Circulating MiR-21 expression is upregulated after 30 days of head-down tilt bed rest.

Relative expression of miR-21-5p in serum was upregulated in response to 30 days of bed rest, and miRNA fold changes were positively associated with serum calcium changes. INTRODUCTION: Circulating miRNAs (c-miRNAs) have potential as biomarkers of cellular activity, and they may play a role in cell-to-cell communication. The purpose of this study was to examine c-miRNA and bone marker responses to a 30-day six-degree head-down bed rest protocol at an ambient 0.5% CO2. METHODS: Eleven participants (6 males/5 females, 25-50 years) had fasting blood draws taken 3 days before and immediately after completing the 30-day bed rest protocol at the Institute for Aerospace Medicine in Germany. Serum relative expression of miRNAs associated with bone function (miR-21-5p, -100-5p, -125b-5p, -126-3p) were analyzed using qPCR, and serum bone markers were quantitated using ELISA. RESULTS: Serum bone markers, sclerostin, and calcium significantly increased (p ≤ 0.036), and total hip aBMD significantly decreased (p = 0.003) post bed rest. Serum miR-21-5p relative expression was significantly upregulated (p = 0.018) post bed rest. Fold changes in miR-126-3p (r = 0.82, p = 0.002) and miR-21-5p (r = 0.62, p = 0.042) were positively correlated with absolute change in serum calcium. There were no sex differences in miRNA responses; women had greater percent increases in TRAP5b (37.3% vs. 16.9% p = 0.021) and greater percent decreases in total hip aBMD (- 2.15% vs. - 0.69%, p = 0.034) than men. CONCLUSION: c-miR-21-5p has potential as a biomarker of bone resorption and bone loss in an unloading condition. The upregulation of miR-21-5p may reflect an increase in osteoclast activity after bed rest, which is corroborated by the increase in TRAP5b.

Fat Mass Is Negatively Associated with Muscle Strength and Jump Test Performance.

BACKGROUND: It is known that maintenance of muscle mass cannot prevent loss of muscle strength in older adults. Recent evidence suggests that fat mass can weaken the relationship between muscle mass and functional performance. No information exists if fat mass can independently affect muscle strength and jump test performance in middle-aged and older adults. OBJECTIVE: To assess the independent relationships between fat mass, leg muscle mass, lower extremity muscle strength, and jump test performance in adults, 55-75 years of age. DESIGN: Cross-sectional. SETTING: University laboratory. PARTICIPANTS: Fifty-nine older adults (men, n = 27, age = 64.8 ± 6.5 years; women, n = 32, age = 62.5 ± 5.1 years) participated in this study. MEASUREMENTS: Dual energy X-ray absorptiometry was used to measure fat mass and leg muscle mass. An average of 3 maximal countermovement jumps was used to calculate jump power and jump height. Two leg press and hip abduction strength were assessed by 1-repetition maximum testing. RESULTS: Stepwise sequential regression analysis of fat mass and leg muscle mass versus jump test performance and measures of muscle strength after adjusting for age, height, and physical activity revealed that fat mass was negatively associated with jump height (p = 0.047, rpartial = -0.410) in men. In women, fat mass was negatively associated with jump height (p = 0.003, rpartial = -0.538), leg press (p = 0.002, rpartial = -0.544), and hip abduction strength (p < 0.001, rpartial = -0.661). Leg muscle mass was positively associated with jump power in women (p = 0.047, rpartial = 0.372) only. CONCLUSIONS: Fat mass has an independent negative relationship with jump test performance in middle-aged and older men and women. This has clinical implications for rehabilitating neuromuscular performance in middle-aged and older adults.

Relationship between muscle performance and DXA-derived bone parameters in community-dwelling older adults.

