What You're Doing Isn't Strengh

When you lift or press a weight for 10 seconds, you deplete your first line of energy, called ATP: https://en.wikipedia.org/wiki/Bioenergetic_systems. The same thing happens when jumping or sprinting, or frankly even lower intensity exercise. It takes 30 seconds to recover 50% of the ATP. In 60 seconds, you may be 85% recovered. But it will take until 3-5 minutes to be fully restored.

If you are working at an intensity that will build strength, it is an immutable physical law that recovery is going to take beyond 60 seconds. Any effort which can be continued for minutes at a time and recovered from in less than 60 seconds is not strength. By definition, you aren’t training strength unless it takes 1-5 minutes to be prepared to replicate the performance. This is a biological fact, not a fitness opinion. And it cannot be overcome through will or “pushing it.” It’s a set chemical law of nature.

Walking is not strength. Raking leaves and shoveling isn’t strength. Tabata isn’t strength. HIIT isn’t strength. Circuits aren’t strength. Picking up 1lb or 2lb dumbbells isn't strength. Most popular fitness isn’t strength. It can’t be, by biological definition. If you persist beyond 10-15 seconds in an exercise, there is an immediate drop in power as you begin to call upon the glycolytic system (which will also begin creating lactic acid). This can sustain you until around 45 seconds, at which point you’ll suffer another drop in power (by 90 seconds you are firmly in aerobic territory). Thus, if you want to train to INCREASE power (ie - strength), you must remain pretty tightly in the 10-15 or at least sub-45 second efforts. AND to repeatedly do this will require REST, a MINIMUM of 60 seconds up to several minutes of rest in between. Over time, you increase the intensity, resistance, load AND rest times.

Real strength training DEMANDS rest. If you aren’t resting in between efforts, you aren’t strengthening. If you don't HAVE TO rest for minutes at a time, you aren't strengthening. 

Everything requires strength. Sitting in a chair requires strength. Holding a pencil requires strength. But they are not training increases in the capacity that is strength. Most activities are not TRAINING improvements or even maintenance in strength, because they are an intensity which can be done for longer than 45 seconds and require very little or no rest in between. If the intensity of something is low enough that you can continue it well in excess of 45 seconds, it isn't strength. If you can replicate that effort after only a few seconds of rest, it isn't strength. If you aren't consistently getting stronger, reducing pain, and improving life, what you're doing isn't strength.