Resistance exercise augments the acute anabolic effects of intradialytic oral nutritional supplementation.

BACKGROUND: An intriguing strategy to further enhance the anabolic effects of nutritional supplementation is to combine the administration of nutrients with resistance exercise. We hypothesized that the addition of resistance exercise to oral nutrition supplementation would lead to further increases in skeletal muscle protein accretion when compared to nutritional supplementation alone in chronic haemodialysis (CHD) patients. METHODS: We performed stable isotope protein kinetic studies in eight CHD patients during two separate settings: with oral nutritional supplementation alone (PO) and oral nutritional supplementation combined with a single bout of resistance exercise (PO + EX). Metabolic assessment was performed before, during and after haemodialysis. Both interventions resulted in robust protein anabolic response. RESULTS: There were no differences in metabolic hormones, plasma amino acid and whole-body protein balance between the interventions. During the post-HD phase, PO + EX retained a positive total amino acid (TAA) balance (primarily due to essential amino acid) while PO returned to a negative TAA balance although this difference did not reach statistical significance (78 +/- 109 versus -128 +/- 72 nmol/100 ml/min, respectively; P = 0.69). In the post-HD phase, PO + EX had significantly higher net muscle protein balance when compared to PO (19 +/- 16 versus -24 +/- 10 microg/100 ml/min, respectively; P = 0.036) We conclude that a single bout of resistance exercise augments the protein anabolic effects of oral intradialytic nutritional supplementation when examining skeletal muscle protein turnover.

Body composition and physical activity in end-stage renal disease.

OBJECTIVE: The study objective was to examine the relationship between visceral and somatic protein stores and physical activity in individuals with end-stage renal disease. DESIGN: This was a prospective single-center study. SETTING: The study took place at the Vanderbilt University Outpatient Dialysis Unit and General Clinical Research Center. PATIENTS: Fifty-five patients with prevalent chronic hemodialysis (CHD) were included: 33 males, 22 females, 45 African Americans, 9 Caucasians, and 1 Asian. The mean age was 47.0 +/- 1.6 years, height was 166.4 +/- 13.9 cm, and weight was 83.1 +/- 2.6 kg. METHODS: Body composition was measured by dual-energy x-ray absorptiometry. Minute-by-minute physical activity was assessed over a 7-day period with a triaxial accelerometer. Participants were interviewed by a trained registered dietitian for two 24-hour diet recalls (one from a hemodialysis day; one from a nonhemodialysis day). Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and creatinine were also collected. MAIN OUTCOME MEASURE: Predictors of somatic protein stores were the main outcome measure. RESULTS: Serum albumin was negatively and significantly correlated with the percentage of fat mass (P = .016) and kg of fat mass (P = .044). C-reactive protein was positively and significantly correlated with body weight (P = .006), percentage of fat mass (P = .017), kg of fat mass (P = .006), and body mass index (P = .004). Physical activity and total daily protein intake were the strongest predictors of the amount of lean body mass (P = .01 and .003, respectively). CONCLUSION: The association between somatic protein and visceral protein stores is weak in patients with CHD. Whereas increased levels of physical activity and total daily protein intake are associated with higher lean body mass in patients with CHD, higher adiposity is associated with higher C-reactive protein and lower albumin values.

Physical activity patterns in chronic hemodialysis patients: comparison of dialysis and nondialysis days.

OBJECTIVE: To determine physical activity patterns in chronic hemodialysis patients with a specific emphasis on the difference between dialysis and nondialysis days. Design A cross-sectional single-center study. SETTING: Vanderbilt University Outpatient Dialysis Unit. PATIENTS: Twenty current chronic hemodialysis patients: 10 male, 10 female; 15 black, 5 white; mean age, 50.1 +/- 9.9 years; height, 164.5 +/- 10.9 cm; weight, 82.5 +/- 15.4 kg; length on dialysis, 57.3 +/- 45.3 months. METHODS: Minute-by-minute physical activity was assessed over a 7-day period using a triaxial accelerometer, which consists of raw numbers or counts calculated by the 3 axes of the accelerometer (PA counts). PA counts were extrapolated on a daily and hourly basis. Physical functioning tests included: sit-to-stand, 6-minute walk, and 1-repetition maximal leg press exercise. Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and cholesterol were also collected. MAIN OUTCOME MEASURE: PA counts. RESULTS: Total PA counts were significantly lower on dialysis days when compared with nondialysis days (128,279 +/- 74,009 versus 168,744 +/- 95,168, respectively, P = .025). The average PA counts during the 4-hour dialysis time period were significantly lower on dialysis days when compared with nondialysis days (3,086 +/- 3,749 versus 11,070 +/- 7,695, respectively, P = .001). At postdialysis hours 1 and 2, PA counts on dialysis days were significantly higher than on nondialysis days (11,410 +/- 5,340 versus 9,082 +/- 6,646, P = .008, and 14,048 +/- 9,728 versus 8,662 +/- 6,433, P = .016, respectively). By postdialysis hour 4, PA counts on dialysis days had significantly decreased when compared with nondialysis days (6,068 +/- 6,268 versus 10,512 +/- 7,420 PA counts, P = .01, respectively). From postdialysis hours 5 to 20, there was no significant difference in PA counts between dialysis and nondialysis days. CONCLUSION: This study shows that physical activity is lower on dialysis days when compared with nondialysis days, and this decrease is caused by the lack of activity during the 4-hour hemodialysis procedure. New behavior modification strategies involving physical activity, both during hemodialysis and on nondialysis days, must be examined in this patient population.

