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

Written on November 19, 2022 by | Reviewed by William Gallagher, MNeuroSci

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.


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%.


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.