Browsing by Author "Rankin, Janet L. Walberg"
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- Acid-base regulation during exercise in the horseFerrante, Pamela L. (Virginia Tech, 1994-01-15)Effects of fat adaptation and NaHC0₃ supplementation on acid-base homeostasis were quantitated during repeated sprint exercise in horses. Contribution of strong ions ([SID]), Pco₂, and weak electrolytes ([Atot]) to changes in plasma [H⁺] and the role of erythrocytes in acid-base balance were examined at rest and during exercise. Effects on plasma glucose and blood lactate [Lac⁻] concentrations due to sample handling were also assessed. During exercise, blood [Lac⁻] was higher when horses received NaHC0₃ compared to water prior to exercise (P=0.0024), and in fat adapted horses compared to horses fed a control diet (P=0.0240). Blood [Lac-] was higher in fat adapted horses given NaHC0₃ compared to other diet/treatment combinations (P=0.0276). Plasma [SID] was higher during exercise when horses were given NaHC0₃ compared to plain water (P=0.0054), which contributed to decreasing [H⁺] and increasing [HC0₃⁻] during exercise (P=0.0001). Plasma Pco₂ contributed less to increasing plasma [H⁺] during exercise in fat-adapted horses compared to horses fed the control diet (P=0.0282). Intraerythrocyte [SID] decreased (P=0.0160) and [Atod increased (P=0.0002) which contributed to increasing [H⁺] within the cell (P=0.0228).
- Aerobic exercise training for patients suffering from intermittent claudicationBostian, Allen M. (Virginia Tech, 1986-04-05)Nine patients with intermittent claudication diagnosed at least 6 months before this investigation were evaluated to determine the effects of walking exercise on serum lactate accumulation (HLa, mmol⁻¹), ankle pressure index (API), total treadmill time (sec), and onset of leg pain (sec) in the most severely diseased limb. Subjects were evaluated via a functional walking tolerance test before participation in a thrice-weekly exercise program lasting 6 weeks. Post- treatment, the participants were re-evaluated on an identical walking test. Measurements of HLa accumulation and API were taken at rest and immediately following termination of the treadmill test. In the training sessions, body weight (kg), exercise heart rate (HR), systolic blood pressure (SBP), and distance traveled (m) were recorded daily. There were no significant changes (p<.05) after training in total time (mean increase = 23.7%) or time for onset of pain in the treadmill test (mean increase = 30.1%). Neither were there significant changes (p<.05) in API or HLa levels taken immediately after exercise, when pre- and post-training treadmill test data were compared. The weekly responses for exercise HR, and SBP, as well as body weight remained stable throughout. Mean distance walked by the subjects increased 203% (± 45%) across the 6 weeks. These data suggest that increases in total distance walked in an exercise program were apparently not related to HLa accumulation or API measurements in the working muscles, and that other mechanisms must be investigated in future studies to explain enhanced performance of such subjects.
- Aging, Physical Activity, and Energy Intake RegulationVan Walleghen, Emily Lynn (Virginia Tech, 2006-07-31)More than seventy percent of Americans over the age of sixty are classified as overweight or obese, and the future incidence of these conditions is expected to rise. Although it is unclear why older adults are predisposed to weight gain, decreased total energy expenditure may contribute to positive energy balance. It is also possible that age-related impairments in energy intake regulation result in the inability to appropriately adjust food intake to meet energy requirements with advancing age. The purpose of these investigations was to determine the influence of age and habitual physical activity on acute regulation of energy intake. Secondary objectives were to determine if there are sex differences in energy intake regulation, and to determine if pre-meal water consumption decreases meal energy intake in young and older adults. To achieve these objectives, the ability to spontaneously adjust energy intake at a meal under "preloading" conditions in which a yogurt shake or water was consumed prior to the meal was determined. We hypothesized that older adults would demonstrate less accurate energy intake regulation than younger adults, but that energy intake dysregulation would be attenuated in physically active older adults. We also expected that young men would have higher accuracy of energy intake regulation compared to young women matched for dietary cognitive restraint and cardiorespiratory fitness, and that pre-meal water consumption would decrease meal energy intake in young and older adults. Our main finding was that energy intake regulation is significantly impaired in older compared to younger adults, and that habitual physical activity improves short-term, but not acute, energy intake regulation. We also found that young men demonstrate significantly higher accuracy of energy intake regulation compared to young women. Lastly, we determined that pre-meal water consumption significantly decreases meal energy intake in older, but not young, adults. Overall, these results indicate that acute energy intake regulation is less accurate with advancing age, but that regular physical activity improves short-term energy intake regulation. Additionally, sex appears to influence energy intake regulation, and water consumption is a potential strategy to reduce energy intake in older adults.
