Evaluation of the effects of two doses of alpha glycerylphosphorylcholine on physical and psychomotor performance

Evaluation of the effects of two doses of alpha glycerylphosphorylcholine on physical and psychomotor performance

The present study was a double-blind, four arm investigation. The study procedures were reviewed and approved by the Institutional Review Board at the University of Louisiana at Lafayette and all participants gave written informed consent. Four groups of 12 healthy young men volunteered to participate in the study and were randomly assigned to groups (500 mg A-GPC, 250 mg A-GPC, 200 mg Caffeine or placebo). Flowchart of experimental procedures can be seen in Fig. 

1

.

Fig. 1

Flowchart of Experimental Procedures

Participants

A total of 48 apparently healthy college aged males volunteered to participant in the current investigation (see Table 

1

). The participants (

n

 = 48, height 177.6 ± 7.7 cm, weight 84.2 ± 14.4, BF% 15.3 ± 8.3, VO2 Max 33.8 ± 22.5 ml/kg*min) were recruited from the local University and represent a convenience sample of recreationally trained subjects. The group reported regular engagement in exercise to maintain or enhance fitness. Group means did not differ in major characteristics (

p

 > 0.5).

Table 1

Participant characteristics

Height (cm)

500 mg A-GPC

176.7 ± 8.7

0.64

250 mg A‐GPC

176.0 ± 6.6

200 mg Caffeine

179.7 ± 8.5

Placebo

178.9 ± 7.3

Weight (kg)

500 mg A‐GPC

83.4 ± 14.7

0.64

250 mg A‐GPC

80.2 ± 8.8

200 mg Caffeine

86.0 ± 21.2

Placebo

87.3 ± 10.9

Body Fat%

500 mg A‐GPC

15.3 ± 8.9

0.83

250 mg A‐GPC

14.7 ± 8.6

200 mg Caffeine

13.4 ± 9.1

Placebo

16.9 ± 7.5

VO2 Max (ml/kg*min)

500 mg A‐GPC

33.1 ± 6.3

0.51

250 mg A‐GPC

34.9 ± 6.2

200 mg Caffeine

36.5 ± 5.9

Placebo

30.6 ± 4.1

Procedures

Participant reported to the lab for the initial visit during the morning hours (0600-0700) after an overnight fast (minimum 8 h), had the experimental procedures explained to them and gave written consent to be part of the study. Afterwards height and weight was measured using a physicians triple beam balance and stadiometer. The participants had an assessment of maximum aerobic capacity via a COSMED CPET system (COSMED, Rome ITL) with integrated electronically braked cycle ergometer and body fat percentage via air displacement plethysmography (Bod Pod Gold Standard System, COSMED Rome, ITL). Following these assessments participants performed 3 baseline trials of a countermovement jump, isometric mid-thigh pull, upper body isometric test and a psychomotor vigilance test. The participants were then assigned to groups and given the first dose of the treatment with 237 ml of cool water (500 mg A-GPC, 250 mg A-GPC, 200 mg caffeine or placebo) and sat quietly in the lab for 120 min post consumption. At 60 min and 120 min post ingestion a blood sample was taken to quantify free choline and thyroid stimulating hormone (TSH). The participants were then given supplements to take for the next 6 days in the morning and were dismissed. On the seventh day the participants returned to the lab fasted having taken their last dose of supplement. The subject then repeated the performance and cognitive measures a second time as outlined above.

Supplements

The group treatments consisted of two capsules per day for the 7 days of the study. The rational for the number of days of supplementation was based on earlier research on A-GPC [11]. Chemi Nutra (Austin TX) supplied all capsule for the study. The A-GPC capsules (both 500 mg and 250 mg) were supplied with a certificate of analysis from an independent lab, verifying active content through Quantitative nuclear magnetic resonance (NMR). The Caffeine capsule content was verified by an independent lab using high performance liquid chromatography (HPLC). Placebo capsules consisted of microcrystalline cellulose.

