Lateral dominance of legs in maximal muscle power, muscular endurance, and grading ability.

The purpose of this study was to examine lateral dominance in maximal muscle power, muscular endurance, and grading ability, using isokinetic mulscular strength in knee extension and flexion. The subjects were 50 healthy male students whose ages ranged from 19 to 23 years (M height: 173.6+/-6.2 cm, M weight: 67.2+/-6.8 kg). Their dominant legs for power exertion and for functional use were based on questionnaire items selected from those used in previous studies. The angular velocities of extension and flexion for exerting maximal muscle power were 60, 180, and 300 x sec.(-1). A continuous exertion 30 times at an angular velocity of 180 sec.(-1) was used as the load for muscular endurance. For grading ability, 25%, 50% and 75% of the maximal muscle strength at angular velocities of 60 and 180 x sec.(-1) were the required values, and the difference between these values and the exerted muscular strength was evaluated. The dominant leg and nondominant leg were compared for both power exertion and functional use. There was no lateral dominance in maximal muscle power and muscular endurance. In muscular endurance, especially, some subjects showed one leg superior in power exertion and some superior in functional use. Lateral dominance was noted across maximal muscle power and muscular endurance in grading ability. The dominant leg tended to be better than the nondominant leg in functional use. However, lateral dominance was not remarkable for flexing motion and in exertion for a short time.     

Measurements of Muscular Strength,Endurance, and Recovery Over Fifteen Successive Days

Muscular output was measured in terms of strength, endurance, impulse, and recovery, with 10 Ss, 4 times per day over 15 successive days. A general index (the mean percentage of baseline performance with all measures) indicated that performance generally improved over the first 5 or 6 days, and remained relatively stable thereafter. The measures of strength were sensitive to within-day effects, whereas endurance and recovery measures were not influenced by such circadian rhythms.     

Muscular Fatigue and the Learning and Performance of a Motor Control Task

Four groups of 12 female college students performed a pursuit-rotor task during learning under one of four conditions of exercising the muscles of the limb used in the task: (a) no muscular exercise, (b) low-fatiguing, (c) medium-fatiguing, and (d) high-fatiguing muscular exercise. All four groups were tested 48 hr later on the same pursuit-rotor task with no exercise interpolated between the ten 20-sec trials. Differences in the performances among the four groups were not statistically significant on either the first or the second day alone or when the data of the two days were combined. The data appear to support the hypothesis of an inverted-U or inverted-J model relating performance (and learning) to muscular fatigue in motor-control tasks.     

Effects of Training on Endurance in Hanging by The Hands

The effect of training on endurance in hanging by the hands from a horizontal bar was examined by timing the duration of such hanging in six male and five female subjects each weekday for 2 weeks. A significant increase in endurance was observed. The results, both subjective and objective, indicated the most important factors in the training to be increased psychological endurance of discomfort and increased muscular strength and efficiency.     

Effects of Local Muscular Fatigue Due to Isotonic and Isometric Exercise Upon Fractionated Reaction Time Components

Fractionated RT for a right knee-extension task was assessed on eight male and eight female Ss over eight treatment days. Following four consecutive days of 75 RT trials /day to insure stabilized strength and RT components, Ss were administered two days of bench stepping and two days of isometric exercise designed to induce muscular fatigue of the knee extensors. Significant strength decrements of up to 24% were induced by both the isotonic (bench stepping) and isometric exercise treatment conditions but no changes were observed in fractionated RT components. The results would seem to indicate that performance differences in fine-versus gross-motor skill tasks due to fatigue need to be more carefully examined.     

Muscular fitness,motor competence,and processing speed in preschool children

ABSTRACT

The aim of this study was to examine the relationship between muscular fitness and motor competence and processing speed in preschool children. Eighty-four preschool-aged children were recruited and underwent assessments for muscular fitness (muscular endurance and power), motor competence, and then participated in an auditory oddball task. The findings showed that muscular fitness and motor competence were associated with shorter reaction times after controlling for confounding factors. These findings provide tentative support for a positive association between muscular fitness and motor competence and processing speed in preschool children.

abbreviations:

Reaction time (RT); Institutional Review Board (IRB); Basic Motor Ability Test-Revised (BMAT); Body mass index (BMI); Preschool Children Fitness Programme (PCFP); Intraclass correlation coefficients (ICC); Thinking Creatively in Action and Movement test (TCAM); Inter-stimulus interval (ISI); Insulin-like growth factor 1 (IGF-1); Brain-derived neurotrophic factor (BDNF)     

Physical fitness differences between athletes and nonathletes: Do changes occur as a function of age and sex?

