Around one in three UK women of reproductive age take the contraceptive pill.

The pill is around 99% effective in preventing pregnancy (if taken correctly), it can reduce the length of periods, make them lighter, and helps combat painful periods as well as the dreaded psychological effects of PMS.

But in taking a hormonal contraceptive pill, we’re altering our monthly cycle – and our hormones. How does that affect cycling performance?

There’s very little research on the topic – but we know Dr Stacy Sims, who created Osmo Nutrition for women, knows her stuff – so we asked for her opinion.

The gist of it?

Oral contraceptive pills invoke 6-8 times the estrogen and progesterone levels that a naturally cycling woman has. Thus all the negative effects of estrogen and progesterone are elevated.

Read on to find out what that means for competitive women…

Let’s start at the beginning – what effect do natural female hormones have on performance? 

Women have an altered energy metabolism during exercise which completely impacts how we recover. Our recovery window is smaller and we have a predisposition to become over trained if we do too much intensity at different times during the cycle.

So – when are we predisposed to becoming over trained, and which hormones cause this? 

During the menstrual cycle, we have two hormone phases: high and low.

During the low hormone phase, our carbohydrate metabolism and recovery is the same and we are able to complete high intensity workouts.

During the high hormone phase, estrogen reduces the availability of carbohydrate and increases the amount of fat used for fuel; thus we have problems hitting intensities. Elevated progesterone increases our core temperature by ~0.5’C, increases total body sodium losses, and increases muscle breakdown (and at the same time, reduces the body’s ability to synthesize muscle).

If this wasn’t enough, the combination of elevated estrogen and progesterone drops our available plasma [which transports nutrients around the body] volume by around 8% ; and with concurrent shifts in baseline thresholds, makes us more predisposed to hyponatremia [low sodium induced bonking].

How do these hormones affect our training through the month? 

• If we count day 1 of the natural cycle as the first day of bleeding, then the first 1-14 days are great for hitting PRs in power moves, intensity/speed, strength, skills
• As we approach ~days 15-18, the surge of estrogen with slowly rising progesterone will reduce our ability to hit high intensities, increase our central nervous system fatigue and we kind of lose our “mojo”; it is here where I tell women to start a focus toward endurance
• Days 22-28 (the 5-7 days leading up to bleeding) I emphasize recovery type workouts if possible.

What does all this mean for women on the pill? 

There are several kinds of oral contraceptive pills (OCPs).

• Monophasic – these provide a steady level of estrogen and progestin across the three active weeks.  Alesse, Loestrin, Ortho-cyclen, Seasonale, and Yasmin are all examples.
• Biphasic – these provide steady estrogen, increasing levels of progestin the second 2 weeks of active pills. Examples include Kariva and Mircette Ortho-Novum 10/11 .
• Triphasic – these provide increasing levels of estrogen and progestin across the three weeks of active pills – brands include e Cyclessa, Ortho Tri-Cyclen, Nortel 7/7/7, Enpresse, and Ortho-Novum 7/7/7.
• And the “mini-pill”- which uses progestin only

Oral contraceptive pills invoke 6-8 times the estrogen and progesterone levels that a naturally cycling woman has. Thus all the negative effects of estrogen and progesterone are elevated.

Moreover, for those who have a fourth ‘sugar pill’ week – the “low hormone” week is actually NOT low hormone as the body rebounds to estrogen levels similar to the first trimester of pregnancy.

Are there any alternative hormonal contraceptives that have a lesser effect? 

Alternatives include the “ring” (NuvaRing), which is a localized [released where it matters, and has less effect on your entire body] contraceptive option that releases estrogen and progestin during placement. A hormonal IUD is also localized with small doses of progestin released during placement.

The progestin only aspects of the Ring and an IUD are not as impactful as they are more localized doses of progestin, but this introduced hormone still affects muscle integrity and recovery.

Other alternatives include a copper IUD, and of course barrier methods such as condoms. 

Would information like this cause you to consider swapping the pill for another method?