Myth short cycles needed to prevent myostatin increasing
Posted: Sat Jul 17, 2021 9:23 pm
There is a common misbelief that myostatin increases the longer you are on cycle. The study I am about to post shows that that's not true.
They gave doses of up to 600 mg Test for 20 weeks and found that myostatin spiked at week 8 (day 56) but when they measured myostatin concetration at week 20 (day 140) it was back to baseline even in the 600 mg group. From this information we can conclude that longer, lower dose cycles are probaly more effective then shorter, high-dose ones.
Methodological problems, including binding of myostatin to plasma proteins and cross-reactivity of assay reagents with other proteins, have confounded myostatin measurements. Here we describe development of an accurate assay for measuring myostatin concentrations in humans. Monoclonal antibodies that bind to distinct regions of myostatin served as capture and detector antibodies in a sandwich ELISA that used acid treatment to dissociate myostatin from binding proteins. Serum from myostatin-deficient Belgian Blue cattle was used as matrix and recombinant human myostatin as standard. The quantitative range was 0.15–37.50 ng/mL. Intra- and inter-assay CVs in low, mid, and high range were 4.1%, 4.7%, and 7.2%, and 3.9%, 1.6%, and 5.2%, respectively. Myostatin protein was undetectable in sera of Belgian Blue cattle and myostatin knockout mice. Recovery in spiked sera approximated 100%. ActRIIB-Fc or anti-myostatin antibody MYO-029 had no effect on myostatin measurements when assayed at pH 2.5. Myostatin levels were higher in young than older men (mean ± S.E.M. 8.0 ± 0.3 ng/mL vs. 7.0 ± 0.4 ng/mL, P = 0.03). In men treated with graded doses of testosterone, myostatin levels were significantly higher on day 56 than baseline in both young and older men; changes in myostatin levels were significantly correlated with changes in total and free testosterone in young men. Myostatin levels were not significantly associated with lean body mass in either young or older men.
Conclusion
Myostatin ELISA has the characteristics of a valid assay: nearly 100% recovery, excellent precision, accuracy, and sufficient sensitivity to enable measurement of myostatin concentrations in men and women.
They gave doses of up to 600 mg Test for 20 weeks and found that myostatin spiked at week 8 (day 56) but when they measured myostatin concetration at week 20 (day 140) it was back to baseline even in the 600 mg group. From this information we can conclude that longer, lower dose cycles are probaly more effective then shorter, high-dose ones.
Methodological problems, including binding of myostatin to plasma proteins and cross-reactivity of assay reagents with other proteins, have confounded myostatin measurements. Here we describe development of an accurate assay for measuring myostatin concentrations in humans. Monoclonal antibodies that bind to distinct regions of myostatin served as capture and detector antibodies in a sandwich ELISA that used acid treatment to dissociate myostatin from binding proteins. Serum from myostatin-deficient Belgian Blue cattle was used as matrix and recombinant human myostatin as standard. The quantitative range was 0.15–37.50 ng/mL. Intra- and inter-assay CVs in low, mid, and high range were 4.1%, 4.7%, and 7.2%, and 3.9%, 1.6%, and 5.2%, respectively. Myostatin protein was undetectable in sera of Belgian Blue cattle and myostatin knockout mice. Recovery in spiked sera approximated 100%. ActRIIB-Fc or anti-myostatin antibody MYO-029 had no effect on myostatin measurements when assayed at pH 2.5. Myostatin levels were higher in young than older men (mean ± S.E.M. 8.0 ± 0.3 ng/mL vs. 7.0 ± 0.4 ng/mL, P = 0.03). In men treated with graded doses of testosterone, myostatin levels were significantly higher on day 56 than baseline in both young and older men; changes in myostatin levels were significantly correlated with changes in total and free testosterone in young men. Myostatin levels were not significantly associated with lean body mass in either young or older men.
Conclusion
Myostatin ELISA has the characteristics of a valid assay: nearly 100% recovery, excellent precision, accuracy, and sufficient sensitivity to enable measurement of myostatin concentrations in men and women.
