Tag Archives: human

Review: Exercise and Bone Markers

Abstract

Bone metabolism markers in sports medicine.

Bone mass can be viewed as the net product of two counteracting metabolic processes, bone formation and bone resorption, which allow the skeleton to carry out its principal functions: mechanical support of the body, calcium dynamic deposition and haemopoiesis. Besides radiological methods, several blood and urinary molecules have been identified as markers of bone metabolic activity for estimating the rates and direction of the biological activities governing bone turnover. The advantages for the use of bone metabolism markers are that they are potentially less dangerous than radiological determinations, are more sensitive to changes in bone metabolism than radiological methods and are easily collected and analysed. The disadvantages are that they have high biological variability. Physical exercise is a known source of bone turnover and is recommended for preventing osteoporosis and bone metabolism problems. There are numerous experiments on bone metabolism markers after acute exercise, but not after long-term training and during or after a whole competition season. Moreover, few studies on bone metabolism markers have evaluated their performance in elite and top-level athletes, who have a higher bone turnover than sedentary individuals. Despite discrepant results among studies, most have shown that short exercise is insufficient for modifying serum concentrations of bone metabolism markers. Marker variations are more evident after several hours or days after exercise, bone formation markers are more sensitive than bone resorption markers, and stimulation of osteoblast and/or osteoclast functions is exercise dependent but the response is not immediate. The response depends on the type of exercise; the markers seem to be less sensitive to resistance exercise and the intensity of exercise is not discriminate. Comparisons between trained subjects and untrained controls have demonstrated the influence of exercise on bone turnover. During training, carboxy-terminal collagen cross-links (CTx), a bone resorption marker, was shown to be less sensitive than amino-terminal cross-linking telopeptide of type I collagen (NTx) and urinary pyridinolines, which were sensitive to anaerobic exercise. Whereas, the bone formation markers, bone alkaline phosphatase (BAP) and osteocalcin (OC) changed after 1 month and 2 months of an exercise programme, respectively. After 2 months, while BAP normalized, it was found to be sensitive to aerobic exercise and OC was found to be sensitive to anaerobic exercise. After prolonged training and competition, bone formation markers are found to change in sedentary subjects enrolled in a physical activity programme. Professional athletes show changes in bone formation markers depending on programme intensity, whereas bone resorption appears to stabilize. Crucial for long-term training, are the characteristics of exercise (e.g. weight-bearing, impact).

Banfi G, Lombardi G, Colombini A, Lippi G
Sports Med Aug 2010
PMID: 20632739

Aerobic and Resistance Exercise May Increase Bone Formation in Young Women

Abstract

Influence of exercise mode and osteogenic index on bone biomarker responses during short-term physical training.

Prescribing exercise based on intensity, frequency, and duration of loading may maximize osteogenic responses in bone, but a model of the osteogenic potential of exercise has not been established in humans. In rodents, an osteogenic index (OI) has been used to predict the osteogenic potential of exercise. The current study sought to determine whether aerobic, resistance, or combined aerobic and resistance exercise programs conducted over eight weeks and compared to a control group could produce changes in biochemical markers of bone turnover indicative of bone formation. We further sought to determine whether an OI could be calculated for each of these programs that would reflect observed biochemical changes. We collected serum biomarkers [bone-specific alkaline phosphatase (BAP), osteocalcin, tartrate-resistant acid phosphatase (TRAP), C-terminal telopeptide fragment of type I collagen (CTx), deoxypyridinoline (DPD), 25-hydroxy vitamin D (25(OH)D), and parathyroid hormone (PTH)] in 56 women (20.3+/-1.8 years) before, during and after eight weeks of training. We also measured bone mineral density (BMD) at regional areas of interest using DXA and pQCT. Biomarkers of bone formation (BAP and osteocalcin) increased in the Resistance and Combined groups (p<0.05), while biomarkers of bone resorption (TRAP and DPD) decreased and increased, respectively, after training (p<0.05) in all groups. Small changes in volumetric and areal BMD (p<0.05) were observed in the distal tibia in the Aerobic and Combined groups, respectively. Mean weekly OIs were 16.0+/-1.9, 20.6+/-2.2, and 36.9+/-5.2 for the Resistance, Aerobic, and Combined groups, respectively. The calculated osteogenic potential of our programs did not correlate with the observed changes in biomarkers of bone turnover. The results of the present study demonstrate that participation in an eight week physical training program that incorporates a resistance component by previously inactive young women results in alterations in biomarkers of bone remodeling indicative of increased formation without substantial alterations in markers of resorption.

