scholarly journals Contraction frequency modulates muscle fatigue and the rate of myoglobin desaturation during incremental contractions in humans

2008 ◽  
Vol 33 (5) ◽  
pp. 915-921 ◽  
Author(s):  
Danielle M. Wigmore ◽  
Douglas E. Befroy ◽  
Ian R. Lanza ◽  
Jane A. Kent-Braun
Keyword(s):  
Muscle Fatigue ◽  
Muscle Force ◽  
Force Production ◽  
Metabolic Cost ◽  
Resonance Spectroscopy ◽  
Isometric Contractions ◽  
Metabolic Demand ◽  
Contraction Frequency ◽  
Duty Cycles ◽  
Force Time

The metabolic cost of force production, and therefore the demand for oxygen, increases with intensity and frequency of contraction. This study investigated the interaction between fatigue and oxygenation, as reflected by deoxymyoglobin (dMb), during slow and rapid rhythmic isometric contractions having the same duty cycles and relative force–time integrals (FTIs). We used 1H magnetic resonance spectroscopy and measures of dorsiflexor muscle force to compare dMb and fatigue (fall of maximal voluntary force, MVC) in 11 healthy adults (29 ± 7 y) during 16 min of slow (4 s contraction, 6 s relaxation) and rapid (1.2 s, 1.8 s) incremental (10%–80% MVC) contractions. We tested the hypotheses that (i) the rate of Mb desaturation would be faster in rapid than in slow contractions and (ii) fatigue, Mb desaturation, and the fall in FTI would be greater, and PO2 (oxygen tension) lower, at the end of rapid contractions than at the end of slow contractions. Although dMb increased more quickly during rapid contractions (p = 0.05), it reached a plateau at a similar level in both protocols (~42% max, p = 0.49), likely due to an inability to further increase force production and thus metabolic demand. Despite the similar dMb at the end of both protocols, fatigue was greater in rapid (56.6% ± 2.7% baseline) than in slow (69.5% ± 4.0%, p = 0.01) contractions. These results indicate that human skeletal muscle fatigue during incremental isometric contractions is in part a function of contraction frequency, possibly due to metabolic inhibition of the contractile process.

Effect of intracellular pH on force development depends on temperature in intact skeletal muscle from mouse

1996 ◽  
Vol 271 (3) ◽  
pp. C878-C886 ◽  
Author(s):  
R. W. Wiseman ◽  
T. W. Beck ◽  
P. B. Chase
Keyword(s):  
Muscle Fatigue ◽  
Intracellular Ph ◽  
Force Production ◽  
Resonance Spectroscopy ◽  
Dependent Inhibition ◽  
Effects Of Ph ◽  
Different Temperatures ◽  
Lower Temperature ◽  
Glycerinated Fibers

The cellular mechanism of muscle fatigue is still in debate. Opposite conclusions regarding the role of intracellular pH (pHi) in fatigue have been drawn from skinned fiber vs. isolated perfused muscle studies. Because these experiments are typically performed at different temperatures, we tested the hypothesis that temperature alters the effects of pH on force. Tetanic force of isolated mouse extensor digitorum longus was measured at temperatures between 13 and 25 degrees C in either normocapnia (5% CO2) or hypercapnia (25% CO2). Hypercapnia decreased pHi (monitored by 31P nuclear magnetic resonance spectroscopy) by the same amount at both 15 and 25 degrees C. However, inhibition of force by hypercapnia was greater at the lower temperature. A similar pattern of temperature-dependent inhibition of force by pH was observed in glycerinated fibers from rabbit psoas at maximum Ca2+ activation. We conclude that temperature differences are responsible for disparate conclusions on the role of pHi in muscle fatigue. Based on our results, we suggest that changes in pHi may have little or no role in the loss in force production associated with muscular fatigue at physiological temperatures.

scholarly journals The metabolic cost of in vivo constant muscle force production at zero net mechanical work

2019 ◽  
Vol 222 (8) ◽  
pp. jeb199158 ◽  
Author(s):  
Tim J. van der Zee ◽  
Koen K. Lemaire ◽  
Arthur J. van Soest
Keyword(s):  
Muscle Force ◽  
Force Production ◽  
Metabolic Cost ◽  
Mechanical Work ◽  
Muscle Force Production

scholarly journals Effect of xanthine oxidase-generated extracellular superoxide on skeletal muscle force generation

2010 ◽  
Vol 298 (1) ◽  
pp. R2-R8 ◽  
Author(s):  
M. C. Gomez-Cabrera ◽  
G. L. Close ◽  
A. Kayani ◽  
A. McArdle ◽  
J. Viña ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Polyethylene Glycol ◽  
Cytochrome C ◽  
Extracellular Space ◽  
Superoxide Anion ◽  
Skeletal Muscles ◽  
Muscle Force ◽  
Force Production ◽  
Force Generation ◽  
Isometric Contractions

