Gravity

When it comes to functional training and bodyweight training gravity is your friend...or foe, however you would like to look at it.  Basically gravity provides real time feedback of how your body responds to exercises and movements.  The faster you go, the more power you will create, the slower you go, the more gravity you will combat, creating more strength.  Once you understand this concept it is pretty easy to use gravity to your (dis)advantage for a significant workout.

Do a minute of squat jumps followed immediately by one minute of holding a squat in the downward position, with your fingertips just grazing the floor between your legs.  Notice how you prefatigue the quadriceps with the powerful jumps and then force your body to recruit slow twitch muscle fibers to keep you from collapsing as you hold that squat down for the second minute.  You get bang for the buck here, accomplishing power, strength, and endurance in just 2 minutes.

The same can apply with pushups.  Do one minute hard of explosive pushups, followed immediately by hovering above the floor in the lowest part of a pushup for another minute.  Note how gravity wants to suck you to the floor and how you recruit MUCH more out of your body to just hold yourself two inches from the floor.

Gravity is such an awesome factor in a bodyweight workout, use it to help you, you will never accomplish this real time feeling utilizing just machines.