The 3 x 20 SIT protocol uses what rest between intervals?

• A. 1 minute
• B. 30 seconds
• C. 2 minutes
• D. 4 minutes

Answer: (C)

Rest between intervals is chosen to allow enough phosphocreatine to be replenished after a 20-second maximal sprint. In SIT, you rely on the ATP-PC system for the short, high-intensity bursts, which depletes quickly and needs time to recover. Phosphocreatine resynthesis approaches substantial recovery in about 2 minutes, so a two-minute rest helps you perform the next 20-second effort at close to peak intensity. Shorter rests would leave PCr stores partially depleted and reduce sprint quality, while much longer rests aren’t necessary for this protocol and would make the session longer without added benefit. So, about two minutes of rest between intervals best supports maintaining high effort across all sprints.