Research
Research supporting Sláinte Health Solutions
Benefits Of Strength In Adolescents (12-17 years old)
History
In earlier decades, resistance training was often not recommended for children and
adolescents because it was assumed that, (i) they were too young to develop strength
because of insufficient testosterone, or, (ii) there was a high risk of damage to the
growth plates of their prepubescent bones.
However, as research in this field expanded, such assumptions were found to be
misplaced.
In fact, since those times, literally hundreds of studies and reviews have been published
confirming the safety and many benefits of resistance training in children and
adolescents.
Despite this evidence, surveys have reported only 1 in 5 adolescents meet the Healthy
People 2030 national recommendations for physical activity and muscle strengthening
activities.
Current and Ongoing Research
The American Academy of Pediatrics (AAP) has highlighted this situation – stating that
there is an urgent need for involving children and youth in some form of resistance
(strength) training, regardless of whether they are involved in sports.
They have published a research-based Policy Statement on “Resistance Training for
Children and Adolescents”.
Key Research Findings
Safety
Even today there is still a well-established belief that resistance training is unsafe and
harmful to the developing skeleton of children and adolescents. Because of this, some
teachers, parents, and caregivers, naturally concerned for the safety of their charges,
question if their children should lift weights in school- and/or community-based
programs.
However, after reviewing decades of research, the AAP has found no evidence to show
that participation in a well-designed resistance training program will stunt the growth of
children or harm their developing skeleton.
In fact, the opposite is the case!
Research has shown that childhood and adolescence seems to be the best time to
participate in strength-building because such activities encourage spontaneous physical
activity and enhance bone strength. With qualified supervision and a sensible
progression of training loads, regular participation in resistance training can favorably
influence growth and development in girls and boys.
To be clear, the AAP policy statement cites many research studies showing that
children and adolescents can safely participate in – and benefit from – resistance
training as long as such programs are well instructed/supervised with an emphasis on
correct technique.
In fact, all that research has actually flipped the safety focus on its head!
Informed teachers, educators and coaches today are more focused on the risk of
injury from lack of adequate strength to keep up with training and lifestyle demands.
In other words the concern has shifted from the dangers of children doing resistance training
to the dangers of children not doing resistance training!
Check out this additional confirmation article from the American College of Sports
Medicine entitled Mythbusting: Youth Resistance Training
Performance Benefits
Resistance training for children is not just about muscles! Research has revealed
additional sports related benefits such as improvement in motor skills, gains in speed
and power, reduced injury risk, and more effective injury rehabilitation. Such factors can
lead to improved sports performance but will also positively contribute to a healthy
lifestyle.
Health Benefits
Beyond strength increases and performance improvements, research has shown that
resistance training can also produce a wide range of health-related benefits in children.
These include improvements in cardiovascular fitness, body composition, bone mineral
density, blood lipid profiles, mental health and insulin sensitivity as well as increased
resistance to injury.
Lifestyle Benefits
The AAC has reported that participation in resistance training programs can help to
increase daily levels of spontaneous physical activity in school-aged children. Such
programs may (i) encourage overweight/obese children to become more physically
active and/or, (ii) be especially appropriate for those with lower levels of physical fitness,
poor exercise compliance, and/or reduced tolerance for aerobic training.
Take Home Message
An expansive and still growing body of research has found that resistance training is
safe, beneficial, and recommended for children and adolescents. It builds confidence
and strength for sports; helps increase daily physical activity; supports healthy bone
growth, and positively influences body development.
Benefits Of Strength In Adults (18-63 years old)
History
The importance of strength has been recognized for literally centuries – even for
regular, non-athletic adults. As early as 3600BC Chinese emperors actually required all
adult subjects to exercise daily, and military recruits were additionally required to pass
strength tests such as carrying heavy stones.
In more recent times, the fascination with strength could be found in the exploits of
circus and vaudeville strong men of the late 1800s and early 1900s. In fact, several
prominent strong men of the time actually published books on strength training.
However, none of this was research-based and misinformation or myths about the
dangers of strength training also existed. This dissuaded some individuals from lifting
weights and also discouraged scientists from researching this field.
One of the first actual research papers on strength training was published in 1894. In
what would be called a “Case Study” today, it involved two adult female subjects who
completed 2 weeks of grip strength training with their right hand only. The study
demonstrated the occurrence of what came to be called “cross-training” (ie. training only
the right hand also produced strength gains in the left hand).
Current and Ongoing Research
Since that first paper, thousands of strength training studies have been published over
dozens of research areas (Kraemer et al., 2017) with tens of thousands of participants
and a wide variety of training modes – including resistance bands.
The vast majority of these studies found (and new studies continue to find) that
an appropriately designed strength training program is safe and beneficial for healthy adults.
