Does Stretching Beat Lifting for Flexibility? A New Trial Says No

Quick answer: No. In a six-week randomised trial by Luangpon and colleagues, published 1 June 2026 in the Journal of Musculoskeletal and Neuronal Interactions, 68 men with tight hamstrings did an hour of daily stretching, four minutes of stretching three times a week, or a hamstring exercise three times a week. All three gained range of motion, and no group beat the others.

Somebody in your gym stretches for 40 minutes and swears it is the only reason they can touch their toes. Somebody else has not stretched since school and squats to the floor.

The tempting conclusion is that more stretching buys more flexibility, so an hour a day should buy a lot of it. A group of researchers in Thailand and Lithuania actually ran that experiment, with a single-leg Romanian deadlift as the comparison, and the answer is not the one the hour-a-day camp wants.

What the researchers actually did

Sixty-eight young men who could not raise a straight leg past 80 degrees were randomly split into four groups of 17. Everything happened at home, on the dominant leg only, for six weeks.

• Long-duration stretching. A supine hamstring stretch with a towel, held 60 seconds, repeated 60 times with 15-second rests. Every day. That is an hour of stretching per session, 42 sessions.
• Typical static stretching. The same stretch, six holds of 30 seconds, three times a week. 18 sessions.
• Hamstring resistance exercise. A single-leg "T-drop" Romanian deadlift, 6 sets of 30 reps with a two-second lowering phase, three times a week. 18 sessions.
• Control. General physical activity advice and nothing else.

Blinded assessors measured maximum passive knee extension range of motion on a dynamometer, passive stiffness of the hamstring, biceps femoris thickness by ultrasound, and knee flexor strength, at baseline, six weeks, and three months later. Nobody dropped out, and every prescribed session was completed.

What did they find?

Every group that did something improved. The one that did 23 times more work did not improve 23 times more.

An hour of daily stretching did not beat four minutes three times a week

0°5°10°15°

10.9°

5.6°

8.5°

Long-duration stretching

Typical static stretching

Hamstring resistance exercise

View the data

Group	Long-duration stretching	Typical static stretching	Hamstring resistance exercise
Range of motion gained over 6 weeks	10.9°	5.6°	8.5°

Read that carefully. The hour-a-day group did gain the most on average, 10.9 degrees against 5.6 and 8.5. But the study could not tell the three groups apart statistically, and the confidence interval on that 10.9 ran from 2.5 to 19.3 degrees, which is a very wide range for a supposedly decisive result.

The single-leg Romanian deadlift gained 8.5 degrees without a single stretch being held. A hamstring exercise done three times a week produced range of motion in the same territory as an hour of daily stretching, which is the part of this that should interest anyone who already lifts.

All three improvements were still there at the three-month follow-up.

The stretching groups changed the tissue. The lifting group did not.

Range of motion improved everywhere, but the reason differed.

Only stretching made the hamstring less stiff

• Before
• After 6 weeks

0 Nm/deg0.5 Nm/deg1 Nm/deg1.5 Nm/deg

1.05 Nm/deg

0.92 Nm/deg

0.95 Nm/deg

0.82 Nm/deg

Long-duration stretching

Typical static stretching

View the data

Group	Long-duration stretching	Typical static stretching
Before	1.05 Nm/deg	0.95 Nm/deg
After 6 weeks	0.92 Nm/deg	0.82 Nm/deg

Both stretching groups reduced passive stiffness by 0.13 Nm/deg, and in the long-duration group that reduction was still present three months later. The resistance exercise group gained range of motion with no measurable change in stiffness at all.

No group grew any hamstring muscle. Biceps femoris thickness did not move in any of the four groups, on either leg. Strength went up across every group including the control, which the authors read as people getting better at the test rather than getting stronger.

Why did lifting work without changing the tissue?

Because range of motion is partly a nervous system setting rather than a pure tissue property. The researchers attribute the resistance group's gains to increased stretch tolerance: the same tissue, the same stiffness, but a higher threshold before your body says stop.

Think of the limit as an alarm rather than a wall. Repeatedly loading the hamstring near its end range, which is exactly what the lowering phase of a Romanian deadlift does, teaches your nervous system that the position is safe. The alarm moves.

Stretching seems to work on both fronts. It raises tolerance and it makes the tissue itself more compliant, which is what the stiffness numbers show.

This is the authors' proposed explanation, not something the study directly measured. They measured stiffness and range of motion, and inferred tolerance from a change in one without a change in the other. It fits the data well, and it is still an inference.

There is a practical wrinkle in it. The authors note that keeping stiffness intact may be an advantage for power sports, where elastic recoil in the tendon matters. If that is true, lifting your way to range of motion is not a second-best route to the same place. It is a different outcome.

