Over Under Intervals

Over under intervals are structured tempo, sweet spot or threshold intervals with a harder, higher wattage effort at the beginning and the end of each interval. After the "overs" the athlete returns to the under wattage until the next "over."

Over unders are variable power workouts that have 2 benefits:

1. Specificity: they simulates the surges you encounter in races and group rides.
2. Indoor and smartTrainer** Friendly: Changing intensities helps the time pass more quickly on the trainer.

** we recommend ERG mode off for the transitions between low and high power

Over Under intervals replicate the power demands* of road, mountain, gravel, fondo and several other types of bike races. In this training tip, we’ll describe the how, what, where, and why of over under intervals and provide 3 example workouts plus a link to our Sweet Spot Part 3 training plan that includes over unders intervals.

The Physiological & Practical Benefits of Over Under Intervals

By alternating your power output just above and just below your lactate threshold, the “over” portions spike lactate production, while the “under” portions train your body to clear it efficiently—leading to five key physiological benefits:

1. Improved Lactate Clearance

   • By repeatedly flooding your system with lactate (“over”) and then stepping just below threshold (“under”), your body gets better at clearing lactate and maintaining higher intensities for longer.

2. Increased Muscle Buffering Capacity

   • The ability to buffer (or neutralize) acid buildup in the muscles is enhanced, allowing you to sustain efforts near threshold without excessive fatigue.

3. Enhanced Aerobic Endurance

   • Consistently working near your threshold strengthens your cardiovascular system, improves oxygen delivery to working muscles, and supports a higher Functional Threshold Power (FTP).

4. Race-Specific Adaptations

   • These intervals mimic the surges and recoveries experienced in real-world scenarios—like attacking on climbs or responding to accelerations in a group—making them highly relevant to competition.

5. Mental Toughness

   • Over-unders are challenging. Training your mind and body to embrace repeated surges while still recovering below threshold builds confidence and resilience for race day.

Example Workouts & 4 Week Progression

Below are four example Criss-Cross workouts. There are infinite combinations of overs and under lengths and intensities, so here are some simple over under workouts that don't break your brain with complexity. 

In this progression, each week, the intervals become more challenging—culminating in the “diabolical” Criss-Cross. There is even an example of what I give to World Tour level athletes.

1. Zone 6 > Tempo > Zone 6 (20 seconds): 2 sets of 2 x 3 min On 2 min Off with 20 sec "Overs"

This is a basic over under workout with the majority of the time spent at tempo wattages except for the beginning and the end 20 seconds anaerobic.

2. Sweet Spot Over Unders: 5 x 5 minutes

 This is an intermediate level over under workout because there's a minute of zone 6 combined with 4 minutes of sweet spot for each interval. There's 30 seconds of zone 6 work at the beginning and at the end that bookend 4 minutes of sweet spot work. The challenge is to not go TOO hard for the first over so that the sweet spot feels too hard and consequently the final over can be managed at 150% of FTP!

This intermediate level workout may be made advanced by increasing the sweet spot 'under' to threshold wattages or the length of the sweet spot 'under'.  Average power data analysis of the beginning to end of the whole interval will reveals a VO2 Max interval.

3. Threshold Over Unders: 3 x 12 minutes (1 minute Over/1 minute Under) *** Diabolical ***

This is the advanced level over under workout and honestly mimics zwift racing, gravel racing and even hard criteriums: surging at 110% of FTP or 'sitting in' at 90% of FTP.

In our Sweet Spot Part 3 training plan ,the FasCat Coaches include Over Under intervals once a week as athletes finish building their base fitness and training load. The brief “overs” bridge the gap from base training to more intense, full-gas intervals, as discussed in our recent Wintertime Intensity tip. Over Under intervals also offer three additional benefits:

• Generate a larger training load (OTS) compared to standard Sweet Spot or Tempo workouts
• Increase aerobic endurance while transitioning from base to high-intensity efforts
• Help break up the monotony of indoor training

For an added challenge, you can “enhance” Over Under workouts by extending the “over” segments from 20 seconds to 30 seconds, or even up to 1–2 minutes.

The most diabolical Over Under Interval workout we've ever prescribed is the following containing a 2 minute anaerobic over at 125% followed by a 30 sec 150% FTP effort to simulate the climbs at Liege Bastogne Liege and the Amstel Gold Race:

4. World Tour Over Unders: 4 x 5 (2 minute) minutes (1 minute Over/1 minute Under)

Want a Training Plan with Over Unders?

Check out our Sweet Spot Part 3: Base to Race plan:

• Transitions you from base to race with the above over under interval progression
• Increases aerobic fitness and power
• Perfect continuation from Sweet Spot Part 2

COPYRIGHT © 2025 FASCAT COACHING. ALL RIGHTS RESERVED.

FasCat gives you two ways to ride faster! 

Try CoachCat for free for one month, no credit card is required!

CoachCat is your AI-Powered Coach available 24/7/365.  Follow a custom training plan with unlimited revisions and instant analysis. The first month is free and no credit card is required!