Does weight-bearing exercise protect against the effects of exercise-induced oligomenorrhea on bone density?

1996 ◽  
Vol 6 (6) ◽  
pp. 448-452 ◽  
Author(s):  
G. Pearce ◽  
S. Bass ◽  
N. Young ◽  
C. Formica ◽  
E. Seeman
Keyword(s):  
Bone Density ◽  
Weight Bearing ◽  
Exercise Induced

Effect of unweighting on skeletal muscle use during exercise

1995 ◽  
Vol 79 (1) ◽  
pp. 168-175 ◽  
Author(s):  
L. L. Ploutz-Snyder ◽  
P. A. Tesch ◽  
D. J. Crittenden ◽  
G. A. Dudley
Keyword(s):  
Lower Limb ◽  
Weight Bearing ◽  
Muscle Group ◽  
Mr Images ◽  
Cross Sectional ◽  
Quadriceps Femoris Muscle ◽  
Before And After ◽  
Exercise Induced ◽  
The Right ◽  
Femoris Muscle

Exercise-induced spin-spin relaxation time (T2) shifts in magnetic resonance (MR) images were used to test the hypothesis that more muscle would be used to perform a given submaximal task after 5 wk of unweighting. Before and after unilateral lower limb suspension (ULLS), 7 subjects performed 5 sets of 10 unilateral concentric actions with the quadriceps femoris muscle group (QF) at each of 4 loads: 25, 40, 55, and 70% of maximum. T2-weighted MR images of the thigh were collected at rest and after each relative load. ULLS elicited a 20% decrease in strength of the left unweighted QF and a 14% decrease in average cross-sectional area (CSA) with no changes in the right weight-bearing QF. Average CSA of the left or right QF showing exercise-induced T2 shift increased as a function of exercise intensity both before and after ULLS. On average, 12 +/- 1, 15 +/- 2, 18 +/- 2, and 22 +/- 1 cm2 of either QF showed elevated T2 for the 25, 40, 55, and 70% loads, respectively, before ULLS. Average CSA of the left but not the right QF, showing elevated T2 after ULLS, was increased to 16 +/- 2, 23 +/- 3, 31 +/- 7, and 39 +/- 5 cm2, respectively. The results indicated that unweighting increased exercise-induced T2 shift in MR images, presumably due to greater muscle mass involvement in exercise after than before unweighting, suggesting a change in motor control.

scholarly journals Assessment of First Metatarsal Head Bone Density for Optimal Screw Placement in Minimally-Invasive Hallux Valgus Surgery

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0003
Author(s):  
Katherine M. Dederer ◽  
Patrick J. Maloney ◽  
John T. Campbell ◽  
Clifford L. Jeng ◽  
Rebecca A. Cerrato
Keyword(s):  
Bone Density ◽  
Minimally Invasive ◽  
Hallux Valgus ◽  
Screw Fixation ◽  
Weight Bearing ◽  
Metatarsal Head ◽  
Screw Placement ◽  
Cannulated Screws ◽  
First Metatarsal ◽  
History Of

