scholarly journals Using Customized Rate-Coding and Recruitment Strategies to Maintain Forces During Repetitive Activation of Human Muscles

2008 ◽  
Vol 88 (3) ◽  
pp. 363-375 ◽  
Author(s):  
Li-Wei Chou ◽  
Trisha M Kesar ◽  
Stuart A Binder-Macleod
Keyword(s):  
Muscle Activation ◽  
Force Production ◽  
Stimulation Frequency ◽  
Peak Force ◽  
Muscle Performance ◽  
Force Level ◽  
Stimulation Intensity ◽  
History Of ◽  
Rate Coding ◽  
The Right

Background and Purpose During functional electrical stimulation (FES), clinicians typically increase stimulation intensity to offset fatigue and maintain functional levels of force production. However, recent studies have suggested that increasing the stimulation frequency is an effective strategy for overcoming fatigue during FES. The purpose of this study was to compare the effectiveness of 5 stimulation strategies on maintaining forces during repetitive isometric muscle activation. Subjects and Methods The right quadriceps femoris muscles of 12 subjects with no history of lower-extremity orthopedic, neurological, or vascular problems were tested. The 5 stimulation strategies were: progressively increasing the frequency, progressively increasing the intensity, and 3 combination protocols that first increased the intensity and then increased the frequency. The only difference among the 3 combination protocols was the starting frequency used in each protocol (20, 30, or 40 Hz). For all protocols, the stimulation frequency or intensity was increased progressively every time the peak force declined more than 10% from a targeted force level. The specific step increases in frequency or intensity were customized for each subject. A contraction was defined as successful when its peak force exceeded 90% of the targeted force level. Results The results showed that progressively increasing only the frequency produced 59% more successful contractions than progressively increasing only the intensity. In addition, the combination stimulation protocol that began with 30-Hz trains produced the most successful contractions (mean=1,205 contractions; 35%–74% more than the other 4 protocols tested). Discussion and Conclusions The results suggest that increasing the stimulation intensity and then the frequency is the best strategy to maintain muscle performance and could help clinicians design optimal stimulation protocols to use for each patient during FES.

The Effect of Neuromuscular Electrical Stimulation of the Infraspinatus on Shoulder External Rotation Force Production after Rotator Cuff Repair Surgery

2008 ◽  
Vol 36 (12) ◽  
pp. 2317-2321 ◽  
Author(s):  
Michael M. Reinold ◽  
Leonard C. Macrina ◽  
Kevin E. Wilk ◽  
Jeffrey R. Dugas ◽  
E. Lyle Cain ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Rotator Cuff ◽  
Rotator Cuff Repair ◽  
External Rotation ◽  
Neuromuscular Electrical Stimulation ◽  
Force Production ◽  
Peak Force ◽  
Stimulation Intensity ◽  
Shoulder External Rotation ◽  
Cuff Repair

Background Muscle weakness, particularly of shoulder external rotation, is common after rotator cuff repair surgery. Neuromuscular electrical stimulation has been shown to be an effective adjunct in the enhancement of muscle recruitment. Hypothesis Shoulder external rotation peak force can be enhanced by neuromuscular electrical stimulation after rotator cuff repair surgery. Study Design Controlled laboratory study. Methods Thirty-nine patients (20 men, 19 women) who had undergone rotator cuff repair surgery were tested a mean of 10.5 days after surgery. Testing consisted of placing patients supine with the shoulder in 45° of abduction, neutral rotation, and 15° of horizontal adduction. Neuromuscular electrical stimulation was applied to the infraspinatus muscle belly and inferior to the spine of the scapula. Placement was confirmed by palpating the muscle during a resisted isometric contraction of the external rotators. Patients performed 3 isometric shoulder external rotation contractions with and without neuromuscular electrical stimulation, each with a 5-second hold against a handheld dynamometer. Neuromuscular electrical stimulation was applied at maximal intensity within comfort at 50 pulses per second, symmetrical waveform, and a 1-second ramp time. The 3 trials under each condition were recorded, and an average was taken. The order of testing was randomized for each patient tested. A paired samples t test was used to determine significant differences between conditions ( P < .05). Each group was also divided based on age, rotator cuff tear size, number of days postoperative, and neuromuscular electrical stimulation intensity. Analysis of variance Models were used to determine the influence of these variables on external rotation force production ( P < .05). Results Peak force production was significantly greater ( P < .001) when tested with neuromuscular electrical stimulation (3.75 kg) as opposed to without neuromuscular electrical stimulation (3.08 kg) for all groups tested. There was no significant difference based on the size of the tear, age of the patient, number of days after surgery, or level of neuromuscular electrical stimulation intensity. Conclusion Peak shoulder external rotation force was significantly increased by 22% when tested with neuromuscular electrical stimulation after rotator cuff repair surgery. Neuromuscular electrical stimulation significantly increased force production regardless of the age of the patient, size of the tear, intensity of the current, or the number of days postoperative. Clinical Relevance Neuromuscular electrical stimulation may be used concomitantly with exercises to enhance the amount of force production and potentially minimize the inhibition of the rotator cuff after repair surgery.

