Why 8,000 mg of L-Citrulline Malate?
NorthStar Nutrition’s PR Pre-Workout contains 8,000 mg of L-Citrulline Malate (or simply, citrulline malate) because of the extensive amount of robust evidence supporting the effectiveness of this exact dosage. Many of our competitors’ formulas also contain citrulline malate, but with inadequate doses to unlock the full spectrum of its potential benefits. The studies outlined below provide compelling evidence of citrulline malate’s advantages in terms of:
Enhancing Muscular Endurance
Amplifying Strength and Power Output
Reducing Perceived Effort
Diminishing Muscle Soreness
Accelerating Recovery
Key Studies
The European Journal of Applied Physiology, in a comprehensive meta-analysis, determined that to achieve notable improvements in muscular endurance (measured as repetitions until failure) with citrulline malate, individuals should aim to consume a dosage of 8,000 mg.
A randomized, double-blind, 2-period crossover design study published in the Journal of Strength and Conditioning Research investigated the effects of a single dose (8g) of citrulline malate (CM) on the performance of flat barbell bench presses as an anaerobic exercise and its impact on reducing muscle soreness after exercise. 41 males participated.
Protocol
Participants performed two consecutive pectoral training sessions (16 sets) in a randomly assigned order. In one of these training sessions, the participants were given 8 grams of CM, while a placebo was administered in the other session.
Key Findings
- Performance Enhancement: The study revealed a significant improvement in exercise performance. The number of repetitions during flat barbell bench presses increased notably when participants consumed the 8-gram dose of CM, with the most prominent improvements observed from the third set onwards.
- Muscle Soreness Reduction: Notably, there was a substantial 40% decrease in muscle soreness experienced at 24 and 48 hours after the pectoral training session when CM was administered.
- Universal Effectiveness: Importantly, over 90% of the participants experienced positive effects from CM supplementation, making it a highly effective aid for athletes.
This randomized, double-blind, counterbalanced study, also published in the Journal of Strength and Conditioning Research, assessed the effects of citrulline malate supplementation on exercise performance, blood lactate levels, heart rate, and blood pressure during lower-body dynamic resistance exercise. 12 advanced resistance-trained males participated.
Protocol
Subjects were divided into two groups, one receiving a placebo (PL) and the other citrulline malate (8 grams). Participants then engaged in a series of lower-body resistance exercises, including the leg press, hack squat, and leg extension machines. They performed five sequential sets at 60% of their one-repetition maximum (1RM) for each exercise until failure.
Key Findings
- Performance Improvement: The group taking citrulline malate performed significantly more repetitions in all three exercises compared to the placebo group.
This randomized, counterbalanced, double-blind study, published in the Journal of Dietary Supplements, investigated the impact of citrulline-malate (CM) supplementation on repeated bouts of resistance exercise. 14 resistance-trained males participated.
Protocol
The participants were randomly assigned to two groups: one receiving a placebo (PL) and the other CM (8 grams). The participants performed three sets of three exercises to failure: chin-ups, reverse chin-ups, and push-ups.
Key Findings
- Taking CM enhanced participants’ performance by helping them do more reps in their workouts.
- Chin-ups: CM group did an average of 32.2 reps compared to 28.4 in the placebo group (a noticeable increase).
- Reverse chin-ups: CM group averaged 32.1 reps, compared to 26.6 in the placebo group (again, a clear improvement).
- Push-ups: CM group averaged 97.7 reps compared to 89.1 in the placebo group (a significant increase).
This randomized, double-blind, placebo-controlled study, published in the European Journal of Nutrition, assessed the effects of acute citrulline malate (CM) supplementation on the performance of upper- and lower-body weightlifting exercises in resistance-trained females. Given physiological differences between genders, this research focused specifically on how CM impacts female athletes. 15 females, with an average age of 23 years participated.
Protocol
Participants were randomly assigned to two groups, one receiving CM (8 grams dextrose + 8 grams CM) and the other a placebo (8 grams dextrose).
An hour after taking their assigned supplement, the participants engaged in weightlifting exercises.
Key Findings
- Improved Exercise Performance: CM supplementation led to significantly more repetitions in both upper- and lower-body exercises.
