As a strength and conditioning professional one of the most prevalent questions we are asked is “Can I get my 40 yard faster and how fast can I be? This question is easy to answer, for starters everyone can get faster because speed can be taught and how fast can an athlete become really depends on their genetic makeup. According to Brent McFarlane (1987) sprinting speed can be learnt through motor educability, he goes on to explain that the skills and techniques of sprinting must be rehearsed and perfected at slow speeds and then transferred to sprints at maximal velocity. Most of us know the definition of speed is stride frequency x stride length; McFarlane also defines it as sprints at 95 to 100 percent up to 60 meters or 6 seconds of sprinting at maximum speed. Luis Cunha (2005) explains a sprint is determined by the ability to accelerate, the magnitude of maximal velocity and the ability to maintain velocity against the onset of fatigue. Luis explains the different phases of a sprint into the start, acceleration, transition, maximal running, and deceleration. For this paper I will go over the 40 yard dash because this is the most common question in my field. The forty yard dash is a test used in many sports to test speed more importantly acceleration and is approximately 36.576 meters. Brent McFarlane’s (1997) article A Basic and Advanced Technical Model for Speed he states that Loren Seagrave and Kevin O’Donnell divide the acceleration phase into 30 meters which 0 – 12 meters is pure acceleration and 12-25 meters is transition. They go on to explain from 25 meters to 60 meters as the maximum velocity phase of the sprint. So, for the first 27.34 yards of the 40 yard dash an athlete is in the acceleration phase and rest of the 12.66 yards the athlete is in the maximal velocity phase.
The start of a 40 yard dash is first based on the athlete’s explosive power to help get them from a static position out into the drive phase of the sprint. Many coaches today have their athletes start in a 3 point stance athlete stands with front foot 2-6 inches from line depending on the athletes size and back foot 2-4 inches from front foot with toes facing forward. The athletes front knee should be bent nearly at 90 degrees and back leg around 120 degrees with hips slightly above knees, back flat and chin tucked. The left arm is bent at 90 degrees at the hip if the left leg is in front, and the right arm is on the line with thumb pointing towards your left foot and index finger point to the right. The athlete’s right shoulder is directly over the right hand with the athlete’s weight leaning forward.
Once the athlete has left the static position the athlete is now in the acceleration or drive phase. Michael Gough (2006), defines the acceleration phase from the initial movement of ground contact until the athlete reaches top end speed. A powerful triple extension of the hip, knee, and ankle joints is important for maximum power development off the start. Forward body lean is critical during the acceleration phase with the shoulders always over the hips. Most coaches want the athlete driving out in a 35 to 45 degree angle with elbows at 90 degrees and driving their heel over their knee with foot dorsiflexed and foot striking under hips. In fact, research by Weyand, Sternlight, Bellizzi and Wright (2000) indicated that the force applied at ground contact is the most important determinant of running speed. Ken Jakalski (2008) states in his article that the dorsiflexion of the ankle is the “magic bullet” of the sprint cycle. He explains this of the dorsiflexed ankle because it puts a stretch on the gastrocnemius, soleus and achilles complex which contributes to knee flexion and hip flexion. He goes on to explain that if the athletes does not dorsiflex the ankle, the gastrocnemius soleus and achilles complex cannot help out as a leg flexor. If the gastrocnemius cannot assist in this process, another muscle group will, which are the hamstrings. Hamstrings should not serve a primary role as knee flexors they are hip extenders, not knee flexors. If the hamstrings are called upon to assist in knee flexion, they will be less effective in carrying out their primary responsibility.
The next phase of the forty yard dash is maximal velocity. This takes place for the last 12.66 yards. Michael Young (2007) of the USA Military Academy and Human Performace Consulting explains there are three primary goals of maximal velocity sprinting: preservation of stability, minimizing braking forces and maximization of vertical propulsive forces. Preservation of stability is the body’s ability to stay in perfect posture for the sprint because when stability is disrupted the loss of elasticity occurs. This stability relates to the athletes core for the most part, think of a squat an athlete holds their breath on the way down to support their back and keep their spine protected. The next goal is to minimize braking forcing which is any force that act in the opposite direction of the desired movement. The primary cause of excessive braking forces is making ground contact too far out in front of the athlete’s center of mass. This can go back to the stability goal because if an athlete has good stability the athlete is less likely to lean back or stand strait up which tends to disrupt the foot strike under the hips. The last goal is maximization of vertical propulsive forces which is the distance traveled in the air before ground contact. Vertical propulsive forces help the athlete with a more effective ground contact position and an increase in negative foot speed which when the foot is moving backwards at ground contact with respect with body moving forward; which, in turn helps the athlete accelerate through the line. Another benefit to the maximization of vertical propulsive is an increase in leg stiffness which is the ability of the legs to act like a spring during contact. Actually, Bret, Dufour, Messonnier and Lacour did study on leg strength and stiffness as ability factors in 100 meter sprints and found that leg stiffness is critically important to maximal velocity sprinting and the maintenance of momentum developed during the acceleration period of a sprint.
Throughout this paper one can see that there are many detailed mechanics through a 40 yard sprint. In a recap we know how to start, we know during the drive phase the athletes elbows are firing past the hips to the shoulders at 90 degrees, the heels are driving up over the knee, the shoulders are in advance of the hips and the athlete is making ground contact beneath the athletes hips which helps drive the athlete forward. During max velocity phase the athlete is doing everything that is in the drive phase except now we are trying to aim for more of a vertical propulsive movement. There is many other factors that go into sprinting for instance breathing, power and strength but for the purpose of this paper I am just explaining the mechanics of a sprint.