What this study doesn't prove

• These men were not lifters. Regular resistance or stretching training was an exclusion criterion, and everyone had tight hamstrings to begin with. Someone who already squats deep three times a week may have far less to gain from any of this.
• The lifting group never trained hard. The protocol targeted an RPE of 18 to 19 out of 20 in the final two weeks. Only two participants got there, the average was 14, and the average extra load added was 2.7kg. A properly loaded Romanian deadlift might do more, or might do less. This study cannot say.
• Nothing here says stretching is useless. All three groups beat the control group, and both stretching protocols changed the tissue in a way the exercise did not. The finding is that an hour a day was not worth the extra 400-odd minutes a week, not that four minutes is optimal.
• The stiffness and strength outcomes were exploratory. The sample size was calculated for range of motion only, so the study was not designed to detect differences in the other measures. Failing to find one is not the same as showing there is none.
• Everyone stopped. At the three-month follow-up the median number of continued sessions per week was zero, in every group. The gains persisted, but nobody kept the habit.
• It is 68 young men over six weeks. One trial, one demographic, one muscle group, all done at home. It shifts the odds, it does not settle anything.

The paper is open access under a Creative Commons licence, funded without any reported conflicts of interest, and registered in advance with the Thai Clinical Trials Registry.

What each protocol actually cost

Satisfaction tracked the time cost almost exactly. The four-minute group rated the program highest, at a median 3 out of 3. The hour-a-day group and the lifting group both rated it 2.

How to test this in your own training

1. Measure before you change anything. Lie on your back, raise one straight leg as far as it goes, and photograph it against a doorframe. That photo is your baseline.
2. Pick one route for six weeks. Either add a hamstring exercise with a slow lowering phase three times a week, or add four minutes of hamstring stretching three times a week. Not both, or you will not know which worked.
3. Log the exercise like any other lift. Sets, reps, load, and the tempo. A Romanian deadlift with a two-second lowering phase is a different exercise from one you drop.
4. Retake the photo at six weeks, from the same spot, and compare. Anything under about five degrees is inside the noise of a home measurement.
5. Then decide what it is worth. If lifting got you the range of motion you wanted, the stretching session was time you can spend elsewhere.

Six weeks of data beats any group average

The study reports what happened to 17 men per group on average. It cannot tell you whether your hamstrings respond to Romanian deadlifts or to stretching, and the confidence intervals in this paper are wide enough that individual variation is clearly large.

The only way to find out is to run one variable for six weeks and read your own numbers back.

If you type your sessions into your phone's notes app, you already have the raw material. Gym Note Plus turns those lines into a per-exercise history, so a six-week Romanian deadlift block becomes a chart instead of a scroll.

• Type the set in plain text, tempo notes included.
• See the trend per exercise, so you know whether the load actually progressed.
• Pull up last session in a tap, which is what keeps a six-week test honest.

Paste an old leg session into the free notes to workout translator and see what six weeks of your own data looks like.

An hour of daily stretching gained 10.9 degrees. Three Romanian deadlift sessions a week gained 8.5. The study could not tell them apart, and one of them fits into training you already do.

Frequently Asked Questions

What did the 2026 hamstring stretching study find?

The trial by Luangpon and colleagues, published 1 June 2026, randomised 68 men with tight hamstrings into an hour of daily stretching, four minutes of stretching three times a week, a hamstring resistance exercise three times a week, or a control group. All three exercise groups gained range of motion, and no group significantly outperformed the others.

Can resistance training replace stretching for flexibility?

For range of motion, this trial suggests it largely can. A single-leg Romanian deadlift performed three times a week gained 8.5 degrees of hamstring range of motion over six weeks, statistically indistinguishable from stretching. The difference is that only stretching reduced passive tissue stiffness, so the two are not producing identical adaptations.

Does more stretching produce more flexibility?

Not proportionally. This study compared roughly seven hours of stretching a week against under 15 minutes and found gains of 10.9 versus 5.6 degrees, a difference too small and too variable to call reliable. Stretching more than a few minutes per muscle group per week produces heavily diminishing returns.

Does stretching build muscle?

Not in this trial. Biceps femoris thickness did not change in any group, including the group stretching an hour a day for six weeks. Earlier calf research has reported growth from very high-intensity stretching, and the authors suggest their hamstring stretch simply was not intense enough to load the muscle that way.

How long do flexibility gains last after you stop?

In this study, range of motion gains were still present three months after the six-week program ended, even though the median participant did zero sessions per week during that follow-up. The reduction in tissue stiffness persisted only in the group that had stretched for an hour a day.

Final Takeaways

• An hour a day was not worth it. 10.9 degrees against 5.6 for a program taking 30 times longer, and the difference was not reliable.
• A hamstring exercise gained 8.5 degrees with no stretching at all, three sessions a week.
• Only stretching reduced tissue stiffness. Lifting raised range of motion by raising tolerance instead.
• Nothing grew. No group gained hamstring thickness, and strength gains looked like test practice.
• Test it on yourself for six weeks. Group averages with intervals this wide cannot tell you your own answer.