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1.
Effect of vitamin A administration on free radicals and lactate levels in individuals exercised to exhaustion.
Patlar, S, Baltaci, AK, Mogulkoc, R
Pakistan journal of pharmaceutical sciences. 2016;(5):1531-1534
Abstract
This study was performed to explore the effect of vitamin A administration on Free Radicals production and antioxidant system activity and lactate levels in individuals exercised to exhaustion The study registered 10 healthy sedentary males their mean age was 22,85±0,26 years. The subjects were orally administrated with 300 mg vitamin A (retinol) for 4 weeks and engaged in strenuous exercise (using the Bruce protocol) once a week. Blood samples were collected from the subjects at four different times, before and after the supplementation and before and after exercise to analyze Malondialdehyde (MDA), Nitric oxide (NO), Glutathione (GSH), Glutathione peroxidase (GSH-Px), Catalase (CAT), Superoxide dismutase (SOD) levels using colorimetric ELISA test kits and plasma lactate levels using an autoanalyzer. Exhaustion exercise leaded to an increase in both MDA, NO, and lactate, and GSH, GSH-Px, CAT and SOD levels compared to resting levels both before and after supplementation (p<0.05). Increased NO levels found in pre-supplementation exhaustion showed a significant decrease after the supplementation of vitamin A (p<0.05), but the other parameters were not changed after vitamin A administration. The results of our study demonstrate that the increase caused by 4-week strenuous exercise in the levels of the free radical NO was offset by vitamin A supplementation. It can be suggested that supplementation of vitamin A at physiological doses has a limited effect on lipid peroxidation caused by strenuous exercise.
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2.
Muscle damage and repeated bout effect induced by enhanced eccentric squats.
Coratella, G, Chemello, A, Schena, F
The Journal of sports medicine and physical fitness. 2016;(12):1540-1546
Abstract
BACKGROUND Muscle damage and repeated bout effect have been studied after pure eccentric-only exercise. The aim of this study was to evaluate muscle damage and repeated bout effect induced by enhanced eccentric squat exercise using flywheel device. METHODS Thirteen healthy males volunteered for this study. Creatine kinase blood activity (CK), quadriceps isometric peak torque and muscle soreness were used as markers of muscle damage. The dependent parameters were measured at baseline, immediately after and each day up to 96 hours after the exercise session. The intervention consisted of 100 repetitions of enhanced eccentric squat exercise using flywheel device. The same protocol was repeated after 4 weeks. RESULTS After the first bout, CK and muscle soreness were significantly greater (P<0.05) than baseline respectively up to 72 and 96 hours. Isometric peak torque was significantly lower (P<0.05) up to 72 hours. After the second bout, CK showed no significant increase (P>0.05), while isometric peak torque and muscle soreness returned to values similar to baseline after respectively 48 and 72 hours. All muscle damage markers were significantly lower after second compared to first bout. CONCLUSIONS The enhanced eccentric exercise induced symptoms of muscle damage up to 96 hours. However, it provided muscle protection after the second bout, performed four weeks later. Although it was not eccentric-only exercise, the enhancement of eccentric phase provided muscle protection.
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3.
Effect of Muscle-Damaging Eccentric Exercise on Running Kinematics and Economy for Running at Different Intensities.
Satkunskienė, D, Stasiulis, A, Zaičenkovienė, K, Sakalauskaitė, R, Rauktys, D
Journal of strength and conditioning research. 2015;(9):2404-11
Abstract
The objective of this study was to explore the changes in running kinematics and economy during running at different intensities 1 and 24 hours after a muscle-damaging bench-stepping exercise. Healthy, physically active adult women were recruited for this study. The subjects' running kinematics, heart rate, gas exchange, minute ventilation, and perceived exertion were continuously recorded during the increasing-intensity running test on a treadmill for different testing conditions: a control condition and 1 and 24 hours after the bench-stepping exercise test. Two muscle damage markers, muscle soreness and blood creatine kinase (CK) activity, were measured before and 24 hours after the stepping exercise. Muscle soreness and blood CK activity were significantly altered (exact p ≤ 0.05, Monte Carlo test) 24 hours after the bench-stepping exercise. The stride length, stride frequency, and support time at different running intensities did not change. Twenty-four hours after the previous step exercise, ankle dorsiflexion in the support phase was significantly higher during severe-intensity running, the range of knee flexion at the stance phase was significantly lower during moderate-intensity running, and knee flexion at the end of the amortization phase was significantly lower during heavy-intensity running compared with the control values (exact p ≤ 0.05, Monte Carlo test). The running economy at moderate and heavy intensities, maximum ventilation, and maximum heart rate did not change. We conclude that, given moderate soreness in the calf muscles 24 hours after eccentric exercise, the running kinematics are slightly but significantly changed without a detectable effect on running economy.
