Elizabeth Haggerty
BIO 430
4-16-18
High femoral bone mineral density and the ability to increase bone mineral density in the
femoral neck seems to be positively correlated with intense exercise (Mussolino et al). The
literature being examined during this investigation will focus on reputable peer reviewed studies
done under consistent conditions. While searching the articles to support my hypothesis, I will be
looking specifically for articles/studies which use similar data analysis techniques such as X-Ray
absorptiometry to measure body composition before and after exercise as well as final bone
mineral density in the femur. X-Ray absorptiometry scans of the femur also assist in determining
cross sectional geometry of the bone and provides an accurate reading of bone structure Hind et
al).
Of the studies and articles found thus far through my research, most have shown a direct
correlation between diseases which tend to cause bones to weaken such as cancer, osteoporosis,
and fibromyalgia and exercise to refortify bone mineral density. Cancer treatments, especially
chemotherapy, are known to increase bone fracture risk and increase bone density loss. Exercise
may offer a solution to the problem of weakened bones as well as offer a more cost-effective
treatment (Via et al). Although this investigation will not be focusing on the use of exercise to
treat debilitating illnesses, this information is extremely useful in supporting my hypothesis that
high impact exercise increases femoral neck bone mineral density.
This investigation will focus on determining which type of exercise increases femoral
bone mineral density most significantly. It is my hypothesis that high impact hopping or longdistance jogging exercises will increase femur bone mineral density more than long-distance
walking or other light physical activities. Due to the abrupt, high strain, and high magnitude of
hopping exercises, it is widely thought that this method of exercise is most beneficial to femoral
neck or hip BMD (Callreus et al).
1.
Mussolino ME, Looker AC, Orwoll ES. Jogging and bone mineral density in men: results from
NHANES III. American Journal of Public Health. 2001;91(7):1056–1059.
This article focused on the effects of jogging on bone mineral density in the femoral
neck. Men were chosen as the group of interest due to the previous lack of conclusive studies on
men’s femoral neck bone mineral density and the effects of exercise; past studies focused mainly
on women. Data for this study was retrieved from the Third National Health and Nutrition and
Nutrition Examination Survey (NHANES III). The NHANES III collects data from a voluntary
survey. Men between the ages of 20-50 years were selected and divided into one of three groups:
men who jogged more than 9 times per month, men who jogged 1-8 times per month, and men
who did not jog at all. The non-joggers were further divided into those who did not jog but
participated in other physical activities such as walking or gardening, and those who lived a
sedentary lifestyle. Bone mineral density was measured via dual energy x-ray absorptiometry.
Lifestyle information such as age, smoking status, alcohol consumption, food intake, and chronic
health conditions was gathered by interview. These factors were adjusted for during analysis.
Analysis was performed using the statistical analyzation software SUDAAN and SAS.
The authors concluded that the mean femoral bone mineral density of joggers was 5%
higher than Bone mineral density in non-joggers who participated in some type of physical
activity (walking, gardening etc). Bone mineral density of joggers was 7.7% higher in joggers vs
non-joggers who lived a sedentary lifestyle. The results also suggest that there is a limit to the
benefits of jogging on bone mineral density. This ceiling shows that there may be a point where
bone mineral density is no longer affected by jogging and benefits can no longer be seen. No
such ceiling seems to be reported in other studies which focus on the effects of hopping and
jumping exercises on bone mineral density. This suggests that the effects of hopping exercises
may outweigh the possible effects of jogging; in comparing this article to others on the subject, I
find that this idea is heavily supported.
This study focused solely on jogging frequency, but it may have benefitted from focusing
on distance and pace as well. It was suggested that there may be a ceiling to the positive effects
of jogging on bones, however, to determine this distance and pace should have been examined
along with frequency. Due to the information for the study coming from the NHANES III, which
did not include information on distance or pace, the results are limited. This study relied heavily
on self-reported data. Information about jogging frequency, health status, and chronic health
conditions were obtained by personal interview. This method has the potential for errors due to
bias or incomplete participant disclosure. Participants may have intentionally or unintentionally
excluded crucial information.
This article provides convincing data to support the idea that jogging significantly
increases BMD. Although it does not address the impact of hopping exercises it is still
supportive of my original hypothesis; regular jogging increases bone mineral density in the
femoral neck much more significantly than sporadic walking or light physical activities. I will
need to gather more data from other articles to confirm my hypothesis that hopping or long
distance jogging exercises are the best way to improve femoral bone mineral density.
2.
Eatemadololama A, Karimi MT, Rahnama N, Rasolzadegan MH. Resistance exercise training
restores bone mineral density in renal transplant recipients. Clinical Cases in Mineral and
Bone Metabolism. 2017;14(2):157.
This study focused on the effects of weight bearing activities on bone mineral
density in kidney transplant patients. Kidney transplant recipients tend to have reduced bone
mineral density (BMD) in the long bones (e.g. femur) and in the lumbar vertebrae of the spine;
the femoral neck and lumbar spine are the two areas on which the authors chose to focus their
attention. For the purpose of providing support for my hypothesis, I will focus on the aspects of
this study which focus on BMD in the femur. Bone mineral density loss may occur in kidney
transplant recipients due to lack of physical activity and the adverse effects of anti-rejection
drugs. Rapid bone mineral density loss has been reported in 28-88% of renal transplant patients.
Exercise is a cheap alternative treatment for the bone loss related symptoms of renal
failure/disease. Exercise also may reduce the need for potentially harmful medications which
may leave the patient feeling weak and weaken their bones as a result.
Participants of the clinical trial were recruited due to their history of kidney transplant
within one year of the study. The participants were also evaluated based on history of bone
fracture, cardiovascular disease, diabetes, and other bone diseases. The 24 participants were
divided into two groups; one group did weight training exercises for 12 weeks and the other
group was the control which received no weight training. This study used the same method to
evaluate BMD as study number one, X-Ray absorptiometry, to evaluate femoral BMD.
