Перед каждым упражнением я делаю глубокий вдох, а на усилии — выдох.

Because перед normally takes the instrumental case when it means before / in front of.

So:

• каждый → каждым
• упражнение → упражнением

That gives перед каждым упражнением = before each exercise.

This is a very common pattern:

• перед тренировкой — before the workout
• перед сном — before sleep
• перед уроком — before the lesson

So the key point is: перед + instrumental.

Because каждый means each, and in Russian it is normally followed by a singular noun.

So:

• каждое упражнение — each exercise
• перед каждым упражнением — before each exercise

This is just like English:

• each exercise, not each exercises

If you wanted a plural idea instead, you would use something like:

• перед всеми упражнениями — before all the exercises

But каждым упражнением is correct for before each exercise.

Делаю is the imperfective form, and here it shows a habitual / repeated action:

• Перед каждым упражнением я делаю...
  = Before each exercise, I do / I take...

This means it is something the speaker does regularly as part of a routine.

If you used сделаю, it would usually sound like a single completed future action:

• Я сделаю глубокий вдох — I will take a deep breath

So in this sentence, делаю is used because the speaker is describing a general practice or repeated habit, not one single future event.

Russian often uses the noun вдох with a light verb like делать / сделать:

• делать вдох — to take a breath / inhale
• сделать вдох — to take a breath once

So делаю глубокий вдох is very natural and idiomatic, much like English take a deep breath.

You could also use a verb:

• вдыхаю — I inhale
• выдыхаю — I exhale

But делаю глубокий вдох sounds especially natural in instructions, fitness, breathing advice, and medical contexts.

Because вдох is the direct object of делаю, so it is in the accusative case.

The phrase is:

• делаю вдох — I take a breath

Since вдох is a masculine inanimate noun, its accusative singular looks the same as the nominative singular:

• nominative: глубокий вдох
• accusative: глубокий вдох

So even though it is accusative here, the form stays глубокий вдох.

Here а marks a contrast or pairing between two related actions:

• deep inhale
• exhale during effort

So the sentence is structured as:

• before each exercise — inhale
• during exertion — exhale

Using а helps set those two parts against each other in a clear, balanced way.

Compare:

• и = and, simple addition
• а = and / while / but, with contrast or comparison

In this sentence, а is better because the speaker is contrasting two different breathing phases.

In exercise or coaching language, на усилии means something like:

• during the exertion
• at the moment of effort
• on the hard part of the movement

It refers to the phase where you are actively pushing, lifting, pressing, standing up, etc.

For example:

• when pushing a weight up
• when standing up from a squat
• when doing the hardest part of a movement

So на усилии — выдох means exhale on the exertion phase.

This is common gym / training wording. In more neutral language, you might also hear:

• при усилии — during exertion

Because here на is used with the prepositional case to mean something like during / at the stage of.

The noun is:

• усилие — effort, exertion

Its prepositional singular is:

• на усилии

So this phrase is not about movement onto something. It is more like being at a certain phase or condition.

A useful contrast:

• на стол — onto the table (accusative, movement toward)
• на столе — on the table (prepositional, location)

Similarly, на усилии is a kind of situational phrase: at the point of exertion.

The dash shows an omitted word or words that are understood from the first half of the sentence.

Fuller versions could be:

• ..., а на усилии делаю выдох.
• ..., а на усилии — делаю выдох.
• ..., а на усилии выдыхаю.

Russian often leaves out repeated material when it is obvious. The dash helps mark that omission and gives the sentence a crisp, instructional rhythm.

So the second part effectively means:

• and during exertion, [I do an] exhale
• more naturally: and during exertion, I exhale

Yes. Выдох is a noun, meaning exhalation / exhale.

It pairs with:

• вдох — inhalation / inhale
• выдох — exhalation / exhale

Related verbs are:

• вдыхать / вдохнуть — to inhale
• выдыхать / выдохнуть — to exhale

So the sentence is using two parallel noun phrases:

• делаю глубокий вдох
• на усилии — выдох

That parallelism makes it sound compact and instructional.

Yes, absolutely. A more explicit version would be:

• Перед каждым упражнением я делаю глубокий вдох, а на усилии выдыхаю.

That is very natural.

The version with выдох is more compressed and sounds a bit like coaching shorthand or instruction language. Russian often does this in exercise, medical, or procedural speech.

So both are fine:

• ...на усилии выдыхаю — more explicit
• ...на усилии — выдох — more compact, punchier

Yes, the word order is flexible.

You can say:

• Перед каждым упражнением я делаю глубокий вдох...
• Я перед каждым упражнением делаю глубокий вдох...

Both are grammatical.

The original version puts перед каждым упражнением first to highlight the time frame: before each exercise. That is a very natural choice when giving instructions or describing a routine.

Russian word order often changes to shift emphasis rather than basic meaning.

Usually упражнение means an exercise as a unit, like:

• a squat
• a push-up exercise
• a stretching movement
• a drill

In real gym speech, context matters. Depending on the situation, someone might mean:

• before each exercise
• before each set
• before each repetition

But the most direct reading is before each exercise.

If someone wanted to be more specific, they might say:

• перед каждым повторением — before each repetition
• перед каждым подходом — before each set

So упражнение is broad, and the exact interpretation depends on context.