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4.
The response of cortical alpha activity to pain and neuromuscular changes caused by exercise-induced muscle damage.
Plattner, K, Lambert, MI, Tam, N, Baumeister, J
Scandinavian journal of medicine & science in sports. 2014;(1):166-78
Abstract
Exercise-induced muscle damage (EIMD) is characterized by pain, swelling, and shortening of the muscle; increased serum creatine kinase; decreased force output; and altered neuromuscular function. The aim of this study was to investigate the effects of EIMD to determine the relationship between the peripheral symptoms, neuromuscular changes, and delayed pain sensation during a submaximal movement of the biceps brachii on cortical alpha (α) activity. In contrast to the control (n = 12) group, the experimental (n = 16) group participated in an EIMD protocol, and both groups were monitored for 132 h post-EIMD protocol. At 12 h, neuromuscular functioning was already disturbed while the sensation of pain was perceived, but not fully developed. Muscle pain scores in the experimental group peaked after 36 h with the lowest torque reported at 12 h. α-1 activity increased significantly in the motor and somatosensory area 12 h post-EIMD while α-2 activity increased in the contralateral fronto-central area. At 36 h, pain had further increased and neuromuscular function improved while α-1 and α-2 activities had decreased. We hypothesize that α-1 activity over the motor and somatosensory cortex of the experimental group displays a compensatory increase in response to the changes in neuromuscular function during movement, while an increase in α-2 activity is related to the suppression of pain experienced within the first 12 h.
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Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men.
Burd, NA, Andrews, RJ, West, DW, Little, JP, Cochran, AJ, Hector, AJ, Cashaback, JG, Gibala, MJ, Potvin, JR, Baker, SK, et al
The Journal of physiology. 2012;(2):351-62
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Abstract
We aimed to determine if the time that muscle is under loaded tension during low intensity resistance exercise affects the synthesis of specific muscle protein fractions or phosphorylation of anabolic signalling proteins. Eight men (24 ± 1 years (sem), BMI = 26.5 ± 1.0 kg m(-2)) performed three sets of unilateral knee extension exercise at 30% of one-repetition maximum strength involving concentric and eccentric actions that were 6 s in duration to failure (SLOW) or a work-matched bout that consisted of concentric and eccentric actions that were 1 s in duration (CTL). Participants ingested 20 g of whey protein immediately after exercise and again at 24 h recovery. Needle biopsies (vastus lateralis) were obtained while fasted at rest and after 6, 24 and 30 h post-exercise in the fed-state following a primed, constant infusion of l-[ring-(13)C(6)]phenylalanine. Myofibrillar protein synthetic rate was higher in the SLOW condition versus CTL after 24-30 h recovery (P < 0.001) and correlated to p70S6K phosphorylation (r = 0.42, P = 0.02). Exercise-induced rates of mitochondrial and sarcoplasmic protein synthesis were elevated by 114% and 77%, respectively, above rest at 0-6 h post-exercise only in the SLOW condition (both P < 0.05). Mitochondrial protein synthesis rates were elevated above rest during 24-30 h recovery in the SLOW (175%) and CTL (126%) conditions (both P < 0.05). Lastly, muscle PGC-1α expression was increased at 6 h post-exercise compared to rest with no difference between conditions (main effect for time, P < 0.001). These data show that greater muscle time under tension increased the acute amplitude of mitochondrial and sarcoplasmic protein synthesis and also resulted in a robust, but delayed stimulation of myofibrillar protein synthesis 24-30 h after resistance exercise.
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Effect of amoxicillin/clavulanate on gastrointestinal motility in children.
Gomez, R, Fernandez, S, Aspirot, A, Punati, J, Skaggs, B, Mousa, H, Di Lorenzo, C
Journal of pediatric gastroenterology and nutrition. 2012;(6):780-4
Abstract
AIM: The aim of the present study was to evaluate the effect of amoxicillin/clavulanate (A/C) on gastrointestinal motility. METHODS Twenty consecutive pediatric patients referred for antroduodenal manometry received 20 mg/kg of A/C into the small bowel lumen. In 10 patients (group A), A/C was given 1 hour after and in 10 (group B), 1 hour before ingestion of a meal. Characteristics of the migrating motor complex, including presence, frequency, amplitude, and propagation of duodenal phase III and phase I duration and phase II motility index (MI), were evaluated 30 minutes before and after A/C administration. RESULTS There were no statistically significant differences in age and sex between the 2 groups. Manometry studies were considered normal in 8 patients in each group. In group A, 2 patients developed duodenal phase III after receiving A/C, and no significant difference was found in the MI before and after the drug administration. In group B, 9 patients developed duodenal phase III (P <0.05 vs group A). All phase III occurred within a few minutes from the medication administration. Most duodenal phase III contractions were preceded by an antral component during fasting but never after the medication was administered in either of the 2 groups (P<0.001 vs fasting). In group B, the duration of duodenal phase I was shorter after drug administration (P<0.05). There was no significant difference in duodenal phase II MI before and after A/C administration for the 2 study groups. CONCLUSIONS In children, administration of A/C directly into the small bowel before a meal induces phase III-type contractions in the duodenum, with characteristics similar to those present in the fasting state. These data suggest the possible use of A/C as a prokinetic agent. Further studies are needed to clarify its specific mechanism of action and the group of patients most likely to benefit from its use.
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Determination of muscle activity during running at reduced body weight.
Liebenberg, J, Scharf, J, Forrest, D, Dufek, JS, Masumoto, K, Mercer, JA
Journal of sports sciences. 2011;(2):207-14
Abstract
The aim of this study was to investigate how lower extremity muscles are influenced by body weight support during running at different speeds. Nine participants (age 24 ± 2 years, height 1.75 ± 0.12 m, mass 73.5 ± 15.7 kg) ran at 100%, 115%, and 125% of preferred speed at 100%, 90%, 80%, 70%, and 60% of body weight on a treadmill that provided body weight support. Preferred speed was self-selected by each participant and represented a speed that he or she could sustain if going for a 30 min run. Electromyography (EMG) data were recorded (1000 Hz, 1 min) from the bicep femoris, rectus femoris, tibialis anterior, and gastrocnemius for each condition together with knee angle (electrogoniometer). Average and root mean square EMG were calculated across 30 s. Muscle patterns were determined by smoothing (low-pass filter, 4 Hz) and extracting patterns for 49 cycles defined by consecutive maximum knee flexion angles. Repeated-measures analyses of variance were used to compare average and root mean square across body weight and speeds. Correlations were computed between the 100% speed/100% body weight condition and all other conditions per muscle. There was no interaction between body weight and speed (P > 0.05). Average and root mean square decreased as body weight decreased for all muscles (P < 0.05) and increased across speeds for all muscles (P < 0.05). Correlations for all muscles between conditions were high (range: 0.921-0.999). Although a percent reduction in body weight did not lead to the same reduction in muscle activity, it was clear that reducing body weight leads to a reduction in muscle activity with no changes in muscle activity patterns.
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Less indication of muscle damage in the second than initial electrical muscle stimulation bout consisting of isometric contractions of the knee extensors.
