Is time limit at the minimum swimming velocity of VO2 max influenced by stroking parameters?

The aim of this study was to observe the relationship between time limit at the minimum velocity that elicits maximal oxygen consumption (TLim-v VO2 max) and stroke rate, stroke length, and stroke index. 13 men and 10 women, highly trained swimmers, performed an intermittent incremental test for v VO2 max assessment and an all-out swim to estimate TLim-v VO2 max. The mean +/- SD TLim-v VO2 max, v VO2 max, stroke rate, stroke length, and stroke index values were 233.36 +/- 53.92 sec., 1.40 +/- .06 meter/sec., 35.58 +/- 2.89 cycles/min., 2.39 +/- .22 meter/cycle, and 3.36 +/- .41 meter2/(cycle x sec.), respectively. The correlation between TLim-v VO2 max and stroke rate was -.51 (p < .01), and values for TLim-v VO2 max with stroke length (r = .52, p < .01) and stroke index (r = .45, p < .05). These results seem to suggest that technical skill is a key factor in typical efforts requiring prolonged aerobic power.     

A probabilistic model for the discrimination of visual number

This paper proposes a probabilistic model of how humans identify the number of dots within a briefly presented visual display. The model is an application of Thurstone’s law of comparative judgment, and it is assumed that the internal representation of numerosity consists of log-spaced random variables. The discrimination between any two different numerosities is consequently described as a function of max/rain, where max and rain are the larger and smaller numbers, respectively. The model was tested in two experiments in which the Weber fraction for numerosity, corresponding with the critical ratio of max and min, was found to have the value of 162. It was concluded that the classical span of subitizing numerosity is but a special case of the span of discrimination.     

Evidence of improved shooting precision in biathlon after 10 weeks of combined relaxation and specific shooting training

The aim of this study was to test the hypothesis that a combined relaxation (applied tension release, ATR) and specific shooting training regimen may enhance shooting ability of biathlon athletes. Seven biathletes of high national level were randomized into an experimental group (age 20 ± 5 years; Vo2max 60 ± 8 mL kg(-1) min(-1)) and were asked to add this special training intervention to their regular training for 10 weeks, while five other biathletes served as controls (age 19 ± 2 years; Vo2max 57 ± 10 mL kg(-1) min(-1)). The shooting ability of the subjects was assessed before and after the intervention at rest and after roller skiing on a treadmill in a laboratory-based competition simulating assessment. After the intervention period, the experimental group demonstrated a significantly enhanced shooting performance compared to the control group. No changes in Vo2max or in heart rate and Vo2 responses were observed before and after the intervention in either group and there were no differences between the groups in these parameters. Thus, the preliminary conclusion is that a combination of ATR and specific shooting training seems to be instrumental in enhancing the shooting performance in biathlon.     

Lexical and sublexical units in speech perception

Saffran, Newport, and Aslin (1996a) found that human infants are sensitive to statistical regularities corresponding to lexical units when hearing an artificial spoken language. Two sorts of segmentation strategies have been proposed to account for this early word-segmentation ability: bracketing strategies, in which infants are assumed to insert boundaries into continuous speech, and clustering strategies, in which infants are assumed to group certain speech sequences together into units ( Swingley, 2005 ). In the present study, we test the predictions of two computational models instantiating each of these strategies i.e., Serial Recurrent Networks: Elman, 1990 ; and Parser: Perruchet & Vinter, 1998 in an experiment where we compare the lexical and sublexical recognition performance of adults after hearing 2 or 10 min of an artificial spoken language. The results are consistent with Parser's predictions and the clustering approach, showing that performance on words is better than performance on part-words only after 10 min. This result suggests that word segmentation abilities are not merely due to stronger associations between sublexical units but to the emergence of stronger lexical representations during the development of speech perception processes.     

Exercise duration and mood state: how much is enough to feel better?

The effects of exercise duration on mood state were examined. In a repeated-measures design, the Profile of Mood States inventory (D. M. McNair, M. Lorr, & L. F. Droppleman, 1971) was administered before and after 1 quiet resting trial and 3 exercise trials of 10, 20, and 30 min on a bicycle ergometer. Heart rate levels were controlled at 60% of the participant's estimated VO2max level. An overall analysis of variance found improved levels of vigor with reduced levels of confusion, fatigue, and total negative mood. Planned analyses revealed that the improvements in vigor, fatigue, and total mood occurred after 10 min of exercise, with progressive improvements in confusion over 20 min and with no additional improvement over longer periods. These results complement current recommendations, which suggest that to experience positive fitness and health benefits, healthy adults should participate in a total of 30 min of moderate physical exercise daily, accumulated in short bouts throughout the day.     

