# Background Information

Bone health can be thought of as a banking system: the more you deposit earlier in life, the greater the safety net against debilitating diseases such as osteoporosis you possess later on in life. Evidence has shown that up to 90% of peak bone mass is acquired during adolescence, with females on average achieving this by the age of 18. In other words, the more load-bearing training you are exposed to earlier on in life, the greater the bone mineral density stores contained, in addition to decreased risk in developing conditions such as osteoporosis. This relates to Wolff’s law, which states that bone will adapt to the load that it is placed under.
According to the Australian Bureau of Statistics, 8% of females between 15 – 17 years old are meeting resistance-based training guidelines. This is poses as a worrisome dilemma due to the critical period in which adolescence is for physical growth and development in both males and females. These numbers in exercise participation have also proven to strongly indicate future participation in habitual exercise in adulthood as shown in figure 1 below, thus further elevating the importance of implementing future interventions that are recommended in various studies related to bone health in adolescents.
Why the spotlight on females?
Whilst the inadequate levels of physical activity are the main risk factor for poor bone health across both sexes, it is not the only contributing factor. Due to the vast hormonal differences between males and females in conjunction with subsequent age-related declines, females are more inclined to decreases in bone health than males due to the role that oestrogen has on osteoclast and osteoblast (bone cell) activity during the ever-constant bone remodeling and resorption phases.

# About the Researchers

As mentioned earlier, one of the best interventions for deposition into the bone health bank is resistance training. There are many studies backing this claim, just as researchers David L Nichols (PhD), Charlotte Sanborn (PhD) and Anna Love (MD) have shrewdly eluded to. As this is a popular research subject, there is a high likelihood for disunity between investigators, however the qualifications of the researchers in question cannot be undermined. Each researcher has been involved in many different studies in similar fields (85, 8 and 5 respectively) out of astute institutions: Texas Women’s University and Lerner Research Institute.

# About the Study

In regard to the study itself, discrepancies between resistance training and control groups were measured using dual-energy x-ray absorptiometry, a gold standard measure for many different physiological facets which includes bone mineral density. The measures used allowed for the production of significant, high level results, akin to similar research: resistance training has a positive effect on bone mineral density. This is demonstrated in significant increases in femoral neck (thigh) bone mineral density compared to the control group. Surprisingly, there were no significant differences in total bone mineral density between the control group and the training group, thus contradicting similar studies which found increases in full body bone mineral density. These results allowed the researchers to conclude that resistance training is a potential method for increasing bone density in female adolescents, whilst sighting implementation in an education capacity most appropriate for practicality purposes and ensuring participation.

# Real Life Ramifications

Despite minor contradictions in the aforementioned results of the study in comparison to other studies, it can be said with great confidence that resistance training is associated with great levels of bone mineral density, especially in bones with a larger surface area. This is supported by physiological processes in which muscular contractions require calcium for function, thus stimulating osteoblast and osteoclast (bone cell) activity. The degree to which bone cellular activity is stimulated depends on the amount of resistance training/load-bearing exercise that is undertaken, again relating to Wolff’s Law.
Confidence in the results about real-life repercussions stems from the researchers themselves. Their qualifications are second to none, however this does not always equate to meaningful, scientific conclusions. This refers to the phenomenon of Egocentric Bias, in which factors such as bias and ‘ego’ can influence the methodology, and subsequently the conclusions, of the study.
When presenting the results, the three authors are quite vigilant in terms of interventions moving forward. They provide the results with caution, rather than certainty, as evident in the wording of their conclusion: “…a potential method for increasing bone density in adolescents, although such a program would be best done as part of the school curriculum”. This type of wording may be to reflect the few conflicting results, thus opening an opportunity for further research into the subject. Nonetheless, the results presented are consistent with those found in similar studies, therefore confidence in recommended interventions should reflect as such.
So What Does All of this Mean for Female Adolescents in the General Population Moving Forward?
The bone health of Australians has always been a major concern, due to the lack of exercise being conducted throughout society as a whole, especially in the critical developmental period that is adolescence. The results from the study, as shown in figure 2, provide decisive evidence proving that resistance exercise is a major catalyst for bone growth and development. This will hopefully spur future increases in participation of habitual exercise as laid out by Government health programs such as the National Physical Activity Guidelines.

