ATP synthesis and proton handling in muscle during short periods of exercise and subsequent recovery

2003 ◽  
Vol 94 (6) ◽  
pp. 2391-2397 ◽  
Author(s):  
David Bendahan ◽  
Graham J. Kemp ◽  
Magali Roussel ◽  
Yann Le Fur ◽  
Patrick J. Cozzone
Keyword(s):  
Maximum Voluntary Contraction ◽  
Lactate Production ◽  
Atp Synthesis ◽  
Voluntary Contraction ◽  
Intracellular Water ◽  
Resonance Spectroscopy ◽  
Proton Production ◽  
Finger Flexion ◽  
Flexor Muscles ◽  
Finger Flexor Muscles

We used31P-magnetic resonance spectroscopy to study proton buffering in finger flexor muscles of eight healthy men (25–45 yr), during brief (18-s) voluntary finger flexion exercise (0.67-Hz contraction at 10% maximum voluntary contraction; 50/50 duty cycle) and 180-s recovery. Phosphocreatine (PCr) concentration fell 19 ± 2% during exercise and then recovered with half time = 0.24 ± 0.01 min. Cell pH rose by 0.058 ± 0.003 units during exercise as a result of H+ consumption by PCr splitting, which (assuming no lactate production or H+ efflux) implies a plausible non-Pi buffer capacity of 20 ± 3 mmol · l intracellular water−1 · pH unit−1. There was thus no evidence of significant glycogenolysis to lactate during exercise. Analysis of PCr kinetics as a classic linear response suggests that oxidative ATP synthesis reached 48 ± 2% of ATP demand by the end of exercise; the rest was met by PCr splitting. Postexercise pH recovery was faster than predicted, suggesting “excess proton” production, with a peak value of 0.6 ± 0.2 mmol/l intracellular water at 0.45 min of recovery, which might be due to, e.g., proton influx driven by cellular alkalinization, or a small glycolytic contribution to PCr resynthesis in recovery.

FORCE SUMMATION AND TWITCH POTENTIATION CAPACITY IN HUMAN ANKLE PLANTAR- AND DORSI-FLEXOR MUSCLES

2014 ◽  
Vol 17 (04) ◽  
pp. 1450015
Author(s):  
Yoichi Ohta ◽  
Kengo Yotani
Keyword(s):  
Muscle Function ◽  
Pulse Train ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Twitch Potentiation ◽  
Flexor Muscles ◽  
Human Ankle ◽  
Before And After ◽  
Isometric Torque ◽  
Plantar Flexor Muscles

Purpose: The present study aimed to clarify inter-individual correlation between the magnitudes of force summation and the post-activation potentiation (PAP), in human ankle plantar- and dorsi-flexor muscles. Methods: We analyzed 10 male participants plantar-flexor muscles and the 12 male participants dorsi-flexor muscles using a database from a previous study. Before and after maximum voluntary contraction, we measured the amount of isometric torque evoked by a single, double- and triple-pulse train stimulus. Results: The magnitude of PAP was significantly positively correlated with the magnitude of force summation in both the plantar- and dorsi-flexor muscles. Conclusions: The present study confirmed the correlation between the magnitudes of force summation and PAP in human ankle plantar- and dorsi-flexor muscles. This suggests that muscle characteristics affecting the force summation capacity depend on the PAP, to some degree. These results suggest that the combination of both parameters might enhance the usefulness of evaluating changes in muscle function using intrinsic contractile properties.

Comparative analysis of skeletal muscle oxidative capacity in children and adults: a 31P-MRS study

2008 ◽  
Vol 33 (4) ◽  
pp. 720-727 ◽  
Author(s):  
Sébastien Ratel ◽  
Anne Tonson ◽  
Yann Le Fur ◽  
Patrick Cozzone ◽  
David Bendahan
Keyword(s):  
Intermittent Exercise ◽  
Oxidative Capacity ◽  
Voluntary Contraction ◽  
Resonance Spectroscopy ◽  
Muscle Oxidative Capacity ◽  
Atp Production ◽  
Flexor Muscles ◽  
Forearm Flexor Muscles ◽  
Forearm Flexor