Skeletal muscle contractions increase superoxide anion in skeletal muscle extracellular space. We tested the hypotheses that 1) after an isometric contraction protocol, xanthine oxidase (XO) activity is a source of superoxide anion in the extracellular space of skeletal muscle and 2) the increase in XO-derived extracellular superoxide anion during contractions affects skeletal muscle contractile function. Superoxide anion was monitored in the extracellular space of mouse gastrocnemius muscles by following the reduction of cytochrome c in muscle microdialysates. A 15-min protocol of nondamaging isometric contractions increased the reduction of cytochrome c in microdialysates, indicating an increase in superoxide anion. Mice treated with the XO inhibitor oxypurinol showed a smaller increase in superoxide anions in muscle microdialysates following contractions than in microdialysates from muscles of vehicle-treated mice. Intact extensor digitorum longus (EDL) and soleus muscles from mice were also incubated in vitro with oxypurinol or polyethylene glycol-tagged Cu,Zn-SOD. Oxypurinol decreased the maximum tetanic force produced by EDL and soleus muscles, and polyethylene glycol-tagged Cu,Zn-SOD decreased the maximum force production by the EDL muscles. Neither agent influenced the rate of decline in force production when EDL or soleus muscles were repeatedly electrically stimulated using a 5-min fatiguing protocol (stimulation at 40 Hz for 0.1 s every 5 s). Thus these studies indicate that XO activity contributes to the increased superoxide anion detected within the extracellular space of skeletal muscles during nondamaging contractile activity and that XO-derived superoxide anion or derivatives of this radical have a positive effect on muscle force generation during isometric contractions of mouse skeletal muscles.

scholarly journals Neural control of muscle force: indications from a simulation model

2013 ◽  
Vol 109 (6) ◽  
pp. 1548-1570 ◽  
Author(s):  
Paola Contessa ◽  
Carlo J. De Luca
Keyword(s):  
Motor Unit ◽  
Neural Control ◽  
Muscle Force ◽  
Force Production ◽  
Motor Units ◽  
Isometric Contractions ◽  
Alternative Mechanism ◽  
Firing Behavior ◽  
Firing Rates ◽  
Muscle Force Production

We developed a model to investigate the influence of the muscle force twitch on the simulated firing behavior of motoneurons and muscle force production during voluntary isometric contractions. The input consists of an excitatory signal common to all the motor units in the pool of a muscle, consistent with the “common drive” property. Motor units respond with a hierarchically structured firing behavior wherein at any time and force, firing rates are inversely proportional to recruitment threshold, as described by the “onion skin” property. Time- and force-dependent changes in muscle force production are introduced by varying the motor unit force twitches as a function of time or by varying the number of active motor units. A force feedback adjusts the input excitation, maintaining the simulated force at a target level. The simulations replicate motor unit behavior characteristics similar to those reported in previous empirical studies of sustained contractions: 1) the initial decrease and subsequent increase of firing rates, 2) the derecruitment and recruitment of motor units throughout sustained contractions, and 3) the continual increase in the force fluctuation caused by the progressive recruitment of larger motor units. The model cautions the use of motor unit behavior at recruitment and derecruitment without consideration of changes in the muscle force generation capacity. It describes an alternative mechanism for the reserve capacity of motor units to generate extraordinary force. It supports the hypothesis that the control of motoneurons remains invariant during force-varying and sustained isometric contractions.

Effects of length and stimulation frequency on fatigue of the human tibialis anterior muscle

1994 ◽  
Vol 77 (3) ◽  
pp. 1148-1154 ◽  
Author(s):  
P. Sacco ◽  
D. B. McIntyre ◽  
D. A. Jones
Keyword(s):  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Force Production ◽  
Metabolic Cost ◽  
Normal Subjects ◽  
Fatigue Properties ◽  
High Frequency Stimulation ◽  
Resonance Spectroscopy ◽  
Frequency Stimulation ◽  
Human Tibialis Anterior Muscle

It has been suggested that the reduced fatigability of muscles exercised at short length may result from a decrease in the metabolic cost of contractions in the shortened position. We compared the fatigue properties and metabolic cost of stimulated isometric tetanic contractions in the tibialis anterior of 10 normal subjects at the optimum length (Lo) for force production and when the muscle was shortened (Ls). Six 15-s ischemic contractions at Ls caused force to decline to 53% of the fresh value when tested at Lo, whereas muscles exercised and tested at Lo declined to 40% of fresh force. However, the extent of fatigue was proportionately greater if the muscle was exercised and tested at Ls. The apparent fatigue resistance of short muscles was found to be a consequence of recovery occurring under ischemic conditions while the muscle was changed from Ls to Lo-. 31P-nuclear magnetic resonance spectroscopy showed similar metabolic changes associated with 5-s stimulated contractions at Lo and Ls, indicating that any differences in fatigability at the two lengths were not caused by altered metabolic costs. The similarity between the force profiles of muscles fatigued at Ls and those fatigued by high-frequency stimulation supports the hypothesis that an enhanced activation failure occurs at Ls, possibly resulting from failure of sarcolemmal action potential propagation in the transverse tubules.

