Time Under Load: A Spectrum, Not a Limit

How long should we hold a pose?

By Bernie Clark
May 1, 2026

 

It seems that every five to ten years, an old chestnut rises up again in the yoga community: the claim that the use of time in yin yoga is unwarranted, unhelpful, or even dangerous. Recently, the question returned—how long should we hold a stretch? Rather than answering that question directly, it is more useful to step back and consider a broader one: how do our tissues respond to stress or load in the first place?

Our tissues do not respond to a single variable such as time alone. They respond to a combination of factors—what kind of stress is applied, how intense it is, how long it is held, how often it is repeated, and the condition of the tissue itself. This was noted in a 2025 Delphi consensus statement that concluded stretching effects depend on multiple variables, including duration, intensity, and frequency.1 Different outcomes emerge at different time scales: short durations may improve range of motion, while reductions in stiffness often require several minutes, and longer-term structural adaptations require repeated exposures over weeks.

 

Figure 1: The Five Types of Physical Stress—call it “load” if you prefer (from Your Body, Your Yoga by Bernie Clark)

The Variables of Stress

There are several characteristics of the physical stress we put upon our tissues:

• Type: compression, tension, shear, torsion (twist), bending (see figure 1)
• Intensity: low to high
• Duration: seconds to hours or longer
• Frequency: how often the stress is applied and released
• Loading rate: slow or fast
• Tissue state: hydration, age, injury, etc.
• Recovery: time between exposures

The key for each variable, as for any medicine, is the dosage. This is true regardless of whether the tissue we are targeting is bone, cartilage, muscle, or fascia.

What is the Intention?

I am not going to attempt to define a black or white answer to what is the optimal time to hold a pose. Instead, I want to explore how different tissues respond to different durations and types of loading. 

What is our goal? What are we trying to accomplish by placing a load on our tissues? Not clearly understanding our intention can lead to confusion. Do we want to improve strength, stability, coordination, flexibility, mobility, or overall health and functionality? For example: one recent critique I heard of yin yoga is that it “down-regulates our nervous system” and “reduces neural drive”.² While this may be true, it applies primarily in the short term. Stretching for 60 seconds or longer can temporarily reduce our reflexes and strength.³ For example, imagine you are about to play tennis in a club tournament. It is not a great idea to stretch a lot. Doing an hour-long yin yoga practice before the match will reduce your performance. But this does not mean that a yin yoga practice has no value.

This is similar to getting advice to not spend an hour lifting heavy weights or going for a 10K run before playing your match. If you do that, your muscles will be tired and your strength reduced, in the short term, preventing you from performing your best on the court. But, this does not mean you should never lift weights or go for a run! Just do not do them before an important sporting event. The point is—just because there is some short-term loss of function from a yin yoga practice does not mean it is harmful in the long run. Tissues adapt

Time Under Load

 

Figure 2: Spectrum of Tissue Responses (illustration by ChatGPT)

 

Tissues respond to a spectrum of loading conditions. Time under load contributes to different responses depending upon frequency, intensity, and recovery.⁴ A brief, high-intensity load produces one kind of adaptation; a longer, lower-intensity load produces another. Neither is inherently superior. They simply operate through different mechanisms. Figure 2 and table 1 illustrate how different tissues optimally adapt to particular combinations of loading variables.

 

Table 1: Summary of Tissue Responses to Different Loading Conditions

The idea that tissues respond differently across time scales is not new. It has long been recognized in fields such as materials science, biomechanics, and mechanobiology, where concepts like creep, stress relaxation, and time-dependent cellular signaling are routinely studied. What is less often emphasized is how these principles apply to everyday movement and practices such as yoga.

