Publications by authors named "Georgios Ermidis"

15 Publications

  • Page 1 of 1

Physical performance and loading for six playing positions in elite female football: full-game, end-game, and peak periods.

Scand J Med Sci Sports 2021 Mar 22. Epub 2021 Mar 22.

Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark.

The present study investigated the position-specific match demands and heart rate response of female elite footballers, with special focus on the full-game, end-game, and peak-intensity periods. In total, 217 match observations were performed in 94 players from all eight teams of the best Danish Women's League, that is, goalkeepers (GK, n = 10), central defenders (CD, n = 23), full-backs (FB, n = 18), central midfielders (CM, n = 28), external midfielders (EM, n = 18), and forwards (FW, n = 11). Positional data (GPS; 10 Hz Polar Team Pro) and HR responses were collected. HR and HR were 87%-89% and 98%-99% of HR , for outfield players, with no positional differences. CM, EM, and FB covered 8%-14% greater (P < .001) match distances than CD. EM, FW, FB, and CM performed 40%-64% more (P < .05) high-speed running and 41%-95% more (P < .01) very-high-speed running (VHSR) than CD. From the first to the last 15-minute period, total distance, except for FW, number of VHSR, except FB, peak speed and sum of accelerations and sum of decelerations decreased (P < .05) for all outfield positions. In the most intense 5-minute period, EM, FB, and CM performed 25%-34% more (P < .01) HSR than CD, whereas EM, FW, and FB performed 36%-49% more (P < .01) VHSR than CD. In conclusion, competitive elite female matches impose high physical demands on all outfield playing positions, with high aerobic loading throughout matches and marked declines in high-speed running and intense accelerations and decelerations toward the end of games. Overall physical match demands are much lower for central defenders than for the other outfield playing positions, albeit this difference is minimized in peak-intensity periods.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/sms.13877DOI Listing
March 2021

Fitness and Performance Testing of Male and Female Beach Soccer Players-A Preliminary Investigation.

Front Sports Act Living 2021 23;3:636308. Epub 2021 Feb 23.

Faculty of Health Sciences and Sports, Universidade Europeia, Lisbon, Portugal.

This study aimed to compare performance on sand and a firm surface and to describe the physical capacity of male and female beach soccer players. Sixty-six male and 29 female competitive beach soccer players voluntarily participated in this study. Firstly, within-subjects test scores were compared to scores on a firm surface (criterion validity; = 15 men) and reconducted on a second occasion (reliability; = 51 men). Secondly, the best score on sand was retained to compare test performance between ages (classified as below 20, 20-30, and above 30 years) and sexes. Performance assessments included sprint time over 5 and 15 m (once on a firm surface and twice on sand), standing long jump (SLJ, once on a firm surface and twice on sand) and Yo-Yo intermittent recovery level 1 (Yo-Yo IR1, once on a firm surface and once on sand; only data for men were available). Five-m sprint and Yo-Yo IR1 performance on sand were not correlated to performance on a firm surface ( > 0.05). Test-retest reliability was acceptable for the 15-m sprint and SLJ tests (ICC > 0.90; CV < 5%). Performance in 15-m sprint and maximal sprinting speed were moderately lower in male players aged above 30 years. compared to players aged below 30 years ( = 0.35-0.42; < 0.05). Irrespective of the age group, weight-bearing power-based performance mass was moderately to very largely higher in male players than in female players ( = 0.42-0.88; < 0.05). The lack of a consistent relationship between performance on sand and on a firm surface might indicate the need to develop specific test batteries for sand-based athletes. Age-related differences in physical performance were evident only in sprint capacity. Further studies are warranted to elucidate our preliminary findings and to develop the sand specific tests.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fspor.2021.636308DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7940533PMC
February 2021

Can psychological characteristics, football experience, and player status predict state anxiety before important matches in Danish elite-level female football players?

Scand J Med Sci Sports 2020 Nov 17. Epub 2020 Nov 17.

Sports Science Department, Halmstad University, Halmstad, Sweden.

