When we are working out on a consistent basis it becomes necessary to make changes to the program. Depending upon the results being sought after. The prescribed amount of time between changes should be 6 – 8 weeks.
For my personal rotation, I am employing a combination of negative reps with concentric / eccentric reps. I will use this format with my dips and pull-ups. My attempt is to increase my strength for these two movements. In combination with my other movements, it should translate into overall (upper body) strength. This rotation will last for eight weeks.
My exercise regimen only contains two strength training days per week. I have two strength routines. The routine with the pull-up and dips is one time a week. I work to maximize core strength, posterior chain improvement and postural integrity. My workouts are not so much about muscular size as much as they are about movement efficiency and overall strength.
Considerations for negative training
Some studies show that eccentric contractions coupled with concentric / eccentric contractions produce greater hypertrophy than does isometric training alone. Negatives (Eccentric contractions) require the muscles to lengthen under tension. The muscles adapt physiologically to the increased tension. The lengthening under tension forces the muscles to contract while lengthening. The tension in the stretched muscle stimulates the smaller compartments of the muscle. These compartments take up more protein due to stress induced activation of protein building chemical pathways.
Science behind negative training
Negatives can be used to alter any exercise with or without weights. The exercise does not have to be stationary. Movements, when done slowly with intention, will positively stimulate the muscle fibers. Greater strength gains will be realized with external resistance. Also, Negatives can only be part of an overall training regimen.

I will document my workouts giving particular attention to these two exercises. I am experimenting with how my body will adapt to this change in my routine, seeing that I am older and do exercise as intensely as I once did.