At one end of the spectrum are very short, high-force events: jumping, sprinting, lifting. These loads are measured in milliseconds to seconds, but the forces are high and the rate of loading is rapid. This kind of stimulus is particularly effective for bone, tendon stiffness, and neuromuscular coordination. The tissue is being challenged by how much force it must tolerate and how quickly it must respond

Move slightly along the duration spectrum and we encounter short-duration holds, on the order of 10 to 60 seconds. These are common in conventional stretching protocols and regular hatha yoga classes. At this level, we begin to see the early phases of viscoelastic behavior: initial creep, early stress relaxation, and neural adaptations such as increased stretch tolerance.⁵ Much of the literature that argues against longer holds is focused here, because for the narrow intention of quickly increasing range of motion, these shorter exposures are often sufficient. But that does not mean longer durations have no value.

As duration increases into the range of one to several minutes, different processes begin to dominate. Viscoelastic deformation continues, but now fluid movement within the tissue becomes more relevant.⁶ The extracellular matrix is not static; it is a hydrated environment where water and molecules such as hyaluronan shift and reorganize over time. At the same time, fibroblasts (the cells that create a lot of our fascial tissues) begin to respond more fully. Their cellular skeleton (called the cytoskeleton) reorganizes, signaling pathways are activated, and biochemical messengers are released. These are not instantaneous events. They unfold over minutes, which is why the duration of loading becomes increasingly meaningful in this time range.

As we move into longer durations, minutes to hours, we enter the territory of posture, traction, and therapeutic positioning. Here, the load is often low, but the exposure is prolonged. The effects are cumulative. Tissues adapt gradually, fluid dynamics shift, and patterns of tension are reinforced or altered. This is the domain in which everyday life operates: sitting, standing, sleeping. It is also where many therapeutic interventions, such as splints or orthotics, exert their influence. The body is not responding to a peak force, but to the persistence of that force over time.

At the far end of the spectrum are very long durations, measured in hours to days. Wearing a cast and immobilization both fall into this category. Here, the effects become structural. Collagen, which forms the main fibers of our fascia, is reorganized; tissues may shorten or lengthen; and the watery extracellular matrix found outside of our cells can become more or less compliant (more elastic or stiffer) depending on the conditions.

Rehabilitation medicine provides a useful example of long-duration loading. Static progressive stretch (SPS) devices apply low-load stress at end range for extended periods, often 20–30 minutes, repeated daily over weeks.⁷ These protocols are based on creep and stress relaxation and have been shown to improve range of motion and restore function in patients recovering from injury or surgery. While applied to pathological tissues, they demonstrate a key point: sustained mechanical loading is biologically active and clinically effective when used appropriately.⁸

All these changes are powerful, but they come with risks. Each of these factors can be overdone. Too much short-term, high-frequency stress can lead to degeneration and breakage. Too much time under load without variation can lead to stiffness, reduced hydration, and, again, degeneration or wearing out. Stress duration at any point along the spectrum is not inherently beneficial or dangerous; it is simply a variable that must be used appropriately.

 

Summary of Tissue Responses · Bone responds best to brief, dynamic loading where force and rate matter more than duration. · Cartilage depends on cyclical loading and unloading to maintain fluid exchange. · Muscle adapts to both short, intense loading for strength and longer, lower-intensity stretching for flexibility, with neural factors dominating early changes. · Connective tissues, including fascia, respond across a broader spectrum, where time-dependent processes such as fluid movement and cellular signaling become increasingly relevant.

Benefits of Long Duration Load

The work of Helene Langevin and her colleagues is suggestive of the benefits of long duration stress and provide insight into how sustained mechanical loading may influence connective tissue. In a series of studies, they examined the effects of gentle, prolonged stretching on connective tissue. In one model of inflammation, mice subjected to daily stretching for about 10 minutes showed a reduction in tissue thickness, pain and inflammatory cell infiltration while increasing ease of movement compared to controls.⁹ In a later study involving tumor growth, similar stretching protocols were associated with slower tumor progression.¹⁰ While we must be cautious in extrapolating directly from mice to humans, these studies demonstrate a consistent principle observed in these models: long duration, low-intensity mechanical stress can influence the biological environment of connective tissue, including inflammation and immune activity.

