Twelve- to Thirteen-Year-Old Boys Are More Resistant to Low-Frequency Fatigue than Young Men

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.

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Increasing the resting time between drop jumps lessens delayed-onset muscle soreness and limits the extent of prolonged low-frequency force depression in human knee extensor muscles

European Journal of Applied Physiology ◽

10.1007/s00421-021-04834-x ◽

2021 ◽

Author(s):

Sigitas Kamandulis ◽

Mantas Mickevicius ◽

Audrius Snieckus ◽

Vytautas Streckis ◽

Diego Montiel-Rojas ◽

...

Keyword(s):

Muscle Soreness ◽

Low Frequency ◽

Knee Extensor ◽

Delayed Onset Muscle Soreness ◽

Human Knee ◽

Delayed Onset ◽

Force Depression ◽

Extensor Muscles ◽

Drop Jumps ◽

Knee Extensor Muscles

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Effects of chronic low-frequency electrical stimulation of human knee extensor muscles exposed to static passive stretching

Human Physiology ◽

10.1134/s0362119706010117 ◽

2006 ◽

Vol 32 (1) ◽

pp. 74-80 ◽

Cited By ~ 1

Author(s):

B. S. Shenkman ◽

E. V. Lyubaeva ◽

D. V. Popov ◽

A. I. Netreba ◽

O. S. Tarasova ◽

...

Keyword(s):

Electrical Stimulation ◽

Low Frequency ◽

Knee Extensor ◽

Human Knee ◽

Passive Stretching ◽

Extensor Muscles ◽

Knee Extensor Muscles ◽

Stimulation Of

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Does the Early and Late Rate of Torque Development, Change in Relation to the Quadriceps Angle?

Journal of Education and Training Studies ◽

10.11114/jets.v7i3s.4003 ◽

2019 ◽

Vol 7 (3S) ◽

pp. 1

Author(s):

Ajlan Saç

Keyword(s):

Lower Extremity ◽

Knee Injuries ◽

Knee Extensor ◽

Myoelectrical Activity ◽

Rate Of Torque Development ◽

Q Angle ◽

Extensor Muscles ◽

Significant Difference ◽

Torque Development ◽

Knee Extensor Muscles

The rate of torque development (RTD), which determines the force that can be developed in the early phase of muscle contraction (0-200 ms), is very important in terms of tracking explosive strength improvement and preventing knee injuries. The purpose of this study was to investigate the relationship of quadriceps angle which affects the structural alignment of the lower extremity with early (0-100 ms) and late (100-200 ms) rate of torque development of the knee extensor muscles and myoelectrical activity. The study was carried out with 38 well-trained male basketball players (mean age: 22.3±2.5 years). The participants were divided into two groups with normal (<11°) and abnormal (>10°) values. RTD was measured in concentric/concentric mode at 60, 120 and 180°/s angular velocities in an isokinetic dynamometer. Surface electromyography (sEMG) was used to determine the myoelectrical activity. When RTD0-100 and RTD100-200 were examined, statistically significant difference was observed at 60 and 120°/s (p<0.05). However, no difference was observed at 180°/s. In addition, sEMG data did not have a statistically significant difference between groups. Negative correlation was found between all RTD at 60, 10 and 180°/s with Q angle (180°/s RTD0-100 r= -0.34, 180°/s RTD100-200 r= -0.35, 120°/s RTD0-100 r= -0.40, 120°/s RTD100-200 r= -0.48, 60°/s RTD0-100 r= -0.55, 60°/s RTD100-200 r= -0.59; p<0.05). There was a negative correlation between the structural differences of the lower extremity and the early and late rate of torque development of the knee extensor muscles. Considering the structural variables, it is thought that it is important to improve the rate of torque development with appropriate resistance training in athletes with variables such as abnormal Q angle, and thus knee injuries can be prevented through athletic development.

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PO-166 Neuromuscular Fatigue after maximal Concentric and Eccentric Contractions of Knee Extensor

Exercise Biochemistry Review ◽

10.14428/ebr.v1i4.11933 ◽

2018 ◽

Vol 1 (4) ◽

Author(s):

Shenpeng Xu ◽

Ying Wang ◽

Wan Chen

Keyword(s):

Electrical Stimulation ◽

Knee Flexion ◽

Low Frequency ◽

Knee Extensor ◽

Knee Extension ◽

Neuromuscular Fatigue ◽

Peripheral Fatigue ◽

Concentric Exercise ◽

Significant Difference ◽

Low Frequency Fatigue

Objective The aim of this study was to investigate after different maximal contractions concentric and eccentric would cause different neuromuscular fatigue of knee extensor. Methods Ten healthy young men(21≤age≤24) who were not adapted by electrical stimulation were the subjects.The subjects were asked to arrive at the laboratory in three weeks at the same time of every week to avoid the effects of biological rhythms.Each subject performed three group maximal contractions on the ISOMED2000 isokinetic muscle tester according to the requirements.The subjects performed the same neuromuscular function test before and after exercise.The centripetal motion scheme:3*30,M1(knee flexion)-CON,M2(knee extension)-CON.angular velocity is 60 °,interval 30s in each group.Centrifugal motion scheme:3*30,M1(knee flexion)-ECC,M2(knee extension)-ECC.angular velocity is 60 °,interval 30s in each group. Results The decrease rate of peak torque after concentric exercise was 55.93±13.20%, which was significantly higher than that after centrifugal exercise (20.06 ±11.06%, P < 0.01)The total work of the concentric movement was 8737.20±1543.43J, which was significantly smaller than that of the centrifugal exercise group (14312.20±2978.31J, P < 0. 01).The decline rate of MVC in concentric exercise was 24.89 ±10.54 and that in centrifugal exercise was 19.32±9.90,there was no significant difference between the two groups. Double Twitch induced a very significant decrease in PT-SSR RFD-SSN RHD-SS (P<0.01).There was no significant difference in VA decline rate.PAP decreased from 142.82±14.55% to 125.23±11.36 after concentric exercise, and after eccentric exercise PAP decreased from 141.1215.72% to 126.02 ±10.45. Conclusions The neuromuscular fatigue caused by two kinds of exercise. Peripheral fatigue accounted for 39.19% after concentric exercise and 23.59% after centrifugal exercise,but there was little difference in the degree of central fatigue.All of them showed low frequency fatigue, and the low frequency fatigue after centrifugal exercise was more obvious. Key World:Neuromuscular fatigue; Electrical stimulation; High-frequency fatigue; Low-frequency fatigue; PAP.

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