scholarly journals Effects of submaximal cycling at different exercise intensities on maximal isometric force output of the non-exercised elbow flexor muscles

2018 ◽  
Vol 105 (2) ◽  
pp. 177-187
Author(s):  
R Matsuura ◽  
K Hirakoba ◽  
K Takahashi
Keyword(s):  
Isometric Force ◽  
Lactate Concentration ◽  
Elbow Flexor ◽  
Emg Activity ◽  
Force Output ◽  
Cardiorespiratory Responses ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
The Right ◽  
Maximal Isometric Force

The purpose of this study was to examine the effects of submaximal cycling at different exercise intensities on maximal isometric force output of the non-exercised elbow flexor muscles after the cycling. A total of 8 healthy young men performed multiple maximal voluntary contractions by the right elbow flexion before, immediately after, 5 min after, and 10 min after a 6-min submaximal cycling at ventilatory threshold (LI), 70% (MI), and 80% (HI) with both arms relaxed in the air. Force and surface electromyogram (EMG) of the right biceps brachii muscle during the multiple MVCs, blood lactate concentration ([La]), cardiorespiratory responses, and sensations of fatigue for legs (SEF-L) were measured before, immediately after, 5 min after, and 10 min after the submaximal cycling with the three different exercise intensities. Immediately after the submaximal cycling, [La], cardiorespiratory responses, and SEF-L were enhanced in proportion to an increase in exercise intensity of the cycling. Changes in force and EMG activity during the multiple MVCs were not significantly different across the three conditions. The findings imply that group III/IV muscle afferent feedback after the submaximal cycling does not determine the magnitude of MVC force loss of the non-exercised upper limb muscles.

Task Differences With the Same Load Torque Alter the Endurance Time of Submaximal Fatiguing Contractions in Humans

2002 ◽  
Vol 88 (6) ◽  
pp. 3087-3096 ◽  
Author(s):  
Sandra K. Hunter ◽  
Daphne L. Ryan ◽  
Justus D. Ortega ◽  
Roger M. Enoka
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Elbow Flexor ◽  
Emg Activity ◽  
Load Torque ◽  
Endurance Time ◽  
Position Task ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
Fatiguing Contractions

Endurance time, muscle activation, and mean arterial pressure were measured during two types of submaximal fatiguing contractions that required each subject to exert the same net muscle torque in the two tasks. Sixteen men and women performed isometric contractions at 15% of the maximum voluntary contraction (MVC) force with the elbow flexor muscles, either by maintaining a constant force while pushing against a force transducer (force task) or by supporting an equivalent inertial load while maintaining a constant elbow angle (position task). The endurance time for the force task (1402 ± 728 s) was twice as long as that for the position task (702 ± 582 s, P < 0.05), despite a similar reduction in the load torque at exhaustion for each contraction. The rate of increase in average electromyographic activity (EMG, % peak MVC value) for the elbow flexor muscles was similar for the two tasks. However, the average EMG was greater at exhaustion for the force task (22.4 ± 1.2%) compared with the position task (14.9 ± 1.0%, P < 0.05). In contrast, the rates of increase in the mean arterial pressure, the rating of perceived exertion, anterior deltoid EMG, and fluctuations in motor output (force or acceleration) were greater for the position task compared with the force task ( P < 0.05). Furthermore, the rate of bursts in EMG activity, which corresponded to the transient recruitment of motor units, was greater for the brachialis muscle during the position task. These results indicate that the briefer endurance time for the position task was associated with greater levels of excitatory and inhibitory input to the motor neurons compared with the force task.

Elbow Flexor Inhibition as a Function of Muscle Length

2002 ◽  
Vol 18 (1) ◽  
pp. 46-56 ◽  
Author(s):  
Luciana Brondino ◽  
Esther Suter ◽  
Hae-Dong Lee ◽  
Walter Herzog
Keyword(s):  
Isometric Force ◽  
Knee Extensor ◽  
Elbow Flexor ◽  
Peak Force ◽  
Knee Extensors ◽  
Emg Activity ◽  
Elbow Flexors ◽  
Muscle Inhibition ◽  
Voluntary Contractions ◽  
Maximal Isometric Force

