Stand facing a low cable with a rope attachment, palms facing each other in a neutral grip. Curl the rope up toward your shoulders while keeping your palms facing in throughout — no rotating toward your face like a standard curl. Your elbows stay tucked against your ribs and still; only your forearms swing. The cable keeps tension on your arms through the entire range, including the bottom, where a dumbbell version would go slack. Lower back down slowly rather than letting the weight stack drop you, and resist the urge to lean back to finish the rep — that just swaps biceps work for lower back strain.