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Nicholas J. Hanson, Sarah C. Martinez, Erik N. Byl, Rachel M. Maceri, and Michael G. Miller

Purpose: Although the effect of caffeine in thermoneutral or cool environmental conditions has generally shown performance benefits, its efficacy in hot, humid conditions is not as well known. The purpose of this study was to further examine the effect of caffeine ingestion on endurance running performance in the heat. Methods: Ten trained endurance runners (6 males; mean [SD] age = 26 [9] y, height = 176.7 [5.1] cm, and mass = 72.1 [8.7] kg) came to the lab for 4 visits. The first was a VO2max test to determine cardiorespiratory fitness; the final 3 visits were 10-km runs in an environmental chamber at 30.6°C and 50% relative humidity under different conditions: 3 mg·kg−1 body mass (low caffeine dosage), 6 mg·kg−1 (moderate caffeine dosage), and a placebo. Repeated-measures analyses of variance were used to determine the effect of condition on the 10-km time, heart rate, core temperature, rating of perceived exertion, and thermal sensation. Results: There was no difference in the 10-km time between the placebo (53.2 [8.0] min), 3-mg·kg−1 (53.4 [8.4]), and 6-mg·kg−1 (52.7 [8.2]) conditions (P = .575, ηp2=.060). There was not a main effect of average heart rate (P = .406, ηp2=.107), rating of perceived exertion (P = .151, ηp2=.189), or thermal sensation (P = .286, ηp2=.130). There was a significant interaction for core temperature (P = .025, ηp2=.170); the moderate-dosage caffeine condition showed a higher rate of rise in core temperature (0.26 [0.08] °C·km−1 vs 0.20 [0.06] and 0.19 [0.10] °C·km−1 in the low-caffeine and placebo conditions, respectively). Conclusion: The results support previous research showing a thermogenic effect of caffeine, as the moderate-dosage condition led to a greater rate of heat storage and no performance benefits.

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David C. Berry and Michael G. Miller

Edited by Malissa Martin

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Aimee E. Roth, Michael G. Miller, Marc Ricard, Donna Ritenour, and Brenda L. Chapman

Context:

It has been theorized that aquatic balance training differs from land balance training.

Objective:

To compare the effects of balance training in aquatic and land environments.

Design:

Between-groups, repeated-measures design.

Setting:

Biomechanics laboratory and pool.

Participants:

24 healthy subjects randomly assigned to aquatic (n = 8), land (n = 10), or control (n = 6) groups.

Intervention:

Four weeks of balance training.

Main Outcome Measures:

Balance was measured (pre, mid, post, follow-up). COP variables: radial area, y range, x range in single leg (SL), tandem (T), single leg foam (SLF), and tandem form (TF) stance.

Results:

A significant condition × time interaction for x range was found, with improvements for SL, SLF, and TF. Radial area improved, with post-test 1.01 ± .23 cm2 and follow-up 1.06 ± .18 cm2 significantly lower than pretest 1.18 ± .23 cm2. Y range significantly improved, with posttest (4.69 ± 1.02 cm2) lower than pretest (5.89 ± 1.26 cm2). The foam conditions (SLF & TF) were significantly different from non-foam conditions (SL & T) for all variables.

Conclusions:

Results of this study show that balance training can effectively be performed in both land and aquatic environments.

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Michael G. Miller, Christopher C. Cheatham, William R. Holcomb, Rosealin Ganschow, Timothy J. Michael, and Mack D. Rubley

Context:

No direct research has been conducted on the relationship between subcutaneous tissue thickness and neuromuscular electrical stimulation (NMES).

Objective:

The purpose of this study was to determine the effects of subcutaneous tissue thickness on NMES amplitude and NMES force production of the quadriceps.

Design:

Simple fixed design, testing the independent variable of subcutaneous thickness (skinfold) groups with the dependent variables of NMES amplitude and force production.

Setting:

Athletic Training Laboratory.

Participants:

29 healthy women.

Intervention:

NMES to produce at least 30% of maximal voluntary isometric contractions (MVIC) of the quadriceps.

Main Outcome Measure:

Maximal NMES amplitude and percentage of MVIC using NMES.

Results:

A significant skinfold category difference F2,28 = 3.92, P = .032 on NMES amplitude was found. Post hoc revealed the thinnest skinfold category tolerated less amplitude compared to the thickest category. A significant correlation was found between NMES amplitude skinfold category R = .557, P = .002.

Conclusion:

Higher NMES amplitudes are needed for the thickest skinfold category compared to the thinnest skinfold category.

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Giampietro L. Vairo, Sayers John Miller, and Nicole M. McBrier

Edited by Michael G. Dolan