The aim of the study was to evaluate the effect of plyometric training (PT) on central and peripheral (muscle) fatigue in prepubertal girls and boys. The boys (n = 13, age 10.3 ± 0.3 years) and girls (n = 13, age, 10.2 ± 0.3 years) performed continuous 2-min maximal voluntary contractions (MVCs) before and after 16 high-intensity PT sessions. PT comprised two training sessions per week of 30 jumps in each session with 20 s between jumps. The greatest effect of PT was on excitation–contraction coupling, (twitch force increased by 323% in boys and 21% in girls) and height of a counter–movement jump (increased by 37% in boys and 38% in girls). In contrast, the quadriceps voluntary activation index, central activation ratio, and MVC did not change significantly after PT. The thickness of the quadriceps muscle increased by 9% in boys and 14% in girls after PT. In conclusion, boys and girls demonstrated similar changes in indicators of central fatigue (50–60% decrease) and peripheral fatigue (45–55% decrease) after MVC before and after PT.
Albertas Skurvydas and Marius Brazaitis
Vytautas Streckis, Albertas Skurvydas, and Aivaras Ratkevicius
The aim of this study was to compare low-frequency fatigue (LFF) after 100 drop jumps in boys (age = 12.7 ± 0.7 years, mean ± SD) and men (age = 25.6 ± 1.7 years). The force-generating-capacity test (FGCT) of knee extensor muscles was performed before the exercise, as well as 3 and 20 min after the exercise. Before exercise, men were stronger than boys, but twitch time characteristics did not differ between the groups. The 20:50 Hz torque ratio was similar in boys and men as well (0.71 ± 0.08 and 0.73 ± 0.08, respectively). After exercise, at 20 min of recovery, the 20:50 Hz ratio was depressed to 48.9 ± 11.6% of initial in men and to 74.5 ± 10.0% of initial in boys (p < .05). There was no significant difference between boys and men in ground-reaction forces of drop jumps when the values were normalized to body mass. It is argued that intrinsic differences in the muscle-tendon complex are responsible for less severe LFF in boys compared with men.
Laura Zlibinaite, Albertas Skurvydas, Sandra Kilikeviciene, and Rima Solianik
Background: The effect of globally recommended levels of physical activity on cognition and motor behavior is not completely understood. Therefore, the main aim of this study was to assess the effect of 300 minutes per week of moderate-intensity aerobic exercise on cognitive and motor performance among overweight and obese working-age women. Methods: Overweight and obese participants aged 38–56 years were randomized to either a control or an experimental group performing aerobic exercise at 50% to 60% of the peak oxygen consumption for a 2-month period. Changes in aerobic fitness, cardiac autonomic function, brain-derived neurotropic factor levels, and cognitive and motor performance were assessed. Results: Although aerobic exercise reduced body weight (P < .05) and improved peak oxygen consumption (P < .05), the brain-derived neurotropic factor levels and cognitive and motor performance remained unchanged. Heart rate and blood pressure decreased (P < .05), whereas heart rate variability indices were not affected. No significant correlations between changes in heart rate variability indices and cognition were observed. Conclusions: Two months of moderate-intensity aerobic exercise decreased sympathetic activity and improved cardiovascular fitness but had no impact on cognition or motor control among these middle-aged, overweight, and obese women.
Laura Žlibinaitė, Rima Solianik, Daiva Vizbaraitė, Dalia Mickevičienė, and Albertas Skurvydas
Background: The benefits of weight loss programs on mood, cognitive, and motor behavior are largely limited to those of calorie restriction or exercise alone. Our aim was to investigate the effect of combined calorie restriction and aerobic exercise intervention on mood, brain activity, and cognitive and motor behavior in overweight and obese women. Methods: Participants aged 36–56 years were randomized to either a control or an experimental group (aerobic exercise + 12.5% energy intake reduction) for a 6-month period. Changes in brain-derived neurotrophic factor levels, mood, prefrontal cortex activity, cognitive and motor performance were assessed. Results: Confusion and depression increased in the control group (P < .05), whereas tension decreased in the experimental group (P < .05). Brain-derived neurotrophic factor level and learning of a speed–accuracy task remained unchanged. Although prefrontal cortex activity and executive functions were not affected, the reaction time of visual scanning and associative learning were improved in the experimental group (P < .05). An improvement in reaction time during the speed–accuracy task was observed (P < .05). Conclusion: Combined calorie restriction and aerobic exercise intervention improved the psychosocial state, had little impact on cognition, and no effect on brain activity and learning of the speed–accuracy task.
Dalia Mickeviciene, Renata Rutkauskaite, Dovile Valanciene, Diana Karanauskiene, Marius Brazaitis, and Albertas Skurvydas
The aim of the study was to establish whether there were differences in speed–accuracy movement learning strategies between children, young adults, and older adults. A total of 30 boys, 30 young adult men, and 30 older men were seated in a special chair at a table with a Dynamic Parameter Analyzer 1. Participants had to perform a speed–accuracy task with the right-dominant hand. It may be assumed that the motor variables of children are more prone to change during the fast learning process than those of young adults and older adults and that the development of internal models is more changeable in children than in young adults and the older adults during the fast adaptation-based learning process.