Hi SantaFay,
The idea of pushback is an interesting one and while it is mentioned a lot on various sites … it is actually more about resistance and pressure than it is about pushback itself. Post #2 here goes into this in more detail. Once a body is at rest on any material … all the forces that are “pushing” in different directions become equalized and what a person feels at this point is the pressure or the weight that is being supported by each part of the body at rest. The body at rest only feels pressure … not the direction of the pressure (whether its push down with weight or push back with resilience).
In addition to this … latex is also more resilient (absorbs less energy) and has a higher sag factor (gets firmer faster with increasing compression) than other materials. The resiliency means that the foam “stores” more energy and “gives it back” when your body moves while memory foam “absorbs” more energy which turns into heat and doesn’t give it back when you move. Memory foam in other words “resists” movement more than latex while latex “assists” movement more than memory foam.
The combination of ILD, sag factor, resiliency, hysteresis (absorbing of energy), elasticity, point elasticity, viscosity, temperature sensitivity, and other factors (such as the cell structure itself, the breathability or resistance to the movement of air within the material, and even things such as creep which is the tendency of a material to relax over time) are what results in the “feel” of different foams and why each type of foam has different performance characteristics.
So what you feel as pushback would likely be a combination of pressure sensitivity in a certain area of your body along with the feeling (such as movement assistance) of the material itself. The pressure distribution part or “pushback” can be altered by changing the ILD and layering scheme or zoning of a particular foam. Other characteristics though (such as higher resiliency, lower hysteresis, sag factor, etc) are part of the nature of the material itself. This is why some people really like say a layer of soft latex over an innerspring but not so much the same layer of latex over a latex core. This is also part of the reason that someone try a HR polyfoam layer and compare it to a latex layer with the same thickness, ILD and sag factor but like the feel of one over the other even though by two of the most important measurements they seem to be very similar. In this case the latex could have a higher resiliency and a lower hysteresis as well as many other differences which results in a preference of one over the other.
So if the feeling of “pushback” is more connected to actual pressure relief or pressure distribution … then it would be a matter of adjusting the ILD or the layer thickness or the layer combinations of the latex. If it was more connected to the overall feel of the latex material itself, then of course this is a preference that would indicate other materials either in the comfort layers or in the support core or both. Innersprings for example have far more pushback than latex and store more energy but their feel is different than latex because of the many other differences between how foam and steel (which only compresses in one direction) react to pressure. For some people, more pushback (progressive resistance) than latex can provide may be desirable in a mattress core for their “feel” preference but less “pushback” in a mattress comfort layer (say memory foam or a lower ILD of latex) may be much closer to their desired feel.
While latex is a great material and can provide very similar pressure relief to other materials including memory foam in certain ILDs and layering schemes … it is certainly not the preference of all people in its other “specs” and when it comes to personal preference no matter how they are described … there is no right or wrong here.
With the Spring Air Natures Rest (who do make mattresses that are all Talalay latex as well as other types) and with the Sleep Options (made by Classic Brands who use various combinations of latex and polyfoam) it would be important to know the layering of each mattress which would help a lot in determining whether the feeling of pushback you experience is more related to the latex itself or to the “adjustable” qualities of latex. For example if someone lay on a polyfoam comfort layer that was 50 ILD and it was way to hard for them (which it would be for most people), then this is one of the adjustable qualities of polyfoam and if they described polyfoam as being “too hard” they would probably avoid all polyfoam altogether because they would connect polyfoam to “hardness”. So while latex as well as other materials can have a huge variety of different variations … they also have common characteristics among all the variations and there is no material that can provide for the preferences of all people.
This is part of the “art and science” of mattress construction, and even mattress testing, and why it is so much fun … and frustrating at times :). Combining objective qualities of each material with objective needs and subjective preferences of each person and differentiating between them can certainly be difficult. In the end though … at least IMO … its well worth it.
Phoenix