Since the 1970s the American College of Sports Medicine (ACSM) and the National
Strength and Conditioning Association (NSCA) have issued and regularly updated a
series of “Guidelines” and “Position Stands” on resistance training for all ages, further
establishing this mode of exercise as beneficial to health and wellness.
Additionally the ACSM recently published a highly relevant paper entitled “The Coming
of Age of Resistance Exercise as a Primary Form of Exercise for Health”.
Key Research Findings
Safety
As well as the Guidelines and Recommendations cited above, a series of studies and
surveys, including by the World Health Organization (WHO), have consistently reported
the safety of resistance training programs in healthy adults.
Performance Benefits
A comprehensive review on Resistance Training for Health and Performance reported
improvements in a range of factors involved in sports performance, not simply limited to
strength and muscle mass increases. Such factors included vertical jump, speed,
balance, coordination, and throwing velocity.
Health Benefits
Major reviews of the literature have consistently associated resistance training with
reduced risk of all-cause mortality, as well for as a range of major non-communicable
diseases including Cardiovascular Disease (CVD), cancer, diabetes and lung cancer.
Other reported benefits of resistance training include reduced blood pressure and
improved sleep, as well as lower levels of depression and anxiety.
Lifestyle Benefits
The well documented effects of resistance training on strength, muscle mass and
functional fitness, are also associated with beneficial effects on lifestyle daily activities
including balance, reduced fall risk, gait speed, stair climbing, rising from a chair,
carrying groceries, etc. Resistance training is becoming recognized as a form of exercise
that is a necessity for healthy living.
Take Home Message
Research has shown that resistance training is safe and beneficial for healthy adults. It
builds a foundation of strength and muscle mass; preserves and/or increases functional
independence; reduces risk of chronic diseases and improves mental health.
Benefits Of Strength In Older Adults (64-100 years old)
History
Scientific studies conducted between 1894 and 1979 were the first systematic attempts
to understand how strength training affects the human body. This research reported that
strength training was safe and beneficial for individuals across the age range including
older adults
One of the first studies specifically focused on older adults was published in 1961. The
authors reported increased strength in a group of 5 men and 15 women (62-84 yrs old)
after 6 weeks of lower limb training, three times per week. The authors also reported
that “No evidence of joint trauma was observed from the exercise in any of the
subjects”.
In the decades to follow, more resistance training studies with older adults began to
appear, albeit in small numbers. For example, Liemohn (1975), Moritani (1980),
Frontera (1988),
Pratley (1994), Phillips (1996), published studies with men and women
60-96 years old. All these reported safe increases in strength, function and/or muscle
mass.
Current and Ongoing Research
Since those early days, the research in this area has burgeoned, and now likely
thousands of strength training studies have been published with older adult participants.
Two major international professional bodies have recently published guidelines for
Resistance Training/Exercise with older adults.
The American College of Sports Medicine (ACSM): Exercise and Physical Activity for
Older Adults
Key Research Findings
Safety
Despite the now well recognized benefits of resistance training, a recent National Health
Statistics Reports found that less than 15% of US older adults 65+ years old participate
in aerobic and muscle-strengthening activities as part of their leisure time. Reasons for
this include, among other things, safety fears and health concerns (Burton et al., 2017).
In contrast to this, the NSCA has stated that
“A properly designed resistance training program with appropriate instructions for
exercise technique and proper spotting is safe for healthy, older adults.”
Health Benefits
As well as strength and muscle mass increases, resistance training in older adults has
been shown to provide a range of health-related benefits. These include increased bone
density, reduced risk of heart disease, arthritis, type 2 diabetes, and osteoporosis, and
improved psychological and cognitive measures.
Lifestyle Functional Benefits
Resistance training programs in older adults have been shown to reduce fall risk as well
as provide a range of lifestyle-related benefits including balance, physical functioning
and activities of daily living. All of this helps to preserve the independence and quality of
life for older adults.
Sarcopenia
“Sarcopenia” is a medical term that refers to the loss of muscle mass with age that can
reach as much as 6% per decade after the age of 40 (Janson, 2010). Such losses are
also accompanied by losses in strength. This inevitably results in decreased physical
function and quality of life as well as increased morbidity and mortality (Brotto, 2012).
Because of this, Sarcopenia is regarded as a major cause of late life disability.
However, research has shown that resistance training is the most effective method for
the treatment of Sarcopenia.
A recent review reported that
“… resistance exercise is the standard non-pharmacological treatment approach for sarcopenia \
with significant positive evidence.”
Another major review reported that
“… moderate-intensity resistance training using elastic bands may be the best
training prescription for elderly patients with sarcopenia.”
Take Home Message
An expansive and still growing body of research has found that resistance training is
safe, beneficial, and recommended for older adults. It reduces the incidence and risk of
Sarcopenia; increases strength, muscle mass, and bone density; reduces fall risk;
improves balance and physical function; preserves independence and enhances quality
of life.