I like to think that I am in pretty good shape. I work out five to six times per week, have run multiple marathons and, well, I am the senior fitness editor for Health. Still, there are times when I find myself winded after climbing a flight or two of stairs. What gives?

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“You’re introducing a new variable very quickly,” explained Joe Holder, a Nike running coach and trainer and a performance coach at S-10 Training in New York City. “You go from resting to doing something very quickly that’s typically under 10 seconds. That means you’re going to be in an oxygen-depleted environment, and then have to go back to normal; your body takes a second to catch up.”

Added Frank Baptiste, founder of Frankly Fitness in New York City: “In order to deliver more oxygen to more muscles you’re going to start breathing heavier to take in that oxygen and your heart rate is going to increase to deliver it to your muscles.”

The good news: It’s totally normal to get winded—when you start to huff and puff, however, depends on the individual. Each person has a threshold, notes Holder, and if those steps are long enough, you’ll end up breathless.

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“Depending on the amount of steps, you get to a point where it becomes more and more conditioning,” explained Holder. “Some people get through 4 steps without being winded, and it's nothing, some people 8, and some people 12. You have to find out what your threshold is. Those short first bursts don’t need oxygen, but then there’s that transition period where it’s like alright, your body starts to know that [it has] to use oxygen a little bit more, and that’s when you’re like, oh whoa, you’re a little bit tired.”

So is there anything you can do to get a handle on your breathing while going vertical? The answer is yes. You have to work on your conditioning; the better conditioned you are, the further you’ll be able to push that threshold back. Here, three ways to do just that:

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Take the stairs more

This is pretty self-explanatory. If you want to get better at stairs, do more of 'em; the more accustomed your body becomes, the better you’ll become at this skill. “Half of the problem has to do with the fact that your body isn’t efficient walking up steps," says Holder. Don’t encounter stairs that often? Utilize the stairmaster, he advises.

Add intervals

“This is the best way to make those incremental jumps in your VO2 max, a measure of how well your body uses oxygen,” said Baptiste. “Ultimately how efficient you are in taking in oxygen and using it will allow you to do something as intense as stairs for longer.

His rec: “Go fast up one flight, slow up the next. Or take two steps at a time, and then just one step on each leg after that.”

You can even hop on a stationary bike to help you prepare to conquer that climb, added Holder. “Go as hard as you can for 6 seconds on a bike, slowing down for 20 seconds. This will get you used to maintaining that constant power output while still increasing your volume of work. It will also help you acclimate to repeated short little bursts of energy while at the same time not totally resting, but going into a little bit of a lower intensity.”

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Strengthen your stems

“It is important to decipher whether your lungs are getting tired first, or if it’s a situation where your legs are just beat,” noted Holder. If it’s the latter, you need to shore up your lower body ASAP.

Here’s why:You’re essentially doing repetition after repetition of single-leg body weight squats. You’re only going up, but it’s all of your body weight on one leg,” Baptiste said of the movement, which not only involves multiple muscles, but also requires triple extension (moves that involve the hip, knee, and ankle). To power up your legs, try these three moves from Baptiste:  

Step ups

Why: To build strength and endurance

How to do it: Holding a 15-pound dumbbell in each hand, step up onto a low bench or stair with your right foot, then bring up your left foot, until you are fully standing. Step back down, right foot first. Do 3-4 sets of 10-15 reps per leg. Tip: If you can get through these reps fairly easily, up the weight. Too tough? Go lighter.

Squats

Why: To increase lower body muscular endurance

How to do it: Stand with feet shoulder-width apart, chest high, abs drawn in and hands clasped in front of chest or straight out with palms down. Sit nice and deep, bringing hips to just below parallel. Push into heels to rise to standing. Do 3-4 sets of intervals lasting 30-45 seconds. (Watch this video to see how to do a squat.)


Toe taps

Why: To develop your cardiovascular endurance

How to do it: Stand with a ball (medicine, soccer, or rubber playground ball) or a low box in front of you; tap your right toe on the ball or box. Jump up as you switch feet in the air, landing with the left toe on the ball or box. Continue alternating feet as fast as you can. Try it Tabata style: Perform 4 sets of 20 seconds of work and 10 seconds of rest. This is one round; do 2-3.

This article originally appeared on Health.com.