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Larry Tucker and Travis Peterson

Background:

This study was conducted to determine if cardiorespiratory fitness at baseline, and changes in fitness, influence risk of weight gain (≥3 kg) over 20 months. Another aim was to ascertain if potential confounding factors, including age, education, strength training, energy intake, and weight, influence risk of weight gain.

Methods:

In a prospective study of 257 women, fitness (VO2max) was assessed using a graded, maximal treadmill test at baseline and follow-up. Energy intake was measured using 7-day, weighed food records. Subjects were divided into quartiles based on fitness. Risk ratios were used to show the risk of weight gain among those who were fit at baseline compared with their counterparts.

Results:

Most women gained weight and 23% gained ≥3 kg. Mean VO2max was 35.7 ± 7.2 mL·kg−1·min−1. Women with low-fitness at baseline had 3.18 times (95% CI: 1.46 to 6.93) greater risk, and moderately fit women had 2.24 times (95% CI: 1.04 to 4.82) greater risk of weight gain than women in the high-fitness quartile. Adjusting for potential confounders had little effect on results.

Conclusions:

High levels of fitness seem to help protect middle-aged women against weight gain, whereas low and moderate fitness increase risk of weight gain over time.

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Lance E. Davidson, Larry Tucker and Travis Peterson

Background:

The influence of physical activity (PA) changes on risk of abdominal fat gain in midlife women has not been studied using objective measures and controlling for potentially confounding variables.

Methods:

Changes in PA were assessed within a prospective cohort of 233 middle-age (40 ± 3 years), nonobese, nonsmoking, primarily Caucasian women by using accelerometers, worn continuously for 7 consecutive days at baseline and again at a 20 month follow-up. Weighed food intake diaries were completed on concurrent days. Bod Pod assessed total body fat. Abdominal fat was measured by abdominal circumference at the umbilicus.

Results:

Women who decreased PA gained abdominal fat across 20 months, while women who increased PA (F = 4.82, P = .009) did not. Change in PA remained an independent predictor of abdominal fat change after adjusting for potential confounders, including changes in total body fat and total energy intake. Compared with women who maintained or decreased PA, women who increased PA had approximately half the risk (RR = 0.52, 95% CI: 0.27, 0.98) of gaining abdominal fat.

Conclusions:

Increasing daily physical activity may attenuate risk of abdominal fat gain in middle-age women independent of changes in total body fat or energy intake.

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Travis J. Peterson and Jill L. McNitt-Gray

Golf shots off uneven terrain often require modifications in address position to complete the swing successfully. This study aimed to determine how golf players coordinate the legs to regulate linear and angular impulse (about an axis passing vertically through the center of mass) while modifying the lower-extremity address position during the swing. Nine highly skilled golf players performed swings with a 6-iron under the Normal, Rear Leg Up, and Target Leg Up conditions. Components of linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force, resultant horizontal reaction force angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse did not change between conditions. Target leg angular impulse was greater in the Target Leg Up condition than Rear Leg Up condition. Regulation of linear and angular impulse generation occurred while increasing stance width and redirecting resultant horizontal reaction forces to be more parallel to the target line under modified address positions. Net linear impulse perpendicular to the target was near 0 or slightly posterior. Net linear impulse parallel to the target was less toward the target in the Target Leg Up condition compared with Normal and Rear Leg Up conditions. These results indicate individuals utilized player-specific mechanisms to coordinate the legs and regulate impulse generation during the golf swing under modified address positions.

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Travis J. Peterson, Rand R. Wilcox and Jill L. McNitt-Gray

Our aim was to determine how skilled players regulate linear and angular impulse while maintaining balance during the golf swing. Eleven highly-skilled golf players performed swings with a 6-iron and driver. Components contributing to linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force [RFh], RFh-angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse generated by both the rear and target legs was greater for the driver than the 6-iron. Mechanisms used to regulate angular impulse generation between clubs varied across players and required coordination between the legs. Increases in net angular impulse with a driver involved increases in target leg RFh. Rear leg RFh-angle was maintained between clubs whereas target leg RFh became more aligned with the target line. Net linear impulse perpendicular to the target line remained near zero, preserving balance, while net linear impulse along the target line decreased in magnitude. These results indicate that the net angular impulse was regulated between clubs by coordinating force generation of the rear and target legs while sustaining balance throughout the task.

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Rand Wilcox, Travis J. Peterson and Jill L. McNitt-Gray

The paper reviews advances and insights relevant to comparing groups when the sample sizes are small. There are conditions under which conventional, routinely used techniques are satisfactory. But major insights regarding outliers, skewed distributions, and unequal variances (heteroscedasticity) make it clear that under general conditions they provide poor control over the type I error probability and can have relatively poor power. In practical terms, important differences among groups can be missed and poorly characterized. Many new and improved methods have been derived that are aimed at dealing with the shortcomings of classic methods. To provide a conceptual basis for understanding the practical importance of modern methods, the paper reviews some modern insights related to why methods based on means can perform poorly. Then some strategies for dealing with nonnormal distributions and unequal variances are described. For brevity, the focus is on comparing 2 independent groups or 2 dependent groups based on the usual difference scores. The paper concludes with comments on issues to consider when choosing from among the methods reviewed in the paper.

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James D. LeCheminant, Larry A. Tucker, Bruce W. Bailey and Travis Peterson

Purpose:

To determine objectively measured intensity of physical activity (iPA) and its relationship to high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and the LDL/HDL ratio in women.

Methods:

Two hundred seventy-two women (40.1 y) wore CSA-MTI model 7164 accelerometers to index intensity and volume of physical activity for 7 d. Blood lipids were measured at a certified laboratory.

Results:

HDL-C was 52.1 ± 10.1, 52.2 ± 9.7, and 56.1 ± 11.1 mg/dL for the low, medium, and high intensity groups (P = 0.040), LDL-C differences were not significant (P = 0.23). LDL/HDL differences were observed (P = 0.030) with specific differences between the low and high iPA groups (P = 0.006). For HDL-C and LDL/HDL, significant relationships remained with control of dietary fat and age but not body fat percentage or volume of activity.

Conclusions:

High iPA had higher HDL-C levels and lower LDL/HDL ratios than low and medium iPA. The iPA was predictive of HDL-C partly due to its strong association with volume of activity and body fat percentage.