private void CrearEjercicioBtn_Click(object sender, RoutedEventArgs e)
        {
            var win = new NuevoEjercicio();

            win.Show();
            Close();
        }
        private void EditarBtn_Click(object sender, RoutedEventArgs e)
        {
            var filaSeleccionada = ((FrameworkElement)sender).DataContext as Exercise;
            var win = new NuevoEjercicio(filaSeleccionada);

            win.Show();
            Close();
        }