The aim of this study is to examine the immediate effects of hamstring stretching intensity on muscle strength, flexibility, muscle elasticity, and lower extremity function.
The study involved 12 participants aged 18-25, randomly assigned to three groups: low-intensity stretching (LIS), moderate-intensity stretching (MIS), and high-intensity stretching (HIS). Participants were selected based on hamstring flexibility below 80 degrees and predominantly using their right leg. Stretching intensity was determined using a visual analog scale with the following classifications: Mild (1-3), Moderate (4-6), and Severe (7-10), which were explained in the first session.
The stretching protocol consisted of three sets 30-second repetitions, where participants performed hip flexion of their dominant leg while lying on their back, using a belt for assistance.
Assessments were conducted before and immediately after the stretching protocol, evaluate lower extremity muscle flexibility, strength(hand held dynamometer), elasticity (MyotonPro), vertical jump test, the Y Balance Test (YBT), and a 20-meter running test.
For statistical analysis of the interaction between pre- and post-stretching assessments across groups, a Repeated Measures Analysis of Variance was employed.
The average age of the 12 participants was 22.4 ± 1.56 years, including 7 males (58%) and 5 females (42%). Their average height was 169 ± 8 cm, weight was 66.91 ± 16.5 kg, and body mass index (BMI) was 23.26 ± 4.99 kg/m², with no significant differences in these measures across groups (p > 0.05).
In the 20-meter speed test, the high-intensity stretching group showed a significant improvement over the low-intensity group (p = 0.08). In the Y Balance Test (YBT) posteriomedial direction, significant differences favored the high-intensity group compared to both low-intensity (p = 0.039) and moderate-intensity groups (p = 0.017). For hamstring muscle strength, a significant difference was observed between low- and high-intensity stretching (p = 0.03).
Significant differences in muscle stiffness and elasticity were also noted in favor of the high-intensity group for Semitendinosus-F (muscle tone) (p = 0.049), Semitendinosus-D (muscle stiffness) (p = 0.032), and Semitendinosus-R (muscle elasticity) (p = 0.023). There was a significant change in other measurements before and after stretching, but there was no significant difference between the groups.
The study suggests that while high-intensity stretching may improve lower extremity performance there were no significant differences observed in other measures between the stretching protocols. This indicates that both high- and low-intensity stretching can be beneficial for athletes, depending on their specific goals, while high-intensity stretching may offer additional advantages for performance enhancement and injury risk reduction.
The results imply that both high- and low-intensity stretching can effectively enhance athletic performance and reduce injury risk, suggesting that personalized stretching protocols may be beneficial in rehabilitation and training programs.
muscle tone
muscle elasticity
