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Ground Force Direction for Optimal Performance Using a Standing Start. Both the moving start and variations of the standing start are utilized in baseball, basketball, soccer, field hockey, lacrosse, rugby and other sports. Athletes who either lack the strength needed for the forceful push off both feet required during the 3- or 4-point starting stance, or have not mastered the correct form and technique, can often improve their times in a short sprint by utilizing a standing start. This also places the front foot closer to the starting line, is more forgiving, easier to master, and moves the body into the correct sprint position within the first two steps with less ground reaction force than what is required from a crouched position. The study described below examined the connection between ground reaction impulses and sprint acceleration when the standing start was used and offers training advice for the improvement of horizontally-directed ground reaction force.
Large horizontal acceleration in short sprints is a critical performance parameter for many team sports athletes. It is often stated that producing large horizontal impulse at each ground contact is essential for high short sprint performance, but the optimal pattern of horizontal and vertical impulses is not well understood, especially when the sprints are initiated from a standing start.
This study was an investigation of the relationships between ground reaction impulses and sprint acceleration performance from a standing start in team sports athletes. Thirty physically active young men with team sports backgrounds performed 10-m sprints from a standing start, whereas sprint time and ground reaction forces were recorded during the ﬁfirst ground contact and at 8 m from the start. Associations between sprint time and ground reaction impulses (normalized to body mass) were determined by a Pearson’s correlation coefﬁcient (r) analysis. The 10-m sprint time was signiﬁcantly ( p 0.01) correlated with net horizontal impulse (r =20.52) and propulsive impulse (r =20.66) measured at 8 m from the start. No signiﬁcant correlations were found between sprint time and impulses recorded during the ﬁrst ground contact after the start. These results suggest that applying ground reaction impulse in a more horizontal direction is important for sprint acceleration from a standing start. This is consistent with the hypothesis of training to increase net horizontal impulse production using sled towing or using elastic resistance devices, which needs to be validated by future longitudinal training studies.
Increasing ground reaction force in a horizontal direction, using the Austin leg-drive machine, weighted sleds, and band resistance, is recommended to improve speed in the standing start and early acceleration phase of a short sprint.
Naoki Kawamori, Kazunori Nosaka, and Robert U. Newton. 2013. Relationships between ground reaction impulse and sprint acceleration performance in team sport athletes. Journal of strength and Conditioning research 27(3)568-573.
A grounded perspective on human running: The information below provides accurate responses to two key questions about speed improvement from Dr. Peter Weyand, one of the leading researchers in the world on this topic. A careful read will result in a better understanding of how speed can be improved for sports competition, including two-mass model, spring-mass model, impact-deceleration, contact time, aerial time, swing time.
Sprint running performance can be investigated relatively simply at the whole-body level by examining the timing of the phases of the stride and the forces applied to the ground in relation to a runners body weight. Research using this approach has been used to address a number of basic questions regarding the limits and determinants of human running speed. The primary differentiating factor for the top speeds of human runners is how forcefully they can strike the ground in relation to body mass. A general relationship between mass-specific force application and maximum running speeds results from from the similar durations of the aerial and swing phases of the stride for different runners. Recent work has elucidated the mechanism by which faster runners are able to apply greater mass-specific ground forces in the very brief foot-ground contact times sprinting requires.
INTRODUCTION: The primary requirement of human locomotion is supporting the body’s weight against gravity. This requirement has provided insights into locomotor metabolism (Kram & Taylor, 1990; Roberts et al, 1998; Taylor, 1985), gait mechanics (Blickhan , 1989; Weyand et al., 2001) and the sprinting performance of humans (Kuitunen et al., 2002; Rabita et al., 2015) and other animal runners (Taylor, 1980). During steady-speed running on a level surface, the stride-averaged vertical force runners apply to the surface equals their body weight. Faster runners can satisfy this force requirement with greater forces that are applied in shorter periods of time. Consequently, the maximal speeds of human and other runners are largely explained by the maximum forces they can apply to the ground in relation to body mass (Weyand et al., 2010). Here, two questions are considered: 1) why does the general relationship between mass-specific force and top running speed exist? and 2) what is the mechanism by which faster runners are able to apply greater mass-specific ground forces?
