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Improved temporal sequencing of high - intensity muscle contractions prior to the sprint start may maximize motoneuron excitability and may enhance fast twitch fiber recruitment and sprint start effectiveness. The aim of the study was to assess a) the electromyographic activity of the gastrocnemius lateralis, biceps femoris and vastus femoris muscles under exposure to specific voluntary, dynamic actions (quick skipping or tuck jumps that sometimes sprinters perform after the "on your marks" command) and to an external involuntary stimulus (WBV-whole body vibration) and b) the effectiveness of the above stimuli applied on the activation level of lower limb muscles in order to produce neuromuscular activation the very last moment just behind the blocks, as this is measured by the RT and time in 1.5m and 3m after the sprint start. Ten male sprinters executed sprint starts under 4 experimental conditions after the "on your marks command": 1st condition - without performing any action, 2ndperforming tuck jumps, 3rd performing quick skipping and 4th after being exposed to vibration stimuli. No significant difference in average muscle activity was observed after evaluation of the EMG raw data for the tuck jumps and quick skipping actions. No significant differences were, also, observed for RT and time in 1.5m and 3m in conditions 2 to 4. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of pacing strategies at peak VO2 velocity (vVO2 peak) on performance and selected metabolic parameters. Trained subjects (n = 12) performed an incremental test to determine vVO2 peak followed by a maximal run at constant vVO2 peak (even-pace strategy, EPS) at least 48 hrs afterwards. Two days after the vVO2 peak test, the subjects performed the 2nd or 3rd maximal runs in a random order. The second trial started at a pace 1 km ⋅ h-1 faster than the vVO2 peak velocity (fast-start pacing strategy, FPS) for half of the duration of the EPS trial with the rest of the test at a pace 1 km ⋅ h-1 slower than the vVO2 peak velocity. The third pacing trial started at a pace 1 km ⋅ h-1 slower than vVO2 peak velocity (slow-start pacing strategy, SPS) for half of the duration of the vVO2 peak trial with the rest of the test at a pace 1 km ⋅ h-1 faster than the vVO2 peak velocity. Repeated measures ANOVA showed that FPS produced a significantly longer distance of 2654 ± 1668 m (P<0.05) compared with the EPS of 2001.67 ± 839.63 and the SPS of 1975.83 ± 791.22. The post-exercise blood lactate concentration was lower (P<0.05) after FPS (14.41 ± 3.51 mmol ⋅ L-1) than after SPS (16.16 ± 3.52) or EPS (16.78 ± 3.52). The accumulated oxygen deficit (AOD) was also lower during FPS (30.92 ± 8.39 mL ⋅ kg-1) than during SPS (40.36 ± 10.86). The results indicate that if the duration of maximal effort varies between 4 and 12 min, an uneven fast pace during the initial stages of exercise will produce better performance (longer distances and exercising time). There are also indications that an early, slightly fast pace produces less overall stress on anaerobic metabolism and that decreased metabolic acidosis may explain the improved performance. [ABSTRACT FROM AUTHOR]

Whole-body vibration is a neuromuscular training method and has been suggested as an acute ergogenic aid mode before practice, training and competition activities of athletes. The aim of this study was to investigate the acute effects of a whole-body vibration session on sprint running kinematics and neuromuscular performance in well trained track & field sprinters. 30 sprint athletes participated in this study (age 21.6 ± 4.1 years, height 1.76 ± 5.0 m, body mass 71.2 ± 6.4 kg). Both experimental (with vibration) and control (without vibration) groups performed a single session of whole-body vibration consisted of two dynamic exercises (half squat / lunge) using a body vibration platform (90 s, 50 Hz, 2 mm). Performance tests (60m sprint, counter movement jump, muscle power and sit & reach test) were performed before and after 6 min the whole-body vibration session. Counter movement jump was reduced after whole-body vibration by 3.9%, whereas all the other analyzed parameters remained unchanged. The results of this study do not support the use of whole-body vibration as an acute ergogenic aid during standardized warm-up in well trained track and field sprinters. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the effect of six weeks of whole body vibration (WBV) training on sprint running kinematics and explosive strength performance. The study was participated by 12 men and women who were divided into the experimental and the control groups. According to the authors, the WBV training period of six weeks brought out significant changes to the sprint running kinematics and explosive strength performance.

We determine whether mechanical asymmetries differ between dominant and non-dominant legs at fast treadmill speed. Stride temporal variables, derived from high-speed camera recordings, allowed to estimate leg and vertical stiffness through the sine-wave method in 31 uninjured males during treadmill running at 6.67 m.s -1 . Lower limb dominance was determined by the triple-jump test. The asymmetry was expressed as dominant-non-dominant and indexed by the absolute asymmetry index (ASI). The lowest and highest mean ASI values were detected for contact time (1.69%) and flight time (5.66%), respectively; ASI values for spring-mass characteristics (2.6% ≤ leg and vertical stiffness, peak vertical force, change in vertical leg length and centre of mass vertical displacement ≤ 4.7%) were within this range. Inter-subject variability in ASI varied substantially among the seven analysed variables with larger and smaller range of variability in ASI found for flight time (0-16.56%) and contact time (0-3.47%), respectively. Because the magnitude of group mean ASI appears inconsistent among stride temporal and spring-mass characteristics, different biomechanical variables should not be used interchangeably to assess laterality effects at fast treadmill speed. The widespread ASI range also indicates that using a 'fixed cut-off' threshold is an arbitrary approach.

Biomechanical findings show that running is asymmetric in many kinetic properties. Running stiffness is a vital kinetic property of yet unknown pattern of lateralization. The aim of this study was to examine the degree and variability of lower limb dominance specific asymmetry of running in terms of leg stiffness, vertical stiffness, contact time, flight time, maximal ground reaction force during contact, vertical displacement of the center of mass, and change in leg length. Leg and vertical stiffness was estimated by the sine-wave method in 22 young males during treadmill running at 4.44 m/s. Lower limb dominance was determined by the triple-jump test. Asymmetry was expressed as dominant - non-dominant, and indexed by the absolute asymmetry index. Significant asymmetry was found only in flight time (3.98%) and in maximal ground reaction force (1.75%). The absolute asymmetry index ranged from 1.8% to 6.4%, showed high variation between subjects (0-31.6%), and differentiated among the 7 analyzed variables. Leg and vertical stiffness in treadmill running of moderate pace (4.44 m/s) should be considered symmetric., (Copyright © 2015 Elsevier B.V. All rights reserved.)