Effects of equivalent sea-level and altitude training on VO2max and running performance.

Twelve middle-distance runners, each having recently completed a competitive track season, were divided into two groups matched for maximal oxygen uptake (VO2max), 2-mile run time and age. Group 1 trained for 3 wk at Davis, PB = 760 mmHg, running 19.3 km/day at 75% of sea-level (SL) VO2max, while group 2 trained an equivalent distance at the same relative intensity at the US Air Force Academy (AFA), PB = 586 mmHg. The groups then exchanged sites and followed a training program of similar intensity to the group preceding it for an additional 3 wk. Periodic near exhaustive VO2max treadmill tests and 2-mile competitive time trials were completed. Initial 2-mile times at the AFA were 7.2% slower than SL control. Both groups demonstrated improved performance in the second trial at the AFA (chi = 2.0%), but mean postaltitude performance was unchanged from SL control. VO2max at the AFA was reduced initially 17.4% from SL control, but increased 2.6% after 20 days. However, postaltitude VO2max was 2.8% below SL control. It is concluded that there is no potentiating effect of hard endurance training at 2,300-m over equivalently severe SL training on SL VO2max or 2-mile performance time in already well conditioned middle-distance runners.     

Effects of different exercise modes on mineralization, structure, and biomechanical properties of growing bone.

Weight bearing during exercise plays an important role in improving the mechanical properties of bone. The effect on bone of non-weight-bearing exercise such as swimming remains controversial. To investigate the effects of exercise mode on growing bone, 29 male Wistar rats (7 wk old) were randomly assigned to a running exercise group (Run, n = 9), a swimming exercise group (Swim, n = 10), or a nonexercise control group (Con, n = 10). During an 8-wk training session (20-60 min/day, 5 days/wk), the Run rats were trained at progressively increasing running speeds (12-22 m/min), and weights attached to the tail of the Swim rats were progressively increased from 0 to 2% of their body weight. The bone mineral density of the proximal tibiae of the Run rats was significantly higher than in the Swim (P < 0.05). Femoral wet weights of the two exercise groups were significantly higher than in the control group (P < 0.05). Interestingly, the percent difference between the tissue wet weight and dry weight (water content ratio), which is related to bone mechanical properties, was significantly higher in the tibiae of the Swim rats and the femora of both exercise groups compared with controls (P < 0.05). Extrinsic as well as intrinsic biomechanical material properties were measured in a three-point bending test. Bone mechanical properties of the tibiae and femora of rats in the Swim and Run groups were significantly greater than those in the control group (P < 0.05). In summary, different modes of exercise may benefit bone mechanical properties in different ways. The specific effects of swimming exercise (non-weight-bearing exercise) on bone require further study.     

Variations in running activity and enzymatic adaptations in voluntary running rats

The running behavior and biochemical markers of oxidative and glycolytic activities associated with voluntary running activity were studied in male Sprague-Dawley rats after 6 wk of training in exercise wheel cages. Twenty-four-hour recordings of running activity were used to quantify the number of individual running bouts, their duration and running speed, and the distance run per day. We then established three categories of voluntary running activity based on the mean distance run per day during the last 3 wk of training: low-activity runners averaged 2-5 km/day, medium runners 6-9 km/day, and high runners greater than 11 km/day. Each group demonstrated an intermittent, nocturnal running pattern, at relatively high intensities, with a similar mean running speed for all groups (avg approximately 45 m/min). Differences in total distance run per day were the result of variations in both the number and duration of individual running bouts. Specifically, high runners (n = 7) had 206 +/- 30 individual running bouts per 24 h, each lasting 87 +/- 7 s; medium runners (n = 7) 221 +/- 22 running bouts, lasting 47 +/- 5 s; and low runners (n = 7) 113 +/- 7 bouts, each lasting 40 +/- 7 s. Voluntary running depressed the rate of body weight gain compared with sedentary control rats, despite an increased food and water intake for all runners. Furthermore, drinking activity was temporally associated with running periods.(ABSTRACT TRUNCATED AT 250 WORDS)     

Swim-trained rats have greater bone mass, density, strength, and dynamics.

