Exercise in moderation

Sometimes exercise can contribute to infertility. It is possible to be “too fit.” Women who work out intensely can have trouble getting pregnant, possibly because reproductive hormones are suppressed when the body interprets excessive calorie burning or physical stress as danger which can interfere with ovulation.

Women who over-exercise are at risk for losing too much body fat. Body fat helps to produce estrogen. Women with too little body fat may not ovulate regularly.  Many women who over-exercise experience oligomenorrhea, or they may even develop amenorrhea- and stop getting a period entirely. At this point, it is difficult –if not impossible, to conceive a child.  The body may be saying “whoa” when there is too little fat to sustain a growing baby.

The effects of strenuous exercise on fertility can be related to reduced progesterone production during the luteal phase of the menstrual cycle.  Low levels of progesterone can interfere with a fertilized egg implanting, which leads to infertility. Another potential cause for exercise-induced infertility is changes in leptin levels, which regulates appetite and metabolism.  Long term intense exercise raises adrenaline levels while depressing leptin levels.  Adrenaline will eat away at stored sugar or glycogen, as well as fat stores.  When body fat gets too low, your menstrual cycle will cease.  When your leptin levels decrease, your appetite may decrease as well.  If your appetite is low, you may not eat enough, which can interfere with regular ovulation.

It is also possible that women who exercise more than 7 hours per week are more likely to restrict their diet. Not eating healthy fats, losing weight rapidly, or weighing below the recommended weight guidelines for your height can affect ovulation. Overtraining can put extra stress on the body.  Even if you still have your period, fatigue, soreness, insomnia or poor performance are signs that you are overtraining. A study published in Obstetrics and Gynecology found that those who regularly exercised 4 or more hours/week were 40% less likely to conceive after their 1st IVF treatment than less active women.  “Even with exercise, too much of a good thing can be bad.”

Men who over-exercise can cause the internal temperature of testicles to rise. Typically testicles remain at a temperature of 96 degrees.  If testicles become warmer than this, sperm begin to die leading to a low sperm count. Men who over-exercise and become underweight can also experience low sperm motility and poor sperm morphology.  Being underweight creates a shortage of testosterone, which affects sperm production as well.  Biking is a particular concern in terms of male-factor infertility both because of the tight-fitting training clothes worn during the sport, as well as the constant, prolonged contact between the saddle and the testicles.


A woman should aim for a body fat percentage in the range of 20 to 25% and a body mass index (BMI) of 20 to 25. That would equal about 117 to 145lbs. for someone 5’4” tall. If you BMI is over 27, and you’re trying to lose weight, you should get involved in an exercise program.

Fertility in Women & Men Who Don’t Exercise Enough

While too much exercise is a problem for some women, there are more women with the opposite problem – not enough exercise, possibly leading to obesity.  Research shows that being overweight can impair fertility. Obese women tend to have more fat in their bodies.  This fat can increase the amount of estrogen inside your body. This can influence ovulation, menstruation, and conception in a negative way. Women who are overweight also tend to be more resistant to insulin.  Insulin resistance can force your body to  produce excess levels of insulin, which can inhibit ovulation. Being overweight puts women at risk of such pregnancy complications of high blood pressure, diabetes, and abnormally large baby. 

Regular exercise may help you lose weight and regulate your hormones.  These positive changes in your body can promote regular ovulation, which can increase your chance of conceiving.  Studies have shown losing 10% of your current body weight will help fertility in women.

A recent study found that overweight men who have a BMI of 26 to 28 (approx 175-205lbs and 5’9” frame) were 50% more apt to be infertile than men at a healthy weight.   Obese men had a greater risk.  Excess fat may increase the temperature of the scrotum, thereby reducing sperm quality, and can also raises the estrogen level, which lowers sperm counts.  A  5’9” male should aim for a BMI of 19 -25, or 130 -170lbs.

Exercise Can Help Relieve Stress

Trying to get pregnant can be very stressful, both physically and mentally.  Couples get extremely caught up with fertility treatments, such as IVF or IUI, and other parts of their lives tend to suffer as a result.  Unfortunately this is not a good thing when you are trying to get pregnant.

