During a set of curls, the tension in the biceps is constantly going up and down, like a sine wave. But this ideal angle only lasts for a split second. Imagine a barbell curl the hardest (and most productive) point of the barbell curl is when the forearms are at 90 degrees, parallel to the floor. So maybe now you're thinking, "Hell, I'm a bodybuilder, not a weightlifter or a martial artist. This is why the team at Dragon Door, with my help, invented the Isochain, the first-ever isometric chain-and-bar device with a digital readout display in the handle. The major issue here was that you couldn't see the meter during training, so you needed someone to call out the numbers. This problem was partially solved by the addition of a simple dynamometer to chain-and-bar devices. Sadly, without knowing how much you're lifting, progressive overload is pretty abstract, and tracking progress is difficult. How much force are you using? If you are pushing a barbell against pins in a rack you might know what's on the bar, but how much force is going into the pins? Nobody knew. The major argument against isometrics has always been the lack of measurement. Then, seemingly overnight, isometrics passed out of training culture. It seemed like isometrics were going to be the training method of the future.