- Upper-body (bench press): The CM group did an average of 34.1 reps compared to 32.9 reps with the placebo group.
- Lower-body (leg press): The CM group resulted in an average of 66.7 reps, while the placebo group averaged 55.13 reps.
- Reduced Perceived Effort: When participants consumed CM, their rating of perceived exertion (RPE) during upper-body exercises was significantly lower compared to when they took the placebo (RPE of 7.9 vs. 8.6, respectively).
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Why 4,000 mg of CarnoSyn® beta-alanine?
NorthStar Nutrition’s PR Pre-Workout contains 8,000 mg of L-Citrulline Malate (or simply, citrulline malate) because of the extensive amount of robust evidence supporting the effectiveness of this exact dosage. Many of our competitors’ formulas also contain citrulline malate, but with inadequate doses to unlock the full spectrum of its potential benefits. The studies outlined below provide compelling evidence of citrulline malate’s advantages in terms of:
Enhancing Muscular Endurance
Amplifying Strength and Power Output
Reducing Perceived Effort
Diminishing Muscle Soreness
Accelerating Recovery
Key Studies
The International Society of Sports Nutrition International Society’s extensive meta-analysis firmly supports daily supplementation of beta-alanine within the range of 4-6 grams for a minimum of four weeks. This regimen has been shown to significantly increase muscle carnosine levels, acting as an intracellular pH buffer. This practice consistently enhances exercise performance, particularly in activities lasting 1 to 4 minutes, and helps reduce neuromuscular fatigue.
Drawing from a comprehensive meta-analysis involving 15 studies and 360 participants, beta-alanine showed significant performance enhancement. The meta-analysis showed particular improvement in exercises lasting between one minute and four minutes in duration, resulting in an impressive average improvement of 2.85%. Notably, to unlock these advantages, athletes must accumulate a substantial 179-gram intake or “loading phase” of beta-alanine over time.
This double-blind, placebo-controlled study assessed the effectiveness of beta-alanine supplementation as an ergogenic aid in tests of anaerobic power output following an 8-week training regimen consisting of high-intensity interval, repeated sprint, and resistance training. 22 college wrestlers (average age 19.9 years) and 15 college football players (average age 18.6 years) participated.
Protocol
Participants were divided into two groups, one receiving 4 grams per day of beta-alanine and the other receiving a placebo in powdered capsule form.
Key Findings
- Performance Improvements: Participants taking beta-alanine showed more favorable results on all performance tests compared to those on the placebo. The football players in the supplement group, in particular, exhibited substantial improvements, with a 1.1-second decrease in 300-yard shuttle time (compared to 0.4 seconds for the placebo group) and a 3.0-second increase in flexed-arm hang time (compared to 0.39 seconds for the placebo group).
- Weight and Lean Mass Changes: The wrestlers, both in the placebo and supplement groups, lost weight (which was the intended goal, aligning with their weight bracket allowance). However, the supplement group increased lean mass by 1.1 pounds, whereas the placebo group lost 0.98 pounds of lean mass. On the other hand, both groups of football players gained weight, with the supplement group gaining an average of 2.1 pounds of lean mass compared to 1.1 pound for the placebo group.
- Training Regimen Effect: The study suggests that beta-alanine has the potential to enhance performance and promote the accumulation of lean mass in a relatively short period (8 weeks) among previously trained athletes. Additionally, the type and intensity of the training regimen may influence the degree of benefit from beta-alanine supplementation.
This study, published in Amino Acids, The Forum for Amino Acid, Peptide and Protein Research, aimed to explore the effects of 28 days of beta-alanine supplementation on various aspects of exercise performance in women. The study assessed CarnoSyn’s effect on participants’ physical working capacity at fatigue threshold (PWCFT), ventilatory threshold (VT), maximal oxygen consumption (VO2-MAX), and time-to-exhaustion (TTE) before and after the supplementation period. 22 women – with an average age of 27.4 years – participated.
Protocol
Participants were divided into two groups, one receiving beta-alanine and the other a placebo. The study lasted for 28 days, during which participants took their assigned supplement.
Key Findings
- Improved Endurance: The beta-alanine group showed significant improvements in several key measures:
- Ventilatory threshold (VT) increased by 13.9%.