QUESTION 1: Why does the general relationship between mass-specific force and top running speed exist? Elite human sprinters can apply peak forces to the running surface as large as 5.0 times body mass and stance-averaged forces that are as large as 2.5 times body mass. In contrast, capable, but less swift human runners typically apply peak forces of 3.5 times their body weight and stance-averaged forces of up to 2.0 times body weight (Clark & Weyand, 2014). The strength of the relationship between the mass-specific forces runners apply and how swiftly they can run at top speed results from the similar durations of the non-contact portion of the stride. At tops speed, 28 35th Conference of the International Society of Biomachanics in Sports, Cologne, Germany, June 14-18, 2017 1 Weyand: FORCE, MOTION, SPEED: A GROUNDED PERSPECTIVE ON HUMAN RUNNING PER Published by NMU Commons, 2017 fast and slow runners alike typically spend 0.12 s in the air between steps and take slightly longer than one-third of a second to reposition the limbs (Weyand et al., 2000). These observations suggest that maximizing force application may be the only viable mechanical option by which human runners can maximize speed (Clark et al., 2014).
QUESTION 2: What is the mechanism by which faster runners are able to apply greater forces to the ground? If the speeds of the swiftest human runners are largely determined by the magnitude of the massspecific forces they can apply to the ground, what confers the ability to apply relatively larger forces? Do the swiftest sprinters have intrinsically stronger limbs and limb muscles? Or, alternatively, do they use the motion of the running stride to maximize the forces applied to the ground? Recent research indicates that speed athletes exploit a motion-to-force mechanism during the impact portion of the contact period to maximize ground reaction forces applied during the brief contact periods sprinting requires (Calrk & Weyand, 2014; Clark et al., 2017). These athletes attain greater limb velocities before the foot contacts the ground. They also stop the limb more abruptly upon impact. This impact-deceleration mechanism results in a rapid rising edge of the force-time relationship and a peak force that occurs well before the mid-point of the contact period. The resulting asymmetrical pattern of force application deviates substantially from the ground force application predicted by the spring-mass model (Blickhan, 1989) indicating that the model does not include the force-motion elements responsible for sprinting performance. The variation present in the patterns of ground force application for sprinters and non-sprinters alike can be predicted from body mass and three stride-specific prameters (contact time, aerial time and ankle acceleration) using an anatomically based two-mass model of the human body. These observations indicte that sprinters exploit a motion-based deceleration mechanism to maximize ground force application. To what extent the dynamic mechanism relies on intrinsic limb strength vs. motor control and timing precision remains to be determined.
CONCLUSIONS: The conformation of both the running gait mechanics and ground reaction force patterns of human sprinters to a common pattern: 1) is further evidence that human sprinting performance is constrained by the brief duration of foot-ground force application at very fast running speeds, and 2) implies a convergence that results from the physics of motion and the properties of the tissues that generate and transmit musculoskeletal forces to the ground.
REFERENCES: Blickhan, R., “The Spring-Mass Model for Running and Hopping,” Journal of Biomechanics, vol. 22, pp. 1217- 1227, 1989. Clark, K.P. & Weyand, P.G., “Are running speeds maximized with simple-spring stance mechanics?,” Journal of Applied Physiology, vol. 117, pp. 604-615, 2014. Clark, K.P., Ryan, L.J., & Weyand, P.G., “Foot speed, foot-strike and footwear: linking gait mechanics and running ground reaction forces,” Journal of Experimental Biology, vol. 217, pp. 2037-2040, 2014. Clark, K.P., Ryan, L.J., & Weyand, P.G., “A general relationship links gait mechanics and running ground reaction forces,” Journal of Experimental Biology, vol.220, pp.247-258, 2017. Kram R. & Taylor C.R. Energetics of running: a new perspective, Nature 346(6281): 265-267,1990. Kuituen, S., Komi, P.V., & Kyrolainen, H., “Knee and ankle joint stiffness in sprint running,” Medicine and Science in Sports and Exercise, vol. 34, pp. 166-173, 2002. Rabita G., Dorel, S., Slawinski, J. Saez de Villareal, Couturier, P, Morin J.B. (2015) Sprint mechanics in worldclass athletes: new insight into the limits of human locomotion, Scandinavian Journal of Medicine and Science in Sports, 25(5): 583-594. Roberts T.J., Kram R., Weyand P.G., Taylor C.R. “Energetics of bipedal running I: energetic cost of generating force. Journal of Experimental Biology, 201(19) 2745-2751, 1998. Taylor, C.R., “Force development during locomotion: a determinant of gait, speed and metabolic power”, Journal of Experimental Biology, 115: 255-262, 1985.
