2.4. Outcome Measures
SECONDARY
The outcome measures were evaluated at four time points: baseline (T0); one month after baseline but before intervention (T1) to gauge a possible worsening of conditions; at the end of treatment (T2, after completing four weeks of training); and at the follow-up (T3, four weeks after the end of the training program). Outcome measures were collected before hemodialysis sessions.The primary outcome measures were maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), which were assessed by a vacuometer (MicroRPM, MD Spiro, Maine, US). Every test was performed three consecutive times, with a fixed resting period of 30 s within each trial, and the higher value was chosen. If the patients needed more time to recover, a longer suitable resting pause was allowed.The secondary outcome measures included the following: forced expiratory volume at first second (FEV1), forced vital capacity (FVC) and maximal voluntary ventilation (MVV) measured by the Spiropalm 6MWT (Cosmed, Rome, Italy). Concerning the FEV1 and FVC, three trials separated by a 1 min resting period were performed; conversely, MVV was only tested once.Each patient was familiarized with the outcome measures before performing the trials considered as outcomes. All the procedures were conducted according to the international guidelines [Exercise capacity was assessed by a six-minute walk test carried out in a 20 m corridor, with each patient instructed to cover as much distance as possible in the given time [