SEARCH · PubMed Health

Results for “Power”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources

PubMed2004

A simulation study concerning the effect of varying the residual phenotypic correlation on the power of bivariate quantitative trait loci linkage analysis.

The power of bivariate variance components (VC) linkage analysis is affected by the size and source of the phenotypic correlation between variables. In particular, several authors have suggested that the power to detect linkage is greatest when the quantitative trait locus (QTL) and residual sources of variation induce phenotypic covariation in opposite directions, and that this increase in power is greatest when unique environmental sources of variation induce covariation in the direction opposite to the QTL. The purpose of the present study was to investigate further the effect of varying the residual correlation between variables on the power to detect linkage in a bivariate variance components linkage analysis. Data were simulated for a biallelic QTL that pleiotropically influenced two variables. The power to detect linkage was calculated under a variety of situations in which the proportion of phenotypic covariance resulting from shared sources of variation and from unique sources of variation was varied. These simulations were performed for the case in which the QTL affected the two variables equally and also for the case in which the QTL made unequal contributions to each variable. Our results confirm that the power to detect QTLs in a bivariate test for linkage depends upon the size and source of the residual correlation between variables, being greatest when the QTL and unique environmental sources of variation induce phenotypic covariation in opposite directions. We also found that when the QTL affected the two variables unequally, the power to detect linkage increased markedly as the correlation between unique environmental sources of variation increased from 0.6 to 0.9. Similar results were obtained under a variety of genetic models, including when there were unequal allele frequencies and dominance at the QTL. We suggest that a promising strategy to increase the power to detect QTLs might be to collect data from variables where there is either good observational evidence (e.g., from multivariate structural equation modeling of twin data) or a sound theoretical argument that the QTL and environmental factors induce covariation in opposite directions.

Alleles↗

PubMed2000

Stability of graft refractive power after penetrating keratoplasty.

PURPOSE: Patients needing penetrating keratoplasty (PK) and cataract extraction with intraocular lens (IOL) implantation may be handled with a single triple procedure or a two-stage procedure with initial keratoplasty and cataract surgery in a later session. The latter approach is considered more safe by some surgeons and allows adjustment of the IOL power to the power of the actual corneal graft. The purpose of this study was to estimate the optimal timing of cataract surgery with IOL implantation by studying the refractive stability of 8 mm penetrating keratoplasty grafts. METHODS: Penetrating keratoplasty (8.0 mm graft and recipient bed) was performed in 28 eyes of 28 patients. Corneal topography (TMS-1) was studied at 1, 2, 3, 6, and 12 months after surgery and after suture removal (30 months). The central spherical equivalent graft power was computed from the topographical data (rings 2 through 4). RESULTS: On average, the spherical equivalent graft power was stable from one month after surgery up to suture removal (range: 41.9 to 42.7 diopters). After suture removal the graft steepened slightly (0.7 diopters). Corneal refractive power of single grafts fluctuated considerably over time. The standard deviation on time-dependent changes in graft power was from 3 months efter PK smaller than the standard deviation on the graft powers at 12 months. CONCLUSION: The average central spherical equivalent power of an 8.0 mm donor graft in an 8.0 mm recipient bed was stable from one month after penetrating keratoplasty until suture removal. A two-stage procedure with cataract surgery performed 3 months after PK can, compared to the triple procedure, reduce postoperative ametropia at 12 months if graft topography is taken into consideration at the time of cataract surgery. We recommend that cataract surgery with IOL implantation takes place from 3 months after penetrating keratoplasty.

Adult↗

PubMed2001

Efficacy of manual and powered toothbrushes (I). Effect on clinical parameters.

