Will this replace heavy lifting?

No. In climber studies, low-load holds and heavy max hangs each produced about a 3 percent grip strength gain and the combination produced about 6 percent. They train different parts of the system, so run both.

Can I do tendon isometrics during a competition or race week?

Yes, and that is one of the main advantages. Sustained isometrics create almost no delayed-onset soreness, so they maintain connective tissue quality without the fatigue cost of heavy eccentrics.

How long before I feel a difference?

Pain relief in a cranky tendon can show up within a session or two. Actual structural change is slow. Collagen remodelling takes months, so plan on at least 12 weeks of consistent work before judging results.

Should I do this if my tendon already hurts?

Isometrics are frequently used early in tendinopathy rehab and often reduce pain. But if the pain is sharp, one-sided, worsening week over week, or present at rest, see a physiotherapist first. A protocol is not a diagnosis.

The 50% Rule for Stronger Tendons

The 50% Rule for Stronger Tendons from CrossFit BC. Half effort, held for 30 seconds, beats max effort for tendon health. The science behind low-load long-duration isometrics, and how to program them in a…

Written by:: CrossFit BC Coaching Team
Section:: Training
Reading time:: 10 min
Topics:: tendons, isometrics, injury prevention, strength, recovery, longevity
Published:: Saturday, August 1, 2026
Last updated:: Saturday, August 8, 2026

The 50 Percent Rule: Low-Load Isometrics Build Stronger Tendons

This article is part of the CrossFit BC journal, written by the coaching staff who run our classes in Olympic Village, Vancouver. We publish what we teach on the floor: training decisions, recovery, nutrition, and the honest tradeoffs behind them.

Common questions

What is a low-load long-duration isometric?

A held position at roughly 50 percent of your maximum effort, sustained for about 30 seconds, with the force ramped up over three seconds and released over three seconds. Four sets per position, three days a week.

Why is 50 percent better than maximum effort for tendons?

At maximum effort the strongest tendon fibres absorb almost all the load and the weaker fibres are never stressed. Holding a moderate load lets those stiff fibres creep, which progressively transfers tension onto the rest of the tendon so the whole structure gets the remodelling signal.

How do I know I am at 50 percent without equipment?

Use effort as your dial. It should feel like a 5 out of 10, you should be able to talk normally through the hold, and second 25 to 30 should feel like work but never like failure. If you cannot finish the 30 seconds cleanly, reduce the load, not the time.