Effect of intense military training on body composition

Individuals in a structural physical training program can show beneficial changes in body composition, such as body fat reduction and muscle mass increase. This study measured body composition changes by using 3 different techniques-skinfold thickness (SF) measurements, air displacement plethysmography (BOD-POD), and dual-energy x-ray absorptiometry (DXA)-during 9 months of intense training in healthy young men engaged in military training. Twenty-seven young men were recruited from a special faction of the Italian Navy. The program previewed three phases: ground combat, sea combat, and amphibious combat. Body composition was estimated at the beginning, in the middle, and at the end of the training. After the subjects performed the ground combat phase, body composition variables significantly decreased: body weight (P < 0.05), fat-free mass (FFM) (P < 0.001), and fat mass (FM) (P < 0.03). During the amphibious combat phase, body weight increased significantly (P < 0.01), mainly because of an increase in FFM (P < 0.001) and a smaller mean decrease in FM. There was a significant difference (P < 0.05) in circumferences and SF at various sites after starting the training course. Bland-Altman analysis did not show any systematic difference between FM and FFM measured with the 3 different techniques on any occasion. On any visit, FFM and FM correlation measured by BOD-POD (P = 0.90) and DXA was significantly greater than measured by SF. A significant difference was found in body mass index (BMI) measured during the study. BOD-POD and SF, compared with DXA, provide valid and reliable measurement of changes in body composition in healthy young men engaged in military training. In conclusion, the findings suggest that for young men of normal weight, changes in body weight alone and in BMI are not a good measure to assess the effectiveness of intense physical training programs, because lean mass gain can masquerade fat weight loss.     

Adipose tissue distribution in relation to insulin resistance in type 2 diabetes mellitus

Insulin resistance (IR) is typically more severe in obese individuals with type 2 diabetes (T2DM) than in similarly obese non-diabetics but whether there are group differences in body composition and whether such differences contribute to the more severe IR of T2DM is uncertain. DEXA and regional CT imaging were conducted to assess adipose tissue (AT) distribution and fat content in liver and muscle in 67 participants with T2DM (F39/M28, age 60 +/- 7 yr, BMI 34 +/- 3 kg/m(2)) and in 35 similarly obese, non-DM volunteers (F20/M15, age 55 +/- 8 yr, BMI 33 +/- 2 kg/m(2)). A biopsy of subcutaneous abdominal AT was done to measure adipocyte size. A glucose clamp was performed at an insulin infusion of 80 mU x min(-1) x m(-2). There was more severe IR in T2DM (6.1 +/- 2.3 vs. 9.9 +/- 3.3 mg x min(-1) x kg FFM(-1); P < 0.01). Group comparisons of body composition parameters was performed after adjusting for the effect of age, gender, race, height and total fat mass (FM). T2DM was associated with less leg FM (-1.2 +/- 0.4 kg, P < 0.01), more trunk FM (+1.1 +/- 0.4 kg, P < 0.05), greater hepatic fat (P < 0.05), and more subfascial adipose tissue around skeletal muscle (P < 0.05). There was a significant group x sex interaction for VAT (P < 0.01), with greater VAT in women with T2DM (P < 0.01). Mean adipocyte size (AS) did not significantly differ across groups, and smaller AS was associated with increased leg FM, whereas larger AS was related to more trunk FM (both P < 0.05). Group differences in IR were less after adjusting for group differences in leg FM, trunk FM, and hepatic fat, but these adjustments only partially accounted for the greater severity of IR in T2DM. In summary, T2DM, compared with similarly obese nondiabetic men and women, is associated with less leg FM and greater trunk FM and hepatic fat.     

Creatine supplementation influences substrate utilization at rest.

