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1.  The Effect of Ramadan Fasting on Physical Performances, Mood State and Perceived Exertion in Young Footballers 
Asian Journal of Sports Medicine  2011;2(3):177-185.
This study was designed to assess the effects of Ramadan fasting on the profile of mood state and perceived exertion in young soccer players and aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests.
Twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests on three different occasions: one-week before Ramadan (BR), the second week (SWR) and the fourth week (ER) of Ramadan. The total distance (TD) covered and the estimated maximal aerobic velocity (MAV) during the Yo-Yo test were recorded. During the RSA test, peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) were calculated. During the Wingate test, peak (Ppeak) and mean (Pmean) powers and fatigue index (FI) were recorded.
TD and MAV (P=0.01) during the Yo-Yo test and PP (P=0.01, P=0.004, P=0.001, P=0.01, P=0.03 for sprints 1, 2, 3, 4, and 5, respectively) and Wtotal (P=0.02) during the RSA test were significantly higher during BR than ER. Furthermore, muscle fatigue during the RSA test increased significantly from BR to ER (P=0.01). Ppeak and Pmean during the Wingate test decreased significantly from BR to SWR and ER (P<0.0005). FI was higher during SWR (P=0.001) and ER (P<0.0005) than BR. In addition, rating of perceived exertion scores and fatigue estimated by the profile of mood state questionnaire were higher during Ramadan in comparison with BR.
The present study suggests that both aerobic and anaerobic performances during the Yo-Yo, the RSA and the Wingate tests were affected by Ramadan fasting in young soccer players.
PMCID: PMC3289213  PMID: 22375237
Ramadan Fasting; Fatigue; Aerobic Exercise; Anaerobic Exercise; Footballers
2.  The Effects of Music on High-intensity Short-term Exercise in Well Trained Athletes 
Asian Journal of Sports Medicine  2012;3(4):233-238.
The purpose of this investigation was to assess the effects of listening to music during warm-up on short-term supramaximal performances during the 30-s Wingate test in highly trained athletes.
Twelve young male athletes (20.6±1.8 yrs, 177±4.4 cm and 72.3±5.3 kg) underwent two Wingate tests in separate sessions with a recovery period of 48 h in-between, either after a 10 min of warm-up with (MWU) or without (NMWU) music. High tempo music (>120 to 140bpm) was selected for the study. Heart rate (HR) and rate of perceived exertion (RPE) were recorded after the warm-up (for HR = average of warm-up) and immediately after the Wingate test.
HR, RPE and the fatigue index during the Wingate test are not affected by the incorporation of music during warm-up. However, power output (Ppeak and Pmean) was significantly higher after MWU than NMWU (P<0.05). The relative increases were 4.1 ± 3.6 and 4.0 ± 3.7 W·kg−1 for Ppeak and Pmean respectively. These findings demonstrated the beneficial effect of music during warm-up on short-term supramaximal performances.
As it's a legal method and an additional aid, music may be used during warm-up before performing activities requiring powerful lower limbs’ muscles contractions during short-term supramaximal exercises.
PMCID: PMC3525819  PMID: 23342221
Anaerobic Threshold; Warm-up Exercise; Wingate test; Music
3.  Repeated Sprint Ability in Elite Water Polo Players and Swimmers and its Relationship to Aerobic and Anaerobic Performance 
The purpose of this study was to determine indices of swimming repeated sprint ability (RSA) in 19 elite water polo players compared to 16 elite swimmers during a repeated sprint swimming test (RST), and to examine the relationships between these indices and aerobic and anaerobic performance capabilities in both groups. Indices of RSA were determined by the ideal sprint time (IS), the total sprint time (TS), and the performance decrement (PD) recorded during an 8 x 15-m swimming RST. Single long - (800-m) and short-(25-m) distance swim tests were used to determined indices of aerobic and anaerobic swimming capabilities, respectively. The water polo players exhibited lower RSA swimming indices, as well as lower scores in the single short and long swim distances, compared to the swimmers. Significant relationships were found between the 25- m swim results and the IS and the TS, but not the PD of both the swimmers and the water polo players. No significant relationships were found between the 800-m swim results and any of the RSA indices in either the swimmers or the water polo players. No significant relationships were found between the 25-m and the 800-m swim results in either the swimmers or the water polo players. The results indicate that swimmers posses better RSA as well as higher anaerobic and aerobic capabilities, as reflected by the single short- and long-distance swim tests, compared to water polo players. The results also indicate that, as for running and cycling, repeated sprint swim performance is strongly related to single sprint performance.
Key PointsElite water polo players demonstrated lower repeated sprint ability (RSA), aerobic and anaerobic capabilities compared to elite swimmers.A 25-m swim trial correlated significantly with ideal sprint time and total sprint time, emphasizing the important contribution of anaerobic metabolism for these exercise types in both water polo players and swimmers.800-m swim results did not correlate with RSA or 25-m swim results, demonstrating a discrepancy in exercise-dependent energy sources between the long distance swim and the other two testing procedures.
PMCID: PMC3873665  PMID: 24421734
Intermittent activity; continuous effort; recovery; training
4.  Longitudinal Study of Repeated Sprint Performance in Youth Soccer Players of Contrasting Skeletal Maturity Status 
The purpose of the study was to evaluate the developmental changes in performance in a repeated-sprint ability (RSA) test in young soccer players of contrasting maturity status. A total of 83 regional level Portuguese youth soccer players, aged 11-13 years at baseline was assessed annually. Stature, body mass, 7x34.2-m sprint protocol (25-s active recovery), 20-m multi-stage continuous shuttle endurance run and counter-movement jump (CMJ) without the use of the arms were measured. Fat-free mass (FFM) was determined by age and gender-specific formulas. Developmental changes in total sprint time across ages were predicted using multilevel modeling. Corresponding measurements were performed on an independent cross-sectional subsample of 52 youth soccer players 11-17 years to evaluate the predictive model. CA, CA2, maturational status (SA-CA), body size (mass and stature), FFM, aerobic endurance, lower limb explosive strength and annual volume training significantly improved the statistical fit of the RSA multilevel model. In ‘late’ maturing athletes, the best model for predicting change in RSA was expressed by the following equation: 86.54 - 2.87 x CA + 0.05 x CA2 - 0.25 x FFM + 0.15 x body mass + 0.05 x stature - 0.05 x aerobic endurance - 0.09 x lower limb explosive strength - 0.01 x annual volume training. The best fitting models for players who were ‘on time’ and ‘early’ maturing were identical to the best model for late maturing players, less 0.64 seconds and 1.74 seconds, respectively. Multilevel modeling provided performance curves that permitted the prediction of individual RSA performance across adolescent years in regional level soccer players.
