Tag Archives: resistance exercise

Is Growth Hormone Really an Anti-Aging Supplement?

Insight 17 – Despite considerable evidence to the contrary, human growth hormone maintains a reputation as a valid anti-aging therapy.  There exists a wealth of over-the-counter supplements claiming to elevate growth hormone levels and restore youthful vigor.  Unfortunately, claims of rejuvenation are exaggerated and associated adverse effects are played down.  This blog will discuss these issues and define alternative ways to stay healthy without human growth hormone supplements. 

Introduction

Growth hormone is one of many hormones produced by the pituitary gland, a small endocrine organ located at the base of the brain.  As aptly named, growth hormone plays a major role in the growth of an individual from birth to puberty and young adulthood.  However, growth hormone cannot take all the credit for influencing our growth.  It stimulates production of a liver hormone, insulin growth factor-1 (IGF-1), and the two partner together to exert biological influence. 

Changes in Growth Hormone with Age

Blood levels of growth hormone peak at puberty and decline about 80% by age 55 (as does IGF-1).  Along a similar timeline, muscle and bone mass peak in young adulthood and slowly decline with age roughly correlating with a fall in circulating growth hormone.  Since growth hormone and IGF-1 are significant effectors of muscle and bone health and since their levels fall with age, scientists reasoned that restoration of growth hormone to youthful levels (by infusion or injection) would reverse age changes in muscles and bones.  Hence, growth hormone should provide the desired rejuvenation.

Can Growth Hormone Rejuvenate the Aging Body?

Using the newly available synthetic growth hormone, a small study of 21 men (61-81 years of age) measured lean body mass (roughly muscle mass), fat mass, skin thickness and bone density before and after 6 months of daily injection of growth hormone (Rudman et al., 1990).  In 12 elderly men receiving growth hormone, muscle mass (8.8%)  and  bone density (1.6 %) increased, skin thickness increased (7.1%) and fat mass decreased (14.4%) compared to controls.  In 1990, these remarkable and significant findings supported the concept that growth hormone had rejuvenating powers.

The Negative Side of Growth Hormone

Sadly, this study and related hype raised appropriate skepticism.  Firstly, the study by Rudman et al., (1990) was too small for fundamental generalizations.  Additionally, treatment-associated negative effects such as an elevation in systolic blood pressure and fasting glucose levels in those receiving growth hormone, took a back seat.  Secondly, a review of 18 clinical trials (Liu et al., 2007) with growth hormone injections in men for up to 27 weeks, confirmed the earlier findings but emphasized that the extent of changes in body composition was very modest.  

Importantly, the small positive changes were outweighed by serious adverse effects. These adverse effects included:  a)  soft tissue swelling (edema); b)  joint stiffness (arthralgias); c) carpal tunnel syndrome (nerve compression due to fluid retention causing hand and finger pain); d)  enlargement of male breasts (gynecomastia) and e)  impaired fasting glucose (risk factor for diabetes mellitus).

Thirdly, despite the increase in muscle mass, there was no comparable increase in muscle strength.  This is exceedingly important because age-related loss of muscle strength (not muscle mass) leads to loss of physical independence.  Therefore, despite youthful levels of growth hormone, the beneficial effects in the elderly are too minor to warrant multiple serious adverse effects with no gain in muscle strength. 

Can Growth Hormone Accelerate Aging?

There is a wealth of evidence gathered from animal studies that a deficiency of growth hormone, whether artificial (genetic manipulation) or natural (hereditary) slows many aspects of aging and increases longevity.  On the one hand, growth hormone deficient animals exhibit small size, delayed puberty and reduced fertility.  On the other hand, these animals live longer than controls with normal growth hormone levels.  This is because many anti-aging activities such as increased resistance to stress and decline in pro-inflammatory mediators are enhanced when growth hormone is scarce.  Together these activities and many more, support a longer lifespan with lower levels of growth hormone.   

Growth Hormone Effects (injection/infusion)

Genetic disorders of growth hormone deficiency in humans exhibit similar changes.  These individuals exhibit a resistance to major diseases and although they do not have exceptional longevity, it appears that they enjoy a longer health span.  Taken together these findings suggest that growth hormone therapy for the healthy elderly has a significant potential to accelerate age changes.

