What you're most focused on during a workout is probably the burn you feel or the resistance you're working against. Unless you're really out of breath, what you're less likely to be focused on — but ought to be — is your breathing.

"Breathing is, of course, critical for life," says Dr. Corbin Hedt, a physical therapist at Houston Methodist. "Our bodies need oxygen to function properly, and breathing is what does that for us. It becomes more important during exercise, a time when our bodies are in need of more oxygen than usual. But breathing is easy to neglect when all of your concentration is on completing your workout."

Ignoring your breathing during exercise becomes a problem when it leads to making mistakes that can affect your workout.

Why proper breathing during exercise is important

To understand why breathing properly while exercising is so important, it helps to start by looking at what happens in your body when you breathe:

• Your lungs take in the oxygen and move it into your bloodstream
• Your circulatory system distributes this oxygen throughout your body
• Your muscles then use the oxygen delivered to create the energy needed to function optimally

Put another way, the oxygen you breathe acts as fuel for your body.

"When you exercise, you're increasing your body's need for oxygen because it's now working harder," explains Dr. Hedt. "Optimal breathing ensures an adequate supply of oxygen reaches your organs and tissues, helping to maintain a high level of performance but also to reduce the chance of your body needing to overcompensate (hyperventilate) afterwards to get these systems back to normal."

It's why improper breathing during exercise can lead to:

• Reduced workout performance
• Delayed muscle recovery
• Situations that put your health at risk

In regard to the latter, a lack of breathing during exercise can cause a huge spike in your blood pressure, which, depending on the circumstances, can be incredibly dangerous.

"Maybe you've heard of someone passing out while doing a super heavy deadlift," warns Dr. Hedt. "This can happen if the person is so focused on their lift that they hold their breath, causing their blood pressure to go haywire."

And even in the absence of a scary event like this, the unnecessary blood pressure spike that can occur from accidentally holding your breath during a workout isn't particularly healthy.

3 common breathing mistakes people make during exercise

We breathe without thinking. So do we really need to think about it during a workout? You might if you're making one of these common breathing mistakes:

1. Not regulating your breathing

Whether running, weightlifting or something else, Dr. Hedt stresses the importance of maintaining consistent breath work as much as possible.

"When your breathing is regulated, your body and muscles receive the steady stream of oxygen it takes for them to operate most effectively," says Dr. Hedt. "There's also a calming effect to this. Consistent breathing can help trigger the parasympathetic nervous system, which essentially helps relax your body — allowing for better blood flow."

Unsteady, short or heavy breathing, on the other hand, can have the opposite effect, almost stressing your body out instead.

That said, we all know how taxing a good workout can be, often triggering harder and harder breathing. Does all of this mean that being out of breath is bad?

"We see this with cardiovascular exercise the most," explains Dr. Hedt. "You might be actively pushing the boundaries, where you almost want to become out of breath because that means you're challenging your body to adapt to the stress you're giving it. Whenever you push your body like that, it recalibrates so it can be ready the next time."

It's how you build cardiovascular endurance, so there's a place for it. But don't overdo it.

"Being out of breath can become a hindrance to performance, because now you're not getting enough oxygen to your muscles and the rest of your body," explains Dr. Hedt. "You don't want to be out of breath your whole workout. This is where conditioning comes in, slowly pushing yourself to build this endurance over time so you get better and better each workout."

2. Holding your breath

We've all been there — especially if "there" is toward the end of a set of heavy dumbbell bench presses or the last 30 seconds of a sprint — when we realize we haven't really been breathing at all.

"When you're doing a heavy lift or something at a high intensity or velocity, it's easy to forget about your breathing," says Dr. Hedt. "It can get to the point where you're so focused on all the effort it's taking to perform the activity or motion, you forget to breathe entirely."

This is a big no-no. Not only can it lead to those huge blood pressure spikes, but it can also hinder your recovery between sets and even your overall exercise recovery.

"Even though you finish that set, you may not rebound as quickly before your next one, or between workouts, because your body now has to do a lot more to get your respiratory rate back to normal," says Dr. Hedt. "We talked about the calming effect of consistent, controlled breathing, but now that's kind of out the window because you're entering your next workout already playing catch up."

3. Not utilizing diaphragmatic breathing beforehand

Related to holding your breath but slightly different is how you should breathe before beginning a particular activity.

"Where people sometimes go wrong is, right before doing something intense, you see them almost hyperventilate as they try to psych themselves up to do this really hard thing," says Dr. Hedt. "They're huffing and puffing for five to 10 seconds, and now they're going into their lift or whatever it is with a less efficient respiratory rate."

Instead, Dr. Hedt recommends engaging in what's called diaphragmatic breathing, or belly breathing — starting your breaths from deep within your abdomen.

"Diaphragmatic breathing is when you breathe in from your belly, helping your diaphragm to expand your lungs," explains Dr. Hedt. "This can help you find that consistent, calm breathing that you need to perform optimally."

How to breathe while working out

No matter what type of workout you're doing, proper breathing is important. What it looks like, though, does vary.

Knowing when to inhale and exhale during exercise is usually more important for weightlifting or resistance training, for instance. Whereas how to breathe consistently during a workout has its largest impact during cardio, like running.

When to inhale and exhale while weightlifting

Inhaling and exhaling is of course important for any activity, but you can get the most systematic with it while lifting weights.

• Exhale slowly on the concentratic (lifting) component
• Inhale slowly on the eccentric (lowering) component

"When you're inhaling, the important thing is to make sure it's not too big of a gasp of air," adds Dr. Hedt.

And between sets, don't forget to engage in some diaphragmatic breathing.

"This is when we want you to take those big, slow breaths, letting your belly really expand and release, so you can enter your next lift calm, collected and able to regulate your inhalations and exhalations properly," explains Dr. Hedt.

How to breathe consistently during cardio

"Your muscles need even more oxygen than usual during aerobic exercise, like running, cycling or elliptical," says Dr. Hedt. "These are lower-intensity exercises where a specific action is performed repetitively, and your body is actively and continuously using oxygen to create the energy needed to do so."

Depending on how conditioned you are, your body can do this in perpetuity, essentially — taking the oxygen delivered to muscles through an energy-creating cycle over and over.

It's these exercises where regulated breathing — consistent shallow breaths in, consistent shallow breaths out — becomes critical.

And Dr. Hedt adds that there's greater benefit if these breaths aren't taken through your mouth.

"With aerobic exercise, studies show that you can improve your efficiency by as much as 25% just by nasal breathing, inhaling and exhaling through your nose," says Dr. Hedt. "It's something you might need to get the hang of over time, but certainly something to consider if you're an endurance runner or do a lot of cardio."