The effects of three different stretching interventions on running economy in trained female athletes

The purpose of the current investigation was to determine the effects of three different stretching interventions on running economy (VO2), lactate, and stride length in female distance runners. Twelve trained females (VO2peak = 52.07 ± 3.8 ml·kg -1·min-1) completed five testing sessions. A VO2peak test was administered in the first session. Sessions 2 – 5 included a 10 min warm up at a self-selected speed, flexibility measures (sit and reach, ankle dorsiflexion), stretching intervention, reassessment of flexibility measures, and a 10 min run at 80% VO2peak. Stride mechanics were assessed during the final 10 min run and blood lactate concentration was sampled at completion of the final 10 min run. The stretching interventions included a control (CON) consisting of a 10 min sit; active isolated stretching (AIS) involving 2 sets of 30 s of 5 stretches that were held for 1-2 s and repeated for the 30s period; static stretching (SS) involving 2 sets of 30s of 5 stretches that were held for the 30s time period; and, dynamic flexibility (DF) involving a series of 10 running specific drills repeated for 2 sets of 30s. Differences in VO2 (ml·kg-1·min -1), lactate, and stride length for each condition (control, DF, SS, AIS) were analyzed via a repeated measures multivariate analysis of variance (RM MANOVA) with an alpha levels of .05. The stretching interventions did not have a significant effect on VO2 (p = .110), lactate (p = .105) and stride length (p = .95).The mean values and standard deviations (SD) for VO2 (ml·kg -1·min-1) were 42.13 ± 4.7 (CON), 42.4 ± 4.04 (AIS), 42.13 ± 4.06 (SS), and 42.75 ± 4.6 (DF). Lactate mean values (mmol·L-1) and SD were 4.1 ± 1.6 (CON), 3.4 ± 1.2 (AIS), 3.7 ± 1.4 (SS), and 4.6 ± 1.6 (DE). The mean values for stride length were 2.2 ± .13 for all sessions. In conclusion, AIS, SS, and DE did not alter running performance variables as the submaximal nature of running and the length of the run may have negated the effects of the stretching.