Showing papers in "International Journal of Sports Medicine in 2009"
TL;DR: The results of the present study indicate that high intensity activity in elite soccer match-play is influenced by both playing position and previous activity in the game, and these activity patterns are also dependant upon success of the team.
Abstract: The aim of the present investigation was to provide a detailed analysis of the high intensity running activity completed by elite soccer players during match-play A further aim of the study was to evaluate the importance of high intensity running activity to overall team success Observations on individual match performance measures were undertaken on 563 outfield players (median of 8 games per player; range=1-57) competing in the English Premier League from 2003/2004 to 2005/2006 using a computerised tracking system (Prozone, Leeds, England) High intensity activities selected for analysis included total high intensity running distance (THIR), total sprint distance (TSD) and the number and type of sprints undertaken Total high intensity running distance in possession and without possession of the ball was also analysed The THIR was dependant upon playing position with wide midfield (1,049+/-106 m) and central defenders (681+/-128 m) completing the highest and lowest distance respectively (p<0001) High intensity activity was also related to team success with teams finishing in the bottom five (919+/-128 m) and middle ten (917+/-143 m) league positions completing significantly more THIR compared with teams in the top five (885+/-113 m) (p=0003) The THIR and TSD also significantly declined during the 2nd half with the greatest decrements observed in wide midfield and attacking players (p<005) Both positional differences in high intensity activity and the observed change in activity throughout the game were also influenced by team success (p<005) The results of the present study indicate that high intensity activity in elite soccer match-play is influenced by both playing position and previous activity in the game These activity patterns are also dependant upon success of the team This may indicate that overall technical and tactical effectiveness of the team rather than high levels of physical performance per se are more important in determining success in soccer
716 citations
TL;DR: Regular physical activity over longer time is strongly associated with a reduction in all-cause mortality in active subjects compared to sedentary persons and this association was similar and significant in older subjects.
Abstract: In a meta-analysis we investigated the effect of physical activity with different intensity categories on all-cause mortality. Many studies have reported positive effects of regular physical activity