Training Load Helps You Find the Balance Between Under and Overtraining—Here’s How to Measure It
Most wearables track this metric, but it goes beyond simply paying attention to stats.
When it comes to running these days, wearables have become a part of the “uniform.” If you sift through race photos, you’ll probably see both recreational and professional runners looking down at their smartwatches at the finish line rather than glancing up to smile at the camera.
While most smartwatches capture basic metrics such as activity duration, heart rate, pace, and time, not all can measure the physiological effect of workouts over time or what’s known as “training load.” But with the new Apple training load feature, watchOS 11 will join the ranks of Garmin, Coros, and Polar and start providing insights into this metric.
So, if you’re considering buying a smartwatch—or you just want to better track your training and your progress—let’s learn about what training load is and how it can help or hinder your running.
What is training load?
Researchers of a scientific review published in Sports Medicine in 2017 define training load as the stress an athlete experiences after completing physical activities over a certain duration, most often a week. Another way to think about it is how hard you are physically working over time.
Training load is comprised of both an internal and external load. Internal load refers to the physiological and psychological effects of exercise on the body such as heart rate and rate of perceived exertion during exercise. The higher the heart rate or the harder a workout feels, the greater the internal load. External load refers to quantification of the work completed, such as pace and distance.
Sara Manderscheid, RRCA-certified endurance run coach and founder of Elevate Your Running, describes training load as the amount of stress that flows through the body in a training session or training season. “Every day is going to be different,” she says, referring to both the physical and psychological workload an athlete feels with both easy and challenging workouts.
Ric Rojas, head coach of Ric Rojas Running and coach with RISE Running in Boulder, Colorado—and father of pro runner Nell Rojas—highlights that both volume and intensity play roles in understanding an athlete’s perceived exertion. And that perception of exertion helps him determine whether training load is too high or too low. “Language and body language are the most important indices [of training load] that I use on a day-to-day basis,” he explains.
How do wearables measure training load?
Metrics used to estimate training load tend to differ among brands. For example, Garmin uses heart rate to estimate excess post-exercise oxygen consumption (EPOC), the amount of oxygen your body uses to return to homeostasis—a rested, refueled, and recovered state after a workout.
In general, EPOC accumulation is higher for more intense workouts and lower for easy efforts. EPOC measurements over a seven-day period equal your training load for the week. So, the higher your EPOC measurements, the higher your weekly training load.
Both Coros and Polar use training impulse (TRIMP) to estimate training load. TRIMP uses heart rate and workout duration to estimate effort during a workout with higher heart rates presumably reflecting higher efforts and higher TRIMP. Unlike EPOC, TRIMP may not be as reliable in estimating training load for strength training sessions, because it relies on metrics acquired during a workout rather than after.
Unlike Garmin, Coros, and Polar, Apple’s watchOS 11 will not provide a numeric value for training load. Instead, training load will be derived from workout duration and effort scores based upon a rate of perceived exertion scale from 1 to 10 with 1 equating to easy effort and 10 meaning an all-out effort. These scores can be generated automatically for 17 different workout types using an algorithm that incorporates age, height, weight, and performance metrics like GPS data, heart rate, and elevation. Scores can also be self-reported for any workout, a feature that distinguishes watchOS 11 from the rest of the pack.
After 28 days, the watchOS 11 algorithm establishes a training load baseline, and uses it to compare your training load over a seven-day period. The goal is to keep your seven-day training load or estimation of effort close to your 28-day baseline.
Can I use training load to build my workouts?
You certainly can! Many wearables prompt users with recommended workouts to help maintain training within an optimal load. Visual cues and graphics can also help users identify when fitness and fatigue are not balanced, which is an issue because too much fatigue can lead to overtraining, whereas workouts that may not be as challenging may hinder the ability to improve fitness.
Rojas uses heart rate data, pace, perception, recovery, and overall distance in a workout to generate the next workout (or workouts) and avoid overtraining. “I have to keep you healthy,” he comments. “I maintain an optimal training level to allow you to work out again without missing any time.”
To ensure balance in both training and recovery, Rojas also prioritizes an athlete’s perception of their effort during a workout. He will have athletes repeat the same workout every four weeks and evaluate how they felt at the prescribed paces. If the workout feels easier with time, they are likely building fitness. This should also correlate with heart rate: As you become more fit, your heart rate will get lower at the same pace—proof that “the training is taking you to the next level,” he says.
Manderscheid also uses perception more than the numbers, stating that communication is one of the best tools coaches have. “I feel that the mind is such a huge piece to training as a whole,” she says. She also emphasizes that it’s a fine balance of ensuring you do enough to gain fitness but don’t go overboard and set yourself up for injury.
Following Rojas’s and Manderscheid’s advice, you can use training load to schedule your own workouts by paying attention to effort and/or heart rate throughout a workout and throughout your week as a whole. You want a majority of easy efforts (RPE around 5 or 6 and heart rate around 60 to 70 percent) and a few harder efforts, like tempos or interval runs, mixed into your weekly schedule.
Keep in mind, if your typical paces start to feel hard or spike your heart rate, it could be an indication to lower your training load by taking an extra rest day or swapping a tempo run for an easy run. And if your typical paces start to feel too easy, it could mean you can increase your training load by adding more miles, faster paces, or another day of easy running.
Are there any downsides to tracking training load?
Metrics based upon algorithms have their pitfalls and training load is no different. Heart rate is one of the primary determinants of training load so anything that affects your resting heart rate (stress, sleep, etc.) can also influence training load.
Apple’s training load is also dependent on an effort rating system comparing seven-day training load to a 28-day baseline. So, if you rate a tough workout as a very easy effort, your watch will assume you are training below your baseline training load, which may prompt you to increase your effort. If you continue to rate hard efforts as easy, you may set yourself up for insufficient recovery, overtraining, and injury (especially if the workouts weren’t truly easy).
On the flip side, if you rate easy workouts as feeling hard, your watch will suggest you are training above your baseline, prompting you to decrease effort. As a result, you may not see fitness gains, because without a sufficient physiologic stimulus, you’ll likely plateau or lose fitness.
Both Manderscheid and Rojas note that there is incredible potential for over and undertraining when following training load on wearables in isolation for your workouts and progress tracking.
Manderscheid says training load is “one piece of the puzzle,” noting that it is easy for athletes to get bogged down in the analytics of their watch. “Can we stop, pause, and listen to our bodies? If we can connect a little bit more to that mind-body side of things, we are going to be stronger athletes,” she says.
What if you don’t have a wearable? How can you track training load?
If you don’t have a wearable, you don’t need to run out and get one; most of these devices are not cheap. Perceived effort—similar to what the Apple Vitals app is using to generate training load—is a free, easy, and reliable way to determine whether your workout is too easy, too hard, or just right.
Remember: You want a mix of both easy days and hard days on your calendar, without tipping too far in one direction. Both Rojas and Manderschied advise running easy efforts most days and incorporating harder efforts or intensities twice a week as a general guideline.
Manderscheid suggests going a step further than just mentally noting efforts and writing down how you felt at a particular workout. “At the end of the week, take a look, how did you feel: Did you feel good, strong, or terrible? Monitor that. Play around with it and experiment,” she explains.
Numbers are just a part of the puzzle in terms of how you can progress. “Keep the long view in mind,” Rojas says. Patience and perception work together to generate resilient, recovered runners capable of stacking training cycles. You can certainly be one of them, as long as you listen to your body—not just your watch—when it comes to your workout efforts and not going too hard or too easy all the time.
posted Saturday July 6th
by Runner’s World