Does Alpha-GPC Affect Isometric Strength? [6 Days Study]


Extreme moments of force and power production determine a lot of a sport’s performance.

The majority of this is due to increased muscular strength, but training can also cause changes in the brain.

When performing the eccentric exercise, researchers found that torque increased due to central (or neural) adaptation, according to Pensini, Martin, and Maffiuletti.

According to what we know right now, athletes need both central and peripheral adaptations to improve their performance. Because of this, nutritional interventions that can improve either site of adaptation should be researched.

An ingredient in glycerylphosphorylcholine (Alpha-GPC) may improve human performance by improving neuro-muscular communication.

Following exhaustive exercise, rats in the central nervous system (CNS) exposed to Alpha-GPC had higher levels of the neurotransmitter acetylcholine, which was found to increase their reaction time.

Additionally, moderate to high doses of Alpha-GPC is generally considered safe.

Choline is produced when ingested Alpha-GPC is converted to phosphatidylcholine. Dietary choline intake is associated with acetylcholine biosynthesis.

To put it another way, because cholinergic nerves are responsible for muscle contraction, substances that increase choline availability may have an impact on muscular performance.

However, there is a lack of information on the ability of compounds like Alpha-GPC to enhance performance in the short term.

This study’s goal was to see what effect taking Alpha-GPC for six days had on isometric force production measurements in the upper and lower body.


The University of Louisiana at Lafayette’s Institutional Review Board examined the current investigation for ethical issues.

The study included 13 healthy college-aged males as participants. The study was double-blind, placebo-controlled with a one-week washout period, and the subjects were all healthy.

As previously described in previous studies, subjects reported to the lab and provided informed consent that included consent to publish prior to baseline assessments that included height and weight, an assessment of maximum aerobic capacity via the COSMED CPET system (COSMED, Rome ITL), and body fat percentage via air displacement plethysmography (Bod Pod Gold Standard System, COSMED Rome, ITL).

Trial one (placebo or 600 mg of A-GPC in random order) began the following week.

They were given an initial dose (placebo or A-GPC) while in the lab and the performance testing (isometric mid thigh pull, upper body isometric test) was repeated one hour later.

For the trials, this was done as a baseline. After that, the participants took a pre-packaged supplement for six days (morning and evening).

Subjects returned on the sixth day of this period for the second round of performance testing.

One week of washout followed by another round of testing with an alternative treatment.


The subjects were given 600 mg of A-GPC (AlphaSize®, ChemiNutra, Austin, TX) or a placebo for eight weeks.

Both treatments were given in gel caps of the same color and in the same dosage form (white).

The number of active ingredients in the A-GPC capsules was verified by a certificate of analysis from a third-party lab. Microcrystalline cellulose and magnesium stearate were the only ingredients in the placebo capsule (Nature’s Supplements, Carlsbad, CA, USA).

Until the end of the study, neither the participant nor the researcher knew which treatment they were receiving.

These pills came in an unmarked plastic bottle with only a code on it, and participants were instructed to take them twice each day, in the morning and evening, for a total of 600 mg of A-GPC per day.

After the research was completed, the bottles were given back to the participants.

Participants said they took the medication as prescribed with no problems.

Hamstring pull-ups with an isometric stance (IMTP)

IMTP is a well-researched and widely used strength test. An AMTI Force Plate was placed on a concrete laboratory floor and tested in a custom power rack (built by Rogue Fitness, Columbus, USA) (Advanced Materials Technologies Inc., Watertown, USA).

For a steel bar that is secured by two large tubular steel members, the power rack allows for small incremental height adjustments.

A force plate was placed in front of the participant, and he was instructed to stand with his feet shoulder-width apart. It was found that when holding the bar with straight arms, the participant’s torso was upright (determined using a contractors box level), their knees were flexed to a range of 120–130°, and their arms were straight.

Instructed participants were instructed to “drive straight up” and “pull as hard as they could” against the chain until the force began to noticeably diminish.

An AMTI Force Plate was used to measure the maximum force at a sampling rate of 2000 Hz.

During the first visit to the lab, subjects learned about the IMTP.

Measurements were made three times with a five-minute break in between each measurement.

Isometric exercise of the upper body (UBIST)

A load cell was installed on the lab floor and the participants were positioned on three elevated platforms with their chests hanging directly over them (iLoad Pro, Loadstar Sensors, Fremont CA).

Load cell accuracy was initially listed as 0.25 percent for a full-scale measurement with a capacity of over 5000 N.

For the participants, push-ups were performed with hands at 150 percent of acromial width and elbows extended to 90 degrees (as measured with a goniometer).

The load cell was tethered to a chain by a thick, non-elastic strap that was run over one shoulder and under the other.

Researchers told the participants that they had to keep their backs flat while pushing as hard as they could with their hands until they were told to stop.

Data was captured after the load cell had been tared to make sure that its own weight was taken into account. Research began with a verbal “push as hard as possible” from the participant.

During the data collection, the participants were verbally encouraged until the force production dropped by 50 N from the maximum value recorded.

A maximum data rate of 150 Hz was set on the load cell, and the data was exported to and analyzed in JMP 11.0. (SAS Institute Inc, Cary NC).

The data was parsed to extract peak values, which were then used in the analysis that followed.

