Prolonged (>30 min) unconstrained standing (PUS) was studied in 10 young healthy subjects. The usual methods of stabilographic analysis assume a random center of pressure (COP) migration. This study was based on the opposite idea and showed that during PUS, specific and consistent patterns of the COP migration can be recognized by a computer algorithm. Three COP migration patterns were found: (a) shifting, a fast displacement of the average position of COP from one region to another; (b) fidgeting, a fast and large displacement and returning of COP to approximately the same position; and (c) drifting, a slow continuous displacement of the average position of COP. A software code was written and default parameter values were chosen for recognizing COP migration patterns. For 30-min PUS the following patterns were identified: Shifting was generally observed every 316 ± 292 sec in the anterior-posterior (a-p) direction with an average shift amplitude of 17 ± 15 mm, and every 199 ± 148 sec in the medial-lateral (m-1) direction with an average shift amplitude of 22 ± 38 mm. Corresponding time intervals for fidgeting were 59 ± 15 sec in the a-p direction and 49±16 sec in the m-1 direction. The average drift-to-drift interval was 319 ± 173 sec in the a-p direction and 529 ± 333 sec in the m-1 direction.
Marcos Duarte and Valdimir M. Zatsiorsky
Scott W. Cheatham, Kyle R. Stull and Morey J. Kolber
without decreasing muscle performance, which may be ideal for a preexercise warm-up and postexercise cool down. 1 – 3 RM may help to attenuate decrements in muscle performance and delayed onset muscle soreness (DOMS). 1 – 3 RM may also increase posttreatment pressure pain thresholds (PPTs), 4 reduce
M. Adoración Villarroya, José Antonio Casajús and José María Pérez
To compare temporal and pressure values between racewalking and normal walking (freely selected speed) and evaluate the impact of racewalking on normal walking.
Design and Participants:
Temporal and plantar-pressure values were recorded (xPression system) during normal walking and racewalking in 8 high-level racewalkers. The Wilcoxon test was used for comparisons.
Duration of walking and racewalking cycle phases (seconds and percentage of the cycle), peak and average pressures under the hind foot and metatarsal heads, and pressure distribution (%) among metatarsal heads.
Results and Conclusions:
Normal walking: temporal parameters similar to those described in normal gait; peak pressures higher than those described in nonracewalkers with displacement toward lateral forefoot. Racewalking: shorter cycles (important decrease of midstance phase); higher peak pressures than during normal walking in the hind foot and 4th and 5th metatarsal heads; average pressures similar to normal walking in hind foot and lower in forefoot; pressure displacement toward lateral forefoot greater than in normal walking.
Anthony J. Lisi, Conor W. O’Neill, Derek P. Lindsey, Robert Cooperstein, Elaine Cooperstein and James F. Zucherman
This paper presents the first reported measurements of lumbar intervertebral disc pressure in vivo during spinal manipulation. A pressure transducer was inserted into the nucleus pulposus of one normal-appearing lumbar disc in an asymptomatic adult volunteer. Pressures were recorded during several body positions and maneuvers, then during spinal manipulation, and lastly during a repetition of the preintervention body positions. Baseline pressures in the prone and side-lying positions measured 110 kPa and 150 kPa, respectively. During the manipulation, pressure rose to a peak of 890 kPa over 250 ms. Immediately following, pressures in the prone and side-lying positions measured 150 kPa and 165 kPa, respectively. These data do not support the hypotheses that manipulation can reduce a herniation by decreasing intradiscal pressure, or cause a herniation by raising pressure to failure levels. Further work may lead to a better understanding of this treatment method.
Martina Navarro, Nelson Miyamoto, John van der Kamp, Edgard Morya, Ronald Ranvaud and Geert J.P. Savelsbergh
We investigated the effects of high pressure on the point of no return or the minimum time required for a kicker to respond to the goalkeeper’s dive in a simulated penalty kick task. The goalkeeper moved to one side with different times available for the participants to direct the ball to the opposite side in low-pressure (acoustically isolated laboratory) and high-pressure situations (with a participative audience). One group of participants showed a significant lengthening of the point of no return under high pressure. With less time available, performance was at chance level. Unexpectedly, in a second group of participants, high pressure caused a qualitative change in which for short times available participants were inclined to aim in the direction of the goalkeeper’s move. The distinct effects of high pressure are discussed within attentional control theory to reflect a decreasing efficiency of the goal-driven attentional system, slowing down performance, and a decreasing effectiveness in inhibiting stimulus-driven behavior.
Ken Hodge and Wayne Smith
This case study focused on pressure, stereotype threat, choking, and the coping experiences of the New Zealand All Blacks rugby team during the period from 2004-2011 leading into their success at the 2011 Rugby World Cup (RWC). Employing a narrative approach this case study examined public expectation, pressure, and coach-led coping strategies designed to “avoid the choke” by the All Blacks team. An in-depth interview was completed with one of the All Blacks’ coaches and analyzed via collaborative thematic analysis (Riessman, 2008). In addition multiple secondary data sources (e.g., coach & player autobiographies; media interviews) were analyzed via holistic-content analysis (Lieblich et al., 1998). Collectively these analyses revealed five key themes: public expectation and pressure, learning from 2007 RWC, coping with RWC pressure, decision-making under pressure, and avoiding the choke. Practical recommendations are offered for team sport coaches with respect to coping with pressure and avoiding choking.
Juan C. Chicote, Juan V. Durá, Juan M. Belda and Rakel Poveda
Principal component analysis and functional regression are combined in a model to analyze a time series of pressure maps. The model is tested measuring the pressures over a chair seat while a subject performs a combination of simple movements. A sampling rate of 3 Hz is adequate for applying the model in sitting postures. The model is able to detect patterns of movement over time, although more variables are necessary if the movements produce similar pressure distributions.
Column-editor : Martin A. Fees
Karen L. Nau, Victor L. Katch, Robert H. Beekman and Macdonald Dick II
Intraarterial blood pressure (BP) response to bench press weight lifting (WL) was evaluated in 11 children. Aortic systolic and diastolic pressures and heart rate (HR) were measured during WL. Baseline systolic and diastolic pressures were 120 and 81 mmHg, and HR was 86 bpm. Subjects lifted to voluntary fatigue weights equaling 60, 75, 90, and 100% of their predetermined one-repetition maximum (1RM). For each weight lifting condition, BP and HR increased as more repetitions were completed. Peak systolic pressure was 168, 177, 166, and 162 mmHg, peak diastolic pressure was 125, 139, 133, and 130 mmHg, and peak heart rate was 142, 148, 142, and 139 bpm at 60, 75, 90, and 100% 1RM, respectively. Peak BP and HR were greater during WL than rest but did not differ between conditions. The relative BP response to WL in children was similar to adult values. For all conditions, pressures increased as more repetitions were completed. It was concluded that peak pressures occur at voluntary fatigue, independent of the combination of resistance and repetitions used to achieve fatigue.
Sandra K. Knecht, Wayne A. Mays, Yvette M. Gerdes, Randal P. Claytor and Timothy K. Knilans
The aim of this study was to provide a normal reference for arm–leg blood pressure gradients in normal pediatric and young-adult patients before and after exercise. We assessed 216 normal participants by physical or echocardiographic exam, maximally tested using the James Cycle Protocol, with arm and leg blood pressures taken pre- and postexercise. Arm–leg gradients significantly increased from –5 mmHg at rest to 4, 2, and 1 mmHg 1, 3, and 4 min postexercise (p < .05). There was a small, statistically significant increase in arm-leg blood pressure with exercise, which is probably clinically insignificant. These data serve as a normal reference.