Stiff-Legged Deadlifts vs Nordic Curl for Hamstring Growth?

Key Points:

Elite rugby players were assigned to train either the stiff-legged deadlift or Nordic hamstring curl twice weekly for five weeks.
Muscle fascicle length and muscle thickness in the biceps femoris tended to increase more in the Nordic curl group than in the stiff-legged deadlift group. Both groups increased eccentric hamstrings strength to a similar degree.
Short muscle fascicle length and low eccentric hamstrings strength are two risk factors for hamstrings strain injuries.

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Which exercise is the best for preventing hamstrings strain injuries? And which is the best for growing your hamstrings muscle size?

In this article, I’ll briefly review a new study on hamstrings training, performed on elite Brazilian rugby players.¹ I first discovered this study through the newsletter MASS, for which we are an affiliate.

Hamstrings strain injuries are common in many team sports, including rugby, with a prevalence of around 0.27 and 5.6 hamstrings strain injuries per 1000 h of exposure in training and matches, respectively. As each hamstrings strain injury leads to 17 days of lost time and the recurrence rate is high (23%), finding effective preventative training methods is valuable.

One such preventative method is the Nordic hamstring curl, which has been found to halve the risk of hamstrings strain injuries when it is included in the athletes’ training program.²

In this study, the researchers wanted to compare the results from training Nordic hamstring curls with doing stiff-legged deadlifts.

Participants and Method

The researchers managed to recruit a team of 23 Brazilian premier league rugby players with a mean rugby training experience of ten years. The players were split into two groups, which trained either the Nordic hamstrings exercise or stiff-legged deadlift, twice weekly, for five weeks.

The sets and reps increased throughout the five weeks, in this manner:

Week 1: 2 sets x 8 reps
Week 2: 3 sets x 8 reps
Week 3: 3 sets x 10 reps
Week 4: 4 sets x 10 reps
Week 5: 4 sets x 12 reps

The stiff-legged deadlift group began their training with 75% of their 1RM, and increased the weight used when they believed they could do more than one repetition extra when the set was finished. They performed both the concentric and eccentric part of the exercise, just like in normal training.

The Nordic hamstring group only performed the eccentric part of the exercise, and simply tried to slowly lower themselves for as long as possible towards the ground. Then they caught themselves with their hands and pushed themselves up again. Thus, this group was effectively training at a much higher percentage of their 1RM.

One week before and one week after the five weeks of training, the researchers made a series of tests on the participants:

Muscle thickness and muscle fascicle length at the biceps femoris (a hamstrings muscle) midpoint, measured via ultrasound.
Hamstrings eccentric and concentric strength, measured in a BioDex machine.
Counter-movement jump height.

Adherence was an impressive 100%, meaning that every participant completed every single workout.

Results

When the tests were redone after the five weeks of training the researchers found that:

Biceps femoris muscle fascicle length increased significantly more in the Nordic hamstrings group than in the stiff-legged deadlift group: 14% vs. 6%.
Biceps femoris muscle thickness tended to increase more in the Nordic hamstrings group than in the stiff-legged deadlift group: 8% vs. 4%.
The increase in eccentric hamstrings strength was pretty similar between groups: 9% vs 7% for the Nordic hamstrings group and the stiff-legged deadlift group, respectively.
The stiff-legged deadlift group saw slightly greater increases in counter-movement jump (5%) and concentric hamstrings strength (6%) than the Nordic hamstrings group, which only gained 1% and 2%, respectively.

Here are the results summarized:

	Nordic Hamstring Group	Stiff-Legged Deadlift Group
BF Muscle Fascicle Length	14%	6%
BF Muscle Thickness	8%	4%
Hamstrings Concentric Strength	2%	6%
Hamstrings Eccentric Strength	9%	7%
Counter-Movement Jump	1%	5%

Practical Implications & Take-Away

The results of this study hint that the Nordic hamstring exercise is more effective than the stiff-legged deadlift for increasing biceps femoris fascicle length, and maybe more effective for increasing biceps femoris muscle thickness and hamstrings eccentric strength. The stiff-legged deadlift, on the other hand, seems more effective for increasing hamstrings concentric strength and counter-movement jump height. At least when the exercises are performed in the way they were in this study: only eccentrics for the Nordic hamstrings group, but both concentric and eccentric movements for the stiff-legged deadlift group.

So which one should you do?

Injury Prevention. If your main priority is to prevent hamstrings strain injuries, I’d recommend going with the Nordic hamstrings curl, as it already has strong evidence of halving the risk for these injuries. This study verifies that the Nordic hamstrings curl is effective at increasing muscle fascicle length and eccentric hamstrings strength.
Muscle Growth. If building bigger hamstrings is your main priority, I’d recommend that you train both a hip extending exercise (like stiff-legged deadlifts) and a leg curl exercise (like Nordic hamstring curls). It is possible, even likely, that these movements will complement each other and lead to better total muscle growth.

Want to read much more about growing your hamstrings? Check out our hamstrings training guide!

More reading:

Stiff-Legged Deadlifts vs Nordic Curl for Hamstring Growth?

Participants and Method

Results

Practical Implications & Take-Away

References

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