- Physical working capacity at fatigue threshold (PWCFT) increased by 12.6%.
- Time-to-exhaustion (TTE) during maximal cycle ergometry performance increased by 2.5%.
This double-blind, placebo-controlled study explored the effects of 28 days of supplementation with beta-alanine (b-Ala) and creatine monohydrate (CrM) on the delay of neuromuscular fatigue in untrained men. Participants were randomly assigned to one of four groups: placebo (PLA), creatine monohydrate (CrM), beta-alanine (b-Ala), or a combination of beta-alanine and creatine monohydrate (CrBA). Supplements were taken multiple times per day for six consecutive days and then reduced to twice daily for the remainder of the study. The primary measure was the physical working capacity at neuromuscular fatigue threshold (PWC(FT)), assessed before and after supplementation. 51 untrained males with an average age of 24.5 years participated.
Protocol
Participants were divided into four groups, each receiving a different supplement regimen. The supplementation period lasted for 28 days, with varying dosages of beta-alanine and creatine monohydrate.
Key Finding
- Delay in Neuromuscular Fatigue: The groups receiving beta-alanine (b-Ala) and the combination of beta-alanine and creatine monohydrate (CrBA) showed significant improvements in the delay of neuromuscular fatigue, as indicated by higher PWC(FT) values compared to the placebo group (PLA).
This double-blind, placebo-controlled study explored how combining beta-alanine supplementation with high-intensity interval training (HIIT) impacts endurance performance and aerobic metabolism in college-aged men. Participants were assessed for various parameters related to endurance and aerobic capacity, including peak oxygen utilization (VO2peak), time to fatigue (VO2TTE), ventilatory threshold (VT), and total work done at 110% of their pre-training VO2peak (TWD). The study was double-blind, with participants randomly assigned to one of two groups: a placebo group (PL) or a beta-alanine group (BA). Both groups took their respective supplements for six weeks while participating in HIIT training. 46 college-aged men with an average age of 22.2 years participated.
Protocol
Participants were divided into two groups: one received a placebo, and the other received beta-alanine. Supplements were taken four times per day for the first 21 days (total of 6 g/day) and then reduced to two times per day (3 g/day) for the following 21 days. Participants engaged in six weeks of HIIT training, consisting of 5-6 bouts of cycling work to rest ratio (2:1).
Key Findings
- Positive Impact of HIIT: After three weeks of training, significant improvements were observed in key measures, including VO2peak, VO2TTE, and TWD. These improvements highlight the effectiveness of HIIT in enhancing aerobic capacity and endurance (p < 0.05).
- Additional Benefits with Beta-Alanine: Following the second three weeks of training, the beta-alanine group (BA) demonstrated significant increases in VO2peak, VO2TTE, TWD, and lean body mass, which were not observed in the placebo group (PL). This suggests that consistent beta-alanine supplementation may enhance the benefits of HIIT, particularly in improving endurance performance and lean body mass.
This double-blind, placebo-controlled study explored the role of carnosine, a compound found in millimolar concentrations in human skeletal muscle, in the performance of highly trained rowers. The research investigated whether muscle carnosine content is related to performance and whether supplementation with beta-alanine, which increases muscle carnosine, can enhance performance in elite athletes. 18 Belgian elite rowers participated.
Protocol
Participants were divided into two groups: one received a placebo, and the other received beta-alanine supplementation at a dose of 5 grams per day over a period of 7 weeks.
Key Findings
- Correlation with Performance: There was a strong positive correlation between muscle carnosine content and rowing performance across various distances (100m, 500m, 2,000m, and 6,000m). This suggested that higher muscle carnosine levels were associated with better performance.
- Beta-Alanine Supplementation: After beta-alanine supplementation, muscle carnosine content increased significantly by 45.3% in the soleus muscle and 28.2% in the gastrocnemius muscle (muscles of the calf).
- Performance Enhancement: Following supplementation, the beta-alanine group improved their rowing performance by being 4.3 seconds faster in a 2,000-meter ergometer test compared to the placebo group. Before supplementation, the beta-alanine group was 0.3 seconds slower.