The aim of the present study was to compare the oxidative capacity of the forearm flexor muscles in vivo between children and adults using 31-phosphorus magnetic resonance spectroscopy. Seven boys (11.7 ± 0.6 y) and 10 men (35.6 ± 7.8 year) volunteered to perform a 3 min dynamic finger flexions exercise against a standardized weight (15% of the maximal voluntary contraction). Muscle oxidative capacity was quantified on the basis of phosphocreatine (PCr) post-exercise recovery kinetics analysis. End-of-exercise pH was not significantly different between children and adults (6.6 ± 0.2 vs. 6.5 ± 0.2), indicating that indices of PCr recovery kinetics can be reliably compared. The rate constant of PCr recovery (kPCr) and the maximum rate of aerobic ATP production were about 2-fold higher in young boys than in men (kPCr: 1.7 ± 1.2 vs. 0.7 ± 0.2 min–1; Vmax: 49.7 ± 24.6 vs. 29.4 ± 7.9 mmol·L–1·min–1, p < 0.05). Our results clearly illustrate a greater mitochondrial oxidative capacity in the forearm flexor muscles of young children. This larger ATP regeneration capacity through aerobic mechanisms in children could be one of the factors accounting for their greater resistance to fatigue during high-intensity intermittent exercise.

Increased Oxidative and Delayed Glycogenolytic ATP Synthesis in Exercising Skeletal Muscle of Obese (Insulin-Resistant) Zucker Rats

1996 ◽  
Vol 91 (6) ◽  
pp. 691-702 ◽  
Author(s):  
A. L. Sanderson ◽  
G. J. Kemp ◽  
C. H. Thompson ◽  
G. K. Radda
Keyword(s):  
Skeletal Muscle ◽  
Water Content ◽  
Atp Synthesis ◽  
Intracellular Water ◽  
Zucker Rats ◽  
Resonance Spectroscopy ◽  
Metabolic Efficiency ◽  
Marker Enzyme ◽  
Insulin Resistant ◽  
Kinetics Of

1. To examine metabolic correlates of insulin resistance in skeletal muscle, we used 31P magnetic resonance spectroscopy to study glycogenolytic and oxidative ATP synthesis in leg muscle of lean and obese Zucker rats in vivo during 6 min sciatic nerve stimulation at 2 Hz. 2. The water content of resting muscle was reduced by 21 ± 7% in obese (insulin-resistant) animals compared with lean animals, whereas the lipid content was increased by 140 ± 70%. These results suggest that intracellular water content was reduced by 17% in obese animals. 3. During exercise, although twitch tensions were not significantly different in the two groups, rates of total ATP synthesis (expressed per litre of intracellular water) were 48 ± 20% higher in obese animals, suggesting a 50 ± 8% reduction in intrinsic ‘metabolic efficiency’. Changes in phosphocreatine and ADP concentration were significantly greater in obese animals than in lean animals, whereas changes in intracellular pH did not differ. 4. These results imply that oxidative ATP synthesis during exercise is activated earlier in obese animals than in lean animals. This difference was not fully accounted for by the greater increase in the concentration of the mitochondrial activating signal ADP. Neither the post-exercise recovery kinetics of phosphocreatine nor the muscle content of the mitochondrial marker enzyme citrate synthase was significantly different in the two groups. The increased oxidative ATP synthesis in exercise must therefore be due to altered kinetics of mitochondrial activation by signals other than ADP. 5. Thus, the insulin-resistant muscle of obese animals may compensate for its decreased efficiency (and consequent increased need for ATP) by increased reliance on oxidative ATP synthesis.

Isometric Contraction of Arm Flexor Muscles as a Method of Evaluating Cardiac Vagal Tone in Man

1997 ◽  
Vol 92 (2) ◽  
pp. 175-180 ◽  
Author(s):  
M. Al-Ani ◽  
K. Robins ◽  
A. H. Al-Khalidi ◽  
J. Vaile ◽  
J. Townend ◽  
...  
Keyword(s):  
Heart Rate ◽  
Isometric Contraction ◽  
Maximum Voluntary Contraction ◽  
Young Male ◽  
Vagal Tone ◽  
Voluntary Contraction ◽  
Respiratory Cycle ◽  
Cardiac Vagal Tone ◽  
Flexor Muscles ◽  
Voluntary Contractions