Key pointsRepeated-sprint ability tests are a valuable sport-specific field test of sprint performance in youth soccer players. Here, the test had reasonable reliability and can be useful to trainers and coaches in the assessment of young athletes and in monitoring changes over time.The total sprint time of youth soccer players advanced in biological maturation improves more, on average, than that of players who are on time (average) and late in maturation. The performance difference between early and late maturing players is consistent after about 13 years of age.Multilevel modeling is a promising statistical technique for analyzing the development of functional capacity in a sport. It has the potential to provide useful information to assist trainers and coaches in evaluating and facilitating the development of individual players.
PMCID: PMC3737923  PMID: 24149342
young athletes; multilevel modeling; growth; maturation; short-term effort
5.  Shuttle-Run Sprint Training in Hypoxia for Youth Elite Soccer Players: A Pilot Study 
The purposes of the present study were to investigate if a) shuttle-run sprint training performed in a normobaric hypoxia chamber of limited size (4.75x2.25m) is feasible, in terms of producing the same absolute training load, when compared to training in normoxia, and b) if such training improves the repeated sprint ability (RSA) and the Yo-Yo intermittent recovery (YYIR) test outcome in young elite soccer players. Players of an elite soccer training Centre (age: 15.3 ± 0.5 years, height: 1.73 ± 0.07 m, body mass: 62.6 ± 6.6 kg) were randomly assigned to a hypoxia or a normoxia training group. Within a 5-week period, players, who were not informed about the hypoxia intervention, performed at least 7 sessions of identical shuttle-run sprint training either in a normal training room (FiO2 = 20.95%) or in a hypoxic chamber (FiO2 = 14.8%; approximately 3300m), both equipped with the same floor. Each training session comprised 3 series of 5x10s back and forth sprints (4.5m) performed at maximal intensity. Recovery time between repetitions was 20s and between series 5min. Before and after the training period the RSA (6 x 40m shuttle sprint with 20 s rest between shuttles) and the YYIR test were performed. The size of the chamber did not restrict the training intensity of the sprint training (both groups performed approximately 8 shuttles during 10s). Training in hypoxia resulted in a lower fatigue slope which indicates better running speed maintenance during the RSA test (p = 0.024). YYIR performance increased over time (p = 0.045) without differences between groups (p > 0.05). This study showed that training intensity of the shuttle-run sprint training was not restricted in a hypoxic chamber of limited size which indicates that such training is feasible. Furthermore, hypoxia compared to normoxia training reduced the fatigue slope during the RSA test in youth soccer players.
Key PointsShuttle-run sprint training is feasible in hypoxic chambers of limited size (i.e., 4.75x2.25m).Hypoxia sprint training (RSH), in comparison to normoxia training, might lead to better running speed maintenance during the repeated sprint ability test.
PMCID: PMC4234940  PMID: 25435763
Altitude training; football; high intensity training; repeated sprint ability; Yo-Yo test
6.  Pronounced Muscle Deoxygenation During Supramaximal Exercise Under Simulated Hypoxia in Sprint Athletes 
The purpose of this study was to determine whether acute hypoxia alters the deoxygenation level in vastus lateralis muscle during a 30 s Wingate test, and to compare the muscle deoxygenation level between sprint athletes and untrained men. Nine male track sprinters (athletic group, VO2max 62.5 ± 4.1 ml/kg/min) and 9 healthy untrained men (untrained group, VO2max 49.9 ± 5.2 ml·kg-1·min-1) performed a 30 s Wingate test under simulated hypoxic (FIO2 = 0.164 and PIO2 = 114 mmHg) and normoxic conditions. During the exercise, changes in oxygenated hemoglobin (OxyHb) in the vastus lateralis were measured using near infrared continuous wave spectroscopy. Decline in OxyHb, that is muscle deoxygenation, was expressed as percent change from baseline. Percutaneous arterial oxygen saturation (SpO2), oxygen uptake (VO2), and ventilation (VE) were measured continuously. In both groups, there was significantly greater muscle deoxygenation, lower SpO2, lower peakVO2, and higher peakVE during supramaximal exercise under hypoxia than under normoxia, but no differences in peak and mean power output during the exercise. Under hypoxia, the athletic group experienced significantly greater muscle deoxygenation, lower SpO2, greater decrement in peakVO2 and increment in peakVE during the exercise than the untrained group. When the athletic and untrained groups were pooled, the increment of muscle deoxygenation was strongly correlated with lowest SpO2 in the 30 s Wingate test under hypoxia. These results suggest that acute exposure to hypoxia causes a greater degree of peripheral muscle deoxygenation during supramaximal exercise, especially in sprint athletes, and this physiological response would be explained mainly by lower arterial oxygen saturation.
Key pointsThe deoxygenation trends in the vastus lateralis muscle during 30 s Wingate test in track sprinters and untrained men under simulated hypoxic and normoxic conditions was investigated using near infrared spectroscopy.Acute hypoxia caused a greater degree of peripheral muscle deoxygenation than normoxia, whereas there were no changes in performance such as power output during 30 s Wingate test.Sprint athletes show a greater degree of peripheral muscle deoxygenation during 30 s Wingate test in hypoxia when compared with untrained subjects.A larger difference in muscle deoxygenation between hypoxia and normoxia is accompanied by lowest SpO2 at the 30 s Wingate test in hypoxia.
PMCID: PMC3761931  PMID: 24149959
NIRcws; muscle deoxygenation; hypoxic; 30s Wingate test; athletes
7.  The Relationship Between the Yo-Yo Tests, Anaerobic Performance and Aerobic Performance in Young Soccer Players 
Journal of Human Kinetics  2012;35:81-88.
