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Masashi Miyashita, Stephen Francis Burns and David John Stensel

Background:

This study examined the effect of accumulating short bouts of exercise on postprandial plasma triacylglycerol and resting blood pressure in healthy young men.

Methods:

Nineteen subjects underwent two 2-d trials in a randomized counterbalanced order. On day 1, subjects either rested or performed multiple 6 min running bouts (30 min rest between each) until they had accumulated an energy expenditure of 4.2 MJ (1000 kcal). On day 2, subjects rested and consumed test meals for breakfast and lunch. Blood pressure was measured throughout days 1 and 2. Venous blood samples were obtained throughout day 2.

Results:

Systolic and diastolic blood pressure was lower for the exercise compared with the control trial on day 1. Postprandial plasma triacylglycerol concentrations and systolic blood pressure were lower throughout day 2 on the exercise compared with the control trial.

Conclusion:

Accumulating short bouts of exercise throughout the day may modify cardiovascular disease risk.

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Kenneth R. Turley, D. Eric Martin, Eric D. Marvin and Kelley S. Cowley

To determine the reliability of cardiovascular responses to isometric exercise of different intensities, and to compare adult versus child responses, 27 boys (7–9 years old) and 27 men (18–26 years old) performed static handgrip exercise at 10, 20, and 30% of previously determined maximal voluntary contraction (MVC) for three min each on different days, while heart rate (HR) and blood pressure (BP) were measured. HR reliability was moderately high at all intensities in both boys and men ranging from R = 0.52–0.87. BP reliability was moderate in men and boys at 30% MVC while at 10% and 20% MVC reliability was very low for boys and only moderate for men. HR response from pre- to 3-min of static exercise was not different between boys versus men at any intensity. At 30% MVC diastolic (20.2 vs. 29.3 mmHg), systolic (17.4 vs. 36.2 mmHg) and mean (19.2 vs. 31.6 mmHg) BP responses were lower in boys versus men, respectively. At 20% MVC SBP (6.8 vs. 14.3 mmHg) and MBP (8.4 vs. 12.6 mmHg) responses were lower in boys versus men, respectively. In conclusion, the reliability of cardiovascular response to isometric exercise is low at low contraction intensities and moderate at higher contraction intensities. Further, BP response in men at 30% MVC is higher than boys, while responses are similar at lower contraction intensities.

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Bente R. Jensen, Line Hovgaard-Hansen and Katrine L. Cappelen

Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle).It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force.

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Martin J. Turner, Marc V. Jones, David Sheffield, Matthew J. Slater, Jamie B. Barker and James J. Bell

This study assessed whether cardiovascular (CV) reactivity patterns indexing challenge and threat states predicted batting performance in elite male county (N = 12) and national (N = 30) academy cricketers. Participants completed a batting test under pressure, before which CV reactivity was recorded in response to ego-threatening audio instructions. Self-reported self-efficacy, control, achievement goals, and emotions were also assessed. Challenge CV reactivity predicted superior performance in the Batting Test, compared with threat CV reactivity. The relationships between self-report measures and CV reactivity, and self-report measures and performance were inconsistent. A small subsample of participants who exhibited threat CV reactivity, but performed well, reported greater self-efficacy than participants who exhibited threat CV reactivity, but performed poorly. Also a small subsample of participants who exhibited challenge reactivity, but performed poorly, had higher avoidance goals than participants with challenge reactivity who performed well. The mechanisms for the observed relationship between CV reactivity and performance are discussed alongside implications for future research and applied practice.

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Chris Englert, Kris Zwemmer, Alex Bertrams and Raôul R.D. Oudejans

In the current study we investigated whether ego depletion negatively affects attention regulation under pressure in sports by assessing participants’ dart throwing performance and accompanying gaze behavior. According to the strength model of self-control, the most important aspect of self-control is attention regulation. Because higher levels of state anxiety are associated with impaired attention regulation, we chose a mixed design with ego depletion (yes vs. no) as between-subjects and anxiety level (high vs. low) as within-subjects factor. Participants performed a perceptual-motor task requiring selective attention, namely, dart throwing. In line with our expectations, depleted participants in the high-anxiety condition performed worse and displayed a shorter final fixation on bull’s eye, demonstrating that when one’s self-control strength is depleted, attention regulation under pressure cannot be maintained. This is the first study that directly supports the general assumption that ego depletion is a major factor in influencing attention regulation under pressure.