# National Physical Activity Guidelines

Studies comparable to this study on bone health in female adolescents, in conjunction with Government-led research, have led to the development of the National Physical Activity Guidelines.
These guidelines have also helped shape curriculum interventions. With sections dedicated to young people, encompassing ages 5 – 17, these National Physical Activity Guidelines recommend participation in moderate to vigorous physical activity for 60 minutes a day. Some examples of activities that will provide such a stimuli are predominantly team based sports, including:
* Football
* Basketball
* Netball
* Swimming
* Dancing
* Bike Riding
In regard to activities focusing on muscle strengthening, it is recommended three 60 minute sessions be undertaken per week. Such activities will provide adequate stimuli for participants to meet these requirements. Some examples include:
* Pushups
* Sit-Ups
* Lifting Weights
* Yoga
* Climbing
* Running
Participating in such activities will provide an adequate stimuli, therefore inducing stimulation of bone cell activity is required to reach adequate bone mineral density levels.

# Conclusion

Despite being a decade old, the aforementioned data provided by the Australian Bureau of Statistics remains relevant in today’s society, as shown by the many studies conducted since. These alarmingly low numbers of physical inactivity, especially in the critical development period of adolescence, has future ramifications spanning multiple facets of life pertaining to physical and mental health, as well as economic and lifestyle burdens. Studies such as this need to continue on expanding societal knowledge and keep delivering unequivocal conclusions to facilitate real change in a world surrounded by ambiguity.