How does this work? Langevin’s team discovered that fibroblasts exposed to sustained stretch do not respond immediately. Instead, over several minutes, they reorganize their cytoskeleton, change their shape, and release signaling molecules such as ATP into the surrounding extracellular matrix.¹¹ These responses unfold over time, suggesting that connective tissues, through their resident cells, respond to a sustained mechanical stimulus by initiating meaningful biochemical and structural changes. Langevin’s research into acupuncture, where the stimulus is continuously applied for 20 to 40 minutes, provides another example where similar time-dependent cellular responses can occur.¹²

In related studies, repeated, daily, long-duration stretching has been shown to reduce inflammatory cell infiltration, improve movement patterns, and decrease mechanical sensitivity, at least in rats.¹³ In addition, sustained stretch appears to influence the balance between tissue breakdown and repair by influencing fibrotic signaling and collagen production. These effects point toward a role for gentle, prolonged loading in regulating how connective tissue remodels over time.

Another important nuance is that stretching does not appear to merely suppress initial inflammation, but may help guide its resolution once it is underway. Some studies have found that stretching not only reduces inflammation, but may also help the body move more quickly toward recovery.¹⁴

More recent research in fascia and connective tissue biology provides a broader context for these findings. The extracellular matrix is now understood to be a dynamic, hydrated environment in which fluid movement, molecular organization, and cellular signaling are all time-dependent processes.¹⁵ Changes in tissue hydration, viscosity, and glide continue to evolve over minutes, rather than being completed within seconds.¹⁶ At the same time, mechanosensitive pathways within cells can remain active under ongoing mechanical stress and may contribute to longer-term cellular changes, as seen in broader mechanobiology research.¹⁷

While emerging research in mechanobiology suggests that sustained loading can influence fibroblast activity and connective tissue behaviour, the precise dose-response relationship in humans remains unclear. There is still more research to do, but taken together these current lines of evidence suggest that long-duration, low-intensity stress occupies an important place on the spectrum of mechanical inputs. It operates through mechanisms that differ from those of short, high-intensity loading. The response has less to do with peak force and more to do with cumulative exposure, fluid dynamics, and cellular signaling. While much of this work remains at the level of animal models and basic science, the consistency of the findings supports a simple conclusion: sustained mechanical loading is biologically active, and its effects cannot be dismissed just because the stress is applied for longer durations.

Time is not a boundary

What emerges from this spectrum is a nuanced understanding of time: it is not a threshold which, when crossed, nothing further happens. It is one dimension of a multidimensional dose. Short, intense loads and long, gentle loads both have value, but they act through different pathways. The mistake is not in valuing one over the other, but in assuming that one renders the other irrelevant.

When it is suggested that little of significance happens after a load is maintained beyond 60 seconds, this is valuing only a single point along this spectrum. It is treating tissue response as if it were binary: active up to a minute, inactive thereafter. But the biology does not support that view. Mechanical responses, fluid shifts, cellular signaling, and gene expression unfold over different time scales. Some begin quickly and plateau. Others require sustained input to develop and persist.

A more accurate way to think about it is this: the body is always responding, but how it responds depends on how and for how long the load is applied. Duration does not stop mattering at 60 seconds. It simply begins to matter in different ways.

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FOOTNOTES

¹ A Delphi consensus is a structured method in which a panel of experts reviews evidence and provides feedback over multiple rounds, refining their views until a defined level of agreement is reached. It reflects informed expert consensus rather than direct experimental proof. See Warneke K, Thomas E, Blazevich AJ, Afonso J, Behm DG, Marchetti PH, Trajano GS, Nakamura M, Ayala F, Longo S, Babault N, Freitas SR, Costa PB, Konrad A, Nordez A, Nelson A, Zech A, Kay AD, Donti O, Wilke J. Practical recommendations on stretching exercise: A Delphi consensus statement of international research experts. J Sport Health Sci. 2025 Dec;14:101067. doi: 10.1016/j.jshs.2025.101067. Epub 2025 Jun 11. PMID: 40513717; PMCID: PMC12305623

² Down-regulation of the nervous system / reduced neural drive refers to a temporary decrease in the activity of the nervous system, particularly the signals sent from the brain to the muscles. After prolonged or intense stretching, the body may reduce muscle activation and reflex responsiveness, leading to a short-term decrease in strength, speed, and coordination. This effect is typically transient and returns to normal with movement or activity.

