The aim of this study was to investigate the effect of errors in the location of the center of pressure (5 and 10 mm) on lower limb joint moment uncertainties at different gait velocities (1.0, 1.5, and 2.0 m/s). Our hypotheses were that the absolute joint moment uncertainties would be gradually reduced from distal to proximal joints and from higher to lower velocities. Joint moments of five healthy young adults were calculated by inverse dynamics using the bottom-up approach, depending on which estimate the uncertainty propagated. Results indicated that there is a linear relationship between errors in center of pressure and joint moment uncertainties. The absolute moment peak uncertainties expressed on the anatomic reference frames decreased from distal to proximal joints, confirming our first hypothesis, except for the abduction moments. There was an increase in moment uncertainty (up to 0.04 N m/kg for the 10 mm error in the center of pressure) from the lower to higher gait velocity, confirming our second hypothesis, although, once again, not for hip or knee abduction. Finally, depending on the plane of movement and the joint, relative uncertainties experienced variation (between 5 and 31%), and the knee joint moments were the most affected.
Franklin Camargo-Junior, Marko Ackermann, Jefferson F. Loss and Isabel C.N. Sacco
Ann M. Swartz, Scott J. Strath, Sarah J. Parker and Nora E. Miller
The purpose of this study was to investigate the combined impact of obesity and physical activity (PA) on the health of older adults. Pedometer-determined steps/d, body-mass index (BMI), resting blood pressure, and fasting glucose (FG) were assessed in 137 older adults (69.0 ± 8.9 yr). The active group (>4,227 steps/d) had lower systolic blood pressure (SBP; p = .001), diastolic blood pressure (DBP; p = .028), and FG (p < .001) than the inactive group (≤4,227 steps/d). The normal-BMI group (18.5-24.9 kg/m2) had lower SBP (p < .001) and DBP (p = .01) than the obese group (≤30 kg/m2). There were no differences in SBP (p = .963) or DBP (p = 1.0) between active obese and inactive normal-BMI groups. The active obese group, however, had a more favorable FG than the inactive normal-BMI group (χ2 = 18.9, df = 3, p = .001). Efforts to increase PA of older adults should receive the same priority as reducing obesity to improve BP and FG levels.
Yun Wang and Kazuhiko Watanabe
The notion of limb dominance has been commonly used in the upper extremity, yet the two lower extremities are often treated as equal for analytical purposes. Attempts to determine the effects of limb laterality on gait have produced conflicting results. The purpose of this study was to determine if limb dominance affects the vertical ground reaction force and center of pressure (COP) during able-bodied gait. The Parotec system (Paromed GmbH, Germany) was used to collect plantar foot pressure data. Fifteen subjects volunteered to participate in this study. The coefficient of variation of the COP displacement in the mediolateral direction and the variability of peak force beneath the lateral forefoot in the nondominant foot were significant greater than in the dominant foot. Moreover, COP velocity in the anterior-posterior direction during the terminal stance phase showed greater value in the dominant foot. Our study provides support for limb laterality by showing limb dominance affected the vertical ground reaction force and center of pressure during walking gait. This finding suggests it is an important issue in movement science for clinicians and would assist in improving sports performance and rehabilitation program.
, 2012 ). The role of the gymnastics coach should be to create an appropriate motivational climate and reduce any anxiety gymnasts might be experiencing ( White & Bennie, 2015 ). However, based on the phone call with C.S.’s father, it seemed that both he and the coach were putting pressure on C.S. to
John Pates and Kieran Kingston
. Typically, I would have players playing in the morning “draw” and afternoon draw, and the draw for the tournament tee times would change from day to day. This meant that my daily routine would have to change accordingly. This often creates additional pressures for both the athlete and the consultant and
Christoph Dehner, Andreas Schmelz, Hans-Ullrich Völker, Jochen Pressmar, Martin Elbel and Michael Kramer
Chronic low back pain (LBP) has been reported with a high incidence in elite rowers. It results in less effective training, long interruptions in training, and a drop in performance.
The authors hypothesized that exercise-induced LBP in rowers is caused by a chronic functional compartment syndrome (CFCS) of the multifidus muscle.
Controlled clinical trial.
The rowers were tested in their training camp. The control group was tested at a university hospital.
14 volunteer elite rowers complaining of LBP and 16 healthy volunteer amateur athletes.
Main Outcome Measurements:
Intramuscular pressure (IMP), tissue oxygenation pressure (pO2), and median frequency (MF) shift in the electromyographic power density spectrum during isometric fatiguing extension at 60% of maximum voluntary contraction.
