Biomedical subjects

Wayne W Campbell

Publications and source records attributed to Wayne W Campbell.

At least 19 recordsLinked to original sources

PubMed2006

Energy restriction with different protein quantities and source: implications for innate immunity.

OBJECTIVE: Physical age, energy restriction (ER), and weight loss have been reported to suppress indices of innate immunity, which may increase the risk of illness. To evaluate these interactions, we recruited older, postmenopausal women (50 to 80 years) to fill one of the following 9-week ER (1250 kcal/d) groups: beef [n = 14; reported intakes 46% carbohydrate (CHO):24% protein (PRO):30% fat], chicken (n = 15; 51% CHO:25% PRO:24% fat), or CHO (n = 14; 59% CHO:17% PRO:24% fat), or a non-intervention control (n = 11). RESEARCH METHODS AND PROCEDURES: Fasting blood was collected before and after ER to determine leukocyte phenotype, neutrophil oxidative burst capacity, natural killer cell activity, stimulated interleukin-2 and interferon-gamma production, and blood zinc and iron concentrations. RESULTS: No significant effects of ER (8.6% weight loss) or PRO quantity and source were found for the majority of indices of innate immunity. Small but significant (p < 0.05) declines in interleukin-2 production were found in the chicken and CHO groups only; however, the clinical significance of this finding is not known. DISCUSSION: In the present study, 9 weeks of moderate ER did not suppress immunity in postmenopausal women. Also, contrary to our hypothesis, differential zinc and iron intakes did not significantly alter immunity.

Aged↗

PubMed2006

Physical activity status, but not age, influences inflammatory biomarkers and toll-like receptor 4.

BACKGROUND: Chronic inflammation has been implicated in the development of cardiovascular disease, diabetes mellitus, cachexia, and osteoporosis. Regular physical activity has been purported to possess "anti-inflammatory" properties which may limit chronic inflammation. Recently, we hypothesized that toll-like receptor 4 (TLR4) may play a role in activity-induced modulation of inflammation. Therefore, the purpose of this study was to determine the association between age, physical activity status, biomarkers of inflammation, and TLR4. METHODS: Male and female participants (n = 84) were recruited to fill one of the following groups: young (18-30 years), active; young, inactive; old (60-80 years), active; or old, inactive. To assess physical activity status, participants completed a Paffenbarger Physical Activity Questionnaire and a modified Balke submaximal treadmill test. After grouping and screening, participants were given a standard mixed diet to consume 24 hours prior to arriving at the laboratory. Participants were instructed to consume all food by 10 pm the night prior to blood sampling (8-hour fast). Following 30 minutes of seated rest in a quiet room, venous blood samples were collected. Lipopolysaccharide-stimulated inflammatory cytokine production and plasma high-sensitivity C-reactive protein (hsCRP) were determined by enzyme-linked immunosorbent assay, and TLR4 expression was determined by flow cytometry. RESULTS: Lipopolysaccharide-stimulated interleukin-6, interleukin-1beta, and tumor necrosis factor-alpha production, TLR4 expression, and hsCRP were significantly lower in active compared to inactive participants (p <.05). Also, older participants had significantly higher hsCRP than young participants had (p <.05). CONCLUSIONS: The findings of the present study support previous reports which infer that acute exercise or a physically active lifestyle may possess anti-inflammatory properties. Also this study, along with previous work from our laboratory, suggests that TLR4 may play a role in regulating the link between inflammatory cytokine production and a physically active lifestyle.

Adult↗

PubMed2006

Modular protein supplements and their application to long-term care.

Modular protein supplements are added to either the diet or enteral formula to increase the protein or amino acid intakes of people who are nutritionally compromised. Protein supplements are aggressively marketed to long-term care clinicians because protein energy malnutrition and wounds are a common problem in this care setting. It can be challenging for clinicians to distinguish one product from another and to determine the best product for a specific application or nutrition care goal. Modular protein products can be sorted into 4 categories: (1) protein concentrates derived from a complete protein such as milk, soy, or eggs; (2) protein concentrates derived from collagen, either alone or in combination with a complete protein; (3) doses of 1 or more dispensable (nonessential) amino acids; and (4) hybrids of the complete or collagen-based proteins and amino acid dose. Modular protein supplements are generally provided either as a substrate for protein synthesis or as a source of 1 or more amino acids that may be conditionally indispensable (conditionally essential) under certain disease conditions. This review provides guidelines for the use of modular protein supplements according to their intended physiologic function and the assessment and nutrition care goals of the long-term care resident.

