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Effect of postural changes on 3D joint angular velocity during starting block phase a
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Jean Slawinski , Raphaël Dumas , Laurence Cheze , Guy Ontanon , Christian Miller & Alice Mazure–Bonnefoy
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University Paris Ouest Nanterre La Défense, UFRSTAPS – Centre de Recherche sur le Sport et le Mouvement, EA2931, 200 Avenue de la République, Nanterre, 92000, France b
Université Lyon 1, IFSTTAR, UMR-T9406 Laboratoire de Biomécanique et Mécanique des Chocs, Lyon, France c
Team Lagardère, Centre d’Expertise, 26 Avenue du Général Sarrail, Paris, France
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Hôpital Cantonal de Genève, Genève, Switzerland
Version of record first published: 12 Oct 2012.
To cite this article: Jean Slawinski, Raphaël Dumas, Laurence Cheze, Guy Ontanon, Christian Miller & Alice Mazure–Bonnefoy (2012): Effect of postural changes on 3D joint angular velocity during starting block phase, Journal of Sports Sciences, DOI:10.1080/02640414.2012.729076 To link to this article: http://dx.doi.org/10.1080/02640414.2012.729076
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Journal of Sports Sciences, 2012; 1–8, iFirst article
Effect of postural changes on 3D joint angular velocity during starting block phase
¨ L DUMAS2, LAURENCE CHEZE2, GUY ONTANON3, JEAN SLAWINSKI1, RAPHAE 3 CHRISTIAN MILLER , & ALICE MAZURE–BONNEFOY4
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University Paris Ouest Nanterre La De´fense, UFRSTAPS - Centre de Recherche sur le Sport et le Mouvement EA2931, 200 Avenue de la Re´publique, Nanterre, 92000 France, 2Universite´ Lyon 1, IFSTTAR, UMR-T9406 Laboratoire de Biome´canique et Me´canique des Chocs, Lyon, France, 3Team Lagarde`re, Centre d’Expertise, 26 Avenue du Ge´ne´ral Sarrail, Paris, France, and 4Hoˆpital Cantonal de Gene`ve, Gene`ve, Switzerland (Accepted 7 September 2012)
Abstract Few studies have focused on the effect of posture during sprint start. The aim of this study was to measure the effect of the modification of horizontal distance between the blocks during sprint start on three dimensional (3D) joint angular velocity. Nine trained sprinters started using three different starting positions (bunched, medium and elongated). They were equipped with 63 passive reflective markers, and an opto-electronic Motion Analysis1 system was used to collect the 3D marker trajectories. During the pushing phase on the blocks, norm of the joint angular velocity (NJAV), 3D Euler angular velocity (EAV) and pushing time on the blocks were calculated. The results demonstrated that the decrease of the block spacing induces an opposite effect on the angular velocity of joints of the lower and the upper limbs. The NJAV of the upper limbs is greater in the bunched start, whereas the NJAV of the lower limbs is smaller. The modifications of NJAV were due to a combination of the movement of the joints in the different degrees of freedom. The medium start seems to be the best compromise because it leads, in a short pushing time, to a combination of optimal joint velocities for upper and lower segments.
Keywords: biomechanics, running, performance, sprint
Introduction Nowadays, the optoelectronic tracking systems are largely used to analyse the three dimensional (3D) kinematics of the body segments in various research fields as clinical applications or sport analyses. Concerning the sport analyses and more particularly the sprint start, the two dimensional (2D) kinematics have been generally analysed (Baumann, 1976; Bezodis, Kerwin, & Salo, 2008; Bezodis, Salo, & ˇ oh, Josˇt, Sˇkof, Tomazˇin, & Trewartha, 2010; C Dolenec, 1998; Harland & Steele, 1997; Hunter, Marshall, & McNair, 2004; Jacobs & van Ingen Schenau, 1992; Johnson & Buckley, 2001; Mero, Luhtanen, & Komi, 1983). If 2D analysis allows us to understand the key kinetic and kinematic characterˇ oh, et al., 1998; Harland istics of the performance (C & Steele, 1997; Mero et al., 1983), it appears that the 3D models are more relevant to analyse the body organisation (i.e. in terms of joint velocities) during
this specific, fast and complex movement. Our previously published work (Slawinski et al., 2010) showed that, during the starting block phase, the use of the norm of joint angular velocities allows the quantification of the maximal 3D angular velocity of joint opening. The Euler angular velocity completes this analysis by showing which movement (i.e. flexion/ extension; internal and external rotations and adduction/abduction) produces the norm of joint angular velocities. Both parameters describe precisely the technical organisation of the movement of the sprinter and are of interest for coaches and their athletes to identify areas of improvement. This particular phase of the race can be optimised by the runner thanks to the modification of the horizontal distance between the blocks. There is the bunched start (spacing generally 530 cm), the medium start (30 to 50 cm) and the elongated start (450 cm) (Harland & Steele, 1997). Numerous studies were interested in the influence of the