Seasonal changes in amount and patterns of physical activity in women.

BACKGROUND: Environmental factors including seasonal changes are important to guide physical activity (PA) programs to achieve or sustain weight loss. The goal was to determine seasonal variability in the amount and patterns of free-living PA in women. METHODS: PA was measured in 57 healthy women from metropolitan Nashville, TN, and surrounding counties (age: 20 to 54 years, body mass index: 17 to 48 kg/m2) using an accelerometer for 7 consecutive days during 3 seasons within 1 year. PA counts and energy expenditure (EE) were measured in a whole-room indirect calorimeter and used to model accelerometer output and to calculate daily EE and intensity of PA expressed as metabolic equivalents (METs). RESULTS: PA was lower in winter than in summer (131+/-45 vs. 144+/-54x10(3) counts/d; P=.025) and in spring/fall (143+/-48x10(3) counts/d; P=.027). On weekends, PA was lower in winter than in summer by 22,652 counts/d (P=.008). In winter, women spent more time in sedentary activities than in summer (difference 35 min/d; P=.007) and less time in light activities (difference -29 min/d, P=.018) and moderate or vigorous activities (difference -6 min/d, P=.051). CONCLUSIONS: Women living in the southeastern United States had lower PA levels in winter compared with summer and spring/fall, and the magnitude of this effect was greater on weekends than weekdays.

Intradialytic oral nutrition improves protein homeostasis in chronic hemodialysis patients with deranged nutritional status.

Decreased dietary protein intake and hemodialysis (HD)-associated protein catabolism predispose chronic HD (CHD) patients to deranged nutritional status, which is associated with poor clinical outcome in this population. Intradialytic parenteral nutrition (IDPN) reverses the net negative whole-body and skeletal muscle protein balance during HD. IDPN is costly and restricted by Medicare and other payers. Oral supplementation (PO) is a more promising, physiologic, and affordable intervention in CHD patients. Protein turnover studies were performed by primed-constant infusion of L-(1-(13)C) leucine and L-(ring-(2)H(5)) phenylalanine in eight CHD patients with deranged nutritional status before, during, and after HD on three separate occasions: (1) with IDPN infusion, (2) with PO administration, and (3) with no intervention (control). Results showed highly positive whole-body net balance during HD for both IDPN and PO (4.43 +/- 0.7 and 5.71 +/- 1.2 mg/kg fat-free mass per min, respectively), compared with a neutral balance with control (0.25 +/- 0.5 mg/kg fat-free mass per min; P = 0.002 and <0.001 for IDPN versus control and PO versus control, respectively). Skeletal muscle protein homeostasis during HD also improved with both IDPN and PO (50 +/- 19 and 42 +/- 17 microg/100 ml per min) versus control (-27 +/- 13 microg/100 ml per min; P = 0.005 and 0.009 for IDPN versus control and PO versus control, respectively). PO resulted in persistent anabolic benefits in the post-HD phase for muscle protein metabolism, when anabolic benefits of IDPN dissipated (-53 +/- 25 microg/100 ml per min for control, 47 +/- 41 microg/100 ml per min for PO [P = 0.039 versus control], and -53 +/- 24 microg/100 ml per min for IDPN [P = 1.000 versus control and 0.039 versus PO]). Long-term studies using intradialytic oral supplementation are needed for CHD patients with deranged nutritional status.

Metabolic syndrome as a risk factor for contrast-induced nephropathy in non-diabetic elderly patients with renal impairment.