Amino Acids↗

PubMed2006

Vegetarian diets : nutritional considerations for athletes.

The quality of vegetarian diets to meet nutritional needs and support peak performance among athletes continues to be questioned. Appropriately planned vegetarian diets can provide sufficient energy and an appropriate range of carbohydrate, fat and protein intakes to support performance and health. The acceptable macronutrient distribution ranges for carbohydrate, fat and protein of 45-65%, 20-35% and 10-35%, respectively, are appropriate for vegetarian and non-vegetarian athletes alike, especially those who perform endurance events. Vegetarian athletes can meet their protein needs from predominantly or exclusively plant-based sources when a variety of these foods are consumed daily and energy intake is adequate. Muscle creatine stores are lower in vegetarians than non-vegetarians. Creatine supplementation provides ergogenic responses in both vegetarian and non-vegetarian athletes, with limited data supporting greater ergogenic effects on lean body mass accretion and work performance for vegetarians. The potential adverse effect of a vegetarian diet on iron status is based on the bioavailability of iron from plant foods rather than the amount of total iron present in the diet. Vegetarian and non-vegetarian athletes alike must consume sufficient iron to prevent deficiency, which will adversely affect performance. Other nutrients of concern for vegetarian athletes include zinc, vitamin B12 (cyanocobalamin), vitamin D (cholecalciferol) and calcium. The main sources of these nutrients are animal products; however, they can be found in many food sources suitable for vegetarians, including fortified soy milk and whole grain cereals. Vegetarians have higher antioxidant status for vitamin C (ascorbic acid), vitamin E (tocopherol), and beta-carotene than omnivores, which might help reduce exercise-induced oxidative stress. Research is needed comparing antioxidant defences in vegetarian and non-vegetarian athletes.

Antioxidants↗

PubMed2005

Influence of exercise training and age on CD14+ cell-surface expression of toll-like receptor 2 and 4.

The influence of an exercise training program and age on inflammatory cytokine production and CD14+cell-surface expression of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) was examined in 60 younger and older subjects. Subjects were assigned to: young physically active (YPA, n = 15; 25.2 +/- 5.0 years), young physically inactive (YPI, n = 14; 24.9 +/- 4.7 years), older physically active (OPA, n = 14; 71.2 +/- 4.4 years) or older physically inactive (OPI, n = 17; 71.0 +/- 4.3 years) groups. YPI and OPI completed 12 weeks (3 days/week) of endurance (20 min) and resistance exercise (eight exercises, two sets). YPA and OPA groups were instructed to continue their normal activity for 12 weeks. Blood was collected at rest, before and after the 12-week training and control period. A whole blood method was used to determine lipopolysaccharide-(LPS) and peptidoglycan-(PGN) stimulated IL-6, IL-1beta, and TNF-alpha production with supernatants analyzed using ELISA. CD14+ cell-surface expression of TLR2 and TLR4 were measured using flow cytometry. Training increased estimated VO(2max) by 10.4% and increased strength by an average of 38.1%. YPI and OPI had a post-training reduction in LPS-stimulated IL-6 production (P < .01), but LPS-stimulated IL-1beta and TNF-alpha and PGN-stimulated cytokines were not changed. CD14+ cell TLR4 was significantly reduced (P < .05) in YPI and OPI groups after training, but TLR2 was not significantly changed. An exercise training program reduced LPS-stimulated IL-6, concomitant with lower TLR4. These results provide further support for a training- or physical activity-induced lowering of TLR4 and inflammation.

Adolescent↗

PubMed2005

Beef and soy-based food supplements differentially affect serum lipoprotein-lipid profiles because of changes in carbohydrate intake and novel nutrient intake ratios in older men who resistive-train.