Now, that sprint mechanics are understood, what are some improper mechanics that athletes usually do and how can they be fixed. For starters many young athletes have problems with mechanics and it starts with their posture. Most young athletes have tight hips, glutes, hamstrings and gastrocnemius, soleus and achilles complex, internally rotated shoulders and an everted foot due to sitting in class all day. Think about if these kids are in flexion all day and that is what their body knows. So, how can these athletes improve their posture and the answer is through corrective exercises. Pete Egoscue suggests in his book Pain Free to do arm circles for internally rotated shoulders, and many other great corrective exercises for the hips, glutes, hamstrings and gastrocnemius, soleus and achilles complex. But, the most important corrective exercise when it comes to sprinting is foot circles. If an athlete has a foot that is everting and supinating the athlete may lose up to 2/3 or more of surface area and all important assistance of the knee and hip and their associated musculature (48). Once foot circle are performed the athlete feels an increase on surface area as well as more strength because of the assistance of the knee and hip so, if an athlete increases surface area, the athlete then increases force and if the athlete increase force the athlete in turn increase speed with proper sprint mechanics. The next error most athletes are with their elbows many athletes kick their arm back to 180 degrees past their hip which turns their arm into a long slow pendulum. Some athletes cross their bodies with their arms and many do not lock their wrist out which can inhibit the stretch reflex mechanism in the athletes shoulder if the hand supinates past the hip. These improper elbow mechanics can be improved by seated arm swings drills and arm circles. Brown and Ferrigno (2005) explain seated arm drills Starting Position: Seated on the floor with the legs straight out in front of you. Swing arms in a sprinting motion. Elbows should be kept at 90 degrees and keep hands relaxed. Your hands should come up to about shoulder height and should go past your hips in the back. Be careful to not bounce off of the floor as you swing your arms faster. Other problems athletes have is driving heel over knee, driving off of their power pads, heel contacting ground and shoulders not over hips. To help improve these faults there are the Mach Drills invented by Gerard Mach. A cornerstone of his system was the A B & C drill series. Mach (1977) broke the stride into its components parts, knee lift, foreleg action and the push off through the drills. The A Drills were designed to work the knee lift component. The B Drills were designed to work on foreleg reach or pawing action. According to Mach All exercises with leg extension and active down are special exercises to strengthen the hamstrings (6). Mach (1977) also explained The marching and skipping exercises were designed to develop the technique required for body lean, arm action, high knee lift, leg extension, and keeping the center of gravity high, but did not emphasize the strong driving forward or push forward action and the C Drills were designed to work on push off and extension (6). Brent McFarlane uses similar drill for improving speed and technique as does Tom Shaw. Other ways to enhance performance is by doing explosive Olympic lifting and plyometrics. In fact, Eduardo S¡ez, Gonz¡lez-Badillo, Juan Jose, Izquierdo did a study on Low and Moderate Plyometric Training and found that the lower training frequency produced a greater jumping and sprinting gain compared to high frequency. Therefore, sometimes as a coach remember less is more.
In closing, one can see how complex and how much detail goes into sprint work. Again, there is much more that goes into sprinting besides mechanics for instance strength, muscle fibers, breathing and etc. Finally, remember that the start and the finish of a sprint are equally important and if you want to run a good 40 yard dash there is much more than just genetics that come into play. In the words Vern Gambetta used in his article about speed drills there are many roads to Rome and another famous idiom there are many ways to skin a cat. What this mean is coach the drills and training that work for your athletes.

References

1. Bret, C., Rahmani, A., Dufour, A.B., Messonnier, L., and Lacour, J.R. (2002). Leg strength and stiffness as ability factors in 100m sprint running. Journal of Sports Medicine and Physical Fitness. 42(3): 274:281.
2. Brown, Lee and Ferrigno, V. (2005). Training for Speed agility and Quickness: Champaign, IL: Human Kinetics.
3. Eduardo S¡ez, Gonz¡lez-Badillo, Juan Jose, Izquierdo, Mike .Low and Moderate Plyometric Training Frequency Produces Greater Jumping and Sprinting Gains Compared with High Frequency. Journal of Strength and Conditioning Research. 22(3): 715-725. 2008.
4. Gough, Michael. The Forty-Yard Dash for the High School Athlete. National Strength and Conditioning Association Journal. 28( 2): 24-25. 2006.
5. Jakalski, Ken. Sprint Technique and Speed Training. 2008. Enhanced Fitness and Performance.http://www.enhancedfp.com/sport-specific/track-and-field/400-meter-training-ken-jakalski
6. Mach, Gerard. Sprinting & Hurdling School. CTFA 1977: Page 6
7. McFarlane, Brent. A Basic and Advanced Technical Model for Speed. National Strength and Conditioning Association Journal. 15(5): 57- 61. 1993.
8. McFarlane, Brent. A Look Inside the Biomechanics and Dynamics of Speed. National Strength and Conditioning Association Journal. 9(5): 35-41. 1987.
9. Pete Egoscue (Author), Roger Gittines (Contributor) (1998). Pain Free: A Revolutionary Method for Stopping Chronic Pain: New York: Bantom.
10. Weyand, P., Sternlight, D., Bellizzi, M. and Wright, S. (2000). Faster top running speeds are achieved with greater ground forces not more rapid leg movements. Journal of Applied Physiology, 89, 1991-2000.
11. Young, Michael. Maximal Velocity Sprint Mechanics. Track Coach. No. 179. Spring 2007.