Do soft surfaces vs hard surfaces really matter?

Avocado's Number wrote:

Stopme99 wrote:

Newton’s Third Law only applies when the structural make-up of surface can support the applied forces. Equilibrium occurs when Newton’s 3rd Law is satisfied. A bridge that can hold up cars is an example of equilibrium. A hole in the drywall that was punch is an example of an absence of equilibrium.

No, Newton's third law applies whenever objects interact. Doesn't matter whether the bridge holds up the cars or crashes to the ground (or water) below. Doesn't matter whether the punch to the wall results in a hole in the wall, a metacarpal break in the hand, or a fusion of the punching hand and the punched object, as in the tale of Br'er Rabbit and the Tar-Baby.

True. Though Newton's 3rd Law can be broken in non equilibrium situations. This is where my argument of nonreciprocal forces apply to runner surfaces. When running on grass, the sum of internal forces don't equal zero.

LateRunnerPhil wrote:

It's not just about impact, but Salazar said it's better bang for the buck. On trails, the feet and leg muscles get a much better, versatile training than on asphalt and concrete where each foot strike is a replication of the previous one.

gotta agree on this. i'll do tempo runs on an asphalt path that has a dirt shoulder. when i switch from the shoulder to the path, i speed up without doing much else. I get enough asphalt in that i think doing some speed on the dirt is an advantage when it comes to race day.

I havent read any of the other posts, but here are my 2 cents:

It's important to at least get some running on soft/uneven surfaces each week to keep your small little balancing muscles active and strong - the muscles on your legs help protect your bones and joints from the pounding forces and therefore injury. I will sometimes do loops and loops and loops of grassy fields and artificial turf on my easy days for this purpose. Otherwise I just make sure to do 1 or 2 regular days/week on some sort of trail that requires a bit of looking down so you don't roll your ankle.

Along the same vein, don't just exclusively do trail runs. If that's all you're used to, your body will really be in for a big shock if you ever are forced to do a longer run on hard surfaces.

If you are racing on grass/dirt, it is important that you do at least some workouts on grass/dirt, so your body gets used to that pace over those surfaces, it's going to be a little harder than on the track/road.

If you are racing on the track, it's not as important, the focus is track workouts, duh.

If you are racing on the roads, it's important to make sure that you do some of your longer workouts on the roads so your body gets used to the pounding.

Every step is a collision. Softer surfaces decrease the force endured by the body during the collision.

Run on grass as much as you can.

Stopme99 wrote:

Avocado's Number wrote:

No, Newton's third law applies whenever objects interact. Doesn't matter whether the bridge holds up the cars or crashes to the ground (or water) below. Doesn't matter whether the punch to the wall results in a hole in the wall, a metacarpal break in the hand, or a fusion of the punching hand and the punched object, as in the tale of Br'er Rabbit and the Tar-Baby.

True. Though Newton's 3rd Law can be broken in non equilibrium situations. This is where my argument of nonreciprocal forces apply to runner surfaces. When running on grass, the sum of internal forces don't equal zero.

Newton's 3rd law cannot be broken. Ever. Forces can be balanced or unbalanced, but there is no breaking Newton's 3rd Law.

Whether running on grass or on concrete, a runner still (a) has their foot strike the surface, (b) slow down and then stop, and then (c) bounce back upward.

The difference between grass and concrete is that on grass, the time required for (b) to occur is longer. The grass "gives" a little, which means the foot takes more time to stop (or in physics terms, "accelerate").

Newton's 2nd Law says that F = ma, where F= force, m = mass and a = acceleration.

Since grass takes the foot longer to stop, the acceleration of the foot goes down. Using F = ma and assuming the mass of the runner is constant, you can see that if a decreases, F will decrease as well.

The softer the surface, the less force the body endures.

The difference between trail, grass, turf, track, cement, asphalt are pretty exaggerated. There is a difference though.

Train specifically.

I think a cambered cement road, undulating side walk asphalt, or uneven technical trail leave more room for disaster than surface density.

JohnNgugi wrote:

Newton's 3rd law cannot be broken. Ever. Forces can be balanced or unbalanced, but there is no breaking Newton's 3rd Law.

This is true for classical phenomena, not quantum, however.

sub_3_is_the_goal wrote:

JohnNgugi wrote:

Newton's 3rd law cannot be broken. Ever. Forces can be balanced or unbalanced, but there is no breaking Newton's 3rd Law.

This is true for classical phenomena, not quantum, however.

Negative Mass?