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Strong Support

causal

History

After twelve weeks of training with muscles stretched under load, healthy young men gained 19% more muscle volume and 9% more connective tissue area in the biceps femoris long head compared to those...

Pro

Against

Mechanism

Synthesis from 1 study

How it works

When the hamstring is stretched while contracting hard with the hip bent, the muscle and its tendon sheet get pulled strongly, causing the muscle to grow bigger and the tendon sheet to thicken. This does not happen as much when the hip is straight, because the muscle isn't stretched as far.

Most probable mechanism

In Simple Terms

When the hamstring muscle is stretched while it contracts under heavy load, the muscle fibers and their connecting tendon sheet experience strong pulling forces. This force triggers the muscle to add more contractile units and the tendon sheet to thicken, making both larger and stronger. Training with the hip bent ensures the muscle is stretched the most, which is why this method produces bigger changes than training with the hip straight.

Causal chain

Hip flexion during eccentric knee flexion elongates the biceps femoris long head across both the hip and knee joints, placing it under maximal passive and active stretch.

Verified by multiple studies

which leads to

Eccentric contraction under this elongated state generates high mechanical tension and strain on muscle fibers and the proximal aponeurosis.

Verified by multiple studies

which leads to

Mechanical tension activates intracellular signaling pathways that increase muscle protein synthesis and suppress protein breakdown, leading to addition of sarcomeres in series and radial growth.

Supported by evidence

which leads to

Mechanical strain on the aponeurosis stimulates fibroblasts to increase collagen synthesis and reorganize extracellular matrix, resulting in increased aponeurosis area and width.

Supported by evidence

which leads to

The combined increase in muscle fiber volume and aponeurosis size enhances force transmission capacity and reduces strain concentration within the muscle tissue.

Supported by evidence

Evidence from Studies

Supporting (1)

Community contributions welcome

Hamstrings Hypertrophy Is Specific to the Training Exercise: Nordic Hamstring versus Lengthened State Eccentric Training

Randomized Controlled Trial

Human

2024 Oct 1

Contradicting (0)

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

Hamstrings Hypertrophy Is Specific to the Training Exercise: Nordic Hamstring versus Lengthened State Eccentric Training

Score: 55

DOI: 10.1249/mss.0000000000003490

Science Topic

Does lengthened state eccentric training increase biceps femoris muscle volume more than Nordic hamstring training?

Supported

Eccentric Training

We analyzed the available evidence and found that lengthened state eccentric training may lead to greater increases in biceps femoris muscle volume compared to Nordic hamstring exercises. In one study involving healthy young men, twelve weeks of training with muscles stretched under load resulted in a 19% increase in muscle volume and a 9% increase in connective tissue area in the biceps femoris long head, while Nordic hamstring exercises produced smaller gains of 5% and 3% respectively [1]. This single assertion is the only evidence we’ve reviewed so far, and it supports the idea that training with the muscle in a lengthened position could be more effective for building tissue in this specific muscle. We don’t have additional studies to compare or confirm these numbers, so our current analysis is based on this one observation. The evidence we’ve reviewed leans toward lengthened state eccentric training producing larger changes in the biceps femoris, but we can’t say whether this applies to other populations, training durations, or different types of exercises. More research would be needed to understand how consistent this pattern is. For now, if you’re looking to target the biceps femoris with exercises that stretch the muscle under load, this type of training might offer a stronger stimulus based on what we’ve seen so far.

0 items of evidenceView full answer

Similar Assertions

Training the hamstring muscle with exercises that stretch it fully increases the size of its connective tissue structures more than exercises that do not stretch it as much.

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Lengthened state eccentric training increases the size of certain hamstring muscles that help extend the hip more than Nordic hamstring training, while Nordic hamstring training increases the size of other hamstring muscles that do not extend the hip more than lengthened state eccentric training.

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After twelve weeks of either lengthened state eccentric training or Nordic hamstring training, maximum eccentric knee flexion torque increases by about 17% and 11%, respectively, and the improvement is not significantly different between the two exercises.

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Performing Nordic hamstring exercises for three weeks leads to a 6% increase in the rate at which nerve signals activate the biceps femoris muscle, but this increase stops after nine weeks, suggesting that initial strength improvements are driven by nervous system changes that become less influential over time.

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When you lower weights slowly during strength training, your body might release more growth-friendly hormones and cause more tiny muscle tears—this could help your muscles grow bigger over time.

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