The purposes of this study were to determine the relationship between performance in the Yo-Yo intermittent recovery test level 1 (YIRT1), the Yo-Yo intermittent recovery test level 2 (YIRT2) and the Yo-Yo endurance test (continuous) (YET) with maximal oxygen uptake (VO2max) and Wingate anaerobic performance (WaNT) test results in young soccer players (age 15.00 ± 0.0 years, body height 176.3 ± 4.2 cm and body mass 68.1 ± 3.6 kg). An ergospirometry device was used during the treadmill test (TRT) to determine VO2max. At the end of the study, significant differences were found between the Yo-Yo tests and TRT in terms of HRmax (TRT = 195,92, YIRT1 = 197,83, YIRT2 = 198,5 YET = 198) (p > 0.05). While there were moderate correlations between VO2max and YIRT 1–2 performances (respectively, r = 0.56, r = 0.53), there was only a weak relationship between VO2max and YET performance (r = 0.43) (distance covered). There were also moderate significant negative correlations between performance in the YIRT2 and peak power measured in the WaNT (r = −0.55), although there were no significant correlations between performance in the three tests and average power. A moderate negative correlation was found between performance in the YIRT2 and Fatigue index (FI) (r = −0,66). In conclusion, the YIRT2 may be a more suitable field test for determining both aerobic and anaerobic performance in soccer players.
PMCID: PMC3588685  PMID: 23486008
Yo-Yo Tests; Wingate test; VO2max; soccer; anaerobic power
8.  A Practical Model of Low-Volume High-Intensity Interval Training Induces Performance and Metabolic Adaptations That Resemble ‘All-Out’ Sprint Interval Training 
Recently, a novel type of high-intensity interval training known as sprint interval training has demonstrated increases in aerobic and anaerobic performance with very low time commitment. However, this type of training program is unpractical for general populations. The present study compared the impact of a low-volume high-intensity interval training to a "all-out" sprint interval training. Twenty-four active young males were recruited and randomized into three groups: (G1: 3-5 cycling bouts ˟ 30-s all-out with 4 min recovery; G2: 6- 10 cycling bouts ˟ 125% Pmax with 2 min recovery) and a non-trained control group. They all performed a VO2max test, a time to exhaustion at Pmax (Tmax) and a Wingate test before and after the intervention. Capillary blood lactate was taken at rest, 3, and 20 min after the Wingate trial. Training was performed 3 sessions per week for 4 weeks. In G1, significant improvements (p < 0.05) following training were found in VO2max (9.6%), power at VO2max (12.8%), Tmax (48.4%), peak power output (10.3%) and mean power output (17.1%). In G2, significant improvements following training were found in VO2max (9.7%), power at VO2max (16.1%), Tmax (54.2%), peak power output (7.4%; p < 0.05), but mean power output did not change significantly. Blood lactate recovery (20th min) significantly decreased in G1 and G2 when compared with pre-testing and the CON group (p < 0.05). In conclusion, the results of the current study agree with earlier work demonstrating the effectiveness of 30-s all-out training program to aerobic and anaerobic adaptations. Of substantial interest is that the low volume high intensity training provides similar results but involves only half the intensity with double the repetitions.
Key pointsGiven the markedly lower training volume in the training groups, our results suggest that intense interval training is indeed a time-efficient strategy to induce rapid metabolic and performance adaptations.The results demonstrate that a practical low-volume HIT program is effective for improving metabolic and performance adaptations that resemble many of the same performance gains occurred in all-out SIT protocol.
PMCID: PMC3737829  PMID: 24150635
Wingate test; repeated sprints; blood lactate; training adaptations.
9.  Relationship between Repeated Sprint Ability and Aerobic Capacity in Professional Soccer Players 
The Scientific World Journal  2013;2013:952350.
Aim. The aim of the present study was to investigate the relationship between maximal aerobic capacity (VO2 max) and repeated sprint ability (RSA) in a group of professional soccer players. Methods. Forty-one professional soccer players (age 23 ± 4 yrs, height 180.0 ± 5.3 cm, weight 79.6 ± 5.3 kg) were required to perform tests to assess RSA and VO2 max on two separate days with at least 48 hr rest between testing sessions. Each player performed a treadmill test to determine their VO2 max and a test for RSA involving the players completing 6 × 40 m sprints (turn after 20 m) with 20 s active recovery between each sprint. Results. There was a significant negative correlation between body mass normalised VO2 max and mean sprint time (RSAmean) (r = −0.655; P < 0.01) and total sprint time (RSAtotal) (r = −0.591, P < 0.01). Conclusion. Results of the current study indicate that VO2 max is one important factor aiding soccer players in the recovery from repeated sprint type activities.
PMCID: PMC3807849  PMID: 24198732
10.  Myocardial Performance and Aortic Elastic Properties in Elite Basketball and Soccer Players: Relationship with Aerobic and Anaerobic Capacity 
The aims of the present study were to examine the myocardial performance index and aortic elastic properties of athletes engaged in ball sports and to determine their relationships with aerobic and anaerobic characteristics. Standard M-mode and Doppler echocardiography, maximal oxygen uptake and 30 sec Wingate tests were performed for 32 elite male athletes (12 basketball and 20 soccer players) and 12 healthy sedentary volunteers. Data were analyzed by ANOVA and partial correlation coefficient tests. Absolute values of left ventricular internal diameter, left ventricular posterior wall and interventricular septum thicknesses in diastole were significantly (p < 0.05-0.01) greater in athletes than in controls. The left ventricular internal diameter corrected by body surface area was also greater (p < 0.05-0.01) in the athletes compared with the controls. Absolute and body surface area corrected left ventricular mass were significantly greater (p < 0.05-0.001) in athletes than in controls. Isovolumetric relaxation time was higher (p < 0.01) in soccer players than in controls. There were no significant differences among the groups for myocardial performance index and aortic elastic properties. Left ventricular mass index was poorly correlated (p < 0.01) with VO2max (r = 0.410), peak power (r = 0.439) and average power (r = 0.464) in the athletes. Poor correlations (r = 0.333-0.350, p < 0.05) were also observed between aortic elastic properties and average power in athletes. Myocardial performance index and aortic elastic properties are not different in athletes involved in this study compared with sedentary subjects. Aerobic and anaerobic capacities of the athletes used in this study are poorly explained by these resting echocardiographic findings.
