Tomorrow will begin a new 3 week training block for baseball.  We are starting into Week 7 of the Fall Off-Season.  During the next two 3 week blocks we will begin implementation of our resisted speed program. 

The effects of resisted sled-pulling sprint training on acceleration and maximum speed performance

Effects of Resisted Sled Towing on Sprint Kinematics

I’m a big fan of resisted speed work.  First understand I’m not talking about loading up a sled with 200 lbs. and towing it at the speed of a garden slug. 

Whenever we utilize resisted sprint training we want to make sure the dynamics of the movement do not change.  We want to maintain the exact same technique throughout our runs rather towing an object or not.  Once technique is compromised the carry over to regular sprinting becomes less and less.  Not only that but doing enough of poor quality towing and you will train an athlete to become slower.  The body adapts to how it is trained always.  When towing too heavy of an object ground contact times become longer, center of mass lowers, torso angle increases, etc.   These deviations in technique can wreak havoc on a speedy athlete. 

For more information on truly being movement specific look at one of my previous posts or check into anything by Yuri Verkhoshansky and the Eastern Bloc. 

Sport Specific

Charlie Francis always recommended a 10% rule.  I should amend that actually.  He began implementing a 20% rule early in his career but revised it to 10% later on.  This meant never deviate an athletes performance by more than 10% in a loaded or unloaded exercise.  This was measured by time in speed training.  If an athlete ran a 4.50 40 yard dash, then when loaded the athlete should still be able to run under 4.95 sec.   If the athlete cannot achieve this then the load is too great causing too much deviation in speed mechanics. 

When I see athletes towing tires and dozens of 45# plates for “speed” work it makes me cringe.  Sure there are places in the training when towing heavy objects may be warranted but I don’t think it’s in a speed program.  We want our guys to run fast all the time so our resistance will always remain light.  Obviously the surface that athletes are running on plays a huge part.  The coefficient of friction will go into how heavy an object athletes should be working with.  Towing on grass vs. artificial turf vs. cement will all result in different loads.  It’s always better to err on the side of too light than the side of too heavy.


  1. Zach,
    Lots of good points. Lots of heavy sled push and pulls are done poorly. I agree its key to keep the athlete training with “speed”, but what does that mean and why is 10% too much.

    For example in that heavy sled pull photo above with me sitting on the sled, with Mark maintaining short contact times, he is not moving very far on each step. I believe in this case (everything has some context specificty) maintaing a short contact time is the priority, not how much time it takes to cover ground.

    Check out this article and let me know what you think

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