BACKGROUND/AIM: The purpose of the present investigation was to compare manual (Crest Complete) and powered toothbrushing (Braun Oral-B 3D Plaque Remover) for their ability to affect clinical parameters of periodontal diseases. METHODS: 48 periodontal maintenance subjects completed this single-blind 6-month longitudinal study. Subjects had a minimum of 20 natural teeth excluding third molars and >10% of sites (approximately 17 sites) with pocket depth > or =4 mm and/or >10% sites with attachment level >4 mm. At baseline, subjects received full mouth clinical measurements (168 sites) to determine mean Plaque Index, Gingival Index, pocket depth and attachment level and % of sites exhibiting BOP. Subjects were then randomly assigned to one of two groups. The control group (N=26) used a manual toothbrush while the test group (N=22) used a powered toothbrush. Subjects received instruction in oral hygiene and used their assigned toothbrush twice daily according to instruction. Follow-up clinical assessments were performed at 3 and 6 months. Significance of differences in clinical measures over time was determined using the Quade test and between brushing groups at each time point using the Mann-Whitney test. RESULTS: Mean pocket depth, mean plaque index and % of sites exhibiting BOP showed significant reductions from baseline to 3 and 6 months in both groups. Mean probing attachment level and mean Gingival Index were significantly reduced in the powered brushing group only. There was a significant positive correlation between plaque reduction and reduction in other clinical parameters in both brushing groups. The majority of subjects showed improvements in clinical parameters at 6 months, although a greater proportion of subjects in the powered group showed a reduction in Plaque Index (77% versus 65%) and in % sites exhibiting BOP (82% versus 69%). Mean pocket depth and mean attachment level showed significantly greater reductions between baseline and 6 months in lingual and mandibular areas in the powered group. CONCLUSIONS: Both manual and powered toothbrushes reduced pocket depth, plaque index and BOP. The powered toothbrush significantly reduced mean gingival index and probing attachment level. The greatest benefit of the powered brush was at mandibular and lingual surfaces.

Adult↗

PubMed2003

Comparative power curves in bird flight.

The relationship between mechanical power output and forward velocity in bird flight is controversial, bearing on the comparative physiology and ecology of locomotion. Applied to flying birds, aerodynamic theory predicts that mechanical power should vary as a function of forward velocity in a U-shaped curve. The only empirical test of this theory, using the black-billed magpie (Pica pica), suggests that the mechanical power curve is relatively flat over intermediate velocities. Here, by integrating in vivo measurements of pectoralis force and length change with quasi-steady aerodynamic models developed using data on wing and body movement, we present mechanical power curves for cockatiels (Nymphicus hollandicus) and ringed turtle-doves (Streptopelia risoria). In contrast to the curve reported for magpies, the power curve for cockatiels is acutely concave, whereas that for doves is intermediate in shape and shows higher mass-specific power output at most speeds. We also find that wing-beat frequency and mechanical power output do not necessarily share minima in flying birds. Thus, aspects of morphology, wing kinematics and overall style of flight can greatly affect the magnitude and shape of a species' power curve.

Animals↗

PubMed2006

A simple confocal fibre-optic laser method for intraocular lens power measurement.

PURPOSE: To develop novel confocal fibre-optic laser method (CFOLM) for accurate and objective measuring of the dioptric power of both positive and negative intraocular lenses (IOLs). METHODS: The CFOLM principle of operation is based on a simple apertureless single-mode fibre laser confocal design. The key element is a single-mode fibre coupler that serves simultaneously as a point light source (3-5 microm fibre diameter) used for the formation of a collimated Gaussian beam, and as a confocal point receiver that is highly sensitive to spatial displacements of the focused backreflectance laser emission. The basic CFOLM systems include IOL testing set-ups for the measurement of both positive and negative IOLs. RESULTS: The CFOLM designs provide high accuracy (<or=1 microm) in spatially locating the IOL focal point and in measuring the focal length in a broad range of both positive and negative powers including high-magnification IOLs with power greater than +/-20 D. We have tested various IOL samples with both positive (+5 to +30 D) and negative (-5 to -20 D) powers and we have obtained high levels of power testing repeatability estimated by a SD in the interval of 0.004-0.06/0.003-0.013 D and a relative error in the interval of 0.015-0.3/0.02-0.16%, for positive/negative IOLs, respectively. CONCLUSIONS: The presented IOL power testing method offers a simple, accurate, objective, quick, and relatively inexpensive approach for dioptric power measurement of positive and negative IOLs. It provides an independent source of IOL power measurement data and information for evaluating the effectiveness and safety of novel IOL products.