While stress may not be directly related to infertility, it can push us towards unhealthy behaviors. Stress can make it difficult to be intimate with your partner.  It can trigger other health problems, such as cardiovascular problems and depression.  It can interfere with ovulation and menstruation as well as sperm health and motility.

Stress can affect ovulation.  Several hours before ovulation, the pituitary gland normally sends out a surge of LH, which causes the ovary’s follicle to release an egg.  Stress can signal the pituitary gland that your body is in trouble, which slows the release of LH, which may disrupt ovulation.  Even if ovulation occurs, a shortage of LH could mean a shortage of progesterone, which is necessary to nourish and sustain a fertilized egg.

Exercise can be a great stress reliever and is very helpful in restoring hormonal balance and fertility.  Exercise releases endorphins, which encourages your body to better deal with pain and stress.  Exercisers tend to manage stress better and have less stress than non-exercisers.

Exercise & fertility FAQ’s

When Should I Begin an Exercise Program?
All adults should avoid inactivity. Some physical activity is better than none, and adults who participate in any amount of physical activity gain some health benefits.  For inactive adults (less that 75 minutes of activity/week), start by building 10 minutes of structured activity into your day. Consider walking or swimming. If it is difficult to carry on a conversation, slow down.
How Often Should I Exercise?
Exercising 30 minutes a day, three to four days a week can stimulate fertility and help you conceive.
What Types of Exercise are Recommended to Increase Fertility?
There has been debate over the years about whether or not certain exercises can actually increase your fertility.  To date, there is no evidence that one form of exercise works better than others. Because yoga poses increase blood flow to certain organs, it may help to stimulate ovulation and make the uterus more receptive to conception.  It is also known to be a stress-buster.  Other types of exercises recommended are walking, swimming and low intensity biking.
At What Intensity Can I Exercise?
Everyone has different levels of exercise that may or may not interfere with fertility.  Research suggests that moderate physical activity in women improves time to pregnancy across the range of BMI.  An inverse association between vigorous physical activity and how long it took to become pregnant was found for women with a BMI < 25.  In women with a BMI >25 there was no association between vigorous exercise and a longer time to pregnancy. This suggests that in women with a normal BMI, vigorous exercise can be counterproductive, while in overweight women intense exercise does not impair or delay achievement of pregnancy.

Weight and BMI should be monitored. If weight loss occurs and your BMI is already within the “normal range” of 19 – 24, or is <18, caloric intake should be increased. If weight gain occurs, and your BMI falls into the overweight/obese categories (25 – 30+),  re-evaluate your intake.  It is not recommended to have rapid weight loss or gain.

Those who exercise more than 7 hours of intense workouts may want to cut back.  Consider replacing some of your workouts with gently yoga or leisure walking.  Serious athletes may have to add more calories to their diet and reduce the intensity and amount of exercise.

If a woman has an established exercise program prior to treatment, that level may be maintained and continued with some minor modifications and reasonable precautions.

What Exercise Modifications Do I Need to Make During a Treatment Cycle?

Avoid overheating during exercise, hot tubs, hot yoga, and exercising during very hot days.  Activities such as horseback riding, vigorous racquet sports, downhill skiing or contact sports should be avoided.  Any activity that increases your risk of falling, bumping or hitting your abdomen is not recommended.  No scuba diving.  Bouncing activities such as vigorous step aerobics and running will increase your risk of ovarian torsion particularly 5-7 days after stimulation.  Avoid jostling tender ovaries.  Aim for a target heart rate of 120-130 bpm from stimulation to one week post transfer.  If an activity is uncomfortable, don’t do it!

Can Exercise for Men Increase Sperm Production?
Yes. Physically active men who exercised at least three times a week for one hour typically scored higher in almost all sperm parameters in comparison to men who were sedentary or who participated in highly vigorous exercise. Extreme exercise causes oxidative stress which can damage sperm. A research study examining the effect of exercise on men showed that bicycling more than five hours per week has a correlation with both lower sperm counts and lower sperm concentration.[ii]