Eccentric Training and GymAware: Keys to Quantifying Metrics that Matter

We all know the highly effective adaptations from eccentric training, but in practice, most coaches and athletes only measure and prescribe training on concentric metrics like 1RM. According to a scientific survey, only 42% of practitioners monitor eccentric load, and only 25% use eccentric-specific testing.¹

Nowadays, you can easily measure eccentric training and performance metrics with a velocity-based training device like GymAware RS and GymAware FLEX. Here’s why this is useful when prescribing training and monitoring performance.

Why Quantifying Eccentric Movements Is Important

Not all eccentric movements are the same, and each has its unique benefits.² If you’re chasing after a certain benefit, like hypertrophy, it’s important to accurately prescribe the eccentric exercise. Eccentric load, eccentric velocity, and eccentric time under tension are three important ingredients that determine your training adaptation.

Not all eccentric movements are the same, and each has its unique benefits. If you’re chasing after a certain benefit, it’s important to accurately prescribe the eccentric exercise, says @loekvossen. Share on X

If you want to measure your eccentric performance and track progress over time, it becomes even more important to have objective data. Here’s a list of eccentric metrics, provided by GymAware, that can help prescribe eccentric training and track eccentric performance over time:

• Eccentric peak and mean force and power
• Eccentric peak and mean velocity
• Eccentric time under tension
• Eccentric dip and bar path

Quantify Eccentric Load and Eccentric Force

The most straightforward way to quantify your eccentric load is by looking at the weight. Although this could work for a single individual, it’s impossible to create a systematic training approach based on weight simply because the difficulty of lowering 80 kilograms is not the same for me and you. In fact, even within an individual, weight alone doesn’t describe how challenging the exercise is.

During concentric movements, coaches try to solve this by creating training programs based on %1RM. This allows them to put weight into perspective. Eccentric movements don’t have such a one-repetition maximum because, per definition, you’re lowering the weight, no matter what the load is. For some, the lack of an eccentric 1RM is a reason to use the concentric 1RM to determine eccentric load. However, that would contradict the goal of this article: to quantify eccentric training with eccentric metrics.

It’s not just a matter of principle. Using the concentric 1RM to determine eccentric load is also not ideal since it assumes a fixed relationship between concentric and eccentric muscle performance. In more practical terms, it assumes that doing five eccentric reps at 120% of the concentric 1RM is the same difficulty for me as it is for you. If we have a different force-velocity profile, this may not be the case. Moreover, this method of using 1RM also implies that there are no significant day-to-day differences in 1RM that would otherwise affect the load.

Using the concentric 1RM to determine eccentric load is not ideal since it assumes a fixed relationship between concentric and eccentric muscle performance, says @loekvossen. Share on X

One eccentric metric that does allow you to quantify eccentric load is the eccentric movement velocity. Suppose you are lowering a weight that is so heavy you cannot lift it or hold it in place isometrically. For these kinds of eccentric movements, the higher the load, the faster you drop it—assuming you are always doing your best to slow down the process of lowering the weight.

This phenomenon is represented in the force-velocity curve. Note that for concentric movements, it’s the other way around: the higher the load, the lower the velocity.

If you and I have the same eccentric velocity in the above-described eccentric movement, you could say we train at the same relative load in the force-velocity curve. You can now use velocity zones to target a specific area of the force-velocity curve, similar to (though not exactly the same as) concentric velocity zones.

Moreover, measuring eccentric velocity instead of using concentric 1RM also solves the issue of daily variance. On a bad day, you’ll be using less weight to train at the same eccentric velocity. This works like an autoregulated system: the better you feel, the more weight plates you’ll be putting on your barbell to match the velocity target.

This way of training is called velocity-based training (VBT) and it requires a VBT device that measures not only the concentric but also the eccentric velocity of your movement, in real time. The GymAware RS and GymAware FLEX do exactly that.

When you combine one of these hardware devices with the additional GymAware Cloud software, you can go beyond mean and peak eccentric velocity with metrics like mean and peak eccentric force and power. I’ll talk about these metrics in a bit when we look more closely at quantifying eccentric performance progress.

