RPE responses during arm and leg exercises: effect of variations in spontaneously chosen crank rate

The aim of this study was two-fold. First, the rating of perceived exertion (RPE) was compared between two different upper and lower body exercises. Subjects (n = 12) performed with spontaneously chosen crank or pedal rates: (i) incremental maximum power tests (Test 1), with an initial work rate of 50% of maximal power followed by increases of 10% at each 120-sec. work stage and (ii) tests (Test 2) with exercise bouts set at 20, 40, 60, and 80% of maximal power separated by passive recovery periods. Second, the effects of variations in spontaneously chosen crank rate on RPE was analysed using the second test performed only with upper body. Subjects performed Test 2 three times with crank rates spontaneously chosen by the subjects, set at plus or minus 20% of spontaneously chosen crank rate. During both Tests 1 and 2 for upper or lower body, RPE increased linearly (p<.01) with power output. No significant difference was noticed between upper and lower body tests; however, RPE was significantly different (p<.05) between Test 1 results for upper and lower body at 70, 80, 90, and 100% of maximal power. The greater RPE at high power output could be linked to the important effect of fatigue during upper body exercise. Among the three crank-rate conditions, no significant difference in RPE was noticed. The choice of crank rate does not seem to influence the perception of exertion in upper body cycling exercise.     

Visual analogue scale correlates of musculoskeletal fatigue

Visual analogue scale has been shown to reflect subjective feelings but rarely has it been used for musculoskeletal fatigue so in the present study VAS ratings were used to quantify musculoskeletal fatigue. A total of 20 students underwent a fatigue protocol (M age=21.3 yr., SD= 1.0). A series of randomized external loads at 0, 5, 10, 15, 25, 35, and 50% of the maximum voluntary contraction was generated by the BTE Primus and applied at the distal end of the dominant arm, which was sustained at the 90 degrees forward flexion position. After 60 sec. of force exertion for each loading, the subject marked the scale to reflect their extent of fatigue at the shoulder muscle. Analysis showed fatigue scores were significantly correlated with the percentages of maximum load applied (r =.73, p < or = .01). The correlation between higher external loads (25-50% maximum load) and fatigue scores was .57 (p < or = .01) and that for lower external loads (0-15% maximum load) was .44 (p < or = .01). The validity of using a visual analogue scale as a measure of musculoskeletal fatigue requires further study, particularly for a low load.     

Why did Tiger Woods shoot 82? A commentary on

In a recent article, Toner and Moran (2015) argued that athletes need to pay conscious attention to body movements, and that an external focus of attention would not be effective for continued improvement at the elite level. Their arguments appear to be based on misunderstandings of the attentional focus literature. In this commentary, I clarify that adopting an external focus does not imply that performers are not aware of their body movements. Rather, an external focus (i.e., focusing attention of the intended movement effect) refers to the preparation of movement execution. I maintain that an external focus is necessary to optimize performance and learning at any level of performance.     

Human bilateral deficit during a dynamic multi-joint leg press movement

Bilateral deficit has been used to describe the phenomenon of a reduction in performance during synchronous bilateral movements when compared to the sum of identical unilateral movements. The study of bilateral deficit in humans under isometric, and to a lesser extent, dynamic conditions has shown bilateral decreases in force and muscle activation, and delayed reaction time. Results are equivocal, however, and biomechanical analyses of dynamic conditions, i.e., movements, are lacking. Our purpose was to determine, through an analysis of kinematic, kinetic, and electromyographic (EMG) data, whether or not bilateral deficit was present during a dynamic multi-joint movement under conditions where the external load was relatively equal for unilateral and bilateral efforts. Five male participants performed repeated unilateral and bilateral maximal horizontal leg press jumps under 100% (1BW) and 200% (2BW) relative body weight loads. Significant bilateral deficits in resultant ground reaction impulse of 27.7% and 13.0% were present in 1BW and 2BW, respectively. Maximum joint power at the hip exhibited significant deficits in both 1BW and 2BW of 35.6% and 25.1%, respectively. In both 1BW and 2BW conditions, ankle (15.5% and 11.5%), knee (10.9% and 5.7%), and hip (38.5% and 30.4%) work was significantly affected. Statistically significant EMG bilateral deficits were found in every muscle in both conditions except for rectus femoris during the 2BW trials. Bilateral deficit values ranged from 9.1% to 20.9% for 1BW, while deficits between 6.1% and 20.7% were found in 2BW. These results indicate that during dynamic leg press, bilateral deficit does exist, but that individual muscle activation levels and joint kinetics are not equally affected.     

