Why Time Under Tension Matters for Flexibility, Recovery, and Injury Resilience
There's a lot of confusion around stretching, flexibility, and soft tissue treatments. Questions like “How long should I stretch?”, “Does it prevent injury?”, and “Is it even worth doing?” continue to swirl around fitness, rehab, and performance circles. Let’s dig into what the research actually says—and more importantly, how to use that knowledge for real-world results.
Stretching Alone Isn’t Enough
Let’s make one thing clear: passive stretching or hands-on soft tissue treatment by themselves are not sufficient for long-term change. While they can offer short-term mobility gains, lasting improvements come when these are paired with loading strategies—specifically, force-based movements like isometric and eccentric training.
This is supported by research showing that both mechanical tension from resistance training and long-duration stretching can result in comparable gains in flexibility, muscle thickness, and strength. A 2023 study found long-term, high-volume static stretching (up to 1 hour per day) produced results similar to hypertrophy training in muscle growth and voluntary contraction, confirming the role of mechanical tension in driving these adaptations (Warneke et al., 2023).
Time Under Tension: The Key Variable
If your goal is to improve tissue quality—specifically, the white fibrous connective tissues like fascia, tendons, and other non-contractile elements—time under tension (TUT) is the critical metric. This isn’t guesswork; it’s backed by multiple systematic reviews and experimental studies.
A 2025 meta-analysis by Ingram et al. concluded that stretch durations of 2 minutes or more per muscle group are necessary to produce meaningful improvements in range of motion (ROM) (Ingram et al., 2025).
Similarly, Warneke et al. (2023) demonstrated that longer stretch durations led to significantly better flexibility outcomes, especially when total weekly stretching volume was high.
That’s why in our clinic, we advocate for accumulating 5–30 minutes of time under tension per session—not necessarily in one hold, but through a combination of manual therapy and active isometric holds spread throughout the treatment.
The Mechanism: Priming Connective Tissues
The goal isn’t just to get bendy—it’s to make your connective tissues more resilient. Long-duration stretching and manual contact techniques target the non-muscular components—fascia, nerve sheaths, and other passive structures.
For example, research by Hirata and Akagi (2024) showed that static stretching significantly reduced non-muscular tissue stiffness, particularly in older adults. This reduction correlated with improved joint flexibility, suggesting that fascial and neural adaptations play a substantial role in range of motion (Hirata & Akagi, 2024).
But here’s the kicker: If you don’t load that new range of motion, the benefits fade. That’s why after lengthening, you need to reinforce it with strength and control.
Stretch. Load. Repeat.
We use a simple framework:
👉 Stretch the tissue (passively or manually).
👉 Load the tissue (usually with isometrics or eccentrics).
👉 Reinforce the pattern (with strength and movement control).
This method:
Improves flexibility and tissue resilience.
Encourages the tissue to adapt to stress.
Builds usable movement capacity—not just more range, but stronger range.
How Often Should You Do This?
A lot more than you think. With rising rates of connective tissue injuries in athletes, it’s clear that the current approach isn’t enough. Based on research and clinical experience, we recommend:
3 sessions per day
4–6 hours apart
Each session including both stretching and tissue-specific loading
Yes, that’s a big increase from the standard “stretch after your workout” routine. But when broken into manageable segments and paired with active reinforcement, it becomes not just doable—but essential.
Does It Prevent Injuries? Not Directly—But It Helps
Let’s not oversell stretching. It doesn’t prevent injuries on its own. However, by improving tissue quality, range of motion, and force-distribution capacity, it creates a protective buffer.
Once combined with loading at length—especially isometric and eccentric movements—the tissues are better prepared for the motions and forces they’ll encounter in real life or sport. The body becomes more robust, adaptive, and injury-resistant over time.
Conclusion: Make Time Under Tension Work for You
The future of flexibility and injury mitigation isn’t about just holding a stretch or rolling on a foam roller. It’s about creating real, mechanical change in connective tissues—then backing that up with smart, load-based training.
The formula is simple but powerful:
Stretch consistently (2+ minutes per target muscle)
Load the range (especially through isometrics or eccentrics)
Repeat daily
Progress with intent
You don’t need to stretch for an hour a day like in some studies, but accumulating time under tension—5 to 30 minutes per session—can transform your mobility and durability.
Cited Research
Ingram LA, Tomkinson GR, d'Unienville NMA, et al. (2025). Optimising the Dose of Static Stretching to Improve Flexibility: A Systematic Review, Meta-analysis and Multivariate Meta-regression. Sports Med. 55(3):597–617. doi: 10.1007/s40279-024-02143-9.
Warneke K, Wirth K, Keiner M, Schiemann S. (2023). Improvements in Flexibility Depend on Stretching Duration. Int J Exerc Sci. 16(4):83–94. PMID: 37113511.
Warneke K, Wirth K, Keiner M, et al. (2023). Comparison of the Effects of Long-Lasting Static Stretching and Hypertrophy Training on Maximal Strength, Muscle Thickness and Flexibility in the Plantar Flexors. Eur J Appl Physiol. 123(8):1773–1787. doi: 10.1007/s00421-023-05184-6.
Hirata K, Akagi R. (2024). Acute Effect of Static Stretching on Non-Muscular Tissue Stiffness and Joint Flexibility: A Comparative Study Between Older and Young Men. Eur J Appl Physiol. 124(3):793–803. doi: 10.1007/s00421-023-05307-z.