- Assessing Barriers and Motivators for Use of a Trail for Active Transportation in a College TownFitzPatrick, Timothy Michael (Virginia Tech, 2017-05-30)A high amount of the US population is not physically active, contributing to rates of heart disease and obesity. One strategy to increase physical activity is to use more active transportation, defined as walking or biking for transit. Besides increasing physical activity levels, active transportation can provide other benefits such as decreased air pollution from cars. College campuses provide opportunities for active transportation as most residences are close to campus. Therefore, we examined reasons for use and barriers to active transportation in students living in a community connected to a large university via a 1.9 mile, paved protected trail. Two pedestrian and bicycle counters were placed to find the number of walkers and bikers on the trail per day and students were recruited to take an online survey. We found that more people used the trail during the weekday compared to the weekend. Students did not receive much support from their friends and family to use the trail. Users of the trail were more likely to believe that using active transportation helps protect the environment while non-users were uncomfortable using a bike. Barriers included the time it took to use the trail and the need to carry items. Both users and non-users indicated that a financial incentive would motivate them to use the trail more. We conclude that non-users may be uncomfortable using a bike and worry about carrying their items for class. Changing university parking fees, providing bike lessons, and placing signs with directions and time to campus may increase active transportation to the university via this trail.
- Carbohydrate Supplementation and Resistance Exercise Performance in Males Undergoing Energy RestrictionDalton, Renee A. III (Virginia Tech, 1997-07-25)This study examined the effects of carbohydrate supplementation on resistance exercise performance, cortisol levels, and creatine kinase levels in trained males undergoing energy restriction. Sixteen experimental subjects were randomly assigned to a carbohydrate (C, n=8) or placebo group (P, n=8). The remaining six subjects served as controls (N). Performance tests were done before (Trials 1 and 2) and after (Trial 3) energy restriction. Experimental subjects consumed a low calorie formula diet for three days (18 kcal-1 kg-1 d-1). They had blood drawn before and after T2 and T3. For T3, they consumed either a carbohydrate (1g kg-1) or a placebo beverage 30 minutes before exercise. There was a significant increase in resting cortisol levels following energy restriction. CK levels were significantly elevated after exercise, suggestion muscle damage. Carbohydrate supplementation had no effect on blood glucose, cortisol, creatine kinase, or RPE. The number of repetitions performed during the final set of bench press showed significant interaction between groups and time. P and N increased the number of repetitions performed from T2 to T3 (15.0 + 1.4 to 17.3 + 0.8 for P, 15.0 + 2.7 to 16.7 + 2.3 for N). C decreased the number of repetitions performed 17.6 + 0.7 to 17.3 + 1.0). The number of repetitions performed during the final set of leg extensions showed no interaction between groups and time (p=0.801). This study did not support a benefit of consuming carbohydrate prior to resistance exercise for dieting athletes but illustrates that energy restriction increases a catabolic hormone.
