Have you ever heard of the "Hold Out and Clench Your Teeth For Maximum Testosterone" theory? Basically, this strategy is based on the idea that if you can somehow avoid ejaculation, you will experience a dramatic increase in testosterone. And, believe it or not, there is some science behind it. One study out of China examined 28 male volunteers and observed a clear spike in testosterone beginning on the 7th day (or darn close).  Furthermore, the spike was huge - 145% of baseline.
So is this a good way to overcome low testosterone and even hypogonadism? Below I'll outline a number of reasons that, as interesting as the research is, this is probably not a practical way to help men in their quest for more testosterone:
This was a very small study and one can't help but wonder at the very large increase observed. Increasing T by 145% is no easy task. For example, weight lifting, CPAP machines for apnea sufferers and other similar lifestyle changes usually only increase testosterone in the 15-30% range.There are several other studies showing abstinence from ejaculating leading to elevated testosterone levels. One was very old  and one involved a three week period of "holding out" - ouch!  So, yes, this is a way, for younger men anyway, to raise testosterone. However, below I outline four reasons that I think non-ejaculation is a poor option for men:
1. Impracticality . The authors noted that "a peak [occurred] on the 7th day of abstinence; and that the effective time of an ejaculation is 7 days minimum." So let's say that a man waits to ejaculate for 10 days. According to this study, he will have his regular T levels for 7 days and then experience a dramatic increase that will continue until he ejaculates for a few day until he ejaculates on the 10th day. This means that a) if he is in a relationship, he has avoided sexual relations for most of it and b) he only gets 3 higher T days out of 10.
2. Sex Is Good For You. Sexual intercourse is excellent for male health. Furthermore, a couple of studies have shown increases in baseline testosterone from regular intercourse. Sex is also very important for most health relationships. So is abstinence for 7 days really going to improve your health? The majority of studies would seem to indicate the opposite.
3. Hypogonadism. The men who I have seem following this "7-Day Abstinence Approach" have very low testosterone or are even hypogonadal. It is very questionable that this approach will achieve the same degree of success as it did with random volunteers. Generally, hypogonadal men have some sort of dysfunction of either the testes, hypothalamus or pituitary. Abstinence is simply trying to "squeeze blood out of a turnip," i.e. there is nothing there in the first place.
4. Morning Erections. Another important point related to #4. Many men with low T have stopped experiencing regular morning erections. This means 7 days without ejaculating will likely mean 7 days without an erection. This is very hard on the internals of the penis as the corpus cavernosum, the spongy containers that hold the blood within the penis, need regular oxygenation to stay healthy and flexible. For more information, see my link on The Importance of Morning Erections.
1) J Zhejiang Univ Sci, 2003 Mar-Apr, 4(2):236-40, "A research on the relationship between ejaculation and serum testosterone level in men"
2) ARCHIVES OF SEXUAL BEHAVIOR, 1976, 5(2):125-132, "Orgasmic frequency and plasma testosterone levels in 3) WORLD JOURNAL OF UROLOGY, 2001, 19(5):377-382, "Endocrine response to masturbation-induced orgasm in healthy men following a 3-week sexual abstinence"