AMP kinase expression and activity in human skeletal muscle: effects of immobilization, retraining, and creatine supplementation

2005 ◽  
Vol 98 (4) ◽  
pp. 1228-1233 ◽  
Author(s):  
Bert O. Eijnde ◽  
Wim Derave ◽  
Jørgen F. P. Wojtaszewski ◽  
Erik A. Richter ◽  
Peter Hespel
Keyword(s):  
Protein Expression ◽  
Vastus Lateralis ◽  
Creatine Supplementation ◽  
Knee Extensor ◽  
Double Blind ◽  
Α Subunit ◽  
Beneficial Effects ◽  
Before And After ◽  
Subunit Expression ◽  
The Right

The effects of leg immobilization and retraining in combination with oral creatine intake on muscle AMP-activated protein kinase (AMPK) protein expression and phosphorylation status were investigated. A double-blind trial was performed in young healthy volunteers ( n = 22). A cast immobilized the right leg for 2 wk, whereafter the knee-extensor muscles of that leg were retrained for 6 wk. Half of the subjects received creatine monohydrate throughout the study (Cr; from 15 g down to 2.5 g daily), and the others ingested placebo (P; maltodextrin). Before and after immobilization and retraining, needle biopsies were taken from the right and left vastus lateralis muscles. In the right leg of P and Cr, immobilization did not affect AMPK α1-, α2-, and β2-subunit expression or AMPK α-subunit phosphorylation status. However, irrespective of the treatment received, retraining increased the degree of α-subunit phosphorylation by ∼25% ( P < 0.05) and increased AMPK α1-subunit expression ( P < 0.05) in both groups. From the start to the end of the study, AMPK subunit protein expression and α-subunit phosphorylation status were unchanged in the contralateral control leg. It is concluded that immobilization-induced muscle inactivity for 2 wk does not alter AMPK α1-, α2-, and β2-subunit expression or α-AMPK phosphorylation status. Furthermore, the present observations indicate that AMPK probably is not implicated in the previously reported beneficial effects of oral creatine supplementation on muscle during immobilization and rehabilitative weight training.

Effects of creatine supplementation and exercise training on fitness in men 55–75 yr old

2003 ◽  
Vol 95 (2) ◽  
pp. 818-828 ◽  
Author(s):  
Bert O. Eijnde ◽  
Marc Van Leemputte ◽  
Marina Goris ◽  
Valery Labarque ◽  
Youri Taes ◽  
...  
Keyword(s):  
Exercise Training ◽  
Physical Fitness ◽  
Vastus Lateralis ◽  
Creatine Supplementation ◽  
Knee Extensor ◽  
Isometric Strength ◽  
Fat Free Mass ◽  
Endurance Capacity ◽  
Double Blind

effect of oral creatine supplementation (CR; 5 g/day) in conjunction with exercise training on physical fitness was investigated in men between 55 and 75 yr of age ( n = 46). A double-blind randomized placebo-controlled (PL) trial was performed over a 6-mo period. Furthermore, a subgroup ( n = 20) completed a 1-yr follow-up. The training program consisted of cardiorespiratory endurance training as well as moderate resistance training (2–3 sessions/wk). Endurance capacity was evaluated during a maximal incremental bicycle ergometer test, maximal isometric strength of the knee-extensor muscles was assessed by an isokinetic dynamometer, and body composition was assessed by hydrostatic weighing. Furthermore, in a subgroup (PL: n = 13; CR: n = 12) biopsies were taken from m. vastus lateralis to determine total creatine (TCr) content. In PL, 6 mo of training increased peak oxygen uptake rate (+16%; P < 0.05). Fat-free mass slightly increased (+0.3 kg; P < 0.05), whereas percent body fat slightly decreased (-1.2%; P < 0.05). The training intervention did not significantly change either maximal isometric strength or body weight. The responses were independent of CR. Still, compared with PL, TCr was increased by ∼5% in CR, and this increase was closely correlated with initial muscle creatine content ( r = -0.78; P < 0.05). After a 1-yr follow-up, muscle TCr was not higher in CR than in PL. Furthermore, the other measurements were not affected by CR. It is concluded that long-term creatine intake (5 g/day) in conjunction with exercise training does not beneficially impact physical fitness in men between 55 and 75 yr of age.