The influence of creatine supplementation on substrate utilization during rest was investigated using a double-blind crossover design. Ten active men participated in 12 wk of weight training and were given creatine and placebo (20 g/day for 4 days, then 2 g/day for 17 days) in two trials separated by a 4-wk washout. Body composition, substrate utilization, and strength were assessed after weeks 2, 5, 9, and 12. Maximal isometric contraction [1 repetition maximum (RM)] leg press increased significantly (P < 0.05) after both treatments, but 1-RM bench press was increased (33 +/- 8 kg, P < 0.05) only after creatine. Total body mass increased (1.6 +/- 0.5 kg, P < 0.05) after creatine but not after placebo. Significant (P < 0.05) increases in fat-free mass were found after creatine and placebo supplementation (1.9 +/- 0.8 and 2.2 +/- 0.7 kg, respectively). Fat mass did not change significantly with creatine but decreased after the placebo trial (-2.4 +/- 0.8 kg, P < 0.05). Carbohydrate oxidation was increased by creatine (8.9 +/- 4.0%, P < 0.05), whereas there was a trend for increased respiratory exchange ratio after creatine supplementation (0.03 +/- 0.01, P = 0.07). Changes in substrate oxidation may influence the inhibition of fat mass loss associated with creatine after weight training.     

Direct assessment of muscle glycogen storage after mixed meals in normal and type 2 diabetic subjects

To understand the day-to-day pathophysiology of impaired muscle glycogen storage in type 2 diabetes, glycogen concentrations were measured before and after the consumption of sequential mixed meals (breakfast: 190.5 g carbohydrate, 41.0 g fat, 28.8 g protein, 1253 kcal; lunch: 203.3 g carbohydrate, 48.1 g fat, 44.0 g protein, 1497.5 kcal) by use of natural abundance (13)C magnetic resonance spectroscopy. Subjects with diet-controlled type 2 diabetes (n = 9) and age- and body mass index-matched nondiabetic controls (n = 9) were studied. Mean fasting gastrocnemius glycogen concentration was significantly lower in the diabetic group (57.1 +/- 3.6 vs. 68.9 +/- 4.1 mmol/l; P < 0.05). After the first meal, mean glycogen concentration in the control group rose significantly from basal (97.1 +/- 7.0 mmol/l at 240 min; P = 0.005). After the second meal, the high level of muscle glycogen concentration in the control group was maintained, with a further rise to 108.0 +/- 11.6 mmol/l by 480 min. In the diabetic group, the postprandial rise was markedly lower than that of the control group (65.9 +/- 5.2 mmol/l at 240 min, P < 0.005, and 70.8 +/- 6.7 mmol/l at 480 min, P = 0.01) despite considerably greater serum insulin levels (752.0 +/- 109.0 vs. 372.3 +/- 78.2 pmol/l at 300 min, P = 0.013). This was associated with a significantly greater postprandial hyperglycemia (10.8 +/- 1.3 vs. 5.3 +/- 0.2 mmol/l at 240 min, P < 0.005). Basal muscle glycogen concentration correlated inversely with fasting blood glucose (r = -0.55, P < 0.02) and fasting serum insulin (r = -0.57, P < 0.02). The increment in muscle glycogen correlated with initial increment in serum insulin only in the control group (r = 0.87, P < 0.002). This study quantitates for the first time the subnormal basal muscle glycogen concentration and the inadequate glycogen storage after meals in type 2 diabetes.     

Decreased insulin action in skeletal muscle from patients with McArdle's disease

Insulin action is decreased by high muscle glycogen concentrations in skeletal muscle. Patients with McArdle's disease have chronic high muscle glycogen levels and might therefore be at risk of developing insulin resistance. In this study, six patients with McArdle's disease and six matched control subjects were subjected to an oral glucose tolerance test and a euglycemic-hyperinsulinemic clamp. The muscle glycogen concentration was 103 +/- 45% higher in McArdle patients than in controls. Four of six McArdle patients, but none of the controls, had impaired glucose tolerance. The insulin-stimulated glucose utilization and the insulin-stimulated increase in glycogen synthase activity during the clamp were significantly lower in the patients than in controls (51.3 +/- 6.0 vs. 72.6 +/- 13.1 micromol x min(-1) x kg lean body mass(-1), P < 0.05, and 53 +/- 15 vs. 79 +/- 9%, P < 0.05, n = 6, respectively). The difference in insulin-stimulated glycogen synthase activity between the pairs was significantly correlated (r = 0.96, P < 0.002) with the difference in muscle glycogen level. The insulin-stimulated increase in Akt phosphorylation was smaller in the McArdle patients than in controls (45 +/- 13 vs. 76 +/- 13%, P < 0.05, respectively), whereas basal and insulin-stimulated glycogen synthase kinase 3alpha and protein phosphatase-1 activities were similar in the two groups. Furthermore, the ability of insulin to decrease and increase fat and carbohydrate oxidation, respectively, was blunted in the patients. In conclusion, these data show that patients with McArdle's glycogen storage disease are insulin resistant in terms of glucose uptake, glycogen synthase activation, and alterations in fuel oxidation. The data further suggest that skeletal muscle glycogen levels play an important role in the regulation of insulin-stimulated glycogen synthase activity.     