scholarly journals The Effects of Body Tempering on Force Production, Flexibility and Muscle Soreness in Collegiate Football Athletes

2022 ◽  
Vol 7 (1) ◽  
pp. 9
Author(s):  
Christopher B. Taber ◽  
Roy J. Colter ◽  
Jair J. Davis ◽  
Patrick A. Seweje ◽  
Dustin P. Wilson ◽  
...  
Keyword(s):  
Muscle Soreness ◽  
Force Production ◽  
The Body ◽  
Peak Force ◽  
Muscle Performance ◽  
Dynamic Force ◽  
Jump Height ◽  
Negative Effect ◽  
Production Flexibility ◽  
Baseline Testing

There has been limited research to explore the use of body tempering and when the use of this modality would be most appropriate. This study aimed to determine if a body tempering intervention would be appropriate pre-exercise by examining its effects on perceived soreness, range of motion (ROM), and force production compared to an intervention of traditional stretching. The subjects for this study were ten Division 1 (D1) football linemen from Sacred Heart University (Age: 19.9 ± 1.5 years, body mass: 130.9 ± 12.0 kg, height: 188.4 ± 5.1 cm, training age: 8.0 ± 3.5 years). Subjects participated in three sessions with the first session being baseline testing. The second and third sessions involved the participants being randomized to receive either the body tempering or stretching intervention for the second session and then receiving the other intervention the final week. Soreness using a visual analog scale (VAS), ROM, counter movement jump (CMJ) peak force and jump height, static jump (SJ) peak force and jump height, and isometric mid-thigh pull max force production were assessed. The results of the study concluded that body tempering does not have a negative effect on muscle performance but did practically reduce perceived muscle soreness. Since body tempering is effective at reducing soreness in athletes, it can be recommended for athletes as part of their pre-exercise warmup without negatively effecting isometric or dynamic force production.

scholarly journals Effect Of Handedness On Functional Organization Of Bimanual Isometric Handgrip

2015 ◽  
Vol 8 (1) ◽  
pp. 13-18
Author(s):  
Nikolai V. Kolev ◽  
Ljudmila I. Halacheva
Keyword(s):  
Functional Organization ◽  
Force Production ◽  
Peak Force ◽  
Dominant Hand ◽  
Isometric Handgrip ◽  
Bilateral Deficit ◽  
Time To Peak ◽  
Left Handed ◽  
Force Time ◽  
The Right

SummaryThe aim of this study was to examine force production during maximal isometric handgrip in unilateral (UL) and bilateral (BL) tasks in right- and left-handed subjects. Ten right-handed (RH) and 8 left-handed (LH) young men were studied. The subjects were instructed, after a command, to perform a shot-like handgrip, raising maximal force as fast as possible. Three series were performed as follows: 1) UL - right handgrip; 2) UL - left handgrip; 3) BL handgrip. We measured peak force, time to peak of force and rate of force. The BL/UL ratios for the right (R) and left (L) hand and L/R ratios for the UL and BL tasks were calculated. The L/R ratios for peak force and force rate in RH group ranged across all tasks and conditions from 0.71 to 0.75. They were significantly lower than 1 (p<0.01). These ratios did not differ significantly from 1 for LH subjects (0.98–1.02), indicating the handedness in RH group only. The BL/UL ratios for peak force were 0.89 and 0.89 in RH, suggesting symmetrical bilateral strength deficit. The magnitude of the bilateral deficit in LH group was larger for the dominant (L) hand compared to non dominant (R) hand – 0.93 and 0.97 (p<0.05) respectively, suggesting an asymmetry of bilateral deficit in LH. These ratios for time of force and rate of force indicated bilateral deficit (BD) in the dominant hand of RH group only.