Peter Weyand Locomotor Performance Laboratory, Department of Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas, USA. 35th Conference of the International Society of Biomachanics in Sports, Cologne, Germany, June 14-18, 2017
Effects of weighted sled towing on ground reaction force during the acceleration phase of sprint running: There is a need for additional research on the proper use and variable control for sprint-resisted training (weighted sleds, Austin leg-drive machine, uphill and staircase sprinting, and resistance bands) to effectively improve horizontally- and vertically-directed ground reaction force (GRF). The study described below analyzed force direction and sled weight to provide valuable information on specific training to increase horizontally directed force.
Athletes use weighted sled towing to improve sprint ability, but little is known about its biomechanics. The purpose of this study was to investigate the effect of weighted sled towing with two different loads on ground reaction force. Ten physically active men (mean ± SD: age 27.9 ± 1.9 years; stature 1.76 ± 0.06 m; body mass 80.2 ± 9.6 kg) performed 5 m sprints under three conditions; (a) unresisted, (b) towing a sled weighing 10% of body mass (10% condition) and (c) towing a sled weighing 30% of body mass (30% condition). Ground reaction force data during the second ground contact after the start were recorded and compared across the three conditions. No significant differences between the unresisted and 10% conditions were evident, whereas the 30% condition resulted in significantly greater values for the net horizontal and propulsive impulses (P < 0.05) compared with the unresisted condition due to longer contact time and more horizontal direction of force application to the ground. It is concluded that towing a sled weighing 30% of body mass requires more horizontal force application and increases the demand for horizontal impulse production. In contrast, the use of 10% body mass has minimal impact on ground reaction force.
Coaching Application: Although 10% of body mass sled resistance was ineffective, a 30% resistance required more horizontally-directed ground reaction force beginning with the second ground contact after the start. Additional weight increased the demand for horizontal impulse direction.
Naoki Kawamori, Robert Newton, and Ken Nosaka. 2014. Effects of weighted sled towing on ground reaction force during the acceleration phase of sprint running. Journal of Sports Sciences, Vol. 32, 1139-1145.
Age-Related Differences in Spatiotemporal Variables and Ground Reaction Forces During Sprinting in Boys: The age of the athlete (pre-pubescent and adolescent growth spurt periods) is a significant factor in sprint performance. The study described below by Nagahara and colleagues (2018) analyzed these and other periods of development in terms of ground reaction force application, stride rate, and sprinting speed.
Purpose: Researchers aimed to elucidate age-related differences in spatiotemporal and ground reaction force variables during sprinting in boys over a broad range of chronological ages.
Methods: Ground reaction force signals during 50-m sprinting were recorded in 99 boys aged 6.5–15.4 years. Step-to-step spatiotemporal variables and mean forces were then calculated.
Results: There was a slower rate of development in sprinting performance in the age span from 8.8 to 12.1 years compared with younger and older boys. During that age span, mean propulsive force was almost constant, and step frequency for older boys was lower regardless of sprinting phase. During the ages younger than 8.8 years and older than 12.1 years, sprint performance rapidly increased with increasing mean propulsive forces during the middle acceleration and maximal speed phases and during the initial acceleration phase.
Conclusion: There was a stage of temporal slower development of sprinting ability from age 8.8 to 12.1 years, being characterized by unchanged propulsive force and decreased step frequency. Moreover, increasing propulsive forces during the middle acceleration and maximal speed phases and during the initial acceleration phase are probably responsible for the rapid development of sprinting ability before and after the period of temporal slower development of sprinting ability.
