Prefrontal Cortex Activity Predicts Mental Fatigue in Young and Elderly Men During a 2 h “Go/NoGo” Task

Background: Although the effects of mental fatigue on cognitive–motor function and psychological state in young adults are well-documented, its effects in the elderly are not completely understood. The aim of this study was to estimate the effect of prolonged cognitive load on the indicators of psychological, cognitive, and motor functions.Methods: Fifteen young and 15 elderly men were asked to perform a 2 h “Go/NoGo” task. Psychological state (mood and motivation), cognitive (prefrontal cortex activity and cognitive performance), and motor (motor cortex excitability and grip strength) functions were measured before and after the task. During the 2 h task, both groups had a significantly similar increase in the number of “Incorrect NoGo” errors. Only in young men reaction time (RT) of “Incorrect NoGo” and intraindividual variability of RT of “Incorrect NoGo” significantly increased during task. After the task, handgrip strength decreased for the young men, whereas latency of motor evoked potentials prolonged both groups. Nevertheless, both groups indicated that they felt fatigue after the 2 h task; we observed that mental demand increased, whereas intrinsic motivation and mood decreased only in young men. Prolonged task decreased the switching/rest ratio of oxygenated hemoglobin for the young and the elderly men; however, greater for elderly than young men. Interestingly, the more the prefrontal cortex was activated before the 2 h task during the switching task, the fewer of “Incorrect NoGo” errors made by the young men and the greater the number of errors made by the elderly men.Conclusion: Because of the greater mental load and (possibly) greater activation of prefrontal cortex during the 2 h “Go/NoGo” task, there was greater mental and neuromuscular performance fatigue in young men than in elderly men

Šildymo ir šaldymo poveikis raumenų valingosios ir elektrostimuliacijos sukeltos jėgos kaitai

The aim of this study was to investigate the effect of heating and cooling on time course of voluntary and electrically induced muscle force variation. Material and Methods. Ten volunteers performed 50 maximal voluntary and electrically induced contractions of the knee extensors at an angle of 120 degrees under the control conditions and after passive lower body heating and cooling in the control, heating, and cooling experiments. Peak torque, torque variation, and half-relaxation time were assessed during the exercise. Results. Passive lower body heating increased muscle and core temperatures, while cooling lowered muscle temperature, but did not affect core temperature. We observed significantly lower muscle fatigue during voluntary contraction compared with electrically induced contractions. Body heating (opposite to cooling) increased involuntarily induced muscle force, but caused greater electrically induced muscle fatigue. In the middle of the exercise, the coefficient of correlation for electrically induced muscle torque decreased significantly as compared with the beginning of the exercise, while during maximal voluntary contractions, this relation for torque remained significant until the end of the exercise. Conclusion. It was shown that time course of voluntary contraction was more stable than in electrically induced contractions

The effect of moderate-intensity aerobic physical load on the body temperature and running speed in athletes and physically inactive persons

