MTB Start intervals are a great way to improve your race starts. These workouts are an all out effort for 1-2 min, then zone 4-5 for 10 min. These will improve your speed at MTB races, either XC, Endurance, or 2-4 person relay events.
This chart shows a recent workout from a client. The session lasted two hours with 4 intervals. Each interval included 1 min of power zone 6, 120% FTP, and then 10 min of 105% FTP, then rest 10 min between intervals.
The graph shows the power (yellow) and heart rate (red). The spike at the beginning of reach interval is the 1 min zone 6. The rest is averaging 105% FTP. You can see a slight drop of the power and heart rate in the middle, this was from a decline on the course the interval was done on. Even with little deviation, the power was still right at 105% FTP.
If you are looking for a boost in your race starts, this is a good session to try. You should do at least 4 sessions leading up to the A or B race, but no more then one a week. It’s best to do these earlier in the week and when fresh. Allow for a recovery day (off or easy riding) after this session if racing the same week, or if you race Masters (40+).