OBJECTIVE: We examined if the predominant source of dietary protein influenced the lipoprotein-lipid profile in older men who performed resistive exercise training (RT). DESIGN: This is a 14-week, randomized, repeated-measures study with a 12-week period of RT with supplementation of different sources of dietary protein (beef and soy). SETTING: Nutrition, Metabolism, and Exercise Laboratory, Central Arkansas Veteran's Healthcare System, North Little Rock, Ark. Subjects Twenty-six healthy men were recruited, and 21 men (age 65 +/- 5 years, body mass index 28.2 +/- 2.6 kg/m 2 ) completed the study. Interventions For 14 weeks, all men were counseled to self-select a lacto-ovo-vegetarian diet. For 2 weeks (baseline), all men also consumed 0.6 g-protein/kg per day from portioned quantities of soy-based texturized vegetable protein foods. For the next 12 weeks, 11 men were randomized to continue with texturized vegetable protein foods (VEG group), whereas 10 men were randomized to receive 0.6 g-protein/kg per day from portioned quantities of beef (BEEF group) and continue their otherwise lacto-ovo-vegetarian diet. All men participated in RT 3 d/wk during this 12-week period. Assessments of upper and lower body muscle strength and power, serum lipoprotein-lipid profile, and dietary nutrient intakes were made at baseline and week 12 of RT (POST). RESULTS: The BEEF and VEG groups increased ( P < .05) overall muscle strength and muscle power with RT, with no differences between groups. From baseline to POST, the BEEF group had increased concentrations of high-density lipoprotein cholesterol ( P = .025; HDL-C), low-density lipoprotein cholesterol ( P = .027; LDL-C), and total cholesterol ( P = .015: CHOL), with no changes ( P > .05) in triacylglycerol (TG), the CHOL/HDL-C ratio, or the TG/HDL-C ratio. The VEG group did not experience within-group changes ( P > .05) in any lipoprotein-lipid parameter. At POST, the concentrations of HDL-C, LDL-C, and CHOL were greater in the BEEF group compared with the VEG group. There were significant interaction effects for HDL-C ( P = .004) and the TG/HDL-C ratio ( P = .022). Multiple regression analysis determined that, regardless of intervention, change in the saturated fat/fiber ratio (SF/fiber) predicted CHOL (adjusted R 2 = 0.34); the SF/fiber ratio predicted LDL-C (adjusted R 2 = 0.36); the cholesterol/fiber intake ratio predicted HDL-C (adjusted R 2 = 0.26), and the change in carbohydrate intake predicted the CHOL/HDL-C ratio (adjusted R 2 = 0.37) and TG (adjusted R 2 = 0.44). CONCLUSIONS: These results suggest that the lipoprotein-lipid profile in these older men was differentially affected by supplementation with beef versus soy-based foods during RT. Regardless of group, the lipoprotein-lipid changes were predicted by differences in the SF/fiber ratio and cholesterol/fiber ratio and increases in carbohydrate intake over time.

Aged↗

PubMed2005

Water balance, hydration status, and fat-free mass hydration in younger and older adults.

BACKGROUND: Older adults are at increased risk of dehydration, yet water balance is understudied in this population. OBJECTIVE: This controlled diet study assessed the effect of age on water input, output, and balance in healthy adults. Hydration status (plasma osmolality and urine specific gravity) and body composition were also measured. DESIGN: Eleven men and 14 women aged 23-46 y and 10 men and 11 women aged 63-81 y were subjects. Water balance was assessed during days 7-10 of three 18-d controlled feeding trials with protein intakes of 0.50, 0.75, and 1.00 g . kg(-1) . d(-1). Total water input included water from the provided foods and beverages, ad libitum intake, and metabolic production. Water output included the losses in urine and stool and the insensible losses from respiration and nonsweating perspiration. RESULTS: Ad libitum water consumption, total water intake, water output through urine, total water output, and net water balance were not different in the older subjects than in the younger subjects. Markers of hydration status were within the range of clinical normalcy for all groups. Total body water (TBW) was not significantly different, fat-free mass (FFM) was significantly lower (P < 0.05), and FFM hydration (TBW:FFM) was significantly higher (P < 0.05) in the older subjects than in the younger subjects. Dietary protein intake did not influence any of these results. CONCLUSIONS: These results show that healthy older adults maintain water input, output, and balance comparable to those of younger adults and have no apparent changes in hydration status. The results support that the hydration of FFM is increased in older men and women.

