Increased time-delay in the neuromuscular system caused by neurological disorders, concussions, or advancing age is an important factor contributing to balance loss (Chagdes et al., 2013, 2016a,b). We present the design and fabrication of an active balance board system that allows for a systematic study of stiffness and time-delay induced instabilities in standing posture. Although current commercial balance boards allow for variable stiffness, they do not allow for manipulation of time-delay. Having two controllable parameters can more accurately determine the cause of balance deficiencies, and allows us to induce instabilities even in healthy populations. An inverted pendulum model of human posture on such an active balance board predicts that reduced board rotational stiffness destabilizes upright posture through board tipping, and limit cycle oscillations about the upright position emerge as feedback time-delay is increased. We validate these two mechanisms of instability on the designed balance board, showing that rotational stiffness and board time-delay induced the predicted postural instabilities in healthy, young adults. Although current commercial balance boards utilize control of rotational stiffness, real-time control of both stiffness and time-delay on an active balance board is a novel and innovative manipulation to reveal balance deficiencies and potentially improve individualized balance training by targeting multiple dimensions contributing to standing balance. 相似文献
Light and dark phase training may influences rodents’ physiologic parameters because these animals have nocturnal habits. Thus, we verify the effects of the training in different photoperiods on metabolism and corporal composition of rats. Eighteen rats were divided into three groups – G1: non-trained; G2: trained in the light phase; G3: trained in the dark phase. Rats were allowed to swim for 60 min, five times per week during six weeks. Trained animals presented a smaller weight gain and fat percentage in carcass. Rats of G3 increased gastrocnemius relative weight. The adipocyte diameter of G3 rats was smaller than the other groups. The levels of the total cholesterol, low-density proteins, and triacylglycerols were decreased in animals of G2 while the glycemia was increased. Training in light phase provided more alterations in the blood biochemical profile while the training in the dark increased the gastrocnemius weight and decreased the diameter of the adipocyte. 相似文献
Retinal prostheses aim at restoring visual perception in blind patients affected by retinal diseases leading to the loss of photoreceptors, such as age-related macular degeneration or retinitis pigmentosa. Recent clinical trials have demonstrated the feasibility of this approach for restoring useful vision. Despite a limited number of electrodes (60), and therefore of pixels, some patients were able to read words and to recognize high-contrast objects. Face recognition and independent locomotion in unknown urban environments imply technological breakthroughs to increase the number and density of electrodes. This review presents recent clinical results and discusses future solutions to answer the major technological challenges. 相似文献
The TGF-β1-Smad pathway is a well-known negative regulator of muscle growth; however, its potential role in resistance training-induced muscle hypertrophy is not clear. The present study proposed to determine whether and how this pathway may be involved in resistance training-induced muscle hypertrophy. Skeletal muscle samples were collected from the control, trained (RT), control + SB431542 (CITGF), and trained + SB431542 (RTITGF) animals following 3, 5, and 8 weeks of resistance training. Inhibition of the TGF-β1-Smad pathway by SB431542 augmented muscle satellite cells activation, upregulated Akt/mTOR/S6K1 pathway, and attenuated FOXO1 and FOXO3a expression in the CITGF group (all p < .01), thereby causing significant muscle hypertrophy in animals from the CITGF. Resistance training significantly decreased muscle TGF-β1 expression and Smad3 (P-Smad3S423/425) phosphorylation at COOH-terminal residues, augmented Smad2 (P-Smad2-LS245/250/255) and Smad3 (P-Smad3-LSer208) phosphorylation levels at linker sites (all p < .01), and led to a muscle hypertrophy which was unaffected by SB431542, suggesting that the TGF-β1-Smad signaling pathway is involved in resistance training-induced muscle hypertrophy. The effects of inhibiting the TGF-β1-Smad signaling pathway were not additive to the resistance training effects on FOXO1 and FOXO3a expression, muscle satellite cells activation, and the Akt/mTOR/S6K1 pathway. Resistance training effect of satellite cell differentiation was independent of the TGF-β1-Smad signaling pathway. These results suggested that the effect of the TGF-β1-Smad signaling pathway on resistance training-induced muscle hypertrophy can be attributed mainly to its diminished inhibitory effects on satellite cell activation and protein synthesis. Suppressed P-Smad3S423/425 and enhanced P-Smad2-LS245/250/255 and P-Smad3-LSer208 are the molecular mechanisms that link the TGF-β1-Smad signaling pathway to resistance training-induced muscle hypertrophy. 相似文献