Key PointsLeft ventricular internal diameter, left ventricular posterior wall and interventricular septum thicknesses in diastole, and left ventricular mass were significantly greater in athletes than in controls.There were no remarkable differences in Doppler velocities and time intervals between athletes and controls.Myocardial performance index and aortic elastic properties are not different in athletes compared with sedentary subjects.Aerobic and anaerobic parameters of athletes are poorly explained by resting echocardiographic characteristics.VO2max and anaerobic power indices are variables that better determines left ventricular mass developed in ball sport specific training.
PMCID: PMC3880886  PMID: 24431975
Athletes’ heart; cardiac function; aortic elastic properties; oxygen uptake; power
11.  Time-of-Day Effects on EMG Parameters During the Wingate Test in Boys 
In boys, muscle power and strength fluctuate with time-of-day with morning nadirs and afternoon maximum values. However, the exact underlying mechanisms of this daily variation are not studied yet. Thus, the purpose of this study was to examine the time-of-day effects on electromyographic (EMG) parameters changes during a Wingate test in boys. Twenty-two boys performed a 30-s Wingate test (measurement of muscle power and fatigue) at 07:00 and 17:00-h on separate days. Surface EMG activity was recorded in the Vastus lateralis, rectus femoris and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root-mean-square (RMS) and mean-power-frequency (MPF) were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Muscle power (8.22 ± 0.92 vs. 8.75 ± 0.99 W·kg-1 for peak power and 6.96 ± 0. 72 vs. 7.31 ± 0.77 W·kg-1 for mean power, p < 0.001) and fatigue (30.27 ± 7.98 vs. 34.5 ± 10. 15 %, p < 0.05) during the Wingate test increased significantly from morning to evening. Likewise, MPF (102.14 ± 18.15 vs. 92.38 ± 12.39 Hz during the first 5-s, p < 0.001) and NME (4.78 ± 1.7 vs. 3.88 ± 0.79 W·mV-1 during the first 5-s, p < 0.001) were higher in the evening than the morning; but no significant time-of-day effect was noticed for RMS. Taken together, these results suggest that peripheral mechanisms are more likely the cause of the child’s diurnal variations of muscle power and fatigue during the Wingate test.
Key pointsIn boys, performances during the Wingate test fluctuate with the time-of-day.MPF and NME are higher in the evening during the Wingate cycling test.RMS is unaffected by the time-of-day.The evening improvement in muscle power and fatigue is due to an enhancement of the muscle contractile properties.
PMCID: PMC3737921  PMID: 24149343
Dkwdurnal variation; muscle power; muscle fatigue; electromyography; pre-pubertal
12.  Physical performance changes after unsupervised training during the autumn/spring semester break in competitive tennis players 
British Journal of Sports Medicine  2007;41(11):705-710.
All competitive tennis players take time away from coaches throughout the year; however, little information is available as to the short‐term physiological effect of these breaks.
The purpose of this investigation was to evaluate the impact of a 5 week off‐campus structured, yet unsupervised, break from regular training in top collegiate tennis players.
A nationally ranked collegiate NCAA Division I male tennis team (n = 8) performed a test battery in December and again in January after a 5 week period of recommended, yet unsupervised, training. The tests performed were 5, 10 and 20 m sprints, spider agility test, medicine ball power throws, standing long jump, Wingate anaerobic power test, VO2max, push‐up and sit‐up test, grip strength and range of motion (ROM) measures (goniometer) of the shoulder, hip, hamstring and quadriceps.
Paired t tests (p<0.05) showed significant decreases in mean (SEM) Wingate power measurements in Watts/kg (pre: 8.35 (0.19) w/kg ; post: 7.80 (0.24) w/kg ), minimum Wingate power (pre: 5.89 (0.27) w/kg; post: 5.10 (0.38) w/kg) and VO2max values (pre: 53.90 (1.11) ml/kg/min; post: 47.86 (1.54) ml/kg/min). A significant increase was seen in the athlete's fatigue index (pre: 44.26 (2.85)%; post: 51.41 (3.53)%), fastest 5 m (pre: 1.07 (0.03) s; post: 1.12 (0.02) s), 10 m (pre: 1.79 (0.03) s; post: 1.84 (0.04) s) and 20 m (pre: 3.07 (0.05) s; post: 3.13 (0.05) s) sprint times. No significant differences were seen for the other variables tested.
These results suggest that a 5 week interruption of normal training can result in significant reductions in speed, power and aerobic capacity in competitive tennis players, likely owing to poor compliance with the prescribed training regimen. Therefore, coaches and trainers might benefit from techniques (eg, pre‐ and post‐testing) requiring athletes' to have accountability for unsupervised workouts.
PMCID: PMC2465299  PMID: 17562748
13.  Relationship between Nutrition Knowledge and Physical Fitness in Semiprofessional Soccer Players 
Scientifica  2014;2014:180353.
Whereas nutrition has a crucial role on sport performance, it is not clear to what extent nutrition knowledge is associated with physical fitness. The aim of this study was to examine the current level of nutrition knowledge of soccer players and whether this level is associated with physical fitness. Soccer players (n = 185, aged 21.3 ± 4.9 yr, weight 72.3 ± 8.4 kg, and height 177.5 ± 6.4 cm) performed a battery of physical fitness tests (sit-and-reach test, SAR; physical working capacity in heart rate 170, PWC170; and Wingate anaerobic test, WAnT) and completed an 11-item nutrition knowledge questionnaire (NKQ). Low to moderate Pearson correlations (0.15 < r < 0.34, p < 0.05) of NKQ with age, weight, height, fat free mass (FFM), SAR, peak power, and mean power of WAnT were observed. Soccer players with high score in NKQ were older (4.4 yr (2.2; 6.6), mean difference (95% confidence intervals)) and heavier (4.5 kg (0.6; 8.3)) with higher FFM (4.0 kg (1.1; 6.8)) and peak power (59 W (2; 116)) than their counterparts with low score. The moderate score in the NKQ suggests that soccer players should be targeted for nutrition education. Although the association between NKQ and physical fitness was low to moderate, there were indications that better nutrition knowledge might result in higher physical fitness and, consequently, soccer performance.
PMCID: PMC4130195  PMID: 25140277
14.  Relationship Between Repeated Sprint Performance and both Aerobic and Anaerobic Fitness 
Journal of Human Kinetics  2014;40:139-148.
