Do sleds pull their weight - or just drag you down?
Written by Sean Maloney
Sleds are big – and we're not just talking dimensions! Everyone from elite rugby players to contestants on TV's The Biggest Loser can be seen pushing and pulling them, but how well do they work?
We were curious about what makes sleds a favoured choice for so many – so in true Family Fortunes style, we asked 100 people why they would use sleds in their training. The two most popular responses are examined on the next page.
So are sleds for you?
We need to keep in mind that sled training is by no means the only way to train acceleration. While its little nuances make it a valuable supplement to a typical strength and conditioning programme, it is just that: a supplement.
Sled training appears to be an effective way of improving acceleration, a key performance determinant in the majority of sports. In addition, it offers certain advantages over other modalities when it comes to conditioning work. However, sleds are costly and are by no means an essential purchase. Any opportunity to try this approach before investing should definitely be taken up – but deciding whether sleds are worthwhile training additions is entirely up to you, and your budget!
Why would you use sleds in training?
The most common answer was: 'Improvement in speed and acceleration'.
How sleds contribute:
i) If speed is your main aim, the sled is unlikely to help you achieve it.
In the July issue of Performance, we featured a metaanalysis by Con Hyrsomallis from the University of Victoria, Australia that sought to evaluate the effectiveness of sled training . It was determined that such training can improve sprint performance, although no more than regular sprint training.
ii) For those seeking training acceleration, sled training may well be beneficial.
The Hyrsomallis paper did, however, highlight the potential for sled training to improve acceleration, and West et al. recently tested this concept in professional rugby players . The researchers set up two training groups: a sled sprint group and a normal sprint group. Both performed three sets of 3 x 20m sprints, but the sled training group performed their first set towing along a sled loaded with 13% of their bodyweight. Whilst both groups improved their 10m and 30m times over the 6-week training period, the sled training group showed greater improvements above 10m (2.4% in comparison to 1.1%).
The primary goal of resisted sprinting is to increase the amount of force an athlete can produce in each stride. Whilst available research demonstrates that sleds are an effective way to do this, the exact mechanisms are unclear. However, benefits over other forms of training are definitively associated with certain aspects of sled training, in that it:
Figure 1. An acceleration body position: note that the athlete is at a 45° angle to the floor and that the hip extends behind the body (hip hyperextension).
Why would you use sleds in training?
A close second in our poll was 'Improvement in conditioning'.
Sleds contribute in two main ways:
i) Minimise eccentric contraction to avoid compromising recovery.
Eccentric muscle action generates high levels of tension within the muscle and has the potential to induce significant fatigue and muscle damage. Whilst this plays an important role in overall training gains, you can have too much of a good thing. Sled training can be used to train concentric muscle actions whilst minimising the eccentric – so called 'eccentric-less training'. If used sensibly, this allows you to reap the benefits of training more often without compromising recovery .
Example: during a sled drag, the hip, knee and ankle extend to move the sled forward – concentric muscle action. As soon as the extension phase is completed, the leg is then unloaded – minimal eccentric muscle action.
ii) Including the fun factor helps us persevere.
Anything that can make this type of training more enjoyable is a good thing! We do not usually see the words 'fun' and 'conditioning' together, but enjoyment is a crucial and often overlooked factor in training. It is much easier to stick to your training and give your all during sessions if that fun factor is there. Sleds are a novel tool, something slightly out of the ordinary. They lend themselves well to use in group training and encourage an enthusiastic atmosphere around them. Embrace enjoyment and see the results!
Broadly speaking, we can split the process down into metabolic conditioning (training specific energy systems) or muscle conditioning (training specific muscle groups) – and sleds may well fit the bill for both. Once more, sled training is not the only option to improve conditioning, but it can certainly make a valuable contribution.
1. Hrysomallis C. The effectiveness of resisted movement training on sprinting and jumping performance. J Strength Cond Res, 2012, 26, 299-306.
2. West DJ, Cunningham DJ, Bracken RM et al. Effects of resisted sprint training on acceleration in professional rugby union players. J Strength Cond Res, 11 June 2012 [epub ahead of print, doi: 10.1519/JSC.0b013e3182606cff] (accessed September 2012).
3. Jenkins ND, Palmer T. Implement training for concentric-based muscle actions. Strength Cond J, 2012, 34, 1–7.
Sean Maloney is a strength and conditioning coach, lecturer and writer. He works with both the London Sport Institute and Middlesex University, UK, and runs strength and conditioning company, Maloney Performance.