Adult↗

PubMed2004

The Yale Physical Activity Survey for older adults: predictions in the energy expenditure due to physical activity.

OBJECTIVE: To evaluate the accuracy of the Yale Physical Activity Survey (YPAS) for older adults. DESIGN: Fourteen-week strictly controlled diet study. SUBJECTS/SETTING: Eleven men and 17 women, age range 55 to 78 years, spent 10 weeks in an outpatient setting and 4 weeks in an inpatient setting at the General Clinical Research Center, Noll Physiological Research Center, The Pennsylvania State University, University Park. INTERVENTION: Subjects were provided dietary energy to maintain body weight within +/-0.5 kg of baseline weight. The daily menus contained 0.8 g protein per kilogram body weight and nonprotein energy as 60% carbohydrate and 40% fat. MAIN OUTCOME MEASURES: Metabolizable energy intake (MEI) was measured at week 14 from the gross energy contents of food, urine, and feces, with corrections for any body composition changes during the last 6 weeks of weight maintenance. Resting energy expenditure (REE) was determined using indirect calorimetry. The thermic effect of feeding (TEF) was estimated to be 10% of the MEI. The energy expenditure due to physical activity (EEPA) was derived by the formula: EEPA=MEI-REE-TEF. This value was compared with the EEPA estimated from the YPAS. Statistical analyses performed Two-factor analysis of variance with repeated measures and paired t tests. RESULTS: At week 14, after a minimum of 6 weeks of sustained weight stability, the derived EEPA was not different from that estimated using the YPAS for the men and the men and women combined, while the YPAS estimate was more than the measured mean value for the women (P<.05). There was wide variability in the accuracy of the EEPA prediction for individual subjects (range=-637 to 794 kcal). APPLICATIONS/CONCLUSIONS: The YPAS may be used, with caution, to estimate the EEPA for groups of older individuals, and may provide inaccurate estimates of the EEPA in older individuals.

Aged↗

PubMed2004

Pinitol supplementation does not affect insulin-mediated glucose metabolism and muscle insulin receptor content and phosphorylation in older humans.

This study assessed the effect of oral pinitol supplementation on oral and intravenous glucose tolerances and on skeletal muscle insulin receptor content and phosphorylation in older people. Fifteen people (6 men, 9 women; age 66 +/- 8 y; BMI 27.9 +/- 3.3 kg/m(2); hemoglobin A1c 5.39 +/- 0.46%, mean +/- SD) completed a 7-wk protocol. Subjects were randomly assigned to groups that during wk 2-7 consumed twice daily either a non-nutritive beverage (Placebo group, n = 8) or the same beverage with 1000 mg pinitol dissolved into it (Pinitol group, n = 7, total dose = 2000 mg pinitol/d). Testing was done at wk 1 and wk 7. In the Pinitol group with supplementation, 24-h urinary pinitol excretion increased 17-fold. The fasting concentrations of glucose, insulin, and C-peptide, and the 180-min area under the curve for these compounds, in response to oral (75 g) and intravenous (300 mg/kg) glucose tolerance challenges, were unchanged from wk 1 to wk 7 and were not influenced by pinitol. Also, pinitol did not affect indices of hepatic and whole-body insulin sensitivity from the oral glucose tolerance test and indices of insulin sensitivity, acute insulin response to glucose, and glucose effectiveness from the intravenous glucose tolerance test, estimated using minimal modeling. Pinitol did not differentially affect total insulin receptor content and insulin receptor phosphotyrosine 1158 and insulin receptor phosphotyrosine 1162/1163 activation in vastus lateralis samples taken during an oral-glucose-induced hyperglycemic and hyperinsulinemic state. These data suggest that pinitol supplementation does not influence whole-body insulin-mediated glucose metabolism and muscle insulin receptor content and phosphorylation in nondiabetic, older people.