It was administered three times with a five-minute break in between each attempt. This test has been validated and found to be reliable in the literature.

A study based on statistics

When it came to the isometric tests, reliability was evaluated using Intra Class Correlation Coefficients (ICC).

Measures that are taken repeatedly Ancovas were used to look at short-term (1-hour post-treatment) and long-term (6-day post-treatment) changes in performance.

Placebo came first, followed by A-GPC, and then the order of administration was included as a covariate in the model. Although G*Power software was utilized to calculate effect size (Cohen’s d), a modern statistical software package was used for all other analyses (JMP, version 11.0 SAS Institute Inc., Cary, NC).

They calculated magnitude-based inferences to aid in the interpretation of the data.

Using magnitude-based inference aims to broaden the range of possible interpretations of findings beyond just significant and non-significant.

A more traditional statistical approach will be used in conjunction with this interpretation, as it is not without controversy.


Isometric tests’ dependability

When the triplicate measurements were examined by ICC (with a range of 0.969–0.984), the isometric tests showed their reliability. Throughout the experiment, there were no significant differences in the measurements.

In subsequent analysis, the highest value from the three measures was used.

Adverse drug reactions (acute)

No main effects or interaction effects of treatment*time (F = 0.003, p = 0.9584) were found for IMTP performance 1 hour after the initial dose of A-GPC or placebo, according to Anova.

When UBIST performance was examined, the same conclusions were drawn.

Chronic side effects of treatment

Measures that are taken repeatedly It turned out that there was a significant interaction effect between treatment (A-GPC vs Placebo) and time (baseline, day six) for the peak performance of IMTP when using ANOVA (F = 3.12, p = 0.04; change from baseline A-GPC: 98,8.

A-GPC treatment resulted in a greater change from baseline force production (A-GPC: 50.9 167.2 N Placebo: 14.9 114.9 N), but the interaction between treatment and time was not statistically significant (F = 1.36, p = 0.0127) for the upper body test.

This suggests that the subject’s variability in upper-body strength limited the statistical power, but it is likely that there is a real effect in this data.

According to magnitude-based inferences, the A-GPC was likely beneficial in increasing upper body isometric force by 68.3% and lower body isometric force production by 86.5%.


According to the findings of this study, A-GPC can be used to boost strength, especially in the lower body, after six days of taking a 600 mg dose of it.

A-GPC has not yet been thoroughly studied for its effects on aspects of human performance directly linked to isometric strength, so this study represents an important first step in the product’s evaluation for this specific application.

A small body of research suggests that choline may be an important consideration for endurance athletes.

There is some information on A-GPC and performance measurements in the current literature.

According to Jagim et al., a multi-ingredient supplement containing A-GPC increased mean sprint power on a non-motorized treadmill but did not affect counter-movement jumping performance peak or mean power during the maximal effort sprint test.

At 200 mg or 400 mg, a-GPC did not statistically improve performance, but Parker et al. found a non-significant trend in vertical jump peak power after acute supplementation with 200 mg or 400 mg of A-GPC.

It was discovered that giving men with two years of training experience 600 mg of A-GPC for a short period of time increased their bench press power.

The results of this study are similar to those of the current investigation in A-GPC administered dose (600 mg) and suggest that performance has been improved.

The designs, measurements, and administrations used in the previous studies on A-GPC were all quite different. Possibly, the inconsistent results are due to a lack of consistency in the doses (200–600 mg) and administration time (30–90 min before activity).

Further research is needed to confirm the experiment’s findings, but the preliminary data is encouraging and suggests other applications for A-GPC.

Increased bioavailability of choline, which could lead to increased acetylcholine synthesis in neurons, is one mechanism by which A-GPC might improve strength and power performance.

Acetylcholine levels in CNS neurons were found to be elevated when A-GPC was administered.

One study shows A-GPC increases plasma choline levels when given intramuscularly. There’s evidence that acetylcholine stimulation of catecholamine release by A-GPC increases growth hormone secretion.

Increased cholinergic tone and growth hormone release were also seen in older and younger subjects who were given A-GPC and the growth hormone-releasing hormone.

Increasing growth hormone for seven days had no effect on maximum strength, but this evidence suggests that longer chronic studies of A-GPC may be warranted given that chronic elevations in growth hormone could potentially enhance performance even further in the present investigation.

A-GPC has the potential to increase strength, but the current research shows that it has some limitations.

The present study is constrained by the number of participants it has.

Other measures of human performance, likely those that have the capacity to measure power rather than just peak strength, will need to replicate the study.

And different doses of A-GPC need to explore any possible dose-response, or lower limit for meaningful effect, to be determined. This is necessary. Further in vitro research may be needed to show that A-GPC increases levels of neurotransmitters in motor neurons.

As a result of these studies, dosing schemes with more precise and informed timing for A-GPC administration may be developed.


The study’s findings suggest that supplementing with A-GPC for 6 days increases lower body force production.

Statistical significance was not achieved for a similar trend in upper body isometric strength.

Given that in many sports, a 2% change in performance can have a significant impact on results, it’s important to note that after 6 days of A-GPC, lower body isometric strength increased by more than 3%.

A-GPC can be added to the diets of speed and power athletes by sports performance coaches to improve muscle performance.



Recent Posts

error: Content is protected !!