Tiesioginis galūnių pašildymas gali smarkiai paveikti raumenų jėgą ir galingumą atliekant izokinetinius pratimus. Nustatyta, kad padidėjusi raumens temperatūra pagerina dinaminio krūvio kokybę. Mūsų tyrimo tikslas buvo nustatyti neintensyvaus aerobinio fizinio krūvio poveikį sportuojančių ir aktyviai nesportuojančių asmenų kūno temperatūrai ir bėgimo greičiui. Tyrime dalyvavo dvi grupės: sportuojantys ir aktyviai nesportuojantys asmenys. Sportuojančiųjų grupę sudarė 19–22 m. vyrai (n = 6; ūgis 182,7 ± 5,1 cm; kūno masė 72 ± 6,2 kg), aktyviai nesportuojančiųjų – sveiki 20–23 m. vyrai (n = 15; ūgis 181,7 ± 6,2 cm; kūno masė 71,7 ± 8,6 kg). Tiriama buvo du kartus skirtingomis dienomis, tarp tyrimų buvo savaitės pertrauka. Testai buvo atliekami 17–18°C temperatūroje. Prieš pradedant testavimą buvo matuojama kūno temperatūra – gyvsidabrinis termometras dedamas į pažastį 5 minutėms (Dollberg et al., 2003).Pirmasis tyrimas: tiriamieji bėgo 10 m iš vietos registruojant bėgimo greitį ir iš karto atliko neintensyvų aerobinį fizinį krūvį – bėgo 1 km, tada iš karto vėl bėgo 10 m iš vietos registruojant bėgimo greitį, vėl 1 km bėgimas ir trečiasis 10 m bėgimas iš vietos registruojant bėgimo greitį. Iš karto po paskutinio bėgimo buvo matuojama kūno temperatūra, 20 min pasyvus tiriamųjų poilsis ir vėl matuojama kūno temperatūra. Tada tiriamieji atliko paskutinį 10 m bėgimą iš vietos registruojant bėgimo greitį. Antrasis tyrimas: tiriamieji maksimaliomis pastangomis bėgo 10 m iš vietos atstumą 3 kartus iš eilės, tarp bėgimų pasyviai ilsėjosi 5 min. Iš karto po paskutinio bėgimo buvo matuojama kūno temperatūra. Pirmasis sportuojančių asmenų tyrimas parodė, kad taikant neintensyvų aerobinį fizinį krūvį kūno temperatūra padidėja 2,23 % (p < 0,05), taip pat 5,55 % (p < 0,05) padidėja ir 10 m bėgimų iš vietos greitis. Taikant 20 min pasyvų poilsį kūno temperatūra ir bėgimo greitis sumažėja iki pradinės reikšmės. Analogiški rezultatai gauti ir testuojant aktyviai nesportuojančius asmenis: pirmuoju atveju jų kūno temperatūra pakito 1,37 % (p < 0,05), bėgimo greitis padidėjo 4,99 % (p < 0,05), o taikant pasyvų poilsį rezultatai sumažėjo. Antrojo tyrimo metu, kai buvo netaikomas neintensyvus aerobinis fizinis krūvis, abiejų grupių tiriamųjų tiek kūno temperatūra, tiek ir bėgimo greičiai statistiškai patikimai nepakito. Vadinasi: 1) aerobinis fizinis krūvis padidino sportuojančių ir aktyviai nesportuojančių asmenų kūno temperatūrą ir bėgimo greitį; 2) taikant 20 min pasyvų poilsį po fizinio krūvio kūno temperatūra ir bėgimo greitis sumažėjo iki pradinės reikšmės; 3) netaikant aerobinio fizinio krūvio abiejų grupių tiriamųjų bėgimo greitis nedidėjo ir kūno temperatūra išliko nepakitusi.Direct heating of body limbs can have a strong effect on muscle force and strength during isokinetic exercises (Ball et. al., 1999). B. Drust et al. (2005)substantiate, that increased muscle temperature improve dynamic load quality. The aim of the study is to determine the effect of moderate-intensity aerobic physical load on the body temperature and running results in athletes and physically inactive persons. Research organisation. There were two groups in this research: athletes and physically inactive. Athletes group included 19-22 years old males (height 182,7 ± 5,1 cm; weight 72 ± 6,2 kg; n = 6). Physically inactive persons group included healthy males aged 20-23 (height 181,7 ± 6,2 cm; weight 71,7 ± 8,6 kg, n = 15). The test lasted for two days in a 17–18°C temperature environment. On the first research day, before testing, the body temperature was measured placing a mercury thermometer in the armpit for 5 minutes (Dollberg et. al., 2003). Before performing the test, the subjects did stretching exercises without warm up. The start line was curved 70 cm before the line, indicating the beginning of 10 m distance. The take-off foot was placed before the start line, while the trail leg was behind it (1-2 feet). The subjects started to run independently, i.e. without the starter’s command. The subjects ran the distance at maximum efforts as fast as possible with run time recorded (Mamkus et. al., 2004). After one such run race immediately 1 km run followed (the distance had to be covered in 5 min.), and again 10 m run from a standing static position. The described activities were repeated 3 times. The body temperature was measured and one additional 10 m run from a standing static position was performed immediately after the last run and then after 20 min. On the second research day, the beginning phase of the test was the same as on the first day, however, this time the subjects ran 10 m from a standing static position 3 times in a sequence with 5 min rest between the trials. The body temperature was measured immediately after the last run. Both groups performed the same research protocol. [...