Aged↗

PubMed2004

Short-term low-protein intake does not increase serum parathyroid hormone concentration in humans.

We investigated whether inadequate dietary protein would result in increased serum parathyroid hormone (PTH) concentration, consistent with secondary hyperparathyroidism. Data from 2 controlled feeding studies were utilized. In study 1, 26 healthy women (15 young, 21-46 y, and 11 elderly, 70-81 y) consumed for 12 d each in separate trials 3 levels of protein, 1.00, 0.75, and 0.50 g protein/(kg. d). Blood was drawn from fasting subjects on d 12 of each trial. In study 2, 24 persons (54-80 y) were fed diets with either 1.20 g protein/(kg. d) for 2 wk (HPro, n = 11, 6 men, 5 women) or 1.2 g protein/(kg. d) for 1 wk and then 0.50 g protein/(kg. d) for a 2nd week (IPro, n = 13, 6 men, 7 women). Blood was obtained from fasting subjects after wk 1 and 2. Consistent with altered protein metabolism, urinary total nitrogen excretion and blood urea nitrogen fell progressively with decreasing protein intake in study 1; in study 2, the values decreased from wk 1 to 2 in the IPro group only. Serum intact PTH concentrations did not differ among the 3 protein intakes in study 1, or between the HPro and IPro groups in study 2. These findings do not support the hypothesis that the short-term ingestion of inadequate dietary protein increases serum PTH concentration.

Adult↗

PubMed2004

Resistive training and chromium picolinate: effects on inositols and liver and kidney functions in older adults.

This study assessed the effects of resistive training (RT) with or without chromium picolinate (Cr-pic) supplementation on the 24-h urinary excretions of myo-inositol, D-chiro-inositol, and pinitol, as well as clinical indices of kidney and liver functions. Thirty-two nondiabetic subjects, age 62 +/- 4 y, performed RT twice weekly for 12 wk and consumed either 924 ug Cr/d as Cr-pic (n = 17) or a placebo (n = 15). Whole-body strength increased in all subjects by 20 % and urinary chromium excretion increased 47-fold in the Cr-pic group. Urinary myo-inositol, D-chiro-inositol, and pinitol were not changed with RT or influenced by Cr-pic. Serum indices of kidney and liver functions were within clinically normal ranges at baseline and the end of the study. These results suggest that RT did not influence the urinary excretions of inositols. High dose Cr-pic did not influence the urinary excretion of inositols and the selected indices of kidney and liver functions in conjunction with RT.

Area Under Curve↗

PubMed2004

TLR4 is lower in resistance-trained older women and related to inflammatory cytokines.

INTRODUCTION/PURPOSE: Regular exercise may offset age-associated increases in inflammatory cytokines and reduce the risk of developing diseases with an inflammatory etiology by exerting "anti-inflammatory" effects. Toll-like receptor 4 (TLR4) signaling stimulates inflammatory cytokine production, and may explain the "anti-inflammatory" effect attributed to regular exercise. Therefore, the purpose of the present study was to compare the effect of acute (3 sets, 9 exercises, 10 repetitions at 80% of the 1-repetition maximum) and chronic resistance exercise on TLR4 and inflammatory cytokines. METHODS: Venous blood samples were collected from trained (TR, N = 10) and untrained (UT, N = 10) older (65-80 yr) postmenopausal women: before (PRE), immediately post (POST), and 2 h (2H), 6 h (6H), and 24 h (24H) after completion of exercise. Cell-surface expression of TLR4 (two-color immunofluorescent cytometry), LPS (25 microg x mL(-1))-stimulated cytokine production (ELISA), plasma cytokines (ELISA), and mRNA expression of TLR4 and cytokines (RT-PCR) were determined for each sample. RESULTS: TR had 124% less cell-surface TLR4 expression than UT (P < 0.05). A significant time effect was found for LPS-stimulated IL-6, IL-1beta, and TNF-alpha, where 6H was significantly greater than all other samples. No significant effects were found for plasma (IL-6 and TNF-alpha) or mRNA expression (IL-6, TNF-alpha, and IL-1beta) of inflammatory cytokines. When subjects were grouped according to cell-surface TLR4 expression (HI and LO), LPS-stimulated TNF-alpha (302%), IL-1beta (209%), and IL-6 (167%) production was greater for HI than LO (P < 0.05). CONCLUSION: Regularly exercising older women expressed less cell-surface TLR4 but did not have lower plasma levels or produce less LPS-stimulated inflammatory cytokines at rest or in response to a single bout of resistance exercise. TLR4 changes may explain the "anti-inflammatory" effect that has recently been attributed to chronic (2x wk for previous 24 months) resistance exercise training.

