Practitioners have, for many years, argued that athletic sprinters should optimize front-side mechanics (leg motions occurring in front of the extended line through the torso) and minimize back-side mechanics. This study aimed to investigate if variables related to front- and back-side mechanics can be distinguished from other previously highlighted kinematic variables (spatiotemporal variables and variables related to segment configuration and velocities at touchdown) in how they statistically predict performance. A total of 24 competitive sprinters (age: 23.1 [3.4] y, height: 1.81 [0.06] m, body mass: 75.7 [5.6] kg, and 100-m personal best: 10.86 [0.22] s) performed two 20-m starts from block and 2 to 3 flying sprints over 20 m. Kinematics were recorded in 3D using a motion tracking system with 21 cameras at a 250 Hz sampling rate. Several front- and back-side variables, including thigh (r = .64) and knee angle (r = .51) at lift-off and maximal thigh extension (r = .66), were largely correlated (P < .05) with accelerated running performance, and these variables displayed significantly higher correlations (P < .05) to accelerated running performance than nearly all the other analyzed variables. However, the relationship directions for most front- and back-side variables during accelerated running were opposite in comparison to how the theoretical concept has been described. Horizontal ankle velocity, contact time, and step rate displayed significantly higher correlation values to maximal velocity sprinting than the other variables (P < .05), and neither of the included front- and back-side variables were significantly associated with maximal velocity sprinting. Overall, the present findings did not support that front-side mechanics were crucial for sprint performance among the investigated sprinters.
Haugen and Alnes are with the Dept of Training & Testing, Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway. Danielsen, McGhie, Sandbakk, and Ettema are with the Dept of Neuroscience, Center for Elite Sports Research, Norwegian University of Science and Technology, Trondheim, Norway.
MorinJB, EdouardP, SamozinoP. Technical ability of force application as a determinant factor of sprint performance. Med Sci Sports Exerc. 2011;43:1680–1688. PubMed doi:10.1249/MSS.0b013e318216ea3710.1249/MSS.0b013e318216ea3721364480)| false
RabitaG, DorelS, SlawinskiJ, et al. Sprint mechanics in world-class athletes: a new insight into the limits of human locomotion. Scand J Med Sci Sports. 2015;25:583–594. PubMed doi:10.1111/sms.1238910.1111/sms.1238925640466)| false
BradshawEJ, MaulderPS, KeoghJW. Biological movement variability during the sprint start: performance enhancement or hindrance?Sports Biomech. 2007;6:246–260. PubMed doi:10.1080/147631407014896601793319010.1080/14763140701489660)| false
BezodisNE, SaloAI, TrewarthaG. Lower limb joint kinetics during the first stance phase in athletics sprinting: three elite athlete case studies. J Sports Sci. 2014;32:738–746. PubMed doi:10.1080/02640414.2013.849000
BezodisNE, SaloAI, TrewarthaG. Lower limb joint kinetics during the first stance phase in athletics sprinting: three elite athlete case studies. J Sports Sci. 2014;32:738–746. PubMed doi:10.1080/02640414.2013.84900010.1080/02640414.2013.84900024359568)| false
BezodisNE, SaloAI, TrewarthaG. Relationships between lower-limb kinematics and block phase performance in a cross section of sprinters. Eur J Sport Sci. 2015;15:118–124. PubMed doi:10.1080/17461391.2014.928915
BezodisNE, SaloAI, TrewarthaG. Relationships between lower-limb kinematics and block phase performance in a cross section of sprinters. Eur J Sport Sci. 2015;15:118–124. PubMed doi:10.1080/17461391.2014.92891510.1080/17461391.2014.928915)| false
BushnellT, HunterI. Differences in technique between sprinters and distance runners at equal and maximal speeds. Sports Biomech. 2007;6:261–268. PubMed doi:10.1080/147631407014897281793319110.1080/14763140701489728)| false
NagaharaR, NaitoH, MorinJB, ZushiK. Association of acceleration with spatiotemporal variables in maximal sprinting. Int J Sports Med. 2014;35:755–761. PubMed doi:10.1055/s-0033-13632522457786410.1055/s-0033-1363252)| false
EttemaG, McGhieD, DanielsenJ, SandbakkØ, HaugenT. On the existence of step-to-step breakpoint transitions in accelerated sprinting. PLoS ONE.2016;11:0159701. doi:10.1371/journal.pone.015970110.1371/journal.pone.0159701)| false
BezodisNE, TrewarthaG, SaloAI. Understanding the effect of touchdown distance and ankle joint kinematics on sprint acceleration performance through computer simulation. Sports Biomech. 2015;14:232–245. PubMed doi:10.1080/14763141.2015.1052748
International Association of Athletics Federations (IAAF). Competition rules 2018–2019. https://www.iaaf.org/about-iaaf/documents/technical#collapsemanuals-guidelines. Accessed November 1, 2017.)| false
HopkinsWG, MarshallSW, BatterhamAM, HaninJ. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc. 2009;41:3–13. PubMed doi:10.1249/MSS.0b013e31818cb2781909270910.1249/MSS.0b013e31818cb278)| false
ChenP, PopovichP. Correlation: Parametric and Nonparametric Measures. Thousand Oaks, CA: Sage; 2002:7–139. Sage University Paper Series on Quantitative Applications in the Social Sciences.10.4135/9781412983808)| false