On 20. January 36. Scientific Day of Osteoporosis Research and Information Group (GRIO) in Paris. This was an opportunity to remind people that physical activity has a significant impact on building and maintaining bone mass. We all know the calls of health authorities for regular physical activity and their benefits.But what do we know in 2023 about the role regular physical activity plays in our bone health?
Dr. Laurence Vico from the French National Institute of Health and Medical Research (INSERM) presented an overview of non-drug osteoporosis therapy at the event.
Some sports are better for the bones than others. Physical activities are associated with certain forces acting on the bone. Examples include weightlifting (3 to 7 times body weight), jumping (2 to 8 times body weight), running (1.5 to 3 times body weight) and walking (1 times body weight). These mechanical loads stimulate the osteoblasts and thus promote bone remodeling.
In contrast, sports without shock load-_– for example, cycling and swimming – are less osteogenic and therefore much less beneficial for bone formation.So nothing new here – except that the latest scientific data is not so clear-cut. They show that in swimmers, especially in their upper limbs, an increase in bone mass can occur.
The researchers were particularly interested in sports such as tennis and baseball, where one arm or leg is more stressed than the other. The reason for this is that the less active limb can be used as an internal control for the more active limb. In addition, differences in bone density between the two sides were found in tennis players in the area of the cortical cortex of the humerus.
Physical activity in adolescence increases the likelihood of having healthier bones later in life.In view of biomechanical studies, this makes sense. «They’re all pointing in the same direction,» Vico said. Intense physical activity during the peripubertal phase provides a lasting benefit in terms of bone geometric parameters. A computer simulation of the bone remodeling process has shown that the onset of osteoporosis is reduced by 13 years when area-related bone mineral density in young adults is 10 % above the mean.
Prepuberty and the early stages of puberty represent the phases that are now considered the window of opportunity to increase maximum bone mass. However, bone size is known to be more important than bone mineral density (CMD).
However, most available studies still deal with the KMD. For example, a meta-analysis of 22 Studies conducted in children and adolescents representing all Tanner stages (stage 1 to stage 4).The movement interventions included games, dance, resistance training and jumping exercises. All studies with early pubertal children, six with prepubertal children and two with pubertal children reported positive effects of exercise on bones. Compared to controls, the mean increase in bone parameters in prepubertal children was over 6-_ months 0.9–4.9 %, in early pubertal children 1.1–5.5 % and in pubertal children 0.3–1.9 % (p <0.05).
A previous study with female tennis and squash players showed that physical activity during the years of puberty is essential for maximizing bone mass. Although the potential for movement-induced bone gain is generally present in adults, the benefit in women is about twice as high when they start their training during or before menarche (lateral difference of humerus: 17–24 %) than after menarche (8–14 %).
Further evidence of exercise’s benefits for bone health suggests that practicing exercise over a long period of time helps increase CMD in later years.
For example, a retrospective study aimed to determine the long-term effect of exercise on CMD, bone mineral content (CMM) and body composition in 48 postmenopausal women (54–73 years).Half (24) of the women had been top athletes in their youth. All had a long (> 20 years) training and performance history. One half consisted of swimmers and the other half of runners. They were compared with 24-sedentary control subjects. At the time of this study, there were no significant differences in activity levels between female athletes and controls.
KMD and CMM did not differ significantly between the athletes, but were significantly higher in the female athletes than in the controls. The researchers concluded that physical activity during adolescence appears to have a beneficial effect on bone mass and helps prevent age-related bone loss.
Today it is clear that the microarchitecture of trabecular and cortical bone parts is reinforced by the mechanical stress of physical exercise, but in different ways.»The results of a study published in the year 2020 support the previous results and show that these two types of bones – trabecularly and cortical – do not behave in the same way,» Vico explained.
«These researchers found that, compared to the controls, trabecular KMD is higher in all athletes, regardless of the sports performed—in this case, cricket, running, swimming, and hockey. There are no serious differences between different sports groups. But this does not apply to the corticals,» explained Vico. «The results of the study suggest that hypertrophy of cortical in the middle shaft is associated with shock loads, while trabecular__- KMD is positively associated with shock and non-impact loads. That is, depending on the bone compartment, the adaptations are different …Cortical bone parts require discontinuous rather than continuous shock loads, from unusual directions and with sufficient force to produce a stimulus. As far as trabecular bone parts are concerned, we still do not know what kind of signal can reach and stimulate the bone cells, especially the osteoblasts.»
Regarding bone adaptation in athletes who stop or resume their athletic activities, a study with baseball pitchers found that the density-weighted polar moment of inertia (which indicates the torsional strength of a bone) and the thickness of the cortical at the level of the humerus were greater in their sport-continuing pitchers than in former pitchers. On the other hand, there were no significant differences in anything related to the trabecular bone portion and even the CMM.
«Due to a different thickness of the corticalis, those who continue their sport benefit from the biomechanical properties,» Vico said.»It should also be noted that the more these properties are developed, the higher the breaking strength of the bone. Therefore, it turns out that the CMD, which has always been the focus of attention, is not sufficient to assess the adaptation of the bone to mechanical stimuli».
This article was originally published on derFrench edition of Medscape.
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