Impact of Resistance Exercise and Nutritional Endorsement on physical performance in patients with GvHD (IRENE-G study) – design and rational of a randomized controlled trial oleh Janina Bujan Rivera, Rea Kühl, Ulrike Zech, Anne Hendricks, Thomas Luft, Peter Dreger, Birgit Friedmann-Bette, Theresa-Maria Betz, Joachim Wiskemann