Easier said than done. Just use a door anchor, you might say. I'm afraid door anchors
are only safe when pulling the door closed. Typically that means you are outside of
the room in a narrow hallway.
2. Anchor safety
Let's say you give up and attach an anchor to the wall with metal hardware like screws.
Then start training vigorously. Uh oh, you have created a powerful sling shot
waiting to propel metal hardware towards you at high speed when the anchor fails.
3. Consistent resistance
Bands give variable resistance depending on how far they are stretched. This means
that your loading will vary wildly depending on how far away you stand from the
anchor. Not a good thing if you are trying to increase load in small and predictable
increments.
4. To each action there is a reaction
If you pull on a band attached to an external anchor, the reaction force has to go
through the floor. Otherwise you would pull yourself towards the anchor. This will
require good friction between your feet and the floor. Even the best soft rubber
will give friction a bit less than your own weight. I can row more than that.
5. Balance
Even if your feet stay put on the floor, you will have to brace to not topple
over like a bowling pin. This further limits the force that you can exert.
Typically you will have to lean back, which changes the angle of the exercise
into something else.
6. Don't accept limits
In resistance training, the target muscle should be the limiting factor. Not the
friction on the floor, or your ability to brace against the external anchor.
7. Objects may be lighter than they appear
OK, so can I at least pull UP on bands attached to band pegs ? Unless the rack or
bench are super heavy, or attached to the floor with SOLID anchors, you may be able
to pull it up quite easily. A semi-strong person can isometrically pull three times
bodyweight or more. Do the math.
How to make it work ?
Use your feet, your back or a foot plate as the anchor.