理参数

"There's no real reason why athletes wouldn't be taking caffeine," said Gleeson. "The dose that's needed to improve performance through a central brain stimulant effect is fairly low."

One limit to performance in many events that last longer than a minute, but usually less than 10, is the build-up of lactic acid in muscles. When intense exercise requires more energy than the body can provide through the aerobic process that uses oxygen, it creates energy using a different process, which ends with the formation of lactic acid. Buildup of this acid causes a burning sensation and can impair muscle contraction, slowing down athletes.

lactic acid：乳酸

aerobic process：好氧过程

a burning sensation：烧灼感

Some Olympians will take bicarbonate -- better known as baking soda -- to counteract this process. In theory, having a supply of bicarbonate in the blood allows it to buffer the acid's hydrogen ions, slowing down any buildup in the muscles, and helping to improve performance. 

hydrogen ions：氢离子

Bicarbonate is used by those athletes that can abide its often significant effects on the digestive system. Once it reaches the stomach, bicarbonate produces carbon dioxide, which can cause flatulence, bloating and other unpleasant, potentially performance-impairing side effects.

digestive system：消化系统

carbon dioxide：二氧化碳

Juicing a beet provides a deeply colored liquid rich in chemicals called nitrates, and promises to provide multiple sources of assistance to athletes, both physiological and psychological. Nitrates are also found in other vegetables such as Swiss chard and roots.

Studies have shown that beetroot juice alone can improve performance by 2-3 percent in events lasting 20-30 minutes, said Baar.