The Effect of Heating and Cooling on Time Course of Voluntary and Electrically Induced Muscle Force Variation

The aim of this study was to investigate the effect of heating and cooling on time course of voluntary and electrically induced muscle force variation. Material and Methods. Ten volunteers performed 50 maximal voluntary and electrically induced contractions of the knee extensors at an angle of 120 degrees under the control conditions and after passive lower body heating and cooling in the control, heating, and cooling experiments. Peak torque, torque variation, and half-relaxation time were assessed during the exercise. Results. Passive lower body heating increased muscle and core temperatures, while cooling lowered muscle temperature, but did not affect core temperature. We observed significantly lower muscle fatigue during voluntary contraction compared with electrically induced contractions. Body heating (opposite to cooling) increased involuntarily induced muscle force, but caused greater electrically induced muscle fatigue. In the middle of the exercise, the coefficient of correlation for electrically induced muscle torque decreased significantly as compared with the beginning of the exercise, while during maximal voluntary contractions, this relation for torque remained significant until the end of the exercise. Conclusion. It was shown that time course of voluntary contraction was more stable than in electrically induced contractions

The dynamics of the performance aspects of the best heptathlon athletes of Lithuania and the world

Darbo tikslas – išanalizuoti pasaulio elito septynkovininkių rezultatų kaitą. Uždaviniai: 1. Išanalizuoti geriausių pasaulio septynkovininkių rezultatų kaitą amžiaus aspektu. 2. Išanalizuoti geriausių pasaulio septynkovininkių atskirų septynkovės rungčių rezultatų kaitą. Tyrimo rezultatų analizei duomenys apie pasaulio lengvosios atletikos čempionatų septynkovės rungties finalo dalyves buvo panaudoti iš oficialių dokumentų – „12th IIAF World Championships in Athletics Statistic Handbook, Berlin 2009“ ir internetinio puslapio – www.iaaf.com. Nustatyta: 1. Geriausio asmeninio septynkovės rezultato pasiekimo amžius yra 25,55 ± 3,02 m. Geriausių pasaulio septynkovininkių vidutinis ūgis yra 1,78 ± 0,06 m, svoris – 66,73 ± 5,82 kg. 2. Pasaulio lengvosios atletikos čempionatuose geriausios (8‑tukas) septynkovininkės daugiausia taškų surenka sprinto rungtyse – 31,37 %, panašus indėlis į galutinį rezultatą ir šuolių rungčių – 31,22 %, metimams tenka 25,95 %. Dažniausiai septynkovės čempionės atskirų rungčių nugalėtojomis yra tapusios šuolio į aukštį ir šuolio į tolį sektoriuose – po 5 kartus. Nuo analizuojamojo laikotarpio pradžios labiausiai pagerėjo ieties metimo rungties rezultatas (p < 0,05).Research aim was to analyze the alternation of results of the best world heptathlon athletes. Tasks: 1. To analyze the changes of best heptathlon athlete’s results by year. 2. To analyze best heptathlon athlete’s results changes by separate heptathlon events. Research methods and organization. 1. Analysis ofdocuments and literature; 2. Mathematical statistics (mean, standard deviation, statistical significance of mean differences according to Student criterion); 3. Comparative analysis. After the analysis of the best 8 heptathlon athletes’ percentage share in separate events on final competitions result, we can see that athletes mostly score points in sprint events - 31.37 %, similar contribution on final result is in jump events - 31.22 %, and in throwing - 25.95 %. We have also established that athletes, on average, mostly score in 100 m hurdles event (1068,70 ± 30,37 points) and in high jump event (1033,24 ± 50,18 points). As we use to think it reveals the dominance of speed strength and explosive strength in motor abilities while performing heptathlon event. According to Sandler (2005) and Roberts (1997), in heptathlon event all basic physical characteristics are dominant, such as speed, speed strength, speed endurance, explosive strength, strength speed and endurance; absolute strength does not appear in those events. Conclusions: 1. Highest personal best is reached in heptathlon when athletes age is 25.55 ± 3.02 years. Best heptathlon athletes height is 1,78 ± 0,06 m and weight is 66,73 ± 5,82 kg. 2. The best 8 heptathlon athletes in World championships mostly scores points in sprint events - 31.37 %, similarly in jump events - 31.22 % and in throwing – 25.95 %. Commonly the heptathlon champions win in high jump and long jump events (5 times in each). The biggest improvement of the result was in javelin throwing event from the beginning of analyzed period (p < 0.05)

