Kenny Croxdale
Level 7 Valued Member
For Maximal Strength Gains, Should You Use Slow Eccentrics?
For maximal strength gains, should you use slow eccentrics? - Bret Contreras
What is the force-velocity relationship?
The force-velocity relationship describes how the maximal force produced by muscles while they are shortening is inversely proportional to their contraction velocity.
In other words, producing very high levels of force limits muscles to shortening slowly, while shortening very quickly limits muscles to producing a much smaller amount of force, even though the effort exerted is maximal in both cases (Wickiewicz et al. 1984; Sale et al. 1987; Hortobágyi & Katch, 1990; Westing et al. 1990).
However, during lengthening (eccentric) contractions, the force-velocity relationship is the opposite way around (Hortobágyi & Katch, 1990; Westing et al. 1990). In fact, to produce high levels of force requires muscles to lengthen quickly, not lengthen slowly!
Here is a graph to show both of these relationships together:
It is less complicated than it seems!
By looking at the graph above, there are four cases:
Why lower under control during normal strength training?
So now that we understand the force-velocity relationship, we can start to understand why many strength coaches recommend lowering loads slowly under control in the eccentric (lengthening) phase of normal strength training.
The fact is, that you are very much stronger when you lower a weight (eccentrically) than when you lift a weight (concentrically), and the difference is around 30 – 50% (Duchateau & Enoka, 2015).
Andrew Serranno
So if we want to lift the same weight in both concentric and eccentric phases (as most people do, most of the time), then we need to manipulate the force-velocity relationships so that the eccentric is harder than it should be.
Lowering under control is one way of doing that.
Slow eccentrics require you work harder against what is basically a comparatively much lighter weight. This is why lowering slowly is often recommended during normal strength training, instead of lowering quickly.
If you lowered quickly after lifting, it would be far too easy.
Why go fast (and heavy) when doing eccentric-only training?
Some strength coaches also recommend eccentric-only workouts where the load is lowered very slowly. They recommend spending several seconds lowering the weight, and then getting a partner to help you lift it back up to the top.
Even though lowering slowly is a good idea when combined with a concentric phase, it is not the best way to get stronger in the context of eccentric-only training.
When using eccentric-only training, lowering slowly is less effective for gaining strength, because you force yourself to use lighter weights, simply so that you can lower them more slowly. If you lowered more quickly, you could use a much heavier weight (just don’t use a weight that is so heavy you can’t control it, and end up dropping it).
And even though the jury is out when it comes to lighter loads and hypertrophy (Schoenfeld et al. 2015), I think we can all agree that using heavier loads will almost always make you stronger, probably because they provide greater mechanical loading (Schoenfeld, 2010), and I would bet that this applies even when you are just doing eccentric-only training.
But is that what the research says?
Let’s take a look.
Does going fast in eccentric-only training produce greater strength gains?
The few studies that have been done comparing the effects of slow and fast eccentric-only training show similar results. Faster (i.e. heavier) eccentric-only training is indeed a much better training method than slower (i.e. lighter) eccentric-only training, if your goal is primarily to get stronger (Paddon-Jones et al. 2001; Farthing & Chilibeck, 2003a; 2003b; Shepstone et al. 2005).–
For example, Farthing & Chilibeck (2003a; 2003b) both assessed the strength gains in groups who did elbow flexion training on a dynamometer at either a fast velocity (180 degrees/s) or at a slow velocity (30 degrees/s), increasing volume progressively from 2 – 6 sets of 8 reps per workout over the first 13 training sessions, and then maintaining at 6 sets for training sessions 13–22 before a taper in the final 2 workouts. The fast group increased eccentric strength by more than the slow group, irrespective of whether the strength test was performed at the fast or slow speed.
Here are the results from Farthing & Chilibeck (2003b):
Slow eccentric-only training does not look that great!
Since Farthing & Chilibeck (2003a) also observed greater gains in muscle thickness (measured by ultrasound), they ascribed these greater gains in strength to larger amounts of hypertrophy caused by the higher mechanical loading. These findings are in line with those reported by Paddon-Jones et al. (2001), who found larger gains in type II fiber proportion after fast eccentric training, compared to slow eccentric training.
And doubtless hypertrophy did indeed play some role, although simply using the heavier loads almost certainly had other beneficial (both peripheral and central) effects on strength gains as well.
Later, Shepstone et al. (2005) confirmed these findings, as they found greater gains in strength (at both testing speeds) and muscle fiber size in a fast group, compared to a slow group. In addition, they reported greater muscle fiber damage or remodelling in the fast group. This type of remodelling seems to involve the cell cytoskeleton, including titin and related signaling proteins (Barash et al. 2004; Lehti et al. 2007; 2009). Given that titin is probably key for producing passive force while muscles are lengthening, and is almost certainly responsible for the unique behavior of eccentric contractions, this would be an exiting development.
Very recently, Sharifnezhad et al. (2014) compared two different long-term programs of eccentric training with different angular velocities but exactly the same force levels. The force used in both groups was 100% of maximum isometric force, while the angular velocities used in each group were 90 and 240 degrees/s, respectively. The slower angular velocity showed a tendency to superior strength gains, which is exactly in line with our expectations based on the force-velocity relationship.
The group who trained with the higher angular velocity could have easily used a much heavier load, so the relative loads (percentage of maximal force) in each group were very different.
And heavier loads produce greater strength gains.
