Animal studies show that long-lasting stretching training can lead to significant hypertrophy and increases in maximal strength. Accordingly, previous human studies found significant improvements in maximal voluntary contraction (MVC), flexibility and muscle thickness (MTh) using constant angle long-lasting stretching. It was hypothesized that long-lasting stretching with high intensity will lead to sufficient mechanical tension to induce muscle hypertrophy and maximal strength gains. This study examined muscle cross-sectional area (MCSA) via magnetic resonance imaging (MRI). Therefore, 45 well-trained participants (f: 17, m: 28, age: 27.7±3.0 years, height: 180.8±4.9 cm, weight: 80.4±7.2 kg) were assigned to an intervention group (IG) that stretched the plantar flexors 6x10 minutes per day for six weeks or a control group (CG). Data analysis was performed using two-way ANOVA. There was a significant Time x Group interaction in MVC (p