It was discovered that the group which received 12 weeks of guided weight training saw
a 1.4% increase in femur BMD. The control group which received no guided weight training saw
a decrease in femur BMD. This study confidently concluded that weight training is a great way
to reduce the negative effects of osteoporosis and improve BMD in kidney transplant patients
without the use of potentially harmful medications. It also concludes that the effects of using
muscular force are greater than the effects of gravity resistance activities.
This study used a very small sample size, only 24 participants, which may limit the
strength of our results. However, small sample size is to be expecting when conducting a study
as specific as this one. Locating renal transplant patients who are interested in participating in a
study requiring time and high levels of physical activities may be difficult. Another weakness of
this study is that, when comparing to other peer-reviewed studies on the subject, this particular
study contained a great amount of grammatical errors. In my opinion, this jeopardizes the
integrity of the study.
This article directly addresses my hypothesis by measuring the degree to which femoral
BMD increases with exercise. It even goes on to compare weight bearing exercises such as
lifting weights to gravity resistance training exercises such as jogging. The article leans more
toward weight lifting as being more likely to increase BMD than jogging, which somewhat
supports my initial hypothesis. However, it does not address the impact of hopping exercises
which do not involve the addition of weights and rely solely on one’s own body weight. Weight
lifting is a high impact, short duration, high shock activity just as hopping or jumping exercises
are; therefore, this study indirectly supports my hypothesis, but further research on the subject is
needed.
3.
Pellikaan P, Giarmatzis G, Sloten JV, Verschueren S, Jonkers I. Ranking of osteogenic potential
of physical exercises in postmenopausal women based on femoral neck strains. Plos One.
2018;13(4).
This study focused on femoral neck fractures in postmenopausal women specifically. The
authors wished to investigate which type of physical activity best induces osteogenesis and bone
mineral density increase; they believe that to see an improvement in femoral neck strength due to
exercise, the activity must be strenuous (brisk walking or slight jogging vs leisurely walking).
A small group of post-menopausal women were chosen to participate in this study.
Women with prior conditions such as lower limb fractures or lower limb pain were excluded
from the study. Participants were asked to walk and run on a treadmill and perform hopping
exercises. Ground force was measured through plates underneath the belt of the treadmill as well
as on the ground where the jumping exercises were performed. Motion of the bones and muscles
as well as impact felt by the bones were measured and evaluated.
The impacts of each activity (walking, jogging, and hopping) were measured based on
tensile strain on both the inferior and superior part of the femoral neck. The inferior femoral neck
experienced the most strain during the hopping exercises, specifically during the propulsion
stage of the hop. The superior part of the femoral neck experienced the most strain during the
brisk walking exercises, followed by running. Exercises which induce high levels of strain show
the highest increase in BMD in the femoral neck. However, age and fracture risk must be taken
into consideration. Elderly postmenopausal women should not participate in hopping exercise,
although they seem to be the most beneficial to femur strength, due to their high hip fracture risk.
The article itself states its potential limitations of its methods. In order to obtain a generic
musculoskeletal model and a template to estimate the material properties of femoral necks in the
elderly female population, a CT scan of a healthy 60-year-old male was used. This may be a
source of error as the healthy male sample does not properly represent the possible osteoporotic
population that is elderly postmenopausal women.
This article may help support my hypothesis by providing data on the impacts of running
vs walking on femur BMD strength increase. However, because different exercises impacted
different parts of the femoral neck differently, the results of this study to not directly support my
hypothesis. This study does further support the general idea that exercise increases femoral neck
BMD, and that specific types of exercise have varying levels of impact on the femoral neck.
4.
Senderovich H, Kosmopoulos A. An Insight into the Effect of Exercises on the Prevention of
Osteoporosis and Associated Fractures in High-risk Individuals. Rambam Maimonides
Medical Journal. 2018;9(1).
This study focuses on which type of exercise has the highest potential to prevent
osteoporosis in high risk populations. Like the previous study, this one also focuses on the safety
of proposed exercises due to high risk for bone fracture in the participants. Current treatments for
osteoporosis rely mainly on medications which may have adverse effects on the patients. A
common treatment, hormone replacement therapy may increase risk of heart attacks, strokes, and
certain cancers. The goal of this study is to investigate the possible treatment of osteoporosis
through exercise. The use of exercise as a treatment has the potential to reduce financial hardship
on families by decreasing or completely ridding of the need to take expensive osteoporosis
drugs.
The authors of this article chose four peer reviewed, scholarly articles which investigated
the effects of high impact and low impact exercise on femoral BMD. High impact exercise was
defined as activities that require both feet to leave the ground (running, jogging etc). Low impact
exercise was defined as activities that require one foot to be on the ground (hiking and walking).
Results indicated that high impact activities led to a significant femoral BMD increase
and increase overall skeletal integrity. High impact activities may help decrease the risk of
osteoporosis.
This article, much like the previous four, concludes that high impact exercises such as
running jogging significantly improves femoral neck strength and BMD. Not only does this
article strengthen the idea that jogging increases femoral BMD, but it states the benefits of
exercise on the prevention or slowing of the disease osteoporosis. This again does not directly
support my hypothesis but reinforces the idea that rigorous exercise increases femoral neck
BMD. I may want to consider broadening my hypothesis to state that high impact running
significantly increases femoral neck BMD.
5.
Via JD, Daly RM, Fraser SF. The effect of exercise on bone mineral density in adult cancer
survivors: a systematic review and meta-analysis. Osteoporosis International.
2017;29(2):287–303.
This article focuses on the treatment of bone mineral density loss in male cancer patients.
The positive impacts of weight bearing exercises or resistance training in healthy males are well
understood. This study focuses on the less understood impact of exercise on BMD in males
suffering from cancer. Although they improve survival outcomes, a common side effect of
cancer treatments such as chemotherapy or endocrine therapy is accelerated bone loss. Exercise
has been shown to improve physical function, sexual function, and fatigue in those with cancer.
However, the effects of exercise on the bones of cancer patients have not been studied in depth.
