espanolObjetivo: Examinar el efecto de la fase del ciclo menstrual en la potencia aerobica de futbolistas ASCUN de las Unidades Tecnologicas de Santander (UTS). Diseno: Observacional analitico tipo corte transversal. Metodos: 10 futbolistas nivel de competencia ASCUN entre los 18 y 23 anos, con un ciclo menstrual regular entre los 18 y 22 dias fueron reclutadas. Las deportistas fueron divididas de acuerdo a la etapa del ciclo menstrual en la que se encontraban el dia de la medicion ( etapa folicular y etapa lutea). La potencia aerobica fue evaluada mediante el test de course navette bajo las mismas condiciones por un evaluador debidamente entrenado y dos auxiliares para controlar el desarrollo adecuado de la prueba. Analisis estadistico: medidas de tendencia central y dispersion se utilizaron para la descripcion de las variables del estudio. Resultados: se evidencia un desempeno menor durante la ejecucion de la prueba de potencia aerobica en las variables de consumo de oxigeno maximo ( 33.8±4.31 ml/kg/min vs 38.3±2.28 ml/kg/min), distancia (740 ± 254.55 m vs 1013± 144.68 m ) y etapa alcanzada ( 5.4±1.41 vs 6.8±0.72 ) en las deportistas durante la fase folicular comparada con las de la fase lutea. Conclusion: este estudio piloto sugiere una influencia positiva de la fase lutea sobre la potencia aerobica de las futbolistas evaluadas; probablemente por el efecto de la progesterona en la facilitacion de los procesos de oxidacion en concordancia con lo reportado en la evidencia cientifica. EnglishPurpose: To examine the effect of the phase of the menstrual cycle on the aerobic power of ASCUN soccer players of the Unidades Tecnologicas de Santander (UTS). Design: A cross sectional study was conducted. Methods: Ten soccer players level of competition ASCUN, ages between 18 and 23 years, with a regular menstrual cycle between 18 and 22 days were recruited. The athletes were divided according to the stage of the menstrual cycle in which they were on the day of measurement (follicular and luteal stage). The aerobic power was evaluated by the course navette test under the same conditions by a properly trained evaluator and two assistants to control the development of the test. Statistical analysis: measures of central tendency and dispersion were used for the description of variables of the study. Results: a lower performance was reported during the development of the aerobic power test in the variables of maximum oxygen consumption (33.8 ± 4.31 ml / kg / min vs 38.3 ± 2.28 ml / kg / min), distance (740 ± 254.55 m vs 1013 ± 144.68 m) and stage reached (5.4 ± 1.41 vs 6.8 ± 0.72) in athletes during the follicular phase compared with those of the luteal phase. Conclusion: this pilot study suggests a positive influence of the luteal phase on the aerobic power of the athletes evaluated; probably due to the effect of progesterone in the facilitation of oxidation processes in accordance with what is reported in the scientific evidence.