Strength training and changes in the dynamics of running economy

Abstract

The aim of this study was to examine an acute effect of 4RM training and plyometric training (PT) on running economy (RE; O2 consumption) in endurance runners during a 48 hour interval. Eight performance runners (age 25.4±1.4 years) completed a maximum strength training (4RM) of lower limbs (3 sets, rest 2 min, 5 exercises) and subsequently underwent a RE test on a treadmill (speed 8, 10 and 12 km·h-1) at three time intervals (0, +24 and +48 h) after the training. We found that the average VO2·BM-1·min-1 and ΔVO2·BM-1·min-1 at the given speed increased from baseline (a pretest 48 h before the strength intervention) by 2.3-5.6% and culminated after 24 h. These changes in RE after the strength intervention were not statistically significant, when compared to the pretest (48 h before the intervention). The second investigation was conducted in seven runners (age 25±1.6 years). This time the intervention was plyometric (7 sec load, rest 2 min, maximum intensity, 3 sets, 6 exercises on the dominant lower limb). We found that the average VO2·BM-1·min-1 and ΔVO2·BM-1·min-1 at given speeds at intervals 0, +24 and +48 h did not increase, when compared to the pretest (p < 0.05; max +1%). These minimal changes probably resulted from the design of the PT, which had not a sufficiently destructive effect on muscle cells. The comparison of these two investigations indicates a stronger (although statistically insignificant) deterioration of RE after 4RM training versus PT.