Effects of Creatine Loading on Electromyographic Fatigue Threshold in Cycle Ergometry in College-Age Men

2008 ◽  
Vol 18 (2) ◽  
pp. 142-151 ◽  
Author(s):  
Ashley A. Walter ◽  
Abbie E. Smith ◽  
Trent J. Herda ◽  
Eric D. Ryan ◽  
Jordan R. Moon ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Cycle Ergometer ◽  
Fatigue Threshold ◽  
Double Blind Study ◽  
Double Blind ◽  
College Age ◽  
Cycle Ergometer Test ◽  
Before And After ◽  
The Right ◽  
Ergometer Test

The purpose of this study was to examine the effects of 5 d of creatine (Cr) loading on the electromyographic fatigue threshold (EMG FT) in college-age men. Sixteen men (age 22.4 ± 2.6 yr, height 177.4 ± 6.8 cm, weight 79.5 ± 10.6 kg; M ± SD) participated in this double-blind study and were randomly placed into either placebo (Pl; 10 g of flavored fructose powder per packet; n = 8) or Cr (5 g dicreatine citrate plus 10 g of flavored fructose powder per packet; n = 8) loading groups. Each participant ingested 1 packet 4 times/d, totaling 20 g/d for 5 days (loading). Before and after loading, each participant performed a discontinuous cycle-ergometer test to determine his EMG FT, using bipolar surface electrodes placed on the vastus lateralis of the right thigh. Four 60-s work bouts (ranging from 200 to 400 W) were completed. Adequate rest was given between bouts to allow for the participants’ heart rate (HR) to drop within 10 beats of their resting HR. The EMG amplitude was averaged over 5-s intervals for each 60-s work bout. Resulting slopes from each successive work bout were used to calculate EMG FT. A 2-way ANOVA, Group (Cr vs. Pl) EETime (pre vs. post), resulted in a nonsignificant (p > .05) interaction for supplement and time. In addition, a significant increase (p = .009) in weight was observed in the Cr group. These data suggest that there was a minimal influence of Cr loading on EMG FT for the participants in this study.

scholarly journals Regional and muscle-specific adaptations in knee extensor hypertrophy using flywheel versus conventional weight-stack resistance exercise

2019 ◽  
Vol 44 (8) ◽  
pp. 827-833 ◽  
Author(s):  
Tommy R. Lundberg ◽  
Maria T. García-Gutiérrez ◽  
Mirko Mandić ◽  
Mats Lilja ◽  
Rodrigo Fernandez-Gonzalo
Keyword(s):  
Resistance Exercise ◽  
Muscle Hypertrophy ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Knee Extensors ◽  
Cross Sectional ◽  
Proximal Site ◽  
Before And After

This study compared the effects of the most frequently employed protocols of flywheel (FW) versus weight-stack (WS) resistance exercise (RE) on regional and muscle-specific adaptations of the knee extensors. Sixteen men (n = 8) and women (n = 8) performed 8 weeks (2–3 days/week) of knee extension RE employing FW technology on 1 leg (4 × 7 repetitions), while the contralateral leg performed regular WS training (4 × 8–12 repetitions). Maximal strength (1-repetition maximum (1RM) in WS) and peak FW power were determined before and after training for both legs. Partial muscle volume of vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF) were measured using magnetic resonance imaging. Additionally, quadriceps cross-sectional area was assessed at a proximal and a distal site. There were no differences (P > 0.05) between FW versus WS in muscle hypertrophy of the quadriceps femoris (8% vs. 9%), VL (10% vs. 11%), VM (6% vs. 8%), VI (5% vs. 5%), or RF (17% vs. 17%). Muscle hypertrophy tended (P = 0.09) to be greater at the distal compared with the proximal site, but there was no interaction with exercise method. Increases in 1RM and FW peak power were similar across legs, yet the increase in 1RM was greater in men (31%) than in women (20%). These findings suggest that FW and WS training induces comparable muscle-specific hypertrophy of the knee extensors. Given that these robust muscular adaptations were brought about with markedly fewer repetitions in the FW compared with WS, it seems FW training can be recommended as a particularly time-efficient exercise paradigm.

scholarly journals Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Javier Zaragoza ◽  
Grant Tinsley ◽  
Stacie Urbina ◽  
Katelyn Villa ◽  
Emily Santos ◽  
...  
Keyword(s):  
Physical Performance ◽  
Linear Models ◽  
Dynamic Testing ◽  
Collegiate Athletes ◽  
Performance Testing ◽  
The Body ◽  
Double Blind ◽  
Movement Accuracy ◽  
Beneficial Effects ◽  
Before And After

Abstract Background A limited amount of research has demonstrated beneficial effects of caffeine and theanine supplementation for enhancement of mental performance. The purpose of this investigation was to determine whether the acute ingestion of a supplement containing caffeine, theanine and tyrosine improves mental and physical performance in athletes. Methods Twenty current or former male collegiate athletes (age: 20.5 ± 1.4 y; height: 1.82 ± 0.08 m; weight: 83.9 ± 12.6 kg; body fat: 13.8 ± 5.6%) completed this randomized, double-blind, placebo-controlled crossover trial. After familiarization, each participant completed two identical testing sessions with provision of a proprietary dietary supplement (SUP) containing caffeine theanine and tyrosine or a placebo (PL). Within each testing session, participants completed assessments of mental and physical performance before and after provision of SUP or PL, as well as after two rounds of exercise. Assessments were performed using a performance testing device (Makoto Arena) that evaluated multiple aspects of mental and physical performance in response to auditory and visual stimuli. Testing was performed both with the body in a static position and during dynamic movement. General linear models were used to evaluate the effects of SUP and PL on performance. Results Changes in movement accuracy during performance assessment were greater following SUP ingestion as compared to PL for both static and dynamic testing (SUP: + 0.4 to 7.5%; PL: − 1.4 to 1.4% on average; p < 0.05). For dynamic testing, the change in number of targets hit was higher and the change in average hit time was lower with SUP as compared to PL (p < 0.05). However, there were no differences between conditions for the changes in number of targets hit or average hit time during static testing. There were no differences in changes of subjective variables during either condition, and performance measures during the two rounds of exercise did not differ between conditions (p > 0.05). Discussion The present results indicate that a combination of a low-dose of caffeine with theanine and tyrosine may improve athletes’ movement accuracy surrounding bouts of exhaustive exercise without altering subjective variables. Based on this finding, supplementation with caffeine, theanine and tyrosine could potentially hold ergogenic value for athletes in sports requiring rapid and accurate movements. Trial registration NCT03019523. Registered 24 January 2017.

Carbohydrate Supplementation Attenuates Muscle Glycogen Loss during Acute Bouts of Resistance Exercise

2000 ◽  
Vol 10 (3) ◽  
pp. 326-339 ◽  
Author(s):  
G. Gregory Haff ◽  
Alexander J. Koch ◽  
Jeffrey A. Potteiger ◽  
Karen E. Kuphal ◽  
Lawrence M. Magee ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Body Mass ◽  
Muscle Glycogen ◽  
Vastus Lateralis ◽  
Placebo Treatment ◽  
Double Blind ◽  
Isokinetic Test ◽  
Before And After ◽  
Leg Exercise ◽  
Wet Weight

The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.

Molecular basis of species-specific expression of repolarizing K+ currents in the heart

2003 ◽  
Vol 285 (4) ◽  
pp. H1641-H1649 ◽  
Author(s):  
Stephen Zicha ◽  
Isaac Moss ◽  
Bruce Allen ◽  
Andras Varro ◽  
Julius Papp ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Protein Expression ◽  
Guinea Pigs ◽  
Delayed Rectifier ◽  
Important Species ◽  
Α Subunit ◽  
Delayed Rectifier Current ◽  
Mrna Concentration ◽  
Subunit Expression ◽  
Species Specific

There are important species-specific differences in K+ current profiles and arrhythmia susceptibility, but interspecies comparisons of K+ channel subunit expression are lacking. We quantified voltage-gated K+ channel (Kv) subunit mRNA and protein in rabbits, guinea pigs, and humans. Kv1.4, Kv4.2, and Kv4.3 mRNA was present in rabbits but undetectable in guinea pigs. MinK mRNA concentration in guinea pigs was almost threefold greater versus humans and 20-fold versus rabbits. MinK protein expression in guinea pigs was almost twofold that in humans and sixfold that in rabbits. KvLQT1 mRNA concentration was greatest in humans, and protein expression in humans was increased by ∼2- and ∼7-fold compared with values in rabbits and guinea pigs, respectively. The ether-a-go-go-related gene (ERG1) mRNA was more concentrated in humans, but ERG1 protein expression could not be compared across species because of epitope sequence differences. We conclude that important interspecies differences in cardiac K+ channel subunit expression exist and may contribute to the following: 1) lack of a transient outward current in the guinea pig (α-subunit transcription absent in the guinea pig heart); 2) small slow delayed rectifier current and torsades de pointes susceptibility in the rabbit (low-level minK expression); and 3) large slow component of the delayed rectifier current in the guinea pig (strong minK expression).

scholarly journals Effects of Foam Rolling Duration on Tissue Stiffness and Perfusion: A Randomized Cross-Over Trial