Treatment with oxandrolone and the durability of effects in older men.

We investigated the effects of the anabolic androgen, oxandrolone, on lean body mass (LBM), muscle size, fat, and maximum voluntary muscle strength, and we determined the durability of effects after treatment was stopped. Thirty-two healthy 60- to 87-yr-old men were randomized to receive 20 mg oxandrolone/day (n = 20) or placebo (n = 12) for 12 wk. Body composition [dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging, and (2)H(2)O dilution] and muscle strength [1 repetition maximum (1 RM)] were evaluated at baseline and after 12 wk of treatment; body composition (DEXA) and 1-RM strength were then assessed 12 wk after treatment was discontinued (week 24). At week 12, oxandrolone increased LBM by 3.0 +/- 1.5 kg (P < 0.001), total body water by 2.9 +/- 3.7 kg (P = 0.002), and proximal thigh muscle area by 12.4 +/- 8.4 cm(2) (P < 0.001); these increases were greater (P < 0.003) than in the placebo group. Oxandrolone increased 1-RM strength for leg press by 6.7 +/- 6.4% (P < 0.001), leg flexion by 7.0 +/- 7.8% (P < 0.001), chest press by 9.3 +/- 6.7% (P < 0.001), and latissimus pull-down exercises by 5.1 +/- 9.1% (P = 0.02); these increases were greater than placebo. Oxandrolone reduced total (-1.9 +/- 1.0 kg) and trunk fat (-1.3 +/- 0.6 kg; P < 0.001), and these decreases were greater (P < 0.001) than placebo. Twelve weeks after oxandrolone was discontinued (week 24), the increments in LBM and muscle strength were no longer different from baseline (P > 0.15). However, the decreases in total and trunk fat were sustained (-1.5 +/- 1.8, P = 0.001 and -1.0 +/- 1.1 kg, P < 0.001, respectively). Thus oxandrolone induced short-term improvements in LBM, muscle area, and strength, while reducing whole body and trunk adiposity. Anabolic improvements were lost 12 wk after discontinuing oxandrolone, whereas improvements in fat mass were largely sustained.     

Oxidation of nonplasma fatty acids during exercise is increased in women with abdominal obesity.

We evaluated plasma fatty acid availability and plasma and whole body fatty acid oxidation during exercise in five lean and five abdominally obese women (body mass index = 21 +/- 1 vs. 38 +/- 1 kg/m(2)), who were matched on aerobic fitness, to test the hypothesis that obesity alters the relative contribution of plasma and nonplasma fatty acids to total energy production during exercise. Subjects exercised on a recumbent cycle ergometer for 90 min at 54% of their peak oxygen consumption. Stable isotope tracer methods ([(13)C]palmitate) were used to measure fatty acid rate of appearance in plasma and the rate of plasma fatty acid oxidation, and indirect calorimetry was used to measure whole body substrate oxidation. During exercise, palmitate rate of appearance increased progressively and was similar in obese and lean groups between 60 and 90 min of exercise [3.9 +/- 0.4 vs. 4.0 +/- 0.3 micromol. kg fat free mass (FFM)(-1). min(-1)]. The rate of plasma fatty acid oxidation was also similar in obese and lean subjects (12.8 +/- 1.7 vs. 14.5 +/- 1.8 micromol. kg FFM(-1). min(-1); P = not significant). However, whole body fatty acid oxidation during exercise was 25% greater in obese than in lean subjects (21.9 +/- 1.2 vs. 17.5 +/- 1.6 micromol. kg FFM(-1). min(-1); P < 0.05). These results demonstrate that, although plasma fatty acid availability and oxidation are similar during exercise in lean and obese women, women with abdominal obesity use more fat as a fuel by oxidizing more nonplasma fatty acids.     