- Correlation with Performance Enhancement: The study found a positive correlation between the increase in muscle carnosine and the improvement in 2,000-meter rowing performance, suggesting that muscle carnosine content is a determinant of rowing performance.
This study investigated the impact of 30 days of beta-alanine supplementation (4.8 grams per day) on resistance exercise performance and hormonal changes. The study employed an acute resistance exercise protocol involving 6 sets of 12 repetitions of the squat exercise at 70% of one-repetition maximum (1-RM), with 1.5 minutes of rest between sets. Blood samples were collected at various time points before and after exercise to measure concentrations of growth hormone, testosterone, and cortisol. 8 experienced resistance-trained males participated.
Protocol
Participants were given beta-alanine (BA) or a placebo (PL) for 30 days at a dose of 4.8 grams per day.
Key Finding
- Improved Muscular Endurance: After 4 weeks of beta-alanine supplementation, there was a significant 22% difference in the total number of repetitions performed during resistance exercise between the beta-alanine (BA) and placebo (PL) groups (p < 0.05). Additionally, the mean power output was notably higher in the beta-alanine group.
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Why 3,000 mg of Betaine Anhydrouse?
NorthStar Nutrition’s PR Pre-Workout contains 3,000 mg of Betaine Anydrous because of the extensive amount of robust evidence supporting the effectiveness of this exact dosage. The studies outlined below provide compelling evidence of betaine’s advantages in terms of:
Increased Peak Power and Strength Output
Increased Training Volume
Optimized Body Composition
Decreased Cortisol Levels
Increased Muscle Oxygenation
Decreased Homocysteine Levels
Key Studies
This double-blind, randomized, crossover-designed study investigated the effects of betaine supplementation on cycling sprint performance. Male and female participants completed a series of sprint tests involving four 12-second efforts against a resistance equal to 5.5% of their body weight. The tests were conducted under various conditions: baseline, placebo, and betaine supplementation. The study included a total of 16 recreationally active subjects, both males and females.
Protocol
Participants underwent three sprint tests, with a 3-week washout period between tests two and three. For tests two and three, participants consumed either a placebo (carbohydrate-electrolyte beverage) or a beverage containing 0.42% betaine (approximately 2.5 grams of betaine per day). The betaine or placebo beverages were consumed daily, with half taken in the morning and half in the afternoon.
Key Findings
- Performance Improvements: Compared to baseline measurements, betaine supplementation resulted in significant increases in various sprint performance parameters, including average peak power (6.4%), maximum peak power (5.7%), average mean power (5.4%), and maximum mean power (4.4%).
- Betaine vs. Placebo: In comparison to the placebo group, the betaine-supplemented group also experienced significant enhancements in performance metrics, including average peak power (3.4%), maximum peak power (3.8%), average mean power (3.3%), and maximum mean power (3.5%).
- No Differences with Placebo: Notably, there were no significant differences between the placebo trials and the baseline measurements.
This randomized, double-blind, crossover-designed study investigated the ergogenic effects of betaine supplementation on strength and power performance. Participants completed two 14-day experimental trials, with a 14-day washout period in between, and underwent a standardized high-intensity strength/power resistance exercise challenge before and after 14 days of either betaine or placebo supplementation. The study included 12 men with an average age of 21 years and an average weight of 79.1 kg. Participants had a minimum of three months of resistance training experience.
Protocol
Participants were randomly assigned to receive either betaine or placebo supplementation for 14 days. The betaine group received 1.25 grams twice daily, for a total of 2.5 grams of betaine per day.
Key Findings
- Strength and Power Increases: Following 14 days of betaine supplementation, participants exhibited significant increases in various strength and power performance measures. These improvements were observed in bench throw power, isometric bench press force, vertical jump power, and isometric squat force during a standardized high-intensity resistance exercise challenge.
- Specific Performance Enhancements: Notably, betaine supplementation resulted in enhanced power, force, and maintenance of these measures in specific performance metrics, particularly in the smaller upper-body muscle groups.
This double-blind, placebo-controlled study evaluated the effectiveness of 15 days of betaine supplementation on muscle endurance, power performance, and the rate of fatigue in active college-aged men. The study included 24 male participants with an average age of 20-21 years.
