There is a guy who puts resistance bands under and around a bench press bench and performs a bench press with weight on the barbell and the added resistance of the bands as he pushes up. He also does the same type of thing with dead lifts. It sounds unsafe to me. What do you have to say about this type of exercise?
Unsafe...? Possibly, though ANY exercise can be unsafe if performed by a particular individual at an inappropriate time. Albeit in this case, the bench press and deadlift are more extreme examples. To put the notion of "unsafe" into perspective, a basic floor bridge (bodyweight supine hip extension) may be "unsafe" for the hypolordodic individual with facilitated glutes and inhibited hip flexors, which is very common by the way. Perhaps the more appropriate question is, "What's the goal?" Consider the following points:
In the aforementioned bench press and deadlift, the natural resistance curve of these two exercises is such that as the working levers (the arms in the bench press and the legs/hips/spine in the deadlift) gradually become "straighter" during the concentric portion of the movement(s), the extrinsic resistance (the barbell in this case) gradually becomes lighter, biomechanically speaking. In essence, the line(s) of resistance created by the barbell travel straight through the levers (arms, legs/hips/spine) in the "lockout" position(s), naturally creating a "lightened" load.
This has to do with what is known as the "moment arm" of the resistance. The moment arm of an exercise/movement can be defined as the shortest distance between the axis of rotation and the line of resistance that is perpendicular to that line of resistance. Please see the diagram at left demonstrating the moment arm in elbow flexion (dumbbell bicep curl). The "sticking" point of a given exercise is generally where the moment arm(s) of the resistance of that particular exercise is the longest, thereby creating a greater load.
Applying a resistance band/elastic tubing to the equation will in some large or small part (depending on the thickness of the band/tubing) work to reverse the natural resistance curve mentioned above. This is due to the nature of an elastic medium of resistance, which will naturally increase/crescendo as the ROM increases and the band/tubing is stretched. So essentially, in the lockout position of the bench press and deadlift, where the resistance offered by the weights has decreased, the resistance offered by the band/tubing has increased. Naturally then, these resistance curves are reversed during the eccentric phase of the movement.
Caution should be taken here, specifically with regard to sport specific power training where an implement of some sort is "released" such as in baseball, hockey, shot putting, etc. Elastic types of resistance have been shown to activate the body's natural "breaking" mechanisms due to the direct (i.e., opposite of "inverse") relationship between the body's own natural ROM and the increase in elastic resistance. Research has shown that training the body to "break" when it should be at its peak in power production can and has led to overuse type injuries such as shoulder/elbow tendonitis and others.
If the individual you've been observing has progressed himself appropriately regarding flexibility, stability, strength and power, then he may be in no danger at all and may be simply going for variety in his training or perhaps basic muscle confusion. Remember the strength training principle of VARIATION is crucial to help prevent staleness and pattern overload.
- Chek, P. Program Design: Choosing Reps, Sets, Loads, Tempo, & Rest Periods.
- Purvis, T. Resistance Training Specialist Manual.