Flexibility training is a fundamental biological process that improves the quality of life of the elderly by improving the ranges of motion of joints, postural balance and locomotion, and thus reducing the risk of falling. Two different training programs were assessed acutely and after 12 weeks by means of the sit-and-reach test. Thirty-one healthy older adults were randomly divided into three groups: the Experiment I group (Exp) performed strength and static stretching exercises; the Experiment II group performed dynamic and static stretching exercises; and participants assigned to the control group maintained a sedentary lifestyle for the entire period of the study. Flexibility acutely increased in Exp I by the first (ΔT0 = 7.63 ± 1.26%; ES = 0.36; p = 0.002) and second testing sessions (ΔT1 = 3.74 ± 0.91%; ES = 0.20; p = 0.002). Similarly, it increased in Exp II significantly by the first (ΔT0 = 14.21 ± 3.42%; ES = 0.20; p = 0.011) and second testing sessions (ΔT1 = 9.63 ± 4.29%; ES = 0.13; p = 0.005). Flexibility significantly increased over the 12 weeks of training in Exp I (ΔT0 − T1 = 9.03 ± 3.14%; ES = 0.41; p = 0.020) and Exp II (ΔT0 − T1 = 22.96 ± 9.87%; ES = 0.35; p = 0.005). The acute and chronic differences between the two groups were not significant (p > 0.05). These results suggest the effectiveness of different exercise typologies in improving the flexibility of the posterior muscular chains in older adults. Therefore, the selection of a program to optimize training interventions could be based on the physical characteristics of the participants.