Intervals are the backbone of structured training. Hard efforts, planned recoveries, repeated. Done well, they target exactly the fitness you need. Watch: Why Your Legs Stop Working | Energy Systems Ep.4. More on our YouTube channel. Set your zones firstEvery interval below uses a percentage of your FTP. Get yours from a test, then let our zones calculator do the maths. Heart rate lags behind effort in short intervals, so for anything under a few minutes go by power or feel. For longer, steady efforts heart rate works well as a check.Why intervals workYou cannot hold race pace for hours. Breaking hard work into chunks with recovery lets you spend more total time at the intensity you want to improve. Two 20-minute threshold efforts with a rest between give you 40 minutes at threshold. Try it in one go and most riders crack after 25. Each type of interval targets a different system, which is why the mix matters. See energy systems for the science.The main typesEndurance (56 to 75% of FTP)Not really intervals, but the foundation. Long and easy, building your aerobic engine, fat use and durability. Most of your riding should live here.Tempo (76 to 90%)Steady and purposeful. Good for long efforts like 2 30 minutes, and for practising race pace in a sportive. Watch it does not take over every ride.Sweet spot (88 to 94%)Just under threshold. Time efficient and great for building FTP. Read more on sweet spot training.Threshold (95 to 105%)Right on your limit for long efforts. Classic sessions: 3 10 or 2 20 minutes, with 5 minutes easy between. The core of raising your FTP.VO2max (106 to 120%)Hard efforts of 3 to 8 minutes that push your aerobic ceiling. Try 5 4 minutes with 4 minutes easy, or short intervals such as 3 sets of 13 30 seconds hard and 15 seconds easy. They hurt. They also work.Anaerobic (121 to 150%)Short, brutal efforts of 30 seconds to 2 minutes, with long recovery. For attacks, short climbs and closing gaps. Try 6 1 minute with 4 minutes easy.Sprints (maximal)6 to 15 seconds flat out with full recovery, 3 to 5 minutes between. Pure power. Quality matters more than quantity. More in how to sprint faster.Recovery between effortsLong efforts (threshold, sweet spot): around a quarter to a half of the work time.VO2max: roughly equal to the work time.Anaerobic: three to four times the work time.Sprints: full recovery. If the next one is slower, stop.How many interval sessions a week?Two or three hard sessions is plenty for most riders. More than that and the quality drops. Keep the rest easy, so you arrive at each hard session ready to hit the numbers.A sample weekTuesday: VO2max, 5 4 minutes.Thursday: threshold, 2 20 minutes.Saturday: long endurance ride with a few short sprints.Everything else: easy riding, gym and rest.How to get the most from themWarm up properly, around 15 minutes building through the zones with a couple of short openers.Hit the targets. Better to finish strong than fade on the last rep.Pick the right place: a steady climb, a quiet road, or the turbo.Fuel the hard days. See carbs per hour.Build gradually: more reps or longer efforts every week or two, then a lighter week.Write down how each session felt. Patterns show up fast.Matching intervals to your goalSportives and long rides: endurance, tempo, sweet spot.Time trials: threshold, sweet spot, long steady efforts. See time trialling.Crits and road races: VO2max, anaerobic, sprints, plus repeatability.Hill climbs: threshold and VO2max.Planning when to do which is where structuring your season comes in.Need a hand?Which intervals you need, and when, depends on your event and where you are starting from. A coach takes the guesswork out. Monthly coaching is 140, with a 15-minute call every week. Book a free 30-minute consultation.More from the blogHow to increase your FTPSweet spot training: what it is and when to use itHow to sprint faster on the bikeHow many carbs per hour when cycling?Saddle up.