OBJECTIVES: To examine association between muscle strength, jump test performance, muscle mass, bone mineral density (BMD), and bone strength in older adults. METHODS: Sixty individuals (55-75 years) participated. Leg press strength and bilateral hip abduction strength were evaluated by one repetition-maximum testing. Jump power (JPow) and jump height (JHt) were assessed by jump test performance. Relative skeletal muscle mass index (RSMI), total hip BMD, femoral neck BMD, lumbar spine BMD, section modulus (Z), cross-sectional moment of inertia (CSMI), and bone strength index (BSI) were determined by DXA. RESULTS: After adjusting for age and gender, leg press strength 1) positively correlated with the total hip BMD, femoral neck BMD, and Z (all P⟨0.05). Also, leg press strength predicted the total hip BMD (P=0.013) and femoral neck BMD (P=0.021), after adjusting for age, gender, and RSMI. No associations were found between jump test performance and bone density or strength. CONCLUSION: Leg press strength is positively associated with bone density and bone strength in older population. It might serve as an additional tool to identify at-risk individuals for osteoporosis.

Acute bone changes after lower limb amputation resulting from traumatic injury.

Bone health is critical for lower limb amputees, affecting their ability to use a prosthesis and their risk of osteoporosis. We found large losses in hip bone mineral density (BMD) and in amputated bone strength in the first year of prosthesis use, suggesting a need for load bearing interventions early post-amputation. INTRODUCTION: Large deficits in hip areal BMD (aBMD) and residual limb volumetric BMD (vBMD) occur after lower limb amputation; however, the time course of these bone quality changes is unknown. The purpose of this study was to quantify changes in the amputated bone that occur during the early stages post-amputation. METHODS: Eight traumatic unilateral amputees (23-53 years) were enrolled prior to surgery. Changes in total body, hip, and spine aBMD (dual-energy X-ray absorptiometry); in vBMD, stress-strain index (SSI), and muscle cross-sectional area (MCSA) (peripheral QCT); and in bone turnover markers were assessed after amputation prior to prosthesis fitting (pre-ambulatory) and at 6 and 12 months walking with prosthesis. RESULTS: Hip aBMD of the amputated limb decreased 11-15%, which persisted through 12 months. The amputated bone had decreases (p < 0.01) in BMC (-26%), vBMD (-21%), and SSI (-25%) from pre-ambulatory to 6 months on a prosthesis, which was maintained between 6 and 12 months. There was a decrease (p < 0.05) in the proportion of bone >650 mg/cm3 (58 to 43% of total area) or >480 mg/cm3 (65% to 53%), suggesting an increase in cortical porosity after amputation. Bone alkaline phosphatase and sclerostin were elevated (p < 0.05) at pre-ambulatory and then decreased towards baseline. Bone resorption markers were highest at surgery and pre-ambulatory and then progressively decreased (p < 0.05). CONCLUSIONS: Rapid and substantial losses in bone content and strength occur early after amputation and are not regained by 12 months of becoming ambulatory. Early post-amputation may be the most critical window for preventing bone loss.

Effects of whole-body vibration on acute bone turnover marker responses to resistance exercise in young men.

OBJECTIVE: We investigated acute bone turnover marker (BTM) responses to high-intensity resistance exercise with and without whole-body vibration (WBV) in young men (n=10). METHODS: In this randomized crossover study, subjects performed 2 protocols separated by 2-week wash out periods: 1) resistance exercise only (RE) (3 sets 10 repetitions 80% 1RM for 9 exercises); and 2) WBV + RE (side-alternating vibration platform 5 intermittent, 1-minute bouts 20 Hz, 3.38 mm peak-to-peak displacement followed by RE). Fasting morning blood draws were taken before RE or WBV (PRE), immediately post RE (IP), and 30 minutes post RE (30P). WBV + RE also had a blood draw after the WBV exposure (POST WBV). Blood samples were analyzed for lactate, hematocrit, bone-specific alkaline phosphatase (Bone ALP, U/L), C-terminal telopeptide of type I collagen (CTX-I, ng/mL) and tartrate-resistant acid phosphatase 5b (TRAP5b, U/L). RESULTS: Lactate, hematocrit, and Bone ALP significantly increased (p<0.05) IP for both protocols. Bone resorption markers did not change during RE only. CTX-I significantly decreased POST WBV. TRAP5b increased POST WBV, then significantly decreased at 30P. CONCLUSIONS: Generally, BTM changes to RE only were not significant when adjusted for hemoconcentration. The WBV stimulus altered bone resorption marker but not bone formation marker responses.

