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  • Author: Fernando Sanz-López x
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This study aimed to analyse the effects of running velocity on spatiotemporal parameters and step variability in amateur endurance runners, according to sex. A group of 51 males and 46 females performed an incremental running test on a treadmill (10-16 km/h). Spatiotemporal parameters (contact and flight time, step length, step frequency and step angle [CT, FT, SL, SF, SA]) and step variability, in terms of within-participant standard deviation (SD), were recorded through the OptoGait System. The ANOVA showed significant differences in the magnitude of the spatiotemporal parameters as running velocity increased (p < 0.001). It also revealed significant differences in step variability (p < 0.005) over the entire running protocol. Between-sex differences in CT, SL, SL-normalized and SF (p < 0.05, ES = 0.4-0.8) were found. Differences were also found in step variability at high velocities (15-16 km/h), with males showing a greater SD than females. In conclusion, increasing running velocity makes CT shorter, FT and SL longer, and SF and SA greater in amateur endurance runners, changing step variability, regardless of sex. Additionally, some between-sex differences were found in spatiotemporal parameters and step variability.


The aim of this study was to analyse the acute effects of a concentric exercise and two different eccentric overload exercises (EOEs) on blood markers of muscle damage (i.e. creatine kinase [CK], lactate dehydrogenase [LDH], myoglobin [Myo], and malondialdehyde [MDA]) and muscle contractile properties. Ten healthy, young (27 ± 1.5 years, 179 ± 6 cm, 78.7 ± 10.8 kg), physically active men (3.5 ± 1.9 h·w-1) randomly performed three training sessions using the following protocols: a half-squat (HS) as a concentric exercise, and exercises using Versapulley (VP) or YoYo isoinertial technology (YIT) as EOEs (4 x 7 repetitions with a 2 min rest interval between sets). Blood samples and tensiomyography measurements were obtained after each training session. Repeated measures analysis of variance (ANOVA) followed by the Tukey test was used to detect differences between the four time points of each variable. The standardized difference or effect size (ES, 90% confidence limit) in the selected variables was calculated using the basal SD. After all exercises, a greater activity of CK, LDH, and concentration of Myo, and MDA were found compared to baseline values (p < 0.05). A substantially greater activity of CK, LDH, and Myo concentration, but not MDA, were found after EOEs when compared to the HS protocol. Substantially lower tensiomyography results in the rectus femoris (RF) were reported, irrespective of the exercise mode performed. Also, no substantial differences were obtained in the biceps femoris (BF) between EOEs and the HS protocol. Time of contraction (Tc) in the RF was possibly to very likely lower in the HS in comparison to EOEs. Additionally, muscular displacement (Dm) in the RF was substantially lower in the HS compared to EOEs. VP produced higher concentrations of damage markers than YIT and concentric exercise did. Furthermore, tensiomyography variables showed similar activation in both exercises, although higher specific fatigue (in the RF) was registered in the traditional HS.