Modern paradigms of motor control and rehabilitation are analyzed in the paper. Two main paradigms, i. e. computational approach and dynamical system approach are engaged in rivalry in motor control ...and learning research at present. From the standpoint of computational paradigm the principal mechanism of motor control and learning consists in the ability of the brain “to calculate” (acting as some kind of biological computer). According to the paradigm of dynamical systems the mechanism of motor control is time dependent. In other words, it can be different each time. The main principles of motor control and properties of movements are given considerable attention in the paper. Besides, modern methods of motor rehabilitation after stroke are emphasized in the paper. Fitting of neuroprosthesis and restoration of damaged neural cells are significant maiden steps in modern science. The scientists are engaged in search for: a) constraining such mechanism prosthesis that would submit to the efforts of human will and b) restoring neural cells damaged because of the brain stroke suffered.Keywords: motor control, rehabilitation, stroke.
Physical exercise has emerged as an alternative treatment for patients with depressive disorder. Recent animal studies show that exercise protects from depression by increased skeletal muscle ...kynurenine aminotransferase (KAT) expression which shifts the kynurenine metabolism away from the neurotoxic kynurenine (KYN) to the production of kynurenic acid (KYNA). In the present study, we investigated the effect of exercise on kynurenine metabolism in humans. KAT gene and protein expression was increased in the muscles of endurance-trained subjects compared with untrained subjects. Endurance exercise caused an increase in plasma KYNA within the first hour after exercise. In contrast, a bout of high-intensity eccentric exercise did not lead to increased plasma KYNA concentration. Our results show that regular endurance exercise causes adaptations in kynurenine metabolism which can have implications for exercise recommendations for patients with depressive disorder.
High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance ...athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca²⁺ release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca²⁺ leak at rest, and depressed force production due to impaired SR Ca²⁺ release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca²⁺-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group.
Increased production of reactive oxygen/nitrogen species (ROS) and impaired cellular Ca2+ handling are implicated in the prolonged low‐frequency force depression (PLFFD) observed in skeletal muscle ...after both metabolically and mechanically demanding exercise. Metabolically demanding high‐intensity exercise can induce PLFFD accompanied by ROS‐dependent fragmentation of the sarcoplasmic reticulum Ca2+ release channels, the ryanodine receptor 1s (RyR1s). We tested whether similar changes occur after mechanically demanding eccentric contractions. Human subjects performed 100 repeated drop jumps, which require eccentric knee extensor contractions upon landing. This exercise caused a major PLFFD, such that maximum voluntary and electrically evoked forces did not recover within 24 h. Drop jumps induced only minor signs of increased ROS, and RyR1 fragmentation was observed in only 3 of 7 elderly subjects. Also, isolated mouse muscle preparations exposed to drop‐jump–mimicking eccentric contractions showed neither signs of increased ROS nor RyR1 fragmentation. Still, the free cytosolic Ca2+ during tetanic contractions was decreased by ~15% 1 h after contractions, which can explain the exaggerated force decrease at low‐stimulation frequencies but not the major frequency‐independent force depression. In conclusion, PLFFD caused by mechanically demanding eccentric contractions does not involve any major increase in ROS or RyR1 fragmentation.—Kamandulis, S., de Souza Leite, F., Hernandez, A., Katz, A., Brazaitis, M., Bruton, J. D., Venckunas, T., Masiulis, N., Mickeviciene, D., Eimantas, N., Subocius, A., Rassier, D. E., Skurvydas, A., Ivarsson, N., Westerblad, H. Prolonged force depression after mechanically demanding contractions is largely independent of Ca2+ and reactive oxygen species. FASEB J. 31, 4809–4820 (2017). www.fasebj.org
The aim of our study was to determine how six mood indicators (vigour, fatigue, depression, anger, confusion, tension) depend on moderate to vigorous physical activity, walking time and sedentary ...time at work, after working hours and during leisure time, in men and women of different age groups.
A total of 1,140 individuals aged 18 to 64 years participated in the study. The participants were enrolled in this cross-sectional survey using a snowball sampling method. An online questionnaire was shared through popular social networks and emails within the period October 2019 to June 2020. Mood responses were assessed using The Brunel Mood Scale-LTU. Physical activity was assessed using the long International Physical Activity Questionnaire. Descriptive analysis, a two-way analysis of variance, and linear regression analysis were used to interpret the data.