Associations between pQCT-based fat and muscle area and density and DXA-based total and leg soft tissue mass in healthy women and men.

UNLABELLED: Peripheral Quantitative Computed Tomography (pQCT) can be used for muscle and fat area and density assessments. These may independently influence muscle and fat mass measurements from Dual Energy X-ray Absorptiometry (DXA). OBJECTIVE: To determine associations between pQCT-derived soft tissue density and area measures and DXA-derived soft tissue mass. METHODS: Linear regression models were developed based on BMI and calf fat and muscle cross-sectional area (FCSA and MCSA) and density measured by pQCT in healthy women (n=76) and men (n=82) aged 20-59 years. Independent variables for these models were leg and total bone-free lean mass (BFLM) and fat mass (FM) measured by DXA. RESULTS: Sex differences (p<0.01) were found in both muscle (Mean±SE: Women: 78.6±0.4; Men: 79.9±0.2 mg/cm(3)) and fat (Women: 0.8±0.4 Men: 9.1±0.6 mg/cm(3)) density. BMI, fat density, and age (R(2)=0.86, p<0.01) best accounted for the variability in total FM. FCSA, BMI, and fat density explained the variance in leg FM (R(2)=0.87, p<0.01). MCSA and muscle density explained the variance in total (R(2)=0.65, p<0.01) and leg BFLM (R(2)=0.70, p<0.01). CONCLUSION: Calf muscle and fat area and density independently predict lean and fat tissue mass.

Inter-limb musculoskeletal differences in competitive ten-pin bowlers: a preliminary analysis.

OBJECTIVES: To compare musculoskeletal characteristics of the loaded and non-loaded forearm and upper leg of competitive ten-pin bowlers. METHODS: 10 competitive bowlers (30.6∓6.8 yrs) had their areal bone mineral density (aBMD) and body composition measured with Dual Energy X-ray Absorptiometry (DXA). Volumetric bone mineral density (vBMD) and bone characteristics were assessed at 4% and 66% of the limb length of each radius and 50% of the limb length of each femur using a pQCT. Bone and muscle characteristics of the loaded and non-loaded limbs were compared and analyzed using paired t-tests. RESULTS: The loaded arm of competitive bowlers had significantly (p<0.05) greater bone free lean body mass (BFLBM) (5%) and ultra distal radius site (UD radius) aBMD (6.3%) compared to the non-loaded side. Cortical and trabecular vBMD was significantly (p<0.05) greater (1.3%, 4.8%) at the radius 66% and 4% sites in the loaded forearm, respectively. aBMD of the femoral neck, trochanter, and total hip were significantly greater (12.2-15.6%) in the slide leg. Total (5.2%) and cortical (9.2%) bone areas, total (8.2%) and cortical (8.7%) bone mineral content (BMC), and cortical wall thickness (9%) were significantly greater at the 50% femur site in the slide leg compared to the contralateral side. CONCLUSION: The femoral shaft of bowlers adapts by increasing bone area and cortical thickness without a change in vBMD, while the loaded radius adapts by increasing vBMD.

Dose-response effect of 40 weeks of resistance training on bone mineral density in older adults.

