Running economy and delayed onset muscle soreness

Background. The main purpose of this study was to test the effects of a dua thlon competition on running economy. Methods. Experimental design: a prospective study, Setting: University, Par ticipants: nine male and six female physical education students, which mean (SEM) age was 24.0 (1.3) years. Measures: subjects participated in two com petitive duathlons: D1 and D2 (5 km running + 16 km cycling + 2 km running) . Before D1, an incremental exercise test on the treadmill was performed to determine the (V) over dot O-2max, the running speed at exhaustion (vmax), and the (V) over dot O-2, as well as the running speed (upsilon) attained at the first and second ventilatory threshold ((V) over dot O2VT1, upsilon (V) over dot T-1, (V) over dot O-2 (V) over dot T-2, u(V) over dot T-2), Tw o days later running economy (RE1) was assessed at four different speeds co rresponding to 58, 63, 67 and 71% of the upsilon max, During the following six weeks the subjects trained 4 days a week, running all them 210 km in to tal. At the end of the training program the incremental exercise test and t he duathlon competition were repeated (D2), Two and seven days after the se cond duathlon running economy was measured again (RE2 and RE3, respectively ), Results. Small, but significant improvements were observed in duathlon perf ormance, (V) over dot (2max), upsilon (V) over dot T-1, (V) over dot O-2 (V ) over dot T-2 and upsilon (V) over dot T-2, after training. Two days after D2 the oxygen cost of running was similar to5% higher than seven days afte r D2 (p<0.001), The respiratory exchange ratio increased by <similar to>0.0 4 units between RE2 and RE3 (p<0.001), However, the increase in fat oxidati on in RE2 only accounted for <similar to>20% of the extra oxygen cost of ru nning (RE2 vs RE3). No significant differences across tests were observed f or ventilation ((V) over dot (E)), heart rate, (V) over dot CO2 and (V) ove r dot (E)/(V) over dot CO2. Conclusions. This study shows that two days after a duathlon competition ru nning economy is impaired, however, seven days after the competition the ox ygen cost of running is restored.