Owners of adventure dogs tend to be pretty adamant that their outdoorsy pooch is not just great, but the best adventure dog ever. A sweet and understandable sentiment, if an entirely subjective one. But now, the world’s biggest fitness app is making it possible for people to back up their talk with some cold hard numbers. That’s right: Strava for...

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　　Water is heavy—one liter weighs 2.2 pounds, and four liters weighs almost nine pounds. Even the best-designed hydration packs or vests, waistbelts, or handheld carrying systems don’t make water any less heavy than it is. A good system does, however, distribute that weight effectively and allows you to carry what you need comfortably. 　　Figuring out what amount of fluid you...