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  • Author: Jeffrey A. Potteiger x
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Marcia A. Chan, Alexander J. Koch, Stephen H. Benedict and Jeffrey A. Potteiger

The effect of carbohydrate supplementation (CHO) on interleukin 2 (IL-2) and interleukin 5 (IL-5) secretion following acute resistance exercise was examined in 9 resistance-trained males. Subjects completed a randomized, double-blind protocol with exercise separated by 14 days. The exercise consisted of a high intensity, short rest interval squat workout. Subjects consumed 1.0 g · kg body mass-1 CHO or an equal volume of placebo (PLC) 10 min prior to and 10 min following exercise. Blood was collected at rest (REST), immediately post exercise (POST), and at 1.5 h of recovery (1.5 h POST). Isolated peripheral blood mononuclear cells were stimulated with PHA and assayed for IL-2 and IL-5 secretion. IL-2 secretion was significantly decreased at POST for both the PLC and CHO groups. However, the degree of decrease was less in the CHO group (16%) than in the PLC group (48%), and this difference was statistically significant. These responses were transient, and the values returned to normal by 1.5 h POST. A mild and transient but significant decrease in IL-5 secretion by the PLC group was observed at POST (26%) compared to REST. No significant decrease was observed in IL-5 secretion for CHO from REST to POST (12%). These data support a possible effect of carbohydrate supplementation on IL-2 and IL-5 secretion following high-intensity resistance exercise.

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Alexander J. Koch, Jeffrey A. Potteiger, Marcia A. Chan, Stephen H. Benedict and Bruce B. Frey

The effect of carbohydrate supplementation (CHO) on the lymphocyte response to acute resistance exercise was examined in 10 resistance-trained males. Subjects completed a randomized double-blind protocol with sessions separated by 14 days. The exercise session consisted of a high intensity, short rest interval squat workout. Subjects consumed 1.0 g · kg body mass−1 CHO or an equal volume of placebo (PLC) 10 min prior to and 10 min following exercise. Blood was collected at rest (REST), immediately post exercise (POST), and at 1.5 hours and 4.0 hours of recovery, and analyzed for plasma glucose, serum cortisol, leukocyte subsets, and phytohemagglutinin (PHA)-stimulated lymphocyte proliferation. A significant Treatment × Time effect was observed for lymphocyte proliferation between CHO and PLC, but post hoc analyses revealed no between-treatment differences at any post-exercise time point. Lymphocyte proliferation was significantly depressed below REST at POST (−39.2% for PLC, −25.7% for CHO). Significant fluctuations in leukocyte subset trafficking were observed for both treatments at POST, 1.5 hours, and 4.0 hours. Plasma glucose was significantly increased POST in CHO compared to PLC. Cortisol was significantly increased from REST to POST in both treatments. These data support a minimal effect of carbohydrate ingestion on the lymphocyte response to high-intensity resistance exercise.

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Jay L. Tuttle, Jeffrey A. Potteiger, Blanche W. Evans and John C. Ozmun

This study examined the effects of aspartate supplementation (ASP) on plasma ammonia concentrations ([NH4+]) during and after a resistance training workout (RTW). Twelve male weight trainers were randomly administered ASP or vitamin C in a crossover, double blind protocol, each trial separated by 1 wk. ASP and vitamin C were given over a 2-hr period beginning 5 hr prior to the RTW. The RTW consisted of bench, incline, shoulder, and triceps presses, and biceps curls at 70% of one repetition maximum (1-RM). After the RTW a bench press test (BPT) to failure at 65% of 1-RM was used to assess performance. [NH4+] was determined preexercise, 20 and 40 min midworkout, immediately postexercise, and 15 min postexercise. Treatment-by-time ANOVAs, paired t tests, and contrast comparisons were used to identify mean differences. No significant differences were observed between treatments for [NH4+] or BPT. [NH4+] increased significantly from Pre to immediately postexercise for both the ASP and vitamin C trials. Acute ASP supplementation does not reduce [NH4+] during and after a high intensity RTW in weight trained subjects.

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Kristen L. Heck, Jeffrey A. Potteiger, Karen L. Nau and Jan M. Schroeder

We examined the effects of sodium bicarbonate ingestion on the VO2 slow component during constant-load exercise. Twelve physically active males performed two 30-min cycling trials at an intensity above the lactate threshold. Subjects ingested either sodium bicarbonate (BIC) or placebo (PLC) in a randomized. counterbalanced order. Arterialized capillary blood samples were analyzed for pH, bicarbonate concentration ([HCO3 ), and lactate concentration ([La]). Expired gas samples were analyzed for oxygen consumption (VO2). The VO2 slow component was defined as the change in VO2 from Minutes 3 and 4 to Minutes 28 and 29. Values for pH and [HCO3 ] were significantly higher for BIC compared to PLC. There was no significant difference in [La] between conditions. For both conditions there was a significant time effect for VO2 during exercise: however, no significant difference was observed between BIC and PLC. While extracellular acid-base measures were altered during the BIC trial, sodium bicarbonate ingestion did not attenuate the VO2 slow component during constant-load exercise.

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Jeffrey A. Potteiger, Erik P. Kirk, Dennis J. Jacobsen and Joseph E. Donnelly

Purpose:

To determine whether 16 months of moderate-intensity exercise training changes resting metabolic rate (RMR) and substrate oxidation in overweight young adults.

Methods:

Participants were randomly assigned to nonexercise control (CON, 18 women, 15 men) or exercise (EX, 25 women, 16 men) groups. EX performed supervised and verified exercise 3–5 d/wk, 20–45 min/session, at 60–75% of heart-rate reserve. Body mass and composition, maximal oxygen consumption (VO2max), RMR, and resting substrate oxidation were assessed at baseline and after 9 and 16 months of training.

