On January 27th, 2023, Joe Klecker ran 12:54.99 in the 5,000m (4:09/mi) at the Boston University Terrier Invite. His performance ranked him as the 4th fastest American ever and 7th fastest in the world on an indoor track. Although Klecker is no stranger to fast times on the track, having made an Olympic Team in 2021 in the 10,000m, the 5k at BU was a major breakthrough and the first time he had dipped under the 13-minute mark. 

“Going into the race, the goal was to break 13. But going five seconds or more under was a little bit unexpected,” he said.

Cultivating a world-class performance like this doesn’t happen overnight. For Klecker, a 9x All-American at the University of Colorado and professional runner for On Running, achieving an all-time mark was about consistency, monitoring recovery, and avoiding training overtraining mistakes from the past.

Building Base Fitness 

COROS Education: Base Fitness measures your body’s ability to take on exertion from long-term training. The higher your Base Fitness, the more intensity your body can take. As your body adapts to harder efforts, your Base Fitness will increase. Base Fitness in the COROS app is calculated over a 6-week period, and measures the average Training Load during this time. Base fitness will gradually decline if you stop training for a while. 

With any running training cycle, you need to build a good mileage base and gradually increase training loads, allowing your body to adapt to harder, more intense efforts over time. For Klecker, the fall of 2022 was all about building that base, averaging about 110 miles per week to develop the aerobic system. 

Within Klecker’s COROS data, you can see a steady increase in Load Impact from September through November. In December, he actually dialed back his mileage by about 70%, which was a strategic decision made by coach Dathan Ritzenhein. The darker blue line indicates Klecker’s Base Fitness, which increases over time. The lighter blue line indicates Load Impact, which was steadily increasing in the fall, then reduced in December.

“I got injured Christmas break in 2021, and we wanted to avoid that this year. I was training really, really hard and I never really felt like I adjusted to the training load that much. And then eventually I got injured,” Joe explains. “You know, your schedule’s just not the same, there’s so many more variables.”

Increasing Load Impact

COROS Education: Load impact measures the amount of exertion you put your body through from short-term training. In the COROS app, it is calculated based on the total Training Load in the last 14 days with an exponentially weighted model. The higher your Load Impact, the more recovery your body will need. Load impact goes down if you take more rest.

After the 2022 Christmas break, it was time to ramp up intensity and volume before the indoor racing season began. There’s a very clear 4-week period where you can see Joe’s base fitness steadily increasing and spikes in his load impact, highlighting heavy workout efforts.

During this time, Klecker cites longer track workouts with more reps and faster threshold workouts at altitude in Boulder. He also slept in an altitude tent at 11,000 feet. The goal was to build fitness that would carry over through February when Klecker raced at the 2023 Annual Millrose Games in New York City.

Monitoring Fatigue and Recovery with COROS

COROS Education: Fatigue measures the difference between your Base Fitness and Load Impact on a 0-100 scale. It reflects the amount of fatigue your body is enduring recent training, while considering your ability to sustain harder workouts. A low Fatigue number indicates your body is recovered and prepared to take on harder efforts. A higher Fatigue number indicates your body needs rest to adapt to training. If your Fatigue is elevated for an extended period of time without proper rest, you may risk injury and overtraining.

Although Klecker was increasing volume and intensity in January, his COROS data shows that he was recovering very well, allowing him to increase Base Fitness and push harder during workouts. 

“In January the workouts were very intense, but I’d show up to practice the next day and actually feel relatively recovered. So that just let me know that my body was really adapting to the workouts, and I wasn’t overtraining to hit the workouts,” says Joe.

The 5 Different Fatigue Zones in the COROS App:

• Minimal (0-19): Your current training load is light and may reduce your fitness in the long term.
• Performance (20-39): Your current training load has been reduced to allow for optimal performance in races.
• Optimized (40-59): Your current training load is ideal for maintaining or improving your fitness.
• High (60-79): Your current training may be unproductive due to the high recent load.
• Excessive (80-100): Your current training load is excessive and increases the risk of injury.

Monitoring sleep with his COROS PACE 2 was also a huge benefit for Joe. “One of the main features I use with COROS to track recovery are the sleep statistics. It shows the REM sleep and deep sleep and that usually tracks with how I feel. So that was one thing in January that I really tried to pay attention to every day to make sure there weren’t too many days in a row where my sleep quality was pretty poor.”

“When I’d get up in the morning, I’d look at the sleep quality and make sure that it was good. Seeing that data would give me some confidence to know like, okay, I can keep training hard and I don’t need to let up because a lot of our long runs and workouts are based on how you feel,” he explained. His resting heart rate is typically 36-38 bpm when he sleeps.

Klecker’s Taper and Peak for Race Day

Following Klecker’s 4-week build, you see a sharp decline in Load Impact (the light blue line) leading up to race day on January 27th. This intentional taper allowed him to time his recovery and plan for peak performance. As mentioned earlier, his Fatigue level was 35 (on a scale of 0-100), which was ideal for peak performance.

“Being able to break 13 was largely due to that 4-week block in January where everything was coming very naturally. It wasn’t one specific workout, for me it was consistent training and recovery.”

What’s Next for Joe Klecker

Klecker continues to train with the On Athletics Club in Boulder, CO. Coached by 3x Olympian Dathan Ritzenhein, Klecker has his sights set on big goals. Under coach “Ritz”, the OAC team has already broken multiple American records, including the men’s mile, women’s 3000m, and women’s 10,000m. With Paris 2024 just around the corner, Klecker is in perfect position to run even more fast times and represent Team USA.

If you want to stay up to date with Klecker’s training, give him a follow on Strava and Instagram. To learn more about COROS metrics, including Base Fitness, Training Load, and Fatigue, check out our blog!