Anabolic Bone Stimulus Requires a Pre-Exercise Meal and 45-Minute Walking Impulse of Suprathreshold Speed-Enhanced Momentum to Prevent or Mitigate Postmenopausal Osteoporosis within Circadian Constraints

Osteoporosis currently afflicts 8 million postmenopausal women in the US, increasing the risk of bone fractures and morbidity, and reducing overall quality of life. We sought to define moderate exercise protocols that can prevent postmenopausal osteoporosis. Our previous findings singled out higher walking speed and pre-exercise meals as necessary for suppression of bone resorption and increasing of markers of bone formation. Since both studies were amenable to alternate biomechanical, nutritional, and circadian interpretations, we sought to determine the relative importance of higher speed, momentum, speed-enhanced load, duration of impulse, and meal timing on osteogenic response. We hypothesized that: (1) 20 min of exercise one hour after eating is sufficient to suppress bone resorption as much as a 40-min impulse and that two 20 min exercise bouts separated by 7 h would double the anabolic effect; (2) early morning exercise performed after eating will be as effective as mid-day exercise for anabolic outcome; and (3) the 08:00 h 40-min. exercise uphill would be as osteogenic as the 40-min exercise downhill. Healthy postmenopausal women, 8 each, were assigned to a no-exercise condition (SED) or to 40- or 20-min exercise bouts, spaced 7 h apart, for walking uphill (40 Up and 20 Up) or downhill (40 Down and 20 Down) to produce differences in biomechanical variables. Exercise was initiated at 08:00 h one hour after eating in 40-min groups, and also 7 h later, two hours after the midday meal, in 20-min groups. Measurements were made of CICP (c-terminal peptide of type I collagen), osteocalcin (OC), and bone-specific alkaline phosphatase (BALP), markers of bone formation, and of the bone resorptive marker CTX (c-terminal telopeptide of type 1 collagen). The osteogenic ratios CICP/CTX, OC/CTX, and BALP/CTX were calculated. Only the 40-min downhill exercise of suprathreshold speed-enhanced momentum, increased the three osteogenic ratios, demonstrating the necessity of a 40-min, and inadequacy of a 20-min, exercise impulse. The failure of anabolic outcome in 40-min uphill exercise was attributed to a sustained elevation of PTH concentration, as its high morning elevation enhances the CTX circadian rhythm. We conclude that postmenopausal osteoporosis can be prevented or mitigated in sedentary women by 45 min of morning exercise of suprathreshold speed-enhanced increased momentum performed shortly after a meal while walking on level ground, or by 40-min downhill, but not 40-min uphill, exercise to avoid circadian PTH oversecretion. The principal stimulus for the anabolic effect is exercise, but the prerequisite for a pre-exercise meal demonstrates the requirement for nutrient facilitation.

Impact of metabolic syndrome and its components on bone remodeling in adolescents

Introduction Osteoporosis and metabolic syndrome (MetS) are diseases that have serious public health consequences, reducing the quality of life of patients and increasing morbidity and mortality, with substantial healthcare expenditures. Objective To evaluate the impact of MetS on bone mineral density (BMD) and biochemical markers of bone formation and resorption in adolescents with excess weight. Method A descriptive and analytical cross-sectional study was performed that evaluated 271 adolescents of both sexes (10 to 16 years). From the total sample, 42 adolescents with excess weight and the presence of MetS (14%) were selected. A further 42 adolescents with excess weight and without MetS were chosen, matched for chronological age, bone age, and pubertal developmental criteria to those with MetS, for each sex. Anthropometric measurements, blood pressure collection, and biochemical tests were performed in all adolescents, as well as evaluation of BMD and the bone biomarkers osteocalcin (OC), bone alkaline phosphatase (BAP), and carboxy-terminal telopeptide (S-CTx). Results The adolescents with excess weight and MetS exhibited significantly lower transformed BMD and concentrations of BAP, OC, and S-CTx compared to the matched group, except for OC in boys. A negative and significant correlation was observed between total body BMD and BAP (r = -0.55568; p = 0.005), OC (r = -0.81760; p = < .000), and S-CTx (r = -0.53838; p = 0.011) in girls. Conclusion Metabolic syndrome may be associated with reduced bone mineral density and biochemical markers of bone formation and resorption in adolescents with excess weight.

