Menstrual cycle and strength: what the research says
Does the menstrual cycle affect women’s strength and muscle endurance? Swedish sports medicine researchers took a look at this question — and the answer surprises many: your menstrual cycle doesn’t take away your strength.
Why the menstrual cycle and strength are a topic at all
Many women feel more tired, heavier and unmotivated on certain days. That’s a real experience — but does it mean the muscles are actually weaker? It’s important to distinguish between subjective perception and measured results.
This question has been studied repeatedly in sports medicine. Swedish researchers followed 15 moderately active women over two consecutive menstrual cycles. Hormone levels were checked in both blood and urine in three different cycle phases. In parallel, strength and muscle endurance were tested separately in each phase.
The result? No measurable changes were found.
What the menstrual cycle actually changes — and what it doesn’t
The findings of the Swedish study were confirmed by another, similar study that followed 19 women over three menstrual cycles. There too, strength and endurance stayed stable regardless of cycle phase.
Hormones — estrogen and progesterone — really do fluctuate considerably over the course of the cycle. These fluctuations affect mood, energy levels and fluid retention. But the contractile strength and endurance of the muscle stay the same. In that sense, the body is a surprisingly stable machine.
Honestly, that’s good news. It means you don’t have to skip your workout on the second weekend of your cycle with an excuse. Your body is capable of reaching the same result as at any other time.
If your menstrual cycle seems to take your strength — what’s actually going on?
If you hit a wall on the bench press or the barbells feel painfully heavy — that’s a real experience. But the cause is probably elsewhere.
- Insufficient sleep. Hormonal fluctuations disrupt sleep — and the effect of poor sleep on strength is well documented. Even one bad night noticeably reduces performance.
- Undereating. In the second half of the cycle, the basal metabolic rate rises slightly. If you eat the same amount as usual, you may be in a bigger calorie deficit than you think.
- Fluid retention and bloating. The body feels heavier — that’s subjective, but it affects training psychologically.
- Pain and discomfort. Cramps, back pain — these disrupt concentration and motivation, even if the muscle itself is working normally.
A simple truth: if you have a tough day in the gym, first ask yourself — have I slept enough? Have I eaten enough? These two factors explain most bad training days, regardless of cycle phase.
FAQ: menstrual cycle and workouts
Can you work out during your menstrual cycle?
Yes, absolutely. Studies show that strength and endurance don’t drop in any phase of the cycle. If you feel up to it, train as usual.
Do hormones affect training at all?
Hormones affect sleep, mood and energy levels — which in turn affect training indirectly. Studies don’t confirm a direct effect on muscle strength.
What should you do if you feel bad during your cycle?
Listen to your body. Light movement and stretching always work. If you really feel bad, a rest day is justified — but don’t assume your muscles are to blame.
Author: joker
Source: WHO – physical activity.
Come and train! ArtGym