The authors of this article chose to compare several articles on the subject. All chosen
articles used the same method, X-Ray absorptiometry, to study bone mineral density in the
femoral neck. Unlike the previous four articles mentioned, the studies that the authors of this
article chose to evaluate did not show significant increase in femoral neck BMD. Instead, they
showed evidence of improved lumbar spine BMD whereas the previous four studies did not
show improved lumbar BMD. It is unclear whether the patient’s cancer diagnosis contributed to
the lack of improvement in femoral neck BMD. The article itself states that results may be
hindered due to the lack of studies available on the subject. Although this article was
inconclusive, the other articles found during the research process provide a strong basis for my
hypothesis.
Admittedly, this article being a review of other studies did have its disadvantages to me
as a researcher. Also, the fact that the results found by the authors of this article did not coincide
with those of other articles I have found during my research leads me to personally discredit this
particular article. I would probably not include this article in my research. I would look for
articles by authors who have performed a new study on femoral neck BMD and exercise on their
own.
6.
Takamine Y, Ichinoseki-Sekine N, Tsuzuki T, Yoshihara T, Naito H. Effects of voluntary
running exercise on bone histology in type 2 diabetic rats. Plos One. 2018;13(2).
This study focused on the correlation between type-2 diabetes and bone strength.
Laboratory rats were used to clarify the histological properties of bones in diabetic rats. The goal
of this study was to determine whether exercise assists in maintaining bone homeostasis in rats.
If the presence of positive correlation between exercise and bone health in rats is supported by
this study, we can likely apply the same idea to humans. Exercise may not only assist in bone
modeling and remodeling, it may assist in the improvement of insulin resistance. Bone fragility
is often a concern in human diabetes patients, especially if they are elderly. Bone fragility in
individuals with diabetes may be caused by adiposity, insulin resistance, fatty acid composition,
and hormones. The buildup of fat in bone marrow impacts bone turnover decreasing bone
volume. The finding that exercise helps to maintain homeostasis and bone remodeling would be
significant to future diabetes treatments for humans.
The types of rats chosen were Otsuka Long-Evans Tokushima Fatty (OLETF) rats, and
Long-Evans Tokushima Otsuka (LETO) rats. It had been previously found that OLETF rats
develop diabetes at 25 weeks of age. The rats were separated into four experimental groups:
OLETF sedentary, OLETF exercise, LETO sedentary, and LETO exercise. All animals were
provided with the same housing conditions and diet to ensure consistent results. The rats in the
two exercise groups were allowed access to a running wheel for 20 weeks of the study; activity
was measured by a counter. Distance ran was obtained by multiplying the number of wheel
revolutions by the circumference of the wheel.
All rats were euthanized at 25 weeks of age. Their blood was drawn and centrifuged to
separate the plasma from the serum, white adipose tissue was extracted, and the right femur was
harvested from each test subject. Blood glucose levels were measured, plasma insulin levels, and
serum adiponectin and leptin levels were analyzed using the blood sample earlier obtained. To
test the strength of the right femur a bending test was performed during which force was applied
to the metaphysis of the bone until the point of fracture. A microscopic analysis of the femur
growth plate was done to measure bone marrow fat.
The total distance on the running wheel between the two exercise groups did not differ
significantly. Body weight did not differ between the groups before the experiment began;
however, at the end of the 25-week experiment, the OLETF sedentary group was heavier than
the LETO sedentary group. This study concluded that voluntary exercise lessened the growth of
bone marrow fat; bone marrow fat inhibits normal bone remodeling. The results of this study
show that exercise has beneficial effects on the prevention of diabetes and bone remodeling.
This study focuses on many aspects which may not be relevant to my study. Results for
blood glucose and blood insulin levels do not directly support my hypothesis. However, The
results regarding bone mechanical strength and bone marrow fat do support my hypothesis that
running exercises increases femur strength.
The authors of this study point out a few possible errors in their experimental results. It
was found that maximum breaking force and two-dimensional bone volume was not impacting
positively by running. This could be due to the short wheel running period (5 months). Two other
studies on this subject allowed the rats the run on a wheel for 9 months and 17 months. Further
study is needed to find the relationship between bone marrow fat accumulation and bone loss.
Further study is also needed to clarify whether adipose tissue volume in bone is impacted by
exercise. The authors of this article compare their results thoroughly with the results of other
studies on the subject; this makes the article more credible in my opinion even though their
results do not match perfectly with those of other studies. The authors also discuss possible
defects in the study which I find makes it more credible and easy to duplicate; future studies can
use this studies method as a basis while keeping its defects in mind when designing a new set of
methods and controls. This study provides a wonderful framework for future studies.
7.
Zhang L, Chen X, Wu J, Yuan Y, Guo J, Biswas S, Li B, Zou J. The effects of different
intensities of exercise and active vitamin D on mouse bone mass and bone strength.
Journal of Bone and Mineral Metabolism. 2016;35(3):265–277.
This study uses mice to investigate how exercises of different intensities affect bone mass
and strength. It also investigates the effectiveness of Vitamin D on increasing bone mass in
comparison to exercise. The investigation of the effects of vitamin is not relevant to my
hypothesis, therefore will not be considered. Exercise has proved to be a reliable therapy for
increasing bone strength and reducing stress fractures. There seems to be a correlation between
frequency and intensity of exercise and bone mass/strength; however, information on the
relationship is scarce. Two-month-old mice were used in this study due to the responsiveness of
growing bones to exercise. Although growing bones are more responsive to exercise, older bones
are also responsive.
72 2-month-old mice were divided into eight groups with nine mice per group. All mice
except for the control group and vitamin D group were assigned to treadmill running exercises of
varying intensities for five weeks. The mice were euthanized after the experiment and both
femurs of each mouse were taken out. Soft tissue was removed from the bones. Dual-energy Xray absorptiometry was used to measure bone mineral density of the femur, this is the same
method used in studies one and two to measure femoral BMD. A three-point bending test was
performed for biomechanics analysis as in article six.