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Mark R. Wilson, Samuel J. Vine and Greg Wood

The aim of this study was to test the predictions of attentional control theory using the quiet eye period as an objective measure of attentional control. Ten basketball players took free throws in two counterbalanced experimental conditions designed to manipulate the anxiety they experienced. Point of gaze was measured using an ASL Mobile Eye tracker and fixations including the quiet eye were determined using frame-by-frame analysis. The manipulation of anxiety resulted in significant reductions in the duration of the quiet eye period and free throw success rate, thus supporting the predictions of attentional control theory. Anxiety impaired goal-directed attentional control (quiet eye period) at the expense of stimulus-driven control (more fixations of shorter duration to various targets). The findings suggest that attentional control theory may be a useful theoretical framework for examining the relationship between anxiety and performance in visuomotor sport skills.

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Bakhtyar Tartibian, Ana Maria Botelho Teixeira and Behrouz Baghaiee

Purpose:

The purpose of the current study was to characterize the role of aerobic exercise in the gene expression of the angiotensin-converting enzyme (ACE) and the β2-adrenergic receptor (ADRB2) in untrained men.

Methods:

Twenty untrained middle-aged men were randomly assigned to exercise (Exe) and control (Con) groups. The Exe group performed aerobic exercises for eight weeks. ACE mRNA and ADRB2 mRNA were determined by PCR.

Results:

The expression of ACE in week 4 and in the Exe group decreased significantly (p < .001). ADRB2 in the Exe group, in week 4 and in week 8, was markedly higher, and blood pressure was significantly lower than in the Con group (p < .001). In the Con group ADRB2 mRNA decreased.

Conclusion:

These results suggest that moderate intensity exercise promotes the leukocyte expression of gene markers that may affect blood pressure by improving cardiovascular fitness levels in middle-aged men.

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Ashley Gibson Bowers, Christina L.L. Martin, John Miller, Brent Wolfe and Nancy Magee Speed

The purpose of the study was to examine female athletes’ perceptions of their body image as a result of comparing themselves to others. Social comparison theory (Festinger, 1954) was used as the theoretical basis for understanding the effects of body image among intercollegiate female athletes. Using a qualitative analysis, the authors individually interviewed 20 female collegiate athletes attending a Division I university and thematically coded their responses. The findings suggest that coaches and teammates significantly contribute to body image pressures in female athletes, as participants were sensitive to the comments and perceptions of these groups. Finally, athletes perceived that the external population (those outside of coaches and teammates) evaluated athletic talent based on actual body image.

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Mary O. Hearst, John R. Sirard, Leslie Lytle, Donald R. Dengel and David Berrigan

Background:

The association of physical activity (PA), measured 3 ways, and biomarkers were compared in a sample of adolescents.

Methods:

PA data were collected on 2 cohorts of adolescents (N = 700) in the Twin Cities, Minnesota, 2007–2008. PA was measured using 2 survey questions [Modified Activity Questionnaire (MAQ)], the 3-Day Physical Activity Recall (3DPAR), and accelerometers. Biomarkers included systolic (SBP) and diastolic blood pressure (DBP), lipids, percent body fat (%BF), and body mass index (BMI) percentile. Bivariate relationships among PA measures and biomarkers were examined followed by generalized estimating equations for multivariate analysis.

Results:

The 3 measures were significantly correlated with each other (r = .22–.36, P < .001). Controlling for study, puberty, age, and gender, all 3 PA measures were associated with %BF (MAQ = −1.93, P < .001; 3DPAR = −1.64, P < .001; accelerometer = −1.06, P = .001). The MAQ and accelerometers were negatively associated with BMI percentile. None of the 3 PA measures were significantly associated with SBP or lipids. The percentage of adolescents meeting the national PA recommendations varied by instrument.

Conclusions:

All 3 instruments demonstrated consistent findings when estimating associations with %BF, but were different for prevalence estimates. Researchers must carefully consider the intended use of PA data when choosing a measurement instrument.

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Olivier Caron, Thierry Gélat, Patrice Rougier and Jean-Pierre Blanchi

The center of foot pressure (CP) motions, representing the net neuromuscular control, was compared to the center of gravity (CG) motions, representing the net performance. The comparison focused on the trajectory path length parameter along the mediolateral and antero-posterior axes because these two variables depend on amplitude versus frequency relationship. This relationship was used to evaluate the CG motions based on the CP motions. Seven subjects stood still on a force plate with eyes open and eyes closed. The results showed that the ratio of (CP – CG)/CP trajectory path length was personal for each subject. These results suggest different levels of passive (ligaments, elastic properties) and active (reflex activity) stiffness. For some subjects, this ratio was significantly lower for the eyes open condition than for the eyes closed condition, indicating a decrease of the active stiffness for the eyes open condition. Therefore, a CG – CP comparative analysis appeared helpful in understanding the control of balance and necessary to quantify the subjects’ net performance.