New research suggests skipping benefits both brains and bones.
In an ageing population, Alzheimer's and osteoporosis are two, seemingly unrelated, prominent health issues both with soaring diagnosis rates. Alzheimer's, affecting nearly 53 million individuals globally, is characterised by progressive cognitive decline, with loss of memory among the first symptoms reported. Osteoporosis is a condition affecting bone mass density, leaving the individual with an increased fracture risk, significantly impacting quality of life. Both diseases disproportionately affect women, with osteoporosis rates amplified post-menopause and females accounting for nearly two-thirds of Alzheimer's diagnoses. Surprisingly, there is mounting evidence of a complex interplay between the two conditions with recent research suggesting that improvements in bone mass density, not only reduce fracture rates but also act to improve memory and offset cognitive decline (1). Weight-bearing and plyometric exercises are widely known to impact bone density with numerous studies citing rope jumping - or skipping as we called it at school - as successful in increasing bone density (2). This post examines the research and asks if it is time we moved skipping out of the playgrounds and boxing gyms and into our daily routines?
Jump for your Bones
Far from being just scaffolding for the body, bone is a living tissue that is constantly adapting to reflect the stresses that are - or aren’t - put on it. Weight-bearing exercise - anything which makes you move against gravity - is key for maintaining bone health. For example, astronauts - without the continuous load of Earth's gravity - lose between 1% to 2% of bone density per month compared to 0.5% to 1% per year in post-menopausal individuals. This is due to a decrease in bone building activity while the reabsorption of old or damaged bone continues at a normal pace meaning that breakdown outstrips development (3). Back on earth and for women post-menopause, the loss of estrogen not only increases reabsorption but also slows down the formation of new bone (4).
Osteoblasts and osteoclasts are the cells responsible for bone growth and development. Osteoblasts form new bones and add growth to existing bone tissue. Osteoclasts dissolve old and damaged bone tissue so it can be replaced with new, healthier cells created by osteoblasts.
However, all is not lost, with research agreeing that across the lifespan, exercise acts positively on bone density. In childhood and adolescence, activity is shown to augment bone health with long-lasting benefits into adulthood. While age-related decline begins around 35 (5), weight-bearing exercise has been shown to maintain and even enhance bone density (1). Exposing your bones to a stressor creates an adaptive response where the muscles and tendons apply tension to the bones, stimulating the production of more tissue (6). Despite popular belief, weight lifting alone is not the most efficient way to strengthen bones. A study suggested combining weight training with other high-impact exercises creates a higher bone density than just weight lifting alone. However, when comparing weight-lifters to individuals who participated in non-weight-bearing exercises such as swimming or cycling, the weight lifters showed significantly higher bone density (7). Another study showed that premenopausal women who included skipping and weight lifting in their fitness program improved their spine density by about 2% compared to a control group, with both upper and lower body strength training considered the most beneficial (8).
Plyometric Exercise
"Plyometrics are exercises that require muscles to exert maximum force for brief periods of time to increase power (speed–strength). Jumping rope, jumping jacks, throwing, and catching a ball against a wall, and boxing with a punching bag are the most typical workouts" (9)
So why skipping? Researchers from the Bone & Joint Injury Prevention & Rehabilitation Center at the University of Michigan identified 3 properties of exercise that impact bone density; (10)
Strain magnitude: the force or impact of the exercise, for example in weightlifting
Strain rate: the rate of impact, jumping or plyometrics have a high strain rate
Strain frequency: the frequency of impact such as in running
Plyometrics are considered better than other weight-bearing exercises as they are of higher intensity with a larger magnitude and frequency. A good example of the power of plyometrics is in the difference between the playing and non-playing arm of racquet sports athletes, where the playing arm is not only stronger but with a greater bone density than the non-playing arm (11). Jump training exercises are associated with ground reaction forces of up to seven times body weight. When combined with the tensile forces applied by the muscles, these two factors create the best stimulus for the osteoblasts and osteoclasts - the bone cells used to reabsorb old tissue and make new bone (12).
A 2024 meta analysis of randomised controlled trials - the gold standard of research - found plyometrics to be a safe and time-efficient method to improve bone density in premenopausal people aged 18–65. The research also suggested that increasing training intensity also increased the effect. Furthermore, these effects lasted for several months after the study was complete (2). For those post menopause, the research is divided, with some studies showing an improvement other finding no difference (13). However it is key to note that control groups who didn't do any jumping exercises observed a bone density decrease. Therefore for individuals pre-menopause the advice would be skip to create and post menopause skip to maintain.