Effects of Fatigue on Kinetic and Kinematic Variables During a 60-Second Repeated Jumps Test

2010 ◽  
Vol 5 (2) ◽  
pp. 218-229 ◽  
Author(s):  
Jeni R. McNeal ◽  
William A. Sands ◽  
Michael H. Stone
Keyword(s):  
Muscle Activation ◽  
Female Athletes ◽  
Vastus Lateralis ◽  
Force Production ◽  
Biceps Femoris ◽  
Peak Force ◽  
Ground Contact ◽  
And Gender ◽  
Anterior Tibialis ◽  
Initial Jump

Purpose:The aim of this study was to investigate the effects of a maximal repeated-jumps task on force production, muscle activation and kinematics, and to determine if changes in performance were dependent on gender.Methods:Eleven male and nine female athletes performed continuous countermovement jumps for 60 s on a force platform while muscle activation was assessed using surface electromyography. Performances were videotaped and digitized (60 Hz). Data were averaged across three jumps in 10-s intervals from the initial jump to the final 10 s of the test.Results:No interaction between time and gender was evident for any variable; therefore, all results represent data collapsed across gender. Preactivation magnitude decreased across time periods for anterior tibialis (AT, P < .001), gastrocnemius (GAS, P < .001) and biceps femoris (BF, P = .03), but not for vastus lateralis (VL, P = .16). Muscle activation during ground contact did not change across time for BF; however, VL, G, and AT showed significant reductions (all P < .001). Peak force was reduced at 40 s compared with the initial jumps, and continued to be reduced at 50 and 60 s (all P < .05). The time from peak force to takeoff was greater at 50 and 60 s compared with the initial jumps (P < .05). Both knee fexion and ankle dorsifexion were reduced across time (both P < .001), whereas no change in relative hip angle was evident (P = .10). Absolute angle of the trunk increased with time (P < .001), whereas the absolute angle of the shank decreased (P < .001).Conclusions:In response to the fatiguing task, subjects reduced muscle activation and force production and altered jumping technique; however, these changes were not dependent on gender.

Reaction time and response dynamics

1987 ◽  
Vol 39 (2) ◽  
pp. 337-360 ◽  
Author(s):  
Les G. Carlton ◽  
Mary J. Carlton ◽  
K. M. Newell
Keyword(s):  
Reaction Time ◽  
Exponential Function ◽  
Choice Reaction Time ◽  
Force Production ◽  
Peak Force ◽  
Force Level ◽  
Response Dynamics ◽  
Response Parameter ◽  
The Relationship

The experiments reported were designed to examine the relationship between reaction time and the response dynamics of a finger-press task. Experiments 1 and 2 manipulated force duration and peak force level in both simple and choice reaction-time paradigms. Experiment 3 constrained both force duration and peak force, leading to independent changes in the rate of force production. The findings from all three experiments suggest that the rate of force production, rather than force duration, is the key response parameter determining reaction time. Reaction time decreased as an exponential function of rate of force production independent of force duration and peak force.

scholarly journals History-Dependence of Muscle Excitation and Oxygenation During Isometric Knee Extension Force Production

2020 ◽  
Vol 29 (4) ◽  
pp. 385-393
Author(s):  
Junkyung Song ◽  
Kitae Kim ◽  
Sungjun Lee ◽  
Jiseop Lee ◽  
Jaebum Park
Keyword(s):  
Muscle Activation ◽  
Force Production ◽  
Time History ◽  
Knee Extension ◽  
Terminal Phase ◽  
History Dependence ◽  
Isometric Knee Extension ◽  
Extension Force ◽  
History Of ◽  
Four Levels

PURPOSE:This study examined the issue of history-dependence on muscle excitation and oxygenation by using surface electromyography (EMG) and near-infrared spectroscopy (NIRS).METHODS: Eight male participants performed isometric knee extension force production tasks that started at four levels of initial force production (30, 40, 60, 70% of maximal voluntary contraction, MVC) and commonly converged to the production of 50% of MVC by increasing or decreasing knee extension forces. We quantified the integrated electromyogram (iEMG), total hemoglobin (tHb), and the desaturation rate of muscle tissue (TSI<sub>SLOPE</sub>) of the vastus lateralis and compared the differences in the quantified variables between the experimental conditions.RESULTS: For the four levels of initial forces production, all the variables showed significant linear relationships with outcome forces. However, the magnitudes of the variables were varied depending on the contraction history at the terminal phase where the identical level of force production (50% of MVC) was required. At the terminal phase, the iEMG was affected by the time history of both mode (e.g., increment or decrement) and magnitude (e.g., 10% or 20% change of MVC), while the tHb and TSI<sub>SLOPE</sub> showed significant differences between the time history of mode only.CONCLUSIONS:The main result of the current study demonstrates the history-dependence of the changes in physiological demands in muscle activation. In particular, the indices of muscle excitation and oxygenation at the same level of force were varied depending on the time history of contraction, which implies the indices of muscle excitation and oxygenation may not be invariant component to specify the levels of outcome forces.

scholarly journals Immediate Effects of Acupuncture on Explosive Force Production and Stiffness in Male Knee Joint

