How is a woman's performance effected by her menstrual cycle?
Men's hormones don't fluctuate wildly on a monthly basis like a woman's do. Women experience changes in estrogen and progesterone throughout the month that can affect their mood and reduce their motivation to do things - like work out. Some women say they don't feel like exercising a few days before their period and have to almost drag themselves to the gym, but does it really have an impact on what they're able to do? Can a woman's exercise performance fluctuate based on where she is in her cycle?
Menstrual Cycle, Hormone Fluctuations and Resistance
You may not feel like lifting hard the week before your period, especially if you experience bloating and weight gain. But the effects may be more psychological than physiological. According to a study published in the Clinical Journal of Sport Medicine, strength and muscle endurance aren't affected by where a woman is in her menstrual cycle. Bottom line? You won't have to use the little pink weights just because you're premenstrual. Your muscles still work just as well.
What about Aerobic Performance?
The luteal phase of a woman's menstrual cycle is the two week period that extends from the time of ovulation to the beginning of the next menstrual period. During this time progesterone levels rise along with body temperature.
One study found that women have a slight decrease in V02 max during the luteal phase. Since V02 max is a measure of aerobic capacity, this may translate into a slight decline in aerobic exercise performance, which may be more pronounced during the week before menstruation when fluid retention is greatest. Some women gain 5 pounds or more during this time, which makes them feel heavy and less motivated to maximize their workout.
On the other hand, some women may be at increased risk for injury at certain times in their cycle, particularly runners. Research shows that the risk of ACL injuries in women rises around the time of ovulation. Women are already at a 3 to 8 times greater risk for ACL injuries than men for unknown reasons. Women who take birth control pills don't seem to have the same increased risk of ACL injuries around the time of ovulation, suggesting that hormones play a role.
Exercise and the Menstrual Cycle
One bright spot is that exercise helps to relieve premenstrual symptoms. Even though the motivation to work out may be lower, as little as 20 minutes is a mood booster and helps to relieve the insomnia. It also helps to ward off fatigue and reduce irritability and anxiety. It's one of those cases of "just do it." You'll feel better afterwards.
The Bottom Line?
Most women don't experience a significant decrease in performance around the time of their period, especially when it comes to strength training. Exercise has a lot of positive benefits for premenstrual women, so there's no reason to skip just because it's the wrong time of the month. Think of it as therapy.
Clinical Journal of Sport Medicine. July 2003. "Muscle Strength and Endurance Do Not Significantly Vary Across 3 Phase of the Menstrual Cycle in Moderately Active Premenopausal Women"
Med Sci Sports Exerc. 1995 Mar;27(3):437-44.
Am J Sports Med March 2002 vol. 30 no. 2 182-188.