Ballistography in functional diagnostics of muscle activity in young athletes

BACKGROUND: There is a need to identify new promising methods for the functional assessment of the muscular system in young athletes, the implementation of which may improve monitoring of the training process. AIM: This work aimed to study the parameters of the vertical component of the ground reaction force in young athletes at different levels of physical load. METHODS: The amplitude-frequency characteristics of ballistograms, specifically the parameters of the vertical component of the ground reaction force, were analyzed in 16 male football players aged 8–10 years. Inclusion criteria were children systematically engaged in sports (football) 3 times per week for 1 year or longer. Exclusion criteria were children engaged in sports for less than 1 year and those not adhering to a regular training regimen. Using two stabilometric platforms, oscillations of the vertical component PZ of the ground reaction force, total and those of the contralateral lower extremities, were recorded alternately for 1 s in tests performed in the child’s calm standing position and under load, namely in the standing heel-rise position. Peak amplitudes of PZ oscillations: MLF, MMF, and MHF, and their corresponding frequencies were measured in the low-frequency FLF (1–3 Hz), medium-frequency FMF (3–7 Hz), and high-frequency FHF (7–12 Hz) ranges. The control group consisted of the same number of boys of similar age with ordinary physical activity. RESULTS: In both groups of children, the mean spectral frequency of the vertical component of the ground reaction force, regardless of load level, was 4.0 Hz in the athlete group and 5.0 Hz in the non-athlete group (p = 0.001). Ballistography made it possible to assess muscle activity in the athlete group that differed remarkably from that of their non-athlete peers. Analysis of the parameters of the vertical component of the ground reaction force in the athletes indicates increased skeletal muscle strength and the absence of muscle imbalance and also demonstrates signs of favorable adaptive changes in motor units. Preservation of muscular stability in young athletes undergoing regular, high-intensity training reflects both the high adaptability of the child’s body and the effectiveness of a properly organized training process. CONCLUSION: Considering the need to take into account the functional immaturity of the movement control system, it is advisable to provide systematic instrumental monitoring of their muscular state in the training process of young athletes. To improve the effectiveness of children’s training, the amplitude-frequency characteristics of their ballistograms should be considered, which may help avoid the development of muscle imbalance due to fatigue and, consequently, prevent injuries.