Does creatine increase IGF-1 levels?

Research shows that creatine supplementation combined with resistance training increases local (intramuscular) IGF-1 mRNA expression. This is distinct from systemic (blood) IGF-1 levels, which may or may not change significantly. The local IGF-1 increase activates autocrine and paracrine growth signaling directly within muscle tissue.

How does IGF-1 promote muscle growth?

IGF-1 binds to IGF-1 receptors on muscle cells, activating the PI3K/Akt/mTOR signaling cascade. This pathway stimulates protein synthesis via mTORC1 activation, inhibits protein breakdown via FoxO transcription factor suppression, and promotes satellite cell proliferation and differentiation. The net result is muscle hypertrophy.

Is the IGF-1 increase from creatine similar to using growth hormone?

No. Creatine increases local muscle IGF-1 expression modestly and through natural physiological mechanisms (cell volumization, exercise enhancement). This is fundamentally different from pharmacological growth hormone administration, which raises systemic IGF-1 levels to supraphysiological concentrations. Creatine's effect is within the normal physiological range.

Creatine and IGF-1 Signaling: What to Know

IGF-1: The Growth Factor Connection

Insulin-like Growth Factor 1 (IGF-1) is one of the most potent anabolic hormones for skeletal muscle. While commonly associated with growth hormone (GH) signaling, IGF-1 is also produced locally within muscle tissue in response to mechanical and metabolic stimuli. Creatine supplementation has been shown to enhance this local IGF-1 production, providing a molecular mechanism for its muscle-building effects beyond simple energy buffering (RB et al., 2017) .

PI3K/Akt/mTOR

the primary intracellular signaling cascade activated by IGF-1 to drive protein synthesis and muscle growth

Kreider et al., 2017

Systemic vs Local IGF-1

Understanding the distinction between systemic and local IGF-1 is essential for interpreting creatine’s effects:

Systemic IGF-1 (Endocrine):

Produced primarily by the liver in response to growth hormone stimulation
Circulates in the blood bound to IGF-binding proteins (IGFBPs)
Affects multiple tissues throughout the body
Blood levels are relatively stable and reflect overall GH status

Local IGF-1 (Autocrine/Paracrine):

Produced by muscle cells themselves (and other tissues)
Acts on the producing cell (autocrine) or neighboring cells (paracrine)
Regulated by mechanical loading, metabolic stress, and cell volume changes
More directly relevant to exercise-induced muscle growth

Creatine’s primary effect on IGF-1 appears to be at the local level — increasing intramuscular IGF-1 mRNA expression rather than dramatically altering circulating blood levels. This local production is arguably more important for muscle hypertrophy because it creates high IGF-1 concentrations directly at the site where muscle growth occurs.

Mechanisms of IGF-1 Upregulation by Creatine

Several mechanisms may explain how creatine increases local IGF-1 expression:

1. Cell volumization:

Cell swelling from creatine-driven water influx triggers stretch-activated ion channels and integrin signaling
These mechanosensitive pathways upregulate IGF-1 gene transcription
The effect mimics the stretch stimulus that mechanical loading provides (T et al., 2011)

2. Enhanced training stimulus:

Creatine allows greater training volume (more reps, more sets) before fatigue
Greater mechanical loading is the primary stimulus for local IGF-1 production in muscle
The indirect effect through improved training may be as significant as direct molecular effects

3. Satellite cell activation:

Activated satellite cells produce and respond to IGF-1 in an autocrine/paracrine loop
Creatine’s known effect on increasing satellite cell number and activation amplifies this local IGF-1 signaling network

4. Gene expression changes:

Microarray studies have shown that creatine supplementation alters expression of hundreds of genes in muscle tissue
Several growth-related genes, including IGF-1 splice variants, show increased expression

The PI3K/Akt/mTOR Cascade

IGF-1 exerts its anabolic effects through a well-characterized intracellular signaling cascade:

Step 1: Receptor activation

IGF-1 binds to the IGF-1 receptor (IGF-1R), a receptor tyrosine kinase
The receptor autophosphorylates and recruits insulin receptor substrate (IRS) proteins

Step 2: PI3K activation

Phosphoinositide 3-kinase (PI3K) is activated by phosphorylated IRS
PI3K converts PIP2 to PIP3 at the cell membrane

Step 3: Akt activation

PIP3 recruits Akt (protein kinase B) to the membrane
Akt is phosphorylated and activated by PDK1 and mTORC2

Step 4: mTOR activation

Activated Akt phosphorylates and inhibits TSC2 (tuberous sclerosis complex 2)
TSC2 inhibition releases Rheb, which directly activates mTORC1

Step 5: Protein synthesis

Active mTORC1 phosphorylates p70S6K (ribosomal protein S6 kinase) and 4E-BP1
p70S6K activation enhances ribosomal translation capacity
4E-BP1 phosphorylation releases eIF4E, initiating cap-dependent mRNA translation
Net result: increased protein synthesis rate

Step 6: Anti-catabolic effects

Akt also phosphorylates and inactivates FoxO transcription factors
FoxO inactivation reduces expression of atrophy genes (atrogin-1, MuRF1)
This simultaneously inhibits protein degradation via the ubiquitin-proteasome pathway

Creatine and the IGF-1/mTOR Interaction

The relationship between creatine and the IGF-1/mTOR axis is synergistic (JD, 2003) :

Creatine increases local IGF-1 expression → feeds into PI3K/Akt/mTOR from the receptor level
Creatine-driven cell volumization → directly activates mTOR through volume-sensing mechanisms
Creatine improves training capacity → greater mechanical stimulus → more IGF-1 production and mTOR activation
Higher PCr → better energy support for the ATP-intensive process of protein synthesis downstream of mTOR

These converging inputs explain why creatine supplementation combined with resistance training produces greater hypertrophy than either intervention alone.

Clinical Relevance

The IGF-1 connection has implications beyond athletic performance:

Sarcopenia (age-related muscle loss) — older adults have reduced IGF-1 signaling; creatine may help compensate
Muscle wasting conditions — creatine’s IGF-1 enhancing effects could support muscle preservation
Recovery from injury — enhanced IGF-1 signaling promotes tissue repair
Metabolic health — IGF-1 signaling improves glucose uptake and insulin sensitivity

Summary

Creatine enhances local IGF-1 expression in muscle tissue through cell volumization, enhanced training stimulus, and satellite cell activation. This upregulated IGF-1 feeds into the PI3K/Akt/mTOR signaling cascade, driving protein synthesis and inhibiting protein degradation. The convergence of multiple creatine-mediated signals on the IGF-1/mTOR axis creates a potent anabolic environment that explains much of creatine’s documented muscle-building effects.