Which of the following Reformer exercises is contraindicated for clients with osteoporosis?

The Short Spine Stretch is considered contraindicated for clients with osteoporosis primarily due to the nature of the movement involved. This exercise requires a significant amount of flexion of the spine, which can put undue stress on the vertebrae. For individuals with osteoporosis, whose bone density is reduced and whose bones are more fragile, this added flexion can increase the risk of vertebral fractures.

In contrast, the other exercises listed generally involve movements that promote stability and controlled strength without excessive spinal flexion or strain. Feet in Straps, Bridging, and Standing Arm Work can be modified to ensure that they are safe and supportive of clients with osteoporosis. They can help in building strength and maintaining mobility without putting the spine at risk, making them safer choices for these clients.