Protocol
One group received daily betaine supplementation of 1.25 grams twice daily, for a total of 2.5 grams per day, while the other group received a placebo.
Key Findings
- Squat Exercise Endurance: The number of repetitions performed in the squat exercise was significantly greater in the betaine group compared to the placebo group at both 7 days and 14 days after supplementation.
- Quality of Squat Repetitions: The betaine group demonstrated a significantly higher number of repetitions performed at 90% or greater of peak power in the squat exercise at both 7 days and 14 days of supplementation compared to the placebo group.
This double-blind, randomized, placebo-controlled study investigated the impact of betaine supplementation on the bio-motor abilities of young professional soccer players during a competitive season. Participants were matched by position and randomly assigned to either a betaine group or a placebo group. The study involved 29 young professional soccer players with an average age of approximately 15.5 years.
Protocol
Participants in the betaine group received 2 grams of betaine per day, while those in the placebo group received a placebo, for a duration of 14 weeks. Various performance measures were assessed at three time points: pre-season (P1), mid-season (P2), and post-season (P3) over the course of 5 days each. Performance measures included muscular power, change of direction, acceleration, sprint performance, muscular strength, repeated sprint ability, and aerobic capacity.
Key Findings
- Muscular Strength and Power: The betaine group showed significant improvements in their 1-rep maximums during the mid-season and post-season measuring periods compared to the placebo group.
- Aerobic Capacity: The betaine group also had significant improvements in their VO2 max measurements in the mid-season and post-season measuring periods compared to the placebo.
- Sprint Performance and Peak Power: The betaine group showed meaningful improvements in their running-based anaerobic sprint test compared to the placebo group.
This double-blind, randomized, placebo-controlled study investigated the impact of consistent betaine supplementation on resistance training adaptation in young women, particularly in terms of body composition and muscular performance. The study included 23 young women with an average age of approximately 21 years who were new to structured resistance training.
Protocol
After one week of familiarization training, participants were matched for body composition and squat strength and randomly assigned to either a betaine (2.5 g/day) or placebo group. Both groups underwent resistance training for 8 weeks, consisting of three sets of 6-7 exercises per day performed to momentary muscular failure. Training sessions included two lower body and one upper body sessions per week on non-consecutive days.
Key Findings
- Changes in Body Composition: The betaine group showed significant improvements in lean mass (muscle gain), muscle thickness, and reductions in body fat percentage and fat mass.
- Training Volume: A trend was observed for greater weekly training volumes in the betaine group compared to the placebo group, providing evidence that supplementation increased participants’ capacity for higher training volumes.
This meta-analysis looked at the effects of taking betaine on markers related to heart health. Researchers reviewed studies published until February 2021. Here’s what they found:
- Elevated homocysteine levels have been associated with an increased risk of cardiovascular disease and cardiovascular events in several observational studies.
- Betaine supplementation had positive effects on markers like betaine levels, total cholesterol, low-density lipoprotein (LDL), homocysteine, dimethylglycine (DMG), and methionine.
- When they looked at different doses, they found that a lower dose of betaine (less than 4 grams per day) could lower homocysteine without affecting cholesterol levels.
In conclusion, this study suggests that taking a 3 gram dose of betaine is optimal for healthy individuals to help with heart health by reducing homocysteine levels without raising cholesterol.
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Why 1,500 mg of L-Tyrosine?
NorthStar Nutrition’s PR Pre Workout contains L-Tyrosine because of its proven ability to increase catcholamine levels depleted during stressful or challenging conditions. By doing so, L-Tyrosine alleviates stress-induced cognitive decline. The studies outlined below provide compelling evidence of L-Tyrosine’s advantages in terms of:
Increased Cognitive Performance
Increased Working Memory
Increased Attention
Reduction of Stress Signs and Symptoms
Reduction of Blood Pressure
Key Studies
This randomized, double-blind, placebo-controlled, crossover design study, published in the Brain Research Bulletin, aimed to shed light on how tyrosine influences cognitive function, stress response, and blood pressure regulation during demanding tasks. 16 participants, consisting of both genders, participated in this study, with an average age of 25.