Elite football can make players feel nervous, and personality characteristics, as well as experience, affect how well pressure is handled before important games. Studying the psychological characteristics of female football players can provide information on how well psychological pressure is handled and generate knowledge on how to support players in order to improve performance. Based on a sample of 128 female elite football players from 8 top-level teams, the present study investigates whether psychological characteristics and football experience/player stus in elite female football players can predict state anxiety before important matches. Our results outline that high age and national team experience negatively predicted most of the trait anxiety subscales. In line with previous research, no psychological differences were found between goalkeepers, defenders, midfielders, and strikers while starting players revealed to have significantly lower trait anxiety. When measuring before important matches, we found that somatic state anxiety was negatively associated with senior national team experience and positively associated with worry trait anxiety and fear of failure. Cognitive state anxiety was negatively associated with hope for success and positively associated with somatic and worry trait anxiety. Self-confidence was positively associated with youth national team experience and negatively associated with worry trait anxiety. It can be concluded that psychological characteristics and national team experience are both important for optimal state anxiety before important matches in elite-level women's football. Implications for practice and future research are discussed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/sms.13881DOI Listing
November 2020

Anthropometric and fitness associations in U17 Italian football players.

J Sports Med Phys Fitness 2020 Sep;60(9):1254-1260

Portugal Football School, Portuguese Football Federation, Oeiras, Portugal -

Background: The purpose of this study was to determine possible relationships between anthropometric characteristics and functional capacities in young football (soccer) players.

Methods: Anthropometric characteristics, estimated peak height velocity (PHV), muscular endurance (sit-up), lower-limb power (countermovement jump, CMJ), sprint time over 5 and 15 m (T5 and T15), agility (Arrowhead agility test), repeated sprint ability (RSA), intermittent recovery capacity (Yo-Yo intermittent recovery test, Yo-Yo IR1) and technical skills (short dribbling tests) were assessed in a group of U17 players (N.=47) competing at regional level. Magnitude-based inferences were used for analyses.

Results: Players with later PHV had greater muscle endurance (r [90% CIs] =0.41 [0.18; 0.59]) and CMJ (r=0.47 [0.25; 0.64]). Body mass, height and percentage of fat mass were positively associated to T5 and T15 (r=0.24-0.47). CMJ was moderately associated with agility, T5, T15 and Yo-Yo IR1 performance (r=-0.42 [-0.60; -0.19], -0.57 [-0.71; -0.38], 0.35[0.11; 0.54], respectively). Quickest players over 15 m were also the most agile and the most capable to perform intermittent recovery exercise (r=0.30-0.36). No significant correlations were found for RSA and other variables.

Conclusions: Body size is likely detrimental for power-related capacities (tallest and heaviest players reported the lowest sprint performance). Notwithstanding, sprint and jump were related to greater intermittent recovery performance. However, caution should be taken when generalizing our findings, given our reduced sample size. In addition, our observed correlations were of small-to-moderate magnitude, and therefore, future research should explore further determinants of functional capacities in these age-group players.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.23736/S0022-4707.20.10963-0DOI Listing
September 2020

On-Ice and Off-Ice Fitness Profiles of Elite and U20 Male Ice Hockey Players of Two Different National Standards.

J Strength Cond Res 2020 Dec;34(12):3369-3376

Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark.

Vigh-Larsen, JF, Haverinen, MT, Panduro, J, Ermidis, G, Andersen, TB, Overgaard, K, Krustrup, P, Parkkari, J, Avela, J, Kyröläinen, H, and Mohr, M. On-ice and off-ice fitness profiles of elite and U20 male ice hockey players of two different national standards. J Strength Cond Res 34(12): 3369-3376, 2020-Differences in body composition and performance were investigated between elite and U20 male ice hockey players of 2 different national standards. One hundred seventy-nine players were recruited from the highest Finnish (n = 82) and Danish (n = 61) national level, as well as from 1 U20 team from Finland (n = 19) and Denmark (n = 17). Body composition and countermovement jump performance (CMJ) were measured off-ice in addition to on-ice assessments of agility, 10- and 30-m sprint performance, and endurance capacity (the maximal Yo-Yo Intermittent Recovery Level 1 Ice Hockey Test, Yo-Yo IR1-IHmax). Large differences in on-ice performances were demonstrated between Finnish and Danish elite players for agility, 10- and 30-m sprint performance (2-3%, P ≤ 0.05), and Yo-Yo IR1-IHmax performance (15%, P ≤ 0.05). By contrast, no differences (P > 0.05) were present between elite players for CMJ ability or body composition. However, elite players possessed more body and muscle mass than U20 players. Finally, the Finnish U20 cohort had a similar performance level as the Danish elite players and superior 10-m sprint performance, whereas the Danish U20 level was inferior to the other groups in every performance assessment (P ≤ 0.05). In conclusion, on-ice speed and endurance differ markedly between elite players of 2 different national standards with no distinction in body composition or CMJ ability. Moreover, the most consistent difference between U20 and senior elite players was related to body and muscle mass. These results highlight the usefulness of on-ice assessments and suggest the importance of on-ice high-intensity training in elite players in addition to training targeted the development of lean body mass in youth prospects.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1519/JSC.0000000000003836DOI Listing
December 2020

Anthropometric and Functional Profile of Selected vs. Non-Selected 13-to-17-Year-Old Soccer Players.