# References

1. National Institute of Health for Osteoporosis and Related Bone Diseases. Osteoporosis: Peak Bone Mass in Women [Internet]. National Institute of Health. October 2018 [cited 18 August 2021]. Available From: https://www.bones.nih.gov/health-info/bone/osteoporosis/bone-mass
2. Hye Young Jin. Low Bone Mineral Density in Children and Adolescents with Cancer [Internet]. US National Library of Medicine. 30 September 2020 [cited 18 August 2021]. Available From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7538298/
3. H M Frost. Wolff's Law and Bone's Structural Adaptations to Mechanical Usage: An Overview for Clinicians [Internet]. 1994 [cited 18 August 2021]. Available From: https://pubmed.ncbi.nlm.nih.gov/8060014/
4. Web Report. Insufficient Physical Activity [Internet]. Australian Institute of Health and Welfare. 20 October 2020 [cited 18 August 2021]. Available From: https://www.aihw.gov.au/reports/risk-factors/insufficient-physical-activity/contents/physical-inactivity
5. Lumen Learning. Physical Development During Exercise – Module 3: Physical Development [Internet]. Lumen Learning. 2019 [cited 18 August 2021]. Available From: https://courses.lumenlearning.com/atd-fscj-childpsychology/chapter/physical-development-during-adolescence/#:~:text=During%20puberty%2C%20both%20sexes%20experience,(i.e.%2C%20growth%20spurt).&text=Because%20rates%20of%20physical%20development,than%20their%20later%20maturing%20peers.
6. Web Report. The Health of Australia’s Females [Internet]. Australian Institute of Health and Welfare. 10 December 2019 [cited 18 August 2021]. Available From: https://www.aihw.gov.au/reports/men-women/female-health/contents/lifestyle-risk-factors/physical-activity
7. David L Nichols. David L Nichols Research Profile [Internet]. Research Gate. 2008 [cited 22 August 2021]. Available From: https://www.researchgate.net/scientific-contributions/David-L-Nichols-38468108
8. Charlotte F Sanborn. Charlotte F Sanborn Research Profile [Internet]. Research Gate. 2008 [cited 22 August 2021]. Available From: https://www.researchgate.net/scientific-contributions/Charlotte-F-Sanborn-2089752534
9. Sundeep Khosla. Estrogen and the Skeleton [Internet]. US National Library of Medicine. November 2012 [cited 18 August 2021]. Available From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3424385/#:~:text=Direct%20estrogen%20effects%20on%20osteocytes,T%2Dcell%20regulation%20of%20osteoclasts.
10. Anna Love. Anna Love Research Profile [Internet]. Research Gate. 2008 [cited 22 August 2021]. Available From: https://www.researchgate.net/scientific-contributions/Anna-Love-2076870802
11. David Nichols, PhD. Resistance Training and Bone Mineral Density in Adolescent Females [Internet]. The Journal of Pediatrics. October 2001 [cited 18 August 2021]. Available From: https://reader.elsevier.com/reader/sd/pii/S002234760157482X?token=3B2C55C757110053CCFA0A3CE8207133014206BBEF05484BA7767414F0CC389BDF0BCE1F6A72A982E36F8990A8D465BD&originRegion=us-east-1&originCreation=20210816062549
12. L. Burke. Dual X-Ray Absorptiometry (DXA) for Measurement of Body Composition in Athletes: Experiences That Underpin the Importance of Optimising the Reliability of Measurement [Internet]. Journal of Science and Medicine in Sport. September 2017 [cited 22 August 2021]. Available From: https://www.jsams.org/article/S1440-2440(17)31392-0/fulltext.
13. Nichols DL, Sanborn CF, BonnickSL, Ben-Ezra V, Gench B, DiMarcoNM. The effects of gymnastics train-ing on bone mineral density. Med SciSports Exerc 1994;26:1220-5.
14. Morris FL, Naughton GA, Gibbs JL,Carlson JS, Wark JD. Prospectiveten-month exercise intervention inpremenarcheal girls: positive effectson bone and lean mass. J Bone MinerRes 1997;12:1453-62
15. A Ram Hong. Effects of Resistance Training on Bone Health [Internet]. US National Library of Medicine: National Institutes of Health. December 2018 [cited 22 August 2021]. Available From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279907/
16. Social Psychology. The Egocentric Bias: Why It’s Hard to See Things from a Different Perspective [Internet]. Effectiviology. 2021 [cited 24 August 2021]. Available From: https://effectiviology.com/egocentric-bias/
17. Department of Health. Physical Activity and Exercise Guidelines for All Australians [Internet]. Australian Government. 7 May 2021 [cited 22 August 2021]. Available From: https://www.health.gov.au/health-topics/physical-activity-and-exercise/physical-activity-and-exercise-guidelines-for-all-australians