Protocol
Participants were administered either 100 mg/kg of tyrosine or a placebo before undergoing stress-sensitive cognitive testing. These tests included tasks sensitive to stress levels, conducted under the exposure of a 90 dB noise stressor. Cognitive performance was assessed using tasks like digit span and stroop tests. Furthermore, blood pressure and heart rate were monitored throughout the testing.
Key Findings
- Tyrosine supplementation resulted in improved performance in cognitive tasks, particularly the digit span and stroop tests, showcasing an enhancement of 1 hour post-administration.
- Notably, participants displayed a reduction in diastolic blood pressure 15 minutes after tyrosine ingestion, while 1 hour after ingestion, diastolic blood pressure remained comparable to the placebo group.
Building on previous research, this double-blind, crossover trial explored how tyrosine ingestion influences working memory, arithmetic skills, and monitoring abilities during multitasking. The objective was to ascertain if tyrosine could sustain cognitive performance, particularly in situations where stress compromises task efficiency. 20 participants, including both male and female subjects, took part. Each participant received 150 mg/kg of tyrosine or a placebo 60 minutes before engaging in cognitive testing.
Protocol
The study comprised two task batteries: a Multiple Task battery and a Simple Task battery. The Multiple Task battery simultaneously assessed working memory, arithmetic skills, and visual and auditory monitoring. On the other hand, the Simple Task battery measured working memory and visual monitoring alone. Cognitive testing occurred 1 hour post-tyrosine or placebo ingestion.
Key Findings
- Tyrosine administration significantly enhanced working memory accuracy and reduced the frequency of list retrieval during the Multiple Task battery, showcasing its potential to sustain working memory when other cognitive demands are present.
- The tyrosine group demonstrated superior performance on the complex Sternberg memory task, emphasizing its positive influence on tasks of higher complexity compared to simple tasks.
This double-blind study investigated the effects of tyrosine, an amino acid known for its cognitive benefits, on task performance, mood, blood pressure, and norepinephrine metabolite (MHPG) levels in a group of 21 cadets during a demanding military combat training course. The objective was to ascertain if tyrosine supplementation could mitigate the impact of stress and fatigue on cognitive task performance. 21 men and women participated in this study.
Protocol
Participants were divided into two groups based on the type of drink they received. Cognitive assessments were performed both before the training and on the 6th day.
Key Findings
- The group supplied with the tyrosine-rich drink demonstrated enhanced performance on memory and tracking tasks compared to the carbohydrate-rich drink group, emphasizing the potential of tyrosine to boost cognitive task performance under stressful conditions.
- Tyrosine supplementation led to a significant decrease in systolic blood pressure, suggesting a potential role in managing physiological stress during demanding tasks.
- Overall, the findings suggest that tyrosine supplementation, particularly in high-stress and physically demanding operational circumstances, can reduce the adverse effects of stress and fatigue on cognitive task performance, highlighting its potential in such demanding environments.
This double-blind study aimed to assess the behavioral effects of tyrosine supplementation during an episode of prolonged nighttime work involving sleep deprivation, evaluating its potential to counteract performance decrements. 18 men and women underwent a rigorous assessment involving nine iterations of a performance task battery and mood scales, spanning approximately 13 hours.
Protocol
The study explored the potential of tyrosine supplementation in ameliorating performance decline induced by sleep deprivation during prolonged nighttime work. Subjects engaged in a battery of performance tasks and mood assessments over a 13-hour period, starting in the evening and concluding the next morning. Tyrosine or a placebo was administered six hours into the experiment, and performance metrics were evaluated.
Key Findings
- Tyrosine supplementation was linked to a significant improvement in performance on a psychomotor task, countering the usual decline observed under conditions of sleep loss.
- Moreover, tyrosine intake significantly reduced the probability of lapses during a high-event-rate vigilance task, indicating its potential to enhance sustained attention and vigilance during extended work hours.
- These performance-enhancing effects were notable for approximately 3 hours post-supplementation, demonstrating a temporal effectiveness of tyrosine in mitigating performance decrements induced by sleep deprivation.