At the beginning (controls 186.6 mm Hg vs rowers 60.2 mm Hg, P = .002) and the end (controls 224.1 mm HG vs rowers 77.1 mm Hg, P < .001) of the endurance exercise the median IMP was significantly higher in the healthy controls. Nearly identical resting pO2 was measured in both groups (controls 37.6 mm Hg vs rowers 37.3 mm Hg, P = .740). Rowers showed higher median MF shift (rowers −11.5 Hz vs controls −8.5 Hz, P = .079) during contraction.
These observations cannot sufficiently be explained by the CFCS model and suggest that factors other than IMP have an additional effect on pain generation during exercise in elite rowers.
Liana Tennant, David Kingston, Helen Chong and Stacey Acker
Occupational kneeling is associated with an increased risk for the development of knee osteoarthritis. Previous work studying occupational kneeling has neglected to account for the fact that in many industrial settings, workers are required to wear steeltoe work boots. Thus, the purpose of this study was to evaluate the effect of work boot wear on the center of pressure location of the ground reaction force, knee joint angle, and magnitude of the ground reaction force in a kneeling posture. Fifteen healthy males were fit with 3D motion capture markers and knelt statically over a force plate embedded in the floor. Using the tibial tuberosity as the point of reference, the center of pressure in shod condition was shifted significantly medially (on average 0.009 m [P = .005]) compared with the barefoot condition. The knee was significantly less internally rotated (shod: –12.5° vs. barefoot: –17.4° [P = .009]) and the anterior/posterior shear force was significantly greater in the shod condition (shod: 6.0% body weight vs. barefoot: 1.5% body weight [P = .002]). Therefore, wearing work boots alters the kneeling posture compared with barefoot kneeling, potentially loading different surfaces of the knee, as well as altering knee joint moments.
Diego Augusto Santos Silva, Mark Tremblay, Andreia Pelegrini, Roberto Jeronimo dos Santos Silva, Antonio Cesar Cabral de Oliveira and Edio Luiz Petroski
Criterion-referenced cut-points for health-related fitness measures are lacking. This study aimed to determine the associations between aerobic fitness and high blood pressure levels (HBP) to determine the cut-points that best predict HBP among adolescents.
This cross-sectional school-based study with sample of 875 adolescents aged 14–19 years was conducted in southern Brazil. Aerobic fitness was assessed using the modified Canadian Aerobic Fitness Test (mCAFT). Systolic and diastolic blood pressure were measured by the oscillometric method with a digital sphygmomanometer. Analyses controlled for sociodemographic variables, physical activity, body mass and biological maturation.
Receiver Operating Characteristic (ROC) curves demonstrated that mCAFT measures could discriminate HBP in both sexes (female: AUC = 0.70; male: AUC = 0.63). The cut-points with the best discriminatory power for HBP were 32 mL·kg-1·min-1 for females and 40 mL·kg-1·min-1 for males. Females (OR = 8.4; 95% CI: 2.1, 33.7) and males (OR: 2.5; CI 95%: 1.2, 5.2) with low aerobic fitness levels were more likely to have HBP.
mCAFT measures are inversely associated with BP and cut-points from ROC analyses have good discriminatory power for HBP.
Daniel J. Brown, Rachel Arnold, Martyn Standage and David Fletcher
century. Early descriptions of thriving in sport emerged from conceptual investigations on mental toughness in elite athletes (see Bull, Shambrook, James, & Brooks, 2005 ; Jones, Hanton, & Connaughton, 2002 ). Within these studies, thriving on the pressure of competition was described as a key attribute
Kathleen F. Janz and Larry T. Mahoney
To assess the relationship of changes in physical fitness and body composition to heart growth and rising blood pressure (BP) during early puberty, fat-free mass (FFM), body fatness (% fat), physical fitness (peak VO2, peak mechanical power, peak O2 pulse, peak systolic blood pressure [SBP], and grip strength), Tanner stage, resting BP, and echocardiographic left ventricular mass (LVM) were measured in 123 children (age M = 10 years) and remeasured 2 years later. Increased FFM, increased grip strength, and increased peak power explained 28% of the variability in heart growth. Increased FFM, increased % fat, and decreased peak O2 pulse explained 23% of the variability in rising SBP. During puberty, physical fitness is an independent predictor of changing heart size and systolic blood pressure. Results suggest that improvements in physical fitness and decreases in body fatness may have beneficial effects on children’s blood pressure.