Weight-bearing exercise is traditionally recommended for improving bone health in postmenopausal women. Effects of swim exercise were studied as an alternative to weight-bearing exercise in ovariectomized rats. Rats in a swim group (Sw, n = 8) swam for 12 wk, 5 days/wk for 60 min per session. A control group (Con, n = 9) engaged in no structured exercise. Femurs were analyzed for bone mineral density and for bone mineral content by dual energy X-ray absorptiometry, biomechanical properties by three-point bending (Instron), and bone structure and formation by histomorphometry. Food intake did not differ among groups. Final body weights were significantly lower in Sw compared with Con (P < 0.05). Swimmers had significantly greater femoral shaft bone mineral density and content (P < 0.05) compared with Con. Femurs of the Sw group had greater mechanical properties (P < 0.05) compared with Con. Histomorphometric data were significantly better in the Sw group compared with Con after the 12-wk intervention (P < 0.05). In conclusion, data from this study demonstrate some beneficial effects of swim exercise on bone structure, turnover, and strength.     

Influence of type of mechanical loading, menstrual status, and training season on bone density in young women athletes

Bone mineral density (BMD) variables were compared in 2 groups of women Division I collegiate athletes-gymnasts (GYM) and cross-country runners (CC)-during the preseason and during the competitive season. An osteogenic advantage may exist in women athletes involved in impact loading (gymnastics) over those women in active loading sports like long-distance running. The effects of menstrual status and the time of the training season on BMD also were examined. Dietary intake, menstrual status, BMD, and serum estradiol levels were measured during the preseason and during the competitive season in 26 women athletes (18-22 years of age). GYM had significantly higher BMD (p < 0.05) at all sites for both the pre- and posttests compared to CC. Neither group experienced a significant change (p > 0.05) in BMD between trials for any site; however, CC showed slight decreases at all BMD sites from baseline to the posttest. GYM had a higher prevalence of self-reported menstrual cycle disturbances than CC. No significant difference (p > 0.05) in BMD was found between the eumenorrheic and menstrual dysfunction groups (oligo/amenorrheic). In conclusion, the gymnasts had significantly higher (p < 0.05) BMD than the runners, suggesting BMD is influenced by the type of mechanical loading. Menstrual status did not significantly affect BMD in these women athletes. Cross-country runners were determined to be at greater risk than the gymnasts for low bone mass; thus, it is recommended that these athletes include more high-impact activities in their training regimen to optimize their bone health.     

High bone mass gained by exercise in growing male mice is increased by subsequent reduced exercise.

Exercise-induced bone gains are lost if exercise ceases. Therefore, continued exercise at a reduced frequency or intensity may be required to maintain these benefits. In this study, we evaluated whether 4 wk of reduced exercise after 4 wk of running exercise in growing male mice results in the maintenance of high bone mass. Five-week-old mice were divided into the following groups: 1) baseline control; 2) 4-wk control; 3) 4-wk exercise; 4) 8-wk control; 5) 4-wk exercise followed by 4-wk cessation of training; and 6) 4-wk exercise followed by reduced exercise at half the frequency. The regimen consisted of exercise 6 days/wk, and the reduced exercise regimen consisted of running 3 days/wk on a treadmill for 30 min/day, at 12 m/min on a 10 degrees uphill slope. Running exercise significantly increased bone mineral density of the femur, periosteal mineral apposition rate, bone formation rate, percent labeled perimeter at the midfemur, and osteogenic activity of bone marrow cells. However, these parameters declined to the age-matched sedentary control after cessation of training. In contrast, the reduced exercise group had significantly higher mineral apposition rate compared with those of the sedentary control and cessation of training groups. Furthermore, bone mineral density for the reduced exercise group was significantly higher than those for the other groups. These results suggest that the high bone formation gained through exercise can be maintained, and bone mass was further increased by subsequent exercise even if the exercise frequency is reduced.     