Different Sclerostin Response to Cycling and Running at the Same Exercise Intensity

Recreational cycling is a popular activity which stimulates and improves cardiovascular fitness. The corresponding benefits for bone are unclear. This study examined the effect of running (high-impact) vs. cycling (low-impact), at the same moderate-to-vigorous exercise intensity, on markers of bone formation (N-terminal propeptide of type I collagen, PINP) and bone resorption (C-telopeptide of type I collagen, CTX-1), a non-collagenous bone remodeling marker (osteocalcin), as well as bone-modulating factors, including parathyroid hormone (PTH), irisin (myokine) and sclerostin (osteokine). Thirteen healthy men (23.7±1.0 y) performed two progressive exercise tests to exhaustion (peak VO2) on a cycle ergometer (CE) and on a treadmill (TM). On subsequent separate days, in randomized order, participants performed 30-min continuous running or cycling at 70% heart rate reserve (HRR). Blood was drawn before, immediately post- and 1h into recovery. PTH transiently increased (CE, 51.7%; TM, 50.6%) immediately after exercise in both exercise modes. Sclerostin levels increased following running only (27.7%). Irisin increased following both running and cycling. In both exercise-modes, CTX-1 decreased immediately after exercise, with no significant change in PINP and osteocalcin. At the same moderate-to-vigorous exercise intensity, running appears to result in a greater transient sclerostin response compared with cycling, while the responses of bone markers, PTH and irisin are similar. The longer-term implications of this differential bone response need to be further examined.

Changes in bone metabolism associated with exposure to industrial vibration

The influence of general and local vibration on bone remodeling processes is investigated. The interrelations between the long - term exposure of industrial vibration and indicators of bone mineral density (T-and Z-criteria), biochemical markers of bone formation (osteocalcin, alkaline phosphatase) and bone resorption (ionized calcium, calcium/creatinine) were established.

Specific Effects of Anorexia Nervosa and Obesity on Bone Mineral Density and Bone Turnover in Young Women

Objective The threefold aim was to (1) compare areal bone mineral density (aBMD), bone turnover markers, and periostin levels in young women with either anorexia nervosa (AN) or obesity (OB) and controls (CON); (2) model the profiles according to age; and (3) determine the parameters associated with aBMD. Subjects and Methods One hundred and fifty-two young women with ages ranging from 16.0 to 27.0 years were subdivided into 3 groups (AN, OB, CON). The CON group was age-matched by ±6 months. aBMD, bone turnover markers, and periostin levels were evaluated. Results aBMD modeling showed that hip aBMD was higher in OB than in the other 2 groups from 19 years, and AN presented lower values than CON from 21 years. aBMD at the lumbar spine was higher in older OB and CON women, starting from 20 to 22 years, but in AN the difference with the other 2 groups increased with age. Periostin levels were lower in OB than in AN or CON, but no variation with age was observed. Compared with controls, OB and AN presented similarly lower markers of bone formation, although markers of bone resorption were lower in OB and higher in AN. A modeling approach showed that markers of bone formation and resorption were lower in older than in younger CON, whereas the values of these bone markers remained relatively constant in AN and OB. In all groups, lean body mass (LBM) was the parameter most positively correlated with aBMD. Conclusion This study demonstrated that weight extremes (AN or OB) influence aBMD, bone remodeling and periostin profiles. Moreover, factors related to aBMD were specific to each condition, but LBM was the parameter most consistently associated with aBMD.

