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- Sandamas, Paul Nicolas
(författare)
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Athletic Sprint Start Biomechanics : Investigations into the relationships between three dimensional starting technique, first step width and performance
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The block and early acceleration phase plays a very important role in the overall outcome of athletic sprint events. During this part of the race it is commonly observed that sprinters use a lower-body technique that involves the swing leg crossing medially in front of the athlete followed by wide steps. These wide initial steps give the impression that the legs are flailing out to the side. Some coaches believe that this action could be inefficient and thus should be curtailed. However, there is limited knowledge about this movement pattern and its relation to performance.Therefore, the overall aim of this thesis was to help elucidate from a biomechanical perspective a) the fundamental underlying kinematic and mechanical basis to this technique and b) how both performance and muscular contributions to propulsion would be affected when step width was restricted.A cross sectional study design was used to examine specific kinematic and kinetic variables from 11 competitive sprinters (9 male, 2 female) performing maximum effort 15 m sprint starts. Three-dimensional kinematics, ground reaction force and electromyographical data were recorded from the block phase to the end of the 1st stance phase. Each athlete performed five trials with their natural technique and five trials inside a 0.3 m wide lane. A 15-segment, full-body model and a 37 degrees of freedom full-body musculoskeletal model were created and used to calculate relevant variables/parameters. Normalised average horizontal external power was used as the performance measure.A combination of pelvis list and rotation (but not hip adduction) was found to be coupled with the thigh of the swing leg moving medially during the single push phase. In the unrestricted width trials, pelvic list range of motion and medial impulses correlated positively with step width but step width was not found to be related to performance. When step width was restricted, a more forward pointing normalised average ground reaction force vector was seen but lower body muscular contributions to acceleration were reduced and no immediate improvement to performance was found.The primary kinematic reason behind the lower body posture the sprinters adopt during the block phase whereby the swing leg moves medially in front of the body is caused by a combination of three dimensional pelvis rotations rather than simply hip internal rotation/or adduction of the swing leg. Trying to reduce pelvic range of motion or minimising the flailing leg motion is unlikely to lead to an improvement in performance. Therefore, the notion that this technique is inefficient, was not supported by this study.
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- Sandamas, Paul, et al.
(författare)
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The effect of a reduced first step width on starting block and first stance power and impulses during an athletic sprint start.
- 2019
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Ingår i: Journal of Sports Sciences. - : Taylor & Francis. - 0264-0414 .- 1466-447X. ; 37:9, s. 1046-1054
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated how manipulating first step width affects 3D external force production, centre of mass (CoM) motion and performance in athletic sprinting. Eight male and 2 female competitive sprinters (100m PB: 11.03 ± 0.36 s male and 11.6 ± 0.45 s female) performed 10 maximal effort block starts. External force and three-dimensional kinematics were recorded in both the block and first stance phases. Five trials were performed with the athletes performing their preferred technique (Skating) and five trials with the athletes running inside a 0.3 m lane (Narrow). By reducing step width from a mean of 0.31 ± 0.06 m (Skating) to 0.19 ± 0.03 m (Narrow), reductions were found between the two styles in medial block and medial 1st stance impulses, 1st stance anterior toe-off velocity and mediolateral motion of the CoM. No differences were found in block time, step length, stance time, average net resultant force vector, net anteroposterior impulse nor normalised external power. Step width correlated positively with medial impulse but not with braking nor net anteroposterior impulse. Despite less medially directed forces and less mediolateral motion of the CoM in the Narrow trials, no immediate improvement to performance was found by restricting step width.
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- Sandamas, Paul, et al.
(författare)
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The relationships between pelvic range of motion, step width and performance during an athletic sprint start
- 2020
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 38:19, s. 2200-2207
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were (a) to describe the kinematics underlying the phenomenon of the knee of the swing leg passing medially in front of the athlete during the single push (SP) phase of the block sprint start, and (b) to determine the relationships between block phase pelvis range of motion (RoM), 1st step width and block phase performance. Three-dimensional kinematic data (250 Hz) were collected from eleven competitive sprinters (100 m PB: 11.17 ± 0.41) performing maximal effort block starts. The joint angles of the rear hip with respect to the pelvis and the pelvis segment angles with respect to the laboratory coordinate system were calculated during the block start phase to the end of the 1st stance. A combination of pelvis list and rotation (not hip adduction) was coupled with the thigh of the swing leg moving medially during the SP phase. A very high positive correlation was found between pelvic list RoM and 1st step width (r = 0.799, p = 0.003). No other significant correlations were found. Attempting to reduce pelvic RoM or changing frontal and transverse plane hip joint angles to minimise medial thigh motion is unlikely to lead to an improvement to performance.
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- Wang, Ruoli, et al.
(författare)
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The Effect of Step Width on Muscle Contributions to Body Mass Center Acceleration During the First Stance of Sprinting
- 2021
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media S.A.. - 2296-4185. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: At the beginning of a sprint, the acceleration of the body center of mass (COM) is driven mostly forward and vertically in order to move from an initial crouched position to a more forward-leaning position. Individual muscle contributions to COM accelerations have not been previously studied in a sprint with induced acceleration analysis, nor have muscle contributions to the mediolateral COM accelerations received much attention. This study aimed to analyze major lower-limb muscle contributions to the body COM in the three global planes during the first step of a sprint start. We also investigated the influence of step width on muscle contributions in both naturally wide sprint starts (natural trials) and in sprint starts in which the step width was restricted (narrow trials).Method: Motion data from four competitive sprinters (2 male and 2 female) were collected in their natural sprint style and in trials with a restricted step width. An induced acceleration analysis was performed to study the contribution from eight major lower limb muscles (soleus, gastrocnemius, rectus femoris, vasti, gluteus maximus, gluteus medius, biceps femoris, and adductors) to acceleration of the body COM.Results: In natural trials, soleus was the main contributor to forward (propulsion) and vertical (support) COM acceleration and the three vasti (vastus intermedius, lateralis and medialis) were the main contributors to medial COM acceleration. In the narrow trials, soleus was still the major contributor to COM propulsion, though its contribution was considerably decreased. Likewise, the three vasti were still the main contributors to support and to medial COM acceleration, though their contribution was lower than in the natural trials. Overall, most muscle contributions to COM acceleration in the sagittal plane were reduced. At the joint level, muscles contributed overall more to COM support than to propulsion in the first step of sprinting. In the narrow trials, reduced COM propulsion and particularly support were observed compared to the natural trials.Conclusion: The natural wide steps provide a preferable body configuration to propel and support the COM in the sprint starts. No advantage in muscular contributions to support or propel the COM was found in narrower step widths.
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