Category: Bunion; Basic Sciences/Biologics Introduction/Purpose: Minimally-invasive surgery (MIS) for hallux valgus correction has become increasingly common. This technique involves an osteotomy of the first metatarsal, followed by fixation with two cannulated screws. Since screws are typically not bicortical, they rely upon bone quality within the metatarsal head for fixation strength. However, bone mineral density (BMD) within different regions of the metatarsal head is unknown. Measuring the BMD in the target region may predict the strength of the bone-screw fixation. Similar to previous work which determined the optimal position for lag screw placement in the femoral head during hip fracture fixation, this study aimed to determine average BMD within four quadrants of the metatarsal head using CT and thus predict the optimal trajectories for cannulated screws during the MIS bunion procedure. Methods: All patients between 18-75 years of age scheduled to undergo MIS hallux valgus correction by one of two surgeons experienced in the MIS technique were eligible to participate. Patients were excluded if they had a prior first metatarsal surgery, pre-existing hardware, previous first metatarsal fracture, or a history of osteoporosis treatment. Patients were enrolled prospectively, and a weight-bearing CT scan of the affected foot was obtained pre-operatively. Demographic factors including age, sex, laterality, body mass index (BMI), comorbidities, and smoking status as well as standard three-view weight-bearing radiographs were collected for all patients.Using the coronal CT slice at maximal metatarsal head diameter, each head was divided into equal quadrants. Hounsfield units (HU) within each quadrant were measured independently by three study investigators using our hospital’s radiology viewing software (Merge PACS; IBM Corporation, Armonk, NY), and these density measurements were averaged. Statistical analysis was conducted using ANOVA and Student’s t-test. Results: Fifteen patients were included for preliminary analysis. All patients were female. The average age was 45.7 years. 9 of the 15 included feet were right feet. Average BMI was 28.0. One patient reported active smoking prior to surgery. Comorbidities included obesity in three patients; none were diabetic. One had a history of diplegic cerebral palsy. The average HVA on a weight- bearing AP foot x-ray was 28.2°, and the average IMA was 12.6°. The BMD within the metatarsal head varied by quadrant, with the two combined dorsal quadrants having higher average BMD than the two combined plantar quadrants (122 vs 85 HU; p<0.001). The dorsal lateral quadrant had the highest average BMD of any quadrant (132 HU, p<0.001; Table 1). Conclusion: The density of the metatarsal head did vary by region within the head. The highest BMD was found in the dorsal lateral quadrant, and the lowest in the plantar lateral and plantar medial quadrants, which did not differ significantly from each other. Because strength of screw fixation is predicated upon screw design as well as bone density, these results suggest that surgeons may wish to direct screws toward the dorsolateral region of the metatarsal head in order to achieve optimal fixation. Further work is needed to determine whether this varies with patient age, gender, or hallux valgus angle. [Table: see text]

scholarly journals The Effectiveness of Physical Exercise on Bone Density in Osteoporotic Patients

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Maria Grazia Benedetti ◽  
Giulia Furlini ◽  
Alessandro Zati ◽  
Giulia Letizia Mauro
Keyword(s):  
Bone Density ◽  
Physical Exercise ◽  
Bone Mass ◽  
Weight Bearing ◽  
Reaction Force ◽  
Whole Body Vibration ◽  
Whole Body ◽  
Body Vibration ◽  
Body Regions ◽  
Resistance Exercises

Physical exercise is considered an effective means to stimulate bone osteogenesis in osteoporotic patients. The authors reviewed the current literature to define the most appropriate features of exercise for increasing bone density in osteoporotic patients. Two types emerged: (1) weight-bearing aerobic exercises, i.e., walking, stair climbing, jogging, and Tai Chi. Walking alone did not appear to improve bone mass; however it is able to limit its progressive loss. In fact, in order for the weight-bearing exercises to be effective, they must reach the mechanical intensity useful to determine an important ground reaction force. (2) Strength and resistance exercises: these are carried out with loading (lifting weights) or without (swimming, cycling). For this type of exercise to be effective a joint reaction force superior to common daily activity with sensitive muscle strengthening must be determined. These exercises appear extremely site-specific, able to increase muscle mass and BMD only in the stimulated body regions. Other suggested protocols are multicomponent exercises and whole body vibration. Multicomponent exercises consist of a combination of different methods (aerobics, strengthening, progressive resistance, balancing, and dancing) aimed at increasing or preserving bone mass. These exercises seem particularly indicated in deteriorating elderly patients, often not able to perform exercises of pure reinforcement. However, for these protocols to be effective they must always contain a proportion of strengthening and resistance exercises. Given the variability of the protocols and outcome measures, the results of these methods are difficult to quantify. Training with whole body vibration (WBV): these exercises are performed with dedicated devices, and while it seems they have effect on enhancing muscle strength, controversial findings on improvement of BMD were reported. WBV seems to provide good results, especially in improving balance and reducing the risk of falling; in this, WBV appears more efficient than simply walking. Nevertheless, contraindications typical of senility should be taken into account.