The aims of this study were firstly, to examine the relationship between repeated sprint performance indices and anaerobic speed reserve (AnSR), aerobic fitness and anaerobic power and secondly, to identify the best predictors of sprinting ability among these parameters. Twenty nine subjects (age: 22.5 ± 1.6 years, body height: 1.8 ± 0.1 m, body mass: 68.8 ± 8.5 kg, body mass index (BMI): 22.2 ± 2.1 kg•m-2, fat mass: 11.3 ± 2.9 %) participated in this study. All participants performed a 30 m sprint test (T30) from which we calculated the maximal anaerobic speed (MAnS), vertical and horizontal jumps, 20m multi-stage shuttle run test (MSRT) and repeated sprint test (10 × 15 m shuttle run). AnSR was calculated as the difference between MAnS and the maximal speed reached in the MSRT. Blood lactate sampling was performed 3 min after the RSA protocol. There was no significant correlation between repeated sprint indices (total time (TT); peak time (PT), fatigue index (FI)) and both estimated VO2max and vertical jump performance). TT and PT were significantly correlated with T30 (r=0.63, p=0.001 and r=0.62, p=0.001; respectively), horizontal jump performance (r = −0.47, p = 0.001 and r = −0.49, p = 0.006; respectively) and AnSR (r=−0.68, p= 0.001 and r=−0.70, p=0.001, respectively). Significant correlations were found between blood lactate concentration and TT, PT, and AnSR (r=−0.44, p=0.017; r=−0.43, p=0.018 and r=0.44, p=0.016; respectively). Stepwise multiple regression analyses demonstrated that AnSR was the only significant predictor of the TT and PT, explaining 47% and 50% of the shared variance, respectively. Our findings are of particular interest for coaches and fitness trainers in order to predict repeated sprint performance by using AnSR that can easily identify the respective upper performance limits supported by aerobic and anaerobic power of a player involved in multi-sprint team sports.
PMCID: PMC4096094  PMID: 25031682
aerobic fitness; anaerobic power; vertical jump; horizontal jump; repeated sprint ability
15.  Influence of the Mechanical Properties of Third-Generation Artificial Turf Systems on Soccer Players’ Physiological and Physical Performance and Their Perceptions 
PLoS ONE  2014;9(10):e111368.
The aim of this research was to evaluate the influence of the mechanical properties of artificial turf systems on soccer players’ performance. A battery of perceptive physiological and physical tests were developed on four different structural systems of artificial turf (System 1: Compacted gravel sub-base without elastic layer; System 2: Compacted gravel sub-base with elastic layer; System 3: Asphalt sub-base without elastic layer; System 4: Asphalt sub-base with elastic layer). The sample was composed of 18 soccer players (22.44±1.72 years) who typically train and compete on artificial turf. The artificial turf system with less rotational traction (S3) showed higher total time in the Repeated Sprint Ability test in comparison to the systems with intermediate values (49.46±1.75 s vs 47.55±1.82 s (S1) and 47.85±1.59 s (S2); p<0.001). The performance in jumping tests (countermovement jump and squat jump) and ball kicking to goal decreased after the RSA test in all surfaces assessed (p<0.05), since the artificial turf system did not affect performance deterioration (p>0.05). The physiological load was similar in all four artificial turf systems. However, players felt more comfortable on the harder and more rigid system (S4; visual analogue scale = 70.83±14.28) than on the softer artificial turf system (S2; visual analogue scale = 54.24±19.63). The lineal regression analysis revealed a significant influence of the mechanical properties of the surface of 16.5%, 15.8% and 7.1% on the mean time of the sprint, the best sprint time and the maximum mean speed in the RSA test respectively. Results suggest a mechanical heterogeneity between the systems of artificial turf which generate differences in the physical performance and in the soccer players’ perceptions.
PMCID: PMC4213020  PMID: 25354188
16.  Daily Physical Activity and Physical Fitness in 11-to 15-year-old Trained and Untrained Turkish Boys 
The aims of this study were to assess levels and patterns of physical activity (PA) in relation to age and regular sport activity, and to examine its relationship to physical fitness in trained and untrained boys. One hundred forty-seven 11-to 15- year-old boys (73 trained and 74 untrained) participated in this study. Trained boys, comprised of 26 soccer, 25 handball and 22 volleyball players, had been training regularly for at least one year. The intensity, duration and frequency of PA were assessed from four complete days of heart rate monitoring with 15-seconds sampling intervals. Aerobic fitness was assessed by determining peakVO2 with a portable breath-by-breath gas analyzer (Cosmed K4b2) and the running speeds at fixed lactate concentrations during an incremental running test. Anaerobic fitness was evalu-ated with the Wingate Anaerobic Test. Skinfold thicknesses from eight sites and Tanner stages of pubic hair were also obtained. Based on 15-s heart rate data, instead of continuous activity, multiple short bouts of moderate and vigorous PA, lasting up to one minute, were characteristic of daily PA patterns of both trained and untrained boys. PA levels of trained boys were higher than untrained boys (p < 0.01) and the levels of PA decreased with age and maturation in both groups (p < 0.05). Daily PA variables were related to body fatness in both groups (p < 0.05), but the relationships were not consistent in the trained group. Daily PA variables were also related to aerobic fitness in the untrained group (p < 0.05) and these relationships were somewhat better with vigorous PA, whereas in the trained group, none of the PA variables were related to any of the aerobic fitness indices (p > 0.05). No relationship was observed between PA variables and anaerobic fitness in either group (p> 0.05). It seems that such relationships may somewhat depend on the fitness level of the subjects.
Key pointsPA levels of trained boys were higher than untrained boys and the levels of PA decreased with age and maturation in both groups.Based on the 15-s HR data, instead of continuous activity, multiple short bouts of moderate and vigorous PA, lasting up to one minute, were characteristic of daily PA patterns of both trained and untrained boys.Daily PA variables were related to aerobic fitness in the untrained group and these relationships were somewhat better with vigorous PA (>70% HRR), whereas in the trained group, none of the PA variables were related to any of the aerobic fitness indices.Neither peak nor mean power values were related to any of the daily PA variables in both trained and untrained groups.