- Contractile Performance and Energy Utilization of Skeletal Muscle; Creatine Kinase and Acto-myosin ATPaseMelnyk, Jason Alexander (Virginia Tech, 2009-01-23)Creatine kinase (CK) primarily serves as an energy buffer assisting in regulating ATP homeostasis through synthesis of ATP from ADP and phosphocreatine (PCr). This enzyme is bound in the sarcomere near sites of ATP consumption via acto-myosin ATPase (A‧M‧ATPase) and research in cardiac muscle has found that PCr can alter contractile performance (maximal isometric force and Ca²⁺ sensitivity). Based on this evidence, CK and A‧M‧ATPase may be coupled in skeletal muscle. Therefore the purpose of this investigation was to determine the influence of the CK system on contractile performance and energy utilization in skeletal muscle. When skinned fibers (membrane removed) were provided a limited supply of [ATP] (0.1 mM), this resulted in increased Ca²⁺ sensitivity. The addition of PCr to low ATP solutions restored Ca²⁺ sensitivity and allowed normal isometric force generation across a range of [Ca²⁺] via ATP synthesis by CK. This was also possible with only CK reaction substrates (ADP, PCr) in the absence of ATP. Based on these findings, endogenous CK activity in glycerol skinned skeletal muscle fibers is sufficient to permit normal function of the contractile apparatus. Energy utilization was studied by indirect assessment of ADP production. Decreased net ADP production as measured by NADH fluorescence revealed endogenous CK was able to convert ADP produced by A‧M‧ATPase to ATP in skeletal muscle across a range of both [Ca²⁺] and [ATP]. This was confirmed directly via high-performance liquid chromatography measurements of ATP and ADP by showing that skinned skeletal muscle bundles have sufficient endogenous CK activity to produce ATP from substrates (ADP, PCr) and the ability to maintain low [ADP] in the presence of PCr. This study adds to the evidence for specific compartmentation of CK near sites of ATP utilization and contributes to the body of knowledge on contractile performance in skinned skeletal muscle fibers. By showing how changing demands on skeletal muscle (through increased Ca²⁺) alters force production and Ca²⁺ sensitivity, these findings lend support for the importance of endogenous CK as a pathway of ATP regeneration in skeletal muscle.
- Diet, body weight patterns and menstrual status of competitive female body buildersEdmunds, Cynthia Ekstein (Virginia Tech, 1990-09-15)The purpose of the study was to provide descriptive information on nutritional profiles and body weight (BW) patterns of 6 competitive female body builders (x age = 27) before, during and after a competition. Precompetition (-28 to -26 d); (-9 to -7 d), competition (-2 to 0 d) and post competition (+1 to +3 d); (+26 to +28 d) 3-d diet and BW records were recorded. Diet records were analyzed using the Nutripractor 6000 nutrient analysis system. Two weeks precompetition, percent body fat was estimated using skinfold measurements. All subjects completed a 60-item fixed choice and open-ended questionnaire concerning menstrual characteristics, training and dietary practices. A subgroup (n=2) agreed to collect daily urine samples for one month prior and one month after competition. Samples were analyzed for estradiol (E2) and progesterone (P4).
- Dietary Intake and Bone Mineral Density in Young-Adult FemalesBeiseigel, Jeannemarie Mary (Virginia Tech, 2000-07-21)The late second and early third decades of life are critical periods for bone health due to the attainment of peak bone mass during this time, yet little is known about relationships between lifestyle factors and bone health among young-adult females. Therefore, anthropometric, body composition, and nutritional variables were examined in relation to bone mineral density (BMD) and biochemical markers of bone turnover in a group of 60 healthy, young-adult females aged 18 to 25 years. Body weight, body mass index (BMI), fat-free soft tissue mass (FFST), and fat mass had statistically significant and positive associations with BMD. Mean daily dietary protein, magnesium, and iron intakes had statistically significant and negative associations with BMD. A second study compared dietary intake, BMD, and biochemical markers of bone turnover in young-adult females with chronic dieting habits to nondieters. Anthropometric and body composition variables between chronic dieters and nondieters were not statistically different; however, chronic dieters had statistically significantly lower average daily dietary intakes of energy, macronutrients, and selected micronutrients compared to nondieters. Chronic dieters had statistically significantly higher whole body (WB) BMD compared to nondieters. Moderate effects were observed for WB, lumbar spine, trochanter, and total proximal femur BMD such that chronic dieters possessed greater BMD compared to nondieters. It appears that among young-adult females, total body weight, particularly FFST mass, has an important association with BMD. Although nutritional inadequacies among young-adult females raise concerns, overconsumption of nutrients may increase the likelihood of nutrient-nutrient interactions that may have a less than optimal impact on BMD. Future investigations of dietary intake and BMD among young-adult females are warranted.