Sports (Basel) 2020 Aug 9;8(8). Epub 2020 Aug 9.

School of Exercise and Sport Science, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37131 Verona, Italy.

The purpose of this study was to compare anthropometric and functional profiles of 13-to-17-year-old soccer players according to their competitive level. Height, body mass, percentage of body fat, countermovement jump height, change of direction ability, 5- and 15-m sprint times, repeated sprint ability (RSA), intermittent recovery performance, and dribbling skills were collected in 115 young Italian soccer players. Players were divided into selected (i.e., competing at national level, n = 17 U15 and 47 U17) and non-selected (i.e., competing at regional level, n = 43 U15 and 8 U17) groups. U17 selected players were taller, quicker over 5 and 15 m, more agile, and had better RSA, prolonged intermittent recovery ability, and dribbling skills than their non-selected counterparts ( = 0.28-0.55, < 0.05). In particular, selected players showed lower times on the first three and the last shuttle of the RSA test ( = 0.28-0.34, < 0.05). No significant differences were observed in U15 players ( > 0.05). Discriminant analysis revealed that dribbling skills, 15-m sprint time, and height best discriminate U17 players by competitive level ( < 0.001). Anthropometric characteristics and functional abilities can discriminate across competitive standards between male U17 but not U15 soccer players. In particular, these findings suggest the importance of dribbling skills, 15-m sprint, and height in U17 players.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/sports8080111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466633PMC
August 2020

Adapted recreational football small-sided games improve cardiac capacity, body composition and muscular fitness in patients with type 2 diabetes.

J Sports Med Phys Fitness 2020 Sep 12;60(9):1261-1268. Epub 2020 Jun 12.

Department of Human Movement Sciences and Wellbeing, Parthenope University, Naples, Italy -

Background: The usefulness of adapted small-sided games (SSGs) in improving cardiac function in subjects with T2DM is still debated. Here we evaluated the effects of 18 weeks indoor muscular activation training (6 weeks; IMA) followed by adapted SSGs football training (12 weeks) on cardiac function, muscular fitness, body composition and adiponectin expression in sedentary T2DM volunteers.

Methods: Six T2DM patients underwent IMA protocol of 6 weeks, twice a week followed by 12 weeks SSGs (5-a-side, once a week) training. Glucose, lipid profile and serum homocysteine concentration, body composition (BC), bone mineral density (DEXA), were determined at baseline and after 18 weeks (IMA+SSGs). VO2max and muscular fitness were recorded at baseline and after IMA (6 weeks) and SSGs (12 weeks), respectively.

Results: No significant differences were found for VO2max and muscular fitness after 6weeks of IMA. After 18 weeks (6 weeks IMA + 12 weeks SSGs) of training, significant improvements were found in the following parameters: work capacity, VO2peak, Ventilation (VEpeak), breathing reserve consumption and oxygen uptake efficiency slope (P<0.05); leg fitness (P<0.05), BC (P<0.05), vertebral column T-score (P<0.01) and adiponectin (total and high-molecular-weight; P<0.05). Compared to baseline, a reduction in serum homocysteine occurred after 18 weeks of training (P<0.05).

Conclusions: We evidenced that weekly adapted SSGs friendly football matches for 12 weeks improve cardiorespiratory capacity and the expression of independent markers associated with cardiovascular risk in T2DM patients, suggesting an overall reduced CVD-risk in these patients. These preliminary data encourage us to test the efficacy of this type of exercise in a larger population.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.23736/S0022-4707.20.10498-5DOI Listing
September 2020

Muscle Metabolism and Fatigue during Simulated Ice Hockey Match-Play in Elite Players.

Med Sci Sports Exerc 2020 10;52(10):2162-2171

Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Copenhagen, DENMARK.

Purpose: The present study investigated muscle metabolism and fatigue during simulated elite male ice hockey match-play.