UNLABELLED: Resistance training is becoming popular for maintaining bone health. Previous studies examined high intensity exercise; we compared high and low intensity resistance training performed 2 or 3 days per week in older adults. We found positive bone density responses for the hip and spine for all types of resistance training. INTRODUCTION: This study determined the dose-response effect of resistance training on lumbar spine, proximal femur, and total body bone mineral density (BMD) in older men and women (55-74 years). METHODS: Subjects included 45 men and 79 women who were assigned to one of the following training groups: 1-high intensity (80% 1RM), 2 days/week (2HI); 2-low intensity (40% 1RM), 2 days/week (2LI); 3-high intensity (80% 1RM), 3 days/week (3HI); and 4-low intensity (40% 1RM), 3 days/week (3LI). Bone scans (dual energy X-ray absorptiometry) were performed at baseline and after 40 weeks of training. Muscular strength (1-repetition maximum) was assessed every 5 weeks. RESULTS: There were significant trial (p < 0.05) effects but no significant trial × training group interactions for the BMD sites. Spine, trochanter, and total hip BMD increased from baseline to 40 weeks; however, the total body BMD site decreased in the 3LI group. Men and women exhibited similar improvements for the trochanter and total hip sites but the percent change in the spine tended (p = 0.054) to be higher for men (1.8%) than women (0.4%). CONCLUSIONS: The resistance training programs, regardless of intensity and frequency, were effective in improving BMD of the proximal femur and lumbar spine but not the total body. Both men and women responded similarly for the hip sites but men show a greater response at the lumbar spine than women.

The effects of supplementation with creatine and protein on muscle strength following a traditional resistance training program in middle-aged and older men.

OBJECTIVES: Creatine and protein supplementation can enhance the training outcomes of young subjects, but it is not clear if there are benefits for older individuals. Therefore, the purpose of this study was to determine the effects of creatine and protein supplementation on strength gains following a traditional resistance training program for middle-aged and older men. DESIGN, SETTING, PARTICIPANTS: This study assessed changes in strength of men aged 48-72 years following 14 weeks of resistance training supplemented with creatine and/or protein. A double-blind, randomized, placebo-controlled design placed 42 males into one of four groups: Resistance Trained Placebo (RTP, n=10); Resistance Trained Creatine (RTCr, 5g Cr, n=10); Resistance Trained Protein (RTPr, 35g whey Pr, n=11); or Resistance Trained Creatine and Protein (RTCrPr, 5g Cr and 35g Pr, n=11). INTERVENTION: All groups trained 3 days per week for 14 weeks. The resistance training program was based on progressive overload. Training loads corresponded to 80% 1 RM (one repetition maximum strength), 3 sets of 8 repetitions for the following exercises: knee extension/knee flexion; bicep curl/tricep extension; military press; lat pull down; seated leg press; and bench press. MEASUREMENTS: 1 RM for each exercise and measures of lean body mass were assessed prior to and following the 14 week program. RESULTS: Each group significantly (p < 0.05) increased strength and lean body mass, however, there were no significant group effects or group X trial interactions. CONCLUSION: Resistance training in middle-aged and older men significantly increased muscular strength and added muscle mass with no additional benefits from creatine and/or protein supplementation.

Age comparisons of bone density and geometry in men.

OBJECTIVES: The purposes of this study were to examine tibia bone density and geometry in young and middle aged men, and to explore relationships between pQCT- and DXA-derived body composition variables. METHODS: Healthy males (18-30 years old, n=31; 50-64 years old, n=37) had their total body areal bone mineral density (aBMD) and body composition measured with Dual Energy X-ray Absorptiometry (DXA). Volumetric bone characteristics, muscle cross-sectional area (MCSA) and fat cross-sectional area (FCSA) of the leg were measured with peripheral Quantitative Computed Tomography (pQCT). RESULTS: Young men were significantly (p<0.05) lighter and had less fat mass than older men. Total volumetric BMD (vBMD) at 66% of the tibia length was significantly lower (p<0.05) in older men. Bone-free lean body mass values were useful predictors of total and cortical area and content (R(2)=0.338-0.467). MCSA was more predictive of leg BFLBM than total body BFLBM, and those relationships were stronger in older men. CONCLUSIONS: Differences in tibial bone area and density existed between young and middle-aged men, and relationships between pQCT- and DXA-derived body composition variables were age-dependent.