Aging does not contribute to the decline in insulin action on storage of muscle glycogen in rats

Increase in fat mass (FM) and changes in body composition may account for the age-associated impairment in insulin action on muscle glycogen storage. We wish to examine whether preventing the increase in FM abolishes this defect seen with aging. We studied the novel aging model of F1 hybrids of BN/F344 NIA rats fed ad libitum (AL) at 2 (weighing 259+/-17 g), 8 (459+/-17 g), and 20 (492+/-10 g) mo old. To prevent the age-dependent growth in FM, rats were caloric restricted (CR) at 2 mo by decreasing their daily caloric intake by 45% (weighing 292+/-5 g at 8 mo, 294+/-9 g at 20 mo). As designed, the lean body mass (LBM) and %FM remained unchanged through aging (8 and 20 mo old) in the CR rats and was similar to that of 2-mo-old AL rats. However, 8- and 20-mo-old AL-fed rats had three- to fourfold higher FM than both CR groups. Peripheral insulin action at physiological hyperinsulinemia was determined (by 3 mU x kg(-1). min(-1) insulin clamp). Prevention of fat accretion maintained glucose uptake (R(d); 29+/-2, 29+/-2, and 31+/-4 mg x kg LBM(-1) x min(-1)) and glycogen synthesis rates (GS, 12+/-1, 12 +/-1, and 14+/-2 mg x kg LBM(-1) x min(-1)) at youthful levels (2 mo AL) in 8- and 20-mo-old CR rats, respectively. These levels were significantly increased (P<0.001) compared with AL rats with higher %FM (R(d), 22+/-1 and 22+/-2 and GS, 7+/-1 and 8+/-2 mg x kg LBM(-1). min(-1) in 8- and 20-mo-old rats, respectively). The increase in whole body GS in age-matched CR rats was accompanied by approximately 40% increased accumulation of [(3)H] glucose into glycogen and a similar increase in insulin-induced muscle glycogen content. Furthermore, the activation of glycogen synthase increased, i.e., approximately 50% decrease in the Michaelis constant, in both CR groups (P<0.01). We conclude that chronic CR designed to prevent an increase in storage of energy in fat maintained peripheral insulin action at youthful levels, and aging per se does not result in a defect on the pathway of glycogen storage in skeletal muscle.     

Ingestion of a high-glycemic index meal increases muscle glycogen storage at rest but augments its utilization during subsequent exercise.

The aim of this study was to compare the effect of preexercise breakfast containing high- and low-glycemic index (GI) carbohydrate (CHO) (2.5g CHO/kg body mass) on muscle glycogen metabolism. On two occasions, 14 days apart, seven trained men ran at 71% maximal oxygen uptake for 30 min on a treadmill. Three hours before exercise, in a randomized order, subjects consumed either isoenergetic high- (HGI) or low-GI (LGI) CHO breakfasts that provided (per 70 kg body mass) 3.43 MJ energy, 175 g CHO, 21 g protein, and 4 g fat. The incremental areas under the 3-h plasma glucose and serum insulin response curves after the HGI meal were 3.9- (P < 0.05) and 1.4-fold greater (P < 0.001), respectively, than those after the LGI meal. During the 3-h postprandial period, muscle glycogen concentration increased by 15% (P < 0.05) after the HGI meal but remained unchanged after the LGI meal. Muscle glycogen utilization during exercise was greater in the HGI (129.1 +/- 16.1 mmol/kg dry mass) compared with the LGI (87.9 +/- 15.1 mmol/kg dry mass; P < 0.01) trial. Although the LGI meal contributed less CHO to muscle glycogen synthesis in the 3-h postprandial period compared with the HGI meal, a sparing of muscle glycogen utilization during subsequent exercise was observed in the LGI trial, most likely as a result of better maintained fat oxidation.     

Effects of endurance exercise training on muscle glycogen accumulation in humans.

