The question is that for a 37 years old man is it normal to have a decrease in ejaculation power (semen force or shooting of semen)? And how may this problem be treated and solved?
As you get older, it's perfectly normal to notice a decrease in ejaculation power. But, at least you can still get hard and can reach ejaculation! I guess what I'm trying to say is... it could be worse?
In all seriousness, it's not that big a deal, and if you work at it, you can regain your full power. What would you do if you realized you couldn't throw a ball as far as you used to? You would exercise the muscles you use when throwing.
The muscle you want to target and work out is the pubococcygeus muscle, or PC muscle. It's a pretty important muscle for good sexual health. When you need to stop pissing mid-stream, you naturally flex the PC muscle.
Once you identify it, try to do a series of exercises every day. try flexing it, and holding it tense for 10 seconds and then release. Repeat this until you get tired. The next day you might be able to it a few more times because it will be getting stronger. Google PC muscle, or male kagel exercises, for more info on these fun little workouts.
One final note Moral, this could be a symptom of some prostate problems, or other more serious health problem, so use your discretion, and consider talking with your doctor.
But, probably not. So, get out there and have some fun! With your penis!