Adaptation, Physiological↗

PubMed2003

Comparisons of vegetarian and beef-containing diets on hematological indexes and iron stores during a period of resistive training in older men.

OBJECTIVE: To test the hypothesis that older men who consumed a vegetarian (lacto-ovo) diet would develop a lower iron status compared with older men who consumed a beef-containing diet during a period of resistive training (RT). DESIGN: Experimental, repeated measures study. SUBJECTS: Twenty-one healthy men aged 59 to 78 years, with a BMI range of 24 to 33 kg/m(2), completed the study. INTERVENTION: All men consumed a vegetarian diet for 2 weeks (baseline). After this, the men were randomly assigned to one of two dietary groups. Eleven men consumed a beef-containing diet, and 10 men continued to consume a vegetarian diet for 12 weeks. During this time all subjects participated in RT three days per week, designated as RT1 to RT12. MAIN OUTCOME MEASURES: Serum ferritin and serum iron concentrations, transferrin saturation, transferrin receptor, total iron binding capacity, and selected hematological variables, as well as selected nutrient intakes and estimated iron bioavailability from three-day diet records, were determined at baseline, RT5, and RT12. STATISTICAL ANALYSES: A general linear model repeated-measures ANOVA was used to examine the effects of group, time, and group x time interactions for iron status and dietary data. RESULTS: Total iron intake was not different between the two groups; however, the beef group had a three to four times greater intake of bioavailable iron (P<.01) than the vegetarian group. Serum iron, total iron binding capacity, transferrin saturation, and transferrin receptor were not significantly different between the beef and vegetarian groups, or changed over time with RT. Serum ferritin decreased over time in both the beef and vegetarian groups during RT (P<.01). Re-introduction of beef into the diets of the beef group increased hemoglobin concentration and hematocrit compared with the vegetarian group during the 12 weeks of RT (group x time, P<.05). These changes were within clinically normal limits. APPLICATIONS/CONCLUSIONS: Older men who consume a beef-containing, higher-bioavailable-iron diet, compared with a vegetarian, lower-bioavailable-iron diet, have an increased hematological profile during a 12-week period of RT. Older men who consume either a beef-containing or a vegetarian diet maintain a hematological profile within clinically normal limits during 12 weeks of RT.

Aged↗

PubMed2003

The Atwater energy equivalents overestimate metabolizable energy intake in older humans: results from a 96-day strictly controlled feeding study.

The Atwater energy equivalents of 16.7, 16.7 and 37.7 kJ/g of protein, carbohydrate and fat, respectively, are the standard values used to calculate the macronutrient intakes required to meet a person's metabolizable energy requirement. The aim of this study was to compare in older people the measured metabolizable energy intake (MEI(MEAS)) required to achieve and maintain stable body weights with the MEI estimated using the Atwater energy equivalents (MEI(AT)). During a 96-d (14-wk) strictly controlled dietary period, 11 men and 17 women (55-78 y old) were each provided a MEI(AT) to maintain body weight within +/- 0.5 kg of baseline weight. The MEI(MEAS) was determined retrospectively from the gross energy contents of food, urine and feces samples collected during week 14. Resting energy expenditure was measured using indirect calorimetry. At wk 14, MEI(AT) overestimated MEI(MEAS) by 26%. These results suggest that the Atwater energy equivalent values may overestimate the actual MEI of older people.