The main objectives were to determine (a) if physical fitness superiority of athletes over nonathletes increases as a function of age, and (b) if the magnitude of athlete-nonathlete fitness differences are the same in males as in females, and if these differences are consistent across ages. Approximately 3,000 students in grades 3, 7, and 11 (ages 9, 13, and 17 years) were tested on measures of static and explosive muscular strength, static and dynamic muscular endurance, cardiovascular endurance, and flexibility. MANOVA and follow-up univariate ANOVAs indicated that the higher the grade, the better the performance; males outperformed females on all measures except flexibility; and athletes were superior to nonathletes on all six test items. Furthermore, (a) there was no difference between athletes and nonathletes at grade 3, athletes were considerably better than nonathletes by grade 7, and the magnitude of the difference was virtually the same at grade 11, (b) the fitness superiority of athletes over nonathletes was essentially of the same magnitude for males as for females at each grade level.     

Development of physical ability tests for police officers: a construct validation approach.

A construct validation approach was followed to affirm that 8 physical ability test events were significantly related to two important constructs underlying the job performance of police officers: strength and endurance. A sample of 115 incumbent police officers took 8 physical ability tests and were rated by supervisors on their physical performances in their job. LISREL methods were used to test the model specified, and a reasonable fit was achieved. Portions of the model were tested on an independent sample of 161 applicants; the fit of the model was again acceptable. A nomological network of relationships, in which strength and endurance factors correlated in expected directions with other physiological and demographic variables, was hypothesized and tested. Finally, the data were examined for potential gender differences and bias. Considerable differences were shown between men and women on both test and performance variables, and women would be overpredicted if a common regression line were used for selection purposes.     

Effects of delta 9-THC on marijuana smoking, dose choice, and verbal report of drug liking.

The effects of delta 9-tetrahydrocannabinol content of marijuana on cigarette smoking, dose choice, and verbal report of drug "liking" by adult males living in a residential laboratory were investigated. Marijuana cigarettes were available during programmed intervals while subjects were engaged in recreational activities. The tetrahydrocannabinol content of the cigarettes remained constant each day, but was changed across days. Subjects provided written ratings of drug liking at the end of each day. In the first study, placebo or active (2.3% delta 9-tetrahydrocannabinol) marijuana cigarettes were available for 1-, 2-, or 3-day intervals at varying times of day. The number of cigarettes smoked was unrelated to tetrahydrocannabinol content, although verbal reports of drug liking were consistently higher when marijuana cigarettes containing tetrahydrocannabinol were smoked. In a second study, a choice procedure, consisting of four 3-day blocks of 2 sample days and 1 choice day, was used. On sampling days, subjects smoked cigarettes varying in tetrahydrocannabinol content (0.0, 2.0, and 3.5%, w/w); on choice days they were allowed to choose between the two previously sampled doses. The number of cigarettes was not consistently related to tetrahydrocannabinol content. Ratings of drug liking were increased when marijuana cigarettes contained tetrahydrocannabinol, but ratings of marijuana containing 2.0% and 3.5% of the compound were similar. In contrast, subjects consistently chose the 3.5% dose over either the 0.0% or 2.0% dose. Dose choice was more sensitive to tetrahydrocannabinol content than either reports of drug liking or numbers of cigarettes smoked.     

Use of self-reports of physical fitness as substitutes for performance-based measures of physical fitness in older adults

The purpose of the present study was to evaluate the association between self-reported physical fitness and performance-based measures of physical fitness in older adults. The specific components of physical fitness evaluated included aerobic endurance, muscular strength, and flexibility. Adults (25 men and 47 women) ranging in age from 56 to 92 years (M age=75 yr.) were recruited from the local community. Generally, the associations between self-reported and performance-based measures of physical fitness were low to moderate (r = 30-.01). Based on these findings, self-reports of physical fitness should not be used as substitutes for performance-based measures of physical fitness in older adults. Furthermore, present findings suggest that older adults, when asked to rate subcomponents of physical fitness, may not do so but rather evaluate a more general concept of physical fitness with aerobic endurance as the dominant factor.     