- The effect of boron supplementation on bone mineral density and hormonal status in college female athletesVolpe, Stella L. (Virginia Tech, 1991)Twenty-eight college female volunteers, 18 to 24 years of age, were studied to determine their bone mineral density and hormonal status following 10 months of supplementation with boron. Seventeen of the subjects were college athletes (A) who participated in either varsity basketball, tennis, track, triathlons, or volleyball. Eleven eumenorrheic subjects were placed in the sedentary group (S). All athletes were eumenorrheic, except for two, who were amenorrheic. The subjects were randomly assigned to either a placebo (cornstarch) or 3 mg of Tri-Boron (TWin Labs, Ronkonkoma, NY) per day. The study was single blind; the placebo and boron supplements were identical in appearance. The subjects' maximal oxygen consumption (V02max ) was assessed at month 0 only, in order to compare the athletes' aerobic capacity to that of the sedentary group. Subjects were measured at time 0 and 10 months for the following: average daily food intake, bone mineral density, plasma 1,2 5-dihydroxyvi tamin D3 , and plasma alkaline phosphatase. The following parameters were determined at 0, 6, and 10 months: serum 17-Beta estradiol progesterone, and testosterone, and percent body fat, and body weight. The athletes had a significantly greater V02MX (p < 0.05) than the sedentary group. There were no differences between the A and the S groups' food intake as measured in kcals, protein, fat, carbohydrate and fiber content. Although average body weight did not differ between activity groups, the athletes had a significantly lower (p < 0.05) percent body fat than the sedentary group. The athletes showed a slight increase in bone mineral density, whereas the sedentary group showed a slight decrease. The difference between these changes was significant (p < 0.05) between the activity groups. Furthermore, the athletes showed a slight increase in plasma 1,25-dihydroxyvitamin D3 , while the sedentary group showed a decrease in this measure; the difference between these changes also proved to be significant (p < 0.05) between activity groups. There were no significant differences in plasma alkaline phosphatase values. Serum 17-B estradiol and testosterone values exhibited a significant (p < 0.05) increase for all groups combined at 6 months. There were no significant changes observed in serum progesterone. Although significant changes were observed in some of the variables measured, none of the changes were a result of the boron supplementation.
- Effect of Capsaicin Supplementation on Performance of and Physiological Response to Repeated SprintingOpheim, Maximilian Nicholas (Virginia Tech, 2010-02-02)Aim: Fatigue during team sports requiring multiple sprints can result from the combined effects of metabolic, mechanical, neurological, and immune factors. The purpose of this study was to investigate the influence of capsaicin on performance of and the physiological response to an exercise test simulating the fitness demands of team sport game conditions. Methods: This study was a placebo-controlled, crossover design. Nineteen healthy male experienced athletes age 18-30 yr consumed either 3 g/d cayenne (25.8 mg/d capsaicin) or placebo for 1 wk. Directly following the supplementation period, they completed a repeated sprint test consisting of 15 30 m maximal effort sprints on 35 s intervals. Sprint times were recorded via electronic dual-beam timing system. Fasted blood draws for interleukin-6 (IL-6) were taken at baseline prior to supplementation, 45-min pretest, and immediately post test. Heart rate (HR), blood pressure (BP), rate of perceived exertion (RPE), muscle soreness (MS), and gastrointestinal distress (GD) were measured 1-min pretest, during, posttest, and 1-min posttest. MS was also measured for 3 d posttest. Results: Relative to the placebo, capsaicin significantly reduced maximum HR by 9.3%, total average HR by 8.5%, and sprinting average HR by 6.0% (P<0.05). Capsaicin caused GD of at least 2/5 in 24.5% of subjects. There was no difference between treatments in fastest or mean sprint time, fatigue, percent change or difference in IL-6, BP, RPE, sprint or posttest MS. Conclusion: Capsaicin did not influence repeated sprint performance or the inflammatory response, but reduced HR during intense activity and causes substantial GD.
