ReferenceDuffery,
MJ and Challis,
JH. Fatigue Effects on Bar Kinematics During the Bench Press. J Strength
Cond Res 2007;21:556-560
AbstractThe bench press is one of the most popular weight training exercises. Although most training regimens incorporate multiple repetition sets, there are few data describing how the kinematics of a lift change during a set to failure. To examine these changes, recreational lifters (10 men and 8 women) were recruited. The maximum weight each subject could bench press (1RM) was determined. Subjects then performed as many repetitions as possible at 75% of the 1RM load. Three-dimensional kinematic data were recorded and analyzed for all lifts. Statistical analysis revealed that differences between maximal and
submaximal lifts and the kinematics of a
submaximal lift change as a subject approaches failure in a set. The time to lift the bar more than doubled from the first to the last repetition, causing a decrease in both mean and peak upward velocity. Furthermore, the peak upward velocity occurred much earlier in the lift phase in these later repetitions. The path the bar followed also changed, with subjects keeping the bar more directly over the shoulder during the lift. In general, most of the kinematic variables analyzed became more similar to those of the maximal lift as the subjects progressed through the set, but there was considerable variation between subjects as to which repetition was most like the maximal lift. This study shows that there are definite changes in the lifting kinematics in recreational lifters during a set to failure and suggests it may be particularly important for coaches and less-skilled lifters to focus on developing the proper bar path, rather than reaching momentary muscular failure, in the early part of a training program
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My ThoughtsAn interesting little piece of research that provides a little more evidence supporting the differences that load and fatigue can create to the bench press. Basically the researchers collected a bunch of trained people, got them to perform a 1rm test in front of a camera, then wait 5minutes and perform a set to failure at 75% of that 1rm.
During this time, the researchers videoed the movement to enable the examination of bar speed and position in the horizontal movement plane. They then compared the figures for the 1rm to all of the reps achieved in the set to failure.
The first rep of the set to failure was relatively dissimilar to the 1rm attempt. The major differences was the bar position at the bottom, the groove it followed on the way up, as well as the obvious overall movement speed. Looking at a chart of the bar velocity during the first and last sets of the set to failure, as well as the 1rm test shows an interesting, but relatively known concept.
At 75%, a rep is completely different to the 1rm. A 75% rep is performed fast, with no apparent sticking point, and one peak in bar velocity that occurs at the end of the movement with lockout. Both the final rep, and the 1rm test appear similar, except the initial peak of velocity is higher in the 75% set. There are two peaks, one during the initial drive off the chest, and the other at lockout. Bar speed is slower on the 75% sticking point, but since the load is lower the lifter can struggle
throught. The slowest point of the entire upwards movement occurs at 30-50% of the lift phase, which matches older research showing the sticking point is 25-40% of the lift.
While this research does not provide any actual intervention knowledge, it allows us to look at a little bit of specificity of training. If you want to learn the best groove for a move, a 1rm will be the best teacher for a 1rm. However, training near 1
RM's is difficult. Performing reps at 75-85% will result in a groove that is different to the 1rm, however, do more reps and the ultimate movement looks a lot more like a 1rm. This effect can start as early as in the first 10% of a set, or typically occurs at 70-85% of the sets progression. So within a set of 10 to failure, the 7th, 8th and 9th rep would be the most like a 1rm test.
Maybe this is why a sets of three/five are great building points for strength. Most of these sets are close to failure, but not quite there. So a lot of the reps would be performed in a moderately fatigued state, matching the groove for a 1rm test. Same as performing high volume training, where the last sets are done in a relatively fatigued state, or providing a training environment that is more representative of 1rm lifting, without the maximal loading. Proving that this is more efficacious for improving strength is a different story.