1. We have previously shown that brief voluntary isometric contractions of upper arm flexor muscles performed for one respiratory cycle elicit a significant decrease in the R—R interval. The present study was designed to determine if similar changes are produced by non-voluntary electrically evoked contractions and, if so, to establish the consistency and repeatability of the associated changes in the R—R interval. 2. The heart rate (R—R interval) response to voluntary or non-voluntary brief isometric contraction equivalent to 40% of the maximum voluntary contraction was studied in 10 healthy young male subjects during controlled ventilation at supine rest. 3. The absolute values of R—R intervals occurring in any one of 10 arbitrary phases of a respiratory cycle were measured and plotted by a computer. 4. Both voluntary and non-voluntary contractions elicited similar changes in heart rate and R—R interval, which were greater during expiration than during inspiration. 5. This confirms our previous finding that the magnitude of the R—R interval changes, with brief isometric contraction, is positively related to the degree of cardiac vagal tone. 6. Analysis of the variability between repeated tests initiated in either inspiration or expiration revealed that there was significantly less variability with the electrically induced contraction. 7. It was concluded that electrically induced contractions of 40% maximal voluntary contraction are a viable alternative to voluntary contractions and provide a more controllable means of measuring cardiac vagal withdrawal.

Training partially reverses skeletal muscle metabolic abnormalities during exercise in heart failure

1994 ◽  
Vol 76 (4) ◽  
pp. 1575-1582 ◽  
Author(s):  
J. R. Stratton ◽  
J. F. Dunn ◽  
S. Adamopoulos ◽  
G. J. Kemp ◽  
A. J. Coats ◽  
...  
Keyword(s):  
Heart Failure ◽  
Skeletal Muscle ◽  
Atp Synthesis ◽  
Exercise Duration ◽  
Oxidative Capacity ◽  
Voluntary Contraction ◽  
Resonance Spectroscopy ◽  
Metabolic Abnormalities ◽  
Maximal Rate ◽  
Muscle Training

Using 31P-magnetic resonance spectroscopy during and after exercise, we studied whether forearm metabolic responses to exercise were improved by 1 mo of training in 10 males with heart failure. In the control (untrained) arm, there were no changes in any of the measured variables. In the trained arm, maximal voluntary contraction increased 6% (P = 0.05). During incremental exercise, duration increased 19% (P < 0.05) and submaximal responses improved for pH (6.78 +/- 0.13 pretraining vs. 6.85 +/- 0.17 posttraining; P < 0.01) and PCr/(PCr+Pi) (where PCr is phosphocreatine; 0.48 +/- 0.09 pretraining vs. 0.52 +/- 0.07 posttraining; P < 0.01). The PCr resynthesis rate increased by 48% (P < 0.01), and estimated effective maximal rate of mitochondrial ATP synthesis increased by 37% (P < 0.05). Endurance exercise duration increased by 67% (P < 0.01), and submaximal levels of PCr/(PCr+Pi) (P < 0.05) and pH (P = 0.07) improved. The PCr resynthesis rate (P < 0.01) and the effective maximal rate of mitochondrial ATP synthesis (P < 0.05) also improved. These findings document that impaired oxidative capacity of skeletal muscle can be improved by local muscle training in heart failure, which is compatible with the hypothesis that a part of the abnormality present in heart failure may be due to inactivity.

Activation of glycolysis in human muscle in vivo

1997 ◽  
Vol 273 (1) ◽  
pp. C306-C315 ◽  
Author(s):  
K. E. Conley ◽  
M. L. Blei ◽  
T. L. Richards ◽  
M. J. Kushmerick ◽  
S. A. Jubrias
Keyword(s):  
Muscle Activation ◽  
Feedback Regulation ◽  
Atp Synthesis ◽  
Resonance Spectroscopy ◽  
Control Mechanisms ◽  
Atp Production ◽  
Proton Production ◽  
Sugar Phosphates ◽  
Glycolytic Rate

