Stretching isastimulationofmusclegrowth.Stretchingforhoursordayshasaneffectonmusclehypertrophy.However,differences
ofcontinuousstretchingandrepetitivestretchingtoaffectmusclegrowtharenotwellknown.Toclarifythedifferenceofcontinuous
and repetitive stretching within a short duration, we investigated the gene expression of muscle-related genes on stretched skeletal
muscles. We used 8-week-old male Wistar rats (푁 = 28) for this study. Animals medial gastrocnemius muscle was stretched
continuously or repetitively for 15min daily and 4 times/week under anesthesia. After stretching, muscles were removed and total
RNA was extracted. Then, reverse transcriptional quantitative real-time PCR was done to evaluate the mRNA expression of MyoD,
myogenin, and embryonic myosin heavy chain (MyHC). Muscles, either stretched continuously or repetitively, increased mRNA
expression of MyoD, myogenin, and embryonic MyHC more than unstretched muscles. Notably, repetitive stretching resulted in
more substantial effects on embryonic MyHC gene expression than continuous stretching. In conclusion, passive stretching for a
short duration within a week is effective in increasing myogenic factor expression, and repetitive stretching had more effects than
continuousstretchingforskeletalmuscleonmusclegrowth.Thesefindingsareapplicableinclinicalmuscle-strengtheningtherapy.