The purpose of this investigation was to determine whether endurance exercise training increases the ability of human skeletal muscle to accumulate glycogen after exercise. Subjects (4 women and 2 men, 31 +/- 8 yr old) performed high-intensity stationary cycling 3 days/wk and continuous running 3 days/wk for 10 wk. Muscle glycogen concentration was measured after a glycogen-depleting exercise bout before and after endurance training. Muscle glycogen accumulation rate from 15 min to 6 h after exercise was twofold higher (P < 0.05) in the trained than in the untrained state: 10.5 +/- 0.2 and 4.5 +/- 1.3 mmol. kg wet wt(-1). h(-1), respectively. Muscle glycogen concentration was higher (P < 0.05) in the trained than in the untrained state at 15 min, 6 h, and 48 h after exercise. Muscle GLUT-4 content after exercise was twofold higher (P < 0.05) in the trained than in the untrained state (10.7 +/- 1.2 and 4.7 +/- 0.7 optical density units, respectively) and was correlated with muscle glycogen concentration 6 h after exercise (r = 0.64, P < 0.05). Total glycogen synthase activity and the percentage of glycogen synthase I were not significantly different before and after training at 15 min, 6 h, and 48 h after exercise. We conclude that endurance exercise training enhances the capacity of human skeletal muscle to accumulate glycogen after glycogen-depleting exercise.     

Curcumin effects on inflammation and performance recovery following eccentric exercise-induced muscle damage

Downhill running is associated with fiber damage, inflammation, delayed-onset muscle soreness, and various functional deficits. Curcumin, a constituent of the Indian spice turmeric has been investigated for its anti-inflammatory activity and may offset some of the damage and functional deficits associated with downhill running. This study examined the effects of curcumin on inflammation and recovery of running performance following downhill running in mice. Male mice were assigned to downhill placebo (Down-Plac), downhill curcumin (Down-Cur), uphill placebo (Up-Plac), or uphill curcumin (Up-Cur) groups and run on a treadmill at 22 m/min at -14% or +14% grade, for 150 min. At 48 h or 72 h after the up/downhill run, mice (experiment 1) underwent a treadmill performance run to fatigue. Another subset of mice was placed in voluntary activity wheel cages following the up/downhill run (experiment 2) and their voluntary activity (distance, time and peak speed) was recorded. Additional mice (experiment 3) were killed at 24 h and 48 h following the up/downhill run, and the soleus muscle was harvested for analysis of inflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), and plasma was collected for creatine kinase analysis. Downhill running decreased both treadmill run time to fatigue (48 h and 72 h) and voluntary activity (24 h) (P < 0.05), and curcumin feedings offset these effects on running performance. Downhill running was also associated with an increase in inflammatory cytokines (24 h and 48 h) and creatine kinase (24 h) (P < 0.05) that were blunted by curcumin feedings. These results support the hypothesis that curcumin can reduce inflammation and offset some of the performance deficits associated with eccentric exercise-induced muscle damage.     

Weight loss in postmenopausal obesity: no adverse alterations in body composition and protein metabolism

We sought to determine if decrements in the mass of fat-free body mass (FFM) and other lean tissue compartments, and related changes in protein metabolism, are appropriate for weight loss in obese older women. Subjects were 14 healthy weight-stable obese (BMI > or =30 kg/m(2)) postmenopausal women >55 yr who participated in a 16-wk, 1, 200 kcal/day nutritionally complete diet. Measures at baseline and 16 wk included FFM and appendicular lean soft tissue (LST) by dual-energy X-ray absorptiometry; body cell mass (BCM) by (40)K whole body counting; total body water (TBW) by tritium dilution; skeletal muscle (SM) by whole body MRI; and fasting whole body protein metabolism through L-[1-(13)C]leucine kinetics. Mean weight loss (+/-SD) was 9.6+/-3.0 kg (P<0.0001) or 10.7% of initial body weight. FFM decreased by 2.1+/-2.6 kg (P = 0.006), or 19.5% of weight loss, and did not differ from that reported (2.3+/-0.7 kg). Relative losses of SM, LST, TBW, and BCM were consistent with reductions in body weight and FFM. Changes in [(13)C]leucine flux, oxidation, and synthesis rates were not significant. Follow-up of 11 subjects at 23.7 +/-5.7 mo showed body weight and fat mass to be below baseline values; FFM was nonsignificantly reduced. Weight loss was accompanied by body composition and protein kinetic changes that appear appropriate for the magnitude of body mass change, thus failing to support the concern that diet-induced weight loss in obese postmenopausal women produces disproportionate LST losses.     