This study found that a medium level of exercise increased femoral BMD in mice more
significantly than low or high levels. A medium level of exercise was found to reduce osteoclast
activity therefore inhibiting bone resorption and increasing bone mass. Osteoblast activity was
increased in mice with a medium level of exercise as well; however, the increase in the number
of osteoblasts in the femur was not reflected in the increase of bone strength. The authors of this
study are not sure why this has happened, and further investigation is needed.
Other studies on this subject have concluded that any level of exercise is beneficial to
bone mass and density whereas this study found that only medium levels of exercise were
beneficial to mouse BMD. The difference in results may be due to the age of the mice used or
different exercise protocols.
Although the results of this study vary from other studies on this subject, it still somewhat
supports my hypothesis that high endurance jogging increases bone mineral density more than
low endurance walking or other low endurance physical activities. The finding that medium level
exercise most significantly increased bone mineral density for this study aligns with the idea that
when exercise activity is increased, bone mineral density also increases. It was discovered by a
previous study that there may be a ceiling to the benefits we can see from physical exercise, this
study seems to suggest a similar idea.
The authors of this study state that further studies are needed to fully understand how
osteoclasts and osteoblasts are impacted by varying levels of exercise. A medium level of
exercise may be most beneficial to femur BMD due to the balance of bone resorption by
osteoclasts and bone remodeling by osteoblasts. It is unclear whether the addition of vitamin D
caused the results to favor medium level exercise.
8.
Ireland A, Rittweger J, Degens H. The Influence of Muscular Action on Bone Strength Via
Exercise. Clinical Reviews in Bone and Mineral Metabolism. 2013;12(2):93–102.
This review investigates the results of multiple studies on the effects of exercise on lower
limbs amongst different age groups and amongst the sexes. Ground reaction forces produced by
exercise vary greatly based on the type of activity performed. Walking produces the smallest
GRFs and jumping/hopping exercises produce the strongest GRFs in the lower extremities; this
is due to the strain being exerted on the muscle and the force behind the muscle movement.
Therefore, exercises involving sudden and strong muscle contractions should strengthen bone
more than steady, even paced exercises such as jogging or walking.
During the investigation of the effects of exercise on the bones of children and
adolescents, it was determined that bone mass more than doubles in females and nearly triples in
males between the ages of 8 and 18. This period provides a window for exercise to assist in
strengthening of bones before the end of puberty, when benefits seen from exercise tend to
decrease. It was noted that jumping exercises alone were effective in improving bone strength in
the femoral neck in children and adolescents.
Peak bone mass occurs in the second or third decade of life. When compared to studies
on exercise and bone mineral density in children, there are very few studies done on the effects
of exercise of bone mineral density loss in young adults. Although peak bone mass increases
occur in the second or third decade, bone mass can still be increased in late adulthood. Bone
strength tends to decrease significantly with age due to bone becoming less responsive to
mechanical stimuli, tendon stiffness, and osteogenic response of bone cells. The ability to
perform strenuous exercise with advanced age decreases significantly in most cases. Therefore,
not only is it more difficult for older individuals to stimulate their muscles and bones enough to
initiate bone growth, there is also a lack of information on the relationship between exercise and
BMD in the elderly population. The information that has been collected points to the same
conclusion as other studies included in this annotated bibliography, exercise increases bone
mineral density.
Much like the study by Pellikaan et al (3), it was found that hopping and jumping
exercises have the highest impact on bone mineral density in the lower limbs. This review
strongly supports my initial hypothesis that high impact or high endurance activity such as
jumping or running have a greater impact on BMD than light impact or light endurance
activities.
The results of the studies reviewed by the authors of this article may have been impacted
by a high study drop out and high noncompliance rate amongst participants. Children have the
highest drop out rate at 67%. Adults tend to have a higher retention rate averaging 76%. Very
high intensity or unsupervised exercise training result in higher drop out rates due to lack of
personal or outside motivation.
9.
Senderovich H, Tang H, Belmont S. The Role of Exercises in Osteoporotic Fracture Prevention
and Current Care Gaps. Where Are We Now? Recent Updates. Rambam Maimonides
Medical Journal. 2017;8(3).
This study focuses on which form of exercise best prevents fractures in women subjects
with osteoporosis. Exercise is the primary alternative to pharmacological treatments for
osteoporosis due to its ability to increase bone mineral density and bone strength. Patients
experiencing osteoporosis usually are unable to perform certain exercises safely, this is also
taken into consideration during this study. In previous studies, it had been found that high
intensity jumping or hopping exercises best improved bone mineral density in the femur.
However, these exercises may not be safe for a person of advanced age or compromised bone
strength to perform; other exercise options must be considered for these people.
It was found that short, moderate force, repetitive exercises were best for increasing bone
mineral density in elderly osteoporosis patients. This exercise in most cases is closely monitored
to ensure proper form. Resistance and balance training were also included to ensure safety and
reduce the risk of falls and fractures while exercising. There is currently no cure for osteoporosis
and lack of symptoms makes it difficult to detect. The current pharmacological treatments assist
in slowing down the breakdown of bone tissue, but they may have harmful side effects. Exercise
as a treatment is far more affordable and accessible.
The authors of this review performed a thorough search of MEDLINE and Cochrane
databases to collect recent literature on the impacts of exercise on osteoporosis and the reduction
of osteoporotic fractures. Of the 40 relevant results, only 16 were deemed useful. Trials in which
participants were not at risk for developing osteoporosis were excluded.
When performed twice per week, high intensity exercise increased mobility, physicality,
bone mineral density, muscle strength, and balance. A 40% reduction in falls and fractures was
reported due to increased bone and muscle strength as well as increased balance.
This review is credible because it had very high standards when searching for articles and
studies to use. Each one was scrutinized to ensure relevance and references for each study/article
were checked to ensure validity. Although my hypothesis is not specific to older patients with
osteoporosis, it still validates my hypothesis that high intensity exercise increases bone mineral
density in the lower limbs.