We tested the cytoplasmic control mechanisms for glycolytic ATP synthesis in human wrist flexor muscles. The forearm was made ischemic and activated by maximal twitch stimulation of the median and ulnar nerves in 10 subjects. Kinetic changes in phosphocreatine, Pi, ADP, ATP, sugar phosphates, and pH were measured by 31P magnetic resonance spectroscopy at 7.1-s intervals. Proton production was determined from pH and tissue buffer capacity during stimulation. Glycolysis was activated between 30 and 50 stimulations, and the rate did not significantly change through the stimulation period. The independence of glycolytic rate on [Pi], [ADP], or [AMP] indicates that feedback regulation by these metabolites could not account for this activation of glycolysis. However, glycolytic H+ and ATP production increased sixfold from 0.5 to 3 Hz, indicating that glycolytic rate reflected muscle activation frequency. This dependence of glycolytic rate on muscle stimulation frequency and independence on metabolite levels is consistent with control of glycolysis by Ca2+.

scholarly journals Core Stability and Electromyographic Activity of the Trunk Musculature in Different Woman’s Sports

2020 ◽  
Vol 12 (23) ◽  
pp. 9880
Author(s):  
Paula Esteban-García ◽  
Jacobo Á. Rubio-Arias ◽  
Javier Abián-Vicen ◽  
Jorge Sánchez-Infante ◽  
José Fernando Jiménez-Díaz
Keyword(s):  
Body Composition ◽  
Maximum Voluntary Contraction ◽  
Sport Performance ◽  
Voluntary Contraction ◽  
Trunk Muscle ◽  
Core Stability ◽  
Electromyographic Activity ◽  
Flexor Muscles ◽  
Volleyball Players ◽  
Rhythmic Gymnasts

Volleyball players and gymnasts need strength training to achieve their optimum sport performance. The aims of this study were to describe body composition, strength, performance, and characteristics of trunk muscle activation in volleyball players and gymnasts, and to analyze the differences between the sports. The sample consisted of 40 female athletes: rhythmic gymnasts (n = 24; age 13.95 ± 2.77 years) and volleyball players (n = 16; age 19.81 ± 5.55 years). Body composition, maximum voluntary contraction (MVC) of isometric tests in an isokinetic dynamometer, McGill core endurance test, and surface electromyography (EMGrms) of the trunk muscle during the McGill test and isometric tests were recorded. Rhythmic gymnasts presented lower body composition values than volleyball players (p < 0.05). The volleyball players presented higher isometric strength than rhythmic gymnasts in terms of MVC in trunk flexion (p < 0.05, d = 1.3) and trunk extension (p < 0.001, d = 1.3). EMGrms from the rhythmic gymnasts were greater for trunk flexor muscles (p < 0.01, d = 0.7) and trunk extensor muscles (p < 0.001, d = 1.3) during McGill endurance tests compared to the volleyball players. In the isometric test, EMGrms from the rhythmic gymnasts were greater for trunk flexor muscles in flexion (p < 0.01, d = 0.9) and extension tests (p < 0.05, d = 0.7). In conclusion, the volleyball players exhibited higher peak strength, despite the fact that the gymnasts showed greater muscle activity during the maximum voluntary contraction.

Effect of muscle glycogen content on exercise-induced changes in muscle T2 times

1998 ◽  
Vol 84 (4) ◽  
pp. 1178-1184 ◽  
Author(s):  
Thomas B. Price ◽  
John C. Gore
Keyword(s):  
Magnetic Resonance ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Transverse Relaxation Time ◽  
Voluntary Contraction ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Imaging Mri ◽  
Exercise Induced ◽  
Phosphorus Metabolites ◽  
Induced Changes

Effects of gastrocnemius glycogen (Gly) concentration on changes in transverse relaxation time (T2; ms) were studied after 5-min plantar flexion at 25% of maximum voluntary contraction (MVC). Gastrocnemius Gly, phosphorus metabolites, and T2 were measured in seven subjects by using interleaved13C/31P magnetic resonance spectroscopy (MRS) at 4.7 T and magnetic resonance imaging (MRI; 1.5 T). After baseline MRS/MRI, subjects exercised for 5 min at 25% of MVC and were reexamined (MRS/MRI). Subjects then performed ∼15 min of single-leg toe raises (50 ± 2% of MVC), depleting gastrocnemius Gly by 43%. After a 1-h rest (for T2 return to baseline), subjects repeated the 5-min protocol, followed by a final MRI/MRS. After the initial 5-min protocol, T2 values increased by 5.9 ± 0.8 ms (29.9 ± 0.4 to 35.8 ± 0.6 ms), whereas Gly did not change significantly (70.5 ± 6.8 to 67.6 ± 7.4 mM). After 15 min of toe raises, gastrocnemius Gly was reduced to 40.4 ± 5.3 mM ( P ≤ 0.01), recovering to 45.8 ± 5.3 mM ( P ≤ 0.05) during a 1-h rest. After the second 5-min bout of plantar flexion (reduced Gly at 25% of MVC), T2 values increased by 5.0 ± 0.8 ms (30.4 to 35.4 ms), whereas muscle Gly rose to 57.6 ± 5.3 mM. We conclude that muscle Gly concentration per se does not affect exercise-induced T2 increases in the human gastrocnemius.