Aged↗

PubMed2002

Dietary protein adequacy and lower body versus whole body resistive training in older humans.

This study assessed the effects of long-term consumption of the United States Recommended Dietary Allowance (RDA) for protein by older people who were sedentary or performed resistive training (RT) on body composition, skeletal muscle size and protein metabolism, and if the number of muscle groups trained influenced the muscle hypertrophy response to RT. Twelve men and 17 women (age range 54-78 years) completed this 14 week controlled diet and exercise study. Throughout the study, each subject completely consumed daily euenergetic menus that provided the RDA of 0.8 g protein kg(-1) day(-1). From study weeks 3-14 (weeks RT1-RT12), 10 subjects (four men, six women) performed whole body RT (WBRT), nine subjects (four men, five women) performed lower body RT (LBRT) and 10 subjects (four men, six women) remained sedentary (SED). Both the LBRT and WBRT groups performed knee extension and flexion exercises, and the WBRT group also performed chest press and arm pull exercises (three sets per exercise at 80 % of one repetition maximum, 3 days per week for 12 weeks). From week 2 (baseline) to week RT12, muscle strength increased in muscle groups trained in the LBRT and WBRT groups, and was not changed in the SED group. From baseline to week RT12, whole body muscle mass and protein-mineral mass were not changed, fat-free mass (P = 0.004) and total body water (P = 0.013) were decreased, and percentage body fat was increased (P = 0.011) in these weight-stable older people, independent of group assignment. The RT-induced increases in mid-thigh muscle area (from computed tomography scans) were comparable in the LBRT and WBRT groups (2.13 +/- 1.26 cm(2) and 2.17 +/- 1.24 cm(2), respectively), and were different from those in the SED group, which lost muscle area (-1.74 +/- 0.57 cm(2); group-by-time P < 0.05). From baseline to week RT12, 24 h urinary total nitrogen excretion decreased (P < 0.001), nitrogen balance shifted from near equilibrium to positive, whole body leucine oxidation (from the infusion of L-[(13)C]leucine) decreased (P < 0.05) and net (postabsorptive vs. postprandial) leucine balance (P < 0.05) increased from near equilibrium to positive, with no differences in responses over time among the three groups. In conclusion, the number of muscle groups trained did not influence whole body protein metabolism or RT-induced muscle hypertrophy in older people. Most of these data are consistent with a successful adaptation to the RDA for protein. However, research should continue to question whether the decreases in fat-free mass and total body water observed in all subjects, and the decrease in mid-thigh muscle area in the SED group, are physiological accommodations, and whether the RDA for protein might be marginally inadequate for older people to maintain skeletal muscle.

Aged↗

PubMed2002

Lower body versus whole body resistive exercise training and energy requirements of older men and women.

A person's energy requirement is defined as the metabolizable energy intake (MEI) consumed over a period of body weight stability. Controversy exists regarding whether resistive exercise training (RT) influences the energy requirement of older people. The aim of this study was to assess the effect of RT on the energy requirement of older people. The subjects were 11 men (M) and 17 women (W); age range, 55 to 78 years. During a 14-week precisely controlled diet study, each subject consumed foods and beverages portioned to provide sufficient MEI to match their energy requirement and to keep body weight stable at +/- 0.5 kg of their starting weight. MEI was determined from bomb calorimeter analyses of the gross energy (GE) content of food, urine, and feces samples collected during 4-day intake-balance periods at study weeks 2, 8, and 14 (baseline, week RT6, and week RT12, respectively). MEI = GE(food)-GE(urine) - GE(feces). Resting energy expenditure (REE) was measured using an indirect calorimeter. From study weeks 3 to 14, 10 subjects (4 M, 6 W) remained sedentary (SED), 9 subjects (4 M, 5 W) performed lower body RT (LBRT) 3 times/week, and 9 subjects (3 M, 6 W) performed whole body RT (WBRT) 3 times/week. Body weight was not different among the SED, LBRT, and WBRT groups at baseline and were not changed over time or influenced by RT. At baseline, MEI was not different among the 3 groups. From weeks RT1 to RT12, MEI had to be increased by 17% +/- 5% (mean +/- SEM), 14% +/- 7%, and 12% +/- 7% in the SED, LBRT, and WBRT groups, respectively, to maintain stable body weights. At week RT12, the MEI required to maintain stable body weight was not significantly different among the SED, LBRT, and WBRT groups (9.45 +/- 0.95, 9.40 +/- 0.83, and 8.64 +/-0.53 MJ/d, respectively). At week RT12, the MEI and MEI/REE ratio were higher in men versus women, independent of group assignment. These data suggest that RT, whether performed using the lower body only or the whole body, does not increase the energy requirement of older people. Also, these data show that the energy requirement of older men is greater than that of older women.