BACKGROUND/AIMS: Metabolic syndrome (MS) as a risk factor for contrast-induced nephropathy (CIN) has not been studied. The aim of the present study was to assess the influence of MS on the development of CIN in patients undergoing coronary angiography. METHODS: This was a prospective cohort study. A total of 219 non-diabetic patients with reduced kidney function and age >or=60 years were divided into two groups (MS, n = 107 and non-MS, n = 112). CIN was defined as an increase of >or=25% in creatinine over the baseline value within 48 h of angiography. RESULTS: CIN occurred in 14% of the MS group and 3.6% of the non-MS group (p = 0.006). Serum creatinine increased from 1.06 +/- 0.17 to 1.12 +/- 0.27 mg/dl in the MS group and from 1.03 +/- 0.17 to 1.09 +/- 0.23 mg/dl in the non-MS group (p < 0.001). MS was a risk indicator of CIN [odds ratio (OR) 4.26; 95% confidence interval (95% CI) 1.19-15.25; p = 0.026). Impaired fasting glucose (OR 4.72; 95% CI 1.53-14.56; p = 0.007), high triglyceride (OR 4.06; 95% CI 1.22-13.44; p = 0.022), and multivessel involvement (OR 3.14; 95% CI 1.07-9.82; p = 0.038) in the MS group were predictors of CIN. CONCLUSION: Our data support the hypothesis that patients with MS are at risk of developing CIN.

Increased muscle protein breakdown in chronic hemodialysis patients with type 2 diabetes mellitus.

BACKGROUND: The presence of diabetes mellitus (DM) in chronic hemodialysis (CHD) patients has potential to increase body protein losses and muscle wasting. METHODS: In this study, we examined whole-body and skeletal muscle protein metabolism in 6 CHD patients with type 2 (T2) DM (2 male, 44.4 +/- 6.1 years old, 2 white/4 African American HbA(1)C = 9.5 +/- 1.1%), and 6 non-DM CHD patients (2 male, 43.3 +/- 6.7 years old, 2 white/4 African American) in a fasting state, using a primed-constant infusion of L-(1-(13)C) leucine and L-(ring-(2)H(5)) phenylalanine. RESULTS: CHD patients with T2DM had significantly increased (83%) skeletal muscle protein breakdown (137 +/- 27 vs. 75 +/- 25 microg/100 mL/min). There was no significant difference in muscle protein synthesis between groups (78 +/- 27 vs. 66 +/- 21 microg/100 mL/min, for DM and non-DM respectively), resulting in significantly more negative net protein balance in the muscle compartment in the DM group (-59 +/- 4 vs. -9 +/- 6 microg/100 mL/min, P < 0.05). A similar trend was observed in whole-body protein synthesis and breakdown. Plasma glucose levels were 113 +/- 16 and 71 +/- 2 mg/dL, P < 0.05, and insulin levels were 25.3 +/- 9.6 and 7.3 +/- 1.0 uU/mL, for DM versus non-DM, respectively, P < 0.05. No significant differences between DM and non-DM were found in other metabolic hormones. CONCLUSION: The results of this study demonstrate that CHD patients with T2DM under a suboptimal metabolic control display accelerated muscle protein loss compared with a matched group of non-DM CHD patients.

Use of air displacement plethysmography in the determination of percentage of fat mass in african american children.

The purpose of this study was to determine the ability of air displacement plethysmography (ADP) to estimate percentage of fat mass (%FM) in African American children. %FM was determined in 21 boys and 13 girls (11.0 +/- 1.4 y, 18.6 +/- 4.2 kg/m(2) [mean +/- SD]) by ADP (using six published densitometric equations) and dual-energy x-ray absorptiometry (DXA). Measures were done within 2 h of one another, in random order. Regardless of equation, %FM(ADP) was significantly correlated with %FM(DXA) (R(2) = 0.67-0.71, all p < 0.001). %FM(ADP) using the equation of Siri (%FM(ADP-Siri) 20.3 +/- 9.0) agreed most closely with %FM(DXA) (20.0 +/- 10.2, difference p = 0.729). Together, surface area artifact and bone mineral content per unit of bone-free fat-free mass accounted for 29% of the variance in the residual between methods. The correlation between %FM(ADP-Siri) and %FM(DXA) was not significant for those <35 kg (n = 10; R(2) = 0.084, p = 0.417). There was a trend toward %FM(ADP-Siri) underestimating %FM(DXA) in girls (-1.46 +/- 3.0%FM; p = 0.103) but not in boys (1.43 +/- 6.4%FM; p = 0.315). Predicted lung volume was 40.1% higher than measured lung volume (p < 0.001). %FM(ADP-Siri) determined using predicted lung volume was 23.5 +/- 8.9, higher than that using measured lung volume (p < 0.001) and higher than %FM(DXA) (p = 0.001). We conclude that in 9- to 14-y-old African American children and provided lung volume is measured, %FM using ADP with Siri's equation approximates that obtained by DXA. Body composition results determined by ADP in children <35 kg should be interpreted with caution.