But first…

Should You Use High Loads or Low Loads?

Now that we can quantify eccentric loads, should you be aiming for high or low loads?

Before we can answer this, we need to define “high” and “low.” In scientific literature, a high load is considered a load that you cannot lift concentrically. High loads will force you to lower the barbell. The eccentric force that you apply during those high-load movements is larger than the maximal concentric force. Several terms are related to this type of training:

• Eccentric overload
• Supramaximal eccentric loading
• Heavy negatives
• Accentuated eccentric loading

According to scientific research, high-load eccentric exercises induce greater increases in eccentric strength than low loads.² Even within these supramaximal loads (>1RM), greater increases in hypertrophy are found with heavier loads. Additionally, heavy eccentric training induces both qualitative and quantitative changes in the tendon, with heavier supramaximal loads increasing tendon force and stress more.²

In practice, this means that as long as you do your best to slow down the process of lowering the weight, high bar velocities (as a result of higher loads, explained earlier) result in superior training adaptations. However, to limit soreness, it is advised not to aim for eccentric durations shorter than two seconds.

There is one practical challenge with these supramaximal loads: how to lower an object that you cannot lift. You can use a spotter (or two), to help lift the weight in the concentric phase. Weight releasers can do the job too. Just like the two-movement technique, lift the weight via a compound exercise, and lower the weight with an isolated exercise (or lift a weight with two legs and lower it with one). I’m sure that coaches who read this are experienced enough to know which technique suits their athletes best.

Quantify Eccentric Velocity and Time Under Tension

We already talked about using eccentric velocity to quantify eccentric load during supramaximal exercises (>1RM). In these exercises, the velocity is a result rather than a choice, given that you do your best to slow down the process of lowering the weight.

Eccentric velocity itself—regardless of whether applied in submaximal or supramaximal loads—is an important metric to look for, says @loekvossen. Share on X

However, eccentric velocity itself—regardless of whether applied in submaximal or supramaximal loads—is an important metric to look at. For instance: a very slow supramaximal eccentric movement using isokinetic dynamometry results in different muscle adaptations compared to a fast supramaximal eccentric movement.

Additionally, a deliberately slow-paced submaximal eccentric movement, with the aim of extending the eccentric time under tension, is different from a deliberately accelerated supramaximal eccentric movement to decrease the eccentric force.

Both previously mentioned VBT devices (GymAware RS and GymAware FLEX) display real-time mean and peak velocity and eccentric time under tension. If you want to do slow eccentric movements, you can set an eccentric countdown timer that automatically starts when you begin the eccentric phase of your movement.

Should Eccentric Training Be Fast or Slow?

Based on scientific studies, increases in eccentric strength become more pronounced when the testing velocity corresponds to the eccentric velocity used in training.² Additionally, fast eccentric training is superior to slow eccentric training when it comes to improving:

• Eccentric and concentric strength and power.
• Vertical jump, drop jump, stretch-shortening cycle efficiency, and sprinting performance.
• Fast-twitch fibers hypertrophy (cross-sectional area) and IIx fiber composition.

This indicates that slow-tempo (low load) eccentric movements to increase the eccentric time under tension are probably not the most effective.

Obviously, the eccentric movement velocity correlates with the eccentric time under tension of a single repetition. This scientific publication that talks about incorporating eccentric training found that you can expect an eccentric duration of 8–10 seconds at 110%–120% of concentric 1RM.³ At higher loads (125%–130% of concentric 1RM), the eccentric duration drops to around 4–5 seconds.³ Another publication mentions that an even shorter eccentric duration of 2–3 seconds is ideal for maximizing hypertrophy but advises not to go any lower, to limit soreness.⁴

Quantifying Flywheel Training: The Ideal Fast Eccentric Training?

