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  • Author: Karen L. Nau x
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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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Karen L. Nau, Victor L. Katch, Robert H. Beekman and Macdonald Dick II

Intraarterial blood pressure (BP) response to bench press weight lifting (WL) was evaluated in 11 children. Aortic systolic and diastolic pressures and heart rate (HR) were measured during WL. Baseline systolic and diastolic pressures were 120 and 81 mmHg, and HR was 86 bpm. Subjects lifted to voluntary fatigue weights equaling 60, 75, 90, and 100% of their predetermined one-repetition maximum (1RM). For each weight lifting condition, BP and HR increased as more repetitions were completed. Peak systolic pressure was 168, 177, 166, and 162 mmHg, peak diastolic pressure was 125, 139, 133, and 130 mmHg, and peak heart rate was 142, 148, 142, and 139 bpm at 60, 75, 90, and 100% 1RM, respectively. Peak BP and HR were greater during WL than rest but did not differ between conditions. The relative BP response to WL in children was similar to adult values. For all conditions, pressures increased as more repetitions were completed. It was concluded that peak pressures occur at voluntary fatigue, independent of the combination of resistance and repetitions used to achieve fatigue.

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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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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.