Bone metastases are a very frequent secondary diagnosis associated with an advanced tumor disease, with the vertebral column being the most frequent localization
[17, 18]. Patients affected by this condition are usually immobilized, primarily due to the risk of pathological fractures and the related danger of spinal cord compression. Previous clinical studies have shown that tumor patients may profit from physical training measures during and following medical treatment
[6, 7, 9, 19, 20]. Patients in the intervention group felt less exhausted and less psychically stressed following the training session; moreover, the pain felt during training was less intense. The specific enhancing effects of physical exercise, however, vary according to the degree of the primary disease, the medical treatment principles, and the patient’s current lifestyle
. The German Association for Sports Medicine and Prevention and the German Cancer Society have published guidelines for the design of training and sports programs for tumor patients; in these guidelines, the targeted sports intervention is deemed contraindicated in patients with bone metastases
. The promoting effects of differentiated training to support the vertebral column of patients with bone metastases have not yet been investigated. Current strength-training regimens with strong anabolic effects on muscles and bones may exert an influence in countering specific side-effects of tumor therapy, helping patients to improve their physical function
. A training exertion between 20 and 30% of maximum power causes neither an increase nor a decrease in strength, and can be seen as corresponding with the daily load of induced muscle tensions
. When a patient is immobilized, the muscles are exerted only to a degree not exceeding 20%, resulting in their atrophy
. The training threshold, thus, lies at approximately 30-40% of the maximum muscle strength, above which training can have a positive effect
. This was the level of exercise at which our training program was carried out without extra weights, although it was not possible to measure the maximum strength in these patients. In the intervention group, this training effect resulted in an increase in mobility, chair-stand test and activity questionnaire were used. The quantitative measurement of mobility for these patients was difficult, due the increased risk of pathological fracture. Therefore other methodical devices were not acceptable. We were not able to assess the strengthening of the muscles quantitatively, but this test was almost related to mobility for palliative patients. In addition mobility was evaluated in our non-validated questionnaire. The results of the activity questionnaire further emphasized the benefits attained in the intervention group as opposed to the control group. Other existing validated questionnaires had no information with respect to daily activity in patients with bone metastases, so we created questions independently which were relevant for these palliative patients. The questionnaire was not based on an existing one. However, this represented a major limitation. An adequate training duration corresponds to 20-30% of the time of muscle tension until exhaustion, and this was approximately the limit we used for the exercises
. Regarding age and gender, there are indications of differing degrees to which muscles can be trained; in our study group, however, due to the homogeneous distribution this difference appears to be negligibly small. Lasting only a few seconds, the individual muscle-tension is kept so short that no load is exerted on the cardiovascular system, meaning that these exercises can be carried out also by patients with pre-existing internal diseases. In their review, Knols et al.
 demonstrated that the positive effects of exercise therapy vary depending on the type and stage of tumor, pharmaceutical therapy, therapeutical procedures, and patient lifestyle. In the review of the practicability it was not necessary to standardize the conditions, which is why simple-to-perform exercises were selected to form this standardized training program. On account of the raised risk of fracture, no extra weights were used and active movements of the vertebral column were avoided. As a measure to ensure an adequate training stimulus, which optimally lies at 40-50% of the maximum isometric strength with extra weights, the individual exercises were repeated a number of times, ensuring appropriate pauses between each set of exercises.
A decisive step was to initially classify the metastases as “stable” or “unstable”, which was done according to the Taneichi scores. According to Taneichi et al.
, significant risk factors included the destruction of the costovertebral articulation, the size of the tumor in the thoracic region (Th1-Th10), and the destruction of the pedicle as the main factors in the thoracolumbar and lumbar spine. Not only is the standardized assessment of the stability in clinical practice by means of a score rating of relevance when making the indication for radiotherapy, it also provides important information for decisions regarding mobility therapy. The feasibility of exercise in tumor patients has already been demonstrated by a number of studies
[9, 10, 19, 20, 23, 24]. In their study Murnane et al.
 were able to show that the majority of patients wish to take physical exercise as an adjunct to RT. In our investigation, none of the patients withdrew from training or refused to take part because of the training program. Hayes et al.
 describe that physical exercise is associated with a benefit during and after tumor treatment, and indeed is even capable of reducing the impact of the side-effects of therapy and the symptoms of the underlying disease. The evidence emphasizes the effect of positive physiological and psychological benefits of mobility therapy during and after tumor therapy
The local three-month controls were performed in 100% in both groups; the interesting long-term results have not yet been evaluated, and the results will be presented in the near future.
The pain-reducing effect in the three-month course of the study showed a positive course in Arm A, but not significantly better. In a prospective collective group of 518 patients, Chow et al. were able to demonstrate complete and partial response rates at the 3-month follow up of 21% to 25% and 26% to 30% in RT group, respectively
. Our results in the control group were comparable with these findings: the pain response in the intervention group was 48% and 20% in the three-month course.
There were no significant differences between the groups regarding overall survival (OS). Due to the differing tumor entities and the small number of patients involved, any comparison with other data cannot be representative. The bone survival data showed median values of 23.3 vs. 11.2 months; here, too, it was not possible to demonstrate a significant difference between the two groups.
The weak points of the study were the small number of subjects, the variety of primary tumors, the exclusion of the cervical spine, and the non-validated score of the activity questionnaire, purpose-made for this trial. The patients’ compliance with the training program in their home setting could naturally only be checked by reviewing the documentation forms completed by the patients themselves. The study’s strong points comprised the classification of stability and the very first application of a physical exercise program in patients with metastases in vertebral bodies as a measure to enhance their mobility.