Age Factors↗

PubMed2002

Effect of protein source on resistive-training-induced changes in body composition and muscle size in older men.

BACKGROUND: Aging is associated with reductions in muscle mass and strength, but nutrition and exercise interventions can delay this progression and enhance the quality of life. OBJECTIVE: We examined whether the predominant source of protein consumed by older men influenced measures of muscle size and strength, body composition, resting energy expenditure, and skeletal muscle creatine concentrations in response to 12 wk of resistive training. DESIGN: After consuming a lactoovovegetarian (LOV) diet for 2 wk, 21 men aged 65 +/- 5 y were randomly assigned to either consume a beef-containing (BC) diet (n = 10) or to continue the LOV diet (n = 11) throughout resistive training. The BC diet included 0.6 g protein. kg(-1). d(-1) from beef and the LOV diet included 0.6 g protein. kg(-1). d(-1) from textured vegetable protein (soy) sources. The remaining protein in the diets came from self-selected LOV sources. RESULTS: The mean total protein intake for both groups ranged from 1.03 to 1.17 g. kg(-1). d(-1) during the intervention. Men in both groups had improvements (14-38%) in maximal dynamic strength of all the muscle groups trained with no significant difference between groups. With resistive training, cross-sectional muscle area of the vastus lateralis increased in both groups (4.2 +/- 3.0% and 6.0 +/- 2.6% for the LOV and BC groups, respectively) with no significant difference between groups. Body composition, resting energy expenditure, and concentrations of muscle creatine, phosphocreatine, and total creatine did not differ significantly between groups or change over time. CONCLUSIONS: These data suggest that increases in muscle strength and size were not influenced by the predominant source of protein consumed by older men with adequate total protein intake.

Aged↗

PubMed2002

Effects of resistive training and chromium picolinate on body composition and skeletal muscle size in older women.

This study assessed the effect of resistive training (RT), with or without highdose chromium picolinate (Cr-pic) supplementation, on body composition and skeletal muscle size of older women. Seventeen sedentary women, age range 54-71 years, BMI 28.8 +/- 2.4 kg/m2, were randomly assigned (double-blind) to groups (Cr-pic, n = 9; Placebo, n = 8) that consumed either 924 micrograms Cr/d as Cr-pic or a low-Cr placebo (< 0.2 microgram Cr/d) during a 12-week RT program (2 day/week, 3 sets.exercise-1.d-1, 80% of 1 repetition maximum). Urinary chromium excretion was 60-fold higher in the Cr-pic group, compared to the Placebo group (p < .001), during the intervention. Resistive training increased maximal strength of the muscle groups trained by 8 to 34% (p < .001), and these responses were not influenced by Cr-pic supplementation. Percent body fat and fat-free mass were unchanged with RT in these weight-stable women, independent of Cr-pic supplementation. Type I and type II muscle fiber areas of the m. vastus lateralis were not changed over time and were not influenced by Cr-pic supplementation. These data demonstrate that high-dose Cr-pic supplementation did not increase maximal strength above that of resistive training alone in older women. Further, these data show that, under these experimental conditions, whole body composition and skeletal muscle size were not significantly changed due to resistive training and were not influenced by supplemental chromium picolinate.

Aged↗