A combination of high-load and high-velocity eccentric movements results in high muscle (motor unit) tension and high exercise-induced muscle damage. This is thought to be why a combination of high-load, high-velocity results in a higher hypertrophic response.²

Flywheel inertial training (FIT) is a scientifically proven example of how you can easily train eccentrically with high velocities, says @loekvossen. Share on X

Flywheel inertial training (FIT) is a scientifically proven example of how you can easily train eccentrically with high velocities. The eccentric load depends on the size of the flywheel + the energy you put in the flywheel (inertia) during the concentric phase and your eccentric deceleration strategy.

Video 1. Flywheel training explained (source and full article: Create eccentric overload in flywheel training)

The challenge with flywheel training is that it’s difficult to quantify the load due to the combination of several factors determining the eccentric load, mentioned above. With the new app update of GymAware, you can start quantifying the load of flywheel training by measuring the concentric and eccentric velocities. Recent research shows that the mean velocity of a flywheel exercise is a valid method to quantify load and individualize the prescription of flywheel training.⁵ You can attach the VBT device to the flywheel handle or harness. You can also use the GymAware jump strap to measure core velocity or attach the VBT device to an additional barbell/PVC pipe.

By looking at the eccentric dip—available in both the GymAware iPad app and the FLEX Stronger app—you can also control the eccentric technique during flywheel training.

Quantify Eccentric Performance Progress

So far, we’ve talked about quantifying eccentric movements and implementing these numbers into training. How about tracking eccentric performance over time? “You can’t improve what you can’t measure!”

There are several ways you can use eccentric metrics to track progress over time. Some examples of progress that you can measure using GymAware:

• Increased peak or mean eccentric force (N)
• Increased eccentric peak power (W)
• Increased eccentric rep duration at a given supramaximal weight (s)
• Decreased peak or mean velocity at a given supramaximal weight (m/s)

You can also look at changes in the force-velocity curve, for instance, by comparing your maximal eccentric force with your maximal concentric force. Literature shows that the eccentric strength is approximately 20%–50% greater than the concentric strength, but where do you fit in this range?⁴ The GymAware Cloud software allows you to track all these changes over time within and between individuals.

BONUS: Quantify Eccentric Movement Technique

Eccentric training is the shortest route to muscle damage and delayed pain (DOMS) if you don’t take the time to slowly progress the intensity over the course of a training program.¹ The best way to safely incorporate eccentric training into your program is by measuring and controlling the eccentric load, with all the eccentric metrics mentioned earlier.

On top of that, you can prevent injuries by maintaining a good technique when eccentric loads and velocities are high. I already mentioned that GymAware measures the eccentric drop, for instance in a squat. Additionally, the real-time bar path visualization ensures you maintain a proper technique.

Wrap Up

I hope this article has inspired you to consider using data to quantify your most effective training: eccentric training. If so, don’t forget to start by measuring your current eccentric performance so you can track it over time using the metrics provided.

If you’re new to these metrics, I recommend learning more about velocity-based training (VBT) in general via my PDF download.

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References

1. McNeill C, Beaven CM, McMaster DT, and Gill N. “Survey of Eccentric-Based Strength and Conditioning Practices in Sport.” Journal of Strength and Conditioning Research. 2020;34(10):2769–2775.

2. Douglas J, Pearson S, Ross A, and McGuigan M. “Chronic Adaptations to Eccentric Training: A Systematic Review.” Sports Medicine. 2017;47(5):917–941.

3. Mike J, Kerksick CM, and Kravitz L. “How to Incorporate Eccentric Training into a Resistance Training Program.” Strength and Conditioning Journal. 2015;37:5–17. 10.1519/SSC.0000000000000114.

4. Schoenfeld B. “The Use of Specialized Training Techniques to Maximize Muscle Hypertrophy.” Strength and Conditioning Journal. 2011 Aug;33(4):60–65. doi: 10.1519/SSC.0b013e3182221ec2

5. Martín-Rivera F, Beato M, Alepuz-Moner V, and Maroto-Izquierdo S. “Use of concentric linear velocity to monitor flywheel exercise load.” Frontiers in Physiology. 2022 Aug;13, 961572.