The Menstrual Cycle and Your Performance
By
Stacy Sims, M.S.
of
Peak Running Performance
With all the changes in hormone levels that occur during your
menstrual cycle, you'd expect speed workouts to suffer during your period,
right? Wrong. Surprisingly, near the end of your period, your body is
actually geared to pegging track workouts and tempo runs. However, your
long, slow runs will suffer. Read on to learn how your training and racing
is affected by your menstrual cycle.
The Fluctuation of Your Energy Levels
Your menstrual cycle is composed of three phases. The first phase,
generally days one through thirteen (the first three to seven days being
menstruation), is called the follicular phase and is marked by relatively
low levels of estrogen, except for a spike near day fourteen. The next
phase, called ovulation begins on day fourteen . The remainder of the
cycle, days fifteen through 28 of the average 28-day cycle, is called the
luteal phase and is characterized by moderately high and stable levels of
estrogen.
Estrogen levels are important because estrogen is the key hormone
affecting not only your cycle, but also the type of fuel available for
your working muscles. Studies have shown that low levels (in the
follicular phase) favor the breakdown of quick energy stores (muscle
glycogen) whereas high levels (in the luteal phase) favor fat-burning,
lower lactic acid levels and glycogen sparing.
How Does This Relate to Training?
Say you've planned your track workouts for every Wednesday. You go to
the track during your follicular phase (low estrogen) and hit all your
repeats right on. You leave the track with confidence and excitement. A
few weeks later, you go to the track but you're now in the luteal phase
(high estrogen). You feel sluggish, tired and lethargic. You feel like you
have a totally different body. You leave the track doubting your abilities
and your training program, despite the fact that your long runs have been
successful. Don't feel discouraged, though. It's not for lack of training
that you're performing this way, it's the way your body is fueling your
workouts.
In the follicular phase you benefit from a quick breakdown of
carbohydrates for speed and efficiency. Your body is primed for providing
quick energy for fast running In the luteal phase, however, your body is
in the fat-breakdown mode -- fueling your workout primarily through
increased utilization of fat. Since fat is a source of slower, more
sustained energy than carbohydrates, your intensity may suffer during the
luteal phase. Basically you're trying to run high-octane workouts on
low-octane fuel.
In other words, during the luteal phase your long, slow runs will feel
easier and require less recovery time because your body will take
advantage of increased fat breakdown. In the follicular phase your tempo
runs and interval training will feel easier because you'll be accessing
quick energy through carbohydrates.
Of course, this doesn't mean you shouldn't do long-distance workouts in
the follicular phase or tempo workouts in the luteal phase. Just keep in
mind that faster running may feel harder in the luteal phase, while slower
running may feel more difficult in the follicular phase.
With this new understanding of your menstrual cycle and the fueling
mechanisms that change from phase to phase, don't view your cycle as a
training disadvantage but rather a training secret. Use what nature gave
you as your ergogenic aid and have confidence in your training. Sorry,
men, but maybe estrogen is the wonder hormone after all!
References:
Brooks, Exercise physiology (2nd ed.), Mayfield, 1996
Medicine & Science in Sport & Exercise, Vol. 22, 1990
Medicine & Science in Sport & Exercise, Vol.19, 1987
Scandinavian Journal of Medical Science & Sports, Vol.1, 1991
International Journal of Sports Nutrition, Vol. 4, 1994
Journal of Applied Physiology, Vol. 51, 1981
The Physician & Sports Medicine, Vol.14, 1986
Clinics in Sports Medicine, Vol.13, 1994
European Journal of Applied Physiology, Vol. 69, 1994
