Aged bone displays an increased responsiveness to low-intensity resistance exercise

Buhl, Kathleen M.; Jacobs, Christopher R.; Turner, Russell T.; Evans, Glenda L.; Farrell, Peter A.; Donahue, Henry J.

doi:10.1152/jappl.2001.90.4.1359

Cited by 48 publications

(37 citation statements)

References 34 publications

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“…In a recent study, we observed that tibial compression stimulated equal or greater cortical bone responses in 22-month old BALB/c mice compared to 7-month old mice [12]. Moreover, several (though not all [2], [3]) exercise studies in rodents reported that the skeletal benefits of exercise are not limited by age [4], [5], [6], [7], [8]. For example, 12 weeks of daily treadmill running [8] and 8 weeks of daily jumping [5] each produced significant increases in bone mass in 2-year old rats.…”

Section: Discussionmentioning

confidence: 92%

“…Exercise studies of young and aged rodents have demonstrated either reduced responsiveness in aged animals [2], [3], no difference between ages [4], [5], [6], or enhanced responsiveness in aged animals [7], [8]. Several studies that used extrinsic loading (e.g., tibial bending) reported reduced cortical responsiveness in aged turkeys [9], rats [10] and mice [11] compared to younger animals.…”

Section: Introductionmentioning

confidence: 99%

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Tibial Loading Increases Osteogenic Gene Expression and Cortical Bone Volume in Mature and Middle-Aged Mice

et al. 2012

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There are conflicting data on whether age reduces the response of the skeleton to mechanical stimuli. We examined this question in female BALB/c mice of different ages, ranging from young to middle-aged (2, 4, 7, 12 months). We first assessed markers of bone turnover in control (non-loaded) mice. Serum osteocalcin and CTX declined significantly from 2 to 4 months (p<0.001). There were similar age-related declines in tibial mRNA expression of osteoblast- and osteoclast-related genes, most notably in late osteoblast/matrix genes. For example, Col1a1 expression declined 90% from 2 to 7 months (p<0.001). We then assessed tibial responses to mechanical loading using age-specific forces to produce similar peak strains (−1300 µε endocortical; −2350 µε periosteal). Axial tibial compression was applied to the right leg for 60 cycles/day on alternate days for 1 or 6 weeks. qPCR after 1 week revealed no effect of loading in young (2-month) mice, but significant increases in osteoblast/matrix genes in older mice. For example, in 12-month old mice Col1a1 was increased 6-fold in loaded tibias vs. controls (p = 0.001). In vivo microCT after 6 weeks revealed that loaded tibias in each age group had greater cortical bone volume (BV) than contralateral control tibias (p<0.05), due to relative periosteal expansion. The loading-induced increase in cortical BV was greatest in 4-month old mice (+13%; p<0.05 vs. other ages). In summary, non-loaded female BALB/c mice exhibit an age-related decline in measures related to bone formation. Yet when subjected to tibial compression, mice from 2–12 months have an increase in cortical bone volume. Older mice respond with an upregulation of osteoblast/matrix genes, which increase to levels comparable to young mice. We conclude that mechanical loading of the tibia is anabolic for cortical bone in young and middle-aged female BALB/c mice.

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Tibial Loading Increases Osteogenic Gene Expression and Cortical Bone Volume in Mature and Middle-Aged Mice

et al. 2012

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“…It is still controversial whether the responsiveness of the aged skeleton to mechanical loading is altered. It has been reported that the responsiveness of the aged skeleton is increased [17,18] , reduced [19,20] or unaffected [21,22] compared with the younger skeleton. Therefore, it is unclear whether reduced mechanoresponsiveness is involved in age-related bone loss.…”