Coaching Application: Prior to the adolescent growth spurt and the rapid increase in individual height and weight during puberty from the simultaneous release of growth hormones, thyroid hormones, and androgens resulting in additional strength and power, increases in ground reaction force (GRF) and stride rate may be absent, minimal or actually decline. During and after the growth spurt, GRF increases result in rapid improvement in sprint performances during the start, acceleration, and maximum speed phases of a short sprint. It is during this phase of development that strength and power training programs are extremely effective. Although modified strength training programs are encouraged, the pre-pubescent years are ideal for mastering proper sprinting form and technique.
References: Nagahara, Ryu/, Takai, Yohei, Haramura, Miki, Mizutani, Miral, Matsuo, Akifumi, Kanehisa, Hiroaki, and Fukunaga, Tesuo, 2018. Age-Related Differences in Spatiotemporal Variables and Ground Reaction Forces During Sprinting in Boys, Pediatric Exercise Science.
Kinetic Determinants of Reactive Strength in Highly Trained Sprint Athletes: Reactive strength involves the ability of an athlete to rapidly and efficiently change from an eccentric to a concentric contraction. For a sprinter, this involves the explosive action of the stretch-shortening cycle as GRF (ground reaction force) is applied each stride, during the pushing action away from the ground, to rapidly propel the body upward and forward. In team sports, movements that require a change of direction and the ability to rapidly move through the stretch shortening cycle are common throughout a competitive event.
The purpose of this study by Douglas, et. al. (2017) was to determine the braking and propulsive phase kinetic variables underpinning reactive strength in highly trained sprint athletes in comparison to a non-sprint trained control group. Twelve highly trained sprint athletes and twelve non-sprint trained participants performed drop jumps (DJs) from 0.25m, 0.50m and 0.75m onto a force plate. One familiarization session was followed by an experimental testing session within the same week. Reactive strength index (RSI), contact time, flight time, and leg stiffness were determined. Kinetic variables including force, power and impulse were assessed within the braking and propulsive phases. Sprint trained athletes demonstrated higher RSI versus non-sprint trained participants across all drop heights (3.02 vs 2.02; ES [±90% CL]: 3.11 ±0.86). This difference was primarily attained by briefer contact times (0.16 vs 0.22 s; ES: -1.49 ±0.53) with smaller differences observed for flight time (0.50 vs 0.46 s; ES: 0.53 ±0.58). Leg stiffness, braking and propulsive phase force and power were higher in sprint trained athletes. Very large differences were observed in mean braking force (51 vs 38 Nkg; ES: 2.57 ±0.73) which was closely associated with contact time (r ±90% CL: -0.93 ±0.05). Sprint trained athletes exhibited superior reactive strength than non-sprint trained participants. This was due to the ability to strike the ground with a stiffer leg spring, an enhanced expression of braking force, and possibly an increased utilization of elastic structures. The DJ kinetic analysis provides additional insight into the determinants of reactive strength which may inform subsequent testing and training.
Coaching Application: The findings of this current research and other studies indicate that reactive strength is an important quality for acceleration, agility, and change of direction speed.
Reference: Douglas, J, Pearson, S., Ross, a, and McGuigan, M. 2017. The Kinetic Determinants of Reactive Strength in Highly Trained Sprint Athletes. J Strength Cond Res. Sept. 11.
A New Direction to Athletic Performance: Understanding the Acute and Longitudinal Responses to Backward Running
Backward running is an activity seldom used in the training of athletes in power sports, yet this movement pattern is common for linebackers and defensive backs in football and all players in basketball, soccer, lacrosse, field hockey, tennis, and some other sports. The abstract below describes a study by Oliver, et. al (2018) that examines the value of backward sprint training.