2021 ◽  
pp. 626-634
Author(s):  
Jan Schroeder ◽  
Jan Wilke ◽  
Karsten Hollander
Keyword(s):  
Blood Flow ◽  
Near Infrared ◽  
Tissue Perfusion ◽  
Minimal Detectable Change ◽  
Tissue Stiffness ◽  
Foam Rolling ◽  
Beneficial Effects ◽  
Before And After ◽  
The Right ◽  
The Impact

Despite its beneficial effects on flexibility and muscle soreness, there is still conflicting evidence regarding dose-response relationships and underlying mechanisms of foam rolling (FR). This study aimed to investigate the impact of different FR protocols on tissue perfusion and tissue stiffness. In a randomized crossover trial, two FR protocols (2x1 min, 2x3 min) were applied to the right anterior thigh of twenty healthy volunteers (11 females, 25 ± 4 years). Tissue perfusion (near infrared spectroscopy, NIRS) and stiffness (Tensiomyography, TMG and Myotonometry, MMT) were assessed before and after FR application. Variance analyses revealed a significant interaction of FR duration and tissue perfusion (F[1,19] = 7.098, p = 0.015). Local blood flow increased significantly from pre to post test (F[1,19] = 7.589, p = 0.013), being higher (Δ +9.7%) in the long-FR condition than in the short-FR condition (Δ +2.8%). Tissue stiffness (MMT) showed significant main effects for time (F[1,19] = 12.074, p = 0.003) and condition (F[1,19] = 7.165, p = 0.015) with decreases after short-FR (Δ -1.6%) and long-FR condition (Δ -1.9%). However, there was no time*dose-interaction (F[1,19] = 0.018, p = 0.895). No differences were found for TMG (p > 0.05). FR-induced changes failed to exceed the minimal detectable change threshold (MDC). Our data suggest that increased blood flow and altered tissue stiffness may mediate the effects of FR although statistical MDC thresholds were not achieved. Longer FR durations seem to be more beneficial for perfusion which is of interest for exercise professionals designing warm-up and cool-down regimes. Further research is needed to understand probable effects on parasympathetic outcomes representing systemic physiological responses to locally applied FR stimulations.

Mutable and immutable features of paw-shake responses after hindlimb deafferentation in the cat

1989 ◽  
Vol 62 (1) ◽  
pp. 162-173 ◽  
Author(s):  
G. F. Koshland ◽  
J. L. Smith
Keyword(s):  
Vastus Lateralis ◽  
Recovery Period ◽  
Knee Extensor ◽  
Burst Duration ◽  
Temporal Organization ◽  
Cycle Period ◽  
Lateral Gastrocnemius ◽  
Cycle Number ◽  
Before And After ◽  
Emg Electrodes

1. Hindlimb paw-shake responses were assessed before and after unilateral deafferentation (L3-S1) in chronic-spinal cats (n = 5), spinalized at the T12 level 1 yr earlier. Selected ankle flexor [tibialis anterior (TA)] and extensor [lateral gastrocnemius (LG)] and knee extensor [vastus lateralis (VL)] muscles were surgically implanted with chronic electromyographic (EMG) electrodes to determine mutable features of cycle characteristics and muscle synergies that are modulated by motion-dependent feedback as opposed to immutable features that are centrally programmed and not modulated by limb afference. 2. Paw-shake responses were difficult to elicit in the extensively deafferented hindlimb; this was true particularly during the first recovery weeks after deafferentation. By the end of the first month, however, brief responses of 1 or 2 cycles were commonly elicited in four of five cats, and responses of 3-7 cycles were common by the end of the second month in three of five cats. Initially, responses in the deafferented limb were elicited by stimuli applied to the dorsolateral thigh, an oval patch of skin innervated by intact S2 afferents. Over the 4-mo recovery period, however, the receptive field of the largely denervated skin expanded, and responses were also elicited by stimuli applied to the lateral aspect of the knee and shank, but usually not the paw. 3. In addition to fewer average cycles per response (5 vs. 10 cycles), paw shaking evoked in the deafferented hindlimb was characterized by longer-than-average cycle periods (124 vs. 98 ms), but the average cycle period varied widely among responses, ranging from 99 to 239 ms. Before deafferentation, the temporal organization of consecutive cycles was stereotypic; cycle periods increased linearly throughout a response. After deafferentation, however, there was no systematic relationship between cycle period and cycle number, and approximately 14% of the records with greater than or equal to 3 cycles were characterized by arhythmical sequences of EMG bursts. 4. At the ankle, LG burst duration was not altered by deafferentation, but TA onset and burst duration were affected. Before deafferentation, TA onset was invariant with respect to the beginning of the cycle, and burst duration increased linearly with cycle period. After deafferentation, however, TA onset was delayed, and the delay increased linearly with cycle period. Consequently, the TA burst duration was brief and unrelated to cycle period.(ABSTRACT TRUNCATED AT 400 WORDS)

