Testing an association between lower body flexibility and running economy on a level, uphill and downhill grade

The purpose of the study was to determine whether a relationship exists between selected lower body flexibility measurements and running economy (RE) in nine well trained runners and triathletes on a level (0% at 207 m•min^-1), uphill (+7% at 154 m•min^-1) and downhill (-7% at 295 m•min^-1) grade. Each subject underwent a 60-min treadmill accommodation period, VO_2max test, two RE trials on each grade (repeated measures), and lower body flexibility tests. The range of motion (ROM) tests used were standing external hip rotation- hip flexed 90°, supine passive straight leg raise, supine active knee extension- hip flexed 90°, seated dorsiflexion- knee flexed 90°, seated dorsiflexion- hip extended, and seated plantar flexion- knee flexed 90°. The results show several ROM measurements significantly correlated (p< 0.05) with running economy. These include oxygen uptake on a level grade with dorsiflexion- knee flexed (r= .6681); a level grade with plantar flexion (r= .6108); a downhill grade with dorsiflexion- knee flexed (r= .5886); a downhill grade with plantar flexion (r= .5485); and an uphill grade with external hip rotation (r= -.5823). The results of this study show that a significant relationship does exist between submaximal oxygen uptake (running economy) and selected lower body flexibility measurements.