Virtual reality promotes greater improvements than video-stimulation screen on perceptual-cognitive skills in young soccer athletes

BackgroundThe literature has shown the positive effect of virtual reality (VR) in percepto-cognitive skills. However, the literature lacks findings about at what extent VR would be better than video.PurposeThis study aimed to analyze the chronic effect of VR and video-stimulation screen training on passing decision-making, visual search behavior, and inhibitory control performance in young soccer athletes.MethodA total of 26 young soccer players underwent an 8-week training protocol after being randomly assigned to the VR (n = 13) or video-screen (VID, n = 13) group. Passing decision-making, visual search behavior, and inhibitory control performance were measured before and after both interventions.ResultsA group x time interaction was found for decision-making performance (p < 0.01) and visual search behavior (p < 0.01). Both groups improved both decision-making performance (p < 0.01) and visual search behavior (p < 0.01); however, greater improvements were verified in VR (p < 0.01). Both VR and VID improved inhibitory control (p < 0.01), but no group interaction effect was observed (p > 0.05).ConclusionOur results suggest that VR leads to greater improvements in decision-making and visual search behavior in young soccer athletes than VID.     

Neuromuscular responses to platform perturbations in power- versus endurance-trained athletes

The purpose was to assess differences in postural response characteristics between two groups of elite athletes having power or endurance training. Participants were all men and included power- (M age = 21 yr., SD = 3, n = 12) and endurance-trained (M age = 22, SD = 3, n = 12) athletes. Muscle response characteristics and center of pressure measures were recorded during recovery from Fast (10 cm at 80 cm/sec.) and Slow (10 cm at 20 cm/sec.) horizontal platform perturbations. In response to Fast perturbations, power-trained athletes responded with significantly shorter times to stabilize the center of pressure, shorter muscle-contraction onset times, and larger muscle response amplitudes than endurance-trained athletes. This suggests power-trained athletes are more effective than endurance-trained athletes in responding to balance threats such as slips and trips in daily life and that power training should be studied to improve balance control of balance-impaired populations.     

The rubber hand illusion: sensitivity and reference frame for body ownership

When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed 'Rubber Hand Illusion' (RHI). We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the two hands. We created the mismatch either by adjusting stimulation or posture of the subject's hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject's hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject's hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject's hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject's hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual-tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is 'me' is interpreted with respect to a prior mental body representation.     

Body image in bulimic,dieting, and normal females

The present investigation examined body-size estimation and overvaluation of a thin shape in bulimic females, females having been obese as adults who later lost weight, females with no history of obesity who were dieting, and females with no history of obesity as adults and not currently dieting. Each subject was presented with a set of seven silhouettes, one having been drawn from the subject's actual photograph and the remaining silhouettes representing 2.5, 5, and 7.5% increases and decreases in the size of certain body areas of the original figure. Subjects selected both their actual size and their ideal size. In addition, objective raters selected an ideal size for each subject. The hypotheses that bulimics would overestimate their size or overvalue an ultrathin body size as compared with other females were not supported. A history of childhood obesity appears to influence significantly body-size overestimation. Finally, the hypothesis that bulimics would appear more dissatisfied with their body image was not supported, with the three groups currently dieting appearing equally dissatisfied with their shape.The authors greatly appreciate the assistance of the graphic artist, Susan Meier.     

我国运动员主观幸福感内部结构及外部影响因素研究

通过探索我国运动员主观幸福感的内部结构,并对我国运动员主观幸福感的外部影响因素进行分析。研究结果发现,我国运动员主观幸福感由7个二级指标及38个三级指标构成,其中负性情感、生活环境、训练竞赛、人际关系等二级指标对我国运动员主观幸福感有重要影响。竞赛水平的发挥、教练员对运动员的公平性、运动员伤残补偿制度建设、运动队管理方式、运动成绩提升空间等三级指标是影响运动员幸福感的重要外部因素。     

Psychosocial determinants of young athletes' continued participation over time

The aim of this study was to examine the differences in psychosocial and motivational variables between persistent and dropout youth athletes and between groups with different years in training. Team and individual youth athletes completed questionnaires measuring autonomy support from parents and coaches, peer motivational climate, basic psychological needs satisfaction, and sport motivation. The results showed that athletes who dropped out perceived significantly less competence, relatedness, and autonomy need satisfaction, and they perceived less autonomy support from parents and were less intrinsically motivated than persistent athletes. Youth athletes with up to one year in training reported significantly lower effort and intra-team conflict with peers, relatedness need satisfaction, and external motivation than athletes with 1 to 3 years and >3 years in training. Findings extend knowledge of the psychosocial determinants of sport continuation behaviour among young athletes.     

