Final answer:
The main concern when prescribing flexibility exercises to someone with osteoporosis is the risk of fractures due to decreased bone density, so exercises should be low-impact to minimize stress on the bones.
Step-by-step explanation:
When prescribing flexibility exercises to a client with osteoporosis, the primary concern should be the increased risk of fractures due to decreased bone density. Osteoporosis leads to weakened bones that can fracture more easily, especially during activities that place stress on the bones. Flexibility exercises need to be tailored to avoid excessive force that could cause fractures, and to maintain an emphasis on enhancing joint mobility and muscle strength without overstraining the skeletal system. Safe, low-impact exercises such as swimming, water aerobics, and biking are recommended because they put relatively little stress on the joints and help in maintaining joint stability.