Lester ME, Urso ML, Evans RK, Pierce JR…
Bone Oct 2009
PMID: 19520194

45 Minutes of Resistance Exercise Reduces Resorption for 8 Hours

Abstract

Acute effects of moderate intensity resistance exercise on bone cell activity.

Resistance exercise has positive effects on bone mass, but little is known about the mechanisms by which this occurs. The purpose of this study was to determine if a single bout of moderate intensity resistance exercise alters biochemical markers of bone cell activity. Indices of bone turnover were measured in nine healthy, untrained men (21.9 +/- 1.2 yrs old), before and following a single 45 minute session of resistance exercise, and during a control trial. A cross-over design was used so that all participants performed both trials in random order. Blood samples were collected immediately before, immediately after, and at 1, 8, 24, and 48 hours post exercise and analyzed for bone-specific alkaline phosphatase (BAP), type I collagen propeptide (PICP), and type I collagen N-telopeptide (sNTX). Urine from the second morning void was collected over four days (day before, day of, and two days following exercise) and analyzed for type I collagen N-telopeptide (uNTX). Exercise resulted in a significant increase (p < 0.05) in the ratio of biochemical markers of bone formation to bone resorption eight hours post exercise, largely due to a decrease in sNTX. Markers return to baseline within 24 hrs. These data suggest that moderate intensity resistance training acutely reduces bone resorption, leading to a favorable change in overall bone turnover, for at least 8 hours post exercise in untrained young men. Further work is needed to determine if long-term benefits to bone strength follow with persistent training.

Whipple TJ, Le BH, Demers LM, Chinchilli VM…
Int J Sports Med Oct 2004
PMID: 15459829

Resistance Exercise Counters Bed Rest

Abstract

Resistance exercise as a countermeasure to disuse-induced bone loss.

During spaceflight, skeletal unloading results in loss of bone mineral density (BMD). This occurs primarily in the spine and lower body regions. This loss of skeletal mass could prove hazardous to astronauts on flights of long duration. In this study, intense resistance exercise was used to test whether a training regimen would prevent the loss of BMD that accompanies disuse. Nine subjects (5 men, 4 women) participated in a supine maximal resistance exercise training program during 17 wk of horizontal bed rest. These subjects were compared with 18 control subjects (13 men, 5 women) who followed the same bed rest protocol without exercise. Determination of treatment effect was based on measures of BMD, bone metabolism markers, and calcium balance obtained before, during, and after bed rest. Exercisers and controls had significantly (P < 0.05) different means, represented by the respective following percent changes:

lumbar spine BMD, +3% vs. -1%;
total hip BMD, +1% vs. -3%;
calcaneus BMD, +1% vs. -9%;
pelvis BMD, -0.5% vs. -3%;
total body BMD, 0% vs. -1%;
bone-specific alkaline phosphatase, +64% vs. 0%;
alkaline phosphatase, +31% vs. +5%;
osteocalcin, +43% vs. +10%;
1,25 dihydroxyvitamin D, +12% vs. -15%;
parathyroid hormone intact molecule, +18% vs. -25%; and
serum and ionized calcium, -1% vs. +1%.

The difference in net calcium balance was also significant (+21 mg/day vs. -199 mg/day, exercise vs. control). The gastrocnemius and soleus muscle volumes decreased significantly in the exercise group, but the loss was significantly less than observed in the control group. The results indicate that resistance exercise had a positive treatment effect and thus might be useful as a countermeasure to prevent the deleterious skeletal changes associated with long-duration spaceflight.