Diagnostic Techniques, Ophthalmological↗

PubMed2000

Isotonic dynamometry for the assessment of power and fatigue in the knee extensor muscles of females.

Impairments in muscle power production and recovery following short-duration intense activity could lead to decreased performance and risk of injury. We developed a power test for the knee extensor muscles using torque-velocity testing and moderate isotonic loads. Twenty-eight female volunteers performed three maximal efforts at each of four isotonic loads (27.1, 40.6, 54.2 and 67.8 N. m). If the calculated regression line for the torque-velocity data had an r2 >/= 0.95 (i.e. an acceptable test), maximal power (408 +/- 56 W) was computed from the data. Immediately after torque-velocity testing, the subjects repeated maximal effort knee extensions with 33.9 N. m for three bouts of 15 repetitions with 15 s of rest to produce muscle fatigue, defined as a decrease in power output during isotonic exercise. After a 4 min rest, the torque-velocity test was repeated and power calculated (345 +/- 48 W). For the group, the recovery of maximal power after the fatigue protocol was 85%. The extremes were represented by one subject who recovered only 70% of her maximal power and another who recovered completely (>98%). Physiological differences in muscle power following repeated exercise could have an impact on the outcome of therapeutic interventions for sports injuries, fatigue syndromes and occupational over-use conditions.

Adult↗

PubMed1999

Circadian variation of EEG power spectra in NREM and REM sleep in humans: dissociation from body temperature.

In humans, EEG power spectra in REM and NREM sleep, as well as characteristics of sleep spindles such as their duration, amplitude, frequency and incidence, vary with circadian phase. Recently it has been hypothesized that circadian variations in EEG spectra in humans are caused by variations in brain or body temperature and may not represent phenomena relevant to sleep regulatory processes. To test this directly, a further analysis of EEG power spectra - collected in a forced desynchrony protocol in which sleep episodes were scheduled to a 28-h period while the rhythms of body temperature and plasma melatonin were oscillating at their near 24-h period - was carried out. EEG power spectra were computed for NREM and REM sleep occurring between 90-120 and 270-300 degrees of the circadian melatonin rhythm, i.e. just after the clearance of melatonin from plasma in the 'morning' and just after the 'evening' increase in melatonin secretion. Average body temperatures during scheduled sleep at these two circadian phases were identical (36.72 degrees C). Despite identical body temperatures, the power spectra in NREM sleep were very different at these two circadian phases. EEG activity in the low frequency spindle range was significantly and markedly enhanced after the evening increase in plasma melatonin as compared to the morning phase. For REM sleep, significant differences in power spectra during these two circadian phases, in particular in the alpha range, were also observed. The results confirm that EEG power spectra in NREM and REM sleep vary with circadian phase, suggesting that the direct contribution of temperature to the circadian variation in EEG power spectra is absent or only minor, and are at variance with the hypothesis that circadian variations in EEG power spectra are caused by variations in temperature.

Body Temperature↗

PubMed2001

The efficacy of powered liposuction.

BACKGROUND: Powered liposuction is a relatively new innovation for more efficient removal of adipose tissue. OBJECTIVE: To evaluate the effectiveness of powered liposuction in removing adipose tissue when compared to traditional liposuction. METHODS: Four powered liposuction devices were evaluated in the power on mode vs. the power off. The fat extracted in each of these modes was measured in a mucous specimen trap. RESULTS: There was increased fat extraction in the powered mode for all instruments. The increased rate of fat extraction varied from 20 to 45% between instruments. the overall increased extraction in powered vs. nonpowered mode was 30%. CONCLUSION: The powered liposuction devices tested significantly increase the efficacy of subcutaneous fat removal during liposuction.

Abdomen↗

PubMed2001

Muscle power of the ankle flexors predicts functional performance in community-dwelling older women.