The effects of creatine and whey protein supplementation on body composition in men aged 48 to 72 years during resistance training.

OBJECTIVES: Creatine and whey protein are supplements believed to have an ergogenic effect. Very little is known regarding the effects of these dietary supplements in older men. The purpose of this study was to determine the effect of creatine and whey protein supplements, consumed independently and in combination, on total and regional body composition in middle-aged men during a resistance-training program. DESIGN, SETTING, PARTICIPANTS: Forty-two men were randomly assigned to four groups to receive supplements according to a double-blind protocol. Groups consumed their supplements three times per week immediately following their resistance training sessions. The groups were: 1) placebo (480 ml of Gatorade); 2) creatine (480 ml of Gatorade plus 5 grams of creatine); 3) whey protein (480 ml of Gatorade plus 35 grams of whey protein powder); and 4) whey protein/creatine (480 ml of Gatorade plus 5 grams of creatine and 35 grams of whey protein powder). All groups participated in resistance training 3 times per week for 14 weeks. MEASUREMENTS: At the beginning and end of the study, total and regional measures of body composition (DXA) and total (TBW), intracellular (ICW), and extracellular (ECW) body water (Multifrequency BIA) were measured and 3-day diet records were completed. RESULTS: There were significant training effects for regional arm fat (decrease), regional arm bone free-fat free mass (BF-FFM - increase), total body BF-FFM (increase), ICW (increase), and ECW (increase) but no significant group effects and only one significant group by training interaction (ECW). There were no significant changes for total calorie, carbohydrate, fat or protein intake for any of the groups from prestudy to post-study testing. CONCLUSION: The results from this study suggest that supplementation with creatine, whey protein, or a combination of creatine and whey protein, when combined with resistance training in middle-aged men, have no added benefit to changes that occur to body composition due to resistance training alone.

Effects of creatine supplementation on isometric force-time curve characteristics.

PURPOSE: To assess the effects of creatine monohydrate on isometric force-time curve parameters of sedentary college males aged 18-25 yr. METHODS: This double-blind study randomly assigned subjects to either a treatment (with creatine (Cr)) group (N = 11) or placebo group (P) (N = 8). The Cr group received 20 g x d(-1) of Cr for the first 5 d, in 5-g doses, four times daily (loading period) followed by a 5-g x d(-1) dose for the next 5 d (maintenance phase) and then no Cr ingestion for 7 d (washout period). Each 5-g dose was mixed with 250 mL of Gatorade. The P group received a placebo (cornstarch) following the exact same dosage regimen and protocol as the Cr group. All subjects were sedentary and had not used any nutritional supplements for 6 months before the study. Measurements of isometric force production of four muscle groups (elbow flexors and extensors; knee flexors and extensors) were characterized by a number of force-time parameters including strength (MF), time to maximal force (TMF), rate of force development (MRFD), and intermittent endurance (total impulse (TI) and percent force decrement (PFD)). Testing was done at pretreatment, after the 10-d loading and maintenance phases, and after the washout phase. RESULTS: Repeated measures ANOVA indicated no significant group effect for any muscle group concerning the maximal strength parameters and only two significant time effects for the knee flexors during MF and MRFD. Similarly, there were no significant group effects for any muscle group during the endurance trials; however, there was a significant time effect concerning TI for each muscle group tested. CONCLUSION: Our findings indicate that oral supplementation with creatine monohydrate in untrained males does not positively influence isometric strength but may enhance intermittent isometric muscular endurance.

Creatine supplementation during resistance training in college football athletes.