Pre-Exercise Rehydration Attenuates Central Fatigability during 2-Min Maximum Voluntary Contraction in Hyperthermia

Background and objectives: Hyperthermia with dehydration alters several brain structure volumes, mainly by changing plasma osmolality, thus strongly affecting neural functions (cognitive and motor). Here, we aimed to examine whether the prevention of significant dehydration caused by passively induced whole-body hyperthermia attenuates peripheral and/or central fatigability during a sustained 2-min isometric maximal voluntary contraction (MVC). Materials and Methods: Ten healthy and physically active adult men (21 &plusmn; 1 years of age) performed an isometric MVC of the knee extensors for 2 min (2-min MVC) under control (CON) conditions, after passive lower-body heating that induced severe whole-body hyperthermia (HT, Tre &gt; 39 &deg;C) with dehydration (HT-D) and after HT with rehydration (HT-RH). Results: In the HT-D trial, the subjects lost 0.94 &plusmn; 0.15 kg (1.33% &plusmn; 0.13%) of their body weight; in the HT-RH trial, their body weight increased by 0.1 &plusmn; 0.42 kg (0.1% &plusmn; 0.58%). After lower-body heating, the HT-RH trial (vs. HT-D trial) was accompanied by a significantly lower physiological stress index (6.77 &plusmn; 0.98 vs. 7.40 &plusmn; 1.46, respectively), heart rate (47.8 &plusmn; 9.8 vs. 60.8 &plusmn; 13.2 b min&minus;1, respectively), and systolic blood pressure (&minus;12.52 &plusmn; 5.1 vs. +2.3 &plusmn; 6.4, respectively). During 2-min MVC, hyperthermia (HT-D; HT-RH) resulted in greater central fatigability compared with the CON trial. The voluntary activation of exercising muscles was less depressed in the HT-RH trial compared with the HT-D trial. Over the exercise period, electrically (involuntary) induced torque decreased less in the HT-D trial than in the CON and HT-RH trials. Conclusions: Our results suggest that pre-exercise rehydration might have the immediate positive effect of reducing physiological thermal strain, thus attenuating central fatigability even when exercise is performed during severe (Tre &gt; 39 &deg;C) HT, induced by passive warming of the lower body

Impact of hypotermia and dehydration on the skeletal muscle fatique of men performing isometric exercises of maximum intensity

The aim of the study was to establish the impact of hyperthermia and dehydration and to evaluate the impact of rehydration on the functions of skeletal muscles performing 2 min maximum intensity isometric load under the conditions of hyperthermia. The research participants were male adults not actively engaged in sports (n = 10), aged 22.4 ± 3.4 years, with body mass of 75.1 ± 8.0 kg, and height — 177.6 ± 7.2 cm. Three studies were carried out — one control study and the other two — experimental. During the fi rst experiment the bodies of the research participants experienced hyperthermia and dehydration (research participants kept their legs up to the pelvis in the bath with hot water (44 ± 1oC) for 45 minutes). During the other experiment, using the same methods of increasing hyperthermia, the organisms experienced peroral rehydration with the1000 ml solution of 37oC NaCl 0.9%. The load of maximum voluntary strength (MVS) lasted for 120 seconds, every 15 seconds the muscle was stimulated by electrical impulses — the duration of the stimulation was 250 ms, the frequency was 100 Hz, and the voltage was 85—105 V. We registered the moment of MVS (N*m) and the degree of voluntary activation of muscles VA% = (MVS + electrical impulse) / MVS × 100. When the load was applied the research participants were motivated verbally, and they were provided with the visual feedback of changes in strength signals. After hyperthermia and dehydration was applied, the rectal body temperature averagely increased from 37.33 ± 0.36 to 39.13 ± 0.25oC (p < 0.00), applying rehydration under the conditions of hyperthermia it was from 37.28 ± 0.36 to 39.22 ± 0.4oC (p < 0.001). During the hyperthermia experiment the research participants lost 0.93 ± 0.32 kg on average, and that was 1.17 ± 0.4% of their body mass (Io dehydration).[...]

