When working to build muscle fast you should be working at 80% of your one-repetition max(1RM)
You should be doing between 8-12 repetitions, meaning that a set would last between 2-3 minutes
Always aim for more repetitions, once you have achieved 12 reps of 80% of 1RM add more weight and repeat this cycle for best gains.
Disclaimer
The content of this blog post is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment. Information regarding supplements has not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary.