Changes in human skeletal muscle ultrastructure and force production after acute resistance exercise

1995 ◽  
Vol 78 (2) ◽  
pp. 702-708 ◽  
Author(s):  
M. J. Gibala ◽  
J. D. MacDougall ◽  
M. A. Tarnopolsky ◽  
W. T. Stauber ◽  
A. Elorriaga
Keyword(s):  
Resistance Exercise ◽  
Human Skeletal Muscle ◽  
Biceps Brachii ◽  
Force Production ◽  
The Other ◽  
Sample Analysis ◽  
Repetition Maximum ◽  
Muscle Ultrastructure ◽  
Single Bout ◽  
Before And After

Muscle ultrastructure and contractile properties were examined before and after a single bout of resistance exercise (8 sets of 8 repetitions at 80% of 1 repetition maximum). Eight untrained males performed the concentric (Con) phase of arm-curl exercise with one arm and the eccentric (Ecc) phase with the other arm. Needle biopsies were obtained from biceps brachii before exercise (Base), immediately postexercise from each arm (post-Con and post-Ecc), and 48 h postexercise from each arm (48 h-Con and 48 h-Ecc). Electron microscopy was used to quantify the presence of disrupted fibers in each sample. Analysis of variance revealed a greater (P < or = 0.05) proportion of disrupted fibers in post-Con, post-Ecc, 48 h-Con, and 48 h-Ecc samples compared with Base. Significantly more fibers were disrupted in post-Ecc (82%) and 48 h-Ecc (80%) samples compared with post-Con (33%) and 48 h-Con (37%), respectively. Voluntary and evoked strength measurements recovered to Base values within 24 h in the Con arm but remained depressed (P < or = 0.05) for 72–96 h in the Ecc arm. These data indicate that both the raising and lowering phases of weightlifting produced myofibrillar disruption, with the greatest disruption occurring during the lowering phase.

scholarly journals Is There an Issuance Premium for SRI Bonds?: Evidence from the Periods Before and After the COVID-19 Outbreak

2021 ◽  
Vol 50 (4) ◽  
pp. 369-409
Author(s):  
Hak-Kyum Kim ◽  
Hee-Joon Ahn
Keyword(s):  
Social Bonds ◽  
Bond Market ◽  
The Other ◽  
Bond Markets ◽  
Sample Analysis ◽  
Socially Responsible ◽  
Responsible Investment ◽  
South Korean ◽  
Before And After ◽  
Empirical Approaches

This study empirically examines whether there are any issuance premia for Socially Responsible Investment (SRI) bonds, using the data from the South Korean bond market from May 2018 to December 2020. We classify SRI bonds into three types: green, social, and sustainability. We divide the sample period into pre-COVID-19 and post-COVID-19 to understand how the pandemic has impacted the pricing of SRI bonds. We employ two empirical approaches: a matching sample analysis and a regression analysis that controls various bond and market characteristics. We find the following. First, significant issuance premia of at least 8bp existed for our sample of social bonds. However, we do not find any evidence of an issuance premium from the other two types of bonds. The premia on social bonds decreased significantly after the outbreak of COVID-19. As most studies have focused on green bonds, the literature on SRI bonds has largely been silent about social bonds and sustainability bonds. By focusing on these two less researched SRI bond types in addition to green bonds, we help expand our knowledge on SRI bond markets. Moreover, to the best of our knowledge, this is the first study to examine the SRI bond market in South Korea.

scholarly journals Effects of Single versus Multiple Bouts of Resistance Training on Maximal Strength and Anaerobic Performance

2018 ◽  
Vol 62 (1) ◽  
pp. 231-240 ◽  
Author(s):  
Kai Shiau ◽  
Te Hung Tsao ◽  
Chang Bin Yang
Keyword(s):  
Resistance Training ◽  
Resistance Exercise ◽  
Bench Press ◽  
Upper Body ◽  
Anaerobic Performance ◽  
Maximal Strength ◽  
Post Intervention ◽  
Significant Difference ◽  
Single Bout ◽  
Before And After

Abstract This study examined the effects of one single bout daily versus triple bouts of resistance exercise for 12 weeks on muscular strength and anaerobic performance of the upper body. Twenty young male adults (age: 22.0 ± 1.0 years, bench press: 44.0 ± 10.3 kg) were randomly assigned to a single bout (SB) or triple bouts (TB) of resistance exercise group. Maximal strength and anaerobic performance of the upper body using the bench press (one-repetition maximum) and the modified 30 s Wingate test were determined before and after the intervention. Additionally, changes in lactate levels before and after the Wingate test were measured. Although the SB and TB groups showed a significant increase in maximal strength (post-intervention, SB: 67.2 ± 9.2 and TB: 67.6 ± 7.6 kg, respectively) compared with the values at pre-intervention (SB: 44.6 ± 11.4 and TB: 43.9 ± 8.7 kg, respectively), there was no significant difference for this variable between the two groups post-intervention (p > 0.05). The anaerobic performance of the upper body in the SB and TB groups also displayed improvements without significant difference between the two groups after the completion of different training regimes. On the basis of the same training volume, multiple bouts of resistance training showed similar improvements in maximal strength and anaerobic performance to one bout of resistance training in young adult men without prior experience in resistance training

scholarly journals Effects of Ischemic Preconditioning as a Warm-Up on Leg Press and Bench Press Performance

2020 ◽  
Vol 75 (1) ◽  
pp. 267-277
Author(s):  
Luiz Guilherme da Silva Telles ◽  
Luiz Cristiano Carelli ◽  
Igor Dutra Bráz ◽  
Christian Junqueira ◽  
Estêvão Rios Monteiro ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Ischemic Preconditioning ◽  
Bench Press ◽  
The Other ◽  
Acute Effects ◽  
Warm Up ◽  
Repetition Maximum ◽  
Healthy Men ◽  
Leg Press ◽  
Press Performance

Abstract Ischemic preconditioning (IPC) has been used to increase performance in sports. The aim of this study was to compare the acute effects of IPC with different warm-up methods on the number of repetitions and total volume in resistance exercise (RE). Sixteen healthy men recreationally trained in RE participated in this study. After the anthropometric evaluation and familiarization, a one-repetition maximum (1RM) test and retest were performed in the bench press (BP) and in the leg press 45° (LP) exercise. After these tests, participants were randomly assigned to one of the five protocols: a) IPC; b) SHAM; c) a specific warm-up (SW); d) aerobic exercise (AE), and e) active stretching (AS) prior to performing 3 sets at 80% 1RM until concentric failure. The number of repetitions was higher following IPC compared to the SW following three sets both for the BP and LP. Similarly, the number of repetitions for IPC was higher in comparison to SHAM following three sets for the LP. The number of repetitions was higher following IPC compared to AE following 1st and 2nd sets for the LP and following the 2nd set for the BP. Finally, the number of repetitions was higher following IPC compared to AS following 1st and 2nd sets for the LP. The total volume was higher following IPC compared to SHAM, SW, AE, and AS for both the BP and LP. The IPC protocol increased the number of maximum repetitions and the total volume when compared to the other tested methods, thus indicating a better utilization during the pre-work warm-up. These results indicate positive associative responses to IPC with performance maintenance, which is of importance for both athletes and coaches.

STAT3 signaling is activated in human skeletal muscle following acute resistance exercise

2007 ◽  
Vol 102 (4) ◽  
pp. 1483-1489 ◽  
Author(s):  
Marissa K. Trenerry ◽  
Kate A. Carey ◽  
Alister C. Ward ◽  
David Cameron-Smith
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Human Skeletal Muscle ◽  
Negative Regulator ◽  
Common Element ◽  
Cytokine Signaling ◽  
Early Recovery ◽  
Stat3 Signaling ◽  
Stat3 Phosphorylation ◽  
Single Bout

The transcription factor signal transducer and activator of transcription 3 (STAT3) has been identified as a mediator of cytokine signaling and implicated in hypertrophy; however, the importance of this pathway following resistance exercise in human skeletal muscle has not been investigated. In the present study, the phosphorylation and nuclear localization of STAT3, together with STAT3-regulated genes, were measured in the early recovery period following intense resistance exercise. Muscle biopsy samples from healthy subjects (7 males, 23.0 + 0.9 yr) were harvested before and again at 2, 4, and 24 h into recovery following a single bout of maximal leg extension exercise (3 sets, 12 repetitions). Rapid and transient activation of phosphorylated (tyrosine 705) STAT3 was observed at 2 h postexercise. STAT3 phosphorylation paralleled the transient localization of STAT3 to the nucleus, which also peaked at 2 h postexercise. Downstream transcriptional events regulated by STAT3 activation peaked at 2 h postexercise, including early responsive genes c-FOS (800-fold), JUNB (38-fold), and c-MYC (140-fold) at 2 h postexercise. A delayed peak in VEGF (4-fold) was measured 4 h postexercise. Finally, genes associated with modulating STAT3 signaling were also increased following exercise, including the negative regulator SOCS3 (60-fold). Thus, following a single bout of intense resistance exercise, a rapid phosphorylation and nuclear translocation of STAT3 are evident in human skeletal muscle. These data suggest that STAT3 signaling is an important common element and may contribute to the remodeling and adaptation of skeletal muscle following resistance exercise.

Effects of training on postexercise limb muscle EMG synchronous to respiration

1979 ◽  
Vol 46 (6) ◽  
pp. 1093-1095 ◽  
Author(s):  
H. Kisselkova ◽  
V. Georgiev
Keyword(s):  
University Students ◽  
Biceps Brachii ◽  
Bicycle Ergometer ◽  
The Other ◽  
Limb Muscle ◽  
Bioelectric Activity ◽  
Functional Diagnosis ◽  
The Third ◽  
Disappearance Time ◽  
Before And After

Twenty university students (10 trained and 10 untrained) participated in 60 sessions testing the effect of training on postexercise electromyogram synchronous to respiration. The latter was recorded for m. biceps brachii dextra, m. quadriceps femoris dextra, and m. gastrocnemium dextra. The respiration rate was taken before and after three levels of functional effort performed on a bicycle ergometer. The first (2 X 30 s with a 20-s interval at 100 rpm and 245 W) and the second (5 X 1 min with a 30-s interval after each min, at 90 rpm and 200 W) were of speed-developing nature; the third (20 min at 60 rpm and 117 W with 1-min interval every 5 min) was to develop endurance. Our observations show that the greatest percentage of a synchronous-to-respiration muscle bioelectric activity can be observed after the first two types of effort. In the third type the percentage is smaller and the duration of the activity is shorter. On the other hand, the percentage of biopotential occurrence is greater for untrained persons, with a considerable longer disappearance time. The phenomenon can be used as a criterion in the athlete's functional diagnosis.

scholarly journals The Effect of Grip Width on Muscle Strength and Electromyographic Activity in Bench Press among Novice- and Resistance-Trained Men

2021 ◽  
Vol 18 (12) ◽  
pp. 6444
Author(s):  
Atle Hole Saeterbakken ◽  
Nicolay Stien ◽  
Helene Pedersen ◽  
Tom Erik Jorung Solstad ◽  
Kristoffer Toldnes Cumming ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Muscle Activity ◽  
Bench Press ◽  
Biceps Brachii ◽  
The Other ◽  
Electromyographic Activity ◽  
Triceps Brachii ◽  
Repetition Maximum ◽  
Anterior Deltoid ◽  
Group Comparisons

Background: This study compared the muscle activity and six repetition maximum (6-RM) loads in bench press with narrow, medium, and wide grip widths with sub-group comparisons of resistance-trained (RT) and novice-trained (NT) men. Methods: After two familiarization sessions, twenty-eight subjects lifted their 6-RM loads with the different grip widths with measurement of electromyographic activity. Results: Biceps brachii activity increased with increasing grip width, whereas wide grip displayed lower triceps brachii activation than medium and narrow. In the anterior deltoid, greater activity was observed using a medium compared to narrow grip. Similar muscle activities were observed between the grip widths for the other muscles. For the RT group, greater biceps brachii activity with increasing grip width was observed, but only greater activity was observed in the NT group between narrow and wide. Comparing wide and medium grip width, the RT group showed lower triceps activation using a wide grip, whereas the NT group showed lower anterior deltoid activation using a narrow compared to medium grip. Both groups demonstrated lower 6-RM loads using a narrow grip compared to the other grips. Conclusion: Grip widths affect both 6-RM loads and triceps brachii, biceps brachii, and anterior deltoid activity especially between wide and narrow grip widths.

Resistance exercise increases NF-κB activity in human skeletal muscle

2012 ◽  
Vol 302 (6) ◽  
pp. R667-R673 ◽  
Author(s):  
Luke Vella ◽  
Marissa K. Caldow ◽  
Amy E. Larsen ◽  
Daniella Tassoni ◽  
Paul A. Della Gatta ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dna Binding ◽  
Inflammatory Response ◽  
Resistance Exercise ◽  
Muscle Biopsy ◽  
Human Skeletal Muscle ◽  
Control Group ◽  
Promoter Regions ◽  
Protein Levels ◽  
Single Bout

Intense resistance exercise causes a significant inflammatory response. NF-κB has been identified as a prospective key transcription factor mediating the postexercise inflammatory response. The purpose of this study was to determine whether a single bout of intense resistance exercise regulates NF-κB signaling in human skeletal muscle. Muscle biopsy samples were obtained from the vastus lateralis of five recreationally active, but not strength-trained, males (21.9 ± 1.3 yr) prior to, and at 2 and 4 h following, a single bout of intense resistance exercise. A further five subjects (4 males, 1 female) (23 ± 0.89 yr) were recruited as a nonexercise control group to examine the effect of the muscle biopsy protocol on key markers of skeletal muscle inflammation. Protein levels of IκBα and phosphorylated NF-κB (p65), as well as the mRNA expression of inflammatory myokines monocyte chemoattractant protein 1 (MCP-1), IL-6, and IL-8 were measured. Additionally, NF-κB (p65) DNA binding to the promoter regions of MCP-1, IL-6, and IL-8 was investigated. IκBα protein levels decreased, while p-NF-κB (p65) protein levels increased 2 h postexercise and returned to near-baseline levels by 4-h postexercise. Immunohistochemical data verified these findings, illustrating an increase in p-NF-κB (p65) protein levels, and nuclear localization at 2 h postexercise. Furthermore, NF-κB DNA binding to MCP-1, IL-6, and IL-8 promoter regions increased significantly 2 h postexercise as did mRNA levels of these myokines. No significant change was observed in the nonexercise control group. These novel data provide evidence that intense resistance exercise transiently activates NF-κB signaling in human skeletal muscle during the first few hours postexercise. These findings implicate NF-κB in the transcriptional control of myokines known to be central to the postexercise inflammatory response.

scholarly journals The effect of exercise and insulin on AS160 phosphorylation and 14-3-3 binding capacity in human skeletal muscle

2008 ◽  
Vol 294 (2) ◽  
pp. E401-E407 ◽  
Author(s):  
Kirsten F. Howlett ◽  
Alicia Mathews ◽  
Andrew Garnham ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Acute Exercise ◽  
Binding Capacity ◽  
Sensitivity Index ◽  
Akt Phosphorylation ◽  
Prior Exercise ◽  
Single Bout ◽  
Before And After ◽  
Amp Activated Protein Kinase

AS160 is an Akt substrate of 160 kDa implicated in the regulation of both insulin- and contraction-mediated GLUT4 translocation and glucose uptake. The effects of aerobic exercise and subsequent insulin stimulation on AS160 phosphorylation and the binding capacity of 14-3-3, a novel protein involved in the dissociation of AS160 from GLUT4 vesicles, in human skeletal muscle are unknown. Hyperinsulinemic-euglycemic clamps were performed on seven men at rest and immediately and 3 h after a single bout of cycling exercise. Skeletal muscle biopsies were taken before and after the clamps. The insulin sensitivity index calculated during the final 30 min of the clamp was 8.0 ± 0.8, 9.1 ± 0.5, and 9.2 ± 0.8 for the rest, postexercise, and 3-h postexercise trials, respectively. AS160 phosphorylation increased immediately after exercise and remained elevated 3 h after exercise. In contrast, the 14-3-3 binding capacity of AS160 and phosphorylation of Akt and AMP-activated protein kinase were only increased immediately after exercise. Insulin increased AS160 phosphorylation and 14-3-3 binding capacity and insulin receptor substrate-1 and Akt phosphorylation, but the response to insulin was not enhanced by prior exercise. In conclusion, the 14-3-3 binding capacity of AS160 is increased immediately after acute exercise in human skeletal muscle, but this is not maintained 3 h after exercise completion despite sustained AS160 phosphorylation. Insulin increases AS160 phosphorylation and 14-3-3 binding capacity, but prior exercise does not appear to enhance the response to insulin.

scholarly journals Aging differentially affects human skeletal muscle microRNA expression at rest and after an anabolic stimulus of resistance exercise and essential amino acids

2008 ◽  
Vol 295 (6) ◽  
pp. E1333-E1340 ◽  
Author(s):  
Micah J. Drummond ◽  
John J. McCarthy ◽  
Christopher S. Fry ◽  
Karyn A. Esser ◽  
Blake B. Rasmussen
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Mirna Expression ◽  
Essential Amino Acid ◽  
Human Skeletal Muscle ◽  
Age Groups ◽  
Young Men ◽  
Essential Amino Acids ◽  
Before And After

Sarcopenia, skeletal muscle loss during aging, is associated with increased falls, fractures, morbidity, and loss of independence. MicroRNAs (miRNAs) are novel posttranscriptional regulators. The role of miRNAs in cell size regulation after an anabolic stimulus in human skeletal muscle is unknown. We hypothesized that aging would be associated with a differential expression of skeletal muscle primary miRNA (pri-miRNA) and mature miRNA (miR). To test this hypothesis, we used real-time PCR and immunoblotting before and after an anabolic stimulus (resistance exercise + ingestion of a 20-g leucine-enriched essential amino acid solution) to measure the expression of muscle-specific miRNAs (miR-1, miR-133a, and miR-206), upstream regulators (MyoD and myogenin), and downstream targets [insulin-like growth factor-I, histone deacetylase-4, myocyte enhancing factor-2, and Ras homolog enriched in brain (Rheb)] in skeletal muscle of young and older men. Muscle biopsies were obtained at baseline and 3 and 6 h after exercise. At baseline, we found pri-miRNA-1-1, -1-2, -133a-1, and -133a-2 expression elevated in older compared with young men ( P < 0.05). Pri-miRNA-1-2, -133a-1, and -133a-2 were reduced at 6 h after exercise only in the young men compared with baseline, whereas pri-miRNA-206 was elevated at different postexercise time points in older and young men ( P < 0.05). Compared with baseline, miR-1 was reduced only in the young men, whereas Rheb protein was increased in both age groups after the anabolic stimulus ( P < 0.05). We conclude that skeletal muscle primary and mature miRNA expression in young men is readily altered by an anabolic stimulus of resistance exercise + essential amino acid ingestion. However, aging is associated with higher basal skeletal muscle primary miRNA expression and a dysregulated miRNA response after the anabolic stimulus.

Weekly Exercise Consistently Reinstates Positive Mood

1998 ◽  
Vol 3 (4) ◽  
pp. 271-280 ◽  
Author(s):  
Hannah Steinberg ◽  
Briony R. Nicholls ◽  
Elizabeth A. Sykes ◽  
N. LeBoutillier ◽  
Nerina Ramlakhan ◽  
...  
Keyword(s):  
Physical Exercise ◽  
Negative Mood ◽  
Real Life ◽  
Positive Mood ◽  
Field Investigation ◽  
Single Bout ◽  
Before And After ◽  
Exercise Class ◽  
Negative Feelings ◽  
Over Time

Mood improvement immediately after a single bout of exercise is well documented, but less is known about successive and longer term effects. In a “real-life” field investigation, four kinds of exercise class (Beginners, Advanced, Body Funk and Callanetics) met once a week for up to 7 weeks. Before and after each class the members assessed how they felt by completing a questionnaire listing equal numbers of “positive” and “negative” mood words. Subjects who had attended at least five times were included in the analysis, which led to groups consisting of 18, 20, 16, and 16 subjects, respectively. All four kinds of exercise significantly increased positive and decreased negative feelings, and this result was surprisingly consistent in successive weeks. However, exercise seemed to have a much greater effect on positive than on negative moods. The favorable moods induced by each class seemed to have worn off by the following week, to be reinstated by the class itself. In the Callanetics class, positive mood also improved significantly over time. The Callanetics class involved “slower,” more demanding exercises, not always done to music. The Callanetics and Advanced classes also showed significantly greater preexercise negative moods in the first three sessions. However, these differences disappeared following exercise. Possibly, these two groups had become more “tolerant” to the mood-enhancing effects of physical exercise; this may be in part have been due to “exercise addiction.”

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