The purpose of this investigation was to examine the influence of running velocity, stride characteristics, training background, gender, and caliber of a runner on the changes in ground contact time during a 400-m run. Thirteen male and 4 female sprinters ran a 400-m time trial on the track, and 8 male sprinters and 6 male endurance athletes ran a simulated 400-m trial at constant velocity on the treadmill. A special shoe insert was placed in the track spike to determine contact time, and a video camera was used to determine split times for each 40 m. Two threshold points were identified during the 400-m run, with the first occurring when the running velocity began to decrease. The threshold points were affected by the individual running strategy and reflected fatigue-induced changes in the running velocity; they also were independent of gender, training background, and caliber of an athlete.
Ari Nummela, James Stray-Gundersen, and Heikki Rusko
Ritva S. Taipale, Jussi Mikkola, Ari T. Nummela, Juha Sorvisto, Kai Nyman, Heikki Kyröläinen, and Keijo Häkkinen
To examine acute responses of force production and oxygen uptake to combined strength (S) and endurance-running (E) loading sessions in which the order of exercises is reversed (ES vs SE).
This crossover study design included recreationally endurance-trained men and women (age 21−45 y; n = 12 men, 10 women) who performed ES and SE loadings. Force production of the lower extremities including countermovement-jump height (CMJ) and maximal isometric strength (MVC) was measured pre-, mid-, and post-ES and -SE, and ground-reaction forces, ground-reaction times, and running economy were measured during E.
A significant decrease in CMJ was observed after combined ES and SE in men (4.5% ± 7.0% and 6.6% ± 7.7%, respectively) but not in women (0.2% ± 8.5% and 1.4% ± 7.3% in ES and SE). MVC decreased significantly in both men (20.7% ± 6.1% ES and 19.3% ± 9.4% SE) and women (12.4% ± 9.3% ES and 11.6% ± 12.0% SE). Stride length decreased significantly in ES and SE men, but not in women. No changes were observed in ground-reaction times during running in men or women. Performing S before E caused greater (P < .01) oxygen uptake during running in both men and women than if E was performed before S, although heart rate and blood lactate were similar between ES and SE.
Performing S before E increased oxygen uptake during E, which is explained, in part, by a decrease in MVC in both men and women, decreased CMJ and stride length in men, and/or an increase in postexercise oxygen consumption.
Ville Vesterinen, Ari Nummela, Sami Äyrämö, Tanja Laine, Esa Hynynen, Jussi Mikkola, and Keijo Häkkinen
Regular monitoring of adaptation to training is important for optimizing training load and recovery, which is the main factor in successful training.
To investigate the usefulness of a novel submaximal running test (SRT) in field conditions in predicting and tracking changes of endurance performance.
Thirty-five endurance-trained men and women (age 20–55 y) completed the 18-wk endurance-training program. A maximal incremental running test was performed at weeks 0, 9, and 18 for determination of maximal oxygen consumption (VO2max) and running speed (RS) at exhaustion (RSpeak) and lactate thresholds (LTs). In addition, the subjects performed weekly a 3-stage SRT including a postexercise heart-rate-recovery (HRR) measurement. The subjects were retrospectively grouped into 4 clusters according to changes in SRT results.
Large correlations (r = .60–.89) were observed between RS during all stages of SRT and all endurance-performance variables (VO2max, RSpeak, RS at LT2, and RS at LT1). HRR correlated only with VO2max (r = .46). Large relationships were also found between changes in RS during 80% and 90% HRmax stages of SRT and a change of RSpeak (r = .57, r = .79). In addition, the cluster analysis revealed the different trends in RS during 80% and 90% stages during the training between the clusters, which showed different improvements in VO2max and RSpeak.
The current SRT showed great potential as a practical tool for regular monitoring of individual adaptation to endurance training without time-consuming and expensive laboratory tests.