Aldayel, A, Jubeau, M, McGuigan, MR, Nosaka, K
European journal of applied physiology. 2010;(4):709-17
Abstract
This study compared the first and second exercise bouts consisting of electrically evoked isometric contractions for muscle damage profile. Nine healthy men (31 +/- 4 years) had two electrical muscle stimulation (EMS) bouts separated by 2 weeks. The knee extensors of one leg were stimulated by biphasic rectangular pulses (75 Hz, 400 mus, on-off ratio 5-15 s) at the knee joint angle of 100 degrees (0 degrees , full extension) to induce 40 isometric contractions, while the current amplitude was increased to maintain maximal force generation. Maximal voluntary isometric contraction (MVC) torque of the knee extensors at 100 degrees , muscle soreness, pressure pain threshold and plasma creatine kinase (CK) activity were used as indirect markers of muscle damage, and measured before and 1, 24, 48, 72 and 96 h after EMS bout, and the changes over time were compared between bouts. The torque produced during exercise was approximately 30% of MVC, and no significant difference between bouts was evident for the changes in peak and average torque over 40 contractions. MVC decreased significantly (P < 0.05) by 26% immediately and 1 h after both bouts, but the recovery was significantly (P < 0.05) faster after the second bout (100% at 96 h) compared with the first bout (81% at 96 h). Development of muscle soreness and tenderness, and increases in plasma CK activity were significantly (P < 0.05) smaller after the second than the first bout. These results show that changes in muscle damage markers were attenuated in the second EMS bout compared with the initial EMS bout.
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Treatment of periocular wrinkles with topical nifedipine.
Innocenti, M, Ramoni, S, Doria, C, Antropoli, C, Garbagna, N, Grossi, E, Veraldi, S
The Journal of dermatological treatment. 2010;(5):282-5
Abstract
The appearance of facial expression wrinkles is the result of chronic contraction of mimic muscles. Nifedipine is a dihydropyridinic calcium antagonist which blocks muscular cells' calcium channels, therefore inhibiting their contraction. We assumed that topical nifedipine was able to relax mimic muscular fibres in the same way, thus reducing the depth of wrinkles. We performed a clinical and experimental study, enrolling 64 female patients with periocular wrinkles. They applied a cream containing 0.5% nifedipine (Antrox; Bracco, Milan, Italy) once daily for 90 days. The length and depth of wrinkles (measured by a digital profilometer), moisturizing of periocular skin (measured by a corneometer), and trans-epidermal water loss (TEWL; measured by a tewameter), were evaluated. All parameters were measured before the beginning of treatment, and 45 and 90 days later. At the end of the study, topical nifedipine proved statistically effective in reducing the depth of wrinkles. No significant differences in the length of wrinkles were recorded. No significant changes were observed in moisturizing. TEWL gradually improved, although without statistical significance. On the basis of the results of this study, 0.5% nifedipine cream seems to be effective in reducing the depth of periocular wrinkles. Other studies are necessary in order to confirm these results.
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10.
Beta-alanine and the hormonal response to exercise.
Hoffman, J, Ratamess, NA, Ross, R, Kang, J, Magrelli, J, Neese, K, Faigenbaum, AD, Wise, JA
International journal of sports medicine. 2008;(12):952-8
Abstract
The effect of 30 days of beta-alanine supplementation (4.8 g per day) on resistance exercise performance and endocrine changes was examined in eight experienced resistance-trained men. An acute resistance exercise protocol consisting of 6 sets of 12 repetitions of the squat exercise at 70 % of one-repetition maximum (1-RM) with 1.5 minutes of rest between sets was performed before and after each supplemental period. Blood draws occurred at baseline (BL), immediate (IP), 15-minutes (15P) and 30-minutes (30P) postexercise for growth hormone, testosterone and cortisol concentrations. A 22 % (p < 0.05) difference in total number of repetitions performed at the end of 4 weeks of supplementation was seen between beta-alanine (BA) and placebo (PL), and Delta mean power was greater in BA (98.4 +/- 43.8 w) vs. PL (7.2 +/- 29.6 w). Growth hormone concentrations were elevated from BL at IP and 15P for both groups, while cortisol concentrations were greater than BL at all time points for both BA and PL. No group differences were noted. No change from BL was seen in testosterone concentrations for either group. Results indicate that four weeks of beta-alanine supplementation can significantly improve muscular endurance during resistance training in experienced resistance-trained athletes. However, these performance gains did not affect the acute endocrine response to the exercise stimulus.