PURPOSE: This investigation assessed the effects of a 9-wk regimen of creatine monohydrate (Cr x H2O) supplementation coupled with resistance training on body composition and neuromuscular performance in NCAA Division I football athletes. METHODS: Twenty-five subjects were randomly assigned in a double-blind, randomized placebo-controlled design, to a treatment (Cr, N = 9), placebo (P, N = 8), or control group (C, N = 8). The Cr group received 20 g.d(-1) of creatine for the first 5 d in 5-g doses, four times daily, followed by 5 g.d(-1) for the remainder of the study. Each 5-g dose was mixed with 500 mL of glucose solution (Gatorade). The P group received a placebo (sodium phosphate monohydrate; NaH2PO4 x H2O) following the exact protocol as the Cr group. The C group received no supplementation. All subjects resistance trained 4 d.wk(-1). Measurements of neuromuscular performance and body composition were made pre- and post-training after supplementation while monitoring dietary intakes. RESULTS: Repeated measures ANOVA indicated significant differences occurred between the Cr group and the other two groups (P and C) for total body weight, lean body mass, cell hydration, strength, peak torque at 300 degrees.s(-1) knee flexion, percent torque decrement, and anaerobic power and capacity. However, percent body fat, peak torque during both knee flexion and extension at 60 and 180 degrees.s(-1), peak torque at 300 degrees.s(-1) during knee extension, global muscular strength (power clean), and extracellular fluid remained statistically unchanged for all groups. CONCLUSIONS: Our findings indicate that creatine, supplemented concurrently with resistance and anaerobic training, may positively affect cell hydration status and enhance performance variables further than augmentation seen with training alone.

Musculoskeletal responses to high- and low-intensity resistance training in early postmenopausal women.

PURPOSE: The purpose of this study was to compare the effects of a high-load (80%, 1-repetition maximum (RM), 8 reps) and a high-repetition (40%, 1-RM, 16 reps) resistance training protocol on muscular strength and bone mineral density (BMD) in early postmenopausal, estrogen-deficient women. The 6-month programs were matched initially for training volume (3 sets, 3 d x wk(-1)) for 12 exercises selected to specifically load the spine and hip. METHODS: Subjects included 25 women (41-60 yr) who were matched by spine BMD then randomly assigned to either the high-load (HL, N = 10), high-repetition (HR, N = 7), or control (C, N = 8) groups. Dietary calcium intakes were supplemented to approximately 1500 mg x d(-1). Total body, spine, and hip BMD (DXA, Lunar Model DPX-IQ), upper and lower body muscular strength, and biochemical markers of bone turnover were measured at baseline and after 6 months of training. RESULTS: There were no group differences in the baseline measures. Both training groups showed similar increases in biceps (20%) and rectus femoris (28-33%) cross-sectional areas, in lower body strength (approximately 30%) and in hip strength (37-40%). HL showed greater improvements in upper body strength (HL 25%, HR 16%). Neither training group experienced significant increases in spine or hip BMD, although the HL total body BMD tended to decrease (-1.1%+/-0.4, P = 0.054) after training. Osteocalcin tended to increase (P = 0.08) in all groups after training, and the % change in osteocalcin was positively related to % changes in the total hip (r = 0.41, P = 0.048) and the trochanter (r = 0.42, P = 0.04) BMD. CONCLUSION: The high-load and high-repetition resistance training protocols were both effective in improving muscular strength and size in postmenopausal women, indicating low-intensity resistance training can be beneficial for the muscular fitness in women for whom high-intensity exercise is contraindicated.

Validity of diagnostic ultrasound as a measure of delayed onset muscle soreness.

