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Effect of bench shirts on bench press performance

par P. Debraux | 11 January 2018

powerlifting, bench press, shirt, muscle, strength, performance, speed, science, sport

Initially designed to limit the risk of injury and accidents when performing the bench press movement, bench shirts quickly became tools for performance. There are different models, usually characterized by their material, placement of seams and tissue thickness. Their role is supposed to allow athletes to lift heavier loads.

The bench press is a weight training exercise. In powerlifting, the bench press is one of the 3 main movements. It consists of lying on your back on a flat bench with your head, shoulders and butts in contact with the surface of the bench, and your feet flat on the floor. The arms are in an extended position and hold a loaded bar vertically. After the starting signal of a judge, the movement is executed by flexing the upper limbs to bring the loaded bar into contact with the chest. Again, at the signal of a referee, the athlete will have to extend the upper limbs to return to the starting position (i.e., arms locked in an extended position).

The powerlifting is a discipline based on maximum muscular strength, the goal is to lift the heaviest loads on 3 movements which are the squat, the bench press, and the deadlift. To achieve these 3 movements, athletes can use different equipment approved by I.P.F.. such as shirts, belts, suits or wraps, for example. For more information on powerlifting, visit the official website of I.P.F..

Figure 1. Bench shirts Inzer and Titan tested in this study.

The Study

A study conducted at the University of Reims Champagne-Ardenne (France) consisted of observing the differences in terms of performance (i.e., loads raised) and speed of execution of the movement during a bench press exercise with and without bench shirt. Two shirts were used in this study: an Inzer "Phenom" shirt with seams on the shoulders and a Titan "Fury" shirt with seams under the triceps brachii (Fig. 1). These tests were realized with a sample of 11 french national strength athletes.

To compare the effects of bench shirts, the researchers analyzed, for each condition (i.e., without and with shirt) three variables:

  • The maximum load moved
  • The average speed during the concentric phase (i.e., the "push" phase of the bar)
  • The maximum speed during the concentric phase

Each condition was tested one week apart and the conditions for determining the maximum load were similar to those of a competition. In addition, it should be noted that the speed measurements were made with a load equal to 90% of the maximum load without shirt.

For data acquisition, an opto-electronic three-dimensional motion analysis system (Vicon Mx, UK) was used. This system allows for 3D kinematic analysis (e.g., acceleration, speed, displacement, angles) of the human body thanks to several special cameras placed around the capture zone.

Results & Analyzes

The results of this study are presented in Table 1:

Unsurprisingly, this study demonstrated on a sample of 11 athletes that the use of a bench shirt improves the performance in terms of loads moved and speed of execution. In this sample, the Titan "Fury" shirt seems to allow, significantly, the best performances. Figures 3 and 4 show the average differences between the different shirts and the "no shirt" condition, a heavier load of 19% and a higher average running speed of more than 38% for the Titan "Fury".

Différence d'influence des maillots d'assistance sur la charge maximale déplacée en développé couché en comparaison avec la condition 'sans maillot'.

Figure 2. Difference of influence of the bench shirts on the maximum load in the bench press in comparison with the condition 'without shirt'.

Différence d'influence des maillots d'assistance sur la vitesse moyenne et la vitesse maximale lors de la phase concentrique en développé couché en comparaison avec la condition 'sans maillot'.

Figure 3. Difference of influence of the bench shirts on the mean and maximal speed during the concentric phase of bench press in comparison with the condition 'without shirt'.

But why does a bench shirt improve performance and speed anyway...?

Figure 4. If you pull on both sides of an elastic at rest (1), it stretches (2). While stretching, it exerts a force to return to its initial length.

That the shirt improve performance in the bench press will not surprise the strength athletes, but why? Finally, what a simple shirt made of cotton, polyester or denim could do? (Note, however, that denim shirts are not allowed by I.P.F.)

Well this bench shirt can bring additional elastic potential energy...

Elastic potential energy

This notion will be detailed later in the biomechanics of sport and exercise course.

But what is elastic potential energy? To put it simply, consider the example of an elastic band (Fig. 4). At rest, it has a certain length. Pull on its ends at the same time, and the elastic will lengthen. Nevertheless, when you do this you feel some resistance. And the more you pull on the elastic the more this resistance increase. Finally, if you release the elastic it quickly gets back to its original length.

During the strain, the elastic has stored elastic potential energy. This energy is said to be potential because it can be returned and transformed into kinetic energy. It is this energy that helps the elastic to return to its original shape.

And as surprising as it may seem, it is the same principle that applies in the example of the bench press and the assistance shirt. Yes, the shirt is not made of rubber (this is specifically prohibited by I.P.F.), But we will still talk about elasticity. It must be understood that the term elasticity is not limited to rubber elastics, but applied to all materials. However, it is obvious that a wooden board will have less elasticity than an elastic band...

And this is the most interesting part in the case of the bench shirt: it is not very elastic! The deformation of the whole shirt-arm (i.e., to lower the bar) (Fig. 5) requires a great deal of energy. This elastic potential energy will be returned to allow the shirt to return to its original shape (i.e., to raise the bar) (Fig. 6). Of course, the shirt is not everything. But as the results of this study show, the difference between performance without and with shirt may be quite impressive.

Figure 5. Eccentric phase during bench press. The bar applies a force on the athlete and on the shirt (represented by the red arrows), and this will cause a deformation of the shirt.

Figure 6. The shirt is strongly stretched. During the descent of the bar, it has deformed and stored elastic potential energy that will be restored as kinetic energy, and therefore helps the athlete to raise the bar in the initial position.

Applications pratiques

The bench shirt is a tool for performance. The criteria for choosing a shirt are multiple. On a mechanical level, the deformation of a rigid shirt will produce more elastic potential energy. Nevertheless, a shirt too rigid could cause discomfort and a change in the movement pattern, which could affect the performance. And a shirt too soft will not bring any benefits.

The bench shirts come in several materials, and different models according to the style of bench press of the athlete. Specialists generally recommend testing shirts over a more or less long period to get used to them.

Finally, it may be interesting for coaches to test athletes with different bench shirts using field equipment such as portable accelerometers. In that way, they could objectively assess the effects of different shirts and how they are affecting the performance.

Références

  1. Herrgott S and Bertucci W. Effet de l'utilisation d'un maillot de force sur la performance et la cinématique du développé couché. Sci Sports 22 : 162-162, 2007.

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