Treadmill running starting 3 months after orchidectomy restores femoral bone mass in rats

The present study was designed to provide data on the effects on femoral bone of endurance training starting only 3 months after orchidectomy in rats. A total of 70 Wistar male rats were used at 8 weeks of age. On day 0 of the experiment, 10 rats were killed by cervical dislocation to be used as first controls. Among the 60 other animals, half was surgically castrated (CX) or sham operated (SH). On day 90, 10 CX and 10 SH were killed and used as intermediary controls (ICX and ISH). Among the other 20 CX and 20 SH, 10 within each group (CXE, SHE) were selected for treadmill running (60% maximal oxygen uptake, 1 h x day(-1), 5 days x week(-1) for 12 weeks). The 20 other rats were used as sedentary controls (CXR, SHR) and killed (as runners) on day 180. On day 90 femoral bone density (BMD) and mineral content (BMC) were lower in ICX than in ISH. On day 180 total femoral BMD was lower in CXR than in CXE. Simultaneously metaphyseal femoral BMD was lower in CXR than in CXE, SHR or SHE. Furthermore, at that time, no significant difference concerning BMD and BMC was observed between SHR and CXE. This would indicate that treadmill running starting only 3 months after orchidectomy is able to restore BMD and BMC to control values, mainly by inhibiting bone resorption (as shown by decreased urinary deoxypyridinoline excretion in CXE) without decreasing osteoblastic activity (evaluated by plasma osteocalcin concentration).     

Action of green tea catechin on bone metabolic disorder in chronic cadmium-poisoned rats

The purpose of this study was to investigate the effects of green tea catechin on bone metabolic disorders and its mechanism in chronic cadmium-poisoned rats. Sprague-Dawley male rats weighing 100+/-10 g were randomly assigned to one control group and three cadmium-poisoned groups. The cadmium groups included a catechin free diet (Cd-0C) group, a 0.25% catechin diet (Cd-0.25C) group and a 0.5% catechin diet (Cd-0.5C) group according to their respective levels of catechin supplement. After 20 weeks, the deoxypyridinoline and crosslink values measured in urine were significantly increased in the Cd-0C group. Cadmium intoxication seemed to lead to an increase in bone resorption. In the catechin supplemented group (Cd-0.5C group), these urinary bone resorption marks, were decreased. The serum osteocalcin content in the cadmium-poisoned group was significantly increased as compared with the control group. In the catechin supplemented group serum osteocalcin content values were lower than the control group. The cadmium-intoxicated group (Cd-0C group), had lower bone mineral density than the control group (total body, vertebra, pelvis, tibia and femur). The catechin supplement increased bone mineral density to about the same as the control group. Bone mineral content showed a similar trend to total bone mineral density. Therefore, the bone mineral content of the Cd-0C group at the 20th week was significantly lower than the control group. The catechin supplemented group (Cd-0.5C group) was about the same as the control group. The cause of decreasing bone mineral density and bone mineral content by cadmium poisoning was due to the fast bone turnover rate, where bone resorption occurred at a higher rate than bone formation. The green tea catechin aided in normalizing bone metabolic disorders in bone mineral density, bone mineral content and bone calcium content caused by chronic cadmium intoxication.     

Differential effects of jump versus running exercise on trabecular architecture during remobilization after suspension-induced osteopenia in growing rats