Results:

EX men had significant decreases from baseline to 9 months in body mass (94.6 ± 12.4 to 89.2 ± 9.5 kg) and percent fat (28.3 ± 4.6 to 24.5 ± 3.9). CON women had significant increases in body mass (80.2 ± 8.1 to 83.2 ± 9.2 kg) from baseline to 16 months. VO2max increased significantly from baseline to 9 months in the EX men (3.67 ± 0.62 to 4.34 ± 0.58 L/min) and EX women (2.53 ± 0.32 to 3.03 ± 0.42 L/min). RMR increased from baseline to 9 months in EX women (1,583 ± 221 to 1,692 ± 230 kcal/d) and EX men (1,995 ± 184 to 2,025 ± 209 kcal/d). There were no significant differences within genders for either EX or CON in fat or carbohydrate oxidation. Fat oxidation was significantly higher for women than for men at 9 months in both CON and EX groups.

Conclusions:

Regular moderate-intensity exercise in healthy, previously sedentary overweight and obese adults increases RMR but does not alter resting substrate oxidation. Women tend to have higher RMR and greater fat oxidation, when expressed per kilogram fat-free mass, than men.

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Jan M. Schroeder, Karen L. Nau, Wayne H. Osness and Jeffrey A. Potteiger

Measurements of functional ability, balance, strength, flexibility, life satisfaction, and physical activity were compared among three populations of older adults (age 75-85 years). Sixty-nine subjects performed the Physical Performance Test (PPT). timed Up and Go. 1 repetition maximum (IRM) leg press and extensions, and Modified Sit and Reach. The Physical Activity Questionnaire for the Elderly and Satisfaction With Life Scale were also completed. No difference was found among the groups for life satisfaction. Individuals living in a nursing facility had poorer PPT scores, dynamic balance, leg extension strength, leg press strength, flexibility, and physical activity than individuals living in assisted-care facilities and the community. Assisted-care individuals had significantly lower PPT scores and leg strength than community-living individuals. The decline of ADL performance and physical activity may be accounted for by loss of strength, balance, and flexibility, all associated with a loss of independence.

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Keith A. Shannon, Robynn M. Shannon, John N. Clore, Chris Gennings, Beverly J. Warren and Jeffrey A. Potteiger

Purpose:

To determine whether ethnicity influences postprandial lipemia after a bout of aerobic exercise.

Methods:

Randomized crossover design. Healthy White (W; n = 6) and African American (AA; n = 6) women (age, W 27.0 ± 3.3 yr, AA 21.6 ± 1.4 yr; body-mass index, W 25.0 ± 0.93 kg/m2, AA 25.8 ± 0.79 kg/m2) participated in 2 treatments (control and exercise), each conducted over 2 d. On d 1, participants rested (control) or walked at 60% of maximal oxygen uptake for 90 min (exercise) and then consumed a meal. On d 2, after a 12-hr overnight fast, participants consumed an oral fat-tolerance test (OFTT) meal of 1.7 g fat, 1.65 g carbohydrate, and 0.25 g protein per kg fat-free mass. Blood was collected premeal and at 0.5, 1, 2, 3, 4, 5, and 6 hr post-OFTT and analyzed for triacylglycerol (TAG), glucose, and insulin. Areas under the curve (AUCs) were calculated for each blood variable.

Results:

A significantly lower TAG AUC was observed for AA (0.86 ± 0.24 mmol · L−1 · 6 hr−1) after exercise than for W (2.25 ± .50 mmol · L−1 · 6 hr−1). Insulin AUC was significantly higher for AA after exercise (366.2 ± 19.9 mmol · L−1 · 6 hr−1) than for the control (248.1 ± 29.2 mmol · L−1 · 6 hr−1).

Conclusions:

The data indicate that exercise performed ~13 hr before an OFTT significantly reduces postprandial lipemia in AA compared with W. It appears that AA women have an increased ability to dispose of TAG after exercise and a high-fat meal.

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Mark D. Haub, Jeffrey A. Potteiger, Dennis J. Jacobsen, Karen L. Nau, Lawrence A. Magee and Matthew J. Comeau

We investigated the effects of carbohydrate ingestion on glycogen replenishment and subsequent short duration, high intensity exercise performance. During Session 1, aerobic power was determined and each subject (N = 6) was familiarized with the 100-kJ cycling test (lOOKJ-Test). During the treatment sessions, the subjects performed a lOOKJ-Test (Ride-1), then consumed 0.7 g ⋅ kg body mass-1 of maltodextrin (CHO) or placebo (PLC), rested 60 min, and then performed a second lOOKJ-Test (Ride-2). Muscle tissue was collected before (Pre-1) and after Ride-1 (Post-1), and before (Pre-2) and after Ride-2 (Post-2), and analyzed for glycogen concentration. Both treatments yielded a significant increase in glycogen levels following the 60-min recovery, but there was no difference between treatments. Time to complete the lOOKJ-Test increased significantly for PLC, but not for CHO. These data indicate that the decrease in performance during Ride-2 in PLC was not the result of a difference in glycogen concentration.

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Vincent G. Stilger, Jeffrey A. Potteiger, Betsey Schmidt and Robert D. Chetlin

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G. Gregory Haff, Alexander J. Koch, Jeffrey A. Potteiger, Karen E. Kuphal, Lawrence M. Magee, Samuel B. Green and John J. Jakicic

The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.