Section: Discussionmentioning

confidence: 99%

Interaction between Exercise, Dietary Restriction and Age-Related Bone Loss in a Rodent Model of Male Senile Osteoporosis

et al. 2011

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Background: The pathophysiology of age-related bone loss and whether age-related bone loss can be prevented by exercise are still a matter of debate. Objective: It was the aim of this study to investigate the long-term effects of exercise and mild food restriction on bone mineral density (BMD) and bone geometry in the appendicular skeleton of aging male rats. Methods: Male Sprague-Dawley rats were studied from 5 to 23 months of age. The rats were divided into 4 groups: baseline, free access to food and running wheels (RW), fed to pair weight with the RW group (PW) and sedentary control animals with free access to food (SED). All rats were housed individually. Volumetric BMD and geometry of femurs and tibiae were assessed by peripheral quantitative computed tomography (pQCT). In addition, the tibial shafts were analyzed by cortical bone histomorphometry. Results: At the end of the experiment, RW and PW rats had similar body weight. The body weight of SED rats was 31% greater than that of RW rats. pQCT analysis of femurs and tibiae as well as histomorphometric analysis of the tibial shafts showed that dietary restriction resulted in an enlargement of the marrow cavity and cortical thinning at the femoral and tibial shafts relative to the RW and SED groups. Voluntary running exercise provided no additional protection against age-related bone loss when compared with the 31% heavier SED control rats. Neither exercise nor increased body weight in SED animals could completely prevent age-related bone loss between 19 and 23 months of age. Conclusion: We conclude that dietary restriction had clear negative effects on BMD and bone geometry and that running wheel exercise provided partial protection but could not prevent age-related bone loss.

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“…To our knowledge, however, no published studies have been designed to assess the effects of two intensities of jump RE on weight-bearing cancellous bone. Additionally, there are very limited data about changes in cancellous bone remodeling, microarchitecture, and mechanical properties in skeletally mature animals with voluntary jump RE (3,37).…”

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confidence: 99%

Increased training loads do not magnify cancellous bone gains with rodent jump resistance exercise

Swift

Gasier²,

Swift

et al. 2010

Journal of Applied Physiology

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This study sought to elucidate the effects of a low- and high-load jump resistance exercise (RE) training protocol on cancellous bone of the proximal tibia metaphysis (PTM) and femoral neck (FN). Sprague-Dawley rats (male, 6 mo old) were randomly assigned to high-load RE (HRE; n = 16), low-load RE (LRE; n = 15), or sedentary cage control (CC; n = 11) groups. Animals in the HRE and LRE groups performed 15 sessions of jump RE during 5 wk of training. PTM cancellous volumetric bone mineral density (vBMD), assessed by in vivo peripheral quantitative computed tomography scans, significantly increased in both exercise groups (+9%; P < 0.001), resulting in part from 130% (HRE; P = 0.003) and 213% (LRE; P < 0.0001) greater bone formation (measured by standard histomorphometry) vs. CC. Additionally, mineralizing surface (%MS/BS) and mineral apposition rate were higher (50-90%) in HRE and LRE animals compared with controls. PTM bone microarchitecture was enhanced with LRE, resulting in greater trabecular thickness (P = 0.03) and bone volume fraction (BV/TV; P = 0.04) vs. CC. Resorption surface was reduced by nearly 50% in both exercise paradigms. Increased PTM bone mass in the LRE group translated into a 161% greater elastic modulus (P = 0.04) vs. CC. LRE and HRE increased FN vBMD (10%; P < 0.0001) and bone mineral content (∼ 20%; P < 0.0001) and resulted in significantly greater FN strength vs. CC. For the vast majority of variables, there was no difference in the cancellous bone response between the two exercise groups, although LRE resulted in significantly greater body mass accrual and bone formation response. These results suggest that jumping at minimal resistance provides a similar anabolic stimulus to cancellous bone as jumping at loads exceeding body mass.

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Aged bone displays an increased responsiveness to low-intensity resistance exercise

Cited by 48 publications

References 34 publications

Tibial Loading Increases Osteogenic Gene Expression and Cortical Bone Volume in Mature and Middle-Aged Mice

Tibial Loading Increases Osteogenic Gene Expression and Cortical Bone Volume in Mature and Middle-Aged Mice

Interaction between Exercise, Dietary Restriction and Age-Related Bone Loss in a Rodent Model of Male Senile Osteoporosis

Increased training loads do not magnify cancellous bone gains with rodent jump resistance exercise

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