Effect of a Carbohydrate-Electrolyte Solution on Fluid Balance and Performance at a Thermoneutral Environment in International-Level Fencers

© 2019 by the National Strength & Conditioning Association.Chryssanthopoulos, C, Tsolakis, C, Bottoms, L, Toubekis, A, Zacharogiannis, E, Pafili, Z, and Maridaki, M. Effect of a carbohydrate-electrolyte solution on fluid balance and performance at a thermoneutral environment in international-level fencers. J Strength Cond Res 34(1): 152-161, 2020-The purpose of the study was to examine a possible effect of a carbohydrate-electrolyte (CHO-E) solution on fluid balance and performance in fencing at a thermoneutral environment. Sixteen fencers performed two 120-minute training sessions separated by 7-14 days under similar environmental conditions (temperature: 20.3° C and humidity: 45-47%). Each session consisted of 60-minute conditioning exercises followed by 10 bouts of 3 minutes against the same opponent with 3-minute interval between each bout. Participants ingested at regular intervals either a 6% CHO-E solution or an artificially sweetened water (PL) in a counterbalanced order. No difference was observed between conditions in the heart rate responses, perceived exertion, changes in plasma volume, urine specific gravity, number of bouts won or lost, or points for and against. Considerable variability was observed in body mass changes that revealed significant differences at the time level (i.e., pre- vs. post-exercise) (F1,15 = 9.31, p = 0.008, η = 0.38), whereas no difference was found between conditions (i.e., CHO-E vs. PL) (F1,15 = 0.43, p = 0.52, η = 0.03) and conditions × time interaction (F1,15 = 3.57, p = 0.078, η = 0.19). Fluid loss was not significantly different between conditions (p = 0.08, d = 0.47). The blood glucose level was higher (p < 0.01) after exercise in CHO-E, whereas the blood lactate level was similar between conditions. In conclusion, the CHO-E solution was as effective as the artificially sweetened water in terms of fluid balance and fencing performance at a thermoneutral environment. Because of large individual variability, fencers should monitor their fluid intake and body fluid loss in training and competition.Peer reviewedFinal Accepted Versio

Systemic Redox Imbalance in Chronic Kidney Disease: A Systematic Review.

Patients with chronic kidney disease (CKD) experience imbalance between oxygen reactive species (ROS) production and antioxidant defenses leading to cell and tissue damage. However, it remains unclear at which stage of renal insufficiency the redox imbalance becomes more profound. The aim of this systematic review was to provide an update on recent advances in our understanding of how the redox status changes in the progression of renal disease from predialysis stages 1 to 4 to end stage 5 and whether the various treatments and dialysis modalities influence the redox balance. A systematic review was conducted searching PubMed and Scopus by using the Cochrane and PRISMA guidelines. In total, thirty-nine studies met the inclusion criteria and were reviewed. Even from an early stage, imbalance in redox status is evident and as the kidney function worsens it becomes more profound. Hemodialysis therapy per se seems to negatively influence the redox status by the elevation of lipid peroxidation markers, protein carbonylation, and impairing erythrocyte antioxidant defense. However, other dialysis modalities do not so far appear to confer advantages. Supplementation with antioxidants might assist and should be considered as an early intervention to halt premature atherogenesis development at an early stage of CKD

Pre-Exercise Maltodextrin Ingestion and Transient Hypoglycemia in Cycling and Running

International Journal of Exercise Science 13(2): 1691-1704, 2020. This study examined the phenomenon of transient hypoglycemia and metabolic responses to pre-exercise carbohydrate (CHO) maltodextrin ingestion in cycling and running on the same individuals. Eleven active males cycled or ran for 30 min at 80% maximal heart rate (HRmax) after ingestion of either 1g/kg body mass maltodextrin (CHO-Cycle and CHO-Run respectively) or placebo (PL-Cycle and PL-Run) solutions. Fluids were ingested 30min before exercise in a double-blind and random manner.Blood glucose and serum insulin were higher before exercise in CHO (mean CHO-Cycle+CHO-Run) (Glucose: 7.4 ± 0.3 mmol.l-1; Insulin: 59 ± 10 mU.l-1) compared to placebo (mean PL-Cycle+PL-Run) (Glucose: 4.7 ± 0.1 mmol.l-1; Insulin: 8 ± 1 mU.l-1) (p\u3c0.01), but no differences were observed during exercise among the 4 conditions. Mean blood glucose did not drop below 4.1 mmol.l-1 in any trial. However, six volunteers in CHO-Cycle and seven in CHO-Run experienced blood glucose concentration \u3c 3.5 mmol.l-1 at 20min of exercise and similar degree of transient hypoglycemia in both exercise modes. No association was found between insulin response to maltodextrin ingestion and drop in blood glucose during exercise. Blood lactate increased with exercise more in cycling compared to running, and plasma free fatty acids (FFA) concentrations were higher in placebo compared to CHO irrespective of exercise mode (p\u3c0.01). The ingestion of maltodextrin 30min before exercise at about 80% HRmax produced similar glucose and insulin responses in cycling and running in active males. Lactate was higher in cycling, whereas maltodextrin reduced FFA concentrations independently of exercise mode