10.
Callréus M, Mcguigan F, Ringsberg K, Åkesson K. Self-reported recreational exercise
combining regularity and impact is necessary to maximize bone mineral density in young
adult women. Osteoporosis International. 2012;23(10):2517–2526.
This study focuses on young women 25 years of age. The goal of this study was to
evaluate the effects of recreational activity on bone mineral density. It is currently thought that
peak bone mass in women is reached by the age of 16-19 at the hip. This study takes into account
the age of the women and the potential for bone growth due to genetics. It was thought and
suggested by other studies that the type of mechanical stimuli applied to bones is crucial to
building bone mineral density. Bones tend to respond to high magnitude exercise with few
repetitions. Bones seem to have the ability to grow accustomed to repetitive exercises and cease
to produce an osteogenic response. Many studies on the subject investigate the effects of specific
exercises on bone mineral density; this study focuses on bone mineral density of people who
perform several types of physical activities at moderate levels at varying times.
One thousand and sixty-one young Caucasian women were randomly selected to
participate in this study. All of the women were citizens of the same city in southern Sweden.
One hundred and two women were excluded from the study due to pregnancy. Three more were
excluded due to not meeting the age requirement. A questionnaire was given to all participants
which asked questions regarding physical activity and other factors such as work, health, family
history, medical status etc. The authors of this study tested the questionnaire and participants for
reliability by asking 20 participants to retake the same questionnaire three months later; no
significant differences were found. Subjects graded themselves on a scale of one to six. A score
of one represents a sedentary lifestyle and a score of six represents regular physical activity.
Frequency of exercise was considered, but duration of activity was not.
Much like the study by Ireland et. Al, ground reaction forces were measured and peak
strain scores were assigned for each recorded activity. To determine the effects of physical
activity on bone mineral density, a linear regression analysis was performed. Lifestyle choices
such as diet and smoking as well as height and weight were adjusted for in the model. It was
found that high levels of recreational activity contributed to significantly higher bone mineral
density in the hip and lumbar spine. The women who participated in sports with high peak strain
had significantly higher bone mineral density at the hip and spine compared to women who
participated in low peak strain activities. The results of this study show that even women who are
not amateur athletes or elite athletes may increase bone mineral density with regular recreation.
The reliability of the questionnaire and care taken by the authors of this study makes this
study credible and therefore a good source to support my hypothesis. However, I am skeptical of
self-reported data use in studies as they may be biased. I also believe that information on
duration of activity should have been considered. This study is more relevant to everyday people
who do not participate in organized sports or activities. As long as we participate in some kind of
relatively high impact activity such as playing sports with friends or going for a run, we can
increase bone mineral density and decrease risk of fracture later in life just by doing something
we enjoy.
11.
Lucas JA, Lucas PR, Vogel S, Gamble GD, Evans MC, Reid IR. Effect of sub-elite competitive
running on bone density, body composition and sexual maturity of adolescent females.
Osteoporosis International. 2003;14(10):848–856.
Like a few of the previous studies, this study addresses the importance of attaining peak
bone mass during adolescence in order to prevent osteoporosis. Exercise may contribute to bone
development and growth, but competitive exercise may have adverse effects on bone mineral
density and bone development. The goal of this study is to assess the effects of moderate
exercise on bone density in adolescent females. Moderate exercise is studied because excessive
exercise during the critical period of puberty may delay the onset of puberty or interfere with a
normal menstrual cycle for young women. This potentially impedes the woman’s ability to reach
peak bone density. For this reason, young women are sometimes discouraged from participating
in rigorous competitive activities. This study eliminated those who participated in such activities
and focused instead on individuals participating in regular non-elite competitive athletics.
Forty-two participants between the ages of 12-14 were recruited from local schools and
athletic clubs. All interested participants were interviewed by phone for additional screening.
Only Caucasian volunteers were chosen based on the difference in bone density amongst
different races. Potential participants were also eliminated if there was a potential for pregnancy
or if they had a physical disability. The participants were separated into groups: runners,
described as those who were involved in weekly training sessions with a coach, and non-runners.
Bone mineral density of the femur was assessed using a method used in many studies on this
subject, X-ray absorptiometry. Participants were asked to keep a diet and exercise diary.
Although there was a slight difference, it was found that there was no significant
difference in bone mineral density at the femoral neck between the non-runners and the runners.
The authors do acknowledge that this is strange based on the overwhelming evidence backed by
other studies that higher physical activity tends to create higher bone mineral density. It was
determined that the level of physical activity exhibited by the girls in the study, whether runners
or nonrunners, was not enough to have a detrimental effect on bone mineral density. Therefore,
according to these results, the level of activity would have to be much more significant than
training sessions one hour in duration 2-3 times per week in order to become detrimental to bone
mineral density in girls on this age.
The self-reported diet and exercise may create error in the results due to failure to report,
inaccurate serving sizes or nutritional data, and personal bias. Also, this study could have
benefitted from having a study group which ran or trained more often than 2-3 times per week
for one hour at a time. This would have strengthened the results of the study. I believe this study
should have focused on participants of a wider age range to show the bone mineral density
differences before and after puberty. It has been shown by other studies during my research that
physical exercise during the critical period of puberty forms a good foundation for healthy bone
mineral density later in life and assists in the prevention of osteoporosis. While the authors of
this study do address this critical period, they do not seem to adjust for it in their experimental
models.
12.
Hind K, Gannon L, Whatley E, Cooke C, Truscott J. Bone cross-sectional geometry in male
runners, gymnasts, swimmers and non-athletic controls: a hip-structural analysis study.
European Journal of Applied Physiology. 2011;112(2):535–541.
This study emphasizes the importance of mechanical loading of the skeleton in order to
strengthen and reinforce bone structure. Weight bearing exercise is the focus of this study as it is
believed that weight bearing exercise is the most beneficial as long as it is of the appropriate
magnitude and frequency. This study again focuses on the hip area, specifically the femoral
neck, as it is the most common site for osteoporotic fractures. The objective of this study is to
investigate differences in BMD between male athletes and male non-athletes, and between male
athletes from a variety of sports.