Backward running (BR) is a form of locomotion that occurs in short bursts during many overground field and court sports. It has also traditionally been used in clinical settings as a method to rehabilitate lower body injuries. Comparisons between BR and forward running (FR) have led to the discovery that both may be generated by the same neural circuitry. Comparisons of the acute responses to FR reveal that BR is characterized by a smaller ratio of braking to propulsive forces, increased step frequency, decreased step length, increased muscle activity and reliance on isometric and concentric muscle actions. These biomechanical differences have been critical in informing recent scientific explorations which have discovered that BR can be used as a method for reducing injury and improving a variety of physical attributes deemed advantageous to sports performance. This includes improved lower body strength and power, decreased injury prevalence and improvements in change of direction performance following BR training. The current findings from research help improve our understanding of BR biomechanics and provide evidence which supports BR as a useful method to improve athlete performance. However, further acute and longitudinal research is needed to better understand the utility of BR in athletic performance programs.
Coaching Application\: In the NASE 5-Step Model, both sprint-assisted and sprint-resisted training (weighted suits, vests, or pants) includes backward sprinting that both underload and overload the lower extremities during high speed work. The drills attempt to mimic the specific movements that occur during competition in the sport. For example, strength coach, Bob Otrando, recommends that defensive backs in football end each workout with repetitions of backward sprinting to improve back pedaling skills. Training loads should be kept light enough to allow athletes to reach a high backward sprinting speed. Backward sprinting repetitions with added weight are also an important aspect of improving the speed-strength of the hamstring muscle group.
Jon Oliver, John Cronin, Craig Harrison, and Paul Winwood. , Craig, Cronin. 2018. A New Direction to Athletic Performance: Understanding the Acute and Longitudinal Responses to Backward Running. Sports Medicine May, Volume 48, Issue 5, pp 1083–1096.
Both resisted and assisted training programs are key parts of the NASE 5-Step Training Model for the speed improvement of athletes in power sports. The study by Wibowo, on the Impact of Assisted Sprinting training (AS) and Resisted Sprinting Training (RS) in Repetition Method on Improving Sprint Acceleration compared both methods for their effectiveness in improving early and late acceleration.
The purpose of this research was to determine the impact of assisted sprinting training (AS) and resisted sprinting training (RS) in repetition method on improving sprint acceleration capabilities. This research used an experimental method in the pre-test and post-test design. The research sample were twelve male collegiates track sprinters, athletic division Indonesia University of Education, Bandung. Six male collegiates track sprinters for AS and six male collegiates track sprinters for RS. It used simple random sampling. The instrument used was 30 m sprint test. After training three times per week for six week, data were obtained from pre-test and post-test processed statistically by t-test. The AS group and RS group showed significant changes on improving sprint acceleration capabilities. No significant different between AS and RS on improving sprint acceleration capabilities. In AS the increase was better than RS at a distance of 10 m from a distance of 30 m. While, in RS the increase was better than AS at a distance of 10-20 m and 20-30 m from a distance of 30 m. Accordingly, to improve acceleration at a distance 10 m use AS, while to improve acceleration at a distance of 10-20 m and 20-30 m from a distance of 30 m use RS.
Coaching Application: Although both AS and RS training improved acceleration, AS was slightly more effective during early and RS during late acceleration. The use of “contrast training” combines both AS and RS to alter motor patterns by using programs that impose demands easier (sprint-assisted training) and harder (sprint-resisted training) than the normal sprinting action during the same workout session. This approach may trick the neuromuscular system into performing at a higher level by making the task of sprinting more difficult or a bit easier than normal.
For both approaches (harder and easier), the resistance load is performed first, following by assisted training that makes sprinting an easier task. The heavy load is thought to excite the nervous system and allow for greater recruitment of motor neurons (post-activation potentiation) in the set that follows. Resisted sprints immediately follow the general warm-up and dynamic warm-up sessions. Three repetitions of maximum resisted sprints are performed, using a 2-5 minute recovery period between each. The contrast training session ends with one set of three repetitions over the same distance with no resistance or assistance. It is also acceptable to complete one resisted sprint, followed by one assisted sprint, and ending with one normal sprint. Another formula for contrast training is to complete 2-3 sets of one resisted effort, and finally a normal sprint.
Wibowo, Ricky. 2017 The Impact of Assisted Sprinting Training (AS) and Resisted Sprinting Training (RS) in Repetition Method on Improving Sprint Acceleration Capabilities. Jurnal Pendidikan Jasmani dan Olahra ga Volume 9 Nomor 1.
