Introduction
I previously talked about some of the theory behind a good acceleration and why understanding the theory behind efficient acceleration mechanics is important. If you haven’t read that article, then I recommend you do so as it will make the ideas throughout this article much clearer.
In this article I am going to be talking much more concretely. Specifically, I’m going to be talking about which one exercise I believe is the best for improving your acceleration.
The best exercise for improving your acceleration is resisted sprinting. This exercise is great because it simultaneously develops both your acceleration technique and your power output abilities.
The Best Exercise for Improving Acceleration - Resisted Sprints
Resisted sprints are sprints where you intentionally make it more difficult to move forward by incorporating some form of resistance.
For example, you may attach a resistance band to a fence, tie it around your waist and then attempt to sprint while the band pulls you back (there are some especially long resistance bands made for this purpose).
An athlete using a weighted sled as a form of resistance
Another method is to attach a weighted sled to yourself, after which you will need to pull the sled along with you when you sprint.
No matter what method you choose (although later I will discuss which method I believe to be the best), all of these forms of resisted sprinting have one thing in common: they increase the horizontal force demands of the sprinter.
If you read the article I previously mentioned then this probably makes sense to you, otherwise it may sound rather abstract.
Basically, it means that the person will have to generate more force in the horizontal direction than they usually would if they were sprinting without any resistance.
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Why Is Resisted Sprinting So Good for Acceleration?
Acceleration is primarily about producing force in the horizontal direction. The more horizontal force you produce, the faster you will accelerate.
Also, we just learned that resisted sprinting increases the horizontal force demands of the sprinter.
Hence, the reason resisted sprints are excellent is that they provide us with a direct way to measurably load and train the quality that is most important for acceleration: horizontal force production.
The Magic of Resisted Sprints
The great thing about resisted sprints is that they literally force you to produce horizontal force. Let me explain.
When you sprint normally, you may be quite bad at directing force in the horizontal direction. Your shin angles may be very vertical, and you may not lean forward much. Consequently, your ability to accelerate is poor. No doubt you will still move forward, however it won’t be very fast.
However, now try accelerating while being attached to a sled with 30% of your body weight (30% BW) on the sled. In this case, your vertical shin angles and upright posture are not going to work. If you ever want to move forward, you must adopt the right acceleration mechanics.
Your body will not be able to physically move forward if you do not adopt the appropriate shin angles and forward lean. This is what I mean by resisted sprints forcing you to embrace favourable acceleration mechanics.
Resisted Sprints as A Teaching Tool
Let’s assume that you have very bad acceleration mechanics.
We could attempt to fix your technical mistakes by telling you to lean forward a bit more and to strike the ground backwards under your center of mass and so on and so forth. Of course, it is important to understand these basic acceleration principles.
However, a faster solution to help improve your technique would be to do some resisted sprints. As I mentioned earlier doing so will force you to adopt the right acceleration mechanics without having to consciously focus on all the various acceleration cues (‘stay low’, ‘strike backwards’ and so on).
Rather, your body will intuitively learn and hopefully ‘remember’ the desired technique after enough resisted sprint training.
An interesting way to see this principle in action is to do an unresisted acceleration, then do a resisted acceleration followed by another unresisted acceleration.
What you will often find is that the second unresisted acceleration will be a lot better than the first due to your body ‘remembering’ the more efficient mechanics from the resisted sprint.
That is why resisted sprints are so useful at developing your acceleration technique.
Power Development
Resisted sprints – while helping you to improve your technique – are also useful for helping you become more powerful.
This is particularly true for resisted sprints using a weighted sled. I mentioned earlier that there are various forms of resisted sprints. However, I believe the best method to be using a weighted sled (and god please not the parachute).
The main reason for this is simply because you can more precisely load a sled. In other words, you can know exactly how much weight is on the sled.
Compare this to a resistance band, where you are not entirely sure how much resistance is being applied.
Also, it is hard to precisely increase the amount of resistance with a resistance band, whereas with a sled you can add exact amounts of weight.
Coming back to power development using a weighted sled, you may have heard of the force-velocity curve before. Basically, the curve describes the simple fact that exercises that require a higher amount of force generally happen slower than exercises that require a lower amount of force.
For instance, a heavy back squat may take seconds to complete, whereas in an unweighted, unresisted plyometric jump, the total force may be applied in under 250 milliseconds.
Generally speaking, it is advisable for athletes to incorporate exercises along various points of the force-velocity curve into their training. Some slow, high force exercises (heavy squat, deadlift), some fast, lower force exercises (plyometrics, sprinting) as well as some in between (power cleans, med ball throws) .
But what does this have to do with sled-resisted sprints?
Well sled-resistance sprints can target various points along the force-velocity curve depending on how much weight you are using.
The more weight you put on the sled, the more force-oriented the exercise will be. Whereas the less weight you put on the sled, the more velocity-oriented the exercise will be.