Muscular contribution to low-back loading and stiffness during standard and suspended push-ups

Push-up exercises are normally performed to challenge muscles that span upper extremity joints. However, it is also recognized that push-ups provide an effective abdominal muscle challenge, especially when the hands are in contact with a labile support surface. The purpose of this study was to compare trunk muscle activation levels and resultant intervertebral joint (IVJ) loading when standard and suspended push-ups were performed, and to quantify and compare the contribution of trunk muscles to IVJ rotational stiffness in both exercises. Eleven recreationally trained male volunteers performed sets of standard and suspended push-ups. Upper body kinematic, kinetic, and EMG data were collected and input into a 3D biomechanical model of the lumbar torso to quantify lumbar IVJ loading and the contributions of trunk muscles to IVJ rotational stiffness. When performing suspended push-ups, muscles of the abdominal wall and the latissimus dorsi were activated to levels that were significantly greater than those elicited when performing standard push-ups (p<.05). As a direct result of these increased activation levels, model-predicted muscle forces increased and consequently led to significantly greater mean (p=.0008) and peak (p=.0012) lumbar IVJ compressive forces when performing suspended push-ups. Also directly resulting from the increased activation levels of the abdominal muscles and the latissimus dorsi during suspended push-ups was increased muscular contribution to lumbar IVJ rotational stiffness (p<.05). In comparison to the standard version of the exercise, suspended push-ups appear to provide a superior abdominal muscle challenge. However, for individuals unable to tolerate high lumbar IVJ compressive loads, potential benefits gained by incorporating suspended push-ups into their resistance training regimen may be outweighed by the risk of overloading low-back tissues.     

Generation of forward angular impulse with different initial conditions

Generation of angular impulse during foot contact is regulated by controlling the relative orientation between the total body center of mass (CoM) and the reaction force (RF) applied to the feet. Between-task differences in initial CoM horizontal momentum were hypothesized to alter how forward angular impulse was generated during two forward translating tasks. Five skilled athletes performed standing (SFS) and running (RFS) forward somersaulting dives. Sagittal plane kinematics and RFs were obtained during the take-off phase of both tasks. The initial CoM momentum differences resulted in significant differences in control of the CoM relative to the RF, RF generation mechanisms, and knee and hip net joint moments (NJMs). During the RFS, angular impulse was generated by positioning the feet anterior to the CoM at initial contact so that the RF passed posterior to the CoM throughout the take-off phase. During the SFS, angular impulse was generated by positioning the CoM anterior to the feet prior to the push interval so that the RF passed posterior to the CoM. Task-specific differences in segment kinematics and RF direction contributed to the redistribution of knee and hip NJMs. These results suggest that initial conditions influence strategies the nervous system uses to satisfy task objectives.     

Relations of Body Mass Index,body fat,and power of various muscles to sport injuries

The aim of the present study was to estimate associations of Body Mass Index, body fat, and muscle power on sport injuries. In injured and noninjured athletes during a sport season of four months, the differences in Body Mass Index, the percent body fat, and back, leg, and right- and left-hand muscle strength were examined. The subjects were 329 men and 127 women attending classes in the departments of Physical Training and Sport of Atatürk University (Erzurum, Erzincan, and A?ri in Turkey). Body Mass Index was higher in injured athletes than in noninjured ones, but there was no difference in percent body fat between injured and noninjured athletes. The back and leg muscle power were higher for noninjured athletes than for injured ones. The right- and left-hand power was higher for injured athletes in some sports. Because the back and leg muscles function in control of equilibrium, the power of these muscles may be important for control related to avoidance of sport injuries.     

Are free testosterone and cortisol concentrations associated with training motivation in elite male athletes?

ObjectivesTo examine correlative associations between salivary free testosterone (T) and cortisol (C) concentrations and training motivation in elite male athletes.DesignSingle group, longitudinal design with repeated measures.MethodsParticipants (n = 15) completed a 5-week progressive resistance training programme. Across 2 weekly workouts, pre and post measures of salivary free T and C concentrations were taken along with voluntary chosen workload, as a proxy for training motivation. Strength and body mass were assessed pre and post training.ResultsIndividual changes in pre-workout free T concentrations correlated strongly to voluntary workloads (pooled r = 0.81, p < 0.001). Pre-workout free C concentrations was weakly correlated to voluntary workload (pooled r = 0.35). Pre-workout hormones (r = 0.57–0.89) and the strength gains were also related.ConclusionsThe salivary free T concentrations of male athletes presented before training were strongly associated with subsequent voluntary workloads, indicating a potential link to training motivation.     

Noncontingent positive and negative feedback during maximal exercise.

A closed skill, maximal effort on a bicycle ergometer was used to study the effects of noncontingent external feedback on performance, perceived effort, and the subject's assessment of the quality and accuracy of the feedback. The 47 subjects included elite athletes as well as physical education majors. They were asked to perform a series of 5 60-sec. trials of maximal effort, trials which included positive, negative, positive and negative, and no-feedback conditions. Although there were no significant effects on performance for the various feedback conditions, subjects judged the positive feedback favourably and as accurate, but negative feedback was judged unfavourably and considered to be inaccurate. This result is seen as supportive of the 1982 McCarrey, et al. supposition that successful athletes may have less need to internalize attributions of effect.     