An Alternative Approach Without Growth Hormone

As noted above, growth hormone use does not make muscles stronger.  Therefore, as discussed in (Insight  3, Progressive Resistance Exercise) a proven way to increase muscle strength is engagement in a serious program of resistance exercise, e.g. hand held weights or machines.  A program of progressive resistance exercises of increasing difficulty at home or in the gym will maintain muscle strength.  Optimal muscle strength ensures continued independence. Specifically, this is independence to carry out daily activities e.g. shopping, walking, housework. This leads to a better quality of life.  Additionally, progressive resistance exercise preserves balance and prevents falls

The Marketing of Growth Hormone Supplements

Growth hormone medications exist in many forms, all approved by the FDA.  Physicians prescribe them to treat well-defined endocrine deficiencies, affecting patients of all ages.  In contrast, the healthy elderly rely on advertisements of growth hormone supplements.  Websites claim that supplements, called secretagogues, boost blood levels of growth hormone.  Secretagogues are mixtures of select amino acids. 

Thus far, only one company tested their proprietary secretagogue mixture in human trials (2 clinical trials; 16 volunteers each).  Growth hormone levels rose significantly after a single oral dose of their secretagogue.  This information is worthwhile but it is extremely limited. 

Firstly, consider there are no clinical data at all for the many growth hormone secretagogues on the market.  Secondly, the two small trials mentioned above require confirmation by a larger number of volunteers, preferably with different doses and longer duration of use (not just 2 hours).  Thirdly, there are no data on the assumed positive effects of these supplements on energy output, muscle repair, and anti-aging potential.  Furthermore, there are no data on the negative adverse effects of these supplements.  

As stated above and reviewed by others (Bartke et al., 2021;Colon et al., 2019), the adverse effects of clinically tested growth hormone injections in the elderly outweigh the small effects on muscle, bone and fat mass.  Until evidence exists to the contrary, secretagogues that raise levels of growth hormone are expected to exhibit the same results.  Until more thorough trials are done, the best way to improve muscle mass and strength and decrease fat mass is with resistance and aerobic exercises.

Summary

Growth hormone fails as a hormone of rejuvenation.  In fact, extensive data in animals and some observations in humans suggest that growth hormone accelerates aging.  Clearly, for the healthy elderly, the multiple severe risks of growth hormone use far outweigh the small changes in muscle, bone and fat mass.  There is a safer way to build both muscle mass and strength.  It is an engagement in a progressive resistance exercise program either at home or at the gym. 

References (Complete reference list on request) articles on http://pubmed

Bartke A , Hascup E , Hascup K, Masternak MM. Growth Hormone and Aging: New Findings. World  J Mens Health. 39:   454-465, 2021

Liu et al., Systematic review: the safety and efficacy of growth hormone in the healthy elderly Ann Intern Med.146:  104-15, 2007.

Rudman D. et al., Effects of Human Growth Hormone in Men over 60 Years Old.  N Engl J Med. 323:  1-6, 1990.

Insight 3: Ways to retard skeletal muscle aging

Regular Progressive Resistance Training is the answer

So what can the older adult do to assure continued independence, normal weight and avoid a fall and Type 2 Diabetes?  Results of over hundreds of clinical trials conclude that regular progressive resistance training (PRT) is the answer.  This is the way the to retard skeletal muscle aging. Although this strategy has been in the scientific literature for near 30 years, surprisingly and sadly, very few adults follow an exercise program that includes resistance exercises (in the US population, an estimated 5% participate in resistance exercise versus more than 50% that engage in an aerobic regimen e.g. walking, swimming, jogging).  An additional piece of advice, stemming directly from clinical trial results, recommends the ingestion of 20-35 grams of quality protein post PRT workout to maximize the benefit gained from the resistance training alone. 

Progressive resistance training to retard skeletal muscle aging?

So what exactly is progressive resistance training (PRT)?  Simply, it is strength and speed training against a resistance which is either free weights e.g. dumbbells or barbells, weight machines (gravity resistance), calisthenics e.g. squats (body and gravity resistance) and/or use of resistance elastic bands or tubes.   In starting a program of PRT, consideration is given not only to the  type of resistance as just indicated but also, target muscles, frequency of exercise, intensity, and repetitions. 

Liu and Latham (2015)* reviewed 121 clinical trials with over 6,000 participants and concluded  that ” Doing PRT two to three times a week can improve physical function in older adults, including reducing physical disability, some functional limitations (i.e. balance, gait speed, timed walk, timed ‘up-and-go’, chair rise; and climbing stairs) and muscle weakness in older people.”  The average age in these studies ranged from 61 to 88 years.   Approximately half of the studies enrolled healthy sedentary older adults; the remainder were comprised of older adults with physical disabilities or limitations.   PRT lasted anywhere from 10 weeks to 2 years, targeting different muscle groups with increasing intensity.   It is noteworthy that older adults of any age, with or without physical limitations, will benefit from PRT.

