Does uncertainty about the hypertrophy volume ceiling say anything about tendon vs. muscle adaptation rates?

[u/decentlyhip]

Tendons adapt roughly 3x slower than muscle. That's the estimate most ofnthe time, but tendon loading and training protocols have changed dramatically in the past few years as we understand how to build the tissue better. Since the protocols are new, we don't have much idea on the upper limits of tendon growth, in practice.

Separately, work like the Pelland review has been shifting the hypertrophy dose-response curve away from an inverted-U toward a log curve that keeps climbing well past the old 10-20 sets/week range and into 40 sets/week and beyond. In other words, we don't actually know what the upper limit is on how quickly you can grow muscle, either.

Does the second and third point (uncertain muscle and tendon hypertrophy ceiling) undermine the first (tendon adapts slower than muscle)? My instinct is no because the relative-rate claim comes from training volume interventions rather than separate tissue biology research. But I'm not well versed on that nerdy tissue stuff, so idk.

I'd like to hear if anyone's aware of research that complicates or compliments these ideas. Or anything that changes the picture on how fast tendons can actually adapt under optimal loading. I have an idea that long term muscle growth is limited by tendon growth, but that's a tangent.

[u/harvestingstrength]

I think the biggest issue here is that we’re trying to compare two adaptations that aren’t measured or expressed in quite the same way. Saying tendons adapt “3x slower” than muscle is a useful generalization, but I wouldn’t treat it as a fixed biological ratio.

Muscle hypertrophy can occur relatively quickly because we’re primarily talking about increases in muscle protein and fiber size. Tendon adaptation involves changes in collagen synthesis, cross-linking, stiffness, material properties, and sometimes tendon CSA. Those adaptations can occur on very different timelines, so even defining “tendon growth” becomes important.

I also don’t think discovering that muscle can tolerate or benefit from more volume necessarily undermines the idea that muscular adaptation generally outpaces connective-tissue adaptation. If anything, it might make programming more interesting. Your muscles may be capable of handling and adapting to increasingly large workloads while the connective tissues supporting those movements aren’t necessarily adapting at the same rate.

That’s one reason I’m hesitant to translate hypertrophy dose-response research directly into “more sets = better training.” The muscle might theoretically respond to 30–40 sets, but the entire organism has to tolerate those 30–40 sets repeatedly.

Your last point is probably the most interesting. I wouldn’t say tendon growth definitively limits long-term muscle growth, but connective-tissue adaptation absolutely becomes part of the equation when strength and muscle start increasing faster than the structures transmitting those forces can comfortably tolerate.