A Step-by-Step Guide to Improving Your Thresholds

Trail runner on single track with snow-capped mountains in the background

To effectively train for an endurance event, or coach an athlete who is competing in one, accurate physiological data is key to guiding and monitoring training performance and intensity. Aerobic threshold (AeT) and anaerobic threshold (AT) are arguably two of the most crucial physiological indicators for an athlete to improve. Knowing your thresholds allows you to create individualized workouts that effectively target performance improvement, as opposed to a cookie-cutter approach to training which may or may not work for you.

Improve Anaerobic Threshold: Tempo Workouts

The anaerobic threshold (AT) is the point during exercise when an athlete’s body requires unsustainable levels of anaerobic metabolism in order to fuel the work. When we are right at our AT, our RPE is around 7 out of 10, and we can't keep up a full conversation. This type of effort can be sustained for 20 minutes and up to 60+ minutes in well-trained athletes.

A tried and true way for athletes to improve their anaerobic threshold is with tempo workouts. A typical workout consists of a 5 to 10-minute warmup, followed by a continuous effort at or slightly above AT, and concluding with a 10-minute cooldown. For those new to tempo workouts, you can start with 10 minutes at your threshold pace. As you progress, you can slowly work your way up to 30 minutes or more.

Improve Aerobic Threshold: Long Slow Distance (LSD)

The aerobic threshold is the effort level when the use of fat as a fuel source has maxed out, and we begin to rely increasingly on anaerobic glycolysis rather than the oxidation of fats. At AeT we are at an RPE of 3 out of 10, and we can easily keep up a full conversation. This is an effort level we can sustain for a very long time.

Long slow distance (LSD) workouts are long in duration and low in intensity. Regardless of the sport, athletes and coaches can include LSD workouts in a training program to see an increase in the AeT. An LSD workout would last anywhere from 30 minutes to 2 hours, depending on the condition of the athlete and the sport requirements. The intensity would be at or just above the AeT. When an athlete is at this point he or she can talk but not sing. The athlete is warm and maybe sweating slightly but can maintain this pace for a long period of time. The main adaptation that occurs during LSD workouts is increased growth of the capillaries that enter our muscles and deliver oxygen to them, as well as becoming more efficient at burning fat as a fuel source.

Train Both Aerobic and Anaerobic

For endurance athletes, both the aerobic and anaerobic systems are necessary to improve performance. The aerobic energy system provides long-lasting energy because it burns predominantly fat stores and the anaerobic energy system produces energy more quickly and allows an athlete to sustain higher intensities. By appropriately adopting and sequencing workouts like tempo runs and long slow distance, throughout a training cycle, you will significantly improve your endurance performance.

Kristen Hench

Kristen Hench, Ph.D., is a certified coach through USAT, USAT Para, ACE, USAC, ASCA, ASFA Yoga certified, and is a RRCA certified race director. She has trained beginner through elite athletes helping many to reach podium finishes as well as meet their personal goals in triathlon, running, track, and swimming. Kristen coaches adaptive sports with the USAF AFW2 program as a cycling coach and also works with a variety of able-body and parasport athletes through TRIMotion3. She enjoys helping children and youth get healthy, learn new life-long skills, and build confidence. She has coached internationally and was selected to coach in the 2018 and 2020 Invictus games. Kristen has also directed numerous family races and competed in several triathlons herself, including the Ironman distance events. She placed in the top three for her age group in the inaugural year of the Mountaineer Half Ironman and was one of the top swimmers in the 2004 Lake Placid Ironman. Besides triathlons, Kristen also enjoys marathons (with a PR of 3:15), triathlon, swimming, and a multitude of boot camp activities.