This randomized, double-blind, placebo-controlled crossover study delved into the effects of tyrosine on mood, cognitive tasks, heart rate, and blood pressure in a cohort of 16 healthy young subjects, particularly under stress-inducing conditions. The objective was to ascertain the potential of tyrosine in enhancing cognitive function and modulating cardiovascular responses amidst stress. 16 healthy women and men were involved in this study, contributing to an exploration of tyrosine’s effects on mood, cognitive tasks, and cardiovascular parameters. Each participant underwent testing on two separate days, one after ingesting 100 mg/kg of tyrosine and the other after placebo, with the order randomized to avoid bias.
Protocol
The study rigorously assessed the impact of tyrosine on various facets of cognitive performance and cardiovascular metrics. Subjects were exposed to a stressor, a 90 dB noise, while engaging in stress-sensitive tasks. Two cognitive tasks were conducted an hour after medication ingestion, designed to be highly sensitive to stress levels. Heart rate, blood pressure, and mood assessments were conducted to comprehensively evaluate tyrosine’s effects.
Key Findings
- Tyrosine demonstrated a notable enhancement in performance on two cognitive tasks, specifically those highly responsive to stress, underscoring its potential in improving cognitive function even under challenging conditions.
- A reduction in diastolic blood pressure was observed 15 minutes post-tyrosine ingestion, highlighting a potential antihypertensive effect of tyrosine.
- These findings illuminate tyrosine’s potential in fostering stress-resilient cognitive performance and its intriguing influence on blood pressure dynamics, positioning it as a candidate for further investigations into stress modulation and cardiovascular health.
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Why 600 mg of Alpha GPC?
NorthStar Nutrition’s PR Pre Workout contains 600 mg of Alpha GPC (Alpha-glycerylphosphorylcholine) because of the extensive amount of robust evidence supporting the effectiveness of this exact dosage. To unlock the full spectrum of Alpha GPC’s mental and physical potential benefits, an intake of 600 mg is crucial. The studies outlined below provide compelling evidence of Alpha-GPC’s advantages in terms of:
Increased Cognitive Performance
Neuroprotective Abilities
Improved Neuromuscular Connection
Increased Power Output
Increased Human Growth Hormone
Key Studies
Alpha-GPC and caffeine are known to boost mental and physical performance. Alpha-GPC helps with learning and memory, while caffeine enhances focus and athleticism. However, this randomized, double-blind, placebo-controlled, crossover design study aimed to understand how Alpha-GPC and caffeine immediately affect mood, brain function, and physical performance. 20 participants (10 males, 10 females), with an average age of 22, took part in this study.
Protocol
They were given either 200 mg of Alpha-GPC (aGPC-L), 400 mg of Alpha-GPC (aGPC-H), 200 mg of caffeine (CA), or a placebo (PL). After 30 minutes, they underwent various tests, including mood assessment, a mental subtraction task, and tests for reaction time, hand-eye coordination, power, speed, and agility.
Key Findings
- Participants who took Alpha-GPC had significantly faster scores in the mental task compared to those who took caffeine (CA) or the placebo (PL). Their scores improved by 18.1% and 10.5%, respectively.
- Additionally, the aGPC-L group displayed significantly higher Vertical Jump Peak Power compared to the placebo group, with an 8.5% increase. The aGPC-H group also had enhanced power by 7.5%.
This double blind, placebo controlled, cross-over design study aimed to investigate whether six days of Alpha-GPC supplementation could increase isometric force production compared to a placebo. 13 college-aged males (with average characteristics including age, height, weight, VO2 max, and body fat percentage) participated.
Protocol
During an initial visit, participants familiarized themselves with isometric mid-thigh pulls and upper-body isometric tests. Baseline measurements were taken for both tests. Then, participants took either 600 mg of Alpha-GPC or a placebo daily for six days. After this period, they performed isometric mid-thigh pulls and the upper-body isometric test again. There was a one-week washout period before participants’ baselines were re-measured, and they crossed over to the other treatment.
Key Findings
- The Alpha-GPC treatment led to a significant increase in isometric mid-thigh pull peak force compared to baseline, while the placebo group experienced a decrease in force.
- For the upper-body test, the Alpha-GPC treatment trended towards increased force production compared to baseline.
