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.
Hélène Perrault, Maria Tzovanis, Dominique Johnson, André Davignon, Claude Chartrand, Abdelkader Mokrane and Réginald A. Nadeau
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
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.
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.
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.
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.
Jane E. Yardley, Jacqueline Hay, Freya MacMillan, Kristy Wittmeier, Brandy Wicklow, Andrea MacIntosh and Jonathan McGavock
Type 2 diabetes is associated with hypertension and an increased risk of cardiovascular disease. In adults, blood pressure (BP) responses to exercise are predictive of these complications. To determine if the hemodynamic response to exercise is exaggerated in youth with dysglycemia (DG) compared with normoglycemic overweight/obese (OB) and healthy weight (HW) controls a cross-sectional comparison of BP and heart rate (HR) responses to graded exercise to exhaustion in participants was performed. DG and OB youth were matched for age, BMI z-score, height and sex. Systolic (SBP) and diastolic BP (DBP) were measured every 2 min, and HR was measured every 1 min. SBP was higher in OB and DG compared with HW youth at rest (p > .001). Despite working at lower relative workloads compared with HW, the BP response was elevated during exercise in OB and DG. For similar HR and oxygen consumption rates, BP responses to exercise were slightly higher in OB and DG compared with HW. OB and DG youth both display elevated resting and exercise BP relative to HW peers. Obesity may play a greater role than dysglycemia in the exaggerated BP response to exercise in youth.
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.
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.
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.
To examine the effects of LBNP on biochemical, pain, and performance parameters during a 5-d recovery period after a damaging plyometric-exercise bout.
Randomized controlled study.
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.
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.
LBNP therapy could improve recovery by limiting the loss in muscle strength and power and limiting the presence of pain.
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.
Joaquin U. Gonzales, Dustin M. Grinnell, Martha J. Kalasky and David N. Proctor
The authors examined interindividual and sex-specific variation in systolic (SBP) and diastolic (DBP) blood pressure responses to graded leg-extension exercise in healthy older (60–78 yr) women (n = 21) and men (n = 19). Maximal oxygen uptake (VO2max), body composition, physical activity (accelerometry), and vascular function were measured to identify predictors of exercise BP. Neither VO2max nor activity counts were associated with the rise in SBP or DBP during exercise in men. The strongest predictors of these responses in men were age (SBP: r 2 = .19, p = .05) and peak exercise leg vasodilation (DBP: r 2 = –.21, p < .05). In women, the modest relationship observed between VO2max and exercise BP was abolished after adjusting for central adiposity and activity counts (best predictors, cumulative r 2 = .53, p < .05, for both SBP and DBP). These results suggest that determinants of variation in submaximal exercise BP responses among older adults are sex specific, with daily physical activity influencing these responses in women but not men.
Erik Bijleveld and Harm Veling
To better understand the characteristics of athletes who tend to underperform under pressure, we investigated how (a) working memory (WM) capacity and (b) responsiveness of the dopamine system shape real-life performance under pressure. We expected that athletes with smaller WM capacity or a more responsive dopamine system (as operationalized with a risk-taking measure) are especially prone to fail during decisive moments. In a sample of competitive tennis players, WM capacity was measured with the Automated Operation Span task (AOSPAN); responsiveness of the dopamine system was measured with a risk-taking measure, the Balloon Analogue Risk Task (BART). As expected, higher AOSPAN scores predicted better performance during decisive sets; higher BART scores predicted worse performance during decisive sets. These findings indicate that real-life tennis performance can be predicted from behavioral tasks that tap into WM functioning and risk taking, and suggest that the ability to effectively use WM despite pressure separates chokers from nonchokers.
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.