Question

Did you know that sixty percent of your body weight is water？However，a loss of only two percent of this water through dehydration(脫水) during exercise can significantly affect your performance. The more you sweat，the more your exercise performance declines，unless you drink enough to replace your loss of fluids.

When you lose too much water，you can overheat quite easily，especially in a warm environment. But this is not the only problem you may be faced with. Dehydration leads to your heart pumping much faster，which means exercise becomes more difficult and requires more effort. Despite these problems，however，many of us simply do not take enough fluids in when we head for the gym or set out on a run.

So why is this? How do we manage to lose so much water without simply drinking more to replace it？Well，it is easier than you think. When we are at rest，we quickly become aware that we are thirsty and will put that right by having a drink. When we exercise，on the other hand，our thirst mechanism(結(jié)構(gòu)) does not work as effectively，so we don't notice early enough that we are actually thirsty. In fact，we only start to feel thirsty when we have already lost around two percent of our body weight.

Another problem is that，the more dehydrated we become during exercise，the more difficult it is to prevent further dehydration—because our stomachs become intolerant to fluids and we do not absorb water properly，just when we need it most.

The key thing about fluids and exercise is to manage your intake properly—regular small amounts are better，and some should be drunk before the period of exercise begins. You also need to match your intake to the sort of exercise you are doing. For instance，for one hour of exercise，such as taking part in a 10 km run，you need to drink about two extra liters of water. For longer periods of exercise，sports drinks are recommended.

1.We know from the text that during exercise，dehydration________.

A. can be easily avoided

B. will lead to poor performance

C. can cause many health problems

D. will be controlled whenever we drink again

2.Why do people suffer from dehydration easily during exercise?

A. Their thirst mechanism stops working.

B. Their focus is on the exercise.

C. Their thirst response is slow.

D. Their stomachs are full.

3.When exercising，you are advised to________.

A. have regular breaks

B. drink water accordingly

C. drink sports water in advance

D. have at least two liters of water

4.What would be the best title for the text?

A. Keep fit

B. Say no to sports!

C. Time to get drinking!

D. Ways to avoid dehydration

Answer 1