Phosphorus nutritional knowledge among dialysis health care providers and patients: a multicenter observational study

Background-aims Phosphorus nutritional knowledge level of hemodialysis patients and renal nurses has been found to be low, while respective knowledge of nephrologists has not been studied yet. There are equivocal results regarding the association of phosphorus nutritional knowledge level and serum phosphorus values. The aim of this study was to assess phosphorus nutritional knowledge of hemodialysis patients, nephrologists and renal nurses and seek potential interventions to improve patients’ adherence to phosphorus and overall nutritional guidelines. Methods This cross-sectional observational study was conducted on sixty eight hemodialysis patients, 19 renal nurses and 11 nephrologists who were recruited from 3 hemodialysis units in Greece. Phosphorus nutritional knowledge of the participants was assessed by a 25-item item questionnaire (CKDKAT–N) which included 15 questions on phosphorus and 10 questions on protein, sodium, and potassium knowledge. Results Nephrologists had higher CKDKAT–N total (19.1 ± 3.6 vs 14.1 ± 2.8 and 13.2 ± 2.8, P < 0.01) and phosphorus knowledge scores (10.6 ± 2.7 vs 7.6 ± 2.2 and 7.3 ± 2.0, P < 0.01) compared to renal nurses and patients respectively. There were no differences in total and phosphorus knowledge scores between nurses and patients. Patients and nurses answered correctly significantly less questions regarding phosphorus compared with the rest of the questions (P < 0.01) while no such difference was found in nephrologists. Serum phosphorus was positively correlated with phosphorus knowledge score (r = 0.31, P = 0.02), and negatively correlated with patient age (r = −0.34, P < 0.05). None of the patients, 11% of the nurses and 27% of the nephrologists answered correctly all three questions regarding P, K and Na dietary recommendations (P < 0.01). Conclusions The study confirms that hemodialysis patients have low renal nutrition knowledge while higher nutritional phosphorus knowledge does not lead to lower serum phosphorus values. Alarmingly, renal nurses have been found to have a similar level of knowledge with hemodialysis patients, something that needs to be taken into account when training the new dialysis staff. Nephrologists have superior knowledge; however they are still lacking essential nutritional knowledge that could affect patients' and nurses’ overall understanding. Continuing education on nutrition of nephrologists and renal nurses could improve nutrition care of hemodialysis patients

Changes in the angle-force curve of human elbow flexors following eccentric and isometric exercise.

The aim of this study was to explore and compare the magnitude and time-course of the shift in the angle-force curves obtained from maximal voluntary contractions of the elbow flexors, both before and 4 consecutive days after eccentric and isometric exercise. The maximal isometric force of the elbow flexors of fourteen young male volunteers was measured at five different elbow angles between 50 degrees and 160 degrees . Subjects were then divided into two groups: the eccentric group (ECC, n=7) and the isometric group (ISO, n=7). Subjects in the ECC group performed 50 maximal voluntary eccentric contractions of the elbow flexors on an isokinetic dynamometer (30 degrees x s(-1)), while subjects in the ISO group performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position. Following the ECC and ISO exercise protocols, maximal isometric force at the five angles, muscle soreness, and the relaxed (RANG) and flexed (FANG) elbow angles were measured at 24 h intervals for 4 days. All results were presented as the mean and standard error, and a quadratic curve was used to model the maximal isometric force data obtained at the five elbow angles. This approach not only allowed us to mathematically describe the angle-force curves and estimate the peak force and optimum angle for peak force generation, but also enabled us to statistically compare the shift of the angle-force curves between and within groups. A large and persistent shift of the angle-force curve towards longer muscle lengths was observed 1 day after eccentric exercise ( P<0.01). This resulted in a approximately 16 degrees shift of the optimum angle for force generation, which remained unchanged for the whole observation period. A smaller but also persistent shift of the angle-force curve was seen after isometric exercise at long muscle length ( P<0.05; shift in optimum angle approximately 5 degrees ). ECC exercise caused more muscle damage than ISO exercise, as indicated by the greater changes in RANG and ratings of muscle soreness ( P<0.05). It was suggested that the shift in the angle-force curve was proportional to the degree of muscle damage and may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle

Effects of Training Surface on Physiological Characteristics of Prepubescent Female Volleyball Players

Purpose: The present study investigated the effects of different training surfaces on physiological characteristics of prepubescent female volleyball players. Method: 45 prepubescent girls (age: 11.1 ± 0.5 years) were separated in groups S (N=15) and H (N=15) that consisted of volleyball players, while group C (N=15) consisted of girls that had no volleyball training experience. Groups S and H participated in a 10-week volleyball training program including sprints, jumps and technical exercises, while group C executed only technical skills exercises. Group S trained on sand surface, while groups H and C trained on hard surface indoors. Aerobic capacity (20m shuttle run), agility (Illinois test), countermovement (CMJ) and squat jump (SJ) as well as 10m sprint test were conducted before, in the middle (5th week) and after the end of the training program for groups S and H. Group C was tested only before and after the training period. Results: Aerobic capacity, agility, jumping and sprinting ability were significantly (p&lt;0.01) improved in groups S and H even from the 5th week of training. Group S achieved greater improvements than group H in all tested variables. Conclusion: Training on sand surface seems to promote training adaptations improving the physiological characteristics of prepubescent female volleyball players