High-impact exercise is considered to be very beneficial for bones. We investigated the ability of jump exercise to restore bone mass and structure after the deterioration induced by tail suspension in growing rats and made comparisons with treadmill running exercise. Five-week-old male Wistar rats (n = 28) were randomly assigned to four body weight-matched groups: a spontaneous recovery group after tail suspension (n = 7), a jump exercise group after tail suspension (n = 7), a treadmill running group after tail suspension (n = 7), and age-matched controls without tail suspension or exercise (n = 7). Treadmill running was performed at 25 m/min, 1 h/day, 5 days/wk. The jump exercise protocol consisted of 10 jumps/day, 5 days/wk, with a jump height of 40 cm. Bone mineral density (BMD) of the total right femur was measured by dual-energy X-ray absorptiometry. Three-dimensional trabecular bone architecture at the distal femoral metaphysis was evaluated using microcomputed tomography. After 5 wk of free remobilization, right femoral BMD, right hindlimb muscle weight, and body weight returned to age-matched control levels, but trabeculae remained thinner and less connected. Although both jump and running exercises during the remobilization period increased trabecular bone mass, jump exercise increased trabecular thickness, whereas running exercise increased trabecular number. These results indicate that restoration of trabecular bone architecture induced by jump exercise during remobilization is predominantly attributable to increased trabecular thickness, whereas running adds trabecular bone mass through increasing trabecular number, and suggest that jumping and running exercises have different mechanisms of action on structural characteristics of trabecular bone.     

Menstrual state and exercise as determinants of spinal trabecular bone density in female athletes.

OBJECTIVE--To study the effects of amenorrhoea and intensive back exercise on the bone mineral density of the lumbar spine in female athletes. DESIGN--Cross sectional study comparing amenorrhoeic with eumenorrhoeic athletes and rowers with non-rowers. SETTING--The British Olympic Medical Centre, Northwick Park Hospital. PATIENTS--46 Elite female athletes comprising 19 rowers, 18 runners, and nine dancers, of whom 25 were amenorrhoeic and 21 eumenorrhoeic. MAIN OUTCOME MEASURE--Trabecular bone mineral density of the lumbar spine measured by computed tomography. RESULTS--Mean trabecular bone mineral density was 42 mg/cm3 (95% confidence interval 22 to 62 mg/cm3) lower in the amenorrhoeic than the eumenorrhoeic athletes; this difference was highly significant (p = 0.0002). Mean trabecular bone mineral density was 21 mg/cm3 (1 to 41 mg/cm3) lower in the non-rowers than the rowers; this was also significant (p = 0.05). There was no interaction between these two effects (p = 0.28). CONCLUSION--The effect of intensive exercise on the lumbar spine partially compensates for the adverse effect of amenorrhoea on spinal trabecular bone density.     

Relation between body size and bone mineral density with special reference to sex hormones and calcium regulating hormones in elderly females.

We studied the relation between body size and bone mineral density in elderly females. The study included a total of 93 ambulatory females aged over 60 years. They were divided into 3 groups according to their body mass index (BMI; kg/m2): slender group with BMI less than 20 (n = 28), normal group with BMI of 20 to 24.9 (n = 43) and obese group with BMI greater than or equal to 25 (n = 22). Fracture incidence, bone mineral density, calcium regulating hormones and steroid hormones were studied in an intergroup comparative manner. The incidence of vertebral fracture was found to be negatively correlated with BMI (the incidences of vertebral fracture in slender, normal and obese were 78.6, 48.8 and 22.7%, respectively) and bone mineral density was also BMI-related (0.390 +/- 0.016, 0.456 +/- 0.015 and 0.493 +/- 0.018 g/cm2, respectively: p less than 0.01 in ANOVA; mean +/- SE). The number of years after menopause was shorter in patients with a higher BMI. There was no intergroup difference in serum levels of PTH, vitamin D and estrogens. On the other hand, serum levels of calcitonin, DHEA, DHEAS, delta-4 androstenedione and testosterone were found to be higher in subjects with a higher BMI. From the present results, it seems that bone mineral density is supported not only by weight-bearing stress upon bone, but also by serum levels of calcitonin and androgens in obese females.     

Effects of beta-hydroxy-beta-methylbutyrate on muscle damage after a prolonged run.