Birth weight and body composition in overweight Latino youth: a longitudinal analysis

To examine the associations between birth weight and BMI, and total body composition, in overweight Latino adolescents. Two hundred and forty-two overweight Latino children (baseline age = 11.1 +/- 1.7 years; BMI >or= 85th percentile) were measured annually for up to 6 years (2.6 +/- 1.4 observations/child, total 848 visits). Birth weight and history of gestational diabetes were obtained by parental interview. Visceral fat and subcutaneous abdominal fat were assessed by magnetic resonance imaging, while total body fat, total lean tissue mass (LTM), trunk fat, and lean tissue trunk mass were measured by dual-energy X-ray absorptiometry. BMI and BMI percentile were calculated using the Centers for Disease Control and Prevention age appropriate cutoffs. Longitudinal linear mixed effects (LME) modeling was used to evaluate the influence of birth weight on subsequent changes in body composition and distribution of fat across puberty. Birth weight significantly predicted BMI (P < 0.001), total trunk fat (P < 0.001), total trunk LTM (P < 0.001), total fat mass (FM) (P < 0.001), and total LTM (P < 0.001), but not subcutaneous (P = 0.534) or visceral fat (P = 0.593) at age 11 years. Longitudinally, as participants transitioned into puberty, birth weight did not significantly predict any of the body composition or fat distribution measures (P > 0.05). Birth weight is significantly associated with increased adiposity and LTM and negatively associated with trunk fat mass and trunk lean mass at baseline; however these relationships did not predict rate of change of any of the variables as the children progress through adolescence.     

Effect of carbohydrate ingestion on metabolism during running and cycling.

The effects of carbohydrate or water ingestion on metabolism were investigated in seven male subjects during two running and two cycling trials lasting 60 min at individual lactate threshold using indirect calorimetry, U-14C-labeled tracer-derived measures of the rates of oxidation of plasma glucose, and direct determination of mixed muscle glycogen content from the vastus lateralis before and after exercise. Subjects ingested 8 ml/kg body mass of either a 6.4% carbohydrate-electrolyte solution (CHO) or water 10 min before exercise and an additional 2 ml/kg body mass of the same fluid after 20 and 40 min of exercise. Plasma glucose oxidation was greater with CHO than with water during both running (65 +/- 20 vs. 42 +/- 16 g/h; P < 0.01) and cycling (57 +/- 16 vs. 35 +/- 12 g/h; P < 0.01). Accordingly, the contribution from plasma glucose oxidation to total carbohydrate oxidation was greater during both running (33 +/- 4 vs. 23 +/- 3%; P < 0.01) and cycling (36 +/- 5 vs. 22 +/- 3%; P < 0.01) with CHO ingestion. However, muscle glycogen utilization was not reduced by the ingestion of CHO compared with water during either running (112 +/- 32 vs. 141 +/- 34 mmol/kg dry mass) or cycling (227 +/- 36 vs. 216 +/- 39 mmol/kg dry mass). We conclude that, compared with water, 1) the ingestion of carbohydrate during running and cycling enhanced the contribution of plasma glucose oxidation to total carbohydrate oxidation but 2) did not attenuate mixed muscle glycogen utilization during 1 h of continuous submaximal exercise at individual lactate threshold.     

Whole body leucine flux in HIV-infected patients treated with or without protease inhibitors

The present study was carried out to assess the effects of protease inhibitor (PI) therapy on basal whole body protein metabolism and its response to acute amino acid-glucose infusion in 14 human immunodeficiency virus (HIV)-infected patients. Patients treated with PIs (PI+, 7 patients) or without PIs (PI-, 7 patients) were studied after an overnight fast during a 180-min basal period followed by a 140-min period of amino acid-glucose infusion. Protein metabolism was investigated by a primed constant infusion of l-[1-(13)C]leucine. Dual-energy X-ray absorptiometry for determination of fat-free mass (FFM) and body fat mass measured body composition. In the postabsorptive state, whole body leucine balance was 2.5 times (P < 0.05) less negative in the PI+ than in the PI- group. In HIV-infected patients treated with PIs, the oxidative leucine disposal during an acute amino acid-glucose infusion was lower (0.58 +/- 0.09 vs. 0.81 +/- 0.07 micromol x kg FFM(-1) x min(-1) using plasma [(13)C]leucine enrichment, P = 0.06; or 0.70 +/- 0.10 vs. 0.99 +/- 0.08 micromol x kg FFM(-1) x min(-1) using plasma [(13)C]ketoisocaproic acid enrichment, P = 0.04 in PI+ and PI- groups, respectively) than in patients treated without PIs. Consequently, whole body nonoxidative leucine disposal (an index of protein synthesis) and leucine balance (0.50 +/- 0.10 vs. 0.18 +/- 0.06 micromol x kg FFM x (-1) x min(-1) in PI+ and PI- groups respectively, P < 0.05) were significantly improved during amino acid-glucose infusion in patients treated with PIs. However, whereas the response of whole body protein anabolism to an amino acid-glucose infusion was increased in HIV-infected patients treated with PIs, any improvement in lean body mass was detected.     

