Category Archives: Exercise

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

Calcium and Exercise in Rats

Abstract

Short- and long-term effects of calcium and exercise on bone mineral density in ovariectomized rats.

At the level of prevention of bone mineral loss produced by ovariectomy, the aim of the present study was to determine the effect produced by supplementation of Ca in the diet and a moderate exercise programme (treadmill), simultaneously or separately, in ovariectomized rats, an experimental model of postmenopausal bone loss. Female Wistar rats (n 110, 15 weeks old) were divided into five groups: (1) OVX, rats ovariectomized at 15 weeks of age, fed a standard diet; (2) SHAM, rats sham operated at 15 weeks of age, fed a standard diet; (3) OVX-EX, ovariectomized rats, fed a standard diet and performing the established exercise programme; (4) OVX-Ca, ovariectomized rats fed a diet supplemented with Ca; (5) OVX-EXCa, ovariectomized rats with the exercise programme and diet supplemented with Ca. The different treatments were initiated 1 week after ovariectomy and were continued for 13 weeks for subgroup 1 and 28 weeks for subgroup 2, to look at the interaction of age and time passed from ovariectomy on the treatments. Bone mineral density (BMD) was determined, at the end of the study, in the lumbar spine (L2, L3 and L4) and in the left femur using a densitometer. Bone turnover was also estimated at the end of the study, measuring the serum formation marker total alkaline phosphatase (AP) and the resorption marker serum tartrate-resistant acid phosphatase (TRAP). As expected, OVX rats showed a significant decrease (P<0.05) in BMD, more pronounced in subgroup 2, and a significant increase in AP and TRAP with regard to their respective SHAM group. The simultaneous treatment with Ca and exercise produced the best effects on lumbar and femoral BMD of ovariectomized rats, partially avoiding bone loss produced by ovariectomy, although it was not able to fully maintain BMD levels of intact animals. This combined treatment produced a significant increase in AP, both in subgroups 1 and 2, and a decrease in TRAP in subgroup 1, with regard to OVX group. The exercise treatment alone was able to produce an increase in BMD with regard to OVX group only in subgroup 1 of rats (younger animals and less time from ovariectomy), but not in subgroup 2. In agreement with this, there was an increase of AP in both subgroups, lower than that observed in animals submitted to exercise plus Ca supplement, and a decrease of TRAP in subgroup 1, without significant changes in this marker in the older rats. Ca treatment did not produce any significant effect on BMD in OVX rats in both subgroups of animals, showing a decrease of AP and TRAP levels in the younger animals with no significant variations in markers of bone remodelling in the older female rats compared with their respective OVX group.

Gala J, Díaz-Curiel M, de la Piedra C, Calero J
Br. J. Nutr. Oct 2001
PMID: 11591240

I don’t know what to make of this.

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?

GH + Exercise No Benefit Over Exercise Alone

Abstract

Effect of resistance exercise and growth hormone on bone density in older men.

The purpose of this study was to evaluate whether 16 weeks of heavy resistance exercise training combined with daily growth hormone administration (GH) increases bone mineral density in 64-75-year-old men greater than resistance exercise training without GH supplementation.
Eighteen healthy, elderly men (67 +/- 1 year) followed a 16-week progressive resistance training programme (75-90% maximum strength, 5-10 repetitions/set, 4 sets/day, 4 days/week) after double-blind, random assignment to either a GH (12.5 or 18 micrograms/kg/day, equivalent to 25 or 36 mU/kg/day, n = 7) or placebo (n = 11) group.
Before and at the end of 16 weeks of resistance exercise with or without GH administration, body composition, whole body and regional bone mineral density (BMD) were determined by dual-energy X-ray absorptiometry. Serum osteocalcin and IGF-I were determined by radioimmunoassay before, during and at the end of treatment.
Increments in fat-free mass and training-specific maximum voluntary muscle strength were similar in both groups after training. Serum insulin-like growth factor-I (IGF-I) and osteocalcin levels were increased (P < 0.05) after exercise training plus GH. In comparison to initial measures, bone mineral density (g/cm2) of the proximal femur (Ward’s triangle) was increased (P < 0.05) after 16 weeks of exercise training plus placebo treatment. Sixteen weeks of exercise training plus GH treatment did not increase whole body, spine or hip (femoral neck, trochanter, Ward’s triangle) bone mineral density more than exercise plus placebo treatment.
These findings suggest that in these older men with normal bone mineral density, short-term resistance exercise training increased regional bone mineral density, but the addition of daily GH administration did not enhance whole body or regional bone mineral density despite GH-induced increments in serum IGF-I and osteocalcin. This implies that GH administration during a 16-week resistance exercise training programme may increase bone turnover without increasing bone mineral accumulation.

Yarasheski KE, Campbell JA, Kohrt WM
Clin. Endocrinol. (Oxf) Aug 1997
PMID: 9302398