scholarly journals Effect of habitual foot-strike pattern on the gastrocnemius medialis muscle-tendon interaction and muscle force production during running

2019 ◽  
Vol 126 (3) ◽  
pp. 708-716 ◽  
Author(s):  
Wannes Swinnen ◽  
Wouter Hoogkamer ◽  
Tijs Delabastita ◽  
Jeroen Aeles ◽  
Friedl De Groote ◽  
...  
Keyword(s):  
Energy Demand ◽  
Muscle Force ◽  
Force Production ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Ground Contact ◽  
Muscle Forces ◽  
Flexor Muscle ◽  
Contraction Velocity ◽  
Foot Strike

The interaction between gastrocnemius medialis (GM) muscle and Achilles tendon, i.e., muscle-tendon unit (MTU) interaction, plays an important role in minimizing the metabolic cost of running. Foot-strike pattern (FSP) has been suggested to alter MTU interaction and subsequently the metabolic cost of running. However, metabolic data from experimental studies on FSP are inconsistent, and a comparison of MTU interaction between FSP is still lacking. We, therefore, investigated the effect of habitual rearfoot and mid-/forefoot striking on MTU interaction, ankle joint work, and plantar flexor muscle force production while running at 10 and 14 km/h. GM muscle fascicles of 9 rearfoot and 10 mid-/forefoot strikers were tracked using dynamic ultrasonography during treadmill running. We collected kinetic and kinematic data and used musculoskeletal models to determine joint angles and calculate MTU lengths. In addition, we used dynamic optimization to assess plantar flexor muscle forces. During ground contact, GM fascicle shortening ( P = 0.02) and average contraction velocity ( P = 0.01) were 40–45% greater in rearfoot strikers than mid-/forefoot strikers. Differences in contraction velocity were especially prominent during early ground contact. Moreover, GM ( P = 0.02) muscle force was greater during early ground contact in mid-/forefoot strikers than rearfoot strikers. Interestingly, we did not find differences in stretch or recoil of the series elastic element between FSP. Our results suggest that, for the GM, the reduced muscle energy cost associated with lower fascicle contraction velocity in mid-/forefoot strikers may be counteracted by greater muscle forces during early ground contact. NEW & NOTEWORTHY Kinetic and kinematic differences between foot-strike patterns during running imply (not previously reported) altered muscle-tendon interaction. Here, we studied muscle-tendon interaction using ultrasonography. We found greater fascicle contraction velocities and lower muscle forces in rearfoot compared with mid-/forefoot strikers. Our results suggest that the higher metabolic energy demand due to greater fascicle contraction velocities might offset the lower metabolic energy demand due to lower muscle forces in rearfoot compared with mid-/forefoot strikers.

Unilateral isometric muscle fatigue decreases force production and activation of contralateral knee extensors but not elbow flexors

2014 ◽  
Vol 39 (12) ◽  
pp. 1338-1344 ◽  
Author(s):  
Israel Halperin ◽  
David Copithorne ◽  
David G. Behm
Keyword(s):  
Muscle Fatigue ◽  
Force Production ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Elbow Flexors ◽  
Post Intervention ◽  
Nonlocal Effects ◽  
And Performance ◽  
Voluntary Contractions ◽  
Isometric Muscle

Nonlocal muscle fatigue occurs when fatiguing 1 muscle alters performance of another rested muscle. The purpose of the study was to investigate if fatiguing 2 separate muscles would affect the same rested muscle, and if fatiguing the same muscle would affect 2 separate muscles. Twenty-one trained males participated in 2 studies (n = 11; n = 10). Subjects performed 2 pre-test maximum voluntary contractions (MVCs) with the nondominant knee extensors. Thereafter they performed two 100-s MVCs with their dominant knee extensors, elbow flexors, or rested. Between and after the sets, a single MVC with the nondominant rested knee extensors was performed. Subsequently, 12 nondominant knee extensors repeated MVCs were completed. Force, quadriceps voluntary activation (VA), and electromyography (EMG) were measured. The same protocol was employed in study 2 except the nondominant elbow-flexors were tested. Study 1: Compared with control conditions, a significant decrease in nondominant knee extensors force, EMG, and VA was found under both fatiguing conditions (P ≤ 0.05; effect size (ES) = 0.91–1.15; 2%–8%). Additionally, decrements in all variables were found from the first post-intervention MVC to the last (P ≤ 0.05; ES = 0.82–2.40; 9%–20%). Study 2: No differences were found between conditions for all variables (P ≥ 0.33; ES ≤ 0.2; ≤3.0%). However, all variables decreased from the first post-intervention MVC to the last (P ≤ 0.05; ES = 0.4–3.0; 7.2%–19.7%). Whereas the rested knee extensors demonstrated nonlocal effects regardless of the muscle being fatigued, the elbow-flexors remained unaffected. This suggests that nonlocal effects are muscle specific, which may hold functional implications for training and performance.

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