Jump for your Brain
While any aerobic exercise will increase blood flow to the brain by about 20-25%, research suggests that compression of the major arteries in the feet increases blood flow to the brain by a further 10-15%, boosting cognitive function. However, it isn’t this increased blood flow which is making waves in memory research. Bone is an endocrine gland and during the process of bone building, it releases a hormone called osteocalcin. Eric Kandel, a Nobel prize winner researching memory theorised a link between memory and levels of osteocalcin in the blood. Osteocalcin, his research suggests, feeds information to the brain, travelling via the blood to specialised receptors in the hippocampus, the brain area responsible for memory (14). Studies also show that without osteocalcin this brain-bone communication doesn’t happen, with a resultant effect of a smaller and less connected hippocampus and other brain regions (15). This led researchers to consider that the brain is affected by a lack of bone building. A 2023 study linked cognitive impairment to an increased risk of osteoporosis (16) and low levels of osteocalcin have been associated with Alzheimer's disease (17). Increasing osteocalcin levels is considered to improve cognitive dysfunction and is also suggested to have a protective effect on age-related cognitive decline (18). Although further research is needed, osteocalcin has been mooted as a potential therapeutic option for Alzheimer's, serving to reduce both the amyloid plaque and the impaired glucose metabolism associated with the disease (19).
Finally, an interesting point to note, for optimum memory enhancement research also suggests that varying the types of skipping exercise is key (for example, high knees, alternate legs, double bounce etc.) A study found that when compared to a uniform skipping style, those using a highly variable sequence performed better on arithmetic tasks, particularly memory retention tests. Importantly there was no statistical difference in heart rate (20).
Other studies also suggest benefits in working memory in children with ADHD (21); improvements in anxiety levels (22) and rates of depression (23). Psychological and skeletal advantages aside, other benefits of skipping are well-known and obvious. For the time-poor, cardiovascular-wise 10 minutes of skipping is the equivalent of 30 minutes jogging (24) and for an even more intense workout, weighted vests can be worn. Rope jumping is also low cost and requires very little room. In children and pre-menopausal adults, skipping can optimize bone density. In post-menopausal individuals, skipping may help mitigate the effects of estrogen and guard against bone loss. So much so, that the Royal Osteoporosis Society recommends 50 jumps a day to maintain bone density. However, the most exciting evidence is for the positive impact of plyometric exercise on cognitive function and memory. With such compelling benefits maybe we should all be reaching for our ropes.
To further understand how skipping and plyometric exercises can impact your customer or discuss any of the above please contact us or email hello@factoryforecasting.com
References
1. For overview see Karnik, S.J., Margetts, T.J., Wang, H.S. et al. Mind the Gap: Unraveling the Intricate Dance Between Alzheimer’s Disease and Related Dementias and Bone Health. Curr Osteoporos Rep 22, 165–176 (2024). https://doi.org/10.1007/s11914-023-00847-x
2. Rodricks, Nathan1,2; Deccy, Stephanie1,2; Saint Louis, Marc Edwin1,2; Quintero, Daniel3; Ramirez, Jose3; Paultre, Kristopher J.1,2,4,5. Effect of Plyometrics on Bone Mineral Density in Young Adults: A Systematic Review and Meta-Analysis. Translational Journal of the ACSM 9(1):e000242, Winter 2024. | DOI: 10.1249/TJX.0000000000000242
3. Guzman, A. (2024, March 21). Counteracting bone and muscle loss in microgravity - NASA. NASA. https://www.nasa.gov/missions/station/iss-research/counteracting-bone-and-muscle-loss-in-microgravity/
4. Väänänen, H. K., & Härkönen, P. L. (1996). Estrogen and bone metabolism. Maturitas, 23, S65–S69. https://doi.org/10.1016/0378-5122(96)01015-8
6. Kohrt, W. M., Bloomfield, S. A., Little, K. D., Nelson, M. E., & Yingling, V. R. (2004). Physical activity and bone health. Medicine & Science in Sports & Exercise, 36(11), 1985-1996.
7. Nikander R, Sievanen H, Heinonen A, et al: Femoral neck structure in adult female athletes subjected to different loading modalities. Journal of Bone and Mineral Research. 2005; 20(3): 520-528.
8. Winters-Stone KM, Snow CM. Site-specific response of bone to exercise in premenopausal women. Bone. 2006; 39(6): 1203-1209.
