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Pinna M.,University of Cagliari | Roberto S.,University of Cagliari | Milia R.,University of Cagliari | Marongiu E.,University of Cagliari | And 6 more authors.
Nutrients | Year: 2014

The beneficial effects of beetroot juice supplementation (BJS) have been tested during cycling, walking, and running. The purpose of the present study was to investigate whether BJS can also improve performance in swimmers. Fourteen moderately trained male master swimmers were recruited and underwent two incremental swimming tests randomly assigned in a pool during which workload, oxygen uptake (VO2), carbon dioxide production (VCO2), pulmonary ventilation (VE), and aerobic energy cost (AEC) of swimming were measured. One was a control swimming test (CSW) and the other a swimming test after six days of BJS (0.5l/day organic beetroot juice containing about 5.5 mmol of NO3 -). Results show that workload at anaerobic threshold was significantly increased by BJS as compared to the CSW test (6.3 ± 1 and 6.7 ± 1.1 kg during the CSW and the BJS test respectively). Moreover, AEC was significantly reduced during the BJS test (1.9 ± 0.5 during the SW test vs. 1.7 ± 0.3 kcal·kg-1·h-1 during the BJS test). The other variables lacked a statistically significant effect with BJS. The present investigation provides evidence that BJS positively affects performance of swimmers as it reduces the AEC and increases the workload at anaerobic threshold. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source

Nikolaidis P.T.,Hellenic Army Academy | Torres-Luque G.,University of Jaen | Chtourou H.,Tunisian Research Laboratory Sports Performance Optimisation | Clemente-Suarez V.J.,European University at Madrid | And 2 more authors.
Movement and Sports Sciences - Science et Motricite | Year: 2016

Purpose: The aim of the present study was to examine the effect of age on the relationship between jumping and cycling tests of short-term power in team handball (TH) players. Methods: A cross-sectional study was conducted, in which adolescent and adult TH players (n = 96, age 19.6±6.9 yrs, body mass 75.8±14.1 kg, height 1.78±0.10, mean±standard deviation) performed four jumping tests (i.e., squat jump, countermovement jump, Abalakov jump and a 30-s Bosco test), and two tests on cycle ergometer (i.e. force-velocity (F-v) test and Wingate anaerobic test (WAnT)). Heart rate (HR) was monitored during Bosco test and WAnT. Participants were classified into four age groups (12.1-15.0 yrs, U15; 15.1-18.0 yrs, U18; 18.1-25.0 yrs, U25; and 25.1-35.0 yrs, O25). Results: Differences of moderate to large magnitude among groups were observed with regards to all variables of the F-v test, WAnT and jumping tests, in which the older groups had higher scores in all variables than their younger counterparts (p < 0.05). Correlation between mean power in WAnT (8.0±1.0 W.kg-1) and Bosco test (29.3±7.1 W.kg-1) was r = 0.70 (p < 0.001) in the total sample (ranging from r = 0.43, p = 0.075 in O25 to r = 0.72 in U15, p < 0.001). Correlation between HR in WAnT (179±12 bpm) and Bosco test (162±14 bpm) was r = 0.75 (p < 0.001) in the total sample (ranging from r = 0.65, p < 0.001 in U18 to r = 0.81 in O25, p < 0.001). Conclusions: These findings might help TH coaches and fitness trainers to monitor short-term power of their athletes and to use properly cycling and jumping tests. © ACAPS, EDP Sciences, 2016. Source

Nikolaidis P.T.,Hellenic Army Academy | Nikolaidis P.T.,Exercise Physiology Laboratory | Chtourou H.,Tunisian Research Laboratory Sports Performance Optimisation | Torres-Luque G.,University of Jaen | And 4 more authors.
Journal of Human Kinetics | Year: 2015

The aim of this study was to examine changes in physical attributes, physiological characteristics and responses that occurred in a simulated combat during a six-week preparatory period in young taekwondo athletes. Seven athletes (age 12.17 ±1.11 years) were examined before (pre-intervention) and after (post-intervention) a preparatory period for physical fitness and physiological responses to a 2×90 s simulated bout with a 30 s rest period. The heart rate (HR) was monitored during the simulated combat, and handgrip muscle strength (HMS) along with the countermovement jump (CMJ) were recorded before and after the combat. When compared with pre-intervention values, in post-intervention we observed a decrease in body mass, body fat percentage, and the HR at rest and during recovery after a 3 min step test, and an increase in maximal velocity of the cycle ergometer force-velocity test, the CMJ and mean power during the 30 s continuous jumping test (p<0.05). Furthermore, HR responses to a simulated combat were lower in the post-intervention session (p<0.05). CMJ values increased after the bout in both pre and post-intervention, with higher absolute values in the latter case (p<0.05), whereas there was no difference in HMS. Based on these findings, it can be concluded that the acute physiological responses to a simulated taekwondo combat vary during a season, which might be explained by changes in physical fitness. © 2015 Pantelis T. Nikolaidis et al., published by De Gruyter Open. Source

