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W. Jack Rejeski, Karen M. Neal, Martine E. Wurst, Peter H. Brubaker and Walter H. Ettinger Jr.

An elderly patient population was used to investigate whether an acute bout of aerobic exercise (AE) would reduce systolic blood pressure (SBP) to a greater extent than would a bout of weight lifting (WL). SBPs were studied in the context of a laboratory Stressor as well as during activities of daily living using ambulatory monitoring devices (AMBPs). Patients participated in a laboratory Stressor and were monitored via AMBP for 8 hr. SBPs were lower for up to 5 hr postexercise for the AE treatment only. In addition, in comparison to no-exercise control data, baseline SBP was lower for the AE group than the WL group prior to the Stressor. Subjects in the AE condition also tended to have lower SBP responses following exercise than patients in the WL group, although these differences did not reach a conventional level of statistical significance. These data provide evidence that single bouts of AE, but not WL, may lower SBP in elderly patients, even for those who have compromised function due to osteoarthritis of the knee.

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Cyril Burdet and Patrice Rougier

To question the relation between uni- and bipedal postural skills, 21 subjects were required to stand on a force platform through uni- and bipedal conditions. These two protocols are commonly used paradigms to assess the balance capacities of healthy and disabled patients. The recorded displacements of the center of pressure (CP) were decomposed along mediolateral and anteroposterior axes and assessed through variance positions and parameters obtained from fractional Brownian motion (fBm) modeling to determine the nature and the spatiotemporal organization of the successive controlling mechanisms. The variances underline the relative independence of the two tasks. Nevertheless, as highlighted by the fBm framework, postural correction is initiated for the unipedal stance after shorter time delays and longer covered distances. When compared to bipedal standing, one of the main characteristics of unipedal standing is to induce better-controlled CP trajectories, as deduced from the scaling regimes computed from the fBm modeling. Lastly, the control of the CP trajectories during the shortest time intervals along the anteroposterior axis appears identical for both uni- and bipedal conditions. Unipedal and bipedal standing controls should thus be viewed as two complementary tasks, each providing specific and complementary insights into the postural control organization.

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Hélène Perrault, Maria Tzovanis, Dominique Johnson, André Davignon, Claude Chartrand, Abdelkader Mokrane and Réginald A. Nadeau

This study compares the autonomic responses of 9 adolescents (mean ± SEM: 17±1 years) successfully operated for tetralogy of Fallot (TOF) in early childhood and 8 age-matched healthy controls (CTRL) using R-R and blood pressure variability. Continuous ECG and BP recordings were obtained during spontaneous and controlled respiration (CR) at 0.20 Hz as well as after an 85° head-up tilt (HUT) and during steady-state cycling at heart rates of 100 and 120 bpm, selected to reflect partial and complete cardiac vagal withdrawal. TOF exhibited total R-R variance and HF power (ms2) lower than CTRL under both spontaneous (938 ± 322 vs. 1,714 ± 296) and CR (1,541 ± 527 vs. 4,725 ± 1,207; p < .05), which may be indicative of a lower cardiac vagal activity. HUT decreased the R-R HF component, which remained lower in TOF than CTRL and increased the diastolic BP LF component in TOF but not in CTRL. Exercise decreased the R-R HF power more in TOF than CTRL. The exaggerated diastolic BP and limited heart rate responses to tilting and the more marked vagal withdrawal at Ex120 in TOF may be suggestive of a disturbance in the cardiac sympathetic response. Further studies are needed to confirm these observations on larger groups of young adults successfully operated for TOF.

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Rodolfo B. Parreira, Marcela C. Boer, Lucas Rabello, Viviane de Souza P. Costa, Eros de Oliveira Jr. and Rubens A. da Silva

The aim of this study was to evaluate the changes in center of pressure (COP) movement in four time intervals (5, 10, 15 and 30 s) during a one-leg stance test performed by young and elderly adults. Twelve young adults (mean 20 years) and 12 elderly subjects (mean 68 years) participated in this study. The subjects performed three 30 s trials of an eyes open one-leg stance test on a force platform, in which the COP parameter was computed at four points in time from same original COP signal. Significant differences were found between the young and elderly adults (P < .007) only at the 10, 15 and 30 s intervals. For both groups, COP changes were significantly different between the 5 s time interval and other intervals (10, 15 and 30 s). In conclusion, these results pointed out that age-related difference in COP changes were time dependent. This suggests that the use of longer durations increases the possibility of distinguishing more subtle differences in postural strategy among different groups of subjects.

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Jonathan Sinclair, Sarah J. Hobbs, Paul J. Taylor, Graham Currigan and Andrew Greenhalgh

In running analyses where both kinetic and kinematic information is recorded, participants are required to make foot contact with a force and/or pressure measuring transducer. Problems arise if participants modify their gait patterns to ensure contact with the device. There is currently a paucity of research investigating the influence of different underfoot kinetic measuring devices on 3-dimensional kinematics of running. Fifteen participants ran at 4.0 m/s in four different conditions: over a floor embedded force plate, Footscan, Matscan, and with no device. Three-dimensional angular kinematic parameters were collected using an eight camera motion analysis system. Hip, knee, and ankle joint kinematics were contrasted using repeated-measures ANOVAs. Participants also rated their subjective comfort in striking each of the three force measuring devices. Significant differences from the uninhibited condition were observed using the Footscan and Matscan in all three planes of rotation, whereas participants subjectively rated the force plate significantly more comfortable than either the Footscan/Matscan devices. The findings of the current investigation therefore suggest that the disguised floor embedded force plate offers the most natural running condition. It is recommended that analyses using devices such as the Footscan/Matscan mats overlying the laboratory surface during running should be interpreted with caution.