Changes in power assessed by the Wingate Anaerobic Test following downhill running

Few studies have examined the effects of eccentric exercise-induced muscle damage on power despite power being a key performance variable in a number of sporting events. The aim of this study was to examine changes in anaerobic power (30-second Wingate Test), isometric strength of the knee extensors and flexors, muscle soreness, and plasma creatine kinase (CK) activity following downhill running. Eight men performed a 40-minute downhill (-7%) run on a treadmill, and measurements were taken on 6 occasions (2 baseline and 0.5, 24, 72, and 120 hours postrun). A second group of men (n = 5) had the measurements taken on 6 occasions without downhill running and served as a control group. A repeated measures analysis of variance revealed no significant changes in any measures across time for the control group. Following downhill running, significant (p < 0.05) decreases in strength (0.5-24 hours), and significant increases in muscle soreness (0.5-72 hours) and plasma CK activity (0.5-120 hours) were observed. A significant decrease in peak and average power (approximately 5%) was evident only 0.5 hours postrun, and the decrease was smaller in magnitude than that of strength (approximately 15%). These results suggest that power is less affected than strength after eccentric exercise, and the effect of reduced power on sport performance seems negligible.     

Effects of an oral androgen on muscle and metabolism in older,community-dwelling men

To determine whether oxymetholone increases lean body mass (LBM) and skeletal muscle strength in older persons, 31 men 65-80 yr of age were randomized to placebo (group 1) or 50 mg (group 2) or 100 mg (group 3) daily for 12 wk. For the three groups, total LBM increased by 0.0 +/- 0.6, 3.3 +/- 1.2 (P < 0.001), and 4.2 +/- 2.4 kg (P < 0.001), respectively. Trunk fat decreased by 0.2 +/- 0.4, 1.7 +/- 1.0 (P = 0.018), and 2.2 +/- 0.9 kg (P = 0.005) in groups 1, 2, and 3, respectively. Relative increases in 1-repetition maximum (1-RM) strength for biaxial chest press of 8.2 +/- 9.2 and 13.9 +/- 8.1% in the two active treatment groups were significantly different from the change (-0.8 +/- 4.3%) for the placebo group (P < 0.03). For lat pull-down, 1-RM changed by -0.6 +/- 8.3, 8.8 +/- 15.1, and 18.4 +/- 21.0% for the groups, respectively (1-way ANOVA, P = 0.019). The pattern of changes among the groups for LBM and upper-body strength suggested that changes might be related to dose. Alanine aminotransferase increased by 72 +/- 67 U/l in group 3 (P < 0.001), and HDL-cholesterol decreased by -19 +/- 9 and -23 +/- 18 mg/dl in groups 2 and 3, respectively (P = 0.04 and P = 0.008). Thus oxymetholone improved LBM and maximal voluntary muscle strength and decreased fat mass in older men.     

Profiles of musculoskeletal development in limbs of college Olympic weightlifters and wrestlers

