Intermittent walking fails to alter physiological responses to a paced 24 km run

The effect of continuous running (CR) and systematic run/walk (R9W1) exercise on physiological variables and running economy was compared in nine novice female runners who completed two randomly assigned 24 km run protocols separated by two weeks. The mean (±SD) VO2 max and age of the runners was 45.7 ± 4.8 ml · min−1 · kg−1 and 34 ± 9 years respectively. The R9W1 consisted of 9 min of running followed by 1 min of brisk walking. The two protocols were matched such that each subject completed both runs in the same elapsed time, which required a mean pace increase of 5.8 ± 1.9 m · min−1 during the running phase of the R9W1. Selected physiological responses V E , VO 2 , heart rate and rating perceived exertion were evaluated during treadmill exercise at the individual CR pace before and after each trial for estimation of running economy. Plasma creatine kinase (CK) activity was measured pre‐, immediately post‐ and at 24, 48 and 72 h after each run. Both protocols resulted in a significantly decreased running economy (p ≤ 0.05), however no difference was observed between the CR and R9W1. The rating of perceived exertion was similar during both protocols. CK activity increased significantly at 24 h after both the CR and R9W1 trials (1135.0 ± 542.79 and 1273.28 ± 376.62 IU · 1−1, respectively), although peak CK activity was not different. These results suggest that regular walking breaks during a paced 24 km run do not reduce fatigue or muscular stress compared with CR when elapsed time is equated.