OBJECTIVES: To test the hypothesis that peak power of the ankle flexors is related to physical functioning in older women with functional limitations. DESIGN: A cross-sectional study. SETTING: University-based human physiology laboratory. PARTICIPANTS: Thirty-four older women (75.4 +/- 5.1 years, 67.8 +/- 11.3 kg, body mass index 27.4 +/- 4.5) with self-reported functional limitations. MEASUREMENTS: Plantarflexion (PF) and dorsiflexion (DF) peak power and isometric strength with physical performance (stair climb time, repeated chair rise time, maximal and habitual gait velocity) were determined. An isokinetic dynamometer was used to measure isometric strength, isokinetic peak torque and power of PF and DF at five angular velocities (30 degrees, 60 degrees, 90 degrees, 120 degrees, and 180 degrees.sec-1), and isometric strength. RESULTS: Peak torque for both PF and DF declined with increasing velocity of movement (PF: P <.0001; DF: P <.0001), whereas peak power increased with increasing velocity up to 120 degrees.sec-1. The strongest univariate associations were found between chair rise time and DF peak power (r = 0.50; P <.002), stair climb time and DF peak power (r = 0.49; P <.003), habitual gait velocity and PF isometric strength (r = 0.53; P <.001), and maximal gait and PF isometric strength (r = 0.47; P <.005). Multivariate regression analysis revealed that DF and PF peak power along with the physical functioning and general health scores from the Medical Outcomes Study Short Form were independent predictors of chair and stair climb performance. CONCLUSION: These data suggest that ankle muscle power together with self-reported measures of health and physical functioning are essential components of functional mobility in older women with functional limitations.

Activities of Daily Living↗

PubMed2001

Velocity training induces power-specific adaptations in highly functioning older adults.

OBJECTIVE: To test the efficacy of high-velocity training in healthy older persons. DESIGN: A 12-week randomized trial, with subjects blocked for gender and residence, comparing high-velocity resistance training with a self-paced walking program. SETTING: Retirement community. PARTICIPANTS: Forty-three volunteers over the age of 70 years. INTERVENTION: Power group: high-velocity leg exercises 3 times weekly with weekly increases in resistance combined with 45 minutes of moderate, nonresistance exercise weekly. Walking group: moderate intensity exercise 30 minutes daily, 6 days weekly. MAIN OUTCOME MEASURES: Variables measured included leg press peak power and leg extensor strength. Functional performance outcomes included: 6-minute walk distance, Short Physical Performance Battery, Physical Performance Test, and Medical Outcomes Study Short-Form Health Survey. RESULTS: Peak power improved 22% (p =.004) in the power group (3.7 +/- 1.0 W/kg to 4.5 +/- 1.4 W/kg) but did not change in the walking group (3.99 +/-.76 W/kg to 3.65 +/-.94 W/kg). Leg extensor power at resistance of 50%, 60%, and 70% of body weight increased 50%, 77%, and 141%, respectively, in the power group (p <.0001, repeated-measures analysis of variance). Strength improved 22% in the power-trained individuals and 12% in the walkers (p <.0001). Training did not improve functional task performance in either group. One subject developed a radiculopathy during training. CONCLUSIONS: Resistance training focusing on speed of movement improved leg power and maximal strength substantially, but did not improve functional performance in healthy high-functioning older volunteers.

Adaptation, Physiological↗

PubMed2000

The validity of power output recorded during exercise performance tests using a Kingcycle air-braked cycle ergometer when compared with an SRM powermeter.

