"To stimulate the osteogenic effects for bone mass accretion, bone tissues must be exposed to mechanical load exceeding those experienced during daily living activities." "Runners, both male and female, have approximately 40% more bone mineral than matched controls."

In the tension between my enjoyment of rowing and running, I have routinely reminded myself that because the latter is a weight-bearing activity, it would help my bone mineral density (BMD). But it turns out that this may not be entirely true.

My adventure started with an article in Forbes Health, "Average Bench Press By Age, Weight, And Gender," which made several discomfiting assertions. The first was "According to the U.S. Bureau of Labor Statistics (BLS), 8.9 percent of people aged 15 and older engaged in weightlifting from 2011 to 2015." Given the importance of weight-bearing activities in preventing osteoporosis and sarcopenia, this is a surprising result. An article in the Journal of Endocrinology and Metabolism (1) is blunt: "To stimulate the osteogenic effects for bone mass accretion, bone tissues must be exposed to mechanical load exceeding those experienced during daily living activities." The data presented by the BLS is interesting. 86% of participants in aerobics, as opposed to activities like running, cycling, or walking, were women. 85.2% of yoga participants were women. These exercise modalities do little or nothing for osteoporosis as they do not load the musculoskeletal system. I did note with interest that rates of sarcopenia are approximately the same for men and women. (2) But given the BLS finding that only 18% of Americans engage in any sport or activity on a given day, it is not surprising to see elevated rates of frailty and sarcopenia in older people.

Further, in the BLS data, I noted that 60.8% of runners are male. I comforted myself that running doubtlessly contributed to my BMD, at least in my legs and lower spine. This turns out to be only partially true. One study reports that "runners, both male and female, have approximately 40% more bone mineral than matched controls." It also reports no increase in osteoarthritis in runners, dealing a blow to that myth. (3) But the picture becomes more ambiguous when total weekly mileage is considered. According to another study, BMD is highest in male runners who train 15 to 20 miles weekly. (4) Beyond this distance, BMD tends to decrease to the point where runners training 60 to 75 miles per week match the controls. (4) But other influences may be at play here. Runners in the highest weekly volume categories are more likely to be more competitive. Body weight becomes an issue for both male and female competitive runners. The decreasing BMD may be due to restrictive dietary factors for such athletes. In any event, this challenges my presumption that running is intrinsically better than rowing when the goal is to maximize BMD. 

One additional factor regarding bipedal exercise should be noted. Apparently, long-term brisk walking 3 or more times a week is beneficial for preventing BMD decreases in premenopausal women. (5) 

Anyone who knows me knows of my commitment to strength training. I came across a meta-analysis finding that any amount of resistance training reduced cardiovascular disease mortality by 19%, cancer mortality by 14%, and all-cause mortality by 15%. Interestingly, a maximum risk reduction of 27% was achieved around 60 minutes of strength training per week. (

(1) Hong, A. R., & Kim, S. W. (2018). Effects of Resistance Exercise on Bone Health. Endocrinology and metabolism (Seoul, Korea)33(4), 435–444. https://doi.org/10.3803/EnM.2018.33.4.435. Downloaded from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279907/ 

(2) Tay, L., Ding, Y. Y., Leung, B. P., Ismail, N. H., Yeo, A., Yew, S., Tay, K. S., Tan, C. H., & Chong, M. S. (2015). Sex-specific differences in risk factors for sarcopenia amongst community-dwelling older adults. Age (Dordrecht, Netherlands)37(6), 121. https://doi.org/10.1007/s11357-015-9860-3. Downloaded from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5005859/

(3) Lane NEBloch DAJones HHMarshall WHWood PDFries JF. Long-Distance Running, Bone Density, and Osteoarthritis. JAMA. 1986;255(9):1147–1151. doi:10.1001/jama.1986.03370090069022. Downloaded from:  https://jamanetwork.com/journals/jama/article-abstract/403118

(4) J. D. MacDougallC. E. WebberJ. MartinS. OrmerodA. ChesleyE. V. YounglaiC. L. Gordon, and C. J. Blimkie, Relationship among running mileage, bone density, and serum testosterone in male runnersJournal of Applied Physiology 1992 73:31165-1170. Downloaded from: https://journals.physiology.org/doi/abs/10.1152/jappl.1992.73.3.1165

(5) Lan, Y. S., & Feng, Y. J. (2022). The volume of brisk walking is the key determinant of BMD improvement in premenopausal women. PloS one17(3), e0265250. https://doi.org/10.1371/journal.pone.0265250. Downloaded from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8926180/

(6) Bennie, J. A., De Cocker, K., Teychenne, M. J., Brown, W. J., & Biddle, S. J. H. (2019). The epidemiology of aerobic physical activity and muscle-strengthening activity guideline adherence among 383,928 U.S. adults. The international journal of behavioral nutrition and physical activity16(1), 34. https://doi.org/10.1186/s12966-019-0797-2. Downloaded from: https://www.ajpmonline.org/article/S0749-3797(22)00176-3/fulltexthttps://www.ajpmonline.org/article/S0749-3797(22)00176-3/fulltext

 

Other references:

https://exrx.net/Testing/WeightLifting/StrengthStandards

Slowing bone loss with weight-bearing exercise, Harvard Health Publishing, April 11, 2021. Downloaded from https://www.health.harvard.edu/staying-healthy/slowing-bone-loss-with-weight-bearing-exercise.