Gluteus medius strength, endurance, and co-activation in the development of low back pain during prolonged standing

This study measured gluteus medius (GM) strength and endurance before and after a 2 h prolonged standing task in previously asymptomatic individuals, to compare between individuals who did and did not report pain in the low back. Twenty-four participants without a history of low back pain stood in a constrained area for 2 h. Before and after the standing protocol, participant’s maximal hip abduction strength (N) and side-bridge endurance (seconds and GM myoelectric fatigue) were measured. Continuous surface EMG was collected from GM during the 2-h protocol for analysis of bilateral co-activation. Pain in the low back was rated every 15 min with a visual analog scale (VAS). Seventeen of 24 (71%) previously asymptomatic participants developed pain in the low back during the standing protocol. These participants had lower side-bridge endurance (p = .002), and higher gluteus medius (GM) co-activation (p = .002) compared to participants who did not develop pain in the low back. Hip abduction strength decreased for both groups following prolonged standing, with no between groups’ difference. Lower side-bridge endurance and hip abduction strength were significantly associated with higher GM co-activation (adjusted r² = .34), but not pain levels. Side-bridge endurance and GM co-activation, but not hip abduction strength, may have utility in identifying participants likely to develop pain in the low back during prolonged standing. The best training program for increasing GM endurance is unclear.     

Motivational antecedent beliefs of endurance, strength, and flexibility activities

Research into the correlates of physical activity has focused almost exclusively on physical activity as an omnibus construct. Health Canada and the American College of Sports Medicine, however, advocate physical activity in terms of performing regular endurance, strength, and flexibility activities. The purpose of this study was to investigate the absolute and relative contributions of behavioral, normative, and control beliefs associated with endurance, strength, and flexibility activities within a theory of planned behavior (TPB) structure. Participants were 185 undergraduates who completed measures of the TPB and a 2-week follow-up of endurance, strength, and flexibility behavior. Results using structural equation modeling and Hotelling's t-tests for dependent correlations identified different motivational antecedents for each type of physical activity (p < .05). Endurance behavior was influenced exclusively by behavioral beliefs, flexibility behavior was influenced by normative and control beliefs, and strength behavior was influenced by key behavioral, normative, and control beliefs. The different motivational profiles for each physical activity allude to the importance of tailoring interventions by physical activity type.     

Exercises focusing on rotator cuff and scapular muscles do not improve shoulder joint position sense in healthy subjects

Proprioception is essential for shoulder neuromuscular control and shoulder stability. Exercise of the rotator cuff and scapulothoracic muscles is an important part of shoulder rehabilitation. The purpose of this study was to investigate the effect of rotator cuff and scapulothoracic muscle exercises on shoulder joint position sense. Thirty-six healthy subjects were recruited and randomly assigned into either a control or training group. The subjects in the training group received closed-chain and open-chain exercises focusing on rotator cuff and scapulothoracic muscles for four weeks. Shoulder joint position sense errors in elevation, including the humerothoracic, glenohumeral and scapulothoracic joints, was measured. After four weeks of exercise training, strength increased overall in the training group, which demonstrated the effect of exercise on the muscular system. However, the changes in shoulder joint position sense errors in any individual joint of the subjects in the training group were not different from those of the control subjects. Therefore, exercises specifically targeting individual muscles with low intensity may not be sufficient to improve shoulder joint position sense in healthy subjects. Future work is needed to further investigate which types of exercise are more effective in improving joint position sense, and the mechanisms associated with those changes.     

Re-evaluation of a possible proximity effect on muscular strength

Inconsistent findings of a proximity effect of sucrose on muscular strength and a potential interaction of nutritional status prompted the current study. Double-blind, counterbalanced assessments of grip strength were performed with and without 76 subjects holding a container of sucrose. No main effect was found for proximity of glucose, and no interaction was found for prandial status.     

