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  • Author: John R. Miller x
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Diana E. Thomas, John R. Brotherhood and Janette Brand Miller

It was hypothesized that slowly digested carbohydrates, that is, low glycemic index (GI) foods, eaten before prolonged strenuous exercise would increase the blood glucose concentration toward the end of exercise. Six trained cyclists pedaled on a cycle ergometer at 65-70% VO2max 60 min after ingestion of each of four test meals: a low-GI and a high-GI powdered food and a low-GI and a high-GI breakfast cereal, all providing 1 g of available carbohydrate per kilogram of body mass. Plasma glucose levels after more that 90 min of exercise were found to correlate inversely with the observed GI of the foods (p < .01). Free fatty acid levels during the last hour of exercise also correlated inversely with the GI (p < .05). The findings suggest that the slow digestion of carbohydrate in the preevent food favors higher concentrations of fuels in the blood toward the end of exercise.

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Alseny Balde, Jaime Figueras, Dawn A. Hawking and John R. Miller

Lack of physical activity is an increasing public-health problem. Physicians should counsel elderly patients to maintain regular physical activity in order to retain functionality and quality of life. This study examined the patterns of physician advice about physical activity in an elderly population. A homogeneous group of older adults living in public housing (N = 146) was surveyed to determine the extent to which they received such advice. Their mean age was 77.9 ± 7 years, 74% were women, 70.5% were White, and 53.4% had high school education or less. We assessed the association between physician counseling practices and the participants’ demographic characteristics, overweight status, and type of physical activity performed. The prevalence rate of physician counseling was 61.6%. Elderly men who were married and those who were overweight were most likely to receive advice. Routine physician counseling of elderly patients regardless of overweight status could contribute to improving their quality of life.

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Jay Hertel, S. John Miller and Craig R. Denegar

0bjective:

To estimate intratester and intertester reliability and learning effects during the Star Excursion Balance Tests (SEBTs).

Setting:

A university athletic training research laboratory.

Subjects:

Sixteen healthy volunteers with no history of balance disorders or significant lower extremity joint pathology.

Measurements:

Length of excursion was measured manually for each trial.

Results:

ICCs for intratester reliability were .78–.96 on day 1 and 32–.96 on day 2. ICCs for intertester reliability were .35–.84 on day 1 and .81–.93 on day 2. Significant learning effects were identified for 4 of the 8 tests.

Conclusions:

Estimates of intratester and intertester reliability were high, but adequate practice trials should be performed before taking baseline measures.

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Graig R. Denegar, Jay Hertel and Sayers John Miller

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Thomas P. Dompier, Craig R. Denegar, W.E. Buckley, S. John Miller, Jay Hertel and Wayne J. Sebastianelli

Context:

Flexibility is promoted as essential to physical fitness, but the mechanisms limiting it are not fully understood.

Objective:

To investigate the effects of general anesthesia on hamstring extensibility.

Design:

Repeated measures.

Setting:

Hospital operating room.

Subjects:

Eight volunteers undergoing orthopedic surgeries unrelated to the tested limb.

Measurement:

Three measurements of passive knee extension (PKE) taken before and after administration of general anesthesia. The force applied during the measurements was consistent between trials.

Results:

Mean PKE range of motion (ROM) was significantly greater before anesthesia (75.0° ± 11.8°) than after (53.3° ± 17°; t = 5.6, P < .001). Pearson product correlation revealed a significant correlation between the mean difference in PKE ROM between treatment conditions and subjects’ body weight (r = .91, P < .05).

Conclusions:

The findings might be attributable to diminished neural drive to the antagonist muscle groups and suggest a more complex neural control of flexibility than simply neural drive to an agonist muscle.

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Lindsey E. Miller, Graham R. McGinnis, Brian Kliszczewicz, Dustin Slivka, Walter Hailes, John Cuddy, Charles Dumke, Brent Ruby and John C. Quindry

Oxidative stress occurs as a result of altitude-induced hypobaric hypoxia and physical exercise. The effect of exercise on oxidative stress under hypobaric hypoxia is not well understood.

Purpose:

To determine the effect of high-altitude exercise on blood oxidative stress. Nine male participants completed a 2-d trek up and down Mt Rainer, in North America, at a peak altitude of 4,393 m. Day 1 consisted of steady-pace climbing for 6.25 hr to a final elevation of 3,000 m. The 4,393-m summit was reached on Day 2 in approximately 5 hr. Climb–rest intervals varied but were consistent between participants, with approximately 14 hr of total time including rest periods. Blood samples were assayed for biomarkers of oxidative stress and antioxidant potential at the following time points: Pre (before the trek), 3Kup (at ascent to 3,000 m), 3Kdown (at 3,000 m on the descent), and Post (posttrek at base elevation). Blood serum variables included ferric-reducing antioxidant potential (FRAP), Trolox equivalent antioxidant capacity (TEAC), protein carbonyls (PC), and lipid hydroperoxides. Serum FRAP was elevated at 3Kup and 3Kdown compared with Pre and Post values (p = .004, 8% and 11% increase from Pre). Serum TEAC values were increased at 3Kdown and Post (p = .032, 10% and 18% increase from Pre). Serum PC were elevated at 3Kup and 3Kdown time points (p = .034, 194% and 138% increase from Pre), while lipid hydroperoxides were elevated Post only (p = .004, 257% increase from Pre).

Conclusions:

Findings indicate that high-altitude trekking is associated with increased blood oxidative stress.

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Jessica L. Unick, Michael P. Walkup, Michael E. Miller, John W. Apolzan, Peter H. Brubaker, Mace Coday, James O. Hill, John M. Jakicic, Roeland J.W. Middelbeek, Delia West, Rena R. Wing and the Look AHEAD Research Group

Background: To examine the relationship between early physical activity (PA) adoption (2, 3, and 4 mo) and longer-term PA adherence (1 y) among individuals who were inactive at baseline and received a lifestyle intervention. Methods: Participants (n = 637) received weekly behavioral weight loss sessions, calorie reduction, and PA goals (50–175 min/wk progression). PA was assessed via self-reported measures at baseline, months 2 to 4, and 1 year. Results: PA at months 2 to 4 was significantly correlated with PA at 1 year (rs = .29–.35, P < .01). At all early time points, those failing to meet the prescribed PA goal (early nonadopters) engaged in significantly less PA at 1 year than those meeting the early PA goal (initial adopters). For example, using 2-month criteria, initial adopters engaged in 108.3 minutes per week more at 1 year compared with early nonadopters (P < .01) and had 2.8 times the odds (95% confidence interval, 1.9–4.2) of meeting the 1-year PA goal (≥175 min/wk, P < .01). Conclusions: Failure to achieve PA goals at 2, 3, or 4 months results in less overall PA at 1 year. Thus, PA observed as early as month 2 may be a useful indicator for identifying at-risk individuals who may benefit from more intensive PA intervention strategies.