This study assessed the validity of power output recorded using an air-braked cycle ergometer (Kingcycle) when compared with a power measuring crankset (SRM). For part one of the study thirteen physically active subjects completed a continuous incremental exercise test (OBLA), for part two of the study twelve trained cyclists completed two tests; a maximal aerobic power test (MAP) and a 16.1 km time-trial (16.1 km TT). The following were compared; the peak power output (PPO) recorded for 1 min during MAP, the average power output for the duration of the time-trial and power output recorded during each stage of OBLA. For all tests, power output recorded using Kingcycle was significantly higher than SRM (P < 0.001). Ratio limits of agreement between SRM and Kingcycle for OBLA showed a bias (P < 0.00) of 0.90 (95%CI = 0.90-0.91) with a random error of X or / 1.07, and for PPO and 16.1 km TT ratio limits of agreement were 0.90 (95%CI = 0.88-0.92) X or / 1.07 and 0.92 (95% CI = 0.90-0.94) X or / 1.07, respectively. These data revealed that the Kingcycle ergometry system did not provide a valid measure of power output when compared with SRM.

Adult↗

PubMed1997

Paced effort and all-out 30-second power tests.

The purpose of this study was to determine whether mean power output in 30 seconds was greater in a paced effort test or an all-out effort under optimal loading conditions. Nine male athletes volunteered to participate. All testing was done on a Monark cycle ergometer with continuous measurement of velocity and resistance. Power output was calculated (Resistance x Velocity) and corrected for acceleration of the flywheel. For each subject, optimal resistance for peak power output was determined with 5 brief (7-second) tests. Subsequently, 3 all-out 30-second tests using 80, 90 and 100% of this estimated optimal resistance, then 3 paced effort 30-second tests were completed on separate days. Pacing was accomplished with velocity feedback at 80, 100 or 120% of optimal velocity calculated from the all-out tests. Subjects were encouraged to try to exceed the target velocity if possible during the final 10 seconds of the paced effort test. The best all-out test (772 +/- 35 W) was not different (paired t test, p = 0.31) from the best paced effort test (787 +/- 27 W). Furthermore, there was no significant difference between mean power output in the all-out tests at 90% (736 +/- 28 W) and 100% (766 +/- 36 W) of estimated optimal resistance for peak power output (1.16 +/- 0.05 N x kg[-1]), but mean power at 80% of the estimated optimal resistance was lower (722 +/- 31 W; ANOVA for repeated measures, p < 0.05). In conclusion, a paced effort test does not permit greater mean power output over 30 seconds than an all-out test, and there is considerable latitude in apparent optimal resistance for mean power output in a 30-second test.

Analysis of Variance↗

PubMed1996

Effects of differing pedalling speeds on the power-duration relationship of high intensity cycle ergometry.

The aim of this experiment was to investigate the effects of differing pedalling speeds on the power-duration relationship during high intensity cycle ergometry with pedal cadences of 50 (low), 90 (intermediate) and 110 (high) r.min-1. This hyperbolic power-duration relationship can be described as: (P - phiPA).t = W', where P = power output, t = time to exhaustion, and phiPA and W' are constants. Eight volunteer male subjects, aged 24 +/- 2.6 yr, with no competitive cycling training took part in this study and each undertook thirteen tests on a Lode BV Excalibur Sport V1.52 cycle ergometer over an eight week period. The first exercise bout was a 30 W.min-1 incremental cycle at 50 r.min-1 to volitional fatigue. This allowed the identification of a range of power outputs that would be used to construct and examine the power-duration relationships for each subject at 50, 90 and 110 r.min-1. At both 50 and 90 r.min-1, power outputs of 30 W above and below and 60 W above the highest work rate, as well as the maximum work rate achieved during the incremental exercise test were chosen, while at 110 r.min-1, the power outputs chosen were 25 W above and below as well as 50 W above the highest work rate achieved during the incremental exercise test and also the maximum work rate achieved during the incremental exercise test were chosen. These four work rates for each pedalling frequency were chosen because they would have exercise times to exhaustion in the range of 1-10 minutes. Each exercise bout was preceded by four minutes of unloaded cycling and then the work rate was adjusted quickly to the desired load setting by the previously programmed computerised ergometer. The results of this work indicate that for the group of subjects studied, pedalling a cycle ergometer at 50 r.min-1 allows subjects to pedal for a significantly greater time than when pedalling at either 90 or 110 r.min-1. phiPA at 50 r.min-1 was significantly greater than when pedalling at either 90 (F(1,21) = 7.47, p < 0.01) or 110 r.min-1 (F(1,21) = 10.83, p < 0.0005). There was no significant (p > 0.22) difference between phiPA at 90 and 110 r.min-1, F(1,21) = 1.36. W' however, was not significantly different when the data for 50 r.min-1, 90 r.min-1 and 110 r.min-1 were compared (F50 r.min-1 (1,21) = 0.95; p > 0.41; F90 r.min-1(1,21) = 0.79, p > 0.53; F110 r.min-1 (1,21) = 0.78, p > 0.53). Our hypothesis, that endurance performance was reduced when recreational cyclists pedal at a high cadence when compared to a low cadence was correct. Maximum sustainable power output during cycle ergometry was higher at 50 r.min-1 than at either 90 or 110 r.min-1. At the intermediate cadence endurance was better than at the high but worse than at the low cadence. In conclusion, during endurance cycling, recreaional cyclists should pedal at lower rather than higher cadences.