The survey results showed that vigour and fatigue correlated significantly only with leisure-time moderate to vigorous physical activity. The present results show a significant positive correlation between women and men moods and leisure-time moderate to vigorous physical activity, the length of time walking to work and back home, and negative correlation between moods and leisure-time sedentary behaviour. However, there was no significant correlation between moods and work-related moderate to vigorous physical activity and household moderate to vigorous physical activity, walking at work, and sitting duration at work.
This study provides theoretical implications of the physical activity paradox, justifying the benefits of moderate to vigorous physical activity practiced in different circumstances. According to the regression analysis, exercising men in all age groups moved the most (had a higher moderate to vigorous physical activity level) during leisure time, the highest work-related moderate to vigorous physical activity was observed in men and women with lower education, and the highest household moderate to vigorous physical activity was observed in older age men and women living in rural areas. Clinicians and leaders at all levels of health care should consider the greater importance of leisure-time physical activity for mental health when choosing the most targeted physical activity recommendations for mood profile improvement in men and women of different age groups.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose To compare the concomitant treatment of articular cartilage damage in the medial femoral condyle with osteochondral autologous transplantation (OAT), microfracture, or debridement procedures ...at the time of anterior cruciate ligament (ACL) reconstruction. Methods Between 2006 and 2009, 102 patients with a mean age of 34.1 years and with an ACL rupture and articular cartilage damage in the medial femoral condyle of the knee were randomized to undergo OAT, microfractures, or debridement at the time of ACL reconstruction. A matched control group was included, comprising 34 patients with intact articular cartilage at the time of ACL reconstruction. There were 34 patients in the OAT-ACL group, 34 in the microfracture (MF)–ACL group, 34 in the debridement (D)–ACL group, and 34 in the control group with intact articular cartilage (IAC-ACL group). The mean time from ACL injury to operation was 19.32 ± 3.43 months, and the mean follow-up was 36.1 months (range, 34 to 37 months). Patients were evaluated with the International Knee Documentation Committee (IKDC) score, Tegner activity score, and clinical assessment. Results Of 102 patients, 97 (95%) were available for the final follow-up. According to the subjective IKDC score, all 4 groups fared significantly better at the 3-year follow-up than preoperatively ( P < .005). The OAT-ACL group’s IKDC subjective knee evaluation was significantly better than that of the MF-ACL group ( P = .024) and D-ACL group ( P = .018). However, the IKDC subjective score of the IAC-ACL group was significantly better than the OAT-ACL group’s IKDC evaluation ( P = .043). There was no significant difference between the MF-ACL and D-ACL groups’ IKDC subjective scores ( P = .058). Evaluation of manual pivot-shift knee laxity according to the IKDC knee examination form showed similar findings for the 4 groups immediately postoperatively and at 3-year follow-up, and the findings were rated as normal or nearly normal (IKDC grade A or B) in 29 of 33 patients (88%) in the OAT-ACL group, 28 of 32 patients (88%) in the MF-ACL group, 27 of 32 patients (84%) in the D-ACL group, and 31 of 34 patients (91%) in the IAC-ACL group. Conclusions Our study shows that intact articular cartilage during ACL reconstruction yields more favorable IKDC subjective scores compared with any other articular cartilage surgery type. However, if an articular defect is present, the subjective IKDC scores are significantly better for OAT versus microfracture or debridement after a mean period of 3 years. Anterior knee stability results were not significantly affected by the different articular cartilage treatment methods. Level of Evidence Level II, prospective comparative study.