Hang clean and hang snatches produce similar improvements in female collegiate athletes: The study by Ayers and colleagues described in the Abstract below focused on hang clean and hang snatches to determine the training effects on the power, strength, and speed of female collegiate athletes.
Olympic weightlifting movements and their variations are believed to be among the most effective ways to improve power, strength, and speed in athletes. This study investigated the effects of two Olympic weightlifting variations (hang cleans and hang snatches), on power (vertical jump height), strength (1RM back squat), and speed (40-yard sprint) in female collegiate athletes. Twenty-three NCAA Division I female athletes were randomly assigned to either a hang clean group or hang snatch group. Athletes participated in two workout sessions a week for six weeks, performing either hang cleans or hang snatches for five sets of three repetitions with a load of 80-85% 1RM, concurrent with their existing, season-specific, resistance training program. Vertical jump height, 1RM back squat, and 40-yard sprint all had a significant, positive improvement from pre-training to post-training in both groups (p≤0.01). However, when comparing the gain scores between groups, there was no significant difference between the hang clean and hang snatch groups for any of the three dependent variables (i.e., vertical jump height, p=0.46; 1RM back squat, p=0.20; and 40-yard sprint, p=0.46). Short-term training emphasizing hang cleans or hang snatches produced similar improvements in power, strength, and speed in female collegiate athletes. This provides strength and conditioning professionals with two viable programmatic options in athletic-based exercises to improve power, strength, and speed.
Coaching Application: To improve sprinting speed, strength training exercise choices should be selected that train the movement patterns involved in sprinting, rather than the involved muscle groups. These exercises should mimic the movements that produce hip extension and involve multi-joint rather than single movements. Squats, dead lifts, lunges, step-ups and numerous variations of these weight room exercises, the Olympic Lifts, and plyometrics (hopping, jumping, and bounding) are recommended for a complete strength training program designed to increase overall strength, core strength, ground reaction force, and mass specific force (ratio of body weight/ground reaction force).
JL Ayers, M DeBeliso, TG Sevene, and KJ Adams. 2018. Hang cleans and hang snatches produce similar improvements in female collegiate athletes. Biol Sport. September: 33(3): 252-56
Predictors of Sprint Performance in Professional Rugby Players: Relative strength and power are key factors that affect the speed of athletes during the start, acceleration, and maximum speed phase of a short sprint. The Abstract of a study by Cunningham and colleagues, described below, reinforces this concept.
The ability to accelerate and attain high speed is an essential component of success in team sports; however, the physical qualities that underpin these activities remain unclear. This study aimed to determine some of the key strength and power predictors of speed with professional rugby players.
Methods: Twenty professional players were tested for speed (0-10-meter sprint and a flying 10-meter sprint), strength (3 repetitions maximum squat), lower body power countermovement jumps (CMJ, and drop jumps (DJ), reactive strength and leg spring stiffness. The strength and power variables were expressed as absolute values and relative values for analysis.
Results: Both relative strength (r=.55, P<0.05) and relative power (-.082, P<0.01) were negatively correlated with 10-meter time. Leg spring stiffness and DJ contact time were also related to the flying 10-meter time (r=.046 and 0.47 respectively, P(<0.05) while relative strength index was negatively related to both the 10-meter and flying 10-meter Tims (r=0.60 and r=0.62, P<0.05). Acceleration was significantly related to relative strength, relative power and jump height from a 40 cm DJ. Maximum velocity sprinting was significantly related to relative power, contact time, height and leg stiffness. The study provides an insight into those physical attributes that underpin sprinting performance in professional rugby union players and specifically highlights the importance of relative strength and power in the expression and development of different speed components (e.g. acceleration, maximum velocity). Coaching Application: Findings on “relative strength” reinforce the importance of acquiring a favorable ratio of Ground Reaction Force/Body Weight. Acceleration and maximum speed improve when GRF increases and/or body weight decreases. Team sport athletes should strive to become as strong as possible with minimum body fat. In the above study, absolute strength was not related to 10-meter or flying 10-meter speed. When 1RM strength was expressed relative to body mass, significant relationships wwere identified with jump height and 10-meter speed. In addition, acceleration and maximum speed are separate entities and require different training approaches to improve.