Adult↗

PubMed1984

EEG spectral power and coherence analysis in healthy full-term neonates.

Continuous, bipolar EEG recording was performed in nineteen healthy full-terms during quiet sleep (Q), REM sleep (R) and wakefulness (W). Spectral power was calculated for the bilateral fronto-central (FC), centro-parietal (CP), parieto-occipital (PO) and temporal (TT) derivations. Coherence was determined for the interhemispheric biFC, biCP, biPO and biTT locations, as well as for the left and right intrahemispheric FC-PO and TT-PO combinations. Power was highest in Q in the CP derivations at 0.4-12/s. Generally, power was higher in Q than in R. In most derivations, Q and R power ran parallel. W power behaviour was different. Up to 8/s, power in W was intermediate between Q and R power. From 10/s, it became highest, particularly in the TT and FC derivations. PO power was low. Highest coherence values occurred in the lowest frequencies. Up to 8/s, biFC, biCP and biPO interhemispheric coherences were highest in R and usually lowest during Q. In the alpha-beta range, highest coherences occurred during Q and lowest during R or W, without much variance between stages. BiPO coherences were remarkably high during all stages. BiTT and intrahemispheric coherences were low and less consistent. These data suggest high synchronization of theta-delta activity between biPO regions, particularly during R. We hypothesize active common generators of neonatal theta-delta activity in the posterior regions, indicating less autonomy and more interdependent behaviour of these areas especially during R.

Cerebral Cortex↗

PubMed2004

In search of temporal power laws in the orientational relaxation near isotropic-nematic phase transition in model nematogens.

Recent Kerr relaxation experiments by Gottke et al. have revealed the existence of a pronounced temporal power law decay in the orientational relaxation near the isotropic-nematic phase transition (INPT) of nematogens of rather small aspect ratio, kappa (kappa approximately 3-4). We have carried out very long (50 ns) molecular dynamics simulations of model (Gay-Berne) prolate ellipsoids with aspect ratio 3 in order to investigate the origin of this power law. The model chosen is known to undergo an isotropic to nematic phase transition for a range of density and temperature. The distance dependence of the calculated angular pair correlation function correctly shows the emergence of a long range correlation as the INPT is approached along the density axis. In the vicinity of INPT, the single particle second rank orientational time correlation function exhibits power law decay, (t(-alpha)) with exponent alpha approximately 2/3. More importantly, we find the sudden appearance of a pronounced power-law decay in the collective part of the second rank orientational time correlation function at short times when the density is very close to the transition density. The power law has an exponent close to unity, that is, the correlation function decays almost linearly with time. At long times, the decay is exponential-like, as predicted by Landau-de Gennes mean field theory. Since Kerr relaxation experiments measure the time derivative of the collective second rank orientational pair correlation function, the simulations recover the near independence of the signal on time observed in experiments. In order to capture the microscopic essence of the dynamics of pseudonematic domains inside the isotropic phase, we introduce and calculate a dynamic orientational pair correlation function (DOPCF) obtained from the coefficients in the expansion of the distinct part of orientational van Hove time correlation function in terms of spherical harmonics. The DOPCF exhibits power law relaxation when the pair separation length is below certain critical length. The orientational relaxation of a local director, defined in terms of the sum of unit vectors of all the ellipsoidal molecules, is also found to show slow power law relaxation over a long time scale. These results have been interpreted in terms of a newly developed mode coupling theory of orientational dynamics near the INPT. In the present case, the difference between the single particle and the collective orientational relaxation is huge which can be explained by the frequency dependence of the memory kernel, calculated from the mode coupling theory. The relationship of this power law with the one observed in a supercooled liquid near its glass transition temperature is explored.