Haddad M.,Tunisian Research Laboratory Sports Performance Optimisation | Chaouachi A.,Tunisian Research Laboratory Sports Performance Optimisation | Wong D.P.,The Hong Kong Institute of Education | Castagna C.,Football Training and Biomechanics Laboratory | And 4 more authors.
European Journal of Sport Science | Year: 2014

The aim of this study was to examine the influence of exercise intensity and session duration on rating of perceived exertion (RPE) in adolescent Taekwondo (TKD) athletes. Twelve male youth competitive TKD athletes, aged between 13 and 18 years took part in this study. Training data (368 individual sessions) were collected during the 12 weeks of the pre-competitive TKD season. Daily training load was calculated using the heart rate and the session-RPE. Exercise intensity was also classified in five zones [i.e. 50-60%, 61-70%, 71-80%, 81-90% and 91-100% of maximal heart rate (HRmax)] and the time spent in each zone was expressed as percentage of total session time. The analysis of variance showed a significant main effect for zone (p<0.001) with most of the time (69%) spent at intensities between 61 and 90% of HRmax, and only 10% spent above 91% (mean differences compared to the other zones ranging from -6.6% versus zone 1 to -14.8% versus zone 3; p<0.0001). The individual correlation between session-RPE and HR-based methods were moderate to large. The stepwise multiple regression showed that RPE was influenced mainly by the time spent in the high intensity zone that explained 22.1% of the variance in RPE. Session duration accounted for only an additional 3.2%. The results suggest the time spent at high-intensity (i.e. between 91 and 100% HRmax) and only marginally the session duration influences the RPE referred to the whole training session. This seems to confirm that the determination of the TL multiplying the RPE and session duration is acceptable. © 2014 Copyright European College of Sport Science. Source

Chaouachi A.,Tunisian Research Laboratory Sports Performance Optimisation | Poulos N.,Tunisian Research Laboratory Sports Performance Optimisation | Abed F.,Academy for Sports Excellence | Turki O.,Tunisian Research Laboratory Sports Performance Optimisation | And 4 more authors.
Applied Physiology, Nutrition and Metabolism | Year: 2011

Whereas muscle potentiation is consistently demonstrated with evoked contractile properties, the potentiation of functional and physiological measures is inconsistent. The objective was to compare a variety of conditioning stimuli volumes and intensities over a 15-min recovery period. Twelve volleyball players were subjected to conditioning stimuli that included 10 repetitions of half squats with 70% of 1-repetition maximum (RM) (10 × 70), 5 × 70, 5 × 85, 3 × 85, 3 × 90, 1 × 90, and control. Jump height, power, velocity, and force were measured at baseline, 1, 3, 5, 10, and 15 min. Data were analysed with a 2-way repeated measure ANOVA and magnitude-based inferences. The ANOVA indicated significant decreases in jump height, power, and velocity during recovery. This should not be interpreted that no potentiation occurred. Each dependent variable reached a peak at a slightly different time: peak jump height (2.8 ± 2.3 min), mean power (3.6 ± 3.01 min), peak power (2.5 ± 1.8 min), and peak velocity (2.5 ± 1.8 min). Magnitude-based inference revealed that both the 5 × 70 and 3 × 85 protocol elicited changes that exceeded 75% likelihood of exceeding the smallest worthwhile change (SWC) for peak power and velocity. The 10 × 70 and the 5 × 70 had a substantial likelihood of potentiating peak velocity and mean power above the SWC, respectively. Magnitude-based inferences revealed that while no protocol had a substantial likelihood of potentiating the peak vertical jump, the 5 × 70 had the most consistent substantial likelihood of increasing the peak of most dependent variables. We were unable to consistently predict if these peaks occurred at 1, 3, or 5 min poststimulation, though declines after 5 min seems probable. Source

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