Correspondence: Jean Slawinski, University Paris Ouest Nanterre La De´fense, UFRSTAPS - Centre de Recherche sur le Sport et le Mouvement EA2931, 200 Avenue de la Re´publique, Nanterre, 92000 France. E-mail:
[email protected] ISSN 0264-0414 print/ISSN 1466-447X online Ó 2012 Taylor & Francis http://dx.doi.org/10.1080/02640414.2012.729076
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horizontal distance modification between the blocks but focused their analysis on the velocity of the centre of mass, the time taken to reach a specific distance, the instantaneous sprinter velocity at a specific distance or events (Salo & Bezodis, 2004; Bezodis et al., 2010; Cronin, Green, Levin, Brughelli, & Frost, 2007; Dickinson, 1934; Duthie, Pyne, Ross, Livingstone, & Hooper, 2006; Frost, Cronin, & Levin, 2008; Kisler, 1934; Kraan, van Veen, Snijders, & Storm, 2001; Schot & Knutzen, 1992; Sigerseth & Grinaker, 1962). Recently, using a 3D kinematic approach to analyse the bunched, medium and elongated start (Slawinski et al., 2012), we confirmed the results obtained by these authors. Indeed, we showed that the elongated start induced an increase of the centre of mass velocity associated with an increase of the pushing time on the block. Moreover, this previous work demonstrated the major role of kinetic energy of the head-neck, thorax, abdomen and pelvis segments in the increase of the centre of mass velocity. Nevertheless, the specific role of the joint angular velocities, i.e. how the joints begin to move and at which speed, linked to the modification of the horizontal distance between the blocks, remains unknown. Thus, the aim of the present study was to use the relevance of the norm of joint angular velocities and the Euler angular velocity in order to analyse postural adaptation of well-trained sprinters due to the three different horizontal distances between the blocks (bunched, medium and elongated). According to our previous work (Slawinski et al., 2010), we firstly hypothesised that the modification of the horizontal distance between the blocks will induce a modification of the norm of joint angular velocities. Greater norm of joint angular velocities relates to faster sprint start. Secondly, although the modification in initial posture mainly relates to the sagittal plane, Euler angular velocity changed for the three degrees of freedom.
starting blocks. A first horizontal adjustment corresponded to the bunched start (the inter-block spacing was 21.5 + 3.2 cm). A second horizontal adjustment corresponded to the medium start (the inter-block spacing was 36.8 + 3.5 cm). A third horizontal adjustment corresponded to the elongated start (the horizontal inter-block spacing was 54.8 + 3.8 cm). In order to take into account the size of each runner, they were free to choose their preferred distance between the blocks for each starting condition (bunched, medium and elongated). Moreover, to be sure that they made the right choice of the distance between the blocks, they had a period of training of two weeks before the experimental session. Each starting condition was repeated three times, thus each sprinter realised a total of nine maximal 10 m sprint starts. Each of the three starting conditions was randomised for each athlete. The horizontal inter-block spacing and distance from the starting line were adjusted individually. The blocks’ obliquity was the same for each condition. The distance from the starting line was 55.5 + 6.3 cm. An opto-electronic Motion Analysis1 system consisting of 12 digital cameras (250 Hz) was used to record the 3D marker trajectories. The participant was equipped with 63 passive reflective markers (Figure 1). The markers were glued to the skin and assumed to follow the movement of the bony landmarks. The markers were placed on points that are easily identifiable on all participants, as close as possible to the bony parts of the segments. This is
Material and methods Participants Nine trained sprinters (21.1 + 2.7 years old) with three women (169.0 + 2.6 cm; 57.7 + 3.8 kg) and six men (180.3 + 7.2 cm; 74.7 + 6.9 kg) took part in this study. Their best time over 100 m ranged between 11.61 + 0.42 s for the women and 10.58 + 0.27 s for the men. This study conforms to the recommendations of the Declaration of Helsinki, and had been approved by the local Ethics Committee. Procedures The sprinters started using three different horizontal inter-block spacing on an indoor track with standard
Figure 1. Position of anatomical landmarks in initial static position. The names of the anatomical landmarks are detailed in Slawinski et al. (2010).