Muscle inhibition (MI) in human knee extensors increases with increasing maximal voluntary force as a function of knee angle. It was speculated that this angle-dependent MI was modulated by force-dependent feedback, likely Golgi tendon organ pathways. Such angle-dependent MI is of clinical and theoretical importance. The purpose of this study was to determine MI in human elbow flexors for maximal voluntary contractions. Muscle inhibition, elbow flexor force, and electromyographic (EMG) activity were measured in 31 volunteers at elbow angles between 30º and 120º. MI and elbow flexor EMG were the same at all elbow angles. Maximal isometric forces were greatest at the 70º angle, and never fell below 70% of the peak force at any of the tested angles. From these results it is concluded that force-dependent modulation of MI did not occur in the elbow flexors, possibly because maximal isometric force remained relatively close (within 30%) to the peak force. In contrast, force-dependent modulation of MI occurred in the knee extensors at the most extended angles, when the average knee extensor force had dropped to 50% or less of the maximal knee extensor force. It is likely that human maximal voluntary contractions are not associated with a given activation. Rather, activation appears to be modulated by force-dependent feedback at force levels below 70% of the absolute peak force, which manifests itself in a change of MI that parallels the level of maximal isometric force in voluntary contractions.

scholarly journals Fatigability of the elbow flexor muscles for a sustained submaximal contraction is similar in men and women matched for strength

2004 ◽  
Vol 96 (1) ◽  
pp. 195-202 ◽  
Author(s):  
Sandra K. Hunter ◽  
Ashley Critchlow ◽  
In-Sik Shin ◽  
Roger M. Enoka
Keyword(s):  
Perceived Exertion ◽  
Maximum Voluntary Contraction ◽  
Elbow Flexor ◽  
Rating Of Perceived Exertion ◽  
Emg Activity ◽  
Men And Women ◽  
Task Failure ◽  
Rate Of Increase ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles

The purpose of this study was to compare the time to task failure for a submaximal fatiguing contraction sustained with the elbow flexor muscles by men and women who were matched for strength ( n = 20, 18-35 yr). The maximal torque exerted at the wrist was similar for the men and women [64.5 ± 8.7 (SD) vs. 64.5 ± 8.3 N·m; P > 0.05], which meant that the average torque exerted during the fatiguing contraction [20% of maximum voluntary contraction (MVC)] was similar for the two sexes. The time to task failure was similar for these strength-matched men and women (819 ± 306 vs. 864 ± 391 s; P > 0.05). The mean arterial pressure was similar at the beginning of the contraction for men (97 ± 12 mmHg) and women (96 ± 15 mmHg; P > 0.05) and at task failure (134 ± 18 vs. 126 ± 26 mmHg; P > 0.05, respectively). Furthermore, the increases in heart rate, torque fluctuations, and rating of perceived exertion during the fatiguing contraction were similar for the two sexes. However, the electromyogram (EMG) activity differed for the men and women: the rate of increase in the average of the rectified EMG (% peak MVC) for all the elbow flexor muscles was less for the women compared with the men ( P < 0.05). Furthermore, the bursts of EMG activity for the elbow flexor muscles increased toward exhaustion for all subjects but at a greater rate for the women compared with the men ( P < 0.05). The results indicate that strength-matched men and women experienced similar levels of muscle fatigue and cardiovascular adjustments during a sustained low-force isometric contraction, despite differences in the EMG activity for the two groups of subjects.

scholarly journals The reliability of Berger’s table in estimating 1-RM and 10-RM of the elbow flexor muscles in normal young adults

2001 ◽  
Vol 57 (2) ◽  
pp. 11-15
Author(s):  
A. O. Akinpelu ◽  
J. O. Iyaniwura ◽  
B. O. Ajagbe
Keyword(s):  
Young Adults ◽  
Muscle Group ◽  
Elbow Flexor ◽  
Regression Equations ◽  
Elbow Flexors ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
The Right ◽  
Isotonic Strength

Isotonic strength training remains one of the methods of strengthening muscles, as it requires inexpensive materials. The method requires the determination of maximal isotonic strength or one repetition maximum [1-RM] and/or sub-maximal isotonic strength (2-RM - 10-RM) of a muscle group in order to know the appropriate resistance to subject the muscle group to, and to monitor strength gains by the muscle group. Berger’s table contains percentages for predicting 1-RM - 10-RM, and it is intended to improve the efficiency of determining isotonic muscle strength. The aim of this study was to investigate the reliability of Berger’s table in predicting 1-RM and 10-RM of the right elbow flexor muscles.1-RM and 10-RM were estimated using Berger’s table in 100 young adults following the determination of the number of repetitions that could be carried out against randomly selected weights. Weight adjustments were made to obtain the actual 1-RM and 10-RM. Data were subjected to regression analysis. A significant linear relationship exists between the estimated and actual values of 1-RM and 10-RM. Results also showed that Berger’s table explains 93% of 1-RM and 98% of 10-RM. It was concluded that Berger’s table is reliable in determining 1-RM and 10-RM of the elbow flexors in young healthy adults. Regression equations that may improve the accuracy of estimation were derived.