Effect of Training Surface on Agility and Passing Skills of Prepubescent Female Volleyball Players

The purpose of the present study was to investigate the effect of different training surfaces (hard or sand surface) on agility and passing skills of prepubescent female volleyball players. 45 prepubescent girls (age: 11.1 ± 0.5 years) participated in this study and were separated in three groups. Groups S (N=15) and I (N=15) consisted of volleyball players, while group C (N=15) consisted of girls that had no volleyball training experience. All groups participated in a 10-week (3 days/week) volleyball training program that included technical and passing skills exercises. The program of groups S and I also included jumping and sprinting exercises. The training program of group S was conducted on sand surface, while groups I and C trained on hard surface. Measurements of agility (T-test and 505-test) and passing skills were conducted on both hard and sand surface before, in the middle (5th week) and after the end of the training program for groups S and I. Group C was tested only on hard surface before and after the training period. Data were analyzed using two-way ANOVA for independent samples. Agility T-test and 505-test were significantly (p&lt;0.001) improved in all three groups after the 10-week training program. Agility improvement of group S was significantly (p&lt;0.001) greater than the other two groups (I and C), regardless of the surface (hard or sand) that the test was executed. Group S achieved greater improvements than the other two groups in passing skills too. All three groups were significantly (p&lt;0.001) improved in overhead and forearm passing accuracy after the 10-week training period, but it was group S that achieved the greatest improvement, regardless of the (hard or sand) that the test was executed. In conclusion training on sand surface could be a useful and effective tool for improving agility and passing skills in prepubescent female volleyball player

CARDIORESPIRATORY CHARACTERISTICS AND CHOLESTEROL RESPONSES TO A SINGLE SESSION OF HEAVY LEG PRESS EXERCISE

The effect of resistance exercise on blood lipids is not clear yet. The purpose of this study was to examine the cholesterol responses to a heavy resistance leg press exercise emphasizing on the eccentric movement 24 and 48 hours following exercise and to quantify the cardiorespiratory responses of the exercise bout in an attempt to clarify the exercise characteristics that may be responsible for the effects of heavy resistance exercise on blood lipids. Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yrs (76.2 ± 2.5 kg, 1.79 ± 0.02 m) performed a session of heavy RE emphasizing on the eccentric movement consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. Venous blood samples were obtained at rest (control) and 24 and 48 hours following exercise. Average VO2 at rest was 4.0 ± 0.4 ml·min-1·kg-1, during exercise 19.6 ± 0.2 ml·min-1·kg-1 and during the 180 sec recovery period between sets 12.5 ± 0.2 ml·min-1·kg-1. RER values decreased with the progression of the exercise and were significantly lower during the last four sets compared with the first four sets of the exercise session. Resting heart rate was 67 ± 2 bpm, and maximum heart rate during exercise was 168 ± 1 bpm. Serum creatine kinase was significantly elevated on day 1 (1090 ± 272 U·L-1, p < 0.03) and peaked on day 2 (1230 ± 440 U·L-1 p < 0. 01). Total cholesterol, HDL cholesterol and calculated LDL cholesterol concentration did not change significantly following with exercise. This protocol of heavy resistance exercise has no effect on TC or cholesterol sub-fraction concentration 24 and 48 hours following exercise which may be due to the low energy expenditure of the exercise and/or to the gender of the participant

Growth and Vascular Remodeling Factors during a Basketball Season in Adolescent Boys

Background: Circulating factors during exercise training are implicated in the adaptive mechanisms of physical conditioning. However, there is lack of information regarding the effect of basketball training on circulating growth and vascular remodeling factors in adolescents. The purpose of this study was to characterize the serum insulin-like growth factor 1 (IGF-1), vascular endothelial growth factor (VEGF), matrix metalloproteinase 3 (MMP-3), albumin (ALB) and aldolase (ALD) responses in healthy adolescent boys over the course of a regular basketball season, and compared them with age- and sex-matched participants not involved systematically in any physical activity.Materials and methods: We evaluated systemic and body composition changes in basketball athletes (n=34; mean age 17.1±0.7 yrs) and controls (n=21; mean age 17.2±0.9 yrs) before training, at peak season (8 wks), and at the end of the season (32 wks).Results: Changes in % body fat and body mass index (BMI) were observed in the training group (TG) over time (P&lt;0.05-0.001), while these parameters remained unchanged in the control group (CG). TG exhibited higher serum ALB and ALD levels compared with CG (P&lt;0.001) while they did not change over time (P&gt;0.05). Circulating IGF-1, VEGF and MMP-3 levels increased in TG over time (P&lt;0.01) and were higher compared to CG (P&lt;0.001), in which there were not any changes.</p