Mechanisms of bone remodeling during weight-bearing exercise

2006 ◽  
Vol 31 (6) ◽  
pp. 655-660 ◽  
Author(s):  
Ronald Zernicke ◽  
Christopher MacKay ◽  
Caeley Lorincz
Keyword(s):  
Mechanical Loading ◽  
Bone Structure ◽  
Weight Bearing ◽  
Bone Cell ◽  
Bone Adaptation ◽  
Bone Modeling ◽  
Extrinsic Factors ◽  
Paracrine Factors ◽  
Loading Effects ◽  
Exercise Induced

Exercise-induced mechanical loading can have potent effects on skeletal form and health. Both intrinsic and extrinsic factors contribute to bone structure and function. Mechanical simuli (e.g., strain magnitude, frequency, rate, and gradients, as well as fluid flow and shear stress) have potent influences on bone-cell cytoskeleton and associated signalling pathways. Although the immature skeleton may be more able to benefit from exercise, a skeletally mature population can also benefit from exercise programs aimed at increasing the functional loads to which the skeleton is exposed. The definitive explanation of mechanical-loading and (or) bone-cell mechanotransductive phenomena, however, remains elusive. Here, we briefly review the structural and anatomical foundation for bone adaptation, focusing on mechanical loading effects on bone, linked to the roles of integrins, cytoskeleton, membrane channels, and auto- and paracrine factors in bone modeling and remodeling.

Acceleration slope of exercise-induced impacts is a determinant of changes in bone density

2007 ◽  
Vol 40 (13) ◽  
pp. 2967-2974 ◽  
Author(s):  
Riikka Heikkinen ◽  
Erkki Vihriälä ◽  
Aki Vainionpää ◽  
Raija Korpelainen ◽  
Timo Jämsä
Keyword(s):  
Bone Density ◽  
Exercise Induced

scholarly journals Comparison of Tibial and Talar Bone Density as a Function of Resection Level in Patients Undergoing Total Ankle Replacement vs Demographic-Matched Controls

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0020
Author(s):  
Thos Harnroongroj ◽  
Lauren Volpert ◽  
Daniel Sturnick ◽  
Carolyn Sofka ◽  
Scott J. Ellis ◽  
...  
Keyword(s):  
Bone Density ◽  
Articular Surface ◽  
Weight Bearing ◽  
Total Ankle Replacement ◽  
Control Group ◽  
Ankle Arthritis ◽  
Relative Level ◽  
Percentage Decrease ◽  
Ankle Replacement ◽  
Significant Difference

Category: Ankle Arthritis Introduction/Purpose: Initial implant fixation is critical for long-term success of total ankle replacement (TAR). One important factor which contributes to implant stability is the quality of the surrounding bone. Previous studies characterized a decrease in bone density with increasing distance from the level of the joint in the tibia and talus in non-arthritic ankles. However, ankle arthritis affects bone density remains unclear. The objective of this study is to compare the bone density in patients with and without ankle arthritis as a function of resection level from the joint. We hypothesized that there would be no difference in bone densities at each resection level between groups and bone density would decrease with greater distance from articular surface in both groups. Methods: We retrospectively reviewed 93 end-stage ankle arthritis patients with available preoperative non-weight bearing ankle computed tomography scans (CT)(Group A) and identified another cohort of 83 patients with non-arthritic ankles as a demographic-matched control group(Group B). Patients with retained ankle hardware, history of osteomyelitis, osteoporosis, and cysts greater than 1 cm in diameter at the ankle were excluded. There was no difference in term of gender, age and body mass index (BMI) between the groups(Table 1). The ROI tool in Sectra IDS7 picture archiving and communication system (PACS) was used to calculate Hounsfield Unit (HU) values in the cancellous region of the tibia and talus around the ankle joint. Measurements were obtained on axial CTs from 6 mm to 12 mm above the distal tibial plafond, and from 1 mm to 4 mm below the talar dome. The HU measurements and percentage decrease of HU values at each level were compared between groups. Results: Patients with ankle arthritis demonstrated significantly greater bone density than the control group between 6 mm and 10 mm from the joint in the tibia. There was no significant difference in bone density between 10 mm and 12 mm from the joint on the tibia, and at all levels in the talus between groups (Table 1). In both groups, bone density decreased significantly at each successive level from the joint for the tibia and talus. In addition, the percentage decrease of HU values at each relative level was the same in both groups. Conclusion: Patients with ankle arthritis demonstrated greater bone density at 6 mm to 10 mm from the joint in the tibia compared to demographic-matched controls. The increased bone density close to the joint may stem from bone eburnation that occurs as part of the arthritic process. In TAR, a tibial bone resection between 6 mm and 10 mm may provide improved initial stability of the implant. Contrary to traditional thinking, fixation into the talus may be of less concern.

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