STUDY DESIGN: Repeated measures were taken to evaluate delayed onset muscle soreness (DOMS) following eccentric bicep contractions of the nondominant arm at 140% of 1 repetition maximum (RM) while the dominant arm served as control. OBJECTIVES: To explore the usefulness of a noninvasive method to assess delayed onset muscle soreness. BACKGROUND: Although many methods have been proposed to assess DOMS, most are somewhat subjective or require a blood sample. This study compared the assessment of DOMS following eccentric exercise using common assessment techniques with diagnostic ultrasound (US). METHODS AND MEASURES: Forty nonimpaired women (18-40 years) used a Cybex isotonic biceps curl machine to eccentrically lower, using their nondominant arm, 140% of their dominant arm 1 RM to induce muscle soreness. Four assessment methods, (1) goniometry assessing spontaneous muscle shortening (SMS); (2) subjective muscle soreness ratings (MSRs); (3) serum creatine kinase (CK); and (4) diagnostic US scans of muscle cross-sectional area (CSA), were conducted at 5 different assessment times: (1) pre-eccentric exercise; (2) postexercise; (3) 24 hours postexercise; (4) 48 hours postexercise; and (5) 72 hours postexercise. RESULTS: Significant differences existed across assessment times for 3 of the 4 assessment techniques, CK, SMS, and MSR. CONCLUSIONS: Previously published methodologies used to assess DOMS (CK, SMS, and MSR) were able to provide consistent and expected results relative to the onset and progression of soreness with a high degree of relatedness (r = 0.48-0.84). However, it appeared that the ability to assess muscle soreness by diagnostic US, as evidenced by intramuscular swelling, was limited. Thus, the technique was not sensitive enough to detect any statistically significant changes in muscle CSA.

Exercise interventions for osteoporosis prevention in postmenopausal women.

Osteoporosis is a bone disease associated with reduced bone mineral density resulting in debilitating bone fractures. According to the National Institutes of Health Women's Health Initiative, effective interventions for bone loss need to be developed. The osteogenic stimulus provided by weight-bearing exercise indicates it is an important lifestyle factor that can be used for prevention of bone loss. Prospective research studies have documented that both aerobic exercise and weight training can be effective in the maintenance and building of bone mineral density in postmenopausal women. Additional benefits of weight training include increased muscular strength, coordination, and balance which could decrease risk for falling and subsequent fractures.

Chromium picolinate effects on body composition and muscular performance in wrestlers.

PURPOSE: The purpose of this study was to assess the effects of 14 wk of chromium picolinate supplementation during the final 16 wk of a preseason resistance and conditioning program on body composition and neuromuscular performance in NCAA Division I wrestlers. During this phase of training, wrestlers are primarily interested in trying to improve physical performance and wrestling technique and are not engaged in severe, acute weight loss practices commonly employed before competition. METHODS: This double-blinded, randomized placebo-controlled study involved 20 wrestlers from the University of Oklahoma assigned to either a treatment group (Cr+3; N = 7; 20.4 yr +/- 0.1) receiving 200 micrograms chromium picolinate daily, a placebo group (P; N = 7; 19.9 yr +/- 0.2), or a control group (C; N = 6; 20.2 yr +/- 0.1) using a stratified random sampling technique based on weight classification. Body composition, neuromuscular performance, metabolic performance, and serum insulin and glucose were measured before and immediately following the supplementation and training period. RESULTS: Repeated measures ANOVA indicated no significant changes in body composition for any of the groups. Aerobic power increased significantly (P < 0.002) in all groups, independent of supplementation. There were significant trial and group x trial interactions for upper body endurance (P = 0.038) and relative bench press power (P = 0.050). Post-hoc analyses revealed that the C group increased upper body endurance (P = 0.006), but none of the pre- to post-test changes in bench press power were significant. CONCLUSIONS: These results suggest that chromium picolinate supplementation coupled with a typical preseason training program does not enhance body composition or performance variables beyond improvements seen with training alone.

Age-related variability in body composition methods for assessment of percent fat and fat-free mass in men aged 20-74 years.

