Isometrics and over 50

My wife(see the accompanying photo) and I have been experimenting with isometrics. I really do believe that they are underrated. I used to do them as a preteen with the Exergenie that I had begged my mother to buy me. I rediscovered them a year ago during my knee rehab. After doing some more research, I am going to make them a regular part of my workout. They do not put undue stress on the connective tissue and they seem to make significant inroads on the neural system and its role in strength development. If you do the movement in three different positions then you take care of the problem of the 20 degree range of strength improvement. I do deadlifts, military press, and curls - 3 different joint angles for ten seconds each. For three weeks, we have experimented with "long duration isometrics" with holds of approximately three minutes. These work strength, flexibility, focus, and mental toughness. One of the things that also recommends them is that they even out strength imbalances and the resulting compensation patterns.