A Push in the Right Direction: Prowlers and Sled Training
The origins of sled work can be traced to the Scandinavian forestry industry, at a time when loggers had to drag trees from areas of the forest not accessible by trucks. It’s believed that such training enabled athletes from this country to excel in the deadlift, and as such heavy sled dragging was adopted as a training method by many powerlifters. But this type of training has much, much more to offer.
In recent years, resistance running methods have become popular in workouts designed to reduce bodyfat. Studies have shown that sled sprints of 20-30 meters performed in intervals produce favorable metabolic responses that stimulate fat burning. Research also suggests that interval training is particularly effective for reducing subcutaneous fat, which is the layer of fat just below the skin.
Sled training is low-impact, which is a plus for those with orthopedic issues that make running difficult. And because there is minimal eccentric overload in sled training, trainees can perform intense bouts of such training without experiencing the soreness associated with conventional forms of training.
Beyond these advantages, sled training can be especially valuable for making athletes faster.
Although pulling sleds is popular, especially among football players, one drawback is that the rope attached to the sled takes up a considerable amount of space. If you have 15 meters of space to pull a sled, a quarter of that could be used up in the length of the rope. A more practical idea is a push sled, commonly referred to as the prowler.
Sled pushing became especially with athletes who do a considerable amount of training indoors. Other types of resistance running have been tried, such as wearing ankle weights and running uphill, but these methods can adversely affect the biomechanics of running. Running with parachutes were popular in the 90s, but the resistance is delayed because you have to take several steps before the parachute opens – also, the resistance in minimal.
Being able to accelerate quickly from the start is key to athletic success in many sports. A sled provides immediate resistance and can provide not only a high level of resistance but also a precise level of resistance. It also can be used to help with running technique because your arms are stationary you can focus more on leg drive.
To get the most out of this type of training, a few guidelines must be followed. If your goal is to improve sprinting performance, you should only push a sled for short distances, about 22 meters (25 yards). Once your body goes into an upright position through the transition phase of a sprint, acceleration decreases – working on the drive phase for a longer distance is not a natural movement that can cause a breakdown in body mechanics. An analogy is performing high-rep snatches.
The amount of resistance you use is critical, and has become quite a point of controversy is the sports science literature. Many coaches believe that if an athlete’s speed reduces by more than 10 percent, the resistance is too heavy. For example, one study found that when a weight was used equal to 32 percent of bodyweight, running velocity decreased by 23 percent and ground contract time – a critical component in sprint – increased by 20 percent. In contrast, one eight-week study on male amateur soccer players found that weights up to 80 percent of bodyweight produced significant improvement in sprinting ability.
Regardless of the protocol used, your initial workouts should be with an empty sled to get accustomed to the movement. Resistance can be added as long as technique is maintained. This is where a coach’s eye comes in handy – they should be focusing on technique, not just acting as a cheerleader.
Most push sleds have long vertical handles, often with 1-2 crossbars, that enable you to grasp them high or low. The lower position will enable you to develop greater acceleration from a low position, whereas the high vertical handles will work the transition phase between the start of a sprint and the upright sprint position. Because the quads are more active in the lower position, sled training can be used early in a program designed to recover from a hamstring injury.
One challenging workout protocol used in energy-system training is to perform several sprints in the lower position, then as fatigue sets in perform several sprints in the higher position. From here, you could finish off with some regular sprints. But if your main goal is speed, consider contrast training.
Contrast training is based on the theory of post-tetanic potentiation, which states that a more powerful muscular response can be performed if it is preceded by a strong muscular contraction. We often see baseball players swinging a weighed bat immediately before going up to the plate; when they switch to a regular bat, they feel the contrast in weight will enable them to hit the ball harder. What is happening is that the heavy bat activates the more powerful fast-twitch fibers. When the athlete switches to a regular bat, the nervous system is conditioned to anticipate that it still needs to activate those fibers with the lighter bat.
Weightlifters often use contrasts methods in their workout to produce greater speed and power, such as by performing a few reps of squats before moving on to the quicker lifts such as the snatch. Or they will work up to a heavy single in a lift such as the snatch, reduce the weight by about 20 percent, and then work back up to often complete an even heavier lift. Credit for this method should be given to Canadian strongman Doug Ivan Hepburn, the first man to bench press 500 pounds, as he would often start his workouts with heavy singles followed by the same movement with slightly lower weights for higher reps.
One way to use contrast training with sled is to push a sled (holding the handles in the high position) for about 5 meters, release the handles, step to the side of the sled, and then take off in an all-out sprint for about 10-15 meters. You will find that when you release the handles, you will experience a sudden burst of speed as if someone was pushing you from behind.
Whether your goal is lose a few pounds or to train for athletic superiority, sled training is a versatile tool that will improve the effectiveness of your workout.