INTRODUCTION: Assessing body composition is important because of the association between excess body fat or obesity and the increased risk for coronary artery disease, diabetes, hyperlipidaemia and hypertension. Methodological differences among indirect body composition techniques are a source of variability that can affect estimations of fat-free mass (FEM) or percent fat, especially for different age groups. PURPOSE: This study examined the effect of age on the estimation of body composition by three methods based on the two-component model. One hundred and fifty-three men were placed into 5-year age groups from 20-24 to 70-74 years. Body composition was assessed by hydrodensitometry (underwater weighing; 40K spectroscopy (K40) and anthropometry. RESULTS: Day-to-day reliability was excellent for each method. Correlation coefficients between methods, independent of age, ranged from r= 0.71 (K40 and UWW) to r = 0.83 (UWW and anthropometry) for% fat and from r = 0.76 (K40 and anthropometry) to r = 0.90 (UWW and anthropometry) for FFM. Correlations between techniques weakened and showed greater variability as age increased. UWW produced the highest % fat and lowest FFM for the different age groups, while K40 and anthropometry yielded similar body composition values. All three methods detected age-related differences in % fat; however, only UWW determined a significant age effect in FFM. The greatest discrepancies between the methods occurred for the oldest age groups (60-74 years), but noticeable differences began occurring after the age of 40. CONCLUSIONS: Each method produced reliable data. Care should be taken when choosing any method based on the two-component model, especially when different age groups are being examined, since estimating % fat and FFM is dependent on the age-related chemical composition of an individual and the limitations of each method.

Antibiotics and respiratory infections: do antibiotic prescriptions improve outcomes?

BACKGROUND AND OBJECTIVES: Antibiotics are frequently prescribed for respiratory infections though most of these infections are viral. To determine whether this practice contributes to patient health and patient satisfaction, we studied the effect of antibiotic prescriptions on outcomes at 7 to 10 days. We also studied the effect of antibiotic prescriptions upon the accuracy of patients' beliefs about viruses. METHODS: One hundred thirteen patients with a respiratory infection completed questionnaires before and after their visit with their primary care doctor. A phone interview was completed 7 to 10 days later. Questions elicited their expectations for antibiotics, their beliefs about the efficacy of antibiotics, and satisfaction with the doctor. The phone interview asked whether they felt better, whether they had returned to the doctor about the same illness, satisfaction, and whether they would expect antibiotics for the same disease in the future. The doctors provided information about their diagnosis and treatment. RESULTS: No correlation was found between prescription of antibiotics and patient satisfaction, feeling better, return physician visits, or phone calls. Receiving antibiotics increased the likelihood the patients would expect antibiotics the next time they had an upper respiratory infection and made them more likely to have an inaccurate belief, that antibiotics kill viruses. CONCLUSIONS: The study found no evidence that antibiotics improve patient outcome in upper respiratory infections by making patients feel better at 7 to 10 days. Nor did it find evidence that antibiotics help physicians by reducing return visits or increasing patient satisfaction. Doctors are invited to reconsider their policies for prescribing antibiotics for upper respiratory infection.

Antibiotics and respiratory infections: are patients more satisfied when expectations are met?

BACKGROUND: Antibiotics are frequently prescribed for respiratory infections, even though most of these infections are viral. To understand why physicians do so, we studied patients' and physicians' expectations for antibiotics and the effects of the patient-physician interaction on patient satisfaction. METHODS: Patients with a respiratory infection were asked to complete a questionnaire before and after visiting with physicians at three family medicine centers. Physicians completed a questionnaire following the visit. RESULTS: Sixty-five percent of the 113 patients with respiratory infection expected antibiotics. Physicians had some ability to perceive this expectation and frequently prescribed antibiotics for patients who expected them. Antibiotics were prescribed to over 75% of patients with sinusitis or bronchitis and to 18% of those diagnosed with only viral infections. No association was found between a prescription for antibiotics and patient satisfaction; however, patient satisfaction did correlate with the patients' report that they understood the illness and that the physician spent enough time with them. CONCLUSIONS: Physicians frequently prescribe antibiotics for upper respiratory infections when they believe patients expect it, but receiving a prescription for antibiotics is not in and of itself associated with increased patient satisfaction.