Overpopulation and deficient management of the worlds coastlines have seriously degraded beaches and coastal dunes, which are environments that provide valuable ecosystem services to society. The need to restore these ecosystems is increasingly urgent; however, this is a complex task since variables that differ widely (i.e. ecological, geomorphological and socio-economic) must all be taken into consideration. The present study proposes an index in the form of a weighted checklist named the “ReDune” Index (Restoration of coastal Dunes). This index allows decision makers and non-specialized professionals with some level of understanding of coastal dynamics to decide whether coastal dunes (foredunes) require and can be restored. Furthermore, in cases where more than one coastal dune system is to be evaluated, the index can distinguish which are in the most urgent need of restoration. The index consists of four sections: the first evaluates the degree of perturbation. The second determines the presence of endogenous and exogenous stress factors that may compromise the long-term stability of the restoration. The third section is focused on highlighting the abiotic and biotic elements that may facilitate restoration. Finally, the fourth section contributes to the identification of interests related to the conservation of the site and the provision of ecosystem services. The index was tested on 31 locations along the Gulf of Mexico, with differing sedimentary, ecological and human pressure characteristics and clearly distinguished between locations where restoration is urgent from those where it is not. This index can be applied on any foredune. 相似文献
Although it has been reported that strengthening exercise in stroke patients is beneficial for their motor recovery, there is little evidence about which exercise method is the better option. The purpose of this study was to compare isotonic and isokinetic exercise by surface electromyography (EMG) analysis using standardized methods.Nine stroke patients performed three sets of isotonic elbow extensions at 30% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic elbow extensions with standardization of mean angular velocity and the total amount of work for each matched set in two strengthening modes. All exercises were done by using 1-DoF planner robot to regulate exact resistive torque and speed. Surface electromyographic activity of eight muscles in the hemiplegic shoulder and elbow was recorded. Normalized root mean square (RMS) values and co-contraction index (CCI) were used for the analysis.The isokinetic mode was shown to activate the agonists of elbow extension more efficiently than the isotonic mode (normalized RMS for pooled triceps: 96.0 ± 17.0 (2nd), 87.8 ± 14.4 (3rd) in isokinetic, 80.9 ± 11.0 (2nd), 81.6 ± 12.4 (3rd) in isotonic contraction, F[1, 8] = 11.168; P = 0.010) without increasing the co-contraction of muscle pairs, implicating spasticity or synergy. 相似文献
1. 1. In this short review, previous studies regarding the modeling of lactate (La) response to exercise and its application to endurance training have been summarized.
2. 2. Additionally the result of a recent study by the present authors are shown.
3. 3. Several models for La response to step and ramp exercise are already proposed and deductions derived from them are used for practical purposes such as the prediction of race performance in middle-and long-distance runners as well as for construction of their training regimens.
4. 4. Only a limited number of models however have tried to quantify whole body La kinetics to exercise in humans concomitantly with describing physiological mechanisms underlying the observed phenomenon.
5. 5. In a recent study described further in this paper a 2 compartment model was used for the purpose of clarifying the current “La production vs degradation” controversy during La adaptation to training.
6. 6. It was determined from this investigation that the La metabolic clearance rate during recovery is enhanced by the endurance training.
7. 7. This is in accordance with another recent observation of an increased La metabolic clearance rate at high absolute work rates and all relative work rates during exercise.