Estrogen levels within menstrual cycles can affect training

Many women find workouts and runs more difficult from week to week and it can sometimes be a result of where they are in their menstrual cycle.

The menstrual cycle is divided into two main phases: the follicular and the luteal phases. During the follicular phase estrogen levels are low, which coincides with often easier, more enjoyable workouts. This phase will last for 14 days. On day 14 or 15 ovulation begins with a spike in estrogen and lutenizing hormone. The luteal phase lasts until the final day of the menstrual cycle, generally 28 days, and coincides with high levels of estrogen which can hinder performance, namely higher respiratory rates making fast, hard workouts difficult.

Low estrogen levels are ideal for burning glycogen stores which are used in high-intensity workouts. High estrogen is more suited to burning fat and longer, lower-intensity runs. As such, generally longer, slower runs are reported as being easier manage during the lutenizing phase when estrogen is peaking.

It is important for women to remember that hormone therapy and birth control can can alter hormone levels within the cycles or for extended timeframes.

Learning your own pattern and taking note of it can be useful for helping training and maximizing your potential for races and workouts.