Interest in exercise induced growth hormone has significantly increased due to its emergent usefulness in the development, recovery, and conditioning of muscle fibers.1 A largely effective method of increasing EIGH is seen in highly intense, short-burst exercises as well as by the ingestion of a specific post-exercise macromolecular ratio.2 It is well known that GH is a vital hormone that is key for physical strength, health and longevity.1 Along with the proper exercise, there is a proper synergy window after exercise that food must be ingested. In order to optimize EIGH production, and to facilitate the rate at which amino acids can mobilize muscle tissue, it is crucial to abide by a certain ratio of carbohydrates to proteins for post exercise food intake.2,3
The widely accepted ratio for post-exercise carbohydrates to proteins will be expounded upon in this paper. Then, this ratio will be tied into how it relates to fitness professional Phil Campbell’s Peak 8 program. Campbell’s program, along with the proper post-exercise food, concurrently enhance the production of EIGH.1 The Peak 8 protocol includes both aerobic and anaerobic exercises in such a way that EIGH production is optimized. With this optimization, research shows that anaerobic exercise and post-exercise food ingestion are the underpinnings of EIGH production.2,3 Knowing about the activity of EIGH is essential for athletes who are seeking to recover quicker and increase muscle and bone density while also decreasing adipose mass. The specific processes of the Peak 8 program, as well as a discussion of the importance of GH in muscle building and fat loss will be elaborated in this paper.
II. Growth Hormone Rebuilds Muscle and Bone Tissue While Also Decreasing Fat
The significance of GH is well known for its role in the developmental process with how it makes an individual grow tall.1 Furthermore, recent research indicates that the power of EIGH is also shown in its ability to rebuild muscle tissue, bone tissue, as well as stimulate the process of lipolysis.2,3,5 There are two ways that EIGH can naturally be increased to produce vast physiological health benefits. These two modes of EIGH increase can be found in combined aerobic and anaerobic exercise, as well as proper food ingestion after exercise.2
III. Types of Exercise Proven to Increase EIGH
The research is clear that short burst, high intensity exercise can be used to increase baseline GH levels by as much as 530%.1 Moreover, this type of exercise needs to involve all three energy systems of the body, giving the heart both an anaerobic and aerobic workout, and thereby involving all three muscle fiber types. Among the literature, the most successful program was created by Phil Campbell, and is named Peak 8 because of the 8 intense, 30 second bursts that it involves. The Peak 8 protocol consists of the following: (1) 3 minute warm-up, (2) 30 second sprint, (3) 90 second recovery, (4) Repeat 7 times, and (5) Cool down for 3-5 minutes at a 50% RPE. This is not an easy program, and it is meant to be completely exhausting by the 8th sprint. It should be noted that this program is designed for moderately fit to elite individuals, and is not advised for obese or highly untrained individuals.2,3
This seems to be the general pattern with studies on EIGH within the literature: the protocol is designed for fit individuals and mostly fit individuals are the only group to be studied. However, a modification of the protocol can be made in order to accommodate untrained athletes. This can be done by decreasing the amount of sprints from 8 to 2 for the most severe cases. More research needs to be done on un-trained individuals before the production of EIGH can be widely ascertained among all demographics.
IV. Why Peak 8 Increases EIGH
The program’s effectiveness is seen in the way it utilizes the anaerobic process during the sprint and the aerobic process during the recovery. It should also be noted that the recovery is supposed to be performed at 50-60% maximal effort. In a study done by Phil Campbell, at half of maximal exertion, the resting heart rate for a 56 year old male in the aerobic recovery phase shows the resting heart rate to be 145 bpm on his 5th sprint.4 This heart rate is similarly achieved when on a long distance run at one speed for a long duration.2 In this sense, there is a cardio portion of the protocol that one gets from the 3:1 rest to work ratio. At times, the subject’s heart rate rose to his max Karvonen’s upper limit threshold, indicating that he was just below his second anaerobic threshold. Research shows that training just below your second anaerobic threshold is optimal for buffering lactic acid in subsequent exercise, and is a major benefit to athletic performance.7,10 Since athletic performance and the ability to produce EIGH are directly related, Peak 8 exercise once again shows its effectiveness.
V. The Three Energy Systems At Work
During the subject’s Peak 8 workout, the ATP-PCr system is used in the first 6-8 seconds of the sprint; then the Glycolitic System is used in the next 22-24 seconds of the sprint, while the aerobic system is used during the active recovery. The use of all three energy systems is critical for increased production of EIGH at the pituitary, and is what makes the Peak 8 program so effective.1 Studies done by Godfrey et al. augment to this by concluding that humans will produce large amounts of EIGH only if lactate has accumulated in the bloodstream.9 The Peak 8 program is designed to push the individual to the brim of the onset of lactate accumulation, which according to Godfrey is indicative of high EIGH production.9 The other mode by which the Peak 8 program proves its effectiveness is by means of post-exercise food intake of a 4:1 ratio of carbohydrates to proteins.
VI. Nutrition After Exercise Can Increase or Inhibit EIGH Production
Research shows that EIGH is secreted at the pituitary up to two hours after exercise.2,3 Taking advantage of this 2 hour window is essential for optimal EIGH production. Optimally, one can take full advantage of this synergy window by consuming a 4:1 ratio of carbohydrates to proteins within 15-30 minutes of a combined anaerobic and aerobic workout.1 However, it is crucial to ingest the right type of carbohydrates and proteins, paying closer attention to the carbohydrates due to their effect on insulin levels.
