The purpose of this study was to examine the association between nine measures of limb and trunk flexibility and running economy. Within a week prior to running economy assessment, and after 10 min of jogging at 3.13 m·s-1, 19 well-trained male sub-elite distance runners underwent two complete sets of lower limb and trunk flexibility assessments. Runners then completed two 10-min running economy assessment sessions on consecutive days at 4.13 m·s-1 following two 30-min sessions of treadmill accommodation at 4.13 m·s-1. Intraclass correlation coefficients indicated that the repeated flexibility measurements were highly reliable([horizontal bar over]X R = 0.92 ± 0.09), as were the two running economy appraisals (R = 0.99). Correlational analyses revealed that dorsiflexion (r = 0.65) and standing hip rotation (r = 0.53) were significantly (P ≤ 0.05) associated with the mean aerobic demand of running, such that runners who less flexible on these measures were more economical. Although speculative, these results suggest that inflexibility in certain areas of the musculoskeletal system may enhance running economy in sub-elite male runners by increasing storage and return of elastic energy and minimizing the need for muscle-stabilizing activity.
Department of Exercise and Sport Science, The University of North Carolina at Greensboro, Greensboro, NC
Submitted for publication February 1995.
Accepted for publication January 1996.
This work was supported by the Susan Stout Fellowship offered by the Exercise and Sport Science Department at the University of North Carolina at Greensboro.
Address for correspondence: Mitchell W. Craib, Ph.D., Sport Studies Department, Guilford College, 5800 West Friendly Ave., Greensboro, NC 27410.