This study examined the effects of supplemental beta-hydroxy-beta-methylbutyrate (HMB) on muscle damage as a result of intense endurance exercise. Subjects (n = 13) were paired according to their 2-mile run times and past running experience. Each pair was randomly assigned a treatment of either HMB (3 g/day) or a placebo. After 6 wk of daily training and supplementation, all subjects participated in a prolonged run (20-km course). Creatine phosphokinase and lactate dehydrogenase (LDH) activities were measured before and after a prolonged run to assess muscle damage. The placebo-supplemented group exhibited a significantly greater (treatment main effect, P = 0.05) increase in creatine phosphokinase activity after a prolonged run than did the HMB-supplemented group. In addition, LDH activity was significantly lower (treatment main effect, P = 0.003) with HMB supplementation compared with the placebo-supplemented group. In conclusion, supplementation with 3.0 g of HMB results in a decreased creatine phosphokinase and LDH response after a prolonged run. These findings support the hypothesis that HMB supplementation helps prevent exercise-induced muscle damage.     

Relationships of Age and Weekly Running Distance to BMI and Circumferences in 41, 582 Physically Active Women

Objective: To assess in women whether age‐related increases in adiposity are dependent on exercise, and, contrariwise, whether exercise‐related declines in adiposity are dependent on age. Research Methods and Procedures: Cross‐sectional analyses were conducted of 41, 582 female runners. Results: Age affected the relationships between vigorous exercise and adiposity. The decline in BMI per kilometer per week run was linear in 18 to 23 year olds and became increasingly non‐linear (convex) with age. Waist, hip, and chest circumferences declined significantly with running distance across all age groups, but the declines were significantly greater in older than younger women, particularly among shorter distance runners. The relationships between body circumferences and running distance became increasingly convex in older women. Conversely, vigorous exercise diminished the apparent increase in adiposity with age. The increase in average BMI with age was greatest in women who ran <8 km/wk, intermediate in women who ran 8 to 15 km/wk or 16 to 31 km/wk, and least in those who averaged over 32 km/wk. Before age 45, waist circumference rose for those who ran 0 to 7 km/wk, showed no significant relationship to age for those who ran 8 to 39 km/wk, and declined in those who ran 40 to 55 and 56 km/wk and more. Age related‐increases in hip and chest circumferences before 45 years old were significantly less in women who ran longer weekly distances. Discussion: These cross‐sectional associations are consistent with the hypothesis that exercise may mitigate age‐related increases in adiposity and that age affects exercise‐induced reductions in adiposity (although causality remains to be determined experimentally).     

Papillary mechanics and cardiac morphology of infarcted rat hearts after training

Infarction of the left ventricle was induced by ligation of the coronary artery in male Sprague-Dawley rats under ketamine-xylazine anesthesia. Three weeks after surgery, animals were assigned to a trained (n = 21; running at 20 m/min, 10% grade, 1 h/day, 5 days/wk) or nontrained group (n = 23) for an additional 8 wk. A third, sham-operated control group (n = 16) remained cage sedentary for 11 wk. Ventricular mass was greater in the trained and nontrained infarct groups [1,335 +/- 57.3 and 1,414 +/- 56.1 mg, respectively (mean +/- SE)] compared with the control group (1,155 +/- 50.9 mg) (P less than or equal to 0.05). The diameter of septal fibers was 13% greater in the trained and 17% greater in the nontrained infarct groups compared with control. The specific peak developed force and maximum rate of force development of left ventricular papillary muscle in vitro were 75 and 62% greater in both infarcted groups compared with the control group; these variables were unaffected by training. Myofibrillar adenosine triphosphatase activity of septum was 20% lower in both infarct groups compared with sham-operated animals. We conclude that exercise training did not alter the magnitude of morphological and physiological adaptations to infarction.     

