Spotting is more common in longer cycles. A womans vulva may swell just prior to ovulation, especially the side on which ovulation will occur. One of the groin lymph nodes (on the side on which ovulation will occur) will swell to about the size of a pea, and may become tender. Causes
Mittelschmerz is believed to have a variety of causes:

Follicular swelling: The swelling of follicles in the ovaries prior to ovulation. While only one or two eggs mature to the point of being released, a number of follicles grow during the follicular phase of the menstrual cycle (non-dominant follicles atrophy prior to ovulation). Because follicles develop on both sides, this theory explains mittelschmerz that occurs simultaneously on both sides of the abdomen.Ovarian wall rupture: The ovaries have no openings; at ovulation the egg breaks through the ovarys wall. This may make ovulation itself painful for some women. Fallopian tube contraction: After ovulation, the fallopian tubes contract (similar to peristalsis of the esophagus), which may cause pain in some women. Smooth muscle cell contraction: At ovulation, this pain may be related to smooth muscle cell contraction in the ovary as well as in its ligaments. These contractions occur in response to an increased level of prostaglandin F2-alpha, itself mediated by the surge of luteinizing hormone (LH).Irritation: At the time of ovulation, blood or other fluid is released from the ruptured egg follicle. This fluid may cause irritation of the abdominal lining.
Most of the compounds stabilize the hypoxia-inducible transcription factors which activate the EPO gene. The compounds include oxo-glutarate competitors, but also simple ions such as cobalt(II) chloride.Inhalation of a xenon/oxygen mixture activates production of the transcription factor HIF-1-alpha, which leads to increased production of erythropoietin and improved performance. It has been used for this purpose in Russia since at least 2004. Cycling
Recombinant EPO is believed to have come into use in cycling about 1990. In theory, EPO use can increase VO2max by a significant amount, making it useful for endurance sports like cycling. Italian antidoping advocate Sandro Donati has claimed that the history of doping in cycling can be traced to the Italian Dr Francesco Conconi at the University of Ferrara. Conconi had worked on the idea of giving athletes transfusions of their own blood in the 1980s. Donati felt this work "opened the road to EPO . . . because blood doping was a trial to understand the role of EPO".Dr. Michele Ferrari, a former student and protege of Conconi, had a controversial interview mentioning the drug in 1994, just after his Gewiss-Ballan team had a remarkable performance in the La Flèche Wallonne race. Ferrari told lEquipe journalist Jean-Michel Rouet that EPO had no "fundamental" effect on performance and that if his riders used it, it would not "scandalize" himself.