Decreased activation in the primary motor cortex area during middle-intensity hand grip exercise to exhaustion in athlete and nonathlete participants

It remains unclear whether activation kinetics in the motor cortex area is affected by training. The purpose of the present study was to examine the effect of training on the motor cortex activation. To accomplish this, the correlation between maximal voluntary contraction and motor cortex (M1) activity was examined. Differences in the motor cortex activation between two groups during exercise were examined in 14 male volunteer participants (M age 25.2 yr., SD = 1.4): seven highly trained athletes (VO2max = 60 ml/kg/min.; maximal voluntary contraction > 55 kg, M MVC = 63.6 kg, SD = 4.2) and seven nonathletes (VO2max < 45 ml/ kg/min.; MVC < 50.0 kg, M MVC = 4 3.5 kg, SD = 5.2). Participants were familiarized with the study protocol during which they performed a maximal voluntary static handgrip test. Specifically, M1 activation was measured by near-infrared spectroscopy throughout a handgrip exercise in which participants performed a sustained middle-intensity handgrip exercise (50% of maximal voluntary contraction) until voluntary exhaustion. In the Athlete group, activation in the M1 at voluntary exhaustion fell below the resting value. In the Nonathlete group, activation in the M1 was elevated throughout the exercise. Results suggest that motor signals from the motor cortex area correlate with exercise training status, especially during fatiguing exercise.     

An approach to prediction of performance using behavioral and physiological variables

10 male, middle-distance runners selected for their potential or actual success in running 1500 metres were subjected to laboratory tests of VO2 max and run time at 85% VO2 max. Using the Eysenck Personality Inventory (Eysenck, 1962), data were collected from the runners from which they were given a score on the Extraversion/Introversion dimension of personality. Pearson product-moment correlations were computed between 1500 m. run times and VO2 max, 85% utilization of VO2 max, and Extraversion scores. The highest correlation was between Extraversion and the 1500-m. run (r = .75). The multiple correlation between times for the 1500-m. run and Extraversion with VO2 max was .77. The results support the value of building comprehensive profiles for the athlete which include not only physiological and anatomical variables but behavioral measures as well.     

The effects of circumferential air-splint pressure on flexor carpi radialis H-reflex in subjects without neurological deficits

The purposes of this study were to investigate the effects of circumferential pressure on flexor carpi radialis (FCR) H-reflex in subjects without neuromuscular deficits and to evaluate the skin's contribution to this effect. FCR H-reflex was assessed in 43 subjects by measuring the peak-to-peak amplitude change before, during, and after circumferential pressure was applied to the forearm. Twelve H-reflexes (H/M ratio: M = 25%, SD = 14) were recorded before pressure application to obtain a baseline value (H(baseline)) to which all data were compared. A pneumatic 15 to 20-cm air splint inflated to 51-60 mmHg provided the pressure around the forearm. H-reflex recordings were taken at 1, 3, and 5 min. during (H(pressure)) and after pressure application. A second smaller study (placebo), in which the air splint was inflated to 0 mmHg, was conducted in 5 subjects to ensure that changes in reflex amplitudes were not a result of cutaneous effects. Two types of responses were observed in the FCR H-reflex following pressure application. One group of subjects significantly increased in H-reflex amplitude while another group decreased in H-reflex amplitude when compared to H(baseline). Regression analysis found that H(max) explained 37.2% of the variance when controlling for H(baseline). Subjects with larger H(max) showed an increase in H(pressure) while subjects with lower H(max) showed decreases in H(pressure) The placebo study revealed no differences in H-reflex amplitude from baseline values, implying that skin stimulation from the air splint has no role in the effects observed. The dichotomous result indicates that pressure influences the upper extremity differently than it does the lower extremity in certain individuals. Clinicians, using circumferential pressure as a therapeutic modality to lower muscle activity of the upper extremity, need to be cognizant that pressure may have contrasting effects on their patients.     

