The objective of this study was to determine whether creatine supplementation (CrS) could improve mechanical power output, and swimming performance in highly trained junior competitive fin swimmers. Sixteen male fin swimmers (age:15.9±1.6... more
The objective of this study was to determine whether creatine supplementation (CrS) could improve mechanical power output, and swimming performance in highly trained junior competitive fin swimmers. Sixteen male fin swimmers (age:15.9±1.6 years) were randomly and evenly assigned to either a creatine (CR, 4×5 g/day creatine monohydrate for 5 days) or placebo group (P, same dose of a dextrose-ascorbic acid placebo) in a double-blind research. Before and after CrS the average power output was determined by a Bosco-test and the swimming time was measured in two maximal 100 m fin swims. After five days of CrS the average power of one minute continuous rebound jumps increased by 20.2%. The lactate concentration was significantly less after 5 minutes restitution at the second measurement in both groups. The swimming time was significantly reduced in both first (pre: 50.69±1.41 s; post: 48.86±1.34 s) and second (pre: 50.39±1.38 s; post: 48.53±1.35 s) sessions of swimming in CR group, but remained almost unchanged in the P group. The results of this study indicate that five day Cr supplementation enhances the dynamic strength and may increase anaerobic metabolism in the lower extremity muscles, and improves performance in consecutive maximal swims in highly trained adolescent fin swimmers. Keywords: mechanical power, lower extremity muscles, swimming performance, ergogenic aid, creatine
Low capacity runner (LCR) rats have been developed by divergent artificial selection for treadmill endurance capacity to explore an aerobic biology-disease connection. The beneficial effects of resveratrol supplementation have been... more
Low capacity runner (LCR) rats have been developed by divergent artificial selection for treadmill endurance capacity to explore an aerobic biology-disease connection. The beneficial effects of resveratrol supplementation have been demonstrated in endurance running. In this study it was examined whether 12 weeks of treadmill exercise training and/or resveratrol can retrieve the low running performance of the LCR and impact mito- chondrial biogenesis and quality control. Resveratrol regressed running performance in trained LCR (p<0.05). Surprisingly, exercise and resveratrol treatments significantly decreased pAMPK/AMPK, SIRT1, SIRT4, forkhead transcription factor 1 (FOXO1) and mitochondrial transcription factor A (TFAM) levels in these animals (p<0.05). Mitochondrial fusion protein, HSP78 and polynucleotide phosphorylase were significant- ly induced in LCR-trained, LCR-resveratrol treated, LCR-trained and resveratol treated groups compared to LCR-controls. The data indicate that the AMPK-SIRT1-NAMPT- FOXO1 axis could be important to the limited aerobic endurance capacity of low running capacity rats. Resveratrol supplementation was not beneficial in terms of aerobic endurance performance, mitochondrial biogenesis, or quality control.
High Capacity Runner (HCR) rats have been developed by divergent artificial selection for treadmill endurance running capacity to explore an aerobic biology-disease connection. The beneficial effects of resveratrol supplementation have... more
High Capacity Runner (HCR) rats have been developed by divergent artificial selection for treadmill endurance running capacity to explore an aerobic biology-disease connection. The beneficial effects of resveratrol supplementation have been demonstrated in endurance running and the antioxidant capacity of resveratrol is also demonstrated. In this study we examine whether 12 weeks of treadmill exercise training and/or resveratrol can enhance performance in HCR. Indeed, resveratrol increased aerobic per- formance and strength of upper limbs of these rats. Moreover, we have found that resveratrol activated the AMP-activated protein kinase, SIRT1, and mitochondrial transcription factor A (p < 0.05). The changes in mitochondrial fission/fusion and Lon protease/HSP78 levels suggest that exercise training does not sig- nificantly induce damage of proteins. Moreover, neither exercise training nor resveratrol supplementa- tion altered the content of protein carbonyls. Changes in the levels of forkhead transcription factor 1 and SIRT4 could suggest increased fat utilization and improved insulin sensitivity. These data indicate, that resveratrol supplementation enhances aerobic performance due to the activation of the AMPK- SIRT1-PGC-1a pathway.
In the present study we investigated kinematical characteristics of the knee and ankle extensors to esti- mate the length change properties of the contractile and the passive elements in countermovement jumps (CMJ) and drop jumps (DJ)... more
In the present study we investigated kinematical characteristics of the knee and ankle extensors to esti- mate the length change properties of the contractile and the passive elements in countermovement jumps (CMJ) and drop jumps (DJ) performed with small (40°) and large (80°) range of joint motion (SRM and LRM). At SRM the accelerations at maximal muscle lengths compared with the last phase of joint flexion were greater for the gastrocnemius and the soleus (124.9% and 79.4%) and also were greater than at the beginning of joint extension, while no difference was measured at LRM. The differences sug- gest that at LRM the length change of the serial passive elements from the end of joint flexion to the beginning of joint extension is minimal and simultaneously the length change of the contractile elements is significant, but at SRM – especially in the plantar flexors – the length change of the contractile elements is minimal while in the passive elements significant. It can be presumed that for SRM at the end of joint flexion significant elastic energy is stored and at the beginning of joint extension reused, while for LRM elastic energy storage is not dominant.
Recent evidence has suggested that relationship between approach speed and distance jumped may not be linear. The aims of this study were (1) to test the hypothesis that using a short approach... more
Recent evidence has suggested that relationship between approach speed and distance jumped may not be linear. The aims of this study were (1) to test the hypothesis that using a short approach (6-8-10-12 strides) of increasing length, performance variables will be non-linearly related to distance jumped, (2) to investigate the nature of these relationships for a group of long jumpers and individuals within the group, and (3) to use the regression analysis to determine the optimum number of run-up strides and predict the jumping distance that would be achieved with an optimum length run-up for an individual jumper. Eight male long jumpers with different skill levels (body mass: 75.2±2.2 kg and body height: 188.0±4.2 cm) performed a series of short-approach maximal jumps and the full-length approach in a competition. Kinematic data were collected from video analysis. The relationship between the number of approach strides and velocity, and distance jumped were shown to be best represented by second order polynomial equations. When applied on an individual basis, the predicted jump distances (6.95±.61 m) agreed very well with those found in actual competition (6.96±.58m). As a result, these individual relationships were used to comment on individual optimal approach lengths and to evaluate an individual’s potential for performance in the long jump event. It was concluded that the short approach model of performance is a valuable paradigm for investigating long jump behaviour and the performance potential of individuals. The findings also supported the simplified mathematical model proposed in the literature for the study of long jump performance.
Aging results in significant loss of mass and function of the skeletal muscle, which negatively impacts the quality of life. In this study we investigated whether aerobic exercise training has the potential to alter anabolic and catabolic... more
Aging results in significant loss of mass and function of the skeletal muscle, which negatively impacts the quality of life. In this study we investigated whether aerobic exercise training has the potential to alter anabolic and catabolic pathways in the skeletalmuscle. Five and twenty eightmonth old ratswere used in the study. Aging resulted in decreased levels of follistatin/mTOR/Akt/Erk activation and increased myostatin/Murf1/2, proteasome subunits, and protein ubiquitination levels. In addition, TNF-α, reactive oxygen species (ROS), p53, and Bax levels were increased while Bcl-2 levelswere decreased in the skeletal muscle of aged rats. Six weeks of exercise training at 60% of VO2max reversed the age-associated activation of catabolic and apoptotic pathways and increased anabolic signaling. The results suggest that the age-associated loss of muscle mass and cachexia could be due to the orchestrated down-regulation of anabolic and up-regulation of catabolic and pro-apoptotic processes. These metabolic changes can be attenuated by exercise training.