Short-term stall housing of horses results in changes of markers of bone metabolism

In previous research, stall-housing growing horses resulted in decreased bone mineral content (BMC) of the third metacarpal (MCIII) compared to pasture-housing. To determine whether stall confinement negatively impacts bone, regardless of age, and whether the effects could be reversed upon return to pasture, 12 mature horses (5-15 years) and 12 yearlings were pair-matched by age and gender and randomly assigned to one of two treatment groups: pasture (PT) or stall (ST). Horses on PT remained there for the 84-d study, while horses on ST spent the first 28 d in stalls and the remaining 56 d on pasture. Radiographs and blood samples were taken on d 0 for baseline determinants. Radiographs and blood were taken every 7 d for radiographic photodensitometry estimates of BMC and analysis of osteocalcin (OC) and C-telopeptide (CTX-1)-markers of bone formation and degradation. There were no differences in BMC between treatments at the medial cortex of MCIII in mature horses. There were treatment (P=0.05) and day (P<0.01) differences in BMC at the lateral cortex of MCIII. In yearling horses, the BMC of the medial cortex of MCIII had a day difference with the lowest overall average at d 21 and highest at d 70 (P=0.04). There were day by treatment differences (P<0.05) for both OC and CTX-1 with the mature and yearling horses on ST having lower OC on d 14 than PT horses (P<0.05) indicative of reduced bone formation. In mature and yearling ST horses, CTX-1 was greater on d 14 and 28 compared to horses on PT (P≤0.05) suggesting greater bone resorption. Results from serum markers of bone formation and deformation confirm that stalling negatively impacts bone formation in horses regardless of age.

Honey Supplementation and Exercise: A Systematic Review

Honey is a natural substance formed primarily of carbohydrates (~80%) which also contains a number of other compounds purported to confer health benefits when consumed. Due to its carbohydrate composition (low glycaemic index, mostly fructose and glucose), honey may theoretically exert positive effects when consumed before, during or after exercise. This review therefore appraised research examining the effects of honey consumption in combination with exercise in humans. Online database (PubMed, MEDLINE, SPORTDiscus) searches were performed, yielding 273 results. Following duplicate removal and application of exclusion criteria, nine articles were reviewed. Large methodological differences existed in terms of exercise stimulus, population, and the nutritional interventions examined. All nine studies reported biochemical variables, with four examining the effects of honey on exercise performance, whilst five described perceptual responses. Acute supplementation around a single exercise session appeared to elicit similar performance, perceptual, and immunological responses compared with other carbohydrate sources, although some performance benefit has been observed relative to carbohydrate-free comparators. When consumed over a number of weeks, honey may dampen immunological perturbations arising from exercise and possibly improve markers of bone formation. More well-controlled research is required to better understand the role for honey in a food-first approach to exercise nutrition.

Effect of Adjuvant Chemotherapy is Responsible for Decreasing Segmental and Total BMD in BC Postmenopausal Women

Background: Women with breast cancer are at increased risk for the development of osteoporosis and skeletal fractures, as consequences of aromatase inhibition or chemotherapy-induced ovarian failure. We investigated the effect of adjuvant chemotherapy on biochemical markers of bone formation and resorption as well as on bone mineral density (BMD) of non-metastatic breast cancer (NMBC) postmenopausal Egyptian women. Methods: We followed 100 newly diagnosed women with T1-3 N0-2 M0 breast cancer, who had a mean age (±SD) of 55.06±8.78 year, before and after receiving 6-cycles of CAF chemotherapy treatment protocol. All participant women were subjected to blood biochemical analysis for determining serum levels of: erythrocyte sedimentation rate, calcium, alkaline phosphatase (ALP), bone specific alkaline phosphatase (S.ALP), Osteocalcin, carboxytelopeptide of collagen type I (CTx-I), 25-Hydroxyvitamin D, Parathyroid Hormone (PTH) and tumor marker CA15-3. Segmental and total BMD were also investigated using Dual X-ray Absorptiometry technique. Results: We found ALP, S.ALP, and CTx-I levels were significantly lower (p<0.001), while PTH levels to be significantly higher for all women after chemotherapy as compared to their initial state before chemotherapy. Both segmental and total BMD, and consequently T- and Z-Scores after chemotherapy were significantly (p<0.01) lower than their levels before chemotherapy. We developed prediction mathematical formulae for spine, pelvis and total BMD for all women before and after chemotherapy. Conclusions: Adjuvant chemotherapy is responsible for decreasing both biochemical markers of bone formation and resorption as well as for decreasing segmental and total BMD in NMBC postmenopausal Egyptian women. We believe the mathematical formulae developed on basis of the two individual variables Age and BMI can be useful for assisting the clinician to frequently monitor bone health status of breast cancer patients in similar conditions.