In recent years, hematopoietic stem cell transplantation (HSCT) has been largely used to cure not only many hematologic malignancies but also autoimmune diseases and even genetic diseases. Advances in the HSCT and other cancer treatment approaches including supportive care practices provide patients better survival time nowadays. However, as life expectancy for recipients is increasing up to 85% for being alive 10 years after HSCT, post-HSCT complications are concurrently increasing. After HSCT, recipients may suffer from many infectious complications, cytopenia, immunosuppression, graft versus host disease, a lot of organ involvements and even secondary malignancies. In addition, they are also exposed to immobility condition, physical inactivity, depressive symptoms, psychosocial distress, fatigue, and complications of musculoskeletal, respiratory and cardiovascular systems rely on mostly treatments and treatment related with complications all of which have a negative impact on the survival, physical functions and quality of life of recipients. Hence, the guidelines recommend to all recipients both routine evaluations of clinical and cardiovascular risk factors, and also complying with healthy life style including doing regular physical activity and exercises.

On the other hand, chemotherapy, radiation therapy and further conditioning regimens are required to exterminate the abnormally proliferating cancer cells in patients with hematologic malignancies before HSCT, which also leads to pre-HSCT complications. These complications are observed as physical inactivity, abnormal pulmonary functions, muscle weakness, decreased exercise capacity, evident fatigue, psychological mood disorders and poorer quality of life in these patients until HSCT. Should immobility and physical inactivity extend, the patients may need to respiratory support including oxygen supply, noninvasive or invasive mechanic ventilation. As previously shown, these impairments especially physical inactivity have even existed in patients with hematologic malignancies at the period of pre-diagnosis and early diagnosis. While 33.8% of patients (n=438) could achieve the daily/weekly exercise criteria of guidelines during the time of pre-diagnosis, only 6.5% of patients could perform physical activity during anticancer treatments. In that study, physical activity level was evaluated using a questionnaire, and the patients meeting public health exercise guidelines have reported higher quality of life level. According to results of another study with higher sample size (n=3060), 1392 (46%) of patients are physically active based on their responses to questions at the pre-diagnosis period. However, the most striking result to emerge from the data in 2018 is that these active patients have considerably higher survival rates rather than insufficiently active patients. As demonstrated in 2014 (n=29), 61% of patients with early diagnosis meet the physical activity guidelines, and patients walk about 6.149 steps/d before the start of chemotherapy which was evaluated via a tri-axial accelerometer. As known, although patients have survived after HSCT, these problems have not meliorated in survivors over a long time after HSCT. Therefore, guidelines recommend that the patients should be oriented for rehabilitation in order to maximize muscle strength, functional mobility and quality of life of patients before the patients are subject to the process of HSCT.

Evaluation and counseling of physical activity have become one of the most challenging topics recently; however, there is confusion in the meaning and usage of this term. Original definition of physical activity is "Physical activity is defined as any bodily movement produced by skeletal muscles that results in energy expenditure. Physical activity in daily life can be categorized into occupational, sports, conditioning, household, or other activities. Exercise is a subset of physical activity that is planned, structured, and repetitive and has as a final or an intermediate objective the improvement or maintenance of physical fitness.". In the literature, researchers have mostly tend to only one aspect of physical activity measurement in candidates of HSCT which is either steps count or estimation of physical activity intensity as regard to metabolic equivalent of daily task (MET). In fact, reason of this situation was that less objective tools such as questionnaire, questions, and pedometers were used to evaluate physical activity level in candidates. There is just a few studies used an objective device like triaxial accelerometer in the literature.

Physical inactivity as a cardiovascular risk factor is related with higher risks of cardiovascular diseases and complications after HSCT. Therefore, it is important to assess detailed physical activity along with its all aspects including energy expenditure, number of steps, activity types and durations in candidates of HSCT. However, impairments in energy expenditure, physical activity duration, metabolic equivalents of daily task (METs) and lying down duration are still unknown in candidates versus healthy individuals who are age and gender matched counterparts of candidates. Hence, it was aimed to compare physical activity parameters, pulmonary functions and quality of life scores of candidates with healthy individuals in the current study.