* ↑ 1. National Institute of Health for Osteoporosis and Related Bone Diseases. Osteoporosis: Peak Bone Mass in Women [Internet]. National Institute of Health. October 2018 [cited 18 August 2021]. Available From: https://www.bones.nih.gov/health-info/bone/osteoporosis/bone-mass
* 1 2 2. Hye Young Jin. Low Bone Mineral Density in Children and Adolescents with Cancer [Internet]. US National Library of Medicine. 30 September 2020 [cited 18 August 2021]. Available From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7538298/
* 1 2 3. H M Frost. Wolff's Law and Bone's Structural Adaptations to Mechanical Usage: An Overview for Clinicians [Internet]. 1994 [cited 18 August 2021]. Available From: https://pubmed.ncbi.nlm.nih.gov/8060014/
* ↑ 4. Web Report. Insufficient Physical Activity [Internet]. Australian Institute of Health and Welfare. 20 October 2020 [cited 18 August 2021]. Available From: https://www.aihw.gov.au/reports/risk-factors/insufficient-physical-activity/contents/physical-inactivity
* 1 2 5. Lumen Learning. Physical Development During Exercise – Module 3: Physical Development [Internet]. Lumen Learning. 2019 [cited 18 August 2021]. Available From: https://courses.lumenlearning.com/atd-fscj-childpsychology/chapter/physical-development-during-adolescence/#:~:text=During%20puberty%2C%20both%20sexes%20experience,(i.e.%2C%20growth%20spurt).&text=Because%20rates%20of%20physical%20development,than%20their%20later%20maturing%20peers.
* ↑ 6. Web Report. The Health of Australia’s Females [Internet]. Australian Institute of Health and Welfare. 10 December 2019 [cited 18 August 2021]. Available From: https://www.aihw.gov.au/reports/men-women/female-health/contents/lifestyle-risk-factors/physical-activity
* 1 2 3 4 7. David L Nichols. David L Nichols Research Profile [Internet]. Research Gate. 2008 [cited 22 August 2021]. Available From: https://www.researchgate.net/scientific-contributions/David-L-Nichols-38468108
* 1 2 3 4 8. Charlotte F Sanborn. Charlotte F Sanborn Research Profile [Internet]. Research Gate. 2008 [cited 22 August 2021]. Available From: https://www.researchgate.net/scientific-contributions/Charlotte-F-Sanborn-2089752534
* 1 2 3 4 9. Anna Love. Anna Love Research Profile [Internet]. Research Gate. 2008 [cited 22 August 2021]. Available From: https://www.researchgate.net/scientific-contributions/Anna-Love-2076870802
* ↑ 10. Sundeep Khosla. Estrogen and the Skeleton [Internet]. US National Library of Medicine. November 2012 [cited 18 August 2021]. Available From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3424385/#:~:text=Direct%20estrogen%20effects%20on%20osteocytes,T%2Dcell%20regulation%20of%20osteoclasts.
* 1 2 3 4 5 6 7 8 9 11. David Nichols, PhD. Resistance Training and Bone Mineral Density in Adolescent Females [Internet]. The Journal of Pediatrics. October 2001 [cited 18 August 2021]. Available From: https://reader.elsevier.com/reader/sd/pii/S002234760157482X?token=3B2C55C757110053CCFA0A3CE8207133014206BBEF05484BA7767414F0CC389BDF0BCE1F6A72A982E36F8990A8D465BD&originRegion=us-east-1&originCreation=20210816062549
* ↑ 12. L. Burke. Dual X-Ray Absorptiometry (DXA) for Measurement of Body Composition in Athletes: Experiences That Underpin the Importance of Optimising the Reliability of Measurement [Internet]. Journal of Science and Medicine in Sport. September 2017 [cited 22 August 2021]. Available From: https://www.jsams.org/article/S1440-2440(17)31392-0/fulltext.
* ↑ 13. Nichols DL, Sanborn CF, BonnickSL, Ben-Ezra V, Gench B, DiMarcoNM. The effects of gymnastics train-ing on bone mineral density. Med SciSports Exerc 1994;26:1220-5.
* ↑ 14. Morris FL, Naughton GA, Gibbs JL,Carlson JS, Wark JD. Prospectiveten-month exercise intervention inpremenarcheal girls: positive effectson bone and lean mass. J Bone MinerRes 1997;12:1453-62
* ↑ 15. A Ram Hong. Effects of Resistance Training on Bone Health [Internet]. US National Library of Medicine: National Institutes of Health. December 2018 [cited 22 August 2021]. Available From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279907/
* ↑ 16. Social Psychology. The Egocentric Bias: Why It’s Hard to See Things from a Different Perspective [Internet]. Effectiviology. 2021 [cited 24 August 2021]. Available From: https://effectiviology.com/egocentric-bias/
* 1 2 3 4 17. Department of Health. Physical Activity and Exercise Guidelines for All Australians [Internet]. Australian Government. 7 May 2021 [cited 22 August 2021]. Available From: https://www.health.gov.au/health-topics/physical-activity-and-exercise/physical-activity-and-exercise-guidelines-for-all-australians