Hi, this is Kiya, exercise scientist and creator of WEightless Worldwide, the evolution of mind body fitness. Isometric exercises are a great way to activate your deep core muscles and work in a real and a natural kind of way. The very definition of weightless fitness. Sub-maximal exercise simply means that you're not working to your maximum capacity. So, take your foot of the gas just a little bit, and your at about 60 to 70 percent of your maximal output. Three of my very favorite sub-maximal isometric exercises are the plank, downward facing dog and table top. The reason I like all three is that one is inverted, one really hits the front body, and the other really hits the back body. So these three exercises together will give you a total body isometric workout. Start with downward facing dog. Keep the knees bent, the heels do not need to touch the ground. If you straighten your legs, you're gonna activate a stretch receptor that is gonna keep you stiff for the rest of your workout. So keep it loose in the beginning, breathe into your body and press out of your shoulders. If you want, you can add a little bit more bend in the knee, or a little bit more straightening of the legs in order to get a stretch at the same time. Bend the knees, wave forward into your powerful plank position, activating the lats, the big muscles underneath your armpits, and power into the low portion of your pelvis or your transverse abdominals. Exhale, flip over into your tabletop position, move your fingers facing your body, and move your heels in about three or four inches away from your pelvis. Lift your hip bones towards the sky and feel your back body activate. Downward facing dog, plank and tabletop are three of my very favorite sub-maximal exercises, and together they will give you a total body isometric workout, the very definition of weightless fitness.