Dr. Cammisa at Ultimate Chiro Care, where I go to use the Biodensity machine, suggested trying a Tabata routine during the week. Tabata is intense interval training, done in 8 sets of 20 seconds of sprinting, etc. at maximum capacity with 10 seconds rest after each sprint. Tabata training has been shown to increase anaerobic capacity, which should help with the isometric exercises done on the Biodensity machine.
I've tried Tabata a few times on an elliptical at home and once on a recumbent bike at the gym. Definitely gets me out of breath with muscles burning. However, it's hard to maintain the all-out effort for the entire 20 seconds, especially after two or three sets. It's very challenging. I'm trying to keep it up 3 days a week for a month. At least it's a very quick workout, even adding the recommended 5-minute warm up, 3-minute cool down and some stretching afterwards.