Perceived force in fatiguing isometric contractions

An integrative approach emphasizing both psychological and physiological components in force perception has started to emerge in motor psychophysics. In this experiment, the relation between isometric force (produced by the elbow flexors~ and perceived force was examined over a range of forces maintained until maximal endurance. A contralateral-limb matching procedure in which subjects estimated the force of a sustained, constant force contraction by contracting their unfatigued arm at regular intervals was employed. A linear increase in perceived force was observed during the fatiguing contractions, the rate of which depended on the level of force exerted. The sensation of force at maximal endurance was also found to vary with the force exerted. Based on the similarity between these results and those derived from electromyographic studies, we propose that observers use the efferent input to the muscle in preference to its afferent responses in judging the force of muscular contractions.     

Where did I park? A naturalistic study of spatial memory

A naturalistic study of spatial memory having temporary utility was conducted using 32 faculty and staff of a university, who park in non-reserved parking spaces, as subjects. The subjects, who were unaware of the study until interviewed, were asked to indicate on a map the exact location where they had parked their car on that day and on each of the three preceding days. Whereas retention accuracy decreased significantly across days, the recency effect was weak and overall retention proved to be very accurate. Of the subjects who varied their parking location, 88 per cent were able to indicate within three spaces where they parked on the day of the interview, and 58 per cent on the most remote day. Younger females made significantly larger retention errors across the four days than older females and younger and older males. Subjects' overall retention accuracy correlated with their overall confidence in their recollections (γ = .72). Daily ratings of ‘how busy on the job’, reported times left campus each day, parking location variability, particular parking lot used, and number of parking spaces in the distinct locations used were not significantly correlated with retention errors. In follow-up interviews, subjects reported preferring a behavioural, ‘park in a favourite spot’ strategy, with several types of imagery-based cognitive strategies being cited less frequently, and verbal encoding being the least often cited strategy.     

Evaluation of a possible proximity effect of aspartame and vitamin C on muscular strength

Inconsistent findings of a proximity effect on muscular strength, using a neutral control substance, prompted the current study. Double-blind, counterbalanced assessments of grip strength were performed, with subjects holding either an envelope of ascorbic acid (Vitamin C) or aspartame. No proximity effects were found despite the use of two substances believed by some applied kinesiologists to yield positive and negative results, respectively.     

Degree of learning,interpolated tests,and rate of forgetting

The purpose of the two experiments reported here was to observe the effects of degree of learning, interpolated tests, and retention interval, primarily on the rate of forgetting of a list of words, and secondarily on hypermnesia for those words. In the first experiment, all the subjects had one study trial on a list of 20 common words, followed by two tests of recall. Half of the subjects had further study and test trials until they had learned the words to a criterion of three correct consecutive recalls. Two days later, half of the subjects under each learning condition returned for four retention tests, and 16 days later, all the subjects returned for four tests. Experiment 2 was similar, except that all the subjects had at least three study trials followed by four recall tests on Day 1, intermediate tests were given 2 or 7 days later, and they all had final tests 14 days later. The results showed that rate of forgetting was attenuated by an additional intermediate set of tests but not by criterion learning. Hypermnesia was generally found over the tests that were given after a retention interval of 2 or more days. The best predictor of the amount of hypermnesia over a set of tests was the difference between overall cumulative recall and net recall on the first test of the set.     

Effects of achievement motives on wrestling ability, oxygen uptake, speed of movement, muscular strength, and technical performance

In this study was tested the prediction that approach-oriented wrestlers should perform better than indifferent- and avoidance-oriented ones. The 1970 Achievement Motives Scale of Gjesme and Nyg?rd was administered to 47 boys, and subjects' scores were sampled for four different wrestling championships on international and national level. Measured were oxygen uptake, speed of movement, muscular strength, and serial performance of five wrestling holds. Approach-oriented wrestlers performed better than indifferent-oriented ones on 9 of 15 tasks. Only in international competitive situations did the approach-oriented wrestlers perform better than the avoidance-oriented ones. Results are interpreted in terms of hypotheses about achievement motivation, and pedagogical implications are discussed.