Effects of a Three-Set Tennis Match on Knee Kinematics and Leg Muscle Activation during the Tennis Serve.

The purpose of this study was to determine the effect of a three-set tennis match on knee kinematics and leg muscle activation during the tennis serve in a real-time environment. Motion capture data and wireless electromyography of hamstrings and quadriceps muscles were collected from the back leg during the serve. A reduction of maximum knee flexion angle and a decrease of electromyography amplitudes in leg muscles were observed during the match. However, the knee angular velocity and the electromyography frequency of leg muscles remain unchanged throughout the match. The intermuscular compensation strategy to counteract fatigue might explain that the knee angular velocity was maintained despite reductions in knee flexion angle and electromyography activity of leg muscles.

Effect of the Power Balance® band on static balance, hamstring flexibility, and arm strength in adults.

The purpose of this study was to determine the effect of Power Balance® bands on strength, flexibility, and balance. Strength and flexibility were measured using the MicroFit system. Strength was measured via a bicep curl and flexibility via the sit-and-reach method. Balance was measured by the BIODEX System SD. There were 4 different conditions for the balance test: eyes open on a firm surface (EOFS), eyes closed on a firm surface (ECFS), eyes open on a foam surface (EOFoS), and eyes closed on a foam surface (ECFoS). There were 24 subjects in the study (10 men and 14 women). A counterbalance, double-blind, placebo, controlled within-subject design was used. Each of the subjects participated in 3 treatment sessions, consisting of Power Balance®, placebo band, and no band. An alpha level of p ≤ 0.05 was set a priori. There were no significant differences in strength, flexibility, or balance with regard to the treatments used. There was a significant difference between the conditions in the balance test (p = 0.000): EOFS (0.51), ECFS (0.68), EOFoS (0.99), and ECFoS (2.18); however, these were independent of the treatment conditions. The results indicate that the Power Balance® bands did not have an effect on strength, flexibility, or balance.

Effects of information processing load in abstinent and nonabstinent smokers' psychomotor task performance.

Recent evidence has indicated that nicotine, the active agent in tobacco, may affect mental abilities of smokers. To better understand the effects of nicotine on central processing, we used a basic chronometric approach to studying information processing. This chronometric approach allowed for the independent examination of nicotine's effects on two theoretically nonoverlapping information-processing stages, stimulus identification and response programming. Two stimulus intensity and four distance traversed conditions were used to affect the stimulus identification and response programming stages, respectively. The 11 subjects completed two experimental sessions (nicotinized and denicotinized), which were conducted 1 week apart. Each experimental session comprised two tests. The first test consisted of abstinent baseline measures, and the second test was administered after subjects smoked an investigator-supplied nicotinized or denicotinized cigarette. Data analysis revealed that the higher intensity stimulus elicited faster reaction times, as did the shorter movement distances, thus confirming successful manipulation of both the stimulus identification and response programming stages of the information-processing model. Furthermore, the significant improvement in reaction-time performance over baseline abstinent levels was consistent despite the manipulations made within the stimulus identification stage of processing, demonstrating that no interaction existed between stimulus intensity and the administration of nicotine. Interestingly, these data provide initial evidence that although nicotine may not affect the programming of very simple movements, it has a more pronounced effect on more complex movements. Although distance traversed had a reliable effect on movement time, nicotine had no observable effect.

Information processing capacity while wearing personal protective eyewear.

It is difficult to overemphasize the function vision plays in information processing, specifically in maintaining postural control. Vision appears to be an immediate, effortless event; suggesting that eyes need only to be open to employ the visual information provided by the environment. This study is focused on investigating the effect of Occupational Safety and Health Administration regulated personal protective eyewear (29 CFR 1910.133) on physiological and cognitive factors associated with information processing capabilities. Twenty-one college students between the ages of 19 and 25 years were randomly tested in each of three eyewear conditions (control, new and artificially aged) on an inclined and horizontal support surface for auditory and visual stimulus reaction time. Data collection trials consisted of 50 randomly selected (25 auditory, 25 visual) stimuli over a 10-min surface-eyewear condition trial. Auditory stimulus reaction time was significantly affected by the surface by eyewear interaction (F2,40 = 7.4; p < 0.05). Similarly, analysis revealed a significant surface by eyewear interaction in reaction time following the visual stimulus (F2,40 = 21.7; p < 0.05). The current findings do not trivialize the importance of personal protective eyewear usage in an occupational setting; rather, they suggest the value of future research focused on the effect that personal protective eyewear has on the physiological, cognitive and biomechanical contributions to postural control. These findings suggest that while personal protective eyewear may serve to protect an individual from eye injury, an individual's use of such personal protective eyewear may have deleterious effects on sensory information associated with information processing and postural control.

Effect of five weeks of strength and flexibility training on associations between self-reported and performance-based measures of physical fitness in older African-American adults.

Previous research suggests that older adults' perceptions of personal physical fitness are limited, especially for muscular strength and flexibility, and that these perceptual limitations may be the result of an insufficient referent for discerning appropriate muscular strength and flexibility. This study evaluated whether 5 wk. of strength and flexibility training would provide the additional experiences necessary for older adults to strengthen the correlations between their self-reported and performance-based measures of physical fitness, specifically for the subcomponents of strength and flexibility. Evaluated components were aerobic endurance (maximal distance covered in 6 min.), muscular strength (maximal amount of weighted arm-curls and chair ups), flexibility (back-scratch and modified sit and reach), and body composition (BMI). From a local community center a convenient sample of 20 African-American adults (5 men and 15 women) who ranged in age from 57 to 82 years (M=68 yr., SD=5 yr.) volunteered to participate in 5 wk. of strength and flexibility training (twice a week, 60 min. per session). Initially, the absolute value of correlations between self-reported and performance-based measures of physical fitness were low to moderately high (r=.35 to .68) with the greatest correlation found for body composition (r=-.68). After 5 wk. of training, the participants' self-reports of upper body flexibility significantly improved (r=.42 to .70); however, no significant changes were found in self-reports of muscular strength and lower body flexibility. Additional validation of available self-report scales, as well as the development of new and improved self-report ones, is needed.

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.

Nicotine deprivation effects on the dissociated components of simple reaction time.

The effect of smoking abstinence on the dissociated components of a simple reaction-time response was investigated. 7 subjects completed two experimental sessions conducted one week apart. Each experimental session was comprised of two tests. The first test consisted of abstinent baseline measures, while the second test was administered after smoking either an investigator-supplied nicotinised or denicotinised cigarette. A within-subjects design was utilized which permitted each subject to be their own control. Interestingly, the smoking of either experimenter-controlled cigarette (nicotinised or denicotinised) reliably decreased the subjects' desire to smoke. More importantly, however, was that only the nicotinised cigarette had any influence on simple reaction time. Moreover, this decrease in reaction time was isolated within the premotor or cognitive processes. In fact, there was no evidence that the smoking of a nicotinised cigarette had any effect on the motor-time component of this task. These findings are relevant for two reasons, (1) performance decrements due to smoking abstinence were independent of the urge or craving to smoke and (2) nicotine affects cognitive and motor processes of a simple reaction-time task differently.