Regulation of exercise intensity using ratings of perceived exertion during passive visual distraction

The purpose of this investigation was to determine if passive visual distraction altered ability to regulate exercise intensity as, assessed by ratings of perceived exertion during a 30-min. treadmill run. 10 trained females (VO2max, 52.7 ml.kg-1.min.-1) performed a graded exercise test on a treadmill to assess maximal aerobic power and rating of perceived exertion, oxygen uptake (VO2), heart rate, and running velocity at the 2.5 mmol.L-1 blood lactate concentration. Subjects then used the target rating of perceived exertion to regulate exercise intensity during a control condition, and two treatment runs with passive visual distractions. During the treatment sessions, the subjects ran on a treadmill while viewing a high-action or a low-action video with no audio. The subjects were allowed to adjust the treadmill speed throughout the run to maintain the target rating of perceived exertion; however, subjects were not allowed to view the speed setting. There were no significant differences in blood lactate concentration among the conditions for the control, low action, high action, or graded exercise test (p < or = .05). No significant differences in VO2 or running velocity were found within or among the 30-min. treatment runs and the graded exercise test. Heart rate at 5 min. of exercise during control (158 +/- 3 b.min.-1), low action (158 +/- 3 b.min.-1), and high action (159 +/- 2 b.min.-1) was significantly lower than the graded exercise test (169 +/- 3 b.min.-1). Based on the data collected, visual passive distraction did not alter regulation of intensity using ratings of perceived exertion during a 30-min. treadmill run.     

Exercise interventions and their effects on physical self-perceptions of male university students

The purpose of the present study was to examine the effects of 12-week exercise interventions on physical self-perceptions of male university students. The study also aimed to investigate the relationships between the changes in physical self-perceptions and the changes in some physiological measures after 12-week exercise programs. Forty-eight male university students aged from 19 to 25 years were enrolled in this study. Participants were randomly and equally assigned to swimming, running, cycling and control conditions. The Physical Self-Perception Profile was administered to all participants before and after 12-week exercise programs. Additionally, strength, maximal oxygen uptake (VO(2max)) and body compositions were assessed before and after interventions. Participants in the exercise groups attended swimming, running or cycling sessions for 40 min per day, 3 days per week with 60-70% of their heart rate reserves, while those in the control group did not attend any regular physical activity. The results of 4 × 2 × 5 MANOVA with the dimensions of physical self-perceptions as within-subject factor revealed that all groups including the control group revealed better physical-self-perceptions from pre- to post-test. Results of 4 × 2 × 3 MANOVA with physiological measures as within-subject factor revealed that VO(2max) values of participants in the swimming group improved more than the other groups. On the other hand, no significant differences were observed in strength scores and body fat levels among groups. Furthermore, no significant associations were obtained between the changes in physical self-perception dimensions and the physiological measures.     

Reliability and validity of the tritrac-R3D accelerometer during backpacking: a case study.

This study investigated the utility of the Tritrac-R3D accelerometer as a reliable and valid instrument in the quantification of physical activity while backpacking in the field and to evaluate heart-rate responses and oxygen consumption to assess the feasibility of using the Tritrac-R3D to estimate caloric expenditure. Two 7-day backpacking expeditions were conducted in two consecutive years by a single subject at Grand Canyon National Park, Arizona. The average hiking heart rate ranged front 60% to 77% HRmax during the expeditions. The average rate of estimated caloric cost ranged from 6.8 to 11.7 kcals x min.(-1) (equivalent to 408 to 702 kcals x hr.(-1)), indicating a relatively moderate to high level of exertion. The Tritrac had adequate consistency and reliability in the field between the two expeditions in recorded activity counts. The Tritrac underestimated caloric expenditure during backpacking with changes in terrain, and hiking speed contributed to even greater disparity in accuracy.     