³ The Delphi consensus cited above concluded, “The panel does not recommend prolonged (>60s per muscle) static stretching prior to maximal or explosive contractions in isolated muscle groups … However, short-duration static stretching incorporated into a dynamic warmup and dynamic stretching do not cause such impairments.”

⁴ Cao, T. V., M. R. Hicks, M. Zein-Hammoud, and P. R. Standley. “Duration and Magnitude of Myofascial Release in 3-Dimensional Bioengineered Tendons: Effects on Wound Healing.” Journal of the American Osteopathic Association 115, no. 2 (2015): 72–82. This study demonstrated that both the duration and magnitude of applied mechanical strain influenced fibroblast activity and collagen organization, supporting the concept that tissues respond to the overall dose of mechanical loading, not a single variable in isolation.

⁵ Creep and stress relaxation are time-dependent properties of viscoelastic tissues. Creep refers to the gradual lengthening of a tissue when a constant load is applied over time. Stress relaxation refers to the gradual decrease in internal tension within a tissue when it is held at a constant length. Both processes continue over time, not just in the first few seconds of a stretch. For a deeper understanding see my articles on Creep (https://yinyoga.com/creep-and-counterposes/) and Viscoelasticity (https://yinyoga.com/a-viscoelastic-primer-for-yin-yogis/ ).

⁶ In addition to fibers, connective tissues contain a large amount of water within the extracellular matrix. Over time, sustained loading allows this fluid to shift and redistribute, influencing tissue hydration, lubrication, and the ability of adjacent layers to slide past one another. These fluid-related changes develop gradually, which is why longer durations can have different effects than brief stretches.

⁷ To learn more about static progressive stress (SPS) read: https://yinyoga.com/static-progressive-stress-and-yin-yoga/

⁸ David A. Schwartz, “Static Progressive Orthoses for the Upper Extremity: A Comprehensive Literature Review,” Hand 7, no. 1 (2012): 10–17.

⁹ Helene M. Langevin, et al., “Stretching Promotes Resolution of Inflammation in Connective Tissue,” Journal of Cellular Physiology 232, no. 8 (2017): 2147–2159.

¹⁰ Corey M. Berrueta, et al., “Stretching Reduces Tumor Growth in a Mouse Breast Cancer Model,” Scientific Reports 8 (2018): 7864.

¹¹ Helene M. Langevin, et al., “Fibroblast Cytoskeletal Remodeling Induced by Tissue Stretch Involves ATP Signaling,” Journal of Cellular Physiology 228, no. 9 (2013): 1922–1931.

¹² Helene M. Langevin, “The Science of Acupuncture,” The Scientist, April 30, 2013, https://www.the-scientist.com/the-science-of-acupuncture-39379

¹³ Helene M. Langevin, et al., “Stretching Reduces Inflammation and Improves Gait in a Rat Model of Inflammation,” PLOS ONE 6, no. 10 (2011): e29831.

¹⁴ Helene M. Langevin, et al., “Stretching Promotes Resolution of Inflammation in Connective Tissue,”
Journal of Cellular Physiology 232, no. 8 (2017): 2147–2159.

¹⁵ Carla Stecco, et al., Functional Atlas of the Human Fascial System (Edinburgh: Elsevier, 2015).

¹⁶ Catharina Fede and Carla Stecco, “The Fascial System and Its Role in Movement and Disease,” International Journal of Molecular Sciences 23, no. 17 (2022): 10127.       

¹⁷ Stefano Piccolo, et al., “YAP/TAZ as Mechanotransducers in Tissue Homeostasis and Disease,” Nature Reviews Molecular Cell Biology 15 (2014): 789–803.