To investigate the event-related profiles of musculoskeletal development in weight-categorized athletes, we measured the cross-sectional areas (CSA) of bone and muscle in the forearm, upper arm, lower leg and thigh, using a B-mode ultrasound apparatus, in college Olympic weightlifters (OWL, n = 19) and wrestlers (WR, n = 17) and untrained men (UM, n = 24), whose body masses were within the range from 55 kg to 78 kg. Both bone and muscle CSA at all sites were significantly correlated to the two-thirds power of fat-free mass (FFM(2/3)) with correlation coefficients of 0.430-40.741 (P < 0.05) and 0.608-0.718 (P < 0.05), respectively. Moreover, there were significant correlations between bone and muscle CSA at all sites (r = 0.664-0.829, P < 0.05). Even when bone and muscle CSA were expressed relative value to FFM(2/3), both OWL and WR showed significantly greater values than UM at all sites except for the lower leg. Furthermore, the comparison of the lean (bone + muscle) CSA ratio from site to site indicated a higher distribution of lean tissues in the upper extremities in OWL and WR compared to UM. While there was no significant difference between the two athlete groups in FFM(2/3), OWL showed significantly larger values than WR in the bone CSA of the upper arm and thigh and in the muscle CSA of the lower leg and thigh. However, lean CSA ratios of the upper extremities to the lower ones were significantly higher in WR than in OWL. Thus, the present results indicated that, compared to UM, OWL and WR had a greater lean tissue CSA in limbs, especially in the upper extremities, even when the difference in FFM was normalized. Moreover, the relative distribution of lean tissues in limbs differed between the two weight-categorized athletes in spite of there being no difference in FFM, which may be attributable to their own training regimens and/or competition style.     

Influences of calorie restriction and age on energy expenditure in the rhesus monkey

Caloric restriction (CR) is known to retard the aging process, and a marker of aging is decreased energy expenditure (EE). To assess longitudinal effects of CR on EE in rhesus monkeys (Macaca mulatta), data from 41 males (M) and 26 females (F) subjected to 9 or 15 yr of CR were studied. EE and body composition of monkeys 11-28 yr of age were measured using indirect calorimetry and dual X-ray absorptiometry. Total EE (24-h EE) was divided into daytime (day EE), nighttime (night EE), and daytime minus nighttime (D - N EE). M calorie-restricted monkeys showed a lower 24-h EE (means +/- SD = 568 +/- 96 kcal/day, P < 0.0001) than controls (C; 630 +/- 129 kcal/day). Calorie-restricted M had a lower night EE (difference = 36 kcal P < 0.0001) compared with C M, but after adjusting for FFM and FM, night EE was not different between calorie-restricted and C males (P = 0.72). The 24-h EE decreased with age (13 kcal decrease/yr, P < 0.0001), but there was no difference between CR and C. Adjusted for FFM and FM, D - N EE decreased with age (9 kcal/yr, P < 0.0001), with no interaction with age (P = 0.72). The F were compared with age-matched M selected from the male cohort. F had a lower 24-h EE (496 +/- 84 kcal/day) than M (636 +/- 139 kcal/day) (P < 0.0001). Adjusting for FFM and FM, night EE was lower in F compared with M (difference = 18 kcal, P = 0.077). Night EE did not differ between calorie-restricted and C younger monkeys after adjusting for FFM and FM. In conclusion, CR did not alter the age-related decrease in EE with CR.     

Creatine monohydrate and conjugated linoleic acid improve strength and body composition following resistance exercise in older adults

Aging is associated with lower muscle mass and an increase in body fat. We examined whether creatine monohydrate (CrM) and conjugated linoleic acid (CLA) could enhance strength gains and improve body composition (i.e., increase fat-free mass (FFM); decrease body fat) following resistance exercise training in older adults (>65 y). Men (N = 19) and women (N = 20) completed six months of resistance exercise training with CrM (5g/d)+CLA (6g/d) or placebo with randomized, double blind, allocation. Outcomes included: strength and muscular endurance, functional tasks, body composition (DEXA scan), blood tests (lipids, liver function, CK, glucose, systemic inflammation markers (IL-6, C-reactive protein)), urinary markers of compliance (creatine/creatinine), oxidative stress (8-OH-2dG, 8-isoP) and bone resorption (Nu-telopeptides). Exercise training improved all measurements of functional capacity (P<0.05) and strength (P<0.001), with greater improvement for the CrM+CLA group in most measurements of muscular endurance, isokinetic knee extension strength, FFM, and lower fat mass (P<0.05). Plasma creatinine (P<0.05), but not creatinine clearance, increased for CrM+CLA, with no changes in serum CK activity or liver function tests. Together, this data confirms that supervised resistance exercise training is safe and effective for increasing strength in older adults and that a combination of CrM and CLA can enhance some of the beneficial effects of training over a six-month period. Trial Registration. ClinicalTrials.gov NCT00473902.