Immature tendon adaptation to strenuous exercise

White Leghorn roosters (3 wk old) were randomly assigned to runner or control groups. Runners were subjected to a progressive treadmill running program for 8 wk, 5 days/wk at 70-80% maximal O2 consumption (VO2 max). After 8 wk, runners showed a significant elevation in gastrocnemius fumarase activity (51%) and a 21% increase in VO2max compared with controls. The exercise program induced a significant increase in tendon collagen deposition (46%) without any changes in DNA, proteoglycan, and collagen concentrations or tendon dry weight. Also, tendon collagen from runners contained fewer (50%) pyridinoline cross-links. These results suggest that high-intensity exercise causes greater matrix-collagen turnover in growing chickens, resulting in reduced maturation of tendon collagen.     

Glucose uptake patterns in exercised skeletal muscles of elite male long-distance and short-distance runners

The aim of this study was to determine glucose uptake patterns in exercised skeletal muscles of elite male long-distance and short-distance runners. Positron emission tomography (PET) using 18F-fluoro-2-deoxyglucose (FDG) was performed to determine the patterns of glucose uptake in lower limbs of short-distance (SD group, n=8) and long-distance (LD group, n=8) male runners after a modified 20 min Bruce treadmill test. Magnetic resonance imaging (MRI) was used to delineate the muscle groups in lower limbs. Muscle groups from hip, knee, and ankle movers were measured. The total FDG uptake and the standard uptake value (SUV) for each muscle group were compared between the 2 groups. For the SD and LD runners, the 2 major muscle groups utilizing glucose during running were knee extensors and ankle plantarflexors, which accounted for 49.3 +/- 8.1% (25.1 +/- 4.7% and 24.2 +/- 6.0%) of overall lower extremity glucose uptake for SD group, and 51.3 +/- 8.0% (27.2 +/- 2.7% and 24.0 +/- 8.1%) for LD group. No difference in muscle glucose uptake was noted for other muscle groups. For SD runners, the SUVs for the muscle groups varied from 0.49 +/- 0.27 for the ankle plantarflexors, to 0.20 +/- 0.08 for the hip flexor. For the LD runners, the highest and lowest SUVs were 0.43 +/- 0.15 for the ankle dorsiflexors and 0.21 +/- 0.19 for the hip. For SD and LD groups, no difference in muscle SUV was noted for the muscle groups. However, the SUV ratio between the ankle dorsiflexors and plantarflexors in the LD group was significantly greater than that in the SD group. We thus conclude that the major propelling muscle groups account for approximately 50% of lower limb glucose utilization during running. Thus, the other muscle groups involving maintenance of balance, limb deceleration, and shock absorption utilize an equal amount. This result provides a new insight into glucose distribution in skeletal muscle, suggesting that propellers and supporters are both energetically important during running. Furthermore, for each unit muscle volume, movers of ankle are more glucose-demanding than those of hip.     

Glucocorticosteroid-induced osteoporosis in adult primiparous Göttingen miniature pigs: effects on bone mineral and mineral metabolism

Information on the pathophysiology of glucocorticoid-induced osteoporosis (GIO) is limited, since its clinical picture often reflects a combined effect of glucocorticoids (GC) and the treated systemic disease (i.e., inflammation and immobility). In 50 healthy adult (30-mo-old) primiparous G?ttingen minipigs, we studied the short-term (8 mo, n = 30) and long-term (15 mo, n = 10) effect of GC on bone and mineral metabolism longitudinally and cross-sectionally compared with a control group (n = 10). All animals on GC treatment received prednisolone orally at a dose of 1.0 mg x kg body wt(-1) x day(-1) for 8 wk and thereafter at 0.5 mg/kg body wt(-1) x day(-1). In the short term, GC reduced bone mineral density (BMD) at the lumbar spine by -47.5 +/- 5.1 mg/cm(3) from baseline (P < 0.001), which was greater (P < 0.05) than the loss [not significant (NS)] in the control group of -11.8 +/- 12.6 mg/cm(3). Calcium absorption decreased from baseline by -2,488 +/- 688 mg/7 days (P < 0.001) compared with -1,380 +/- 1,297 mg/7 days (NS) in the control group. Plasma bone alkaline phosphatase (BAP) decreased from baseline by -17.8 +/- 2.2 U/l (P < 0.000), which was significantly different (P < 0.05) from the value of the control group of -1.43 +/- 4.8 U/l. In the long term, the loss of BMD became more pronounced and bone mineral content (BMC), trabecular thickness, mechanical stability, calcium absorption, 25-hydroxyvitamin D(3), 1,25-dihydroxyvitamin D(3), and parathyroid hormone tended to be lower compared with the control group. There was a negative association between the cumulative dose of GC and BMD, which was associated with impaired osteoblastogenesis. In conclusion, the main outcomes after GC treatment are comparable to symptoms of GC-induced osteoporosis in human subjects. Thus the adult G?ttingen miniature pig appears to be a valuable animal model for GC-induced osteoporosis.     

