Why would the R2cv be higher than the R2cal?

I'm running Raman Spectroscopy data through the PLS Toolbox to predict various parameters of meat and I am continually getting R2cv values a lot higher than R2cal values. The toolbox is set to cross validate using leave- one- out cross validation with 20 maximum LVs and I have 80 samples.

For example, predicting tenderness using Raman Spectra has given me R^2 Cal: 0.00102829 R^2 CV: 0.288515.

Any ideas as to what could possibly be going on or how I can make sense of it would be much appreciated.