Developmental changes in the response to obstacles during prehension

Adults are proficient at reaching to grasp objects of interest in a cluttered workspace. The issue of concern, obstacle avoidance, was studied in 3 groups of young children aged 11-12, 9-10, and 7-8 years (n = 6 in each) and in 6 adults aged 18-24 years. Adults slowed their movements and decreased their maximum grip aperture when an obstacle was positioned close to a target object (the effect declined as the distance between target and obstacle increased). The children showed the same pattern, but the magnitude of the effect was quite different. In contrast to the adults, the obstacle continued to have a large effect when it was some distance from the target (and provided no physical obstruction to movement).

A simple and unified approach to human voluntary movements

In his provocative article, F. Mechsner (2004) advances the thesis that human voluntary movements are subject to "psychological" or "perceptual -cognitive" control and are thus organized "without regard to efferent patterns" (p. 355). Rather than considering in detail the experiments that he proffered by way of support, the present author discusses the degree to which that supposition has appeal on the grounds of simplicity and is defined in terms that are compatible with a unified science.

Early alterations in serum creatine kinase and total cholesterol following high intensity eccentric muscle actions

Aim. The purpose of this experiment was to assess the levels of muscle soreness, serum total cholesterol (TC) and creatine kinase (CK) in the first 48 hours following fatiguing eccentric exercise performed with the triceps brachii.

The effect of volition on the stability of bimanual coordination

The authors investigated how the intention to passively perform a behavior and the intention to persist with a behavior impact upon the spatial and temporal properties of bimanual coordination. Participants (N = 30) were asked to perform a bimanual coordination task that demanded the continuous rhythmic extension-flexion of the wrists. The frequency of movement was scaled by an auditory metronome beat from 1.5 Hz, increasing to 3.25 Hz in .25-Hz increments. The task was further defined by the requirement that the movements be performed initially in a prescribed pattern of coordination (in-phase or antiphase) while the participants assumed one of two different intentional states: stay with the prescribed pattern should it become unstable or do not intervene should the pattern begin to change. Transitions away from the initially prescribed pattern were observed only in trials conducted in the antiphase mode of coordination. The time at which the antiphase pattern of coordination became unstable was not found to be influenced by the intentional state. In addition, the do-not-intervene set led to a switch to an in-phase pattern of coordination whereas the stay set led to phase wandering. Those findings are discussed within the framework of a dynamic account of bimanual coordination.

Neural adaptations to resistance training - Implications for movement control

It has long been believed that resistance training is accompanied by changes within the nervous system that play an important role in the development of strength. Many elements of the nervous system exhibit the potential for adaptation in response to resistance training, including supraspinal centres, descending neural tracts, spinal circuitry and the motor end plate connections between motoneurons and muscle fibres. Yet the specific sites of adaptation along the neuraxis have seldom been identified experimentally, and much of the evidence for neural adaptations following resistance training remains indirect. As a consequence of this current lack of knowledge, there exists uncertainty regarding the manner in which resistance training impacts upon the control and execution of functional movements. We aim to demonstrate that resistance training is likely to cause adaptations to many neural elements that are involved in the control of movement, and is therefore likely to affect movement execution during a wide range of tasks.

Cardiovascular disease risk profiles among 'healthy' siblings of patients with early-onset cardiovascular disease:Application of the new SCORE system

BACKGROUND: Cardiovascular disease (CVD) occurs more frequently in individuals with a family history of premature CVD. Within families the demographics of CVD are poorly described. DESIGN: We examined the risk estimation based on the Systematic Coronary Risk Evaluation (SCORE) system and the Joint British Guidelines (JBG) for older unaffected siblings of patients with premature CVD (onset ≤55 years for men and ≤60 years for women). METHODS: Between August 1999 and November 2003 laboratory and demographic details were collected on probands with early-onset CVD and their older unaffected siblings. Siblings were screened for clinically overt CVD by a standard questionnaire and 12-lead electrocardiogram (ECG). RESULTS: A total of 790 siblings was identified and full demographic details were available for 645. The following siblings were excluded: 41 with known diabetes mellitus; seven with random plasma glucose of 11.1 mmol/l or greater; and eight with ischaemic ECG. Data were analysed for 589 siblings from 405 families. The mean age was 55.0 years, 43.1% were men and 28.7% were smokers. The mean total serum cholesterol was 5.8 mmol/l and hypertension was present in 49.4%. Using the SCORE system, when projected to age 60 years, 181 men (71.3%) and 67 women (20.0%) would be eligible for risk factor modification. Using JBG with a 10-year risk of 20% or greater, 42 men (16.5%) and four women (1.2%) would be targeted. CONCLUSIONS: Large numbers of these asymptomatic individuals meet both European and British guidelines for the primary prevention of CVD and should be targeted for risk factor modification. The prevalence of individuals defined as eligible for treatment is much higher when using the SCORE system. © 2007 European Society of Cardiology.

LDL particle size in habitual exercisers, lean sedentary men and abdominally obese sedentary men

Habitual exercisers enjoy considerable protection from coronary heart disease (CHD). Often, however, only modest differences in traditional CHD risk factors are apparent between habitual exercisers and their sedentary counterparts. For this reason, there is increasing interest in novel predictors of CHD, such as a preponderance of small, dense low-density lipoprotein (LDL) particles. Polyacrylamide gel electrophoresis was used to separate lipoprotein subfractions in 32 lean exercisers, 36 lean sedentary men and 21 obese sedentary men aged 30-45 years. Well-validated equations were used to determine LDL concentration and peak particle diameter. Waist girth was used to identify lean (<100 cm) and obese ( >= 100cm) individuals. LDL concentration was lower in lean exercisers than in lean sedentary men (2.64 +/- 0.44 vs. 3.76 +/- 0.79 mmol.l(-1), p <0.001), suggesting that habitual exercise influences this risk factor. In contrast, there were no significant differences in LDL peak particle diameter between lean exercisers, lean sedentary men and obese sedentary men (27.92 +/- 0.67, 28.09 +/- 0.62 and 27.77 +/- 0.77 nm, respectively). In multiple linear regression analysis, triglyceride concentration was the only significant predictor of LDL PPD. These data suggest that habitual exercise influences LDL concentration but does not influence LDL particle size in men aged 30-45 years.