A good way to improve your lactate acid threshold is performing "all out" rows on the concept 2 rower. This is also a good protocol to monitor your level of fitness. This is a very simple protocol and is done by performing a 5 minute "all out" rowing season on the concept-2 rower. Rowing is a very complex skill and it works all major muscle groups of the body. It will leave you exhausted after a 5 minute burst.
Try completing this all out 5 minute test once a week and try to increase the distance covered in 5 minutes every week for 10 consecutive weeks. Make sure you are recovering well during this time and your regiment is programed well to avoid over training. The goal is to increase the distance covered in each 5 minutes row test every week.