- Effect of Carbohydrate-Protein Beverage on Glycogen Resynthesis and Muscle Damage Induced By Eccentric Resistance ExerciseWojcik, Janet Regina (Virginia Tech, 1998-04-17)This study examined effects of carbohydrate (C), carbohydrate-protein (CP), or placebo (P) beverages following eccentric resistance exercise on muscle damage by serum creatine kinase (CK), muscle protein breakdown by urinary 3-methylhistidine (3MH), muscle soreness, isokinetic muscle strength, muscle glycogen resynthesis, and serum hormones. Untrained males (N=26) underwent a 9-day controlled meat-free diet and 24 hr urine collections. To reduce glycogen, subjects cycled for 40 min at 70% of VO2peak followed by 5 cycling sprints on day 4 evening. On day 5, fasted subjects performed 100 eccentric leg flexions at 120% of 1-RM and drank C (n=8, 1.25 g C/kg), CP (n=9, 0.875 g C/kg, 0.375 g protein/kg), or P (n=9) beverages immediate post-exercise (IPE) and 2 hr later. Muscle biopsies were taken IPE on day 5, and days 6 and 8 mornings. Blood was obtained days 4-10 fasted plus IPE, 3 hr, and 6 hr post-exercise on day 5. At 3 hr on day 5, insulin was higher for CP (24.6 ( 15.5 µIU/ml) and C (17.2 +/- 10.9 µIU/ml) than P (5.3 +/- 0.4 µIU/ml, p<.05). Glycogen was low on day 5, partially recovered on day 6, and normal by day 8 (p<.01) with no difference among groups. Isokinetic quadriceps peak torque at 60o/s decreased 24% on day 6 and remained depressed by 21% on d 8 (p<.01) for all groups. Soreness peaked on day 7 and CK on day 8 (p<.01) with no differences by group. CK increased (p<.01) over day 5 (delta CP 24.6 +/- 19.1, delta P 39.2 +/- 71.6, delta C 70.8 +/- 60.4 U/L) and was highest for C (p<.05). On day 5, CP had lowest 3MH (193.0 +/- 13.8 µmol/d) versus C (251.1 +/- 22.5 µmol/d, p<.05). Testosterone at 3 hr on day 5 was lower for C (4.2 +/- 0.3 ng/ml) and CP (4.3 +/- 0.3 ng/ml) versus P (5.1 +/- 0.2 ng/ml, p<.05). In summary, glycogen, muscle strength and soreness were unaffected by beverage. However, a CP beverage may be beneficial for reducing muscle damage and protein breakdown on the day of eccentric resistance exercise.
- The Effect of Creatine Supplementation on Muscle Fuel Stores, Body Composition, and Exercise Performance During Energy RestrictionRockwell, John A. (Virginia Tech, 1998-11-09)The purpose of this investigation was to determine the effects of a four day creatine load and simultaneous energy restriction on muscle creatine content, exercise performance, and body composition in 24 male recreational resistance trainers, age 18-26. Sixteen subjects were randomly divided into placebo (Pl, n=8) and creatine supplement (CrS, n=8) groups. Control (C, n=8) subjects of the same age were recruited separately g à d-1 to complete the performance and body composition tests while consuming their normal diet. The CrS group was administered 20 g à d-1 of creatine monohydrate (Cr) mixed with 5 g à d-1 of sucrose, while the Pl group was administered 25 of sucrose. Both CrS and Pl consumed a formula diet of 75.3 kJ (18 kcal) à kg-1 à d-1 for 4 d. Testing before and after energy restriction consisted of a repeated sprint cycle performance test (10 sprints of 6s, with 30s rest), hydrostatic weighing, and resting needle muscle biopsy. Testing revealed that subjects in CrS and Pl demonstrated significant decreases in body weight and % body fat (%BF) with no difference between groups. However, Pl demonstrated a significantly greater % loss in FFM (2.4 ± 0.25%) compared to CrS (1.4 ± 0.4%) (p<0.05). The muscle fuel stores of CrS and Pl responded significantly to the diet. Significant increases in muscle total Cr (p<0.01), free Cr (p<0.01), and CrP (p<0.05) of 16.5%, 16.8%, and 16% respectively were demonstrated by CrS over the energy restriction period, while Pl demonstrated significant decreases of 7.2% and 8.2% respectively in muscle total Cr (p<0.01) and free Cr (p<0.05). There were no significant differences between groups for performance during the cycle test, however, there were trends toward group by time interactions for performance enhancement in CrS relative to Pl, as total work (p=0.078) and work capacity (p=0.058) increased 3.8 ± 2.2% in CrS and decreased 0.5 ± 0.4% in Pl. It was concluded that short-term energy restriction resulted in decreased muscle Cr storage, and that Cr supplementation during energy restriction increased muscle Cr and CrP stores. Consumption of Cr allowed CrS to lose a significantly lower % FFM compared to Pl. Cr supplementation resulted in trends toward improved performance in CrS relative to Pl after energy restriction, but did not influence losses in body weight or %BF.