Journal Article↗

PubMed2001

Changes in short-term power output in 10- to 12-year-olds.

In this study, we used multi-level regression modelling to assess the influence of age, sex, body size, skinfold thicknesses, maturity, thigh muscle volume and isokinetic leg strength on the development of load- and inertia-adjusted peak (1 s) and mean power (30 s) determined using the Wingate anaerobic test. Fifteen males and 19 females were measured twice, first aged 10.0 +/- 0.3 years and then aged 11.8 +/- 0.3 years. Initial models identified body mass and height as significant explanatory variables (P < 0.05) for peak power and mean power, with an additional age effect for the former. No significant differences between the sexes or maturity effects were observed for either peak or mean power (P > 0.05). The introduction of sum of skinfolds improved the fit of the model and rendered the height term non-significant for both peak and mean power (P> 0.05). An age effect became apparent for mean power. When isokinetic leg strength and thigh muscle volume were entered into the model, the latter exerted a significant effect on both peak and mean power (P< 0.05), whereas isokinetic leg strength was not a significant explanatory variable for either (P> 0.05). In conclusion, thigh muscle volume exerts a positive influence on young people's short-term power output, which is additional to the effects of body mass, sum of skinfolds and age.

Age Factors↗

PubMed2006

The relative power output and relative lean body mass of World and Olympic male and female champions with implications for gender equity.

A uniform measure of the gender-related differential performance of female and male Olympic and World champions is proposed: relative power output applied to the environment. Laws of physics are employed to derive equations for estimating relative power output. In previous controlled laboratory studies, equally trained male and female athletes were shown to have a relative power output not significantly different from relative lean body mass. As to the estimated power output for 32 Olympic and World championship events contested between 1976 and 2004, eight in running, four in speed skating, three in jumping, twelve in swimming and five in rowing: 100% of the 32 event mean percentage differences in power output and 96% of the 411 event percentage differences in power output are within one standard deviation of the appropriate lean body mass percentage difference, consistent with equality of training. For 1952-1972, significantly higher percentage differences in power output are estimated in running and swimming compared with 1976-2004, consistent with women being less well trained than men during that earlier period. It is noted that efforts in recent years to provide equality of opportunity for female athletes coincide with equalization of estimated relative power output in competition with the relative lean body mass.

Body Composition↗

PubMed2005

Effect of visual perception, visual function, cognition, and personality on power wheelchair use in adults.

The purpose of this study was to determine to what extent visual perception, visual function, cognition, and personality traits affect power wheelchair use in adults. It also proposes to establish baseline information to help clinicians determine or predict power wheelchair driving performance and to develop service plans to address those driving skills that need improvement or compensation. Sixty-two adult power wheelchair users were recruited. Standardized instruments were used to evaluate visual perceptual skills, visual function, cognitive skills, and personality traits. The results of these evaluations were then correlated with participants' scores on a power wheelchair performance test. Strong correlations were found between power wheelchair driving performance and visual perception (p = .000), ocular motor function (p = .000 and p < or = .001), stereodepth perception (p < or = .001), and alertness to the environment (p < or = .001). No significant correlations were found between personality traits and power wheelchair driving performance. These results indicate that good visual perceptual skills, visual function, and various aspects of cognition are necessary for proficient power wheelchair use. These data will assist clinicians in identifying significant factors to consider when evaluating and training clients for power wheelchair use.

Activities of Daily Living↗