Mitogenic response of T-lymphocytes to exercise training and stress

The impact of exercise training and stress on the immune response was examined by measuring the mitogenic response of spleen lymphocytes to the T-cell mitogen concanavalin A (Con-A). Male Sprague-Dawley rats were divided into four groups: sedentary controls (n = 11), handled controls (n = 12), treadmill runners (n = 10), and voluntary runners (n = 11) housed in running wheels. The treadmill group ran at 22 m/min (0.8 mph) for 45 min, 5 days/wk for 8 wk. After the training period, spleen lymphocytes isolated from each rat were incubated with Con-A for 54 h, pulsed with radiolabeled thymidine for 18 h, and counted for tritium activity. Counts per minute per group (means +/- SE) were as follows: sedentary, 6,839 +/- 1,461; handled, 8,959 +/- 1,576; voluntary runners, 13,126 +/- 2,069; and treadmill runners, 18,950 +/- 5,975. One-way analysis of variance and Tukey's highly significant difference test found the counts per minute of the treadmill runners to be significantly different from the counts per minute of the sedentary animals. These results indicate that the responsiveness of spleen lymphocytes to Con-A increases as the level of stress and exercise increases.     

Protein-containing nutrient supplementation following strength training enhances the effect on muscle mass, strength, and bone formation in postmenopausal women.

We evaluated the response of various muscle and bone adaptation parameters with 24 wk of strength training in healthy, early postmenopausal women when a nutrient supplement (protein, carbohydrate, calcium, and vitamin D) or a placebo supplement (a minimum of energy) was ingested immediately following each training session. At inclusion, each woman was randomly and double-blindedly assigned to a nutrient group or a placebo (control) group. Muscle hypertrophy was evaluated from biopsies, MRI, and dual-energy X-ray absorptiometry (DEXA) scans, and muscle strength was determined in a dynamometer. Bone mineral density (BMD) was measured using DEXA scans, and bone turnover was determined from serum osteocalcin and collagen type I cross-linked carboxyl terminal peptide. The nutrient group improved concentric and isokinetic (60 degrees /s) muscle strength from 6 to 24 wk by 9 +/- 3% (P < 0.01), whereas controls showed no change (1 +/- 2%, P > 0.05). Only the nutrient group improved lean body mass (P < 0.05) over the 24 wk. BMD responded similarly at the lumbar spine but changed differently in the two groups at the femoral neck (P < 0.05) [control: 0.943 +/- 0.028 to 0.930 +/- 0.024 g/mm(3) (-1.0 +/- 1.4%); nutrient group: 0.953 +/- 0.051 to 0.978 +/- 0.043 g/mm(3) (3.8 +/- 3.4%)] when adjusted for age, body mass index, and BMD at inclusion. Bone formation displayed an interaction (P < 0.05), mainly caused by increased osteocalcin at 24 wk in the nutrient group. In conclusion, we report that nutrient supplementation results in superior improvements in muscle mass, muscle strength, femoral neck BMD, and bone formation during 24 wk of strength training. The observed differences following such a short intervention emphasize the significance of postexercise nutrient supply on musculoskeletal maintenance.