Methods: Thirty U20 male national team players completed an experimental game comprising three periods of 8 × 1-min shifts separated by 2-min recovery intervals. Two vastus lateralis biopsies were obtained either during the game (n = 7) or pregame and postgame (n = 6). Venous blood samples were drawn pregame and at the end of the first and last periods (n = 14). Activity pattern and physiological responses were continuously monitored using local positioning system and heart rate recordings. Further, repeated-sprint ability was tested pregame and after each period.

Results: Total distance covered was 5980 ± 199 m with almost half the distance covered at high skating speeds (>17 km·h). Average and peak on-ice heart rate was 84% ± 2% and 97% ± 2% of maximum heart rate, respectively. Muscle lactate increased (P ≤ 0.05) more than fivefold and threefold, whereas muscle pH decreased (P ≤ 0.05) from 7.31 ± 0.04 pregame to 6.99 ± 0.07 and 7.13 ± 0.11 during the first and last periods, respectively. Muscle glycogen decreased by 53% postgame (P ≤ 0.05) with ~65% of fast- and slow-twitch fibers depleted of glycogen. Blood lactate increased sixfold (P ≤ 0.05), whereas plasma free fatty acid levels increased 1.5-fold and threefold (P ≤ 0.05) after the first and last periods. Repeated-sprint ability was impaired (~3%; P ≤ 0.05) postgame concomitant with a ~10% decrease in the number of accelerations and decelerations during the second and last periods (P ≤ 0.05).

Conclusions: Our findings demonstrate that a simulated ice hockey match-play scenario encompasses a high on-ice heart rate response and glycolytic loading resulting in a marked degradation of muscle glycogen, particularly in specific sub-groups of fibers. This may be of importance both for fatigue in the final stages of a game and for subsequent recovery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1249/MSS.0000000000002370DOI Listing
October 2020

The "11 for Health in Denmark" intervention in 10- to 12-year-old Danish girls and boys and its effects on well-being-A large-scale cluster RCT.

Scand J Med Sci Sports 2020 Sep 27;30(9):1787-1795. Epub 2020 May 27.

Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark.

Background: The present study investigates the well-being effects for 10- to 12-year-old children  who participated in the school-based intervention "11 for Health in Denmark," which comprises physical activity (PA) and health education. Subgroup analyses were carried out for boys and girls.

Method: Three thousand sixty-one children were randomly assigned to an intervention group (IG) or a control group (CG) by 5:1 cluster randomization by school. 2533 children (mean age 11.5 ± 0.4; 49.7% boys) were assigned to IG and 528 children (mean age 11.4 ± 0.5; 50.8% boys) were assigned to CG. IG participated in the "11 for Health in Denmark" 11-week program, consisting of 2 × 45 min per week of football drills, small-sided games, and health education. CG did not participate in any intervention and continued with their regular education. Before and after the intervention period, both groups answered a shortened version of the multidimensional well-being questionnaire KIDSCREEN-27.

Results: The "11 for Health in Denmark" intervention program had a positive effect on physical well-being in girls (IG: 48.6 ± 8.5 to 50.2 ± 9.3), whereas the improvement was not significant in boys. The program also had a positive impact on well-being scores for peers and social support (IG: 50.2 ± 10.2 to 50.8 ± 10.1), though when analyzed separately in the subgroups of boys and girls the changes were not significant. No between-group differences were found for psychological well-being or school environment.

Conclusion: The intervention program had a positive between-group effect on physical well-being in girls, whereas the change was not significant in boys. The overall scores for peers and social support improved during the intervention period, but no subgroup differences were found.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/sms.13704DOI Listing
September 2020

Effects of a 6-Week Faroese Chain Dance Programme on Postural Balance, Physical Function, and Health Profile in Elderly Subjects: A Pilot Study.

Biomed Res Int 2019 17;2019:5392970. Epub 2019 Jul 17.

Centre of Health Science, Faculty of Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.