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Brad Hodgson, Laurie Tis, Steven Cobb, Shawn McCarthy and Elizabeth Higbie

Context:

Because of research variability and the increasing use of orthotics to manage lower extremity problems, further research is warranted.

Objective:

To investigate the effect of rear-foot- and forefoot-posted (PAL) and mediolongitu-dinal arch-supported (SOLE) orthotics on plantar pressure (PP) during walking.

Design:

Repeated measures.

Setting:

Laboratory.

Participants:

17 subjects with forefoot varus.

Intervention:

Data were collected at 0 and 6 weeks for no-orthotic and orthotic conditions.

Measurements:

PPs were collected with the EMED Pedar measurement system.

Results:

Zero weeks: PAL increased PP in lateral forefoot (LFF), middle toes (MT), and lateral toes (LT) and decreased PP in lateral heel (LH), medial forefoot (MFF), and central forefoot (CFF). SOLE increased PP for midfoot (MF) and LT and decreased PP in medial heel (MH), LH, and CFF. 6 weeks: PAL increased PP in LFF, MT, and LT and decreased PP in LH, MFF, and CFF. SOLE increased PP in MF and decreased PP in MH, LH, and LFF.

Conclusion:

The SOLE orthotic appeared to be more effective in attaining the goals of custom-molded-orthotic intervention.

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Borut Fonda and Nejc Sarabon

It has been reported in practice that the application of lower-body negative pressure (LBNP) to elite athletes during periods of intense training can help aid recovery.

Purpose:

To examine the effects of LBNP on biochemical, pain, and performance parameters during a 5-d recovery period after a damaging plyometric-exercise bout.

Design:

Randomized controlled study.

Methods:

24 healthy young female adults were randomly allocated into 2 groups. Before and 1, 24, 48, and 96 h after the damaging exercise for hamstrings (50 drop jumps and 50 leg curls), participants underwent a series of tests (blood samples, pain sensation, countermovement jump, maximal isometric torque production, maximal explosive isometric torque production, and 10-m sprint). After the damaging exercise, the experimental group was exposed to intermittent LBNP therapy daily for 60 min.

Results:

There was a statistically significant interaction (P < .05) between the experimental and control groups for maximal strength, explosive strength, pain sensation, and vertical jumps (maximal power and force). No statistically significant interaction was present for the biochemical markers, jump height, and 100-m sprint.

Conclusions:

LBNP therapy could improve recovery by limiting the loss in muscle strength and power and limiting the presence of pain.

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Pedro C. Hallal, Samuel Carvalho Dumith, Felipe Fossati Reichert, Ana M.B. Menezes, Cora L. Araújo, Jonathan C.K. Wells, Ulf Ekelund and Cesar G. Victora

Objectives:

To explore cross-sectional and longitudinal associations between self-reported and accelerometry-based physical activity (PA) and blood pressure (BP) between 11 and 14 years of age.

Methods:

Prospective birth cohort study in Pelotas, Brazil. Participants were 427 cohort members who were followed up with at 11, 12, and 14 years of age, and had questionnaire data on PA and BP at 11 and 14 years, as well as accelerometry and questionnaire data on PA at 12 years. Outcome measures were continuous systolic and diastolic BP at 14 years, and change in BP from 11 to 14 years.

Results:

PA was unrelated to systolic BP in any analyses. PA measured by accelerometry at 12 years, but not questionnaire-derived PA, was inversely associated with diastolic BP at 14 years of age in fully adjusted models. Those who exceeded the 300-minutes PA threshold at all 3 visits had a 2.6 mmHg lower mean increase in DBP from 11 to 14 years compared with those classified below the threshold in all visits.

Conclusions:

Accelerometry-based PA was longitudinally inversely associated with diastolic BP. This finding was not evident when analyzing self-reported PA at a given age, suggesting a possible underestimation of the association when using subjective data.

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James L. Croft, Vinzenz von Tscharner and Ronald F. Zernicke

Compliant surfaces are used to challenge postural stability, but assessments are frequently limited to summary measures of center of pressure that do not provide insights into the temporal dynamics of motor coordination. Here, we measured center-of-pressure changes on three surfaces (solid, foam, and air-filled disc) and quantified the relative timing of changes in joint angles and muscle activity with respect to center-of-pressure changes. Nine active male subjects (20–30 years old) performed ten 30-s trials of unipedal stance on each of the three surfaces. Sway range, mean sway, mean sway velocity, path length, and fitted ellipse area increased, monotonically, from solid surface to foam to air-filled disc. The number of significant cross-correlations was greater for the compliant surfaces compared with the solid surface. Muscle activity preceded changes in center-of-pressure displacement, with the type of surface affecting the magnitude of the lead in the mediolateral direction. Center of pressure was more constrained on less stable surfaces and in the mediolateral direction.

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Ashley Coker-Cranney and Justine J. Reel

When athletes “uncritically accept” the coaching expectations associated with their sport, negative health consequences (e.g., disordered eating behaviors, clinical eating disorders) may result. The coach’s influence on disordered eating behaviors may be a product of factors related to overconformity to the sport ethic, issues with coach communication regarding recommendations for weight management, and the strength of the coach-athlete relationship. The present study investigated perceived weight-related coach pressure, the coach-athlete relationship, and disordered eating behaviors by surveying 248 female varsity athletes and dancers from four universities. Mediational analysis revealed that the coach-athlete relationship was a partial mediating variable between perceived coach pressures and disordered eating behaviors. Subsequently, strong relationships between coaches and their athletes may reduce the negative impact of perceived weight-related coach pressure on the development or exacerbation of disordered eating behaviors in female collegiate athletes.