Cunningham, D.J., West, D.J., Owen, N.J., Shearer, D.A., Finn, C.V., Bracken, R.M., Crewther, B.T., Scott, P., Cook, C.J., and Kilduff, L.P. 2013. Strength and Power Predictors of Sprinting Performance in Professional Rugby Players. The Journal of Sports Medicine and Physical Fitness. 53: 1-2
The NFL Combine and Performance on the Football Field: Do high scores on the NFL Combine physical tests predict success in the NFL? Several studies have been conducted to answer these and other questions. The investigation by Kuzmits and colleagues described in the abstract below is perhaps one of the most negative.
Kuzmits and Adams investigated the correlation between National Football League (NFL) combine test results and NFL success for players drafted at three different offensive positions (quarterback, running back, and wide receiver) during a 6-year period, 1999-2004. The combine consisted of series of drills, exercises, interviews, aptitude tests, and physical exams designed to assess the skills of promising college football players and to predict their performance in the NFL. Combine measures examined in this study included 10-, 20-, and 40-yard dashes, bench press, vertical jump, broad jump, 20- and 60-yard shuttles, three-cone drill, and the Wonderlic Personnel Test. Performance criteria include 10 variables: draft order; 3 years each of salary received and games played; and position-specific data. Using correlation analysis, we find no consistent statistical relationship between combine tests and professional football performance, with the notable exception of sprint tests for running backs. We put forth possible explanations for the general lack of statistical relations detected, and, consequently, we question the overall usefulness of the combine. We also offer suggestions for improving the prediction of success in the NFL, primarily the use of more rigorous psychological tests and the examination of collegiate performance as a job sample test. Finally, from a practical standpoint, the results of the study should encourage NFL team personnel to reevaluate the usefulness of the combine’s physical tests and exercises as predictors of player performance. This study should encourage team personnel to consider the weighting and importance of various combine measures and the potential benefits of overhauling the combine process, with the goal of creating a more valid system for predicting player success.
Another study by Sierer, et. al. compared the NFL Combine performance differences between drafted and non-drafted players. Findings were slightly more positive. Although drafted athletes were found to perform better than non-drafted athletes, the success of each athlete in the NFL was not used as a criterion measure and predictive validity was not established. Boulier and Stekler used a data base from NFL drafts between 1974 and 2005 and a range of measures to determine the success of players selected in the draft. The study examined the success of drafting quarterbacks and wide receivers and also found combine test scores to be only slightly helpful in predicting NFL success at these positions.
It is understandable why it is so difficult to statistically determine success from field tests since football is skill specific and physical tests cannot mimic the many key situations for each player position. Clearly, there is room for improvement even in the area of speed tests where researchers found some predictive value. Football is a game of quickness, starting, stopping, and acceleration. An analysis of game play would reveal that it is a rare occasion when players in most positions sprint a distance of 40 yards. The First 3-step test and the 10-yard dash are much more sport specific for interior linemen (blocking, pass and run rushing) than the 40-yard dash. If the 40-yard dash is deemed necessary, the test should be changed to include split times at 5, 10, and 20 yards. Also, a plant, cut, and 10-yard acceleration test is also more football-appropriate for linebackers, defensive backs, and linemen.
Although the 2018 NFL Combine was more comprehensive and controlled than during the period the three studies above were conducted, it is time for further investigation to determine the predictive value of individual tests and combined scores on game performance in this modern era.
Boulier, Bryan Leslie and H.O. Stekler. 2010. Evaluating National Football League Draft Choices: The Passing Game. International Journal of Forecasting Vol. 26, Issue 3, July 589-605
Kuzmits, F.E., and A.J. Adams. 2008. The NFL Combine: Does it Predict Performance in the National Football League. J Strength Cond Res. Nov;22(6):1721-7.)
Sierer, S.P., Battaglini, C.L., Mihalik, J.P., Shields, E.W., and NT Tomasini. 2006. The National Football League Combine: performance differences between drafted and non-drafted players entering the 2004 and 2005 drafts. Journal of Strength & Conditioning Research: January 2008 – Volume 22 – Issue 1 – pp 6-12.