Strengthening Skeletons With Age: The Bone-Boosting Benefits of Sprint and Impact Training
From facilitating movement and allowing us to stand upright without dissolving into a puddle on the floor to forming new blood cells, the 206 bones that make up the human skeleton perform a wide variety of functions that are vital to maintaining life as we know it. Our bones are constantly being remodeled — meaning, aged bone tissue is removed or resorbed, and new bone tissue takes its place to maintain skeletal integrity. Although this is a lifelong and ongoing process, the balance of bone remodeling changes as we grow older. These age-related alterations cause a loss of bone mineralization and density in older adults — eventually leading to the highly prevalent bone disease called osteoporosis.
However, new research out of Finland finds that older adults can prevent this typical bone deterioration by participating in regular strength and impact training, even well into their 80s. As the authors of this paper state, “If intense strength and impact training is maintained on a regular basis from midlife to late adulthood, it could attenuate the aging-related deterioration of bone structure and strength to ultimately reduce the risk of osteopenia [the precursor to osteoporosis] and osteoporosis.”
The Benefits of Bone-Bearing Exercise
As bones become more brittle with age, the skeletal system cannot fully support the body, leading to fractures, falls, and frailty, with decreased independence and quality of life. And, bone strength begins to decline earlier than most would imagine, dropping by about 1% per year beginning at age 40.
In our younger years, the bone is highly adaptable and responsive to exercise. It has been previously thought that aged adult bones don’t retain this plasticity, leading to osteoporotic decline. Many older adults — even ones who were highly active in their earlier life — cease or dwindle their exercise routines as they advance in age, whether from pain, fatigue, lack of mobility, or perceived inability, which can further the imbalance of bone remodeling.
It’s well-known that high-intensity exercises, like strength, jumping, and sprint training, are beneficial to maintaining bone health and remodeling. Known as weight-bearing or bone-bearing exercise, these activities put additional stress on the bones. Although this sounds detrimental, the added stress actually helps bones to stimulate calcium deposition and encourage bone-forming cells to create more, resulting in stronger and denser bones.
A Longitudinal Look at Bone Health
Despite this knowledge of bone-bearing exercise’s benefits, there have not been any long-term studies that look at whether or not these activities can mitigate the age-related bone loss that leads to osteoporosis. In this study, Suominen and colleagues followed several aspects of bone health in a group of 69 male adults over 10 years. The men, who ranged in age from 40 to 85, were previous or current sprint athletes with long-term training and background in national sprint competitions.
At the beginning of the 10-year follow-up period, all of the men were actively training and competing. To tease out the differences between those who maintained their exercise habits as they aged, the research team split them into two groups. First, the “well-trained” men were actively competing and undergoing two or more strength, sprint, or impact training sessions per week within the last year of the study. The second group, the “less-trained” men, were retired from sprint competing and were solely doing endurance exercises, or none at all.
The researchers split the groups this way because it’s thought that sprint training, which combines running, jumping, and strength exercises, provides the strongest foundation for maintaining bone mass and structural integrity with age.
Sprinting Their Way to Stronger Bones
Suominen and colleagues measured bone properties by computed tomography (CT scans, or computerized x-rays), looking primarily at the tibia. Also known as the shinbone, the tibia is often studied in exercise research because it shows a typical decline in strength with age.
At the end of the 10-year follow-up period, the well-trained group exhibited significantly higher levels of bone mineral content and density in their tibial bones. While the well-trained men maintained these bone measurements over 10 years, the less-trained showed losses of tibial bone mineral content, density, and compressive bone strength index, ranging from -3-6%.
The researchers also split the well-trained men into two age groups, finding that men aged 65 to 85 had more pronounced structural improvements in their tibial bones. This suggests that the continued strength and sprint training may be more effective for preserving bone in older age, compared to the middle-aged men in the 40- to 64-year-old group.
In all of the well-trained men, the beneficial effects of training were most pronounced in the trabecular bone — the light, porous, spongy bone that gives bones their honeycombed appearance. As the primary function of trabecular bone is to provide strength and transfer the load away from the joints, it makes sense that impact training would strengthen or maintain this part of the bone.
The researchers speculate that not only does this type of training benefit bones directly, but it also further strengthens bones from the effects of training on increasing muscle mass and power through complex muscle-bone interactions.
Staying Strong Through the Decades
Normal aging can create limitations on training and exercise tolerance, including reduced mobility and recovery, leading many older adults to perceive themselves as unable to maintain their training intensity. However, the researchers urge the continuation of strength, impact, or sprint training with age, as this study finds it can prevent bone deterioration and, with it, reduce the risk of osteoporosis. This research also supports the theory of aging bones retaining their adaptability and plasticity, highlighting the importance of regular, intensive training for maintaining bone health.
"Although the intensive training of the athletes as such is not possible for all aging people, strength and power training is highly recommended at all ages, regardless of the functional status," Suominen says. "In the present study, the benefits of high-impact training were most evident among middle-aged while strength training may be effective in preserving bone in older populations. Muscle strength and power are highly important also in preventing falls and related fractures."
Suominen, T.H., et al. (2021) Regular Strength and Sprint Training Counteracts Bone Aging: A 10-Year Follow-Up in Male Masters Athletes. Journal of Bone and Mineral Research. doi.org/10.1002/jbm4.10513.