Specific internal and external attentional focus instructions have differential effects on rowing performance

Directing an individual to focus their attention on internal or external cues can influence performance of skill-based and endurance sports. The present study examined the effects of switching attention across different types of internal and external attentional foci in a rowing task. Novice rowers (19 male, 47 female) focussed attention on one of four different internal cues (or one of four different external cues) at discrete time points while completing a row on an ergometer. Overall, a focus on internal cues resulted in longer distance, higher power output, and higher heart rate than a focus on external cues. However, for the internal condition a focus on arm and leg muscles was associated with higher performance than a focus on breathing. For the external condition, a focus on exerting force on the handle produced higher performance than a focus on the movements of the handle or seat or on the sounds of the ergometer. Global instructions to focus internally or externally influenced performance, but the specific effects within these broad categories were also variable. The advice given to athletes and recreational exercises should consider both the broad attentional focus direction and the specific cues of the task to which attention is directed.     

Incremental exercise, plasma concentrations of catecholamines, reaction time, and motor time during performance of a noncompatible choice response time task

The primary purpose was to examine the effect of incremental exercise on a noncompatible response time task. Participants (N=9) undertook a 4-choice noncompatible response time task under 3 conditions, following rest and during exercise at 70% and 100% of their maximum power output. Reaction and movement times were the dependent variables. Maximum power output had been previously established on an incremental test to exhaustion. A repeated-measures multivariate analysis of variance yielded a significant effect of exercise intensity on the task, observation of the separate univariate repeated-measures analyses of variance showed that only movement time was significantly affected. Post hoc Tukey tests indicated movement time during maximal intensity exercise was significantly faster than in the other two conditions. The secondary purpose of the study was to assess whether increases in plasma concentrations of adrenaline and nor-adrenaline during exercise and power output would act as predictor variables of reaction and movement times during exercise. Catecholamine concentrations were based on venous blood samples taken during the maximum power output test. None of the variables were significant predictors of reaction time. Only power output was a significant predictor of movement time (R2 = .24). There was little support for the notion that peripheral concentrations of catecholamines directly induce a central nervous system response.     

Effect of time of day on the relationship between mood state, anaerobic power, and capacity

Mood state was estimated in six men using the Profile of Mood States questionnaire, with a "right now" directional set prior to performance of a modified Wingate power test, once at 03.00 hr., 09.00 hr., 15.00 hr., and 21.00 hr., on different days. Anaerobic power was measured as peak power output in 5 sec., and anaerobic capacity was measured as total external work performed during the 30-sec. test. Intraindividual difference scores were calculated as a subject's score minus his mean over the four tests. Multiple regression analyses showed that time of day and the Profile of Mood States fatigue score accounted for 51% of the variance in peak power and 62% of the variance in anaerobic capacity. However, the relationships between fatigue and subsequent anaerobic power and capacity reached statistical significance only at 21.00 hr. These results suggest that intraindividual differences in the mood state are related to subsequent performance. Greater than usual levels of fatigue are associated with reduced performance capacity. However, this relationship is dynamic and is dependent upon the time of day.     

Noah J. Toly and Daniel I. Block,eds. Keeping God's Earth: The Global Environment in Biblical Perspective

Abstract

Ted Peters rightly rejects, on biblical and theological grounds, the understanding of kenosis presumably endorsed by Niels Gregersen (and with him Jürgen Moltmann, John Polkinghorne and Arthur Peacocke) as divine withdrawal from creation (tsim tsum). That said, a second version of kenosis, one more consistent with Scripture and early patristic theology, meets Peters' criticism by presenting kenosis not as a creative withdrawal of divine power but as a self-negation on the part of God that results in the generation of created reality along with God's reappearance and presence in it, albeit in another form. This is the kenosis-plerosis model, one according to which God gives history its momentum and empowers finite beings as a consequence of God's own self-negation; this would make possible a way for Gregersen meaningfully to affirm God's action at higher levels of nature without violating nature's integrity, even though it does so in a heterodox way.     

Effect of bandwidth knowledge of results on movement consistency

The effect of "bandwidth" knowledge of results (KR), given only if the subject's response is outside of a certain movement-time bandwidth, on learning and performance of a rapid elbow-flexion movement was examined. Subjects were randomly assigned to one of three feedback groups, a 5% bandwidth group (BW5), a 10% bandwidth group (BW10), or a control group (KR), who received knowledge of results on every trial. Subjects moved a light, horizontal, aluminum lever through 60 degrees in 200 msec., for 100 acquisition trials with KR given depending on group and 25 transfer trials without KR (transfer phase). Although the subjects in the BW10 group received knowledge of results fewer times during acquisition, they showed less within-subject variability than the BW5 and KR groups on the transfer test which suggests that giving KR about a relatively large bandwidth enhances movement consistency.