4 sentences for 热身 (rè​shēn — warm up)

1. 游泳前不做热身运动，腿部很容易抽筋。

   yóu​yǒng qián bù zuò rè​shēn yùn​dòng, tuǐ​bù hěn róng​yì chōu​jīn.

   If you don't warm up before swimming, your legs can easily cramp.

   Source: Dong Chinese Dictionary

2. 游泳前不做热身运动容易导致小腿痉挛。

   yóu​yǒng qián bù zuò rè​shēn yùn​dòng róng​yì dǎo​zhì xiǎo​tuǐ jìng​luán.

   Failing to warm up before swimming can easily lead to calf cramps.

   Source: Dong Chinese Dictionary

3. 他在运动前先做了一些伸展运动来热身。

   tā zài yùn​dòng qián xiān zuò le yī​xiē shēn​zhǎn yùn​dòng lái rè​shēn.

   He did some stretching exercises to warm up before his workout.

   Source: Dong Chinese Dictionary

4. 运动员在比赛开始前通常需要进行充分的热身。

   yùn​dòng​yuán zài bǐ​sài kāi​shǐ qián tōng​cháng xū​yào jìn​xíng chōng​fèn de rè​shēn.

   Athletes usually need to do a thorough warm-up before a game starts.

   Source: Dong Chinese Dictionary