Short-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon: differential effects of specific contraction types.

Heinemeier KM, Olesen JL, Schjerling P, Haddad F, Langberg H, Baldwin KM, Kjaer M

Journal of applied physiology (Bethesda, Md. : 1985)12 Oct 2006Cited by 135 (Europe PMC)

PMID17038487DOI10.1152/japplphysiol.00866.2006PepBankPUB-17038487

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Summary

The text of this summary is not shown here, because the article license does not allow reuse. Read it at the source (opens in a new tab)

Text rights: Publisher copyright. Results still quote short attributed sentences.

Results from this study4

No result from this study comes from a test of the peptide.

Natural levels measured4

These results measure the body's own peptide. Nobody was given the peptide. They are not evidence about taking it. They are left out of key results, evidence counts and charts.

01AnimalEndogenous levelAnimal study (in vivo)Mechanism
In rats, 4 days of concentric, eccentric or isometric training increased muscle mRNA of IGF-IEa and MGF (up to 15-fold, reported for both transcripts together).
In plain wordsIn rats, short strength training raised the body's own MGF levels in muscle.
Peptide
MGF / PEG-MGF
Outcome
IncreaseMGF mRNA in muscle after training
Study
ratn: not reported in source
Female Sprague-Dawley rats, stimulated gastrocnemius
Outcome group
Muscle injury and repair · Musculoskeletal
Source sentences
Summary
IGF-IEa and MGF increased in muscle (up to 15-fold) and tendon (up to 4-fold) in response to training (P < 0.01)
1 context sentence(design, population, supporting numbers)
Summary · context
Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured…
This result measures the body's own MGF / PEG-MGF. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-1703848701
02AnimalEndogenous levelAnimal study (in vivo)Mechanism
In rats, short-term training increased Achilles tendon mRNA of IGF-IEa and MGF (up to 4-fold, reported for both transcripts together).
In plain wordsIn rats, short strength training raised the body's own MGF levels in tendon.
Peptide
MGF / PEG-MGF
Outcome
IncreaseMGF mRNA in tendon after training
Study
ratn: not reported in source
Female Sprague-Dawley rats, stimulated gastrocnemius
Outcome group
Muscle injury and repair · Musculoskeletal
Source sentences
Summary
IGF-IEa and MGF increased in muscle (up to 15-fold) and tendon (up to 4-fold) in response to training (P < 0.01)
1 context sentence(design, population, supporting numbers)
Summary · context
Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured…
This result measures the body's own MGF / PEG-MGF. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-1703848702
03AnimalEndogenous levelAnimal study (in vivo)Mechanism
In rat muscle, eccentric training increased MGF mRNA more than concentric training.
In plain wordsIn rats, eccentric training raised the body's own MGF in muscle more than concentric training.
Peptide
MGF / PEG-MGF
Outcome
IncreaseMGF mRNA in muscle, eccentric versus concentric training
Study
ratn: not reported in source
Female Sprague-Dawley rats, stimulated gastrocnemius
Comparator
Concentric training
Outcome group
Muscle injury and repair · Musculoskeletal
Source sentences
Summary
In tendon no difference was seen between training types, but in muscle the effect of eccentric training was greater than concentric training for both IGF-IEa and MGF (P < 0.05), and for IGF-IEa isometric training had greater effect than concentric (P < 0.05).
1 context sentence(design, population, supporting numbers)
Summary · context
Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured…
This result measures the body's own MGF / PEG-MGF. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-1703848703
04AnimalEndogenous levelAnimal study (in vivo)Mechanism
In rat Achilles tendon, MGF mRNA did not differ between training types.
In plain wordsIn rats, the body's own MGF in tendon did not differ between types of training.
Peptide
MGF / PEG-MGF
Outcome
No significant changeMGF mRNA in tendon, between training types
Study
ratn: not reported in source
Female Sprague-Dawley rats, stimulated gastrocnemius
Comparator
Other training types
Outcome group
Muscle injury and repair · Musculoskeletal
Source sentences
Summary
In tendon no difference was seen between training types
1 context sentence(design, population, supporting numbers)
Summary · context
Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured…
This result measures the body's own MGF / PEG-MGF. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-1703848704

AI wrote and checked these results. AI can make mistakes, so check important results against the source.

Version history

PepBank keeps every version of the data on this study. Status changes from Retraction Watch, Europe PMC and Crossref are listed with their source.

Version 2Current
13 Oct 2026, 21:44 UTC
Study results updated
Version 1
13 Oct 2026, 16:31 UTC
First added · source update from Europe PMC

Subjects

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