The Olympic lifts and their variations are used extensively in the strength and conditioning of athletes. They are performed quickly (barbell velocity of 2-4 meters per second) and generate great power (depending upon the author they may require the athlete to generate between 20 and 50 watts/kilogram during the second pull). The challenge is that the lifts are extremely technical. With that in mind, some strength and conditioning coaches use a partial movement, called a pull, in place of cleans and snatches. The pull involves performing the explosive part of the lift without moving under the bar, so in theory the athlete gets the benefits of the lift without having to perform the most difficult technical parts.
Comfort et al in the May issue of the Journal of Strength and Conditioning Research investigate the clean pull with the bar beginning at mid-thigh to determine how the load on the bar impacts kinematics and kinetics. This is important information as it can provide guidance into selecting the most effective resistance for an athlete with limited training time.
In this study, the subjects were collegiate team sport athletes. Prior to the study, the subjects maxed out on their power clean. During the study, they were randomly asked to perform one set of three reps at 40, 60, 80, 100, 120, and 140% of their power clean 1-RM. These lifts were analyzed in terms of velocity, displacement, peak power, impulse, and rate of force development. Some of the results are what you’d expect:
- The displacement of the bar (i.e. how much it moves) decreases as the weights get heavier.
- The velocity of the bar decreases from about 1.6 meters/second to 1 meter/second as the weights move from 40% of 1-RM to 140% of 1-RM.
Having said that, some of the results are not what you’d expect:
- Peak force increases as the weight on the bar increases, but not much. From 2500 newtons at 40% of 1-RM to ~2750 newtons at 140% of 1-RM.
- The rate of force development does not follow a linear trend as the weights increase and is greatest at 120%, closely followed by 140% of 1-RM.
- Peak power is greatest at 40% and 60% of 1-RM. It is lowest at 140% of 1-RM.
The authors note that in their studies (and others), peak power in the power clean occurs somewhere around 70-80% of 1-RM. They suggest that this difference is due to the extra phases in the power clean than in the lift studied here.
Now, the results are interesting from the standpoint that they reinforce the need to identify why one is training and organize the training accordingly. For example, if the clean pull is being used to train power then the lower loads would be important. In the training of Olympic lifters, pulls are used as a strength exercise. In other words, they are done to make the lifter stronger during the second pull (lifters pull the bar to a greater height when performing pulls than when they perform the full lift, so this exercise strengthens that part of the lift). So for that purpose, looking at the study results, it would be appropriate to any of the weights studied, with the greatest occurring at the heaviest weight (in other words, this is going to be limited by the athlete’s ability to maintain technique with the weights). If the desire is to train rate of force development, then the heavier weights are going to be important.
Comfort, P., Udall, R., and Jones, P.A. (2012). The effect of loading on kinematic and kinetic variables during the midthigh clean pull. Journal of Strength and Conditioning Research, 26(5), 1208-1214.