Male Caucasian runners, gymnasts, swimmers, and non-athletes between the ages of 1835 years were recruited for this study. All of the athletes involved trained for at least five hours
per day for the past three years. Scans of the proximal femur were taken using X-ray
absorptiometry for each participant. Age height and weight were all adjusted for before
conclusions were drawn. It was found that gymnasts and runners had higher bone mineral
density than non-athletic controls. This is most likely due to the high impact nature of those two
sports. Runners and gymnasts showed greater resistance to strenuous loads on the lower limbs. It
was also found that individuals of short stature exhibited lower areal bone mineral density than
the taller participants. This is the first study I have found which states this connection between
height and bone mineral density. This could mean that the relationship is due to experimental
error, it there could be other factors unaccounted for which causes the relationship.
There seems to be a natural bias when running experiments of this nature. Differences in
bone mineral density between individuals who play different sports could be due to genetics and
self-selection into these specific sports. For example, those with a genetic predisposition for
strong bones and short stature may be more likely to excel in gymnastics. This study once again
supports the idea that hopping/jumping activities (gymnastics in this case) and running result in a
higher bone mineral density than low impact/effort physical activities. This is strongly illustrated
by the authors finding that gymnasts had significantly greater bone mineral density at the
proximal femoral neck in comparison to runners and control groups. Gymnasts activities tend to
involve a high occurrence of jumping, hopping, and short bursts of intense physical activity.
Therefore, the findings of this study directly support my hypothesis.
13.
Gast U, Belavý DL, Armbrecht G, Kusy K, Lexy H, Rawer R, Rittweger J, Winwood K,
Zieliński J, Felsenberg D. Bone density and neuromuscular function in older competitive
athletes depend on running distance. Osteoporosis International. 2012;24(7):2033–2042.
This study focused on the relationship between physical activity and bone performance, lean
mass, and neuromuscular performance in older individuals. Testing was performed locally and
only Caucasians participants were chosen based on the differences in bone density of other races.
Subjects were questioned based on their training every week and lifestyle. All who met the age
requirement could participate. Short, middle, and long-distance athletes were examined and their
bone mineral density was measured using X-ray absorptiometry before exercising.
Predetermined exercises were performed, they included a countermovement jump, one leg
hopping, and grip force tests. The countermovement jump exercise involved jumping as high as
possible from a squatting position. If my hypothesis is accurate, this exercise should have the
greatest impact on bone mineral density in the femur. Peak force was calculated and expressed
relative to the participants body mass. For the one leg hopping test, participants were asked to
perform ten continuous one leg hops.
Gender and age group were controlled for in the result experimental models. Factors
deemed inconsequential were emitted from the study before models were adjusted. The
relationship between age and impact of exercise was also accounted for before and after
controlling for height, body mass, and duration of exercise. The care taken by the authors of this
study to account for any possible variations in results makes this study more credible in my
opinion.
This study seems to agree with the results of several previously investigated studies
which found that running distance ceases to have an impact of bone mineral density after a
certain point. The results show that participants who ran short distances saw significantly higher
bone density than long distance runners; this may be explained some type of ceiling to bone
changes after a certain running distance.
This study does not account for physical activity during childhood or adolescence which
other studies I have investigated show is a crucial time period for the strengthening of bone in
later life. Those who established a solid foundation for healthy bone growth by being active
during the critical periods may have seen better results in this study; this should be accounted for
if this study is to be duplicated.
14.
Kemmler W, Bebenek M, Stengel SV, Bauer J. Peak-bone-mass development in young adults:
effects of study program related levels of occupational and leisure time physical activity
and exercise. A prospective 5-year study. Osteoporosis International. 2014;26(2):653–
662.
This study compares bone mineral density increase in two groups of university students.
Students enrolled in a dentistry program were hypothesized to have lower bone mineral density
due to a stressful and demanding course load and a low level of physical activity in their daily
lives. Students enrolled in a sports science program were hypothesized to have an increase of
bone mineral density due to high volume of intense exercise.
This study was an observational study spanning five years in southern Germany. The
students were selected for the study randomly by computer and contacted by mail. Eight
interested subjects were rejected due to diseases/medication which may compromise bone
metabolism, pregnancy, and change in study program; one hundred and fourteen students were
ultimately chosen to participate.
The regular study periods of students in both groups were closely examined to determine
the average amount of physical activity. The dentistry students took an average of 11 semesters
to complete their coursework. During this time students were required to attend workshops,
lectures, tutorials, clinical placements, and take regular exams. Based on students’ questionnaires
given at the end of the fourth month, the average weekly workload of the dentistry students was
approximately 34 hours per week. Work was more often than not performed in a sitting
positioned, standing work was less frequent.
The regular study period of the sports science students averaged nine semesters. During
this time students participated in 1050 obligatory hours of sport application. Testing, sports
practice, and leisure sports accounted for an additional 11.9 hours per week of sport application
on top of the 1050 hours required by the study.
Bone mineral density was measured using X-ray absorptiometry less than six weeks after
the beginning of the study and during a follow up assessment approximately 4.8 years after the
end of the study. Each measurement was taken at the same time of day to ensure consistency.
Only 76 of the original 114 study participants finished the study due to change in study
program, loss of interest, or change in study location. As expected, sports science students
sustained physical activity throughout the semester and physical activity of dental students
decreased. It was found that the bone mineral density for male sport science and male dental
students students increased more than their female counterparts. This discrepancy between
genders was not originally adjusted for, but after this difference was discovered the model was
adjusted to account for gender. After approximately 4.8 years, bone mineral density at all tested
skeletal sites (lumbar spine and femoral neck) increased significantly in sports science students.
Changes in bone mineral density for dental students varied more significantly. Femoral neck
bone mineral density decreased, however, lumbar spine bone mineral density increased. The
results from the sports science study group align with my hypothesis. The results from the dental
group show that a more sedentary lifestyle may be detrimental to femur bone mineral density,
but a light amount of activity such as walking to class may be beneficial to lumbar spine bone
mineral density.
