Hãy khởi động rồi kéo giãn cơ thể.

Hãy marks the sentence as an instruction, suggestion, or gentle command. It is often used in written instructions, exercises, announcements, or formal speech.

So Hãy khởi động rồi kéo giãn cơ thể means something like:

• Warm up, then stretch your body
• Please warm up and then stretch

Compared with English, hãy does not have one perfect translation. Depending on context, it can feel like:

• please
• do
• an instruction marker with no direct English equivalent

In everyday casual speech, Vietnamese speakers often leave hãy out and just say:

• Khởi động rồi kéo giãn cơ thể.

That still sounds natural.

Vietnamese often omits the subject when it is obvious from context. In an instruction like this, the listener already understands that the speaker is telling you what to do.

So:

• Hãy khởi động rồi kéo giãn cơ thể.

naturally means:

• You should warm up and then stretch your body.

Vietnamese does this much more often than English. In commands, recipes, signs, and instructions, leaving out the subject is completely normal.

Here rồi means then / after that, linking two actions in sequence.

So the structure is:

• khởi động = warm up
• rồi = then
• kéo giãn cơ thể = stretch the body

This tells you the order:

1. warm up
2. then stretch

In other contexts, rồi can also mean already, but that is not what it means here.

For example:

• Tôi ăn rồi. = I already ate.

So rồi has more than one use, and context tells you which meaning is intended.

In this sentence, khởi động means to warm up, especially before exercise.

The verb khởi động can also mean to start up or to activate in other contexts, such as machines, programs, or activities. But with fitness or physical movement, it commonly means warm up.

Examples:

• Khởi động trước khi chạy. = Warm up before running.
• Khởi động xe. = Start the vehicle.

So this is a good example of a word whose meaning depends on context.

Literally, it means stretch the body.

Breakdown:

• kéo = pull
• giãn = stretch / extend / loosen
• cơ thể = body

Together, kéo giãn means to stretch out. In exercise language, kéo giãn cơ thể means to stretch your body.

In natural English, we often just say stretch rather than stretch your body, but Vietnamese often states cơ thể explicitly.

Vietnamese can be more explicit in places where English is often shorter. Saying kéo giãn cơ thể is perfectly natural and emphasizes the body as the thing being stretched.

English speakers may feel that stretch your body sounds slightly redundant, because in English we usually just say:

• stretch
• do some stretching

But in Vietnamese, adding cơ thể is normal and clear.

You may also hear related expressions like:

• kéo giãn cơ = stretch the muscles
• duỗi người = stretch oneself / stretch your body out

In this sentence, kéo giãn works together as a verb phrase meaning to stretch.

Although:

• kéo by itself means pull
• giãn by itself means expand / loosen / stretch

together they form a more specific exercise-related action: stretch out.

This is common in Vietnamese. Two elements can combine into one natural action phrase, and the whole phrase should be learned together.

Yes, it is natural, especially in instructional or health-related contexts.

It sounds like something you might hear:

• in a workout video
• in a PE class
• in written health advice
• in a fitness app

That said, there are other natural ways to say something similar, for example:

• Hãy khởi động rồi giãn cơ.
• Khởi động trước, rồi kéo giãn cơ thể.
• Hãy làm nóng người rồi kéo giãn cơ thể.

These are slightly different in style, but the original sentence is perfectly normal.

Both can relate to warming up, but they are not exactly the same in tone.

• khởi động = warm up, usually in an exercise or sports sense
• làm nóng người = literally make the body warm, which also means warm up, but can feel a little more descriptive

In sports, fitness, and instruction language, khởi động is especially common and standard.

So in this sentence, khởi động is a very good choice.

You could, but the meaning would be slightly different.

• và = and
• rồi = then / and then

If you say:

• Hãy khởi động và kéo giãn cơ thể.

it means Warm up and stretch your body.

That is fine, but rồi more clearly shows sequence: first warm up, then stretch.

Since warming up usually comes before stretching in a routine, rồi is very appropriate here.

Cơ thể is a standard and natural word for body. It is common in health, anatomy, fitness, and everyday speech.

Other possibilities exist, but they are not always interchangeable:

• người = body / person / oneself, depending on context
• thân thể = body, a bit more formal or literary in some contexts
• cơ = muscle, not body

So cơ thể is a very safe and natural choice here.

For example:

• kéo giãn cơ thể = stretch the body
• làm nóng người = warm up the body / warm yourself up

Notice that Vietnamese may choose different body-related words depending on the expression.

A rough pronunciation guide is:

• Hãy ≈ like high with a glottal, dipping-rising tone
• khởi động ≈ khoy dohng
• rồi ≈ zoy in northern speech, often closer to yoy in southern speech
• kéo giãn ≈ keo zan or keo yang depending on accent
• cơ thể ≈ guh thay or kuh thay, depending on how you approximate it

A natural rhythm would be:

• Hãy khởi động / rồi kéo giãn cơ thể.

with a slight pause after khởi động.

The sentence flows as two linked commands:

1. Hãy khởi động
2. rồi kéo giãn cơ thể

Not necessarily. Hãy often sounds like a polite or standard instruction rather than a harsh command.

Tone depends a lot on context:

• in a classroom or workout setting, it sounds normal and helpful
• in writing, it sounds instructional
• in conversation, it may sound a bit formal if used too often

If you want something softer or more conversational, you could say:

• Khởi động rồi kéo giãn cơ thể nhé.
• Mình khởi động rồi kéo giãn cơ thể đi.

These versions add a friendlier spoken feel.

So the original sentence is not rude; it is just more instructional in tone.