Impaired neuromuscular function during isometric, shortening, and lengthening contractions after exercise-induced damage to elbow flexor muscles

2008 ◽  
Vol 105 (2) ◽  
pp. 502-509 ◽  
Author(s):  
Tanya S. Turner ◽  
Kylie J. Tucker ◽  
Nigel C. Rogasch ◽  
John G. Semmler
Keyword(s):  
Eccentric Exercise ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Elbow Flexor ◽  
Fine Motor ◽  
Triceps Brachii ◽  
Lengthening Contractions ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
Exercise Induced

The purpose of this study was to examine the effect of exercise-induced damage of the elbow flexor muscles on steady motor performance during isometric, shortening, and lengthening contractions. Ten healthy individuals (age 22 ± 4 yr) performed four tasks with the elbow flexor muscles: a maximum voluntary contraction, a one repetition maximum (1 RM), an isometric task at three joint angles (short, intermediate, and long muscle lengths), and a constant-load task during slow (∼7°/s) shortening and lengthening contractions. Task performance was quantified as the fluctuations in wrist acceleration (steadiness), and electromyography was obtained from the biceps and triceps brachii muscles at loads of 10, 20, and 40% of 1 RM. Tasks were performed before, immediately after, and 24 h after eccentric exercise that resulted in indicators of muscle damage. Maximum voluntary contraction force and 1-RM load declined by ∼45% immediately after exercise and remained lower at 24 h (∼30% decrease). Eccentric exercise resulted in reduced steadiness and increased biceps and triceps brachii electromyography for all tasks. For the isometric task, steadiness was impaired at the short compared with the long muscle length immediately after exercise ( P < 0.01). Furthermore, despite no differences before exercise, there was reduced steadiness for the shortening compared with the lengthening contractions after exercise ( P = 0.01), and steadiness remained impaired for shortening contractions 24 h later ( P = 0.01). These findings suggest that there are profound effects for the performance of these types of fine motor tasks when recovering from a bout of eccentric exercise.

scholarly journals Development of a trunk motor paradigm for use in neuroimaging

2020 ◽  
Vol 11 (1) ◽  
pp. 193-200
Author(s):  
Elizabeth Saunders ◽  
Brian C. Clark ◽  
Leatha A. Clark ◽  
Dustin R. Grooms
Keyword(s):  
Motor Control ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Erector Spinae ◽  
Head Motion ◽  
Low Back ◽  
Cyclic Contraction ◽  
Cyclic Contractions ◽  
Measurement Units ◽  
Healthy Participants

AbstractThe purpose of this study was to quantify head motion between isometric erector spinae (ES) contraction strategies, paradigms, and intensities in the development of a neuroimaging protocol for the study of neural activity associated with trunk motor control in individuals with low back pain. Ten healthy participants completed two contraction strategies; (1) a supine upper spine (US) press and (2) a supine lower extremity (LE) press. Each contraction strategy was performed at electromyographic (EMG) contraction intensities of 30, 40, 50, and 60% of an individually determined maximum voluntary contraction (MVC) (±10% range for each respective intensity) with real-time, EMG biofeedback. A cyclic contraction paradigm was performed at 30% of MVC with US and LE contraction strategies. Inertial measurement units (IMUs) quantified head motion to determine the viability of each paradigm for neuroimaging. US vs LE hold contractions induced no differences in head motion. Hold contractions elicited significantly less head motion relative to cyclic contractions. Contraction intensity increased head motion in a linear fashion with 30% MVC having the least head motion and 60% the highest. The LE hold contraction strategy, below 50% MVC, was found to be the most viable trunk motor control neuroimaging paradigm.

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