Alpha-glycerylphosphorylcholine (A-GPC), an acetylcholine precursor, has shown potential in elevating growth hormone (GH) levels. This randomized, placebo-controlled, crossover study aimed to investigate the effects of a supplement primarily containing A-GPC on serum GH levels, explosive performance, and post-exercise substrate oxidation. 7 men, with an average age of 30.1 years participated. All participants had at least two years of resistance training experience.
Protocol
Participants were randomly assigned to ingest either 600 mg of A-GPC (as AlphaSize™) or a placebo 90 minutes before performing six sets of ten repetitions of Smith Machine squats at 70% of their pre-determined 1-repetition maximum. After the exercise, resting metabolic rate (RMR) and respiratory exchange ratio (RER) were measured using indirect calorimetry to assess post-exercise caloric expenditure and carbohydrate and fat oxidation. Following these measurements, participants performed three sets of bench press at 50% of their pre-determined 1-repetition maximum to assess peak force, peak power, and rate of force development. Serum samples were collected before exercise and at several time points up to 120 minutes post-exercise to measure hormone concentrations, including GH.
Key Findings
- Compared to the placebo, A-GPC led to a substantial 44-fold increase in peak GH levels.
- Peak bench press force was 14% greater in the A-GPC group compared to the placebo group.
- Additionally, trends suggested higher peak bench press power and lower post-exercise RER in the A-GPC trial.
This double-blind, randomized, crossover study aimed to investigate the immediate physiological responses to a single dose of Alpha-GPC. 8 healthy male subjects, with an average age of 25 years participated.
Protocol
In a randomized order, participants ingested either 1000 mg of GPC or a placebo. Fasting blood samples were collected before GPC administration (baseline) and at 60 and 120 minutes after ingestion. Subjects repeated the same protocol using the placebo.
Key Findings
After Alpha-GPC intake, there was a significant increase in plasma free choline levels at 60 and 120 minutes.
- Plasma growth hormone secretion significantly increased 60 minutes after GPC administration, while no significant changes were observed with the placebo.
- Furthermore, serum free fatty acid levels increased 120 minutes after GPC ingestion, whereas there were no changes with the placebo.
- Additionally, levels of serum acetoacetate and 3-hydroxybutyrate, indicators of hepatic fat oxidation, increased at 120 minutes after Alpha-GPC consumption, while the placebo had no effect.
This multicenter, double-blind, randomized, placebo-controlled trial aimed to evaluate the effectiveness and tolerability of the cholinergic precursor Alpha-GPC in managing cognitive impairment associated with mild to moderate Alzheimer’s disease. The study enrolled 261 patients, 132 in the Alpha-GPC group and 129 in the placebo group. The Alpha-GPC group had a mean age of 72.2 years, and the placebo group had a mean age of 71.7 years. The Alpha-GPC group consisted of 105 women and 27 men, while the placebo group included 94 women and 35 men.
Protocol
Individuals with mild to moderate Alzheimer’s dementia were administered either Alpha-GPC (400 mg capsules) or placebo capsules, three times daily, for 180 days. Various cognitive and behavioral assessments were conducted at the beginning of the study and after 90 and 180 days of treatment, including the Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Mini-Mental State Examination (MMSE), Global Deterioration Scale (GDS), Alzheimer’s Disease Assessment Scale-Behavioral Subscale (ADAS-Behav), all items of the Alzheimer’s Disease Assessment Scale (ADAS-Total), and the Clinical Global Impression (CGI) scale. The Global Improvement Scale (GIS) score was also assessed after 90 and 180 days of treatment.
Key Findings
- Patients treated with Alpha-GPC experienced a mean reduction in ADAS-Cog score of 2.42 points after 90 days and 3.20 points at the end of the 180-day study period. In contrast, the placebo group showed a mean increase in ADAS-Cog score of 0.36 points after 90 days and 2.90 points after 180 days of treatment.
- Other assessed parameters, including MMSE, GDS, ADAS-Behav, ADAS-Total, and CGI, consistently improved after 90 and 180 days in the Alpha-GPC group compared to baseline, while in the placebo group, they remained stable or worsened.
- Statistically significant differences were observed between the two groups after 90 and 180 days for ADAS-Cog, MMSE, GDS, ADAS-Total, and CGI scores. After 180 days, differences were also significant for ADAS-Behav and GIS scores.
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