Why Do Sperm Swim?
Sperm are motile cells. This means that they are cells that make themselves move, which is important when it comes to fertility. For vaginal sexual intercourse to lead to conception, sperm needs to enter the body through the cervix and make its way to the fallopian tube to meet an egg. During intercourse, semen is ejaculated near the cervical canal, at the end of the vaginal canal. With normal motility, any semen ejaculated near the vaginal area can make its way up the vaginal canal and to the cervix. Semen can also get into the vaginal canal without ejaculation, from what is known as pre-ejaculate. This is a small amount of semen-like fluid that comes out of the urethra during sexual arousal. (This is one reason that the “pull-out” method doesn’t reliably work to prevent pregnancy.) Sperm are programmed to swim in a way that will help them reach their ultimate destination—the ovulated egg. While the egg is moved along from the ovary into the fallopian tube by tiny hair-like projections called cilia, the egg itself doesn’t swim. It floats into and through the fallopian tubes with the help of the cilia. Sperm, on the other hand, move themselves. They must swim up from the cervical canal, into and through the uterus, and, eventually, into the fallopian tube. This is where they meet an ovulated egg; the journey may take 10 minutes or so. Once there, the sperm must fertilize the egg, which also requires movement.
Sperm Motility and Overall Semen Health
Motility is just one measurement of sperm and semen health. Other factors considered during a semen analysis include:
Semen volume: How much ejaculate there is, which is measured in milliliters (mL)Total sperm count: How many sperm there are in the semen sample (average is 33 to 46 million sperm)Sperm concentration: How many sperm are in 1 mL of ejaculateVitality: Percentage of live spermSperm morphology: Shape of the spermTime to liquefaction: The time it takes for semen to naturally change from thick to liquidy (generally 20 to 30 minutes)Semen pH: The acidity of the semen sample (semen that is too acidic can kill sperm)White blood cell count: How many white blood cells are in the semen sample (a very high count can indicate infection)
Sperm Motility Measurements
If motility is the only problem, the odds of spontaneous (unassisted) pregnancy are better than if other issues are present.
Progressive Motility, Non-Progressive Motility, and Total Motility
How sperm move is also important. Progressive motility refers to sperm that are swimming in a mostly straight line or in very large circles. Non-progressive motility refers to sperm that move but don’t make forward progression or swim in very tight circles.
Percentage motile: What percentage of all the sperm in a single ejaculate are movingPercentage motile concentration: What percentage of sperm are moving in one measurement of semen, usually presented as millions of cells per mLTotal motile sperm count (TMSC): How many sperm are swimming in a single ejaculate (this number has been shown to be most relevant to male fertility prognosis)Average path velocity (VAP): The speed sperm are moving, measured in microns per second (μm/s)
Total motility refers to the percentage of sperm making any sort of movement. This movement can include non-progressive movement. For example, a sperm that just vibrates in place would be considered motile, but non-progressive. A sperm that zigzags but makes forward progression would be considered progressive. Progressive motility is needed in order for the sperm to swim their way up the female reproductive tract.
Percentage of Motile Sperm
In a person with normal fertility, one ejaculate of semen may contain over 39 million sperm. Not all of those sperm, however, are expected to be completely healthy. For an ejaculate sample to be considered normal, at least 40% of the sperm should be motile, or moving. This can include non-progressive movement. At least 32% of the sperm should show progressive motility. A diagnosis of poor sperm motility is usually made based on the percentage of motile sperm. However, research has found that the total motile sperm count is a more relevant measurement.
What Affects Sperm Motility
Usually, when sperm motility is poor, there are other problems found with sperm health. For example, people with poor sperm motility may also have low sperm counts or poor sperm morphology (or sperm shape). Sperm that aren’t formed properly can’t swim properly. Sperm motility may be harmed by exposure to chemicals, illness, exposure to heat or cold, lifestyle habits like smoking, or abnormalities of the male reproductive tract, like a varicocele. Poor sperm motility may also occur if a man has infrequent sexual activity. In this case, if the first ejaculate collected showed poor motility, a second ejaculate collected soon after should be better.
How to Improve Sperm Motility
Aside from treating any underlying medical conditions or genetic factors that influence sperm motility, there also are some lifestyle changes you can make to improve sperm motility. For instance, exercise regularly, eat a nutritious diet, limit alcohol, and quit smoking if you are a smoker. A meta-analysis of more than 20 studies found that people who smoke consistently have lower sperm counts. Another study found that those who use drugs and alcohol also experienced decreased sperm counts. While it is unclear if sperm motility will rebound if these lifestyle factors are changed, it certainly cannot hurt to try. There also is some evidence that consistent exercise can improve sperm motility. One study explored the benefits of a 16-week aerobic exercise program of at least three 50-minute sessions per week. Some of the participants experienced increased sperm count and motility. Eating a nutritious diet also may improve sperm motility. While the best approach is to eat an overall balanced diet of nutrient-rich foods, there is some evidence that some foods may have an impact on sperm motility. For example, one study found that foods rich in antioxidants like beta-carotene, beta-cryptoxanthin, lutein, and vitamin C may contribute to a healthy sperm count. Keep in mind, though, that no specific food is the key to increasing sperm count. Instead, focusing on the diet as a whole is the best way to improve fertility.
A Word From Verywell
Sperm motility is a measure of how many sperm are moving in one ejaculate sample. If sperm motility is something you are struggling with, you may want to consider making some lifestyle changes like exercising more and improving your overall diet. While these changes alone may not address the issue completely, they may help you improve your sperm’s motility. And, even if they have little impact, you are at least taking steps to improve your overall health. It’s also important to talk to a healthcare provider. They can help devise a plan that is right for you. You also can make lifestyle changes that could impact sperm motility, like quitting smoking, exercising more, eating a nutritious diet, and limiting alcohol. There is even some evidence in an older study that taking 200 micrograms of selenium along with 400 units of vitamin E for at least 100 days in a row can help. But you should speak with a healthcare provider before taking any supplements.
