Is it permissible to wear shorts that show part of my ‘Awrah – the knee – in front of men like me during training?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

The majority of scholars are of the opinion that the man's ‘Awrah (bodily parts which must be covered) extends from the navel to the knee – and this is the preponderant opinion. The navel and the knee are not included in the ‘Awrah, and it is conditioned that the dress is neither tight to reveal the ‘Awrah nor transparent to show the skin of the ‘Awrah just by glancing at it without staring.

Consequently, it is permissible to wear those shorts as long as they reveal nothing above the knee, as you mentioned. That is because the knee is not part of the ‘Awrah, according to the preponderant opinion. You should also observe the other conditions of the Islamic dress stated above.