This is excellent because you can adjust the weight of the sled (i.e. – the amount of resistance) depending on what you want to target.
For instance, if you wanted to target the very beginning of a sprint (the first couple steps), then you could use a heavier sled. Likewise, if you wanted to target, let’s say, the 5m-15m part of an acceleration then you could lower the weight.
How Much Resistance is Necessary?
I’ve sometimes seen people use a sled without any weight on it. This is rarely advisable as most of the time we desire much more resistance than the couple of kilograms that a sled might weigh. However, how much weight is a good amount?
A ‘very heavy sled’ (as it is sometimes called in the literature (1)) is around 70-80% BW. Indeed, if you try sprinting with this amount of weight on the sled it will most likely feel quite difficult to move. This amount of weight is only useful for improving the very start of an acceleration.
If you’re not very experienced and/or not very strong, then starting with an upper weight of ~50% BW is a good starting point.
Remember to always keep in mind that we want to keep these resisted sprints specific to sprinting. That means that we shouldn’t feel as though we are slowly dragging the sled through mud behind us – the movement should always be explosive.
But what about reps and sets?
Well, instead of staying at a fixed resistance/weight, I prefer to combine weighted-sled sprint training with the principle of contrast training.
Good introductory video on resisted sled sprints
Contrast Training
Contrast Training is type of training that involves performing a sequence of similar movement patterns that vary along the force-velocity curve.
In other words, performing two exercises back-to-back that involve similar movements but are at different speeds. For example, a heavy squat followed by a counter movement jump.
Contrast training has been shown to improve an athlete’s explosive abilities (2-4).
The principle is the same when it comes to weighted-sled sprint training. First perform a heavy resisted sprint, then lower the weight and perform another rep.
This can be continued by gradually removing more weight from the sled until your final rep for the set is done without any resistance.
This training method utilizes the concept of contrast training whilst also targeting various phases of your acceleration.
Famous sprint coach Randy Huntington has stated that he uses this method of resistance training with his athletes (including Su Bingtian, the Chinese sprinter who currently holds the fastest ever 60m split time of 6.29s – faster than Usain Bolt’s 60m split time of 6.31s that he ran when he achieved his WR time of 9.58s over 100m).
“A heavy sled to me is a sled with close to your bodyweight, then we went half the bodyweight, then we would quarter the bodyweight”– Randy Huntington on the Just Fly Sports Performance Podcast
Su Bingtian’s explosive acceleration
The fact that, Su, one of the fastest accelerators ever uses this method to train his acceleration says something about how effective it is.
Also note that Randy considers a heavy sled to be almost 100% BW. Remember that he is typically coaching world-class athletes. As I mentioned before don’t be afraid to use less weight for your heavy sleds if you’re just starting out.
A Training Program
So, we want to use a weighted sled for performing our resisted sprints, and we want to vary the weight as to utilize the principle of contrast training.
I made an Instagram post describing a possible workout (sets and reps)
However, ultimately there is no hard rule about the exact number of reps and sets necessary. The most important factor is how you feel. Quality of reps is paramount when it comes to sprint training.
If you feel exhausted and that you will not be able to give 95%+ on the next rep, then you should either stop, or rest more before the next rep. Since quality is most important, don’t be afraid to rest for long periods of time between reps and sets if you feel that you need to.
Play around with the reps, sets and weights that work for you and get accustomed to knowing when your body is not prepared to complete another high-quality rep.
Other than that, if you start with a relatively heavy weight, and then reduce the weight as you complete more reps, then the training session you decide should get the job done.
It’s always very fun to do an unresisted sprint after sprinting with the weighted sled since you feel much faster (and in reality you probably are!).
Conclusion
A small investment is usually required to get started with resisted sled sprinting (as most people don’t usually have a sled and weights lying around). However, it is by far the best exercise for improving your acceleration.
Combining sled resisted sprinting with the concept of contrast training can quickly make a huge impact on your explosiveness and acceleration. So, before you plan on incorporating a whole repertoire of gym exercises into your routine, make sure you’re getting some resisted sprinting in first.
References
1) Morin, Jean-Benoît, et al. “Very-heavy sled training for improving horizontal-force output in soccer players.” International journal of sports physiology and performance 12.6 (2017): 840-844.
2) Thapa, Rohit K., et al. “Effects of complex training on sprint, jump, and change of direction ability of soccer players: a systematic review and meta-analysis.” Frontiers in Psychology 11 (2021): 627869.
3) Lagrange, Sébastien, et al. “Contrast training generates post-activation potentiation and improves repeated sprint ability in elite ice hockey players.” International journal of exercise science 13.6 (2020): 183.
4) Pagaduan, Jeffrey, Brad J. Schoenfeld, and Haris Pojskic. “Systematic review and meta-analysis on the effect of contrast training on vertical jump performance.” Strength & Conditioning Journal 41.3 (2019): 63-78.