Isometric testing and force plate counter movement jump

The isometric mid-thigh pull test (IMTP) is a well-validated strength measure [14] with reported correlations of 0.5-0.8 with actual competition performance. The test equipment consisted of an AMTI force plate (Advanced Materials Technologies Inc., Watertown MA USA) secured beneath a custom Rouge fitness weightlifting rack (Rogue Fitness Inc., Columbus OH USA). The participants were instructed to stand with the feet shoulder width apart above the force plate. The height of the bar was adjusted so that the participant was in a position where the torso was upright, the knees achieved between 120 and 130 degrees of extension (measured via a goniometer) and the arms were straight while holding the bar. The participants’ hands were secured to the bar via weightlifting hooks to remove the variance associated with grip strength. The participants were told to “drive straight up” and to pull as hard as they could against the bar until the force began to noticeably decline. The peak force was assessed in triplicate at a sampling rate of 2000 Hz using an AMTI Force Plate. The average of the three trials was used for subsequent analysis of variables of interest.

The upper body isometric test (UBIST) used in this study has previously been reported to be both reliable (ICC =0.9) and valid when examined against a 1 RM bench press (r = .92) [15]. The participants were positioned on three elevated platforms with the chest directly suspended over a load cell anchored into the concrete floor of the lab (iLoad Pro, Loadstar Sensors, Fremont CA USA). The load cell chosen has a capacity of greater than 5000 Newtons and a listed accuracy of 0.25% for the full scale of measurement. The participants were placed in a push-up style position, with the hands at 150% of biacromial width, and the elbows at 90 degrees of extension (measured via a goniometer). A thick, non-elastic strap was run over one shoulder and under the opposite shoulder and connected with metal rings to a chain that was tethered to the load cell. The participants were positioned so that no slack was apparent in the chain prior to initiation of data capture.

The participants were instructed to keep their backs flat, and push with their hands maximally until told to stop by the researcher. Prior to data capture the load cell was tared to ensure the weight of the load cell and apparatus were accounted for. The researcher started data collection and verbally instructed the participant to “push as hard as possible”. The load cell captured data (150 Hz) until force noticeable declined (drop of 50 N). The average of three trials was used for subsequent analysis of variables of interest. For the countermovement jump (CMJ) the participants were asked to perform three maximum effort jumps off an AMTI Force Plate (Advanced Materials Technologies Inc., Watertown MA USA). For this test the participant placed their hands on their hips, to remove the influence of the upper body. Data from the test was analyzed using a software package specific to CMJ analysis (Flo Inc., Westbrook, ME USA). The average of the three trials was used for subsequent analysis of variables of interest. Data from this study suggested high reliability with ICC values of greater than 0.8.

Cognitive testing

The Walter Reed palm-held psychomotor vigilance test (PVT) was administered to the participants after resting for at least 10 min in a quiet room. The PVT is a test of simple visual reaction time and was developed at the Walter Reed Army Institute of Research [16] and was used to assess mean reaction time over a 5-min time course. The test used random periods of time in which a target stimulus are displayed on the screen of a Palm handheld device. The program was set to display approximately 100 stimuli in the 300-s (5 min) period at randomly spaced intervals. This program computes a mean reaction time to each stimulus, as well as major and minor lapses in attention. This instrument has been used in large scale studies conducted by the military and is extensively represented as a reliable (test-retest >0.8) cognitive measure in the literature [16].

Serum free Choline and thyroid stimulating hormone

Blood was collected at 60 and 120 min post initial dose from a vein in the antecubital space into serum separator tubes. The blood was allowed to clot at room temperature and then a clinical centrifuge was used to separate the serum, which was aliquoted and stored at −35 degrees Celsius. At the conclusion of data collection serum aliquots were thawed and free choline levels were determined via a colorimetric assay (BioVision Inc., Milpitas CA USA) read at 450 nm on a microplate reader (ELx 808, Bioteck Winooski VT USA). Similarly, serum TSH was determined by a commercial ELISA kit (Eagle BioScience, Nashua, NH USA).

Statistical analysis

Differences in baseline performance were assessed via ANOVA. Changes from average baseline performance for IMTP and UBIST were assessed by group via ANOVA. Serum free choline and TSH levels were analyzed via repeated measures ANOVA. Changes in CMJ variable were analyzed via ANCOVA with body mass as a covariate. PVT performance on day seven was examined via ANOVA by group. All statistical analyses were performed using a modern statistical software package JMP 12.0 (SAS Institute Inc. Cary NC USA). Statistical significance was set a priori at p < 0.05.