To be the best in your given field you need to train hard and push through pain and never give up but, there are so many athletes that do not know when to take the day off. By ignoring some of the smaller signs and pushing through illness you will surely find yourself overtrained.
Elevated Resting Heart Rate: You should record your HR every morning prior to getting out of bed, this gives you some insight into how your body is recovering. An elevated HR of 5-10 BPM more than your usual RHR could mean you are not fully recovered or illness may be setting in. Take the day off and monitor your HR the following morning; multiple days may need to be taken off if your HR remains elevated.
Muscle soreness after 72 hrs: If you still find yourself sore 72 hours after a training session there is a good chance you pushed a little harder than normal, this soreness is an indication that your body is still recovering from your previous training session so it is probably a good idea to take it easy or possibly take the day off if you are unsure.
Insomnia: You get stronger during recovery, if you are not getting the proper amount of sleep due to restlessness you will go into our next training session having not fully recovered. Insomnia post exercise can be caused by an overworked hormonal and nervous system.
One of the hardest parts of training for most athletes is taking time off due to illness or signs of over-training. Keep yourself busy during the time that you would spend training, give your bike a good wash or even a service if you have the tools. Keep in a good routine even during times of illness and always listen to your body…it knows best.