If you are training with intensity, this is more then enough time. Any longer and you are not only failing to train hard enough, but you will begin breaking down muscle tissue and negating the positive muscle building effects. If you train for 60 minutes or more, it is highly recommended you consume simple carbs and amino’s during training to increase your anabolic state and performance. So, it is important to listen to your body. Get adequate rest or expect muscle growth to be a very long process as your body requires adequate time for optimal recovery so it can rebuild and repair the damaged muscle.