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Effect of post-activation potentiation on swimming start

by P. Debraux | 22 March 2018

swimming, start, postactivation potentiation, squat, warm-up, free-style, sprint, strength, conditioning, science, sport, training, performance
Starting position in swimming on older models of starting blocks

Figure 1. Starting position in swimming on older models of starting blocks.

In swimming, in sprint events such as the 50m freestyle, the starting phase (i.e., the time measured over the first 15 meters) contribute more than 30% of the total performancal power produced by the lower limbs. This may suggest that an increase in power in lower limbs would allow a gain on the starting phase.

There are many protocols for improving power output. Among them, a widely used method is called contrast : the aim is to work against a heavy resistance (i.e., > 80% of the 1RM) and then to work with a light resistance (e.g., body weight).

The physiological principle underlying this technique is called post-activation potentiation by (PAP). To best explain this principle a number of prerequisites are necessary and we will soon devote a complete review on this subject. However, to put it simply, the light load performance is significantly improved after a PAP stimulus, on the same muscle groups. For example, a series of squats performed at more than 80% of the 1RM will improve the performance during a vertical jump that will be performed in the minutes that follow. Nevertheless, this phenomenon is dependent on many parameters, and in particular, the recovery time between the PAP stimulus and the light load movement...

The Study

In 2011, a team of English researchers from Swansea University wanted to determine in international swimmers (Sprint specialty) what was the optimal recovery time for maximum benefits after a PAP stimulus and what were the effects of a PAP stimulus on the first 15 meters in comparison to their traditional warm-up.

For this, 9 international swimmers (7 men and 2 women) participated in this study. The experimental protocol was conducted over 3 sessions, each spaced at least 48 hours apart :

Session 1 :

Figure 2. 1/2 Squat.

At first, the swimmers realized a CMJ jump alone. Then they performed 1 series of 3 repetitions at 87% of their 1RM squat before performing CMJ after 15s, 4, 8, 12 and 16 minutes (Fig. 2). This session allowed to individually determine the optimal recovery time to observe an improvement.

To compare performance, the jumps were performed on a force plate, which allowed to determine the maximal power output and the jump height. In that way, it was possible to compare these parameters during the jump made before the PAP stimulus and the jumps made after.

Session 2 and 3

The swimmers made a start and the first 15 meters in the conditions of a 50m freestyle sprint. This race start was preceded either by their specific traditional warm-up or by a series of 3 repetitions at 87% of their 1RM squat. The optimal recovery time between the PAP stimulus and the start determined during Session 1 was used.

To compare the starts, a video analysis was used to measure the time at 15m. And a force plate was placed on the starting block to record the vertical and horizontal forces.

Results & Analyzes

Regarding the optimal recovery time after a PAP stimulus, the results of this study showed that for all swimmers in this group, the time to improve performance at a CMJ was 8 minutes after 1 set of 3 reps to 87 % of 1RM in squat. After 8 minutes, the maximal power and the jump height were significantly greater than the jump made before the PAP stimulus.

Concerning the race start, the researchers did not observe any significant difference between the time on 15m after a specific traditional warm-up and the time on 15m after 1 series of 3 repetitions at 87% of the 1RM squat. Concerning the vertical and horizontal forces applied to the starting block, there was a significant gain after the PAP stimulus, but this did not result in a better time.

Figure 3. New FINA approved swimming starting block. Source image www.omegawatches.com

This study shows how it is possible to individually determine the optimal recovery time after a PAP stimulus. Although there is no difference in time over 15m, it is interesting to note that a series of squats more than 80% of the 1RM as a warm-up allows the same benefits as a traditional warm-up, which volume is significantly larger. Even if the horizontal forces are higher thanks to the stimulus PAP, the inclination of 10° of the starting block couldn't allow a good application of the forces at the level of the feet. At the time this study was conducted, the new starting blocks had not yet been put in place by FINA. These new blocks have the particularity to look much more like the starting blocks used in athletics (Fig. 3). Such blocks allow better application of horizontal forces. It would be interesting to observe their role after a PAP stimulus.

These results open some perspectives, although it may be difficult to set up such a protocol before a competition. However, more research should be done on warming up. The authors of this article propose a work on a warm-up combining both a specific aquatic work and a muscular work in force.

Practical Applications

Post-activation Potentiation (PAP) still requires more informations to understand how it works and especially to allow better application in practice. Many factors can influence the effectiveness of the PAP stimulus such as the time between the PAP stimulus and the performance to be measured, the individual's muscle typological profile (ie, the percentage of fast, slow fibers, etc.), the load or intensity of the PAP stimulus (eg, the percentage of 1RM that is used, the speed of movement, etc.), the type of muscular contraction of the PAP stimulus (eg, isometric, concentric, eccentric, etc.) and the training level of the athletes.

Handling PAP seems to be an interesting tool in disciplines where explosive and ballistic movements are paramount. However, it is necessary for each coach or physical trainer to proceed by trial and error to determine, for each athlete, what is the optimal recovery time to improve the desired performance. Many protocols have to be tested, all the secrets of PAP are still far from known.

References

  1. Kilduff LP, Cunningham DJ, Owen NJ, West DJ, Bracken RM and Cook CJ. Effect of postactivation potentiation on swimming starts in international sprint swimmers. J Strength Cond Res 25 (9) : 2418-2423, 2011.

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