Activation among the elbow flexor muscles differs when maintaining arm position during a fatiguing contraction

2003 ◽  
Vol 94 (6) ◽  
pp. 2439-2447 ◽  
Author(s):  
Sandra K. Hunter ◽  
Romuald Lepers ◽  
Carol J. MacGillis ◽  
Roger M. Enoka
Keyword(s):  
Biceps Brachii ◽  
Maximum Voluntary Contraction ◽  
Elbow Flexor ◽  
The Other ◽  
Emg Activity ◽  
Inhibitory Input ◽  
Endurance Time ◽  
Rate Of Increase ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles

Twenty-four men ( n = 11) and women ( n = 13) supported an inertial load equivalent to 20% of the maximum voluntary contraction force with the elbow flexor muscles for as long as possible while maintaining a constant elbow angle at 90°. Endurance time did not differ on the three occasions that the task was performed (320 ± 149 s; P > 0.05), and there was no difference between women (360 ± 168 s) and men (273 ± 108 s; P = 0.11). The rate of increase in average electromyogram (EMG) for the elbow flexor muscles was similar across sessions ( P > 0.05). However, average EMG during the fatiguing task increased for the long head of biceps brachii, brachioradialis, and brachialis ( P < 0.05) but not for the short head of biceps brachii. Furthermore, the average EMG for the brachialis was greater at the start and end of the contraction compared with the other elbow flexor muscles. The rate of bursts in EMG activity increased during the fatiguing contraction and was greater in brachialis (1.0 ± 0.2 bursts/min) compared with the other elbow flexor muscles (0.5 ± 0.1 bursts/min). The changes in the standard deviation of acceleration, mean arterial pressure, and heart rate during the fatiguing contractions were similar across sessions. These findings indicate that the EMG activity, which reflects the net excitatory and inhibitory input received by the motoneurons in the spinal cord, was not adaptable over repeat sessions for the maintain-position task. Furthermore, these results contrast those from a previous study (Hunter SK and Enoka RM. J Appl Physiol 94: 108–118, 2003) when the goal of the isometric contraction was to maintain a constant force. These results, from a series of studies on the elbow flexor muscles, indicate that the type of load supported during the fatiguing contraction influences the extent to which endurance time can change with repeat performances of the task.

scholarly journals Downhill running impairs peripheral but not central neuromuscular indices in elbow flexor muscles

2021 ◽  
Author(s):  
Xin Ye ◽  
Robert J. Benton ◽  
William M. Miller ◽  
Sunggun Jeon ◽  
Jun Seob Song
Keyword(s):  
Elbow Flexor ◽  
Downhill Running ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles

Older Adults Use a Unique Strategy to Lift Inertial Loads With the Elbow Flexor Muscles

2000 ◽  
Vol 83 (4) ◽  
pp. 2030-2039 ◽  
Author(s):  
Andrew E. Graves ◽  
Kurt W. Kornatz ◽  
Roger M. Enoka
Keyword(s):  
Young Adults ◽  
Elbow Joint ◽  
Muscle Activation ◽  
Angular Displacement ◽  
Elbow Flexor ◽  
Lengthening Contractions ◽  
Old Adults ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
Target Force

The purpose of this study was to determine the effect of age on the ability to exert steady forces and to perform steady flexion movements with the muscles that cross the elbow joint. An isometric task required subjects to exert a steady force to match a target force that was displayed on a monitor. An anisometric task required subjects to raise and lower inertial loads so that the angular displacement around the elbow joint matched a template displayed on a monitor. Steadiness was measured as the coefficient of variation of force and as the normalized standard deviation of wrist acceleration. For the isometric task, steadiness as a function of target force decreased similarly for old adults and young adults. For the anisometric task, steadiness increased as a function of the inertial load and there were significant differences caused by age. Old adults were less steady than young adults during both shortening and lengthening contractions with the lightest loads. Furthermore, old adults were least steady when performing lengthening contractions. These behaviors appear to be associated with the patterns of muscle activation. These results suggest that different neural strategies are used to control isometric and anisometric contractions performed with the elbow flexor muscles and that these strategies do not change in parallel with advancing age.

scholarly journals Determining Consistency of Elbow Joint Threshold Angle in Elbow Flexor Muscles With Spastic Hypertonia

1996 ◽  
Vol 76 (6) ◽  
pp. 586-600 ◽  
Author(s):  
Steven L Wolf ◽  
Richard L Segal ◽  
Pamela A Catlin ◽  
Julie Tschorn ◽  
Tina Raleigh ◽  
...  
Keyword(s):  
Elbow Joint ◽  
Elbow Flexor ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles
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