Stretching can increase strength, but the effect is small and depends heavily on how long and how often you stretch. A large meta-analysis covering 36 studies found that regular static stretching produced a small but statistically significant improvement in maximal strength. The gains don’t come close to what you’d get from resistance training, and the practical takeaway depends on the type of stretching, the timing, and how much of it you do.
What the Evidence Actually Shows
A 2024 systematic review and meta-analysis in Sports Medicine pooled data from 36 studies and found that chronic static stretching programs increased maximal strength by a small but meaningful amount. The effect was more pronounced when people stretched for 15 minutes or more per session and continued their program for longer than six weeks. Shorter durations, under 15 minutes per session, didn’t reach statistical significance for strength gains.
Frequency matters too. Programs performed more than five times per week produced measurable increases in muscle size, while less frequent stretching did not. The same review found a small positive effect on muscle hypertrophy (actual muscle growth), though again, only when the volume and duration were high enough.
To put concrete numbers on it: in one six-week study where participants stretched their calf muscles for 60 minutes daily, maximal voluntary contraction improved by about 16% and one-rep max increased by roughly 25%. A group stretching for 120 minutes daily saw even larger gains, around 23% in maximal contraction. These are striking numbers, but they involved stretching durations that most people would find impractical, using calf muscle orthoses or stretching boards for an hour or more every day.
Why Stretching Can Build Muscle
The exact mechanisms aren’t fully understood, but the prevailing theory centers on mechanical tension. When you hold a muscle in a lengthened position for a long time, the sustained tension appears to stimulate some of the same growth signals that resistance training does. Animal studies have shown this clearly for decades. Translating those results to humans has been trickier, because animal models often involve continuous stretching for hours or days, something you can’t easily replicate in a gym.
The human studies that show the most consistent strength and size gains have tried to mimic that approach, using high stretching volumes of 7 to 14 hours per week. Studies using more typical stretching routines (four sets of 30 seconds, three days a week for eight weeks, for example) have produced inconsistent results. Some show small gains, others show nothing. The research so far is also almost entirely limited to the calf muscles, so it’s unclear whether these effects apply to larger muscle groups like the quads or chest.
Stretching Between Sets of Lifting
One practical application that’s gained attention is stretching a muscle between sets of resistance exercise. An eight-week study had trained men perform calf raises in two conditions: one leg rested passively between sets, while the other leg received a 20-second loaded stretch between each set. The stretch condition showed a modest advantage in both muscle thickness and isometric strength, particularly in the deeper soleus muscle. The effect wasn’t dramatic, but it came from just 20 seconds of stretching per rest period, making it one of the more time-efficient strategies.
If you already do resistance training and want to experiment, adding a brief stretch of the target muscle during your rest periods is a low-cost way to potentially squeeze out a small extra benefit.
Stretching Before a Workout Can Temporarily Reduce Force
There’s an important distinction between the long-term (chronic) effects of stretching and what happens immediately after you stretch. Holding a static stretch for more than 60 seconds per muscle group before exercise can temporarily reduce your ability to produce force. The impairment is real but modest, and it tends to last only a few minutes. Shorter static stretches of 60 seconds or less produce only trivial decreases in strength and power.
This is why most guidelines, including those from the American College of Sports Medicine, recommend dynamic stretching before exercise. Dynamic stretching involves controlled movements through your full range of motion (leg swings, arm circles, walking lunges) and doesn’t carry the same acute performance cost. When comparing dynamic and static stretching head to head before anaerobic exercise, dynamic stretching tends to produce slightly better power output, though the difference is small to moderate.
When to Stretch for the Best Results
The ACSM recommends static stretching at least two to three days per week, holding each stretch for 15 to 30 seconds and repeating two to four times, preceded by an active warm-up. For practical purposes, the best approach splits your stretching by timing:
- Before your workout: Focus on dynamic stretching and limit static stretches to short holds. This warms up your muscles without reducing force output.
- After your workout: This is the ideal time for longer static stretches, held for 30 to 60 seconds each. Your muscles and joints are warm, which lets you work on flexibility more effectively.
- Between sets: Brief stretches of the muscle you’re training (15 to 30 seconds) may offer a small additional stimulus for growth, based on early research.
How Stretching Compares to Resistance Training
Stretching is not a substitute for lifting weights if your goal is to get stronger. The strength gains from stretching are small in magnitude and require surprisingly high volumes to become consistent. Most people stretching for a few minutes a day won’t see measurable strength improvements. The effect sizes in the research are roughly one-third to one-half the size of what you’d expect from even a basic resistance training program.
That said, stretching still has value in a strength-focused program. Greater flexibility allows your joints to move through a fuller range of motion during exercises like squats and bench presses. Muscles generally produce more force when they operate closer to their optimal length, and training through a full range of motion is consistently linked to better strength and size gains than partial-range work. So while the stretching itself may not make you much stronger, the mobility it provides can help you train more effectively.
For people who can’t do traditional resistance training, whether due to injury, age, or other limitations, long-duration stretching programs could serve as a low-intensity alternative that provides at least some stimulus for maintaining muscle mass and strength. But for anyone who can lift weights, stretching works best as a complement to resistance training, not a replacement.