PMCID: PMC3737813  PMID: 24150625
Physical activity; training; aerobic and anaerobic fitness; body fatness; children
17.  Effects of the 11+ and Harmoknee Warm-up Programs on Physical Performance Measures in Professional Soccer Players 
The purpose of this study was to examine the effects of the 11+ and HarmoKnee warm-up programs on performance measures in professional soccer players. Thirty-six male professional soccer players (age: 18.9 ± 1.4 years) were divided into 3 groups, the 11+, HarmoKnee and control group (n = 12 per group). The experimental groups performed the programs 3 times per week for 2 months (24 sessions), whereas the control group only performed their regular soccer training. The performance tests carried out were: 10m speed tests with and without a ball, 20m single sprint, vertical jump, Wall-Volley and Illinois agility tests. The 11+ group demonstrated significant increases from pre-to-post time points in the vertical jump (3.7%), Wall- Volley (5.4%) and Illinois agility tests (1.7%), while the HarmoKnee group showed a significant increase in Wall-Volley test, with a 5.2% increase. The repeated measures analysis revealed differences between the groups (large effect size) in the 11+ and HarmoKnee groups, compared to the control group, in 10m speed tests with and without a ball, 20m single sprint and Illinois agility tests (p < 0.05). Thus 8-weeks performing the 11+ warm-up program can enhance jump height, agility and soccer skill while the HarmoKnee program generally only improves soccer skill in young professional male soccer players.
Key PointsThe 11+ improves performance by means of Illinois agility, vertical jump and Wall-Volley tests whereas HarmoKnee improves Wall-Volley test. Incorporating 11+ as a part of the warm-up program by the young teams would be beneficial in agility, leg power and soccer skill respectively.Further modification of both programs may be required to fully realize the players' speed performance potential.Data from this research can be helpful for soccer trainers in choosing programs to enhance performances in young male professional soccer players.
PMCID: PMC3772593  PMID: 24149156
Performance; vertical jump; Illinois agility test; sprint; Wall-Volley test
18.  Effects and Sustainability of a 13-Day High-Intensity Shock Microcycle in Soccer 
The preseason in soccer is a short period of 6-8 weeks where conditional abilities, technical and tactical elements need to be trained. Therefore, time is lacking to perform long term preparation periods for different abilities, especially endurance training. There is evidence that the implementation of high-intensity shock microcycles in preseason training could be one way to improve physical performance in a short period of time. Therefore, the purpose of the present study was to examine the effects and the sustainability of a high-intensity shock microcycle on soccer specific performance. Over 2 weeks, 12 male soccer players (26.1 ± 4.5 years) performed 12 high-intensity training (HIT) sessions in addition to their usual training. Before (pre), 6 days (6d) and 25 days (25d) after training, subjects performed Counter Movement Jump (CMJ), Repeated-Sprint Ability (RSA) test and Yo-Yo Intermittent Recovery Test Level 2 (YYIR2). Mean sprint time (RSAMean) (cohen’s d = -1.15), percentage decrement score (RSAIndex) (cohen’s d = -1.99) and YYIR2 (cohen’s d = +1.92) improved significantly from pre to 6d. 25d after, values showed a significant reduction for YYIR2 (cohen’s d = -0.81) and small to moderate but not significant increase for RSAMean (cohen’s d = +0.37) and RSAIndex (cohen’s d = +0.7) compared to 6d values. Small but no significant increases were found for CMJ (cohen’s d = +0.33) and no significant and substantial changes were found for RSABest (cohen’s d = -0.07) from pre to 6d. For competitive soccer players, block periodization of HIT offers a promising way to largely improve RSA and YYIR2 in a short period of time. Despite moderate to large decreases in RSAIndex and YYIR2 performance in the 19 day period without HIT, values still remained significantly higher 25d after the last HIT session compared to pre-values. However, it might be necessary to include isolated high-intensity sessions after a HIT training block in order to maintain the higher level of YYIR2 and RSAIndex performance.
Key pointsHIT shock microcycle increases performance in semi-professional soccer players in a short period of time.Despite moderate to large decreases in performance in the 19 day period without HIT, values still remained significantly higher 25d after the last HIT session compared to pre-values.This kind of training block increases YYIR2 performance and the ability to repeated sprints, based on the RSAIndex.
PMCID: PMC3990877  PMID: 24790477
Block periodization; high-intensity training; Yo-Yo Intermittent Recovery Test; repeated-sprint ability
19.  Field and laboratory testing in young elite soccer players 
Aim: To determine if there are correlations between the physical fitness of young soccer players assessed by field and laboratory testing.
Methods: Thirty four male soccer players took part in the study (mean (SD) age 17.5 (1.1) years, height 177.8 (6.7) cm, weight 70.5 (6.4) kg). Maximal oxygen uptake (VO2MAX) during treadmill running and vertical jump height on a force platform were measured in the laboratory. Field tests consisted of a soccer specific endurance test (Bangsbo test) and 30 m sprint with 10 m lap times.
Results: The Bangsbo test correlated with the lowest velocity associated with VO2MAX (vVO2MAX; R2 = 0.55, p<0.001), but not with VO2MAX. Sprint times at 30 m and 20 m were related to peak extension velocity and peak extension force measured during vertical jumping, but not to vertical jump height per se. The jumping force and velocity could explain 46% of the 30 m sprint performance (R2 = 0.46, p<0.001).
Conclusion: The Bangsbo test and 30 m sprint test correlate with vVO2MAX and vertical jump force and velocity respectively. The Bangsbo test does not give a good estimate of VO2MAX in young soccer players.
PMCID: PMC1724764  PMID: 15039258
20.  Long-term glycine propionyl-l-carnitine supplemention and paradoxical effects on repeated anaerobic sprint performance 
It has been demonstrated that acute GPLC supplementation produces enhanced anaerobic work capacity with reduced lactate production in resistance trained males. However, it is not known what effects chronic GPLC supplementation has on anaerobic performances or lactate clearance.
The purpose of this study was to examine the long-term effects of different dosages of GPLC supplementation on repeated high intensity stationary cycle sprint performance.
Forty-five resistance trained men participated in a double-blind, controlled research study. All subjects completed two testing sessions, seven days apart, 90 minutes following oral ingestion of either 4.5 grams GPLC or 4.5 grams cellulose (PL), in randomized order. The exercise testing protocol consisted of five 10-second Wingate cycle sprints separated by 1-minute active recovery periods. Following completion of the second test session, the 45 subjects were randomly assigned to receive 1.5 g, 3.0 g, or 4.5 g GPLC per day for a 28 day period. Subjects completed a third test session following the four weeks of GPLC supplementation using the same testing protocol. Values of peak power (PP), mean power (MP) and percent decrement of power (DEC) were determined per bout and standardized relative to body mass. Heart rate (HR) and blood lactate (LAC) were measured prior to, during and following the five sprint bouts.