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3D joint angular velocity and starting block phase required in order to minimise the influence of the soft tissues that may result in movement errors from the skin, muscle and fat tissues. The 3D trajectories of the passive reflective markers were computed and then corrected by a low-pass filter (Butterworth, fourth-order, with a cut-off frequency of 12 Hz). A segment coordinate system was defined on each body segment based on the markers. The orientation of their axes was carefully carried out using the International Society of Biomechanics (ISB) recommendations (Wu et al., 2002, 2005). Sixteen segments were defined. The origin of the inertial coordinate system was placed on the middle of the start lane. The rotation sequence proposed by the ISB to describe the lower and the upper segments joint movements was used. For this study, rear and front joints were respectively associated with the side of the rear and the front legs in the starting blocks. These joints are: the thoracic (movement of the thorax versus the abdomen segment), the rear and front shoulders (movement of the arm versus the thorax segment), elbows (movement of the forearm versus the arm segment), hips (movement of the thigh versus the pelvis segment), knees (movement of the leg versus the thigh segment) and ankles (movement of the foot versus the leg segment). Three degrees of freedom (flexion/extension; internal and external rotations and adduction/abduction) have been considered for each joint with the exception of the thoracic joint where only one degree of freedom (flexion/extension) has been calculated. Data analysis Time. The instant (expressed in s) of block clearing (Cblock) and the instant of clearing of the first step (Cfirst step) were measured with the opto-electronic Motion Analysis1 system. Norm of the 3D joint angular velocity and Euler angular velocity. The norm of the joint angular velocities, norm of joint angular velocities, k~ Oi=i 1k were computed from proximal and distal ~i ¼ O ~i O ~ 1. segment angular velocities: O i0 i 1 0 These segment angular velocities are obtained ~i from the skew matrix of the angular velocity O 0 available in the 3D velocity matrix of the proximal and distal segments computed using the homogenous matrix algebra: 1 ~i ~i ðOi Þ O V W0i ¼ ¼ T_ 0i T0i 0 0 0 0 0 0 1 with T0i the inverse matrix and T_ 0i the first order derivative of the matrix T0i (computed using a centred fourth-order finite difference followed by a low-pass filtering).
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Moreover, the matrix Ti=0 defined the orientation and the position of ith SCS (segment coordinate system) with respect to an inertial coordinate system and is calculated from the 3D trajectories of the passive reflective markers. From the norm of joint angular velocities, the maximal values of the norm of joint angular velocities were calculated to analyse the data. To know which degree of freedom (flexion/extension, adduction/abduction or internal/external rotation) is more important during the movement, the Euler Angular Velocity was used, in addition to the numerical value of norm of joint angular velocities. For this, the joint angular velocity was projected on each axis of the joint coordinate system in order to _ g_ Þ: _ b; derive the Euler angles derivatives ða; ! ! ! ~ 1 ¼ ðe2 e3 Þ O i=i 1 ! Oi=i e1 ! ! ðe! 1 e2 Þ e3 |fflfflfflfflfflfflfflfflfflffl{zfflfflfflfflfflfflfflfflfflffl} a_
! ! ! ! ðe! ðe! 3 e1 Þ O i=i 1 ! 1 e2 Þ O i=i 1 ! þ e2 þ e3 ! ! ! ! ðe! ðe! 1 e2 Þ e3 1 e2 Þ e3 |fflfflfflfflfflfflfflfflfflffl{zfflfflfflfflfflfflfflfflfflffl} |fflfflfflfflfflfflfflfflfflffl{zfflfflfflfflfflfflfflfflfflffl} b_
g_
where a_ could be interpreted as flexion/extension angle (about ! e1 , axis from joint coordinate system), b_ could be interpreted as internal/external rotation (about ! e3 axis, from joint coordinate system) and g_ could be interpreted as abduction/adduction angle (about ! e2 ¼ ! e3 ! e1 ). ! e1 is a selected axis from the matrix Ti1=0 , ! e3 is a selected axis from the matrix Ti=0 and ! e3 ! e1 . e2 ¼ ! This procedure was preferred to the classical computation of the Euler angles than can be prone to singularity and discontinuity. Moreover, by using this procedure, all the results are uniformly obtained from the same angular velocity computations. Statistical analyses All data are presented as means plus or minus standard deviations (s). After a normality test, comparison of the data between bunched, medium and elongated start was performed using a Friedman test. A Dunn post-hoc test was performed in order to find significant differences between bunched, medium or elongated conditions. All statistical analyses were conducted at P 5 0.05. Results The modification of the inter-block spacing has a significant effect on Cblock and Cfirst step (P 0.001). Cblock was significantly greater in the elongated start compared to the bunched and medium start
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J. Slawinski et al. modifications of the distance between the blocks have no significant effect on the thoracic, elbow or ankle joint. The maximal values of the norm of joint angular velocities of the rear shoulder are greater in the bunched and medium start compared to the elongated start (respectively for elongated, medium and bunched, 554.6 + 56.4; 605.9 + 58.4; 624.9 + 50.2 deg s71). The Euler angular velocity of this joint was significantly increased for the movement of flexion/extension and of internal/ external rotation (Figure 2).