Shackelford LC, LeBlanc AD, Driscoll TB, Evans HJ…
J. Appl. Physiol. Jul 2004
PMID: 15220316 | Free Full Text

Biking Lowers Bone Density in Men; Cyclists 7x More Likely to Have Osteopenia

Abstract

Participation in road cycling vs running is associated with lower bone mineral density in men.

The effects of regular non-weight-bearing (NWB) exercise on bone health are largely unknown. The objective of the study was to determine the effects of participation in NWB sports on bone health in adult male recreational athletes. Male cyclists (NWB; n = 27) and runners (weight-bearing [WB]; n = 16) aged 20 to 59 years were recruited from the community. Whole-body and regional bone mineral content and bone mineral density (BMD), and body composition were assessed using dual x-ray absorptiometry. Bone formation and resorption markers, and hormones were measured in serum. Bone-loading history was estimated from a sports participation history questionnaire. Nutrient intake and current physical activity were estimated from 7-day written logs. The NWB athletes had significantly lower BMD of the whole body and spine than the WB athletes, despite having similar age, weight, body mass index, body composition, hormonal status, current activity level, and nutrient intakes. Sixty-three percent of NWB athletes had osteopenia of the spine or hip, compared with 19% of WB athletes. Cyclists were 7 times more likely to have osteopenia of the spine than runners, controlling for age, body weight, and bone-loading history. There were no group differences in serum markers of bone turnover. Based on the results of this study, current bone loading is an important determinant of whole-body and lumbar spine BMD. Therefore, bone-loading activity should be sustained during adulthood to maintain bone mass.

Rector RS, Rogers R, Ruebel M, Hinton PS
Metab. Clin. Exp. Feb 2008
PMID: 18191053

No Bone Benefit in Young Healthy Women from 3 Months Resistance Training or Protein

Abstract

Effects of resistance training and protein supplementation on bone turnover in young adult women.

The strength of aging bone depends on the balance between the resorption and formation phases of the remodeling process. The purpose of this study was to examine the interaction of two factors with the potential to exert opposing influences on bone turnover, resistance exercise training and high dietary protein intake. It was hypothesized that resistance training by young, healthy, untrained women with protein intakes near recommended levels (0.8 g.kg(-1).d(-1)) would promote bone formation and/or inhibit bone resorption, and that subsequent supplementation to provide 2.4 g protein.kg(-1).d(-1) would reverse these effects.
Bone formation was assessed with serum bone-specific alkaline phosphatase (BAP) and osteocalcin (OC), and bone resorption with urinary calcium and deoxypyridinoline (DPD). Biochemical, strength, anthropometric, dietary, and physical activity data were obtained from 24 healthy, untrained, eumenorrheic women (18-29 y) at baseline, after eight weeks of resistance training (3 d.wk(-1), approximately 1 hr.d(-1); 3 sets, 6-10 repetitions, 13 exercises, 75-85% maximum voluntary contraction), and after 12 weeks of resistance training and 10 days of protein/placebo supplementation. Subjects were randomized (double-blind) to either a high protein (HP) or training control (TC) group and, during the final 10 days, consumed either enough purified whey protein to bring daily protein intake to 2.4 g.kg(-1).d(-1), or an equivalent dose of isoenergetic, carbohydrate placebo.
Strength, lean tissue mass, and DPD increased significantly in both groups over time, while percent body fat and BAP decreased (repeated measures ANOVA, p < or = 0.05, Bonferroni correction). No significant changes were observed for serum OC or urinary calcium, and no significant group (TC, HP) x time (baseline, week 8, week 12) interactions emerged for any of the biochemical measures.
(1) Twelve weeks of high-intensity resistance training did not appear to enhance bone formation or inhibit bone resorption in young adult women, as assessed by biochemical markers of bone metabolism. (2) Subsequent maintenance of a high protein intake for 10 days in these regularly-training, calcium-replete women also showed no effects on bone metabolism.

