Neurophysiological Adaptations to Resistance Training and Repetitive Grasping

Perhaps the most prominent feature of the central nervous system is its ability to respond to experience and its environment. Understanding the processes and mechanisms that govern adaptive behavior provides insights into its plastic nature. Capitalizing on this plasticity is of critical importance in response to injury and recovery: 35, 106), and the importance of its promotion is increasingly recognized by rehabilitation scientists. Neurophysiological techniques permitting study of cortical function in vivo may play a significant role in validating exercise interventions and disease management approaches: 14). It may be possible that with these advances we may better understand the relationship between brain function and therapeutic approaches. For this purpose, we present data on both cumulative and acute effects of motor training to better understand adaptive processes. Neural adaptations accompany resistance training, but current evidence regarding the nature of these adaptations is best characterized as indirect, particularly with respect to adaptation within central or supraspinal centers: 56). To this end, we recorded movement-related cortical potentials: MRCP), i.e. electroencephalography: EEG)-derived event-related potentials, in healthy adults prior to and following a program of lower body resistance training. The cumulative effects of nine progressive training sessions resulted in attenuation of relative MRCP amplitudes. We interpreted these findings in terms of neural efficiency such that for the same pre-training load, central effort is diminished post-training. These data demonstrate the impact of cumulative motor training sessions in fostering a reduction in the level of cortical motor activation. Such a program may be of a particular utility for individuals with limited motor reserves such as those with Parkinson disease: PD). Although cumulative effects may foster a more efficient cortical network, the acute demands of a training session have received less attention. It is reasonable to assume that the reverse might be expected: i.e. augmented amplitude) during a motor training session, much like the muscular system is taxed during resistance training exercise. At the level of the cortex, neural activity was studied by recording the MRCP during 150 repetitive handgrip contractions at a high intensity. The goal of this work was to examine whether central adaptive processes used to maintain task performance vary as a function of age or PD. We found that for healthy young adults, augmented activation of motor cortical centers is responsible for maintaining performance. However, this was not observed for older adults with and without PD, where minimal changes in cortical activity were observed over the duration of the protocol. Our findings suggest that older adults and those with PD may rely on alternative mechanisms: i.e. mobilization of additional cortical and subcortical structures) to maintain task performance as compared to increasing activity locally as seen with younger adults. Taken together, our work further supports the adaptable nature of the central nervous system. We note in passing the utility of the MRCP paradigm for observing such effects

Exploring the Impact of and Perceptions about Interactive, Self-Explaining Environments in Molecular-Level Animations

This mixed-method study investigates the effects of interactivity in animations of a molecular-level process and explores perceptions about the animated learning tool used. Treatments were based on principles of cognitive psychology designed to study the main effects of treatment and spatial ability and their interaction. Results with students (n = 189) showed that science majors scored higher than non-science majors in retention measures (i.e., structure and function) but not in transfer. Significant main effects were found for treatment in function questions and spatial ability in structure questions. There was a significant interaction between treatment and spatial ability in structure questions. Additionally, in this study participants believed the key and the motion of ions and molecules were the most helpful parts of the animation. This study shows that students perceive the animations as being supportive of their learning, suggesting that animations do have a role in science classrooms

Resistance training induces supraspinal adaptations: Evidence from movement-related cortical potentials

Early effects of a resistance training program include neural adaptations at multiple levels of the neuraxis, but direct evidence of central changes is lacking. Plasticity exhibited by multiple supraspinal centers following training may alter slow negative electroencephalographic activity, referred to as movement-related cortical potentials (MRCP). The purpose of this study was to determine whether MRCPs are altered in response to resistance training. Eleven healthy participants (24.6 ± 3.5 years) performed 3 weeks of explosive unilateral leg extensor resistance training. MRCP were assessed during 60 self-paced leg extensions against a constant nominal load before and after training. Resistance training was effective (P < 0.001) in increasing leg extensor peak force (+22%), rate of force production (+32%) as well as muscle activity (iEMG; +47%, P < 0.05). These changes were accompanied by several MRCP effects. Following training, MRCP amplitude was attenuated at several scalp sites overlying motor-related cortical areas (P < 0.05), and the onset of MRCP at the vertex was 28% (561 ms) earlier. In conclusion, the 3-week training protocol in the present study elicited significant strength gains which were accompanied by neural adaptations at the level of the cortex. We interpret our findings of attenuated cortical demand for submaximal voluntary movement as evidence for enhanced neural economy as a result of resistance training

The consideration of post-exercise impact on SCAT3 scores in athletes immediately following a head injury

Examine effects of high-intensity exercise and physical impacts during rugby match on self-report symptoms in The Sport Concussion Assessment Tool (SCAT3), and its ability to differentiate head-injured players from controls. Methods: Symptoms were assessed immediately following completion of a rugby match (median 60 minutes). Players removed from the match for assessment due to a head hit were classified as head injured. Controls completed match without head hit. Results: 209 players (67 female; 33 ± 13 years) participated with 80 experiencing a head injury. Symptom severity was significantly greater in head injured (26.2 ± 17.6) compared with controls (8.9 ± 11.5, P 16 symptom severity, misclassifying them as suspected concussion. There were no significant sex differences. Factor analysis produced four symptom clusters of which Headache was most discriminatory between the head injured (median = 1.7) and controls (median = 0.0). Conclusion: These findings demonstrate that exercise and contact during a game affect symptom assessment, increasing the likelihood of misclassifying players with suspected concussion. Factor characterization of symptoms associated with head injury using an exercised comparison group provides more useful discrimination. These results highlight the necessity for objective measures to diagnose concussions outside of symptom self-report

A Retrospective Cohort Study of U.S. Service Members Returning from Afghanistan and Iraq: Is Physical Health Worsening Over time?