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(respectively for elongated, medium and bunched, 0.414 + 0.023; 0.377 + 0.017 and 0.371 + 0.016 s). The same results were obtained for Cfirst step. Indeed, it was significantly greater later in the elongated start compared to bunched and medium start (respectively for elongated, medium and bunched, 0.666 + 0.024; 0.632 + 0.021 and 0.628 + 0.018 s). The main significant results are presented in this section i.e. those relating to the rear shoulder, the rear and front hips and the rear knee. The
Figure 2. Norm of joint angular velocities of the rear shoulder (A), and its Euler angular velocity with the three degrees of freedom, flexion/ extension (B), adduction/abduction (C) and internal/external rotation (D). The positive part of the curves (B, C and D) is associated with a movement of flexion, adduction and internal rotation. The negative part of these curves represents movement of extension, abduction and external rotation. {Significant effect of the inter-block spacing (analysis of variance [ANOVA]).
3D joint angular velocity and starting block phase
elongated, medium and bunched, 339.1 + 52.6; 358.8 + 52.6; 313.4 + 55.0 deg s71). The Euler angular velocity of this joint was significantly decreased for the movement of flexion/extension and of adduction/abduction (Figure 4). The maximal values of the norm of joint angular velocities of the rear knee are smaller in the bunched start compared to the medium and elongated start (respectively for elongated, medium and bunched, 659.9 + 85.0; 608.1 + 83.8; 447.5 + 70.6 deg s71). The Euler angular velocity of this
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The maximal values of the norm of joint angular velocities of the front hip are smaller in the bunched start compared to the elongated start (respectively for elongated, medium and bunched, 420.9 + 41.7; 381.1 + 40.6; 366.6 + 39.7 deg s71). The Euler angular velocity of this joint was significantly decreased for the movement of flexion/extension and of abduction/adduction (Figure 3). The maximal values of the norm of joint angular velocities of the rear hip are smaller in the bunched start compared to the medium start (respectively for
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Figure 3. Norm of joint angular velocities of the front hip (A), and its Euler angular velocity with the three degrees of freedom, flexion/ extension (B), adduction/abduction (C) and internal/external rotation (D). The positive part of the curves (B, C and D) is associated with a movement of flexion, abduction and external rotation. The negative part of these curves represents movement of extension, adduction and internal rotation. {Significant effect of the inter-block spacing (ANOVA).
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Figure 4. Norm of joint angular velocities of the rear hip (A), and its Euler angular velocity with the three degrees of freedom, flexion/ extension (B), adduction/abduction (C) and internal/external rotation (D). The positive part of the curves (B, C and D) is associated with a movement of flexion, adduction and internal rotation. The negative part of these curves represents movement of extension, abduction and external rotation. {Significant effect of the inter-block spacing (ANOVA).
joint was significantly decreased for the movement of flexion/extension and of internal/external rotation (Figure 5). Discussion In order to optimise the sprint start, the unique exterior factor that the athletes can modify is the block position (spacing or obliquities). These modifications involve different postural adaptations of the body segments. To analyse the body organisation during this specific and complex movement, the 3D
models combined with the norm of joint angular velocities and the Euler angular velocity are useful tools (Slawinski et al., 2010). Thus, the aim of this study was to use the relevance of the norm of joint angular velocities and the Euler angular velocity in order to analyse postural adaptation of well-trained sprinters due to the three different horizontal distances between the blocks (bunched, medium and elongated). From a global approach of the body organisation, the results demonstrated that of the 11 joints analysed, the norm of joint angular velocities of
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3D joint angular velocity and starting block phase
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Figure 5. Norm of joint angular velocities of the rear knee (A), and its Euler angular velocity with the two degrees of freedom, flexion/ extension (B) and adduction/abduction (C). The positive part of the curves (B and C) is associated with a movement of extension and internal rotation. The negative part of these curves represents movement of flexion and external rotation {Significant effect of the inter-block spacing (ANOVA).