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11. Haapasalo H, Kannus P, Sievänen H, Pasanen M, Uusi-Rasi K, Heinonen A, Oja P, Vuori I. Effect of long-term unilateral activity on bone mineral density of female junior tennis players. J Bone Miner Res. 1998 Feb;13(2):310-9. doi: 10.1359/jbmr.1998.13.2.310. PMID: 9495526.
12. Gómez-Bruton, A., Matute-Llorente, Á., González-Agüero, A. et al. Plyometric exercise and bone health in children and adolescents: a systematic review. World J Pediatr 13, 112–121 (2017). https://doi.org/10.1007/s12519-016-0076-0
13. Vetrovsky T, Steffl M, Stastny P, Tufano JJ. The Efficacy and Safety of Lower-Limb Plyometric Training in Older Adults: A Systematic Review. Sports Med. 2019 Jan;49(1):113-131. doi: 10.1007/s40279-018-1018-x. PMID: 30387072; PMCID: PMC6349785.
14. Khrimian, L., Obri, A., Ramos-Brossier, M., Rousseaud, A., Moriceau, S., Nicot, A., Mera, P., Kosmidis, S., Karnavas, T., Saudou, F., Gao, X., Oury, F., Kandel, E., & Karsenty, G. (2017). Gpr158 mediates osteocalcin’s regulation of cognition. the Journal of Experimental Medicine/the Journal of Experimental Medicine, 214(10), 2859–2873. https://doi.org/10.1084/jem.20171320
15. Obri A, Khrimian L, Karsenty G, Oury F. Osteocalcin in the brain: from embryonic development to age-related decline in cognition. Nat Rev Endocrinol. 2018 Mar;14(3):174-182. doi: 10.1038/nrendo.2017.181. Epub 2018 Jan 29. PMID: 29376523; PMCID: PMC5958904.
16. Xie, C., Wang, C., & Luo, H. (2023). Increased risk of osteoporosis in patients with cognitive impairment: a systematic review and meta-analysis. BMC Geriatrics, 23(1). https://doi.org/10.1186/s12877-023-04548-z
17. Fehsel K, Christl J. Comorbidity of osteoporosis and Alzheimer’s disease: Is ‘AKT ‘-ing on cellular glucose uptake the missing link? Ageing Res Rev. 2022;76:101592.
18. Shan, C., Zhang, D., Ma, D., Hou, Y., Zhuang, Q., Gong, Y., Sun, L., Zhao, H., Tao, B., Yang, Y., Li, S., & Liu, J. (2023). Osteocalcin ameliorates cognitive dysfunctions in a mouse model of Alzheimer’s Disease by reducing amyloid β burden and upregulating glycolysis in neuroglia. Cell Death Discovery, 9(1). https://doi.org/10.1038/s41420-023-01343-y
19. Karnik, S.J., Margetts, T.J., Wang, H.S. et al. Mind the Gap: Unraveling the Intricate Dance Between Alzheimer’s Disease and Related Dementias and Bone Health. Curr Osteoporos Rep 22, 165–176 (2024). https://doi.org/10.1007/s11914-023-00847-x
20. Burdack J, Schöllhorn WI. Cognitive Enhancement through Differential Rope Skipping after Math Lesson. Int J Environ Res Public Health. 2022 Dec 23;20(1):205. doi: 10.3390/ijerph20010205. PMID: 36612527; PMCID: PMC9819879.
21. Huang, Z., Li, L., Lu, Y., Meng, J., & Wu, X. (2024). Effects of rope skipping exercise on working memory and cardiorespiratory fitness in children with attention deficit hyperactivity disorder. Frontiers in Psychiatry, 15. https://doi.org/10.3389/fpsyt.2024.1381403
22. Yamashita, Masatoshi, and Takanobu Yamamoto. 2021. "Impact of Long-Rope Jumping on Monoamine and Attention in Young Adults" Brain Sciences 11, no. 10: 1347. https://doi.org/10.3390/brainsci11101347
23. N. Jufril, H. Hardian, D. A. Indraswari, and E. Kumaidah, "The Effect of Jump Rope Training on Mood Among Senior High School Students," Jurnal Kedokteran Diponegoro (Diponegoro Medical Journal), vol. 11, no. 5, pp. 263-267, Sep. 2022. https://doi.org/10.14710/dmj.v11i5.35479
24. Baker, J. A. (1968). Comparison of Rope Skipping and Jogging as Methods of Improving Cardiovascular Efficiency of College Men. Research Quarterly. American Association for Health, Physical Education and Recreation, 39(2), 240–243. https://doi.org/10.1080/10671188.1968.10618043