The present pilot study investigates the impact of a Faroese chain dance intervention on health profile, mobility, and postural balance in elderly subjects. Healthy elderly subjects (n=27; age 75 ± 5 yrs) were randomised into an intervention group (IG) and a control group (CG). IG performed twice-weekly sessions of Faroese chain dance over 6 weeks. Dancing sessions lasted 30 min in the initial 3 weeks and 45 min in the final 3 weeks. Health profile was determined before and after intervention by measuring blood pressure, resting heart rate, muscle mass, and body fat content. Postural balance was evaluated using the Berg Balance Scale (BBS) and Fullerton Advanced Balance Scale (FAB) tests, while mobility was assessed using the Short Physical Performance Battery (SPPB), the Timed Up & Go (TUG) test, the 6-min walk test, and the 30-s sit-to-stand test. Systolic and diastolic blood pressure were lowered (9 ± 6 and 6 ± 3 mmHg, respectively) in IG, with a tendency (P=0.07) for a greater change score than in CG. Mean arterial pressure declined (P<0.05) by 7 ± 3 mmHg in IG, which tended (P=0.09) to be greater than in CG. IG improved (P<0.05) on BBS and FAB scores by 3.6 ± 2.1% and 15.8 ± 8.3%, with the change score for FAB being greater (P<0.05) than in CG (0.3 ± 1.6). Moreover, the postintervention SPPB score was improved (P<0.05) more in IG (13.9 ± 7.4%) compared to CG, while performance in the 30-s sit-to-stand, 6-min walk, and TUG tests improved (4-15%; P<0.05) in IG only. Body fat content was reduced (P<0.05) from 36.3 ± 2.8% to 34.8 ± 2.8% in IG, with no between-group differences and no change in CG (34.1 ± 2.8% to 33.7 ± 3.1%). In conclusion, a 6-week Faroese chain dance programme lowers blood pressure and improves postural balance and physical function in elderly.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2019/5392970DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6662506PMC
January 2020

Activity Profile, Heart Rate, Technical Involvement, and Perceived Intensity and Fun in U13 Male and Female Team Handball Players: Effect of Game Format.

Sports (Basel) 2019 Apr 19;7(4). Epub 2019 Apr 19.

Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences (SHS), University of Southern Denmark, 5230 Odense, Denmark.

The aim of the study was to compare the activity pattern, heart rate (HR), technical involvement, and subjective perceptions in U13 boys and girls playing team handball in five game formats. Activity pattern, heart rate (HR), technical involvement, perceived fun, and exertion were recorded from four girls teams (n = 24) and four boys teams (n = 24) played during a 1-day tournament consisting of five different game formats of 15-min duration: Medium court size, 4v4 (M4v4), 5v5 (M5v5), and 6v6 (M6v6), and large court size, 5v5 (L5v5) and 6v6 (L6v6). Girls covered more total distance (TD) and high-speed running (HSR, 13-17.9 km·h) on the large court compared to the medium court ( < 0.05; ES = 2.1-3.1 and 1.2-2.5, respectively). Boys covered more distance as HSR and sprinting on the large court compared to the medium court, but only more TD on the large court compared to the medium court with the same number of players, ( < 0.05; ES = 1.0-1.8, 1.0-1.8, and 1.1-1.8, respectively). Team handball for U13 boys and girls is a high-intensity activity irrespective of court size. Increasing the court size with a fixed number of players increased the total distance and HSR, whereas manipulating the number of players on a fixed court size appears to influence technical involvement.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/sports7040090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524368PMC
April 2019

The Arrowhead Agility Test: Reliability, Minimum Detectable Change, and Practical Applications in Soccer Players.

J Strength Cond Res 2020 Feb;34(2):483-494

Center of Research, Education, Innovation and Intervention in Sports, Faculty of Sports, University of Porto, Porto, Portugal.

Rago, V, Brito, J, Figueiredo, P, Ermidis, G, Barreira, D, and Rebelo, A. The arrowhead agility test: Reliability, minimum detectable change, and practical applications in soccer players. J Strength Cond Res 34(2): 483-494, 2020-Four independent studies were conducted to examine the utility of the arrowhead agility test (AAT) to measure change of direction (COD) capacity in soccer players, specifically, (a) intersession reliability and minimum detectable change (n = 24); (b) power-dependent abilities associated with AAT performance (n = 56); and (c) fatigue sensitivity (n = 20); differences between competitive levels and age groups (n = 264). Irrespective of the AAT outcome measure (skillful side, less-skillful side, sum of both), intersession reliability and the ability to detect changes in performance were good (ICC = 0.80-0.83; CV = 1.25-2.21%; smallest worthwhile change, 0.06-0.12 >SEM, 0.01-0.03) except for the asymmetry index. A 15-m sprint explained a significant amount of variance in COD (p < 0.01; R = 0.42). Arrowhead agility test performance did not change from the prematch toward half time (p = 0.21). However, reduced COD performance was observed after an intense period in the second half and after the game, compared with prematch and half-time performance (p < 0.05; effect size [ES] = -0.85 to 0.42). Irrespective of age group, national players were more agile than regional players (p < 0.05; ES = -1.97 to -0.36). Moreover, independently of their competitive level, senior and U18 players had a better performance than U16 (p < 0.05; ES = -2.33 to -0.84), whereas no significant differences were observed between senior and U18. Percentiles were also reported in the results. The AAT is reliable to measure COD in soccer players. The test may simultaneously encompass 15-m sprint testing but should be implemented independently to countermovement jump. Furthermore, the test is sensitive to match-induced fatigue during the second half and discriminates players from different competitive levels.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1519/JSC.0000000000002987DOI Listing
February 2020

