Good question. I've heard of 37 and 38 year olds still playing but I haven't seen one lately. My team, the Dog River Riverdogs, still carry Jose Nickerson, a 36 y.o. former league MVP, on our squad, but with the loss of several skills, he normally plays only in early-season Cup games and in scrimmages.  
                                
                                
                                
                                
                                
                                
                                    
                                       
                                        
                                    Pappy