only four of them were significantly influenced by the modifications of the horizontal distances between the blocks. These joints were: the rear shoulder, the front and rear hips and the rear knee. More detailed analysis of the results show that the effect of the horizontal distance between the blocks on the maximal values of the norm of joint angular velocities is different for the upper segments’ joints (rear shoulder) and the lower segments’ joints (front hip and rear hip and knee). Indeed, in the elongated start, the maximal values of the norm of joint angular velocities of the upper limb joint decreased and the maximal values of the norm of joint angular velocities of the lower segment joints increased. Inversely, in the bunched start, the maximal values of the norm of joint angular velocities of the upper limb joint increased and the maximal values of the norm of joint angular velocities of the lower segment joints decreased. These results could be explained by the decrease of the lower limbs’ propulsion in the bunched condition. Indeed, Kraan et al. (2001) demonstrated that the reduction of the distance between the feet during start also reduced the force and power developed by the participants. Moreover, it appears
that the lower norm of joint angular velocities developed by the lower limbs is associated with a combination of different degrees of freedom. Indeed, the analysis showed, during the bunched start, the Euler angular velocity was decreased for the front hip extension and abduction (Figure 3), the flexion and adduction of the rear hip (Figure 4) and the flexion, and the variation between external and internal rotation of the rear knee (Figure 5). Contrary to the lower limb joints, in the bunched condition, the rear shoulder develops an important velocity associated with a greater Euler angular velocity in extension and in external rotation movements (Figure 2). Indeed, the sprinter must balance, in a short time, the role of the rear lower segments in the forward direction with a quick backward movement of the rear shoulder using the three space planes. Hence, at the instant of the start, the sprinter uses his rear shoulder in order to balance, to conserve his equilibrium and to prepare the first step of the race (Bhowmick & Bhattacharyya, 1988). Finally, concerning the medium start, it is interesting to note that the maximal values of the norm of joint angular velocities of the upper and lower limb joints are not significantly modified but that this one
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is always nearer of the greatest the maximal values of the norm of joint angular velocities measured for the others conditions. Thus, with the medium start, the athletes seems to be able to move their upper and lower body segments with the optimal norm of joint angular velocities at the same time and not over another joint as for the bunched or elongated start. Therefore, the medium start seems to be the best compromise in terms of technical organisation of the movement, because it leads to a combination of the optimal joint velocities for upper and lower segments. These upper and lower joint velocities could explain why the medium start is also the best compromise between the three types of starts. Indeed, the results demonstrated that, if in the bunched start the sprinters have the shortest pushing time (shortest Cblock and Cfirst step), the pushing time of the medium start is slightly longer but not significantly different from the bunched start. Hence, the athletes do not lose time with the medium start. A way to improve the efficiency of the starting phase could be to improve upper and lower joint velocity in order to decrease the pushing time on the ground. Conclusion The results confirm our hypothesis, and demonstrated that the modification of the block spacing modifies the norm of joint angular velocities of the upper and lower limbs. When the block spacing is modified an opposite effect on the norm of joint angular velocities of the lower and upper limbs is observed concerning the bunched and elongated starts. Moreover, as hypothesised, these modifications of norm of joint angular velocities of upper and lower limbs were due to a modification of the Euler angular velocity in the different degrees of freedom and not only of a flexion/extension component. It appears that the medium start seems to be the best compromise, despite the absence of significant results, in terms of norm of joint angular velocities, technical organisation of the movement and pushing time. References Baumann, W. (1976). Kinematic and dynamic characteristics of the sprint start. In P.V. Komi (Ed.), Biomechanics V-B (pp. 194–199). Baltimore, MD: University Park Press. Bezodis, I., Kerwin, D., & Salo, A. (2008). Lower-limb mechanics during the support phase of maximum-velocity sprint running. Medicine and Science in Sports and Exercise, 40, 707–715. Bezodis, N., Salo, A., & Trewartha, G. (2010). Choice of sprint start performance measure affects the performance-based ranking within a group of sprinters: Which is the most appropriate measure? Sports Biomechanics, 9, 258–269. Bhowmick, S., & Bhattacharyya, A.K. (1988). Kinematic analysis of arm movements in sprint start. Journal of Sports Medicine and Physical Fitness, 28, 315–323.
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