Backpack Fit Guide: Shoulder Strap Posture Checks That Actually Matter Wear both straps every time and tighten them until the pack sits snug against your back, with the bottom resting above your hips rather than below the waist. If a strap gaps behind your shoulder, digs into the front of it, or your arms tingle, the fit is wrong, and a sternum strap won't fix it. By Chester Takau · October 2026 The short answer: Wear both straps, every time. Tighten them until the pack sits snug against your back, with the bottom resting above your hips rather than hanging below the waist. The American Academy of Orthopaedic Surgeons (AAOS) recommends two wide, padded straps and a pack that "fits snugly and stays close to the body." If a strap gaps behind your shoulder, digs into the front of it, or your arms tingle, the fit is wrong, and no sternum strap will fix it. Chester Takau, TokMind Chester Takau writes about sustainable school gear from a Pacific-Island perspe...