Post-Game High Protein Intake May Improve Recovery of Football-Specific Performance during a Congested Game Fixture: Results from the PRO-FOOTBALL Study.

Nutrients 2018 Apr 16;10(4). Epub 2018 Apr 16.

School of Physical Education and Sport Science, University of Thessaly, Karies, 42100 Trikala, Greece.

The effects of protein supplementation on performance recovery and inflammatory responses during a simulated one-week in-season microcycle with two games (G1, G2) performed three days apart were examined. Twenty football players participated in two trials, receiving either milk protein concentrate (1.15 and 0.26 g/kg on game and training days, respectively) (PRO) or an energy-matched placebo (1.37 and 0.31 g/kg of carbohydrate on game and training days, respectively) (PLA) according to a randomized, repeated-measures, crossover, double-blind design. Each trial included two games and four daily practices. Speed, jump height, isokinetic peak torque, and muscle soreness of knee flexors (KF) and extensors (KE) were measured before G1 and daily thereafter for six days. Blood was drawn before G1 and daily thereafter. Football-specific locomotor activity and heart rate were monitored using GPS technology during games and practices. The two games resulted in reduced speed (by 3-17%), strength of knee flexors (by 12-23%), and jumping performance (by 3-10%) throughout recovery, in both trials. Average heart rate and total distance covered during games remained unchanged in PRO but not in PLA. Moreover, PRO resulted in a change of smaller magnitude in high-intensity running at the end of G2 (75-90 min vs. 0-15 min) compared to PLA (P = 0.012). KE concentric strength demonstrated a more prolonged decline in PLA (days 1 and 2 after G1, P = 0.014-0.018; days 1, 2 and 3 after G2, P = 0.016-0.037) compared to PRO (days 1 after G1, P = 0.013; days 1 and 2 after G2, P = 0.014-0.033) following both games. KF eccentric strength decreased throughout recovery after G1 (PLA: P=0.001-0.047-PRO: P =0.004-0.22) in both trials, whereas after G2 it declined throughout recovery in PLA (P = 0.000-0.013) but only during the first two days (P = 0.000-0.014) in PRO. No treatment effect was observed for delayed onset of muscle soreness, leukocyte counts, and creatine kinase activity. PRO resulted in a faster recovery of protein and lipid peroxidation markers after both games. Reduced glutathione demonstrated a more short-lived reduction after G2 in PRO compared to PLA. In summary, these results provide evidence that protein feeding may more efficiently restore football-specific performance and strength and provide antioxidant protection during a congested game fixture.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu10040494DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946279PMC
April 2018

Improved Exercise Tolerance with Caffeine Is Associated with Modulation of both Peripheral and Central Neural Processes in Human Participants.

Front Nutr 2018 12;5. Epub 2018 Feb 12.

Sport and Exercise Science Research Centre, School of Applied Science, London South Bank University, London, United Kingdom.

Background: Caffeine has been shown to enhance exercise performance and capacity. The mechanisms remain unclear but are suggested to relate to adenosine receptor antagonism, resulting in increased central motor drive, reduced perception of effort, and altered peripheral processes such as enhanced calcium handling and extracellular potassium regulation. Our aims were to investigate how caffeine (i) affects knee extensor PCr kinetics and pH during repeated sets of single-leg knee extensor exercise to task failure and (ii) modulates the interplay between central and peripheral neural processes. We hypothesized that the caffeine-induced extension of exercise capacity during repeated sets of exercise would occur despite greater disturbance of the muscle milieu due to enhanced peripheral and corticospinal excitatory output, central motor drive, and muscle contractility.