There were no significant effects of condition or significant interaction effects detected for PP and MP. However, results indicated that sprint bouts three, four and five produced 2 - 5% lower values of PP and 3 - 7% lower values of MP with GPLC at 3.0 or 4.5 g per day as compared to baseline values. Conversely, 1.5 g GPLC produced 3 - 6% higher values of PP and 2 -5% higher values of MP compared with PL baseline values. Values of DEC were significantly greater (15-20%) greater across the five sprint bouts with 3.0 g or 4.5 g GPLC, but the 1.5 g GPLC supplementation produced DEC values -5%, -3%, +4%, +5%, and +2% different from the baseline PL values. The 1.5 g group displayed a statistically significant 24% reduction in net lactate accumulation per unit power output (p < 0.05).
The effects of GPLC supplementation on anaerobic work capacity and lactate accumulation appear to be dosage dependent. Four weeks of GPLC supplementation at 3.0 and 4.5 g/day resulted in reduced mean values of power output with greater rates of DEC compared with baseline while 1.5 g/day produced higher mean values of MP and PP with modest increases of DEC. Supplementation of 1.5 g/day also produced a significantly lower rate of lactate accumulation per unit power output compared with 3.0 and 4.5 g/day. In conclusion, GPLC appears to be a useful dietary supplement to enhance anaerobic work capacity and potentially sport performance, but apparently the dosage must be determined specific to the intensity and duration of exercise.
PMCID: PMC2984406  PMID: 20979659
21.  Post-prandial carbohydrate ingestion during 1-h of moderate-intensity, intermittent cycling does not improve mood, perceived exertion, or subsequent power output in recreationally-active exercisers 
This study compared the effects of ingesting water (W), a flavored carbohydrate-electrolyte (CE) or a flavored non-caloric electrolyte (NCE) beverage on mood, ratings of perceived exertion (RPE), and sprint power during cycling in recreational exercisers.
Men (n = 23) and women (n = 13) consumed a 24–h standardized diet and reported 2–4 h post-prandial for all test sessions. After a familiarization session, participants completed 50 min of stationary cycling in a warm environment (wet bulb globe temperature = 25.0°C) at ~ 60-65% of heart rate reserve (146 ± 4 bpm) interspersed with 5 rest periods of 2 min each. During exercise, participants consumed W, CE, or NCE, served in a counterbalanced cross-over design. Beverage volume was served in 3 aliquots equaling each individual’s sweat losses (mean 847 ± 368 mL) during the familiarization session. Profiles of Mood States questionnaires (POMS) were administered and blood glucose levels were determined pre- and post- sub-maximal cycling. Following sub-maximal exercise, participants completed 3 30–s Wingate anaerobic tests (WAnT) with 2.5 min rest between tests to assess performance.
Blood glucose was higher (p <  0.05) after 50 min of submaximal cycling just prior to the WAnT for CE (6.1 ± 1.7 mmol/L) compared to W (4.9 ± 1.5 mmol/L) and NCE (4.6 ± 1.2 mmol/L). Nonetheless, there were no differences among treatments in peak (642 ± 153, 635 ± 143, 650 ± 141 watts for W, NCE, and CE, respectively; p  =  0.44) or mean (455 ± 100, 458 ± 95, 454 ± 95 watts for W, NCE, and CE, respectively; p = 0.62) power for the first WAnT or mean (414 ± 92, 425 ± 85, 423 ± 82 watts, respectively; p = 0.13) power output averaged across all 3 WAnT. Likewise, RPE during submaximal exercise, session RPE, and fatigue and vigor assessed by POMS did not differ among beverage treatments (p > 0.05).
Carbohydrate ingestion consumed by recreational exercisers during a 1–h, moderate-intensity aerobic workout did not alter mood or perceived exertion, nor did it affect subsequent anaerobic performance under the conditions of this study. Drinking caloric sport beverages does not benefit recreational exercisers in a non-fasted state.
PMCID: PMC3562170  PMID: 23347391
Recreational exercise; Non-caloric; Sport beverage; RPE; POMS; Pre-exercise meal
22.  Reliability of the Woodway CurveTM Non-Motorized Treadmill for Assessing Anaerobic Performance 
A curved treadmill offers a practical method of assessing anaerobic power by enabling unrestricted running motion and greater sport specificity. The purpose of this research was to determine reliability of a curved treadmill (cTM) sprint test and to compare performance measures to the traditional Wingate anaerobic power test (WAnT) performed on a cycle ergometer. Thirty-two recreationally active men and women (22.4 ± 2.8 yrs; 1.73 ± 0.08 m; 74. 2 ± 13.2 kg) performed four familiarization trials on cTM, followed by two randomly assigned experimental trials consisting of one 30-second maximum effort on either cTM or WAnT. Each trial was separated by at least 48 hours. Repeated measures analysis of variance (ANOVA), interclass correlations (ICC), standard error of measurement (SEM), and minimal differences (MD) were used to determine reliability of familiarization trials on cTM, and Pearson product moment correlations were calculated to compare cTM and WAnT. ANOVA results showed significant differences (p < 0.05) during the four familiarization trials. Post hoc analysis showed significant differences (p < 0. 05) between the first two trials. Familiarization trials 3 and 4 showed a high reliability for each performance variable (distance: ICC2,1 = 0.969, %SEM = 2.645, p = 0.157; mean velocity: ICC2,1 = 0. 969, %SEM = 2.622, p = 0.173; peak velocity: ICC2,1 = 0.966, %SEM = 3.142, p = 0.033; mean power: ICC2,1 = 0.940, %SEM = 4.140, p = 0.093; and peak power: ICC2,1 = 0.887, %SEM = 11.244, p = 0.669). Participants elicited an average peak power of 1050.4 ± 338.5 Watts on cTM and 1031.4 ± 349.8 Watts on WAnT. Pearson product moment coefficients indicated high correlations between peak power, mean power, and peak velocity (r = 0.75, p < 0.001; r = 0.84, p < 0.001; and r = 0.76, p < 0. 001, respectively) derived from cTM and WAnT. In conclusion, results suggest that after two familiarization trials, cTM is a reliable sprint test for recreationally active men and women. In addition, there are strong relationships between cTM and WAnT in assessing anaerobic performance.
