The Effect of Time and Frequency of Static Stretching on Flexibility of the Hamstring Muscles
(First author is same as the other study on the time of stretching)
The purpose of this study was to determine the optimal time and frequency of static stretching to increase flexibility of the hamstring muscles, as measured by knee extension range of motion (ROM)
The results of this study suggest that a 30-second duration is an effective amount of time to sustain a hamstring muscle stretch in order to increase ROM. No increase in flexibility occurred when the duration of stretching was increased from 30 to 60 seconds or when the frequency of stretching was increased from one to three times per day.
“To participate in the study, subjects must have exhibited tight hamstring muscles, operationally defined as having greater than 30 degrees’ loss of knee extension as measured with the femur- held at 90 degrees of hip flexion.””
Does the result apply to people without tight hamstrings?
- >30 seconds?
- other muslces?
Insights, lessons learnt:
Not worth stretching more than once a day (at least for hamstrings)
Subjects: Ninety-three subjects (61 men, 32 women) ranging in age from 21 to 39 years and who had limited hamstring muscle flexibility were randomly assigned to one of five groups. The four stretching groups stretched 5 days per week for 6 weeks. The fifth group, which served as a control, did not stretch
To participate in the study, subjects must have exhibited tight hamstring muscles, operationally defined as having greater than 30 degrees’ loss of knee extension as measured with the femur- held at 90 degrees of hip flexion.”
Following the initial measurement, subjects were randomly assigned to one of five groups. Subjects assigned to group 1 (12 men, 6 women; mean age=24.44 years, SD=3.35, range=21-31) did three 1-minute static stretches (10 seconds between stretches) of the hamstring muscles. Group 2 (12 men, 7 women; mean age=27.32 years, SD=5.60, range= 21-31) did three 30-second static stretches, with a 10-second rest between stretches. Group 3 (12 men, 6 women; mean age=27.33 years, SD=7.60, range=21-39) did one static stretch for 1 minute. Group 4 (12 men, 6 women; mean age = 24.78 years, SD=2.37, range=22-29) did one static stretch for 30 seconds. The fifth group (13 men, 7 women; mean age= 27.20 years, SD=4.79, range= 22-36) served as a control group and did no stretching activities. Subjects in groups 1 through 4 stretched 5 days a week for 6 weeks.
As indicated by the post hoc analyses, increasing the duration and frequency beyond one 30-second stretch performed one time per day did not increase flexibility. The results of this study are similar to the results of our previous longitudinal study investigating the effects of duration of stretch,16 in which 30 seconds of static stretching was reported to be as effective as 60 seconds of static stretching in increasing flexibility of the hamstring muscles and more effective than not stretching. The use of longer duration and more frequent daily stretching, therefore, must be questioned