HIF1A and neoplasm: Examination of the modulatory potential of direct and targeted mechanical loading of osteolytic spinal bone metastases will also be conducted by quantifying tumour morphology and systemic activity of metastatic biomarkers (HIF-1α, local hypoxia; TGF-β, transformation growth-like factor), whilst also exploring whether targeted exercise can reduce bone pain, preserve neighbouring skeletal mass and structure (i.e. unaffected vertebrae above and below affected lesion sites) and reduce or avoid exacerbation of bone pain.