Prospective Cohort Study

In order to stimulate further adaptation toward specific training goals, progressive resistance training (RT) protocols are necessary The optimal characteristics of strength-specific programs include the use of concentric (CON), eccentric (ECC), and isometric muscle actions and the performance of bilateral and unilateral single- and multiple-joint exercises In addition, it is recommended that strength programs sequence exercises to optimize the preservation of exercise intensity (large before small muscle group exercises, multiple-joint exercises before single-joint exercises, and higher-intensity before lower-intensity exercises) For novice (untrained individuals with no RT experience or who have not trained for several years) training, it is recommended that loads correspond to a repetition range of an 8-12 repetition maximum (RM) For intermediate (individuals with approximately 6 months of consistent RT experience) to advanced (individuals with years of RT experience) training, it is recommended that individuals use a wider loading range from 1 to 12 RM in a periodized fashion with eventual emphasis on heavy loading (1-6 RM) using 3- to 5-min rest periods between sets performed at a moderate contraction velocity (1-2 s CON; 1-2 s ECC) When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number The recommendation for training frequency is 2-3 d·wk -1 for novice training, 3-4 d·wk -1 for intermediate training, and 4-5 d·wk -1 for advanced training Similar program designs are recommended for hypertrophy training with respect to exercise selection and frequency For loading, it is recommended that loads corresponding to 1-12 RM be used in periodized fashion with emphasis on the 6-12 RM zone using 1- to 2-min rest periods between sets at a moderate velocity Higher volume, multiple-set programs are recommended for maximizing hypertrophy Progression in power training entails two general loading strategies: 1) strength training and 2) use of light loads (0-60% of 1 RM for lower body exercises; 30-60% of 1 RM for upper body exercises) performed at a fast contraction velocity with 3-5 min of rest between sets for multiple sets per exercise (three to five sets) It is also recommended that emphasis be placed on multiple-joint exercises especially those involving the total body For local muscular endurance training, it is recommended that light to moderate loads (40-60% of 1 RM) be performed for high repetitions (>15) using short rest periods (<90 s) In the interpretation of this position stand as with prior ones, recommendations should be applied in context and should be contingent upon an individual's target goals, physical capacity, and training status

/pdf/progression-models-in-resistance-training-for-healthy-adults-1vkvqzcu18.pdf

Progression Models in Resistance Training for Healthy Adults

Noise — random disturbances of signals — poses a fundamental problem for information processing and affects all aspects of nervous-system function. However, the nature, amount and impact of noise in the nervous system have only recently been addressed in a quantitative manner. Experimental and computational methods have shown that multiple noise sources contribute to cellular and behavioural trial-to-trial variability. We review the sources of noise in the nervous system, from the molecular to the behavioural level, and show how noise contributes to trial-to-trial variability. We highlight how noise affects neuronal networks and the principles the nervous system applies to counter detrimental effects of noise, and briefly discuss noise's potential benefits.

/pdf/noise-in-the-nervous-system-22k10mncs2.pdf

Noise in the nervous system.

羟氨苄青霉素引起大疱性类天疱疮样疹

Mini Mental State

Thank you for forwarding the letter from Dr. Wang regarding our recent publication [1] in Sports Medicine. It is nice to know that the article is generating interest. While we agree with most of the comments by Dr. Wang, the topic of the letter ‘‘On Magnetic Resonance Imaging of Intervertebral Disc Ageing’’ is peripheral to the review we wrote on exercise and the intervertebral disc (IVD). For example, while we know clinically that some people can have IVD degeneration in their 20s, this is not directly relevant to the point we were trying to get across: namely that perhaps there is a ‘‘critical period’’ in human development for the IVD in terms of when loading and exercise can have the greatest impact on lifetime IVD properties. If there is a ‘‘critical period’’ in ageing for the IVD, such as is considered [2] to be the case for bone tissue, then the exact age span still needs to be narrowed down. Furthermore, it is known [3] that vertebral body bone properties are related to IVD properties. In drafting the review, owing to the limited data in the literature on this particular point, we did not consider this issue to be currently of high priority to the topic of IVD and exercise. In another review [4] on the topic of IVD herniations in astronauts, some of my colleagues in the team suggested vertebral body bone loss during spaceflight as a potential explanation for increased IVD hydration after spaceflight and also for persistent changes in the IVD after prolonged bed rest [5]. In that particular area, it is therefore very relevant to consider vertebral bone properties. Vertebral body bone material properties (not to mention other factors such as bone marrow fat and end-plate properties, amongst other issues) will have an impact on forces transmitted to the IVD. However, owing to the paucity of data in the literature, it is currently too speculative to discuss how this might influence exercise protocols for training the IVD. Dr. Wang mentions other radiological grading schemes. We aimed to communicate magnetic resonance imaging approaches for quantifying the IVD in studies of the effect of exercise on the IVD. Our comments on grading schemes—as they apply to quantification of the IVD for studies of the effect of exercise on the IVD—apply to all grading schemes. Just the same as the standard Pfirrmann grading scheme, an eight-level modified Pfirrmann grading scheme, or a scheme including the end-plate, will be of similar limited sensitivity for use in a small sample size exercise (intervention) study. If one were to use a grading scheme as the primary outcome measure of an IVD and exercise study, then the sample size would need to be very large. One example is the cross-sectional study by Hangai et al. [6] on athletic populations and IVD degeneration where the authors had approximately 60 subjects in each group. Hence, we advise other researchers to use other approaches in studies of the effect of exercise on the IVD. Dr. Wang mentions T1rho as a method of interest for measurement of the IVD, after stating that ‘‘caution should & Daniel L. Belavý belavy@gmail.com

/pdf/authors-reply-to-wang-on-magnetic-resonance-imaging-of-4vk0sgf6xg.pdf

Authors' Reply to Wang: "On Magnetic Resonance Imaging of Intervertebral Disc Ageing".


 
 
In this paper we review what mechanisms are used to stabilize human bipedal gait. Based on mechanical reasoning, potential mechanisms to control the body center of mass trajectory are modulation of foot placement, stance leg control consisting of modulation of ankle moments and push-off forces, and modulations of the body’s angular momentum. The first two mechanisms and especially the first are dominant in controlling center of mass accelerations during gait, while angular momentum control plays a lesser role, but may be important to control body alignment and orientation. The same control mechanisms stabilize both steady-state and perturbed gait in both the mediolateral and antero-posterior directions. Control is at least in part active and is affected by proprioceptive, visual and vestibular information. Results support that this reflects a feedback process in which sensory information is used to obtain an estimate of the center of mass state based on which foot placement and ankle moments are modulated. These active feedback mechanisms suggest training approaches for populations at risk of falling, such as augmenting their effective use by means of augmented feedback, or using their complementary nature to train one mechanism by constraining the other mechanisms. 
 
 


Mechanisms that stabilize human walking

Background: Pain and dysfunction of the shoulder complex are commonly found physiotherapy practice. These musculoskeletal abnormalities are related to instability and inadequate kinematic function, that depend on the integrity of the muscle tissues. Thus, to enhance the results of exercise therapies, and prevent and attenuate pain and dynfunction, the use of oscillatory pole has been implemented in clinical practice. Objectives: The purpose of this study was to analyze the electromyographic (EMG) activity of shoulder stabilizing muscles during exercises performed with an oscillatory and a non-oscillatory pole. Methods: Twelve female volunteers, aged 20.4 years±1.9, participated in this study. EMG data were collected from upper trapezius (UT), lower trapezius (LT) and middle deltoid (MD) during three different exercises with an oscillatory and a non-oscillatory pole. The EMG signals were analyzed in the time domain through the calculation of Root Mean Square (RMS). The RMS values were normalized by the peak value obtained over all trials for each muscle. Statistical analysis was performed with repeated measures ANOVA and post-hoc of Bonferroni tests. Results: The EMG activity of UT, LT and MD muscles were significantly higher with the oscillatory pole than the non-oscillatory pole (all p<0,001). There were no significant differences in the activation of these muscles between exercises. Conclusion: The results of the present study indicated that the oscillatory pole does require higher activation of the shoulder muscles and therefore, may be useful in the training of the shoulder complex.

/pdf/electromyographic-activity-of-shoulder-muscles-during-393zc17sz3.pdf

Electromyographic activity of shoulder muscles during exercises performed with oscillatory and non-oscillatory poles Atividade eletromiográfi ca dos músculos do ombro durante exercícios executados com hastes oscilatória e não oscilatória

Jaap H. van Dieën

Papers

Authors' Reply to Wang: "On Magnetic Resonance Imaging of Intervertebral Disc Ageing".

Mechanisms that stabilize human walking

Electromyographic activity of shoulder muscles during exercises performed with oscillatory and non-oscillatory poles Atividade eletromiográfi ca dos músculos do ombro durante exercícios executados com hastes oscilatória e não oscilatória

forelimb: acute effects of coactivation Synergistic and antagonistic interactions in the rat

contractionmaintaining arm position during a fatiguing Activation among the elbow flexor muscles differs