The authors of this study took many precautions to ensure strong results. As previously
mentioned, the bone mineral density measurements were taken at the same time of day although
they were taken months apart. They also adjusted for varying study duration between the two
groups by assessing sports science students after their last semester in university or their first
months of school internship. Dental students were assessed during the semester break between
semesters nine and ten. The careful evaluation and adjustment for group differences adds to the
credibility of this study.
15.
Upala S, Yong WC, Sanguankeo A. Bone mineral density is decreased in fibromyalgia
syndrome: a systematic review and meta-analysis. Rheumatology International.
2016;37(4):617–622.
This review is fairly similar to the study on BMD in cancer patients (#5). A major
concern regarding individuals with fibromyalgia or other debilitating diseases is the possibility of
osteoporosis due to inability to exercise due to physical pain or lack of energy. Fibromyalgia
may also cause sleep disturbances, depression, and cognitive/memory problems, all of which
effect general health and wellness which may get in the way of physical fitness. This review was
conducted to better understand the association between fibromyalgia and its negative impacts on
bone mineral density.
Two of the authors of this study searched for studies in the MEDLINE and EMBASE.
References for all of the studies included in this review were evaluated for credibility. Studies
were chosen if they recruited participants from the general population or if they used data from
medical records of reputable healthcare facilities. The authors chose articles which compared
BMD measurements of individuals with fibromyalgia and healthy individuals. Of the 240 articles
found by the authors initial search, only four were chosen for review. All of the articles were
observational studies. In all four of the studies, it was found that patients with fibromyalgia had
significantly lower BMD than healthy individuals.
The authors scrutiny when choosing articles to review adds to the credibility of this
review. While this article does not prove or disprove my hypothesis directly as it does not
discuss types of exercise, it does speak of the detrimental effects of no physical activity. This
notion that lack of exercise decreases femoral neck BMD indirectly supports my hypothesis; It is
implied that exercise increases femoral neck bone mineral density. While it is not specific about
which type of exercise most significantly increases bone density, it acts as a good basis for more
research.
16.
Martelli S, Mokhtarzadeh H, Pivonka P, Ebeling PR. The Femoral Neck Mechanoresponse to
Hip Extensors Exercise: A Case Study. Journal of Osteoporosis. 2017;2017:1–9.
The goal of this study was to measure the femoral neck response to hip extensor
exercises. In the past, it had been difficult to determined which muscle groups being triggered
caused the femoral neck to respond to mechanical stimulus. The authors of this study examined
the femoral necks response when the hip extensor muscles contracted intensely.
This is the first study that I have come across which uses only one participant. A healthy
premenopausal Caucasian woman of average height and weight was chosen. The criteria for
choosing this participants were the following: the ability to perform intense impact activity, no
reported medical issues that may impact bone health, no back or lower limb pain, adequate
calcium intake, regular menstrual cycle, no previous pregnancies, and a relatively sedentary
lifestyle for 12 months leading up to the study. She underwent training for six months which
focused on the hip extensor muscle. She was given very specific exercises to perform for a
predetermined amount of time and repetitions.
Dual X-ray absorptiometry was used to detect changes in the femoral neck and
trochanteric regions. It was discovered that there were significant changes in the proximal
femoral neck causing the BMD to increase. The results were consistent with the authors idea that
exercising the hip extensor muscle results in an increase of BMD in the femoral neck.
There are several author noted limitations to this study. The results may be limited due to
there being a single subject. This study was performed on a healthy premenopausal woman;
however, it is older postmenopausal women who tend to suffer the effects of loss of BMD in the
femur due to osteoporosis. Older women would most likely see a slower bone response to
exercise. It is difficult to determine if the hip extensor muscle was the only one doing work while
the participant was exercising. Surrounding muscles may have altered the mechanical stimulus
generated by the hip extensor muscle.
This study supports my hypothesis and gives new insight to the cause of bone mineral
density that I have not seen before in other studies. It had been implied that working out certain
muscles impacts specific bones, but I had not seen a study which focused solely on this idea.
Overall, this study was helpful and provided great evidence to support my hypothesis but did
have its disadvantages which I have stated previously.
17.
Mędraś M, Słowińska-Lisowska M, Jóźków P. Impact of recreational physical activity on bone
mineral density in middle-aged men. The Aging Male. 2005;8(3-4):162–165.
This studies objective was to assess bone mineral density in middle aged men who
exercised recreationally. It is thought that the effects of exercise on bone mineral density lessen
with age with individuals between puberty and the age of 25 seeing the most significant results.
The subject group consisted of 38 men from the same socioeconomic background with similar
nutritional habits and leisure activities. All of the men examined were ex smokers, did not suffer
from any diseases and had similar BMIs.
Among the subjects, 22 were placed into the inactive group. Sixteen men were placed
into the active group. Assessment of bone mineral density was done by peripheral quantitative
computer tomography densitometry at the end of the radius. This method measures bone density
with a high degree of precision. The results of this study were inconclusive. No statistically
significant differences were found between the two groups in cortical, trabecular, or whole bone
mineral density. This could be because the study focused on recreation activity. This suggests
that more rigorous exercise is necessary to see results.
Because this study focused on the bones of the arm and the results were inconclusive, it
does not directly support my hypothesis. The particular exercises I am investigating
(jumping/hopping, running, walking) are not relevant therefore I can only use this article for
background information. This study gives a lot of good information about how exactly exercise
influences BMD and what exactly is going on in the muscle therefore I will still use it as a
source.
18.
This study focuses on the impact of jumping performance on bone mineral density in
young female gymnasts. The participants in this study were all prepubertal rhythmic gymnasts
and were studied for a three-year period. Femoral neck bone mineral density was assessed in 25
trained gymnasts and 25 untrained controls. The balance in numbers with the control and noncontrol group is an advantage to this study.