- Effect of DHA supplementation on muscle damage and inflammation during the first two weeks of a novice resistance training programDrager, Christopher John (Virginia Tech, 2013-01-17)Aim: The purpose of this study was to investigate docosahexaenoic acid (DHA) ingestion on muscle damage and inflammation during the first two weeks of a novice resistance training (RT) program. Methods: This study was a placebo-controlled, double-blind design. Forty-one healthy untrained males between the ages of 18 and 28 years consumed 2,000 mg/d of either DHA or corn oil (PCB) for 44 days including a 28 day loading period. Serum fatty acids were analyzed to determine treatment efficacy. During the 17 day training period, an acute eccentric exercise bout was implemented followed by a full-body RT regimen thrice weekly. Six fasted blood draws (days 1, 2, 4, 7, 12, and 17) during this exercise period were analyzed for creatine kinase (CK) and C-reactive protein (CRP). Maximum isometric strength (ISO) of the elbow flexors, delayed onset muscle soreness (DOMS), and range of motion (ROM) were measured on day 1 prior to exercise and also on days 2, 3, 4, 7, 12, and 17. Results: The CK response and the area under the curve (AUC) analysis for DOMS trended to decrease in the DHA group in comparison to placebo (p=0.0925 and p=0.0536, respectively). Treatment showed no effect on CRP levels. DHA supplementation significantly increased serum DHA by 380% as a proportion of total fatty acids (p<0.0001). Conclusion: This study does not demonstrate convincing benefits of DHA ingestion to recovery from a new resistance exercise program but does suggest a need for further investigation.
- The effect of milk consumption immediately following resistance exercise on protein degradation in untrained males before and after a 10-week resistance training protocolPuglisi, Michael Joseph (Virginia Tech, 2002-05-02)This study determined the effect of milk or carbohydrate-electrolyte supplementation immediately after resistance exercise on muscle protein breakdown before and after a 10-week resistance training program. Nineteen untrained males, 18-25 years of age, consumed either a carbohydrate-electrolyte (CHO) or milk (MILK) beverage immediately after a strenuous leg resistance exercise bout, both before and after training. Muscle protein breakdown, as estimated by 3-methylhistidine-to-creatinine ratio, was significantly reduced after resistance exercise for both groups, as the ratio was decreased by 19.9% from baseline on the day of resistance exercise. A trend was present for a training effect for 3-methylhistidine-to-creatinine ratio (p<0.07), as the reduction from before to after resistance exercise was greater after training. There was no difference in muscle protein breakdown between the groups. One hour after exercise, serum concentrations of amino acids were significantly elevated for MILK and significantly reduced for CHO. Serum glucose was significantly higher for both groups 30 minutes post-exercise than baseline, and serum insulin was greater than baseline 30 minutes and 1 hour after exercise. Serum insulin was significantly greater for CHO than MILK 1 hour after resistance exercise. No effect of training was observed for the response of serum amino acids, glucose, or insulin to resistance exercise with beverage ingestion. In conclusion, although the type of beverage ingested post-exercise affected serum insulin and amino acid concentrations, it did not influence the reduction in muscle protein breakdown observed after resistance exercise. A trend was present for a greater reduction in protein breakdown after training.
- Effect of NaHCO₃ and NaCl on high-intensity performance and acid-base balanceAschenbach, William G. (Virginia Tech, 1995-04-06)Although previous investigations have reported performance benefits following the administration of sodium bicarbonate, evidence of its influence on upper-body activity is limited.
