Zackrisson et al. (2005) found that the current observations cannot rule out the possibility that these blue LSBGs formed as recently as 1-2 Gyr ago. Schombert et al. (2001) argued on the basis of their V-I colors and relative HI content that the most gas-rich LSBGs should typically have mean stellar ages below 5 Gyr. Padoan et al. (1997) and Jimenez et al. (1998) used UBVRI photometry to conclude that most of the galaxies in their sample appeared to be older than about 7 Gyr. Vorobyov et al. (2009) used numerical hydrodynamic modelling to study the long-term ($\sim$13 Gyr) dynamical and chemical evolution of blue LSBGs adopting a sporadic scenario for star forming. Their modelling strongly suggested the existence of a minimum age for blue LSBGs: 1.5-3.0 Gyr (from model B-V colors and mean oxygen abundances), or 5-6 Gyr (from model H$\alpha$ equivalent widths). The later value may decrease slightly if LSBGs host truncated initial mass functions (IMFs) with a smaller upper mass limit. Haberzettl, Bomans, Dettmar (2005) studied the star formation history of a sample of 7 LSBGs in the HDF-S. The comparison of measured spectral energy distributions (SEDs) with the synthetic spectra extracted from the synthesis evolution model 