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I am true believer that the actual running motion is the best way to running faster. Sure, strength and power exercises help OUTSIDE of the track, but you can only get faster by training to run faster at those speeds.
I wrote about Yoshihide Kiryu, Downhill Running, and Assisted Training Methods and James Smith wrote about Disseminating Effective Training Protocols for Sprinters.
As mentioned in the James’ article, there are several ways to add resistance to your running, but the most popular email and Facebook questions is always about the sleds. I don’t know why, maybe it’s because you have the most control over it, as compared to hill incline or head winds. And the Exergenie provides fantastic control over your resistance simply by turning the cylinder..
My quick answer has always been 10% of your bodyweight. If you weight 80kg, that’s 8kg, and you have to account for the weight of the sled. If you are low on cash, simply use a car or truck rubber tire, and use sandbags for additional weight.
Why 10%?
Because Charlie Francis said so.
But serious, he did say 10%, and we experimented with it. We found going too high, say 20%, the athletes were struggling to keep the same form and the ground contact was substantially increased. I don’t have any scientific proof of that, but you can just see and hear it. Remember, Coaching is an Art and a Science.
It’s like using a trampoline to practice basketball dunks. It may look pretty once you get “up there”, but you still have to “get there”. And the trampoline does NOTHING to help improve your vertical jump and forces required.
In this month’s Journal of Strength & Conditioning Research, (May 2014 – Volume 28 – Issue 5 – p 1241–1245) they studied the effects of Sled Towing on Sprint Starts.
The results are suggesting 20% weight on sleds instead of 10%.
I feel more research is needed, with better ways to measure other factors such as ground contact times and other parameters. And the end result MUST be faster times covering ground.
Below is the abstract. Discuss.
Sled towing is a popular method of sprint training. Researchers have struggled to identify a loading scheme that is most appropriate to improve sprint performance in the acceleration phase. The purpose of this study was to determine if loads of 10% body weight (BWT) or 20% BWT produced significantly greater propulsive ground reaction force (GRF) impulse, peak propulsive GRF, or a greater propulsive rate of force development (RFD) than an unweighted sprint start.
Seventeen healthy court and field athletes (10 men, 7 women; 20.9 ± 1.1 years) completed 5 starts of each condition (unweighted, 10% BWT, 20% BWT). Participants began each start in an upright staggered stance. Propulsive GRF impulse was greater in the 20% BWT condition than the unweighted condition in both limbs and greater in the 20% BWT condition than the 10% BWT condition in the front leg only, and vertical GRF impulse was greater in the 20% BWT than the unweighted condition.
In summary, our results suggest that a 10% BWT load is not sufficient to increase propulsive GRF impulse. A loading scheme of 20% BWT is sufficient to increase propulsive GRF impulse. Coaches seeking to improve sprint starts may observe improvements using a load of 20% BWT during training while towing a sled.
Jimson Lee
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