For maximal strength gains, should you use slow eccentrics? - Bret Contreras
What is the force-velocity relationship?
The force-velocity relationship describes how the maximal force produced by muscles while they are shortening is inversely proportional to their contraction velocity.
In other words, producing very high levels of force limits muscles to shortening slowly, while shortening very quickly limits muscles to producing a much smaller amount of force, even though the effort exerted is maximal in both cases (Wickiewicz et al. 1984; Sale et al. 1987; Hortobágyi & Katch, 1990; Westing et al. 1990).
However, during lengthening (eccentric) contractions, the force-velocity relationship is the opposite way around (Hortobágyi & Katch, 1990; Westing et al. 1990). In fact, to produce high levels of force requires muscles to lengthen quickly, not lengthen slowly!
Here is a graph to show both of these relationships together:
It is less complicated than it seems!
By looking at the graph above, there are four cases:
- High force concentric = low velocity
- Low force concentric = high velocity
- High force eccentric = high velocity
- Low force eccentric = low velocity
Why lower under control during normal strength training?
So now that we understand the force-velocity relationship, we can start to understand why many strength coaches recommend lowering loads slowly under control in the eccentric (lengthening) phase of normal strength training.
The fact is, that you are very much stronger when you lower a weight (eccentrically) than when you lift a weight (concentrically), and the difference is around 30 – 50% (Duchateau & Enoka, 2015).
Andrew Serranno
So if we want to lift the same weight in both concentric and eccentric phases (as most people do, most of the time), then we need to manipulate the force-velocity relationships so that the eccentric is harder than it should be.
Lowering under control is one way of doing that.
Slow eccentrics require you work harder against what is basically a comparatively much lighter weight. This is why lowering slowly is often recommended during normal strength training, instead of lowering quickly.
If you lowered quickly after lifting, it would be far too easy.
Why go fast (and heavy) when doing eccentric-only training?
Some strength coaches also recommend eccentric-only workouts where the load is lowered very slowly. They recommend spending several seconds lowering the weight, and then getting a partner to help you lift it back up to the top.
Even though lowering slowly is a good idea when combined with a concentric phase, it is not the best way to get stronger in the context of eccentric-only training.
When using eccentric-only training, lowering slowly is less effective for gaining strength, because you force yourself to use lighter weights, simply so that you can lower them more slowly. If you lowered more quickly, you could use a much heavier weight (just don’t use a weight that is so heavy you can’t control it, and end up dropping it).
And even though the jury is out when it comes to lighter loads and hypertrophy (Schoenfeld et al. 2015), I think we can all agree that using heavier loads will almost always make you stronger, probably because they provide greater mechanical loading (Schoenfeld, 2010), and I would bet that this applies even when you are just doing eccentric-only training.
But is that what the research says?
Let’s take a look.
Does going fast in eccentric-only training produce greater strength gains?
The few studies that have been done comparing the effects of slow and fast eccentric-only training show similar results. Faster (i.e. heavier) eccentric-only training is indeed a much better training method than slower (i.e. lighter) eccentric-only training, if your goal is primarily to get stronger (Paddon-Jones et al. 2001; Farthing & Chilibeck, 2003a; 2003b; Shepstone et al. 2005).–
For example, Farthing & Chilibeck (2003a; 2003b) both assessed the strength gains in groups who did elbow flexion training on a dynamometer at either a fast velocity (180 degrees/s) or at a slow velocity (30 degrees/s), increasing volume progressively from 2 – 6 sets of 8 reps per workout over the first 13 training sessions, and then maintaining at 6 sets for training sessions 13–22 before a taper in the final 2 workouts. The fast group increased eccentric strength by more than the slow group, irrespective of whether the strength test was performed at the fast or slow speed.
Here are the results from Farthing & Chilibeck (2003b):
Slow eccentric-only training does not look that great!
Since Farthing & Chilibeck (2003a) also observed greater gains in muscle thickness (measured by ultrasound), they ascribed these greater gains in strength to larger amounts of hypertrophy caused by the higher mechanical loading. These findings are in line with those reported by Paddon-Jones et al. (2001), who found larger gains in type II fiber proportion after fast eccentric training, compared to slow eccentric training.
And doubtless hypertrophy did indeed play some role, although simply using the heavier loads almost certainly had other beneficial (both peripheral and central) effects on strength gains as well.
Later, Shepstone et al. (2005) confirmed these findings, as they found greater gains in strength (at both testing speeds) and muscle fiber size in a fast group, compared to a slow group. In addition, they reported greater muscle fiber damage or remodelling in the fast group. This type of remodelling seems to involve the cell cytoskeleton, including titin and related signaling proteins (Barash et al. 2004; Lehti et al. 2007; 2009). Given that titin is probably key for producing passive force while muscles are lengthening, and is almost certainly responsible for the unique behavior of eccentric contractions, this would be an exiting development.
Very recently, Sharifnezhad et al. (2014) compared two different long-term programs of eccentric training with different angular velocities but exactly the same force levels. The force used in both groups was 100% of maximum isometric force, while the angular velocities used in each group were 90 and 240 degrees/s, respectively. The slower angular velocity showed a tendency to superior strength gains, which is exactly in line with our expectations based on the force-velocity relationship.
The group who trained with the higher angular velocity could have easily used a much heavier load, so the relative loads (percentage of maximal force) in each group were very different.
And heavier loads produce greater strength gains.