High-impact sports bras for women with large breasts (we’re talking D and up) have experienced serious design innovation to manage the complex, three-dimensional movement of boobs in motion. Makers of Nike’s Fe/Nom Flyknit Bra used 600 hours’ worth of biometric testing data to inform their seamless design; Lululemon’s Enlite Bra features Ultralu, a futuristic fabric invented by the company to support breasts without flattening them. Yet such high-tech stabilizing garments don’t mean jack on a trail run if you’re wearing a backpack or hydration vest that chafes, squishes or, as one (not featured!) pack did to me on a recent run, somehow nuzzle up to your jugular vein.

It’s a common misconception that most female long-distance runners have small breasts. While this may be generally true for elite or professional runners—a small 2016 study published in the European Journal of Sport Science found that smaller-breasted runners generally had faster marathon finishing times than women with larger breasts—according to Nancy Hobbs, executive director of the American Trail Running Association, women of all shapes are entering the sport at a rapid pace. The association’s annual trail-running survey found that 48 percent of trail runners in 2018 are women, up six percent from last year.

Smart brands are designing vests that fit women with different body shapes and sizes, and that often means accommodating breast size. “We feel really passionate about creating products that can fit everyone,” says Katie Voigt, product designer and developer for running gear company Nathan Sports. “I think there are more women runners who are willing to take a chance with adventure sports and who are pushing themselves in the running community. More are saying after their marathon that they want to try that challenging ultra.”

For larger-breasted women, Voigt says it’s best to find a vest with vertically adjustable sternum straps that can be positioned above and below your bust—not directly over it, a position that can grow increasingly uncomfortable with each mile. Additionally, she recommends finding a vest that feels like it’s hugging you rather than sitting on top of you. The goal is to forget about your vest or pack while running.

A D-cup myself, I tested as many women-specific packs and vests as I could get my hands on over the past few months while training for a trail marathon, and I clocked at least 25 miles per item. These are my top picks.

Nathan VaporMag 2.5L ($125)

Best for: Short training runs

At first I didn’t think I was going to like wearing this simple crimson vest, which is named after champion ultrarunner Maggie Guterl. Two sternum straps are the only way you can adjust the circumference of the pack, and its flexible 12-ounce water bottles sat directly on top of my breasts, which added even more weight to the front of my body. Yet throughout my training regimen, I kept reaching for this pack again and again. The inner layer is entirely mesh, which makes it breathable, and its dearth of complicated straps makes it a cinch to throw on before heading out the door. The water-bottle position didn’t end up bothering me because the bottle’s snug pockets abated bounce. Plus, the easy-to-access extended straws let me conveniently sip water without removing a bottle.

Be warned: this vest is pretty small, making it tough to carry any warm clothing with you besides a pair of gloves and maybe a light beanie. Choose a different one if you anticipate big weather fluctuations on your run.

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Ultimate Direction Signature Series 4 Ultra Vesta ($135)

Best for: Any run or hike

This vest quickly became my favorite thanks to its innovative Comfort Cinch fit system, which wrapped around my lower ribs without squeezing them and prevented the vest from bouncing at all. The Ultra Vesta seemed to disappear on my body. The soft water bottles snuggled comfortably against the sides of my torso, and unlike Ultimate Direction’s men’s version of the pack, the Ultra Vesta is reservoir-compatible, giving me the option to carry water on my back. I appreciated the included mini-whistle, as it lessened the sketch factor while running solo through the woods. Also cool: the Ultra Vesta comes in blue if pink isn’t your thing.

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Patagonia Women’s Nine Trails Pack 18L ($129)

Best for: Long, unsupported days in the mountains

Patagonia engineered this burly, tough-as-nails, 100 percent nylon ripstop trail pack with shorter, narrower straps to better hug a woman’s body. Large enough to carry an extra fleece, rainjacket, food, and two liters of water, this pack works for all-day solo runs or hikes through the mountains. I tested it while running (and some walking when it got too steep) a Colorado fourteener, and I was happy to have an extra layer when a cold front rolled in near the summit. This pack earns bonus points for adjustable sternum straps and stretchy, easy-to-reach zippered hip pockets for your phone and snacks. While it feels a little too bulky and big for casual training runs, the Nine Trails is nearly perfect for fastpacking ascents and bombing down scree fields to the trailhead.

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RaidLight Responsiv 10L Race Vest ($170)

Best for: Racing or tempo-training runs

This 210-gram vest is ideal for swift training runs or race day. Notably, the vest features snazzy Freelock adjustment dials on the sides that allowed me to find the optimal fit without missing a stride. I loved being able to position the water bottles more toward my sides rather than directly on my chest, and I liked how the stretchy sternum straps kept the vest in place without feeling like a boa constrictor wrapped around my body. One flaw: this is likely due to my long torso, but the Responsiv rubbed against the back of my neck in an unpleasant way during testing. Also, the sternum straps are sewn in place, and I would have liked to slide the top one higher to avoid placing pressure on my breasts.

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Gregory Maya 5L ($69)

Best for: A minimalist who wants a single pack for trail running and mountain biking

This tough workhorse is roomy enough to pack a two-liter hydration bladder and a light jacket, perfect for shattering your peak-bagging PR. I loved how the Maya 5L’s long sternum-strap rails let me position the top strap comfortably below my clavicle and far away from my breasts. Gregory’s Biosync Suspension Technology—essentially flexible, stretchy tendons that connect the bag to the shoulder straps—reduces bounce. It was a great choice to take on a weekend that included both running and mountain biking. I likely wouldn’t run more than ten miles in this one since more streamlined and lighter options exist, but it’s a good choice if you’re working with a tight budget or limited packing space and want a single bag for biking and running.