The research objectives were to analyze: the effectiveness of static and dynamic stretching exercises for increasing flexibility; the effect of high and low muscle strength abilities on the flexibility of gymnastics athletes; and the interaction of the two types of exercise to increase flexibility in terms of muscle strength. The research method is a 2 x 2 factorial design experiment. The treatment is carried out for 18 times with 2 sets x 30s x 13 exercises, tr.ti: 90s: 2-3 minutes. The population as well as the sample, namely the rhythmic gymnastics athletes of Surakarta City, amounted to 20 people. The instruments used are back dynamometer and sit and reach. Two way ANOVA data analysis technique. The results showed that static stretching exercises had a better effect than dynamic stretching on flexibility in gymnastics athletes. Athletes with high muscle strength abilities were better than low muscle strength athletes with respect to flexibility. Static stretching is suitable for athletes with high muscle strength and dynamic stretching with low strength abilities.