All of the girls in the trained group received very similar training to preserve consistency
for the three-year study period. Control subjects were only permitted to participate in their school
related gym classes, no other strenuous physical exercise was permitted. Height, body mass,
pubertal stage, and bone mass were all adjusted for. A questionnaire was used to gather
information about pubertal development. X-ray absorptiometry was used to gather information
on femoral neck bone mineral density.
After the three-year study concluded it was found that femoral neck bone mineral density
increased in the rhythmic gymnasts. This finding is consistent with the majority of studies that I
have seen on the subject. The results also imply that jumping or hopping exercises increase
femoral neck density more significantly than other exercises; this supports my initial hypothesis.
19.
Uusi-Rasi K, Haapasalo H, Kannus P, Pasanen M, Sievänen H, Oja P, Vuori I. Determinants of
bone mineralization in 8 to 20 year old Finnish females. European Journal of Clinical
Nutrition. 1997;51(1):54–59
The goal of this study was to determine which exercises or activities cause the most
significant bone mass and bone density increases in young women, particularly focusing on
young women from Finland. A cross sectional study was preformed on 176 young females ages
8-20. They were recruited through an open invitation posted at local schools. The authors of this
study chose to focus on young women 8-20 due to the belief that sexual maturation has an
impact on bone mineral density. All participants were non-smokers, healthy, with no history of
disease, prior injury, drug use or anything else which may have compromised their bone mineral
density.
Height, weight, calcium intake, and age were all taken into consideration when finding
participants for this study. It was found that calcium intake has a limited impact on bone mineral
density when intake exceeded a certain amount; there seems to be a ceiling on the benefits seem
from calcium intake alone. This study cited another study by Welten et al which found that
physical activity was more important than calcium intake when it came to increasing bone
mineral density. The calcium intake of the subjects in the aforementioned study was equal to the
intake of the subjects of this study. Body fat percentage was measured using calipers and
measurements were taken from several sites. In each subject, bone mineral density was measured
at the lumbar spine, femoral neck of the right leg, and dominant distal radius, but for the purpose
of this research I will focus on the measurements taken from the right femur. Like most studies I
have seen on the subject, X-ray absorptiometry was used to measure bone mineral density. All
measurements and analyses were done by the same lab technician; this ensures consistency in the
results. The X-ray absorptiometry was calibrated daily to ensure proper readings. Some of the
younger participants were excluded from this study due to low initial done mineral density; bone
mineral density could not be properly determined using X-ray absorptiometry in these subjects
and their data was excluded.
The results show that there is a high correlation between body weight and bone mineral
density; this is consistent with other studies on the subject. This is emphasized by the fact that
younger participants were excluded from the study due to lack of X-ray absorptiometry results.
Younger, more lightweight participants had very low bone mineral density and it was
undetectable or inconclusive. There was an increase in femoral bone mineral density naturally
with the progression of age over the three-year period. Physical activity was the only nongrowth-related factor associated with bone mineral density increase. The group which preformed
regular strenuous exercise saw a significant increase in femoral neck bone mineral density.
Physical activity was found the be beneficial to bone mineral density in both pre and postpubertal girls.
This study supports the idea that increasing bone mineral density between the critical
periods of puberty and menopause is important in creating a strong basis for the prevention of
osteoporosis and weak bones later in life. Many studies I have investigated also support this idea.
This study does not investigate the importance of duration of activity, frequency, or intensity on
bone mineral density; further investigation is needed to determine the importance of these
factors. The broadness of this study makes it weaker than other studies on the subject. However,
the importance of the results of this study should not be ignored.
20.
Lanham-New SA, Thompson RL, More J, Brooke-Wavell K, Hunking P, Medici E. Importance
of vitamin D, calcium and exercise to bone health with specific reference to children and
adolescents. Nutrition Bulletin. 2007;32(4):364–377 .
This study once again emphasizes the importance of optimizing bone health during early
age. As we have seen, a great way to do this is through physical exercise. Increases bone mineral
density during childhood may prevent the onset of osteoporosis and maintain skeletal integrity.
The key to achieving skeletal integrity is to increase bone mineral density through exercise
during a crucial period of early adulthood/late adolescence. Bone is a living tissue that has the
ability to change and adapt when it is put under mechanical stress. It is thought that one in two
women and one in 12 men older than 50 years of age will suffer from osteoporosis. This article
focuses on other factors such as vitamin D consumption that may assist in the strengthening of
bone, however, for my research I will be focusing solely on the impacts of physical exercise on
bone density.
This article focuses mainly on diet therefore there is a considerable amount of
information in this article that will not be used in my research. However, it still provides some
useful information to strengthen and support my hypothesis.
These 20 articles have shown that exercise, particularly running and hopping/jumping,
significantly increases femoral neck bone mineral density. These articles have shown that
patients suffering from a wide range of ailments which potentially cause bone mineral density to
decrease may see improvement in their strength and health due to exercise. The review done by
Upala, Yong, and Sanguankeo focuses on the link between the disease fibromyalgia and low
bone mineral density. It was found that the detrimental effects of fibromyalgia on bones can be
treated with physical exercise. The current treatments for cancer tend to not only weaken patients
but compromise bone mineral density. Exercise may assist in alleviating these symptoms (Via et
al). Physical exercise has also been found to significantly reduce the risk of osteoporosis in
menopausal and postmenopausal women as illustrated in the studies done by Martelli et al,
Belayy et al, Lucas et al, Callreus et al, and Sendervich et al. Studies done strictly on the effects
on the femurs of men such as the one done by Gannon et al shows that there are differences in
the impacts of exercise between the genders and these differences must be controlled for. It was
also made clear by my research that it is very important to begin building healthy bone mineral
density early in life to prevent osteoporosis and fractures later in life (Laham-New et al, Bebenek
et al) .The idea that running and hopping significantly increases femur BMD and walking
increases femur BMD more than a sedentary lifestyle has been strongly supported by the
evidence shown in these studies therefore I am confident in the strength of my hypothesis.