Accuracy of two simple methods for the assessment of health-related physical fitness

We have developed a useful equation for estimating health-related physical fitness age. This version of health-related fitness age was developed as an extension of the biological age index and is useful for evaluation of individual differences in functional abilities of middle-aged and older adults. This measure consists of 4 independent variables fitness (VO2 max, standing trunk flexibility, %fat, and grip strength). However, direct measurement of maximal oxygen uptake (VO2 max) is an invasive clinical procedure and not practical for large scale work. In the current study, we attempted to assess the fitness age more feasibly. We selected a questionnaire method and a 12-min. submaximal treadmill walk test as substitutes for the VO2 max test. The three fitness ages were computed for 23 Japanese men (M(age) 54.7 +/- 10.7 yr.), using actual VO2 max (actual fitness age), questionnaire VO2 max (predicted questionnaire fitness age), and treadmill VO2 max (predicted treadmill fitness age). Predicted questionnaire fitness age (61.0 +/- 10.5 yr.) and predicted treadmill fitness age (60.0 +/- 12.4 yr.) were significantly correlated with actual fitness age (60.1 +/- 12.4 yr.) (r= .96 and .97, respectively). There were no significant differences among the three indices, but there was a significant difference between actual fitness age and chronological age (p<.05). For VO+/-2 max substituting the questionnaire for the treadmill estimate is acceptable in assessing fitness age and reducing the clinical risk for middle-aged and older Japanese men.     

Evaluating mixture modeling for clustering: recommendations and cautions

This article provides a large-scale investigation into several of the properties of mixture-model clustering techniques (also referred to as latent class cluster analysis, latent profile analysis, model-based clustering, probabilistic clustering, Bayesian classification, unsupervised learning, and finite mixture models; see Vermunt & Magdison, 2002). Focus is given to the multivariate normal distribution, and 9 separate decompositions (i.e., class structures) of the covariance matrix are investigated. To provide a link to the current literature, comparisons are made with K-means clustering in 3 detailed Monte Carlo studies. The findings have implications for applied researchers in that mixture-model clustering techniques performed best when the covariance structure and number of clusters were known. However, as the information about the shape and number of clusters became unknown, degraded performance was observed for both K-means clustering and mixture-model clustering.     

Differential relational encoding of categorical information in memory for action events

Memory for action phrases is better if the actions are enacted in subject-performed tasks (SPTs) than if they are only listened to in verbal tasks (VTs). This effect is ascribed to better item-specific encoding of SPTs than of VTs. The role of interitem relational information is controversial, and the findings of clustering with categorically structured lists are inconsistent (see Engelkamp, 1998). The present study contributes to clarifying these effects by demonstrating that intentional relational encoding can be used more efficiently in VTs than in SPTs and influences the degree of clustering. If the list structure is not obvious, inducing intentional encoding by presenting the category labels prior to list presentation and asking subjects to use this preinformation increases clustering in VTs but not in SPTs. Without preinformation, clustering scores of VTs and SPTs did not differ, with preinformation, clustering of VTs was stronger than that of SPTs. The authors suggest how the inconsistent findings with regard to clustering effects can be explained.     

PARTICIPATION RATES AND MAXIMAL PERFORMANCE:

Abstract— Can the superiority of some countries and groups at certain activities be explained solely by the relative sizes of the participating populations? We focus on the expected highest achievement, max, as a function of the participating group's size For several relevant statistical distributions, max can be shown to be approximately log-linear in sample size, with a slope of about 0 7 SD units We use this relation (max is log-linear ∼0 7 MILL7) to examine differences in performance in chess by men and women and by different countries The expected differences under MILL7 are very close to the observed differences We also examine the implications of MILL7 for the interpretation of other group differences and discuss its limitations     

Iterative inverse factor analysis—A rapid method for clustering persons

By interchanging persons and items, iterative inverse factor analysis provides a relatively inexpensive way of clustering persons according to their patterns of response to the items. In addition to permitting the clustering of large numbers of persons, the technique enables one to determine the bases for such clustering. The items of behavior used can be heterogeneous in content and form.     

Cluster Analytic Detection of Biological Sex: A Second Look

Golden and Meehl (1980) conducted a simulation with MMPI items to determine the accuracy of six popular clustering methods in detecting biological sex. They concluded that the results were "poor to mediocre" and that clustering methods have limited potential for contributing to knowledge. Their conclusion is inconsistent with the prior Monte Carlo literature on cluster analysis. A second look at the Golden-Meehl results reveals satisfactory clustering performance when they used the better MMPI item sets. Using Ward's clustering method and vocational interest items, the Golden-Meehl design was replicated with conditions providing a firmer inferential base. The replication results matched the favorable Golden-Meehl trials. In general, the results showed that Ward's method performed well when clustering was done with the more appropriate items.