Changes in Insulin-Like Growth Factor 1 and Quadriceps Muscle Size in FollicularStage Compared to Luteal Stage in Adaptation to Resistance Trainingin Young Women

Menstrual cycle may affect the training of strength and muscle size. The aim ofthe present study was to determine the effect of exercise volume distribution in the 2 follicular and lutealphases of the menstrual cycle on serum Insulin-like Growth Factor 1 (IGF-1) and muscle mass in women.

in this semi experimental study’ 20 amenorrheic women with a mean age of 22±5 years, withoutcontraceptive use and a history of eight weeks of resistance training were selected. Each subject had8 training sessions on one leg in the first 14 days of menstruation and 2 training sessions on the second14 days of menstruation (training in the follicular period) and the other leg had 2 training sessions on thefirst 14 days of menstruation and 8 training sessions on the second 14 days of menstruation (training inthe luteal period). The training protocol was consist of unilateral leg extension.

the quadriceps Muscle diameter (according to pretest size) in follicular training (FT) (0.67±0.34(cm)) was higher than luteal training(LT) (0.46, 0.41 cm) (P=0.012). Also, insulin-like growth factor increasedin both groups (13%) regardless of the type of exercise schedule (P> 0.001).

According to this study it is recommended that follicular based training may cause more musclehypertrophy and maximum strength than luteal based training in young amenorrheic women whodo not take birth control pills.