The relation between recreational runners’ efficiency and particular phases of their menstrual cycle

Due to a changing level of hormones, menstrual cycle and its phases influence the performance of every fertile woman, either to a smaller or greater extent. Regarding the increasing popularity of endurance running, we have decided to put these two facts into context.
There are many reasons why women decide to begin with recreational running – it can be an attempt to improve their health condition, lose weight, or to shape their bodies. After getting into a community of runners, women usually become interested in enhancing their performances; they got involved in various-distance races; these women try to shift their average time and find a cause of their fluctuating efficiency.
As for this research, we worked with the data of 53 fertile women, who have decided to devote their free time to recreational, longer-distance running (at least 10 kilometres 3 times a week). Out of these 53 women, we have earmarked a group of 15 using hormonal anticonception. Subjects were observed during a period of three menstrual cycles.
Concerning the group without hormonal contraceptives, the period of the first half of the cycle (ovulation, day 14. – 16.), the secretory and menstrual phases of the menstrual cycle were evaluated. For each of these phases, we established a number of potential problems women could possibly perceive. Further on, changing running pace per kilometre was examined in every single phase, too. As for the most important part of the research, we evaluated how the particular difficulties could influence both the training and resulting performance.
With women using the hormonal anticonception, only the second part of the cycle was taken into consideration.