Table 1.

Objectives and hypotheses of the study

Objectives	Hypotheses
Main objective • To evaluate the effect of a 6-week whole-body vibration-training vs. placebo on clinician-rated severity of depression symptoms in adolescent inpatients experiencing a major depressive episode	Main hypothesis • In adolescent inpatients experiencing a major depressive episode, the change in the Children’s Depression Rating Scale-Revised raw-scores from baseline to completion of the 6-week intervention differs significantly between the whole-body vibration strength-training group and the control group (hypothesis A)
Secondary objectives • To evaluate the effect of a 6-week whole-body vibration-training vs. placebo on hypothalamic-pituitary-adrenal axis dysregulation in adolescent inpatients experiencing a major depressive episode	Secondary hypotheses • In adolescent inpatients experiencing a major depressive episode, the change in cortisol awakening response from baseline to completion of the 6-week intervention differs significantly between the whole-body vibration-training group and the control group (hypothesis B)
• To evaluate the effect of a 6-week whole-body vibration-training vs. placebo on neurotrophin and growth factor expression in adolescent inpatients experiencing a major depressive episode	• In adolescent inpatients experiencing a major depressive episode, the change of brain-derived neurotrophic factor and insulin-like growth factor 1 serum levels from baseline to completion of the 6-week intervention/to 8 weeks’ follow-up differs significantly between the whole-body vibration-training group and the control group (hypothesis C)
• To evaluate the effect of a 6-week whole-body vibration-training vs. placebo on inflammatory-marker expression in adolescent inpatients experiencing a major depressive episode	• In adolescent inpatients experiencing a major depressive episode, the change in tumor necrosis factor-alpha, interleukin-6, C-reactive protein serum levels from baseline to completion of the 6-week intervention/to 8 weeks’ follow-up differs significantly between the whole-body vibration-training group and the control group (hypothesis D)
• To evaluate the effect of a 6-week whole-body vibration-training vs. placebo on self-perceived severity of depression symptoms in adolescent inpatients experiencing a major depressive episode	• In adolescent inpatients experiencing a major depressive episode, the change of Beck’s Depression Inventory-second edition raw-scores from baseline to completion of the 6-week intervention/to 8 weeks’ follow-up/to 20 weeks’ follow up differs significantly between the whole-body vibration-training group and the control group (hypothesis E)
• To evaluate the sustainability of the effect of the 6-week whole-body vibration-training vs. placebo on clinician rated severity of depression symptoms in adolescent inpatients experiencing a major depressive episode	• In adolescent inpatients experiencing a major depressive episode, the change of Children’s Depression Rating Scale-Revised raw-scores from baseline to 8 weeks’ follow-up/to 20 weeks’ follow-up differs significantly between the whole-body vibration-training and the control group (hypothesis F)