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.
Jane E. Yardley, Jacqueline Hay, Freya MacMillan, Kristy Wittmeier, Brandy Wicklow, Andrea MacIntosh and Jonathan McGavock
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.
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.
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.
Raymonde E. Jean, Manideep Duttuluri, Charlisa D. Gibson, Sadaf Mir, Katherine Fuhrmann, Edward Eden and Azhar Supariwala
Exercise improves sleep quality, yet people with untreated obstructive sleep apnea (OSA) may engage in less physical activity (PA) due to fatigue and daytime sleepiness. We examined changes in PA and sleep quality before and after treatment with continuous positive airway pressure (CPAP) in OSA patients.
In this prospective longitudinal study, persons with a primary diagnosis of OSA were enrolled at a community-based hospital in New York City. At 3 time intervals pre- and post-CPAP (3–8 months), we measured sleep quality using validated questionnaires, perceived PA using the International Physical Activity Questionnaire (IPAQ), and actual PA using pedometer steps per day. We sought to investigate how CPAP use and changes in sleep quality impacted the number of steps taken, as recorded in pedometer steps.
In total, 62 patients were enrolled in the study from March 2012 to July 2014. In all, patients averaged 53 years of age, and 26 patients (42%) were female. Among all participants, 86% of persons had moderate to severe sleep apnea (AHI ≥15). Approximately 73% of participants were compliant with CPAP use. Poor sleep quality correlated with lower actual PA (P = .004) at baseline. At 3 and 7 months, there was significant improvement in sleep quality (Δ –2.63 ± 3.4 and Δ –3.5 ± 3.8; P < .001) and actual PA (Δ 840 ± 1313 and Δ 1431 ± 1419 steps/day, P < .001) compared with baseline. On multivariate analyses, participants with a higher waist circumference had a significantly greater increase in actual PA (P = .018).
Treatment of OSA with CPAP had a progressive incremental improvement in sleep quality and actual PA.
Ksenia I. Ustinova, Valery M. Goussev, Ramesh Balasubramaniam and Mindy F. Levin
To determine how arm movements influence postural sway in the upright position after stroke, interactions between arm, trunk, and center of pressure (CoP) displacements in the sagittal direction were investigated in participants with hemiparesis and healthy subjects. Participants swung both arms sagittally in either of 2 directions (in-phase, anti-phase) and at 2 speeds (preferred, fast) while standing on separate force plates. Variables measured included amplitude and frequency of arm swinging, shoulder and trunk range of motion, CoP displacements under each foot and of the whole body, and the relationships between the arm, trunk, and CoP displacements. CoP displacements under the non-paretic leg were greater than those under the paretic leg, which may in part be related to the larger amplitude of swinging of the non-paretic arm. CoP displacements under each foot were not related to arm swinging during in-phase swinging at the preferred speed in healthy subjects. When speed of arm swinging was increased, however, the CoP moved in a direction opposite to the arm movement. In contrast, in individuals with hemiparesis, CoPs and arms moved in the same direction for both speeds. During anti-phase swinging in healthy subjects, the trunk counterbalanced the arm movements, while in participants with hemiparesis, the trunk moved with the affected arm. Results show that stroke resulted in abnormal patterns of arm-trunk-CoP interactions that may be related to a greater involvement of the trunk in arm transport, an altered pattern of coordination between arm and CoP displacements, and an impaired ability of the damaged nervous system to adapt postural synergies to changes in movement velocity.
Carolyn A. Duncan, Scott N. MacKinnon and Wayne J. Albert
The purpose of this study was to examine how wave-induced platform motion effects postural stability when handling loads. Twelve participants (9 male, 3 female) performed a sagittal lifting/lowering task with a 10 kg load in different sea conditions off the coast of Halifax, Nova Scotia, Canada. Trunk kinematics and foot center of force were measured using the Lumbar Motion Monitor and F-Scan foot pressure system respectively. During motion conditions, significant decreases in trunk velocities were accompanied by significant increases in individual foot center of pressure velocities. These results suggest that during lifting and lowering loads in moving environments, the reaction to the wave-induced postural disturbance is accompanied by a decrease in performance speed so that the task can be performed more cautiously to optimize stability.
Nadav Goldschmied, Max Nankin and Guy Cafri
Icing is a common strategy used in American football during the last moments of a close game when a coach may ask for a time-out to allow an opposing kicker, who is about to attempt a decisive field-kick, an extended period of time possibly to contemplate the negative outcomes if he fails to score (i.e., rumination). Using archival data of pressure kicks from six consecutive National Football League seasons (2002—2008), a mixed-effects hierarchical linear model was applied. It was found that icing was successful in reducing scoring while other environmental factors such as experience, game location or game score were not associated with conversion success. In a secondary analysis it was demonstrated that if a time-out before the pressure kick is requested by the coaches of the kicking team, kickers are not subjected to the debilitating effects of icing. Theoretical and applied implications are also discussed.
Brian L. Davis, Julie E. Perry, Donald C. Neth and Kevin C. Waters
A device has been designed to simultaneously measure the vertical pressure and the anterior-posterior and medial-lateral distributed shearing forces under the plantar surface of the foot. The device uses strain gauge technology and consists of 16 individual transducers (each with a surface area measuring 2.5 × 2.5 cm) arranged in a 4 × 4 array. The sampling frequency is 37 Hz and data may be collected for 2 s. The device was calibrated under both static and dynamic conditions and revealed excellent linearity (±5%), minimal hysteresis (±7.5%), and very good agreement between applied and measured loads (±5%). Vector addition of the distributed loads gave resultant forces that were qualitatively very similar to those obtained from a standard force plate. Data are presented for measurements from the forefoot of 4 diabetic subjects during the initiation of gait, demonstrating that distributed shear and pressure on the sole of the foot can be measured simultaneously.