Age Characteristics of Fatigue During Cyclic Work of Maximum Power

Abstract

The purpose of the article is a study the age-related features of changes in the functional state of the neuromuscular apparatus during cyclic work before failure in laboratory conditions. Methods:14 adult ski racers (25-28 years old) candidates for masters of sports and 12 teenagers (14-15 years old) I and II sports categories took part in the study. As the maximum physical load (before failure), an imitation of alternating two-step walking in place was used.For each subject, the walking pace was 75% of the maximum.Ski racers performed imitation under an electronic metronome. The length of the step remained unchanged throughout the study; the duration of the simulation reached 30-40 minutes.The following physiological indicators were used to assess the state of the neuromuscular apparatus: reflex excitability of spinal motoneurons (according to the amplitude of the maximum H-response); latent period of H- and M-responses; the speed of propagation of excitation along the sensory and motor fibers of the tibial nerve in the area of the popliteal fossa and the medial condyle (bone) of the tibia using the "Micro-Neuro-Soft" electroneuromyography.Results. It was established that the relative share of motoneurons participating in the reflex response is the same in resting adults and young skiers. The duration of physical exercise in teenagers reached approximately the same values ​​as adult athletes and is 30-40 minutes. However, the dynamics of the studied functional indicators had their own specific features: in young ski racers, the amplitude of the H-response when refusing to continue working decreased by only 24.0% compared to the initial level. Conclusion. Reflex excitability of spinal motoneurons after performing cyclic work of maximum power in adult athletes is more pronounced than in adolescent athletes, which indicates faster fatigue after testing, but high physical performance during testing.