Mullins NM, Sinning WE
Nutr Metab (Lond) Aug 2005
PMID: 16098231 | Free Full Text

The results are surprising. The full study is available using the link above. The authors note that these women were taking calcium supplements.

…to exclude the potential effects of calcium deficiency, each subject was given a supply of calcium supplements … to begin consuming for the duration of the study. Each was instructed to carry the calcium tablets in her purse or backpack, and was regularly reminded to consume one 500-mg tablet, twice per day.

There may not have been much more bone enhancement to gain.

…the subjects were healthy, eumenorrheic, calcium-replete women, regularly participating in high-intensity exercise.

They measured alkaline phosphatase, serum osteocalcin, urinary calcium. and urinary deoxypyridinoline.

It is possible that other biomarkers may have produced different results, and that, given a longer time frame, bone densitometry could detect osteogenic effects.

 

Insignificant Bone Density Increase After 9 Months of Strength Training

Abstract

Effect of resistance exercise on bone mineral density in premenopausal women.

To assess the effect of 9 months of strength training on total body and regional bone mineral density (BMD, g/cm(2)) in 58 premenopausal women aged 30-50 years.
Participants were randomized to either twice weekly supervised strength training for 15 weeks followed by 24 weeks of unsupervised training (treatment group) or control group. Height, weight, maximal muscular strength, nutrient intake and physical activity were assessed. Total body dual energy X-ray absorptiometry (DXA, Lunar Prodigy) scans were taken and analyzed for body composition (lean and fat mass), and BMD for total body and its sub-regions (spine, hip, arms and legs). All measurements were performed at baseline, 15 and 39 weeks. Analysis of covariance was used to assess group differences in BMD change adjusted for baseline BMD, weight, energy and calcium intake.
At baseline, the two groups had similar BMD and body size characteristics ( P<0.05 for all), except that the treatment group had lower body weight (-7.1 kg), and higher energy (+259 kJ/d) and calcium (+232 mg/d) intake at baseline. Adjusted % change in BMD over 15 weeks (0.5% vs. 0.4%) or 39 weeks (0.9% vs. 1.2%) did not differ significantly between the exercise and control groups, respectively. The exercise group increased BMD at the spine and legs (1-2.2%), while there was no change in the controls, but differences between groups were not significant.
Strength training over 9 months did not lead to significantly greater change in total body or regional BMD in premenopausal women.

Singh JA, Schmitz KH, Petit MA
Joint Bone Spine May 2009
PMID: 19217817

Weight Belt, Step-Ups, Chair Rises, Elastic Band, and Dumbbells + HRT

Abstract

Home-based resistance training improves femoral bone mineral density in women on hormone therapy.

This study tested whether moderate resistance training would improve femoral bone mineral density (BMD) in long-term users of hormone therapy with low BMD. The study was a 2-year randomized, controlled, trial (RCT) of moderate resistance training of either the lower extremity or the upper extremity. Eighty-five women participated in a 6-month observation period. The setting was center-based and home-based training. The participants were 189 women aged 59-78 years, with total femur T-scores from -0.8 to -2.8 and on hormone therapy (HT) for a minimum of 2 years (mean 11.8 years); 153 completed the trial. Lower extremity training used weight belts (mean 7.8 kg) in step-ups and chair rises; upper extremity training used elastic bands and dumbbells. Measurements were BMD and body composition [dual-energy X-ray absorptiometry (DXA)], bone turnover markers. Total femoral BMD showed a downward trend during the observation period: 0.35%+/-0.18% (P=0.14). The response to training was similar in the upper and lower groups in the primary outcomes. At 2 years, total femoral BMD increased 1.5% (95% CI 0.8%-2.2%) in the lower group and 1.8% (95% CI 1.1%-2.5%) in the upper group. Trochanter BMD increased 2.4% (95% CI 1.3%-3.5%) in the lower group and 2.5% (95% CI 1.4%-3.6%) in the upper group (for both analyses time effect P<0.001). At 1 year, a bone resorption marker (C-telopeptide) decreased 9% (P=0.04). Bone formation markers, bone-specific alkaline phosphatase, decreased 5% (P<0.001), and N-terminal type I procollagen peptide decreased 7% (P=0.01). Body composition (percent lean and percent body fat) was maintained in both groups. We concluded that long-term moderate resistance training reversed bone loss, decreased bone turnover, increased femur BMD, and maintained body composition. The similarity of response in upper and lower groups supports a systemic response rather than a site-specific response to moderate resistance training.