The benefit of a supplement with the antioxidant melatonin on redox status and muscle damage in resistance-trained athletes

2017 ◽  
Vol 42 (7) ◽  
pp. 700-707 ◽  
Author(s):  
Roberto C. Leonardo-Mendonça ◽  
Javier Ocaña-Wilhelmi ◽  
Tomás de Haro ◽  
Carlos de Teresa-Galván ◽  
Eduardo Guerra-Hernández ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Muscle Damage ◽  
Antioxidant Properties ◽  
Redox Status ◽  
Absorption Capacity ◽  
Double Blind ◽  
Beneficial Effects ◽  
Before And After ◽  
High Doses ◽  
Exercise Induced

Previous data showed that the administration of high doses of melatonin improved the circadian system in athletes. Here, we investigated in the same experimental paradigm whether the antioxidant properties of melatonin has also beneficial effects against exercise-induced oxidative stress and muscle damage in athletes. Twenty-four athletes were treated with 100 mg·day−1 of melatonin or placebo 30 min before bedtime during 4 weeks in a randomized double-blind scheme. Exercise intensity was higher during the study that before starting it. Blood samples were collected before and after treatment, and plasma was used for oxygen radical absorption capacity (ORAC), lipid peroxidation (LPO), nitrite plus nitrate (NOx), and advanced oxidation protein products (AOPP) determinations. Glutathione (GSH), glutathione disulphide (GSSG) levels, and glutathione peroxidase (GPx) and reductase (GRd) activities, were measured in erythrocytes. Melatonin intake increased ORAC, reduced LPO and NOx levels, and prevented the increase of AOPP, compared to placebo group. Melatonin was also more efficient than placebo in reducing GSSG·GSH−1 and GPx·GRd−1 ratios. Melatonin, but not placebo, reduced creatine kinase, lactate dehydrogenase, creatinine, and total cholesterol levels. Overall, the data reflect a beneficial effect of melatonin treatment in resistance-training athletes, preventing extra- and intracellular oxidative stress induced by exercise, and yielding further skeletal muscle protection against exercise-induced oxidative damage.

scholarly journals Thyroid Hormone Increases mRNA and Protein Expression of Na+-K+-ATPase α2 and β1 Subunits in Human Skeletal Muscles

2007 ◽  
Vol 92 (1) ◽  
pp. 353-358 ◽  
Author(s):  
Bunyong Phakdeekitcharoen ◽  
Suchart Phudhichareonrat ◽  
Chathchai Pookarnjanamorakot ◽  
Chusak Kijkunasathian ◽  
Nattha Tubtong ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Protein Expression ◽  
Mrna Expression ◽  
Skeletal Muscles ◽  
Vastus Lateralis ◽  
Mrna Level ◽  
Before And After ◽  
Hyperthyroid Patients ◽  
Relative Mrna Expression ◽  
Human Skeletal Muscles

Abstract Context: Thyroid hormone regulates specific Na+-K+-ATPase isoforms in rodent skeletal muscles. No study has examined this relationship in human tissues. Objective: This study investigated the effect of hyperthyroid status on the expression of the α- and β-subunits of the Na+-K+-ATPase. Design: The vastus lateralis muscles from eight hyperthyroid patients were biopsied before and after treatment. Ten age-matched euthyroid subjects served as controls. Results: In hyperthyroid patients, the average T3 level was three times higher in pretreatment compared with posttreatment (262 ± 75 vs. 86 ± 21 ng/dl, P = 0.001). The relative mRNA expression of the α2, but not α1 or α3, subunit was increased approximately 3-fold in pretreatment (2.98 ± 0.52 vs. 0.95 ± 0.40, P &lt; 0.01), whereas that of β1, not β2 or β3, subunit was increased approximately 2.8-fold in pretreatment (2.83 ± 0.38 vs. 1.10 ± 0.27, P &lt; 0.01). The relative mRNA expression of the α2 and β1 subunits was positively correlated with the serum T3 (r = 0.75, P = 0.001 and r = 0.66, P = 0.003, respectively). Immunohistochemistry studies revealed an increase in protein abundance of the α2 and β1, but not α1 or β2, subunits in the plasma membrane of muscle fibers of hyperthyroid patients, which decreased after treatment. Conclusions: This provides the first evidence that, in human skeletal muscles, thyroid hormone up-regulates the Na+-K+-ATPase protein expression at least, in part, at mRNA level, and the α2 and β1 subunits play the important role in this regulation.

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