Key pointsThe Woodway Curve 3.0TM is a non-motorized treadmill utilizing a curved platform which allows individuals to simulate an unrestricted sprint test in a laboratory setting, offering a practical and sport specific method of assessing anaerobic power.The curved treadmill provides a reliable sprint test for recreationally active men and women.There are strong relationships between the curved treadmill and cycle ergometer in assessing anaerobic performance.
PMCID: PMC3761752  PMID: 24149732
Anaerobic capacity; power; Wingate anaerobic power test; sprint speed
23.  Effects of Small-Sided Games on Physical Conditioning and Performance in Young Soccer Players 
The purpose of this study was to examine, first, the movement actions performed during two different small-sided games and, second, their effects on a series of field endurance and technical tests. Thirty-four young soccer players (age: 13 ± 0.9 yrs; body mass: 62.3 ± 15.1 kg; height: 1.65 ± 0.06 m) participated in the study. Small-sided games included three-a-side (3 versus 3 players) and six-a-side (6 versus 6 players) games consisting of 10 bouts of 4 min duration with 3 min active recovery between bouts. Soccer player performance was evaluated using five field tests: a) 30m sprint, b) throw-in for distance, c) Illinois Agility Test, d) dribbling the ball and e) horizontal jump before, in the middle and after the implementation of both game situations. Heart rate was monitored during the entire testing session. Each game was also filmed to measure soccer movements within the game. The ANOVA analysis indicated that the three-a- side games displayed significantly higher heart rate values compared with the six-a-side games (p < 0.05). The number of short passes, kicks, tackles, dribbles and scoring goals were significantly higher during the three-a-side compared with the six-a-side game condition (p < 0. 05) while players performed more long passes and headed the ball more often during the six-a-side (p < 0.05). After the three-a-side games, there was a significant decline in sprint and agility performance (p < 0.05), while after both game conditions significant alterations in the throw-in and the horizontal jump performance were observed (p < 0.05). The results of the present study indicated that three-a-side games provide higher stimulus for physical conditioning and technical improvement than six-a-side games and their use for training young soccer players is recommended.
Key pointsThree-a-side games display higher HR compared with six-a-side games.In the three-a-side games players performed more short passes, kicks, dribbles, tackles and scored more goals compared with the six-a-side games.Impairment in endurance and field test performance was observed mainly after three-a-side games.The use of the three-a-side games to develop physical fitness and technique in young soccer players is recommended.
PMCID: PMC3763282  PMID: 24150000
Soccer; small-sided games; field tests; technical actions; intermittent exercise
24.  Effects of 28 days of beta-alanine and creatine supplementation on muscle carnosine, body composition and exercise performance in recreationally active females 
The purpose of this study was to examine the short-term and chronic effects of β-ALA supplementation with and without creatine monohydrate on body composition, aerobic and anaerobic exercise performance, and muscle carnosine and creatine levels in college-aged recreationally active females.
Thirty-two females were randomized in a double-blind, placebo-controlled manner into one of four supplementation groups: β-ALA only (BA, n = 8), creatine only (CRE, n = 8), β-ALA and creatine combined (BAC, n = 9) and placebo (PLA, n = 7). Participants supplemented for four weeks included a loading phase for the creatine for week 1 of 0.3 g/kg of body weight and a maintenance phase for weeks 2–4 of 0.1 g/kg of body weight, with or without a continuous dose of β-ALA of 0.1 g/kg of body weight with doses rounded to the nearest 800 mg capsule providing an average of 6.1 ± 0.7 g/day of β-ALA. Participants reported for testing at baseline, day 7 and day 28. Testing sessions consisted of obtaining a resting muscle biopsy of the vastus lateralis, body composition measurements, performing a graded exercise test on the cycle ergometer for VO2peak with lactate threshold determination, and multiple Wingate anaerobic capacity tests.
Although mean changes were consistent with prior studies and large effect sizes were noted, no significant differences were observed among groups in changes in muscle carnosine levels (BA 35.3 ± 45; BAC 42.5 ± 99; CRE 0.72 ± 27; PLA 13.9 ± 44%, p = 0.59). Similarly, although changes in muscle phosphagen levels after one week of supplementation were consistent with prior reports and large effect sizes were seen, no statistically significant effects were observed among groups in changes in muscle phosphagen levels and the impact of CRE supplementation appeared to diminish during the maintenance phase. Additionally, significant time × group × Wingate interactions were observed among groups for repeated sprint peak power normalized to bodyweight (p = 0.02) and rate of fatigue (p = 0.04).
Results of the present study did not reveal any consistent additive benefits of BA and CRE supplementation in recreationally active women.
PMCID: PMC4263036  PMID: 25505854
Biology of sport  2013;30(3):189-194.
Sustained aerobic exercise not only affects the rate of force development but also decreases peak power development. The aim of this study was to investigate whether anaerobic power of amateur mountain bikers changes during the first half of the competition season. Eight trained cyclists (mean ± SE: age: 22.0 ±0.5 years; height: 174.6 ± 0.9 cm; weight: 70.7 ± 2.6 kg) were subjected to an ergocycle incremental exercise test and to the Wingate test on two occasions: before, and in the middle of the season. After the incremental exercise test the excess post-exercise oxygen consumption was measured during 5-min recovery. Blood lactate concentration was measured in the 4th min after the Wingate test. Maximum oxygen uptake increased from 60.0 ± 1.5 ml min-1 kg-1 at the beginning of the season to 65.2 ± 1.4 ml min-1 kg-1 (P < 0.05) in the season. Neither of the mechanical variables of the Wingate test nor excess post-exercise oxygen consumption values were significantly different in these two measurements. However, blood lactate concentration was significantly higher (P < 0.001) in season (11.0 ± 0.5 mM) than before the season (8.6 ± 0.4 mM). It is concluded that: 1) despite the increase of cyclists’ maximum oxygen uptake during the competition season their anaerobic power did not change; 2) blood lactate concentration measured at the 4th min after the Wingate test does not properly reflect training-induced changes in energy metabolism.
PMCID: PMC3944565  PMID: 24744487
anaerobic power; concurrent training; lactate; competition season; mountain biking

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