Here, we address the question of why some people have a greater chance of surviving and/or better resistance to cold-related-injuries in prolonged exposure to acute cold environments than do others, ...despite similar physical characteristics. The main aim of this study was to compare physiological and psychological reactions between people who exhibited fast cooling (FC; n = 20) or slow cooling (SC; n = 20) responses to cold water immersion. Individuals in whom the T(re) decreased to a set point of 35.5 °C before the end of the 170-min cooling time were indicated as the FC group; individuals in whom the T(re) did not decrease to the set point of 35.5 °C before the end of the 170-min cooling time were classified as the SC group. Cold stress was induced using intermittent immersion in bath water at 14 °C. Motor (spinal and supraspinal reflexes, voluntary and electrically induced skeletal muscle contraction force) and cognitive (executive function, short term memory, short term spatial recognition) performance, immune variables (neutrophils, leucocytes, lymphocytes, monocytes, IL-6, TNF-α), markers of hypothalamic-pituitary-adrenal axis activity (cortisol, corticosterone) and autonomic nervous system activity (epinephrine, norepinephrine) were monitored. The data obtained in this study suggest that the response of the FC group to cooling vs the SC group response was more likely an insulative-hypothermic response and that the SC vs the FC group displayed a metabolic-insulative response. The observations that an exposure time to 14 °C cold water--which was nearly twice as short (96-min vs 170-min) with a greater rectal temperature decrease (35.5 °C vs 36.2 °C) in the FC group compared with the SC group--induces similar responses of motor, cognitive, and blood stress markers were novel. The most important finding is that subjects with a lower cold-strain-index (SC group) showed stimulation of some markers of innate immunity and suppression of markers of specific immunity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objectives. The acute fasting-induced cardiovascular autonomic response and its effect on cognition and mood remain debatable. Thus, the main purpose of this study was to estimate the effect of a 48 ...h, zero-calorie diet on autonomic function, brain activity, cognition, and mood in amateur weight lifters. Methods. Nine participants completed a 48 h, zero-calorie diet program. Cardiovascular autonomic function, resting frontal brain activity, cognitive performance, and mood were evaluated before and after fasting. Results. Fasting decreased (p<0.05) weight, heart rate, and systolic blood pressure, whereas no changes were evident regarding any of the measured heart rate variability indices. Fasting decreased (p<0.05) the concentration of oxygenated hemoglobin and improved (p<0.05) mental flexibility and shifting set, whereas no changes were observed in working memory, visuospatial discrimination, and spatial orientation ability. Fasting also increased (p<0.05) anger, whereas other mood states were not affected by it. Conclusions. 48 h fasting resulted in higher parasympathetic activity and decreased resting frontal brain activity, increased anger, and improved prefrontal-cortex-related cognitive functions, such as mental flexibility and set shifting, in amateur weight lifters. In contrast, hippocampus-related cognitive functions were not affected by it.
The time course of physiological and psychological markers during cold acclimation (CA) was explored. The experiment included 17 controlled (i.e., until the rectal temperature reached 35.5°C or 170 ...min had elapsed; for the CA-17 session, the subjects (n = 14) were immersed in water for the same amount of time as that used in the CA-1 session) head-out water immersions at a temperature of 14°C over 20 days. The data obtained in this study suggest that the subjects exhibited a thermoregulatory shift from peripheral-to-central to solely central input thermoregulation, as well as from shivering to non-shivering thermogenesis throughout the CA. In the first six CA sessions, a hypothermic type of acclimation was found; further CA (CA-7 to CA-16) led to a transitional shift to a hypothermic-insulative type of acclimation. Interestingly, when the subjects were immersed in water for the same time as that used in the CA-1 session (CA-17), the CA led to a hypothermic type of acclimation. The presence of a metabolic type of thermogenesis was evident only under thermoneutral conditions. Cold-water immersion decreased the concentration of cold-stress markers, reduced the activity of the innate immune system, suppressed specific immunity to a lesser degree and yielded less discomfort and cold sensation. We found a negative correlation between body mass index and Δ metabolic heat production before and after CA.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose
The aim of this study was to follow post-activation potentiation (PAP), low-frequency fatigue (LFF), metabolic-induced fatigue and post-contractile depression (PCD) in response to different ...isometric muscle contraction modalities.
Methods
Young healthy men (
N
= 120) were randomly assigned to one of ten exercise modality groups which differed in contraction duration (5–60 s), activation pattern (intermittent or continuous contractions), activation mode (voluntary or stimulated), and intensity maximal or submaximal (50%). Isometric maximal voluntary contraction (MVC), and electrically induced knee extension torque were measured at baseline and at regular intervals for 60 min after exercise.
Results
Muscle contraction modalities involving 5 s MVC were the most effective for PAP, whereas the lowest PAP effectiveness was found after the 12 × 5-MVC modality. After all of the 5–15 s MVC and 6 × 5-MVC protocols, the potentiation of the twitch rate was significantly higher than that recorded after continuous 30–60 s protocols (
P
< 0.001). Tetanic maximal torque (100 Hz) potentiation occurred 5 min after 15–30 s repetitive MVC modalities and after modality involving 15 electrical stimuli (
P
< 0.05).
Conclusions
The findings demonstrate that post-activation potentiation was most effective after brief duration continuous and repetitive MVC protocols. To understand the resultant warm-up of motor performance, it is necessary to recognize the coexistence of muscle PAP, tetanic maximal force potentiation, rapid recovery of metabolic muscle, and central muscle activation processes, as well as prolonged LFF and prolonged PCD.
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