— based on https://augustams.com/erectile-dysfunction-exercises-health/

For men who have been unable to achieve an erection for multiple years this (learning the pump) can be a two-week commitment to reconditioning blood vessels in the penis to handle blood.

Regular use of the Soma Therapy ED vacuum therapy device will create penile rigidity. Daily penile rigidity through erectile dysfunction exercise will duplicate the benefits of nocturnal erections, reversing penile shrinkage, reconditioning penile tissues with blood circulation and promoting a return to good penile health.

“If you don’t use it you lose it.”. My Chinese book (P159) also says “用进废退”.

For prostate cancer, other treatments (beside prostatectomy) can also cause ED as side effect (though prostatectomy has the highest chance). If you are serious about erection, then beware prostate cancer.

— https://augustams.com/physical-activity-to-improve-erectile-function/ described aerobic and other exercises

The term used by Urologist to describe erectile dysfunction exercises is penile rehabilitation.  Penile rehabilitation programs are like a form of physical therapy.  These programs help men recover their erectile function by inducing erections to “exercise” the penis.

— penis shrinkage (beside ED) due to aging, celibacy or other reasons

“If they don’t do anything to maintain normal erections, they will get shortening of the penis,” Kohler says. Without regular erections, penile tissue can become less elastic and shrink, making the penis 1-2 centimeters shorter.

If you don’t get frequent erections where your penis and its skin stretches you may lose some (perceived) length to the penis.

Research has also shown that long periods of impotence or celibacy can result in some loss of size to the genitals

Excess belly fat can …making it appear shorter. Can also create real barrier for penetration, exactly like ED.

Dr Teo was convincing — For patients recovering after prostatectomy, VED is routinely prescribed to give them erections. Dr Teo performed implant surgery on many patients, and had difficulty putting in a longer prosthesis for some unfortunate patients — their penis lost length permanently, because no erection for a “long time”.

— importance of nightly erections .. https://www.healthline.com/health/benefits-of-taking-viagra-daily

“The penis is a unique organ. During the day, there’s very little blood flow in the penis… All the other organs are getting the 100 mm of oxygen all day and night, but the penis doesn’t… The penis only gets arterial blood flow during erections and during sleep. So from the perspective of the penis, sleep is the real time when oxygenation occurs.”

Goldstein noted that having good nighttime erections can help “prevent the scarring of the penis” that normally occurs with age.

Ultrasound gives us the ability to assess the degree of scarring in an individual, Goldstein said.

“Taking a PDE5 inhibitor every night can magnify the night erections and increase the chance of oxygenation, which increases the chance of getting rid of that scar tissue.”