2.3. Methodology
low back pain, functional disability, pain, FD, LBP
SECONDARY
The sample size was calculated based on a pilot study and the 2 points of clinical relevance established by Ostelo et al. [For recruiting, a non-probabilistic sampling of chain or network selection (“snowball”) was used, through which key participants were identified and added to the sample. They were asked if they knew other people who can provide more extensive data, and once contacted, they were also included [To ensure that exercise intensity was comparable between both situations, the intensity along the TT was established between 60 and 82% of the maximal heart rate (HR), corresponding to the cardiovascular zones 1, 2 and 3 of a total of 5, which are the predominant zones for cyclists in prolonged submaximal efforts, equivalent to an effort of light to moderate intensity [The prespecified primary outcome measure was low back pain perception (LBPP) using a 0 to 10 numeric pain rating scale (NPRS). This is an 11-point scale ranging from 0 (no pain) to 10 (worst imaginable pain) that has been demonstrated to be valid, reliable, and appropriate for use in clinical practice and also with cyclists [Prespecified secondary outcome measures were the pain pressure threshold (PPT) and functional disability (FD) due to LBP measured by the Roland–Morris questionnaire (RMQ) and RPE. PPT was measured from 0 to 10 kg/cmFD was measured only once, at the end of the first assessment day, by using the Spanish version of RMQ [