Research Article
Model of Force Calculation of Fast and Slow Motor Units of Knee Extensor Muscles in Isometric Mode
Issue:
Volume 14, Issue 1, March 2026
Pages:
1-7
Received:
6 October 2025
Accepted:
29 October 2025
Published:
7 January 2026
DOI:
10.11648/j.ajss.20261401.11
Downloads:
Views:
Abstract: Knee extensors are mixed muscles containing both fast (FMU) and slow motor units (SMU). It has been hypothesized that, at high angular velocities (150-360 deg/s), FMU contributes primarily to knee joint moment development, while at low angular velocities (30-120 deg/s), both FMU and SMU contribute to force generation. It was hypothesized that the maximum isometric moment in m. quadriceps, registered on the isokinetic dynamometer “BIODEX System 4Pro”at speeds of 30-150 deg/s, represents the sum of the moments from SMU and FMU, while in the range of 150-360 deg/s, it is primarily generated by FMU. The maximum isometric moment created by the FMU was calculated using a linear equation, as the force-velocity relationship becomes linear at high velocities. During knee extension at a constant angular velocity, the maximum number of RMUs, according to the model, is activated up to an angular velocity of 240 deg/s: (knee amplitude motion 90 deg) / (time developing maximum force 0.37s) = 240 deg/s. The maximum number of MMUs is recruited 1.09 s after the onset of knee extension, which corresponds to an angular velocity of 90 deg/based on the results of isokinetic dynamometry and a mathematical model, FMU and SMU forces were calculated for highly skilled athletes of different sports. For athletes of various specializations, the SMU force does not exceed 24 N/kg, while the FMU force ranges from 52-83 N/kg. The main result of this study demonstrates an acceptable level of agreement between the model and experimental calculations of the SMU and FMU contributions to knee extension force. Based on the obtained model characteristics, individual "boundaries" of SMU and FMU involvement can be determined.
Abstract: Knee extensors are mixed muscles containing both fast (FMU) and slow motor units (SMU). It has been hypothesized that, at high angular velocities (150-360 deg/s), FMU contributes primarily to knee joint moment development, while at low angular velocities (30-120 deg/s), both FMU and SMU contribute to force generation. It was hypothesized that the m...
Show More
Research Article
Realization of Speed-strength Manifestations at Improvement of Metabolism of Energy of Muscle Contraction
Issue:
Volume 14, Issue 1, March 2026
Pages:
8-12
Received:
18 October 2025
Accepted:
31 October 2025
Published:
7 January 2026
DOI:
10.11648/j.ajss.20261401.12
Downloads:
Views:
Abstract: The aim of the study is to: improve the speed-strength qualities of freestyle wrestlers and judokas; develop their endurance in anaerobic exercises; and increase lactate utilization during speed-strength exercises and during the recovery period during the improvement stage of athletic skill. Methods and organization of the study. Analysis and synthesis of scientific and methodological literary sources. Pedagogical observations, an experimental study, and physiological and biochemical (lactic acid (lactate) concentration levels in capillary blood) methods were used. A comparison of the effectiveness of speed-strength exercises, including wrestling techniques, and blood lactate levels during the recovery period. Freestyle wrestlers and judokas in the experimental group performed aerobic exercises during the recovery process with movement coordination similar to the exercise being trained. Wrestlers in the control group used passive rest to recover from anaerobic exercise. Study results and conclusions. As a result of performing control anaerobic exercises at the end of the experimental training session, subjects who used active rest for recovery demonstrated a significant positive improvement in their results. Moreover, blood lactate levels remained virtually unchanged during the first minutes, but starting from the third minute, lactate utilization significantly (p<0.05) improved compared to baseline. At the end of the experiment, wrestlers who used passive rest demonstrated significantly (p<0.05) lower performance in control exercises than wrestlers who used active rest, while their blood lactate levels increased significantly (p<0.05) compared to baseline.
Abstract: The aim of the study is to: improve the speed-strength qualities of freestyle wrestlers and judokas; develop their endurance in anaerobic exercises; and increase lactate utilization during speed-strength exercises and during the recovery period during the improvement stage of athletic skill. Methods and organization of the study. Analysis and synth...
Show More
,
Elena Tomilovskaya