The critical aspect that determines the production or inhibition of EIGH after exercise is seen by an individual’s insulin resistance.3,4,5 Most researchers now agree that the lower an individual’s levels of insulin after exercise, the more prolific the individual will be in producing EIGH. A recent study in the Journal Of Applied Physiology found that eating a low-carbohydrate meal after combined anaerobic and aerobic exercise enhances insulin sensitivity.8 This is highly beneficial, since impaired insulin sensitivity, or insulin resistance, is the underlying cause of type two diabetes, and a significant risk factor for other chronic diseases, such as heart disease.2
The commonly accepted post workout macromolecular ratio is 4 parts carbohydrates to 1 part protein.1,3,4 A recommended minimum of 20-25g of protein is needed to experience an increase in EIGH.4 The ratio of 4:1 is optimal for EIGH production but only from certain carbohydrates and protein sources. Moreover, the exact food cannot be suggested because of the variability of insulin resistance. Depending on how an individual produces insulin in their body immensely effects the production of EIGH.5 Insulin sensitivity is highly variable, and is therefore hard to measure without a blood test.
VII. The Inevitable Slowing Of Growth Hormone Production
A common misconception is that the slowing of metabolic rate with age is the only reason for the resistance of fat burning and muscle building. Recently within the scientific literature, there have been widespread consistencies pointing to an event called somatopause.2,5 When breaking up somatopause into its two roots, it is articulated “somatotropin” and “pause.” Somatotropin is a broad term that describes human growth hormone, and somatopause could literally be called “growth hormone pause.” Research shows that somatopause is tied directly to the way the body decreases the amount of growth hormone at the end of development or around the age of 32 or 33. Increasing baseline GH is essential to combat Somatopause and maintain athletic performance for middle-aged people.2
VIII. Review of Strengths and Weaknesses of The Selected Literature
The studies and articles that were used for this paper have advantages and disadvantages for supporting claims concerning EIGH. The articles by Mercola are meta-analysis articles that are comprised of multiple peer-reviewed journals. Even though the articles are written for the general public, they are still a valid source of collective literature. However, it is important to not that they do not hold the same credibility as a peer-reviewed journal. Mercola is an osteopathic physician and has excellent reliability and discretion of legitimate studies, which is why his information is included in this paper. Also, Mercola had the pleasure of interviewing Phil Campbell, the creator of the Peak 8 program. A lot of the information included in this paper was taken from video seminars and articles posted by Dr. Mercola that involved Phil Campbell, giving a more interactive summary his studies.
The study included by Rudman et al. is a highly cited study within sports and exercise science literature, showing its validity concerning somatopause, and its usefulness among health related topics. Its frequency in the literature is most likely due to its age, which is also a minor weakness. However, it is one of few studies available that studied how exercise can produce growth hormone to combat somatopause. More studies need to be done before growth hormone as a somatopause combatant can be ascertained.
The study by Newson et al. was endorsed by Phil Campbell and is highly applicable to the Peak 8 workout. It is well cited amongst scientific literature and is generally well accepted. The protocol for this study was extensive and thorough, however it would have been more widely applicable if they included women, and untrained athletes within their sample. Moreover, the sample size for this study included only 9 fit men. The strength of this study would have been increased if the sample size were representative of a wider demographic. Overall, this study clearly concluded that eating a low glycemic diet after workouts increases insulin sensitivity among well-trained men. More studies need to be done before one can predict that insulin sensitivity will behave similarly for a more representative sample.
The study by Wasserman is a highly cited study among the sports medicine literature and is considered to be the foundation of anaerobic related studies. It should also be noted that although its conclusion regarding lactate buffering is well known, the study dates back to over 20 years ago. Also, only the abstract is available online, which makes assessment of this study to be limited to what is shown in the conclusion. Wasserman’s conclusion states that reaching the lactate threshold is important for lactate buffering in subsequent exercise bouts, and this is well known and cited frequently. The validity of his study is promising due to its high frequency within sports medical literature.
The study by Armanini is highly specific and uses detailed protocol that involves blood monitoring, hydrostatic weighing, and even psychological quantitative analysis. Although this study used rigorous measures to conclude that the blood of Olympic athletes is highly concentrated with growth hormone, it failed to examine a representative sample. In fact, this study only examined one female individual’s growth hormone levels. Female growth hormone levels have not been diligently studied in the sports and exercise science world in comparison to male growth hormone levels. However, it is compelling after combined anaerobic and aerobic exercise that a female would respond to growth hormone in a similar way to the widely studied fit male.
Overall, there is compelling research that claims short burst, high intensity exercise as well as proper post-workout food intake can dramatically increase the production of EIGH. Growth hormone is highly effective in muscle and bone tissue repair, as well as inducing lipolysis, and is therefore an essential tool for those who exercise. Due to virtually all studies inclusion of only fit individuals within the sample, more studies need to be performed before recommendations can be made for women and untrained people regarding EIGH.
There have been numerous studies administered on fit, mostly male individuals that clearly conclude EIGH levels rise with: (1) a high taxation of all three energy systems, (2) a high taxation of all three muscle fibers, and (3) a low-glycemic post-workout consumption ratio of 4 parts carbohydrates to 1 part proteins. If each of the aforesaid criteria have been met, research shows that baseline GH will increase for fit males, however, more studies need to be done on females and un-trained subjects before anything can be widely ascertained.1,8,9