Max and group by query help
Try 

SELECT 
  tblTraining.clientTrainingID AS lastID,
  MAX( tblTraining.trainingDate ) AS lastDate
 FROM tblTraining
 WHERE tblTraining.trainedID =37
 GROUP BY tblTraining.clientTrainingID
 ORDER BY tblTraining.clientTrainingID desc
 LIMIT 1 


This will order the max() and limit the result to the first line being the highest value.