Methods: Nine healthy active young men performed five sets of intense single-leg knee extensor exercise to task failure on four separate occasions: for two visits (6 mg·kg caffeine vs placebo), quadriceps P-magnetic resonance spectroscopy scans were performed to quantify phosphocreatine kinetics and pH, and for the remaining two visits (6 mg·kg caffeine vs placebo), femoral nerve electrical and transcranial magnetic stimulation of the quadriceps cortical motor area were applied pre- and post exercise.

Results: The total exercise time was 17.9 ± 6.0% longer in the caffeine (1,225 ± 86 s) than in the placebo trial (1,049 ± 73 s,  = 0.016), and muscle phosphocreatine concentration and pH ( < 0.05) were significantly lower in the latter sets of exercise after caffeine ingestion. Voluntary activation (VA) (peripheral,  = 0.007; but not supraspinal,  = 0.074), motor-evoked potential (MEP) amplitude ( = 0.007), and contractility (contraction time,  = 0.009; and relaxation rate,  = 0.003) were significantly higher after caffeine consumption, but at task failure MEP amplitude and VA were not different from placebo. Caffeine prevented the reduction in M-wave amplitude that occurred at task failure ( = 0.039).

Conclusion: Caffeine supplementation improved high-intensity exercise tolerance despite greater-end exercise knee extensor phosphocreatine depletion and H accumulation. Caffeine-induced increases in central motor drive and corticospinal excitability were attenuated at task failure. This may have been induced by the afferent feedback of the greater disturbance of the muscle milieu, resulting in a stronger inhibitory input to the spinal and supraspinal motor neurons. However, causality needs to be established through further experiments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnut.2018.00006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5816050PMC
February 2018

Sodium bicarbonate intake improves high-intensity intermittent exercise performance in trained young men.

J Int Soc Sports Nutr 2015 4;12:25. Epub 2015 Jun 4.

Faculty of Natural and Health Sciences, University of the Faroe Islands, Jónas Broncks gøta 25. 3rd floor, Tórshavn, Faroe Islands ; Department of Food and Nutrition, and Sport Science, Center of Health and Human Performance, University of Gothenburg, Gothenburg, Sweden.

Background: Sodium bicarbonate intake has been shown to improve exercise tolerance, but the effects on high-intensity intermittent exercise are less clear. Thus, the aim of the present study was to determine the effect of sodium bicarbonate intake on Yo-Yo intermittent recovery test level 2 performance in trained young men.

Method: Thirteen men aged 23 ± 1 year (height: 180 ± 2 cm, weight: 78 ± 3 kg; VO2max: 61.3 ± 3.3 mlO2 · kg(-1) · min(-1); means ± SEM) performed the Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2) on two separate occasions in randomized order with (SBC) and without (CON) prior intake of sodium bicarbonate (0.4 g · kg(-1) body weight). Heart rate and rating of perceived exertion (RPE) were measured during the test and venous blood samples were taken frequently.

Results: Yo-Yo IR2 performance was 14 % higher (P = 0.04) in SBC than in CON (735 ± 61 vs 646 ± 46 m, respectively). Blood pH and bicarbonate were similar between trials at baseline, but higher (P = 0.003) immediately prior to the Yo-Yo IR2 test in SBC than in CON (7.44 ± 0.01 vs 7.32 ± 0.01 and 33.7 ± 3.2 vs 27.3 ± 0.6 mmol · l(-1), respectively). Blood lactate was 0.9 ± 0.1 and 0.8 ± 0.1 mmol · l(-1) at baseline and increased to 11.3 ± 1.4 and 9.4 ± 0.8 mmol · l(-1) at exhaustion in SBC and CON, respectively, being higher (P = 0.03) in SBC. Additionally, peak blood lactate was higher (P = 0.02) in SBC than in CON (11.7 ± 1.2 vs 10.2 ± 0.7 mmol · l(-1)). Blood glucose, plasma K(+) and Na(+) were not different between trials. Peak heart rate reached at exhaustion was 197 ± 3 and 195 ± 3 bpm in SBC and CON, respectively, with no difference between conditions. RPE was 7% lower (P = 0.003) in SBC than in CON after 440 m, but similar at exhaustion (19.3 ± 0.2 and 19.5 ± 0.2).

Conclusion: In conclusion, high-intensity intermittent exercise performance is improved by prior intake of sodium bicarbonate in trained young men, with concomitant elevations in blood alkalosis and peak blood lactate levels, as well as lowered rating of perceived exertion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12970-015-0087-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4475610PMC
March 2016