Beyond my PE routine, I've learned there's a few key principles that can accelerate or hinder growth and the margin of error feels narrow. I've seen a lot of discussions on strain, but have not found anything authoritative so here's my attempt to provide some guidance based on analogous medical research.
Safe Strain & Heat for Connective-Tissue Remodeling
My first three years of PE were slow and difficult. Since returning to PE, 10+ years later, I’ve changed my routine and my approach and I've had far better results. So what changed? Mostly, my level of strain, how and when I apply heat, and even my approach to deconditioning. My gains recently stalled, so I dug into the medical research outside of PE to gain clarity on how to maximize my PE gains. I used too much strain during my first years of PE, and in recent times I've often not used enough strain. In other words, I suspect I could have gained even faster this second time around. I've often only used 1-2% strain in the last 1.7 years, and this yielded far better results than my first 3 years of PE. Anecdotally, based on my own experience, its best to err on the side of strain that's a little too low vs too high, but I am also finding that my gains seem faster when I'm in the 3-3.5% strain sweet spot. I find it difficult to continually achieve ideal strain; both time and tension must increase to continue to reach the right ideal level of strain. Of course, BPFSL continues to grow as well (it's a moving target).
- PE years ago: 3 years for 0.75" BPEL and 1" BPFSL (high strain)
- PE recently: 1.7 years for 1" BPEL and 2.1" BPFSL (low to moderate strain)
PE Fundamentals
To maximize gains with any PE approach, here's fundamental principles you can apply:
1. Strain – Maximize growth rates by targeting the ideal strain zone with a consistent routine. Make the most of every routine with ~3–3.5% strain → best balance of growth & safety.
2. Heat – Always use it; it’s crucial. But too much can backfire. Stay warm (38–42 °C / 100–108 °F) for maximum plastic response.
3. Cementing – Gains must be stabilized or they will retract. Don't quit right when you reach your goal; continue at least 90 days more.
4. Deconditioning – Sometimes a reset is needed to restore tissue plasticity. Some take a 4-6 week break once a year, others only after hitting a hard plateau. Cold turkey isn’t the only option — very low strain (e.g. 1-2%) can also reset tissues while helping preserve gains.
Strain Theory & Application
Step 1: Measure your bone-pressed flaccid stretch length (BPFSL) before you start.
Step 2: Measure again immediately after finishing, same way.
Formula: Strain % = (After – Before) ÷ Before × 100
Example:
- Before PE routine: 8.6″ BPFSL
- After PE routine: 8.875″ BPFSL
- Calculation: (8.875 – 8.6) ÷ 8.6 = 3.2% strain
- → Right in the 3–3.5% target zone for growth without stiffening.
Strain Ranges
< 2% strain → Too low → mostly maintenance, glacial gains, partial deconditioning.
~3.0–3.5% strain → Sweet spot → plastic creep, elongation stimulus, minimal stiffening.
~3.6–4% strain → Still productive, but nearing stiffening threshold.
~4.0-4.4% strain → Gray zone (avoid). Micro-failure can begin around 4% in some tendons (esp. flexors)
≥ 4.5% strain → Strengthening zone → collagen cross-linking, tissue stiffening, plateau risk.
≥ 8% strain → Degeneration & injury risk.
Heat
- Always use heat — without it, tissues resist elongation and gains slow dramatically.
- Optimal range: 38–40.5 °C (100–105 °F) → boosts collagen plasticity, lowers injury risk.
- Grey zone: 41–41.5 °C (106–107 °F) → unsafe if this is a surface reading an internals are 2-3 degrees higher.
- Danger zone: ≥42 °C (≥108 °F) → denatures proteins, shrinks collagen, reduces elasticity.
Cementing Gains
- New length gains stabilize over ≈ 8–12 weeks of continued loading.
- Stop too soon → recent gains retract (“uncemented” collagen).
- Best practice: Maintain 1–2% strain for 3 months post-gain to lock it in.
Deconditioning
- Complete rest (4–6 weeks): fastest stiffness reduction, but risks loss of recent gains.
- Low-strain “active deload” (1–2% for 6–8 weeks): slower reset, but maintains elongation and circulation.
- Note: I’ve personally made slow, but measurable BPFSL gains with only 1–2% strain.
Conclusion
The fundamentals of PE success are straightforward: strain in the right zone, consistent use of heat, cementing gains, and smart deconditioning. The sweet spot is narrow, but if you stay inside it you maximize gains while minimizing risk. This write-up is not just guesswork — it’s drawn from biomechanics, tendon and fascia research, clinical traction studies, and personal experience. While no one is publishing “strain theory” or "heat theory" for PE in medical journals (yet), the principles of connective tissue remodeling are the same.
References
Strain & Tissue Remodeling
- Danto MI, Woo SLY. The mechanical properties of skeletally mature rabbit ACL and patellar tendon over a range of strain rates. J Orthop Res. 1993;11(1):58-67.
- Johnson GA, Tramaglini DM, Levine RE, et al. Tensile and viscoelastic properties of human patellar tendon. J Orthop Res. 1994;12(6):796-803.
- Wang JHC. Mechanobiology of tendon. J Biomech. 2006;39(9):1563-1582.
Heat & Collagen Plasticity
- Knight CA, Rutledge CR, Cox ME, et al. Effect of superficial heat, deep heat, and active exercise warm-up on muscle extensibility. Phys Ther. 2001;81(6):1206-1214.
- Lehmann JF, Masock AJ, Warren CG, Koblanski JN. Effect of therapeutic temperatures on tendon extensibility. Arch Phys Med Rehabil. 1970;51(8):481-487.
Deconditioning & Training Effects
- Kubo K, Ikebukuro T, Maki A, et al. Time course of changes in the human Achilles tendon properties and metabolism during training and detraining in vivo. J Appl Physiol. 2012;112(11):1875-1881.
- Kubo K, Ikebukuro T, Yata H, et al. Time course of changes in muscle and tendon properties during detraining. J Appl Physiol. 2010;109(5):1105-1111.
Penile Traction Therapy
- Levine LA, Newell MM, Taylor FL. Penile traction therapy for treatment of Peyronie's disease: a single-center pilot study. J Sex Med. 2008;5:1468-1473.
- Gontero P, Di Marco M, Giubilei G, et al. A pilot phase-II prospective study to test the efficacy and tolerability of a penile-extender device in the treatment of "short penis." BJU Int. 2009;103(6):793-797.
