ResearchSafe

Tendon soreness after low‑dose myostatin inhibitor – anyone else see this?

Posted by theo_benchpr in Safety & Side Effects - 13 points, 4 comments.

I started a 4‑week trial of a myostatin‑inhibitor peptide a few months ago. My plan was 100 mcg subcutaneously three times a week, rotating sites. For the first two weeks I felt a little extra “pump” and my bench numbers crept up a pound or two. By week three I noticed a dull ache in my Achilles and the tendons around my knees, especially after leg days. The pain wasn’t sharp, more of a stiffness that lingered into the next day. I switched to 50 mcg and added a rest day after heavy squats, and the soreness eased a bit, but didn’t disappear completely.

I’ve been checking my blood work – everything looks normal, no CK spikes. Has anyone experienced similar tendon stress with myostatin blockers? Should I cut the dose further or add supportive supplements? Open to any safety tips.

Comments

  • kyle_reads: i had a short trial with a myostatin‑blocking peptide a while back, 80 µg twice a week. after about ten days I also felt some mild achilles tightness, especially when I added plyo jumps. my own tweak was to add collagen peptide (10 g) and vitamin c 500 mg daily and to stretch calves right after training; the stiffness seemed to lessen after a week. i also cut the dose to 40 µg and kept the extra rest day, which made the ache almost disappear. maybe keep the dose low, watch volume, and consider
  • dita_h: i saw similar achilles tightness when i tried a low‑dose myostatin blocker, and the collagen + vitamin c combo you mentioned helped a bit for me too. i also found cutting the dose to around 50 µg and adding a dedicated calf stretch after squats reduced the stiffness noticeably. maybe keep the volume modest and monitor how your tendons feel.
  • theo_benchpr: Thanks, dita_h. I already dropped to 50 µg but haven’t been consistent with the calf stretch, just a quick shake‑out. I’ll add a proper stretch routine after squats and see if it eases the tightness. Did you notice any change in your squat volume when you cut the dose, or were you able to keep the same loads?
  • theo_benchpr: Thanks for the tip. I haven't tried collagen yet. The plyo jumps part is interesting. I'm mostly just doing heavy squats and presses, but maybe the volume is still too high for the tendons to keep up. I'll try adding the vitamin C and collagen to see if it helps with the stiffness. Did you feel any difference in your recovery time after cutting back to 40 mcg, or just the lack of ache?

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