A reasonable progressive resistance training program

What is an example of a successful PRT program?  A reasonable PRT program, based on results of interventional studies discussed above, has been developed for beginners, intermediate and advanced participants (Law et al., 2016)*.  The program is given below (PDF 1).  Target muscles are those of the chest, back, arms, shoulder, upper legs and lower legs.  For beginners, the program is 8 weeks in duration, twice weekly. Phase 1 (2 weeks) requires exercises at an intensity of 50-60% of one maximal repetition (RM) with performance of one exercise set with 12-15 repetitions.  For weeks 3-8,  the intensity increases to 60-69% of 1RM, the repetitions increase to 18, and a new exercise set is added. 

Ideally start with weight machines and trainer

Law et al., (2016) favors starting with weight machines and ideally a trainer to assure that the correct form is achieved for each exercise.  It is also advisable to discuss a new exercise program with your physician before setting forth.  The sample program for intermediate and advanced PRT modifies the beginner program and adds new exercises with increases in both intensity, sets and repetitions.  In lieu of weight machines, there are reliable established  free videos on strength training with dumbbells (PDF 2), and alternative exercises e.g. calisthenics and elastic bands (PDF 3)).  Remember the program must be progressive to be of benefit and hence must increase in intensity over time.

Progressive resistance training and protein supplementation are proven means to minimized age-associated sarcopenia and dynapenia.

To maximize the benefits of PRT, findings from numerous studies, albeit with a small number of volunteers, show that consumption of high quality protein e.g. soy or whey (20-35 gm) or essential amino acids leucine and isoleucine (3.5 gm) stimulates skeletal muscle formation and leads to better outcomes (mass, strength, performance) than PRT without protein supplementation.  Leucine and isoleucine cannot be synthesized by the body so both must be ingested. Leucine and isoleucine are the amino acids most adept at encouraging exercised muscles to up their production of major muscle proteins e.g. myosin.  Protein supplementation is based on studies with volunteers, 55-85 years of age, of various weights (normal to obese) who performed resistance exercises  (hand held weights and machines) for 10-26 weeks, 2-3 x per week, multiple target muscles with 3 sets of 8-12 repetitions at 70-85% maximal repetition.  

Do not forget protein supplementation

PRT plus protein supplementation is the anti-aging strategy that is definitely in sync with living a longer healthier life.  Consider the wealth of benefits from this strategy:  strength to perform all desired daily activities, avoidance of physical disabilities, maintenance of ideal weight or weight reduction, adequate handling of sugars/carbohydrates, avoidance of falls and an acceptable response to the cold.  These are advantages that guarantee continued independence and optimal quality of life.  These are benefits that should motivate every adult over 50 to participate in this strategy. 

Progressive resistance training is part of 4-prong exercise program for the older adult

PRT is one part of a 4-prong exercise program validated to minimize age changes.  PRT is of high priority considering the plethora of positive outcomes for the older adult.  However, the three other components (aerobics, balance and stretch ) of the 4-prong exercise program provide different but equally important advantages and will be discussed in my next blog.

Resistance exercise with machines

PDF 1 (Resistance exercises with machines) describes evidenced-based PRT proposed by Law et al., (2016)**   It consists primarily of exercises using machines one would find in a fitness gym or YMCA.  There are three progressive levels, beginner, intermediate and advanced that progress the individual from 1 set of 12 repetitions to 3 sets of 10 repetition over a period of 32 weeks.  Machine-dependent exercises is probably the easiest way to initiate PRT but this approach does require a gym membership.  The main advantage is that experienced personnel are available to assist with the use of each machine.  To provide a level of familiarization, PDF 1 also contains videos that demonstrate the proper execution of each exercise with the particular machine. 

Resistance exercises with dumbbells

PDF  2 (Resistance exercises with dumbbells) follows the progression of strength training defined by Law et al., in PDF 1 but substitutes dumbbells (hand held weights).   The advantage of these exercises is that they can be done at home.  However, one must purchase a set of dumbbells.  I have added videos for all of these exercises since it is essential that they be performed exactly as described to gain the most benefit and avoid injury.

Alternative workouts

PDF 3 (Alternative workouts) list 7 different workouts ranging in time and difficulty, available on line that one may also follow and that can be performed at home.  Although none per se have been subjected to a clinical trial they contain exercises providing benefits comparable to those defined in PDF 1 and 2.  The key point to remember is that resistance exercise needs to be progressive.  Thus either increase in weight or resistance and/or number of repetitions is required to yield strength benefit.

*  Liu C-J, Latham NK.  Progressive resistance strength training for improving physical function in older adults.  Cochran Database Syst Rev: July 8 (3): CD002759, 2009.

** Law TD, Clark LA, Clark BC.  Resistance exercise to prevent and manage sarcopenia and dynapenia. Annu Rev Gerntol Geriatr 36: 205-228, 2016.