Firstly, the article is not intended to be superior to other models because I haven’t yet found a model that attempts to convey how much resistance to train against when training for sprinting. Whilst various researchers show the force produced during the start, first step, second step, 14-16m mark and top speed of approx 9.5 m/s I felt the need to know how much force is produced during the entire acceleration. In this way, training methods could be modified or developed in order to be more velocity or movement specific. For example, when nearing maximum speed only between 10 and 15 kg of horizontal force needs to be produced although it must be realised at great angular velocity. Therefore, when doing an exercise such as cable-kickbacks one only needs to lift this amount and move the leg at a practical speed. Strength training with this specificity would allow an adaptation in the prime moving muscles that could be progressed over time.
This model is described as Newtonian simply because we use Newton’s equations of motion. It is intended to be simple enough to be able to supplement a coaches plan. The classical work of researchers such as Blickhan, Farley, McMahon (spring mass) or research work on energy systems are difficult to relate to training methods for most coaches. The tools readily available to coaches are resistance training, plyometrics, ballistic jump squats, Olympic lifts, hill running etc. for which I’m hopeful the Newtonian model can provide some guidelines (on horizontal force). The work of the respected aforementioned researchers on the contribution of elastic recoil of muscle-tendon complexes is appreciated in the calculation of forces produced per stride as the forces are as a result of such mechanisms. Instead of focusing on internal mechanisms that are rather complex, the sprinter just needs to know that they should produce a horizontal force of the order of 79 kg from a split stance that would replicate the stance in a starting block, in 300 milliseconds. If they can’t then why not? A coaching strategy could be to focus on speed of movement if the sprinter can lift this load already, and a reasonable guide is to be able to take a first step length of 1.23 metres as a result. From there the step length should increase gradually as this could make efficient use of fuel sources within the muscle. The Newtonian model is a guide, a point of reference to help coaches who I’m sure would not take the information as the gold standard and take into account the various individual differences in their sprinters.
Apologies for the long explanation here. I tried to keep the Newtonian model article as short as possible as well.
No need for apologies (i actually had to remove my quote to fit mine in here)
Your model still seems to lack or understate the elastic contribution to force, impulse, and power in acceleration. The percentage of elastic/eccentric/ssc force contribution to acceleration gets larger as time in acceleration grows larger while the percentage of concentric force contribution grows smaller as time in acceleration grows larger. There are two distinct phases of acceleration, three if you consider block clearance, a fast component which is the part of acceleration which is the first part of the velocity curve where the greatest amount of acceleration occurs, then the second part is the slow component which is the transition phase. The biggest difference between the two is stride rate drops and stride length increases, but speed still increases. In essence the legs work as adjustable springs and pistons in tandem during acceleration the former adjusting leg stiffness to compensate for the latter’s inability to produce force from concentric sources because of decreased contact times. The elastic recoil contribution to sprinting cannot be understated and it seems the Newtonian model you present doesn’t account for this.
To take this further into the application realm. I think trying to apply such a model would lead to what already occurs in European training, and to some extent Australia, and in many American HS’s and some colleges and universities. I see little cross-over possibilities with an unsupported movement such as cable kickbacks in enhancing sprint capabilities you get away from the specific needs involved in sprinting and sprint acceleration especially the latter portions of acceleration.
I feel the weightroom provides both general and specific benefits to sprinting in both max velocity and acceleration, but they are a bit different. Max. Strength increases force output potential and power work increases power output potential, both help in the creation of rate of force development, but there is little elastic benefit and any elastic benefit that can be attained in the weightroom would be considered by most as dangerous such as ballastic lifts which are not through full ranges of motion, but something I believe in.
Plyometrics seem to focus on reaction/contact times, but reaction/contact times are very activity specific. Plyometric training should be done to achieve greater stiffness and this seems to be landing specific which need to draw into and account for elastic feedback loops and how they affect the elastic structures.
For proper and enhanced applications of force to be attained the coach must be informed of the motor learning along with motor control and biomechanical aspects of sprinting first before trying to develop those qualities. The end product of many sprint training applications tend to produce either an athlete who can produce force extremely well, but has underdeveloped elastic capabilities who cannot maximize such force production at the latter stages of acceleration or it produces the athlete who has well developed elastic capabilities, but lack the force producing capabilities to maximize their elastic capabilities in acceleration.