Impact of hypotermia and dehydration on the skeletal muscle fatique of men performing isometric exercises of maximum intensity

The aim of the study was to establish the impact of hyperthermia and dehydration and to evaluate the impact of rehydration on the functions of skeletal muscles performing 2 min maximum intensity isometric load under the conditions of hyperthermia. The research participants were male adults not actively engaged in sports (n = 10), aged 22.4 ± 3.4 years, with body mass of 75.1 ± 8.0 kg, and height — 177.6 ± 7.2 cm. Three studies were carried out — one control study and the other two — experimental. During the fi rst experiment the bodies of the research participants experienced hyperthermia and dehydration (research participants kept their legs up to the pelvis in the bath with hot water (44 ± 1oC) for 45 minutes). During the other experiment, using the same methods of increasing hyperthermia, the organisms experienced peroral rehydration with the1000 ml solution of 37oC NaCl 0.9%. The load of maximum voluntary strength (MVS) lasted for 120 seconds, every 15 seconds the muscle was stimulated by electrical impulses — the duration of the stimulation was 250 ms, the frequency was 100 Hz, and the voltage was 85—105 V. We registered the moment of MVS (N*m) and the degree of voluntary activation of muscles VA% = (MVS + electrical impulse) / MVS × 100. When the load was applied the research participants were motivated verbally, and they were provided with the visual feedback of changes in strength signals. After hyperthermia and dehydration was applied, the rectal body temperature averagely increased from 37.33 ± 0.36 to 39.13 ± 0.25oC (p < 0.00), applying rehydration under the conditions of hyperthermia it was from 37.28 ± 0.36 to 39.22 ± 0.4oC (p < 0.001). During the hyperthermia experiment the research participants lost 0.93 ± 0.32 kg on average, and that was 1.17 ± 0.4% of their body mass (Io dehydration).[...]

Are motor and cognitive control, impulsivity and risk-taking behaviour as well as moral decision making determined by the activity of prefrontal cortex during Stroop test?

Background. The main aim of our research was to determine if there was a relationship between prefrontal cortex activity during Stroop test (dependent variables) and variables of “Go/NoGo”, Balloon Analogue Risk Task, impulsivity score, different tests of cognitive functions, moral decisions tests (altruistic or egoistic), Fitts-like motor control task, five character traits, emotional intelligence, mood, sleepiness and perceived stress, total physical activity of subjects (independent variables). Methods.In total, 20 undergraduate students (mean age were 21.3, SD=1) met the criteria and agreed to participate in this study. Results. Our research has shown that different brain functional outcomes, that is speed-accuracy motor control, inhibition response control and cognitive performance, risky-taking behaviour and impulsivity control, management of emotion, personality consciousness and physical activity have a common correlation with the increase in prefrontal cortex activity (measured by fNIRS) during Stroop test. Conclusion. Our studies have clearly shown that different brain functional outcomes, that is speed-accuracy motor control, inhibition response control and cognitive performance, risky-taking behaviour and impulsivity control, management of emotion, personality consciousness and physical activity have a common correlation with the increase in prefrontal cortex activity (measured by fNIRS) during Stroop test. Considerable number of studies are needed to understand what is the functional essence of these relationships, but currently there is an increase of research establishing correlations between motor behaviour and cognition control