I think if you are in good and above average condition it should be ok to workout heavy. However, I highly stress that you perform all the excercises and lifts with perfect form. If you don't, not only will you risk injury but you gains will be slow to nothing. Also, your lifting foundation will be weak. Many young lifters concentrate on putting more weight on the bar. They should be concentrating on their technique. If you don't your technique will only get worse, which means you will get injured and your gains will stop.