Running economy is negatively related to sit-and-reach test performance in international-standard distance runners

Jones, Andrew M. (2002) Running economy is negatively related to sit-and-reach test performance in international-standard distance runners. International Journal of Sports Medicine (IJSM), 23 (1). pp. 40-43. ISSN 0172-4622

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Abstract

The purpose of this study was to investigate the relationship between running economy (RE) and lower body flexibility. Thirty-four international-standard male distance runners (mean ± s, age 27 ± 5 years; body mass 64.9 ± 4.2 kg; V˙O2max 72.8 ± 3.7 ml × kg-1 × min-1) gave written consent to participate in this study. The subjects performed an incremental treadmill test for the assessment of RE, lactate threshold and V˙O2max, and the sit-and-reach test was used to assess their general lower body and trunk flexibility. Running speeds below the lactate threshold were used to explore the relationship between running economy and sit-and-reach test performance. At 16.0 km × h-1, the V˙O2 was 50.6 ± 3.7 ml × kg-1 × min-1 (range: 44.2 to 57.1 ml × kg-1 × min-1). Pearson product moment correlation coefficients revealed no significant relationships between aerobic demand at 16.0 km × h-1 and age (r = - 0.19), height (r = 0.15), body mass (r = - 0.18), or V˙O2max (r = - 0.004). However, there was a highly significant relationship between aerobic demand at 16.0 km × h-1 and the sit-and-reach test score (r = 0.68; p < 0.0001). These results suggest that the least flexible runners are also the most economical. It is possible that stiffer musculotendinous structures reduce the aerobic demand of submaximal running by facilitating a greater elastic energy return during the shortening phase of the stretch-shortening cycle.