Judge JO, Kleppinger A, Kenny A, Smith JA…
Osteoporos Int Sep 2005
PMID: 15754082

Weight Belt Walking Maintains Bone

Abstract

An aerobic weight-loaded pilot exercise intervention for breast cancer survivors: bone remodeling and body composition outcomes.

Weight gain and bone loss are commonly reported in breast cancer survivors. The purpose of this pilot study is to assess feasibility and explore the effect of an aerobic weight-loaded exercise intervention on bone remodeling, weight, and body composition.
A one-group pre-posttest design was used to test a 16-24-week supervised walking exercise intervention among women within 2 years of menopause. Through Weeks 1-4, time and weight were progressively increased. By Week 5 and through the end of the intervention, a waist belt was loaded with 5 lb and participants spent 45 min on the treadmill 3 times/week. Bone remodeling was measured by serum biomarkers (N-terminal propeptides of type I collagen [NTX] and serum osteocalcin). Dual-energy absorptiometry scans assessed body composition. Data were collected at baseline and 16 and 24 weeks.
The majority of the 26 participants were married, well educated, and employed, with a mean age of 51.3 years (SD = 6.2). The high adherence (M = 88.2%, SD = 6.8) demonstrated feasibility. There were no significant changes in serum osteocalcin (p = .67), serum NTX (p = .31), lean muscle mass (p = .08), or percent fat mass for the group as a whole (p = .14), but fat mass increased for women on adjuvant endocrine therapy (p = .04). The women maintained their weight.
This novel exercise intervention for breast cancer survivors was feasible, and women otherwise at high risk for weight gain and bone loss maintained their weight and bone mass.

Knobf MT, Insogna K, DiPietro L, Fennie C…
Biol Res Nurs Jul 2008
PMID: 18705153

HRT + Exercise No Benefit Over HRT Alone

Abstract

Effects of exercise training on bone remodeling, insulin-like growth factors, and bone mineral density in postmenopausal women with and without hormone replacement therapy.

The purpose of this study was to determine the effects of 12 months of weight bearing and resistance exercise on bone mineral density (BMD) and bone remodeling (bone formation and bone resorption) in 2 groups of postmenopausal women either with or without hormone replacement therapy (HRT). Secondary aims were to characterize the changes in insulin-like growth factors-1 and -2 (IGF-1 and -2) and IGF binding protein 3 (IGFBP3) in response to exercise training. Women who were 3-10 years postmenopausal (aged 40-65 years) were included in the study. Women in the HRT and no HRT groups were randomized into the exercise intervention, resulting in four groups: (1) women not taking HRT, not exercising; (2) those taking HRT, not exercising; (3) those exercising, not taking HRT; and (4) women exercising, taking HRT. The number of subjects per group after 1 year was 27, 21, 25, and 17, respectively. HRT increased BMD at most sites whereas the combination of exercise and HRT produced increases in BMD greater than either treatment alone. Exercise training alone resulted in modest site-specific increases in BMD. Bone remodeling was suppressed in the groups taking HRT regardless of exercise status. The bone remodeling response to exercise training in women not taking HRT was not significantly different from those not exercising. However, the direction of change suggests an elevation in bone remodeling in response to exercise training, a phenomenon usually associated with bone loss. No training-induced differences in IGF-1, IGF-2, IGF-l:IGF-2 (IGF-1 : IGF-2), and IGFBP3 were detected.

Milliken LA, Going SB, Houtkooper LB, Flint-Wagner HG…
Calcif. Tissue Int. Apr 2003
PMID: 12574871

What kind of exercise where they doing?