- The Effect of Post Exercise Nutrition on Anabolic Response to Resistance ExerciseBird, Randy Lee (Virginia Tech, 2005-03-25)Purpose: To determine the effect of four postexercise beverages, differing in macronutrient content, on metabolic response to an acute resistance exercise bout. Methods: Forty male subjects performed five sets of eight repetitions at 80% 1RM for leg press and leg extension, and then consumed one of four postexercise beverages (Placebo, PL: a carbohydrate-electrolyte beverage, CE; or one of two milk-based beverages, MILK 1: 1% chocolate milk; MILK 2: a high protein milk beverage). Indicators of muscle protein synthesis (MPS) were assessed before and 1-hr after consuming a postexercise beverage. Muscle protein degradation (MPD) was examined the day before and the day of exercise. Results: No significant differences were found among groups in MPS. The resistance exercise bout increased the amount of eIF4E-eIF4G by 4.5% 1-hr postexercise (p<0.05) without affecting the amount of eIF4E-4E-BP1. One hour after beverage consumption, serum total amino acid concentration increased for MILK 1 (p=0.003) and MILK 2 (p<0.001) but decreased for CE (p=0.028) and PL (p=0.276). Consumption of MILK 1, MILK 2, and CE significantly increased circulating levels of serum insulin (p<0.001). Serum growth hormone increased 3-fold as a result of the exercise bout but fell to baseline for all groups by 60 min (p<0.001). Conclusion: The resistance exercise bout was anabolic as shown by the increase in the active eIF4E-eIF4G complex and serum growth hormone. Consumption of MILK 2 led to the most optimal environment for muscle anabolism; however, none of the experimental beverages influenced the measured indicators of muscle protein translation 1-hr after ingestion.
- The effect of protective knee braces on agility and muscle performancePolascik, Michael A. (Virginia Tech, 1989-05-05)Thirty-two Virginia Tech varsity football players served as subjects to examine the effect of protective knee braces on agility and selected isokinetic strength, power, and endurance measures. Each subject performed the Semo agility test in each of three experimental conditions: braced with the Anderson knee stabler (B,An); braced with the Arco knee guard (Bâ Ar); and unbraced (Un). The order of agility tests was randomized. The subjects were than administered a Cybex knee extension/flexion test at 60 deg/sec and 300 deg/sec. Each subject performed the Cybex tests in each of the three experimental conditions (B-An, B-Ar, and Un). The order of Cybex tests was randomized. The test protocol consisted of three maximal repetitions at 60 deg/sec and 40 maximal repetitions at 300 deg/sec. The following isokinetic variables were recorded: (1) peak torque/body weight ratio of the quadriceps and hamstrings at 60 deg/sec and 300 deg/sec; (2) average range of motion for knee extension/flexion at 60 deg/sec and 300 deg/sec; (3) average power, torque acceleration energy, and endurance ratio of the quadriceps and hamstrings at 300 deg/sec. Repeated measures analysis of variance revealed no significant difference (p > .05) in agility test scores between the three experimental conditions. Repeated measures analysis of variance also revealed no significant difference (p > .05) in the isokinetic responses of subjects as they were tested within the three experimental conditions. The investigator concluded that protective knee braces had no effect on agility, isokinetic strength, power, and endurance.
- Effect of Whey Protein Isolate on Oxidative Stress, Exercise Performance, and ImmunityShute, Max (Virginia Tech, 2004-03-04)The purpose of this study was to evaluate the effectiveness of a whey protein isolate (WPI), a reported glutathione (GSH) booster, on exercise performance, immune function, and antioxidant status during weight maintenance and energy restriction in humans. Twenty well-trained, college age, male cyclists performed a cycling exercise test for 45 min, the first 7 min at 70% of VO2peak and the remaining 38 min at 55% VO₂peak immediately followed by a performance test set at 90% VO2peak until exhaustion. Blood samples were collected prior to the exercise test, after 45 min of exercise, within 5 min of exhaustion, and 1 h after exercise. Blood samples were analyzed for GSH, GSH/GSSG ratio, glutathione peroxidase (GPx), lipid hydroperoxides (LPO), phagocytosis, oxidative burst, peripheral blood mononuclear cell (PBMC) proliferation, and PBMC phenotyping. Subjects consumed 40g/day of WPI or casein placebo (P) along with their normal diet for 2 wk, repeated the exercise test, and then began a low energy period continuing the same supplementation for 4 d before the final exercise test. WPI was not associated with superior exercise performance or antioxidant status following exercise or weight loss. WPI supplementation did result in 33% greater lymphocyte proliferation capacity following exercise. Following exhaustive exercise for all trials, tGSH and GPx increased 7% and 11%, respectively, while WBCGSH decreased 13%. For WPI, GPx activity was 10% lower than P following exhaustive exercise for all trials combined. Weight loss (2.67 ± 0.26 kg) resulted in increases in phagocytosis (65%), white blood cell (WBC) GSH (40%), and GPx (35%) while decreasing the GSH/GSSG ratio (55%) and LPO (16%). Exhaustive exercise caused a 28% increase in CD8+ PBMCs and decreased CD4+ (34%), CD3+ (15%), the CD4+/8+ ratio (45%), and phagocytosis (8%) with all values returning to baseline after 1 h recovery. Supplementation with WPI did not enhance GSH status or exercise performance in trained cyclists, during weight maintenance or energy restriction. Following exercise, WPI is associated with greater lymphocyte proliferation of PBMCs which may help maintain an athlete's health during heavy training or competition.
- The Effect of Whey Protein Isolate on Plasma Amino Acids, Nitrogen Balance, Glutathione and Performance during Energy Restriction in AthletesHeffron, Sean Patrick (Virginia Tech, 2004-02-23)This study compared the effects of whey and casein on plasma AA, nitrogen balance (NBAL), glutathione and performance in dieting athletes. Twenty cyclists consumed 40 g·d-1 whey (WHEY) or casein (CAS) for 3 wk. On d 18 – 21 subjects restricted intake to 20 kcal·kg-1·d-1 plus protein supplement. Apparent NBAL was estimated on d 18 – 21 while postabsorptive and 2 h postprandial plasma AA were measured on d 14 and 21. On d 1, 15 and 22 subjects performed an exercise performance test and provided blood for glutathione analysis. Both groups experienced similar negative NBAL (CAS = -19.7 ± 1.4 g, WHEY = -21.4 ± 2.7 g) during energy restriction. There were trends towards a reduction in performance during energy restriction (p = 0.073) and an interaction of group with day (p = 0.072). There were significant main effects of state (postabsorptive = 34.5 ± 2.4 µM, postprandial = 37.1 ± 3.0 µM; p = 0.038) and day (d 14 = 33.8 ± 2.2 µM, d 21 = 37.8 ± 3.2 µM; p = 0.008) on plasma cysteine. There was a significant interaction of state and day on glutamine (p = 0.002), as levels increased 1.3% from postabsorptive to postprandial measurements on d 14, but decreased 4.2% on d 21. The absolute change in postabsorptive cysteine from d 14 to d 21 was correlated with NBAL (r = 0.766, p = 0.01) in CAS but not in WHEY. Plasma glutamine did not correlate with NBAL in either group.
- Effects of a dietary milk or carbohydrate supplement with resistance training on body composition, muscle strength and anabolic hormones in untrained menGoldman, Lauren Paige (Virginia Tech, 2001-12-10)Twenty untrained men (18-25 y) were assigned to consume either a milk supplement (MILK) or a carbohydrate-electrolyte supplement (CHO) immediately following each resistance workout during a 10 wk resistance training program. Subjects trained 3 d/wk beginning with an intensity of 55% 1-RM and progressing to 97% 1-RM by wk 10. Muscle strength (1-RM), body composition (DEXA) and resting, fasted serum concentrations of total and free testosterone and IGF-1 were measured pre- and post-training. CHO tended to reduce, while MILK increased body weight (P = 0.10). All subjects significantly reduced percent body fat (1.1%) and significantly increased lean body mass (1.21 kg) as a result of the resistance training with no significant differences between treatments. However, MILK tended to increase lean body mass (P = 0.1) more than CHO (1.6 and 0.8 kg, respectively). About 39% of lean mass gain for all subjects was in the leg region, while the arms accounted for about 28% of lean gain. Resistance training also caused a similar significant 44% increase in muscle strength for the seven exercises combined for both groups. Resting total and free testosterone concentrations significantly decreased from baseline values in both groups of subjects (16.7% and 11%, respectively), while resting insulin concentrations significantly increased in all subjects (P<0.01). There were no significant changes in resting, fasted IGF-1 concentrations. In summary, dietary supplementation with a MILK or CHO beverage immediately following resistance exercise resulted in similar changes in muscle strength and hormone concentrations following a 10 wk periodized resistance training program. MILK tended to increase body weight and lean body mass more so than CHO.
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