Some determination needs to be made about what the lifter considers to be a power snatch, as far as the height at which the weight is to be received, and to make sure that height becomes a fixed standard. Therefore, involuntary variations in depth are held to a minimum or eliminated completely.
Any lift received at just above parallel (thats your thighs parallel to the floor) or higher should count, as long as the depth is consistently achieved. The power snatch is only a variation for those who can do a full squat snatch. If the lifter is unable to do a full squat snatch, then the power snatch becomes their main event and not a variation. In fact, the opposite would occur where doing light weights in the full snatch would be a variation to their power snatch.
The power snatch should mainly be used as a warmup protocol for the lighter incremental increases and as the weight increases the lifter should gradually lower the receiving position until they are at an incremental weight where they have warmed up sufficiently to receive the weight in the full squat position.
For example, the above table shows a lifter with a snatch PR of 130kg, and how the snatch can be warmed up by gradually and voluntarily lowering the receiving position for each subsequent incremental increase. The clean & jerk could be warmed up the same way. For both lifts this would be done to gradually get the legs used to receiving the weight at the different heights by riding the weight down after reception. This is to eliminate any abrupt shock to the muscular system, and ensure a smooth transition from power to full.
Top lifters warmup by using the power snatch and ride down during those early incremental warmups, as Lasha Talakhadze is doing in the photo below, with 100kg. He receives the weight just below quarter squat and then rides it down into the full squat position. Once he feels he is sufficiently warmed up, then the power snatch is no longer needed.
Riding the weight down after reception when doing a power snatch is strictly for warmup purposes. A true power snatch, regardless of the depth reception, should be received without riding the weight down, but executed by immediately standing up from the point of reception.
A power snatch should be exactly the same technically, save for the height of the reception, as doing a full squat snatch.
It takes the same time in motion to do a power snatch as it does a full squat snatch, at least from the platform to locking-out the weight overhead. It takes 1 second regardless of how low or high the snatch is received. The power snatch will be an equivalency between the full snatch and power snatch, regardless of the receiving height. There will be a proportional drop off in the mass as the weight is pulled higher. The accelerated velocity and momentum are the same regardless of the various receiving heights. However, there will be faster overall times in motion (from the platform to standing up) from a full to a power snatch. This is what makes these lifts equivalent regardless of the height or the amount of weight being handled.
For example, a full squat snatch with 150kg in 2.2 seconds (from the platform to stand-up) and a power snatch at quarter squat (from the platform to stand-up) with 135kg in 1.5 seconds are equivalent in accelerated velocity and momentum. There is basically no difference between a power snatch and full squat snatch as far as the mechanics of the pull to full extension and the 3rd pull are concerned. The receiving height and overall time in motion are the only variables.
It would be difficult to correlate a power snatch to full squat snatch, due to the equivalencies, and there are too many different depth variations. Generally there should be about an 85% ratio of power snatch to snatch, if the power snatch is caught at about quarter squat. At lower depths the ratio increases to eventually become 100%. A muscle snatch without press-out might be around 60% of snatch. The variances of mass go from 60% to 100% depending solely on the height the weight is being received.
When doing doubles or triples in the power snatch the lifter should take great care in insuring each rep is voluntarily received at the same height. If each rep is subsequently and involuntarily lower, then the weight should be reduced in order to keep each receiving height consistent.
Catching each rep at different receiving depths voluntarily is different from the amount of weight causing each depth to be different, due to involuntary actions.
From a training standpoint, the power snatch cannot progress the full squat snatch because both lifts are technically the same as is the energy or power output. As stated before the main benefit of doing power snatches is in the early stages of warming up. There is also some benefit in teaching beginners the power snatch in order to show them how to power snatch into the full squat position. Aside from those two benefits, the power snatch’s functionality drops off considerably, unless the athlete is mobile enough so the motor pathways stay intact when switching from power to full. The power snatch should be considered a variation if it is trained off the platform. If it is trained as a partial lift it should be considered an auxiliary exercise, and trained at a reduced level of intensity and volume compared to the full movement. Even the variation should be trained at a reduced level of intensity and volume compared to the full movement.
By Jim Napier (www.strengthandvelocity.com).