2021 ◽  
Vol 18 (18) ◽  
pp. 9518
Author(s):  
Jun Wang ◽  
I-Lin Wang ◽  
Rui Hu ◽  
Shun Yao ◽  
Yu Su ◽  
...  
Keyword(s):  
Knee Joint ◽  
Muscle Activation ◽  
Average Power ◽  
Joint Stiffness ◽  
Force Production ◽  
Sham Acupuncture ◽  
Significant Interaction Effect ◽  
Average Maximum ◽  
Explosive Force ◽  
The Right

Acupuncture can improve explosive force production and affect joint stiffness by affecting muscle activation levels. This study aims to explore the effects of true acupuncture (TA) compared with sham acupuncture (SA) on the explosive force production and stiffness of the knee joint in healthy male subjects. Twenty subjects were randomly divided into the TA group (n = 10) and SA group (n = 10) to complete isokinetic movement of the right knee joint at a speed of 240°/s before and after acupuncture. Futu (ST32), Liangqiu (ST34), Zusanli (ST36), Xuehai (SP10), and Chengshan (BL57) were selected for acupuncture. The intervention of SA is that needles with a blunt tip were pushed against the skin, giving an illusion of insertion. The results showed that acupuncture and the intervention time had a significant interaction effect on knee joint explosive force and joint stiffness (p < 0.05). The average maximum (max) torque, average work, average power, average peak power and total work of the TA group increased significantly after acupuncture (p < 0.05), while the SA group did not (p > 0.05). Therefore, true acupuncture can immediately improve the explosive force and joint stiffness of the male knee joint by inducing post-activation potentiation (PAP) and/or De-Qi.

Z-line degradation and phagocytosis of sarcomeric fragments in myonecrosis

1983 ◽  
Vol 41 ◽  
pp. 790-791
Author(s):  
Melinda L. Estes ◽  
Samuel M. Chou
Keyword(s):  
Vastus Lateralis ◽  
Inflammatory Myopathy ◽  
Muscle Disease ◽  
White Female ◽  
Inflammatory Cell Infiltrate ◽  
Limb Weakness ◽  
Muscle Diseases ◽  
History Of ◽  
The Right ◽  
Mononuclear Inflammatory Cell

Many muscle diseases show common pathological features although their etiology is different. In primary muscle diseases a characteristic finding is myofiber necrosis. The mechanism of myonecrosis is unknown. Polymyositis is a primary muscle disease characterized by acute and subacute degeneration as well as regeneration of muscle fibers coupled with an inflammatory infiltrate. We present a case of polymyositis with unusual ultrastructural features indicative of the basic pathogenetic process involved in myonecrosis.The patient is a 63-year-old white female with a one history of proximal limb weakness, weight loss and fatigue. Examination revealed mild proximal weakness and diminished deep tendon reflexes. Her creatine kinase was 1800 mU/ml (normal < 140 mU/ml) and electromyography was consistent with an inflammatory myopathy which was verified by light microscopy on biopsy muscle. Ultrastructural study of necrotizing myofiber, from the right vastus lateralis, showed: (1) degradation of the Z-lines with preservation of the adjacent Abands including M-lines and H-bands, (Fig. 1), (2) fracture of the sarcomeres at the I-bands with disappearance of the Z-lines, (Fig. 2), (3) fragmented sarcomeres without I-bands, engulfed by invading phagocytes, (Fig. 3, a & b ), and (4) mononuclear inflammatory cell infiltrate in the endomysium.

Popliteal artery thrombosis secondary to a tibial osteochondroma

VASA ◽  
2011 ◽  
Vol 40 (3) ◽  
pp. 251-255 ◽  
Author(s):  
Gruber-Szydlo ◽  
Poreba ◽  
Belowska-Bien ◽  
Derkacz ◽  
Badowski ◽  
...  
Keyword(s):  
Case Report ◽  
Magnetic Resonance Angiography ◽  
Popliteal Artery ◽  
Doppler Ultrasonography ◽  
Histopathological Examination ◽  
Previous History ◽  
Plain Radiography ◽  
Artery Thrombosis ◽  
History Of ◽  
The Right

Popliteal artery thrombosis may present as a complication of an osteochondroma located in the vicinity of the knee joint. This is a case report of a 26-year-old man with symptoms of the right lower extremity ischaemia without a previous history of vascular disease or trauma. Plain radiography, magnetic resonance angiography and Doppler ultrasonography documented the presence of an osteochondrous structure of the proximal tibial metaphysis, which displaced and compressed the popliteal artery, causing its occlusion due to intraluminal thrombosis..The patient was operated and histopathological examination confirmed the diagnosis of osteochondroma.

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