Background: High rates of mental health disorders have been reported in veterans returning from deployment to Afghanistan (Operation Enduring Freedom: OEF) and Iraq (Operation Iraqi Freedom: OIF); however, less is known about physical health functioning and its temporal course post-deployment. Therefore, our goal is to study physical health functioning in OEF/OIF veterans after deployment. Methods: We analyzed self-reported physical health functioning as physical component summary (PCS) scores on the Veterans version of the Short Form 36 health survey in 679 OEF/OIF veterans clinically evaluated at a post-deployment health clinic. Veterans were stratified into four groups based on time post-deployment: (1Yr) 0 – 365 days; (2Yr) 366 – 730 days; (3Yr) 731 – 1095 days; and (4Yr+) > 1095 days. To assess the possibility that our effect was specific to a treatment-seeking sample, we also analyzed PCS scores from a separate military community sample of 768 OEF/OIF veterans evaluated pre-deployment and up to one-year post-deployment. Results: In veterans evaluated at our clinic, we observed significantly lower PCS scores as time post-deployment increased (p = 0.018) after adjusting for probable post-traumatic stress disorder (PTSD). We similarly observed in our community sample that PCS scores were lower both immediately after and one year after return from deployment (p < 0.001) relative to pre-deployment PCS. Further, PCS scores obtained 1-year post-deployment were significantly lower than scores obtained immediately post-deployment (p = 0.02). Conclusion: In our clinical sample, the longer the duration between return from deployment and their visit to our clinic, the worse the Veteran’s physical health even after adjusting for PTSD. Additionally, a decline is also present in a military community sample of OEF/OIF veterans. These data suggest that, as time since deployment length increases, physical health may deteriorate for some veterans

Effect of a liquid multi-vitamin-mineral supplement on anaerobic exercise performance

This is the publisher's version, also found at http://ehis.ebscohost.com/ehost/detail?sid=10f44d64-ddff-470e-a85a-b4c63b016efa%40sessionmgr10&vid=1&hid=2&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=s3h&AN=20338872The purpose of this study was to determine if supplementation with a liquid multi-vitamin/mineral would improve anaerobic exercise performance. Fourteen resistance-trained men performed a 30-second cycle sprint and one set of squat exercise on 2 separate days before and following 8 weeks of supplementation with either a liquid multi-vitamin/ mineral or a placebo. Heart rate, perceived exertion, blood lactate, peak and mean power, and rate of fatigue were determined for all tests. No differences were noted for any variable (P > 0.05). When controlling for presupplementation values, however, a decreased rate of fatigue was noted for both exercise tests following the multi-vitamin/mineral supplementation. These data suggest that in resistance trained men consuming a nutritionally sound diet, supplementation with a liquid multi-vitamin/mineral does not favorably impact most anaerobic exercise performances. Such supplementation, however, may result in a minor decreased rate of fatigue. It appears that, in terms of improved short duration anaerobic exercise performance, supplemental micronutrients may not be efficient ergogenic agents for well-trained individuals consuming an adequate diet

Functionalization of carbon nanotubes with proteins and quantum dots in aqueous buffer solutions

We report here on a method of suspending carbon nanotubes (CNTs) in aqueous buffer solutions and functionalizing CNTs with a molecule that is ``sticky'' to proteins. The specific bifunctional molecule used in this study is 1-pyrene butanoic acid succidymidyl ester (1-pbase). We report successful protein and quantum dot functionalization of the CNTs, using 1-pbase as a linking agent

The molecular origins of the mechanical properties of fibrin

When normal blood circulation is compromised by damage to vessel walls, clots are formed at the site of injury. These clots prevent bleeding and support wound healing. To sustain such physiological functions, clots are remarkably extensible and elastic. Fibrin fibers provide the supporting framework of blood clots, and the properties of these fibers underlie the mechanical properties of clots. Recent studies, which examined individual fibrin fibers or cylindrical fibrin clots, have shown that the mechanical properties of fibrin depend on the mechanical properties of the individual fibrin monomers. Within the fibrin monomer, three structures could contribute to these properties: the coiled-coil connectors the folded globular nodules and the relatively unstructured αC regions. Experimental data suggest that each of these structures contributes. Here we review the recent work with a focus on the molecular origins of the remarkable biomechanical properties of fibrin clots