Asthenospermia

While the commonest cause of male infertility is a low sperm count (the technical term for this is oligospermia), some men are infertile because of poor sperm motility.
Normally, at least 50% of sperm should be motile; and this should be good quality progressive motility.

When less than 50% of the sperms are  motile, the condition is called asthenospermia or asthenozoospermia (asthenia = weak).
While a lot of men with a low sperm count will also contain poor sperm motility (the two often co-exist, and this is called oligoasthenospermia), some man will have a normal sperm count, but very deprived sperm motility.
Sperm motility (whether the sperm are affecting well or not) can only be assessed when a semen analysis is performed in the laboratory.

Causes of Asthenospermia
1. Problems with sperm production - such problems can be genetic (for example Klinefelter's syndrome) or based on a hormonal disorder
2. Testicular injury and disease - injuries that affect the testicles may affect sperm production and cause low sperm count
3. Malnutrition and nutrient deficiencies - lack of some nutrients (for example Zinc, Selenium, vitamin C, etc.) may also lead to low sperm count
4. Overheating - excessive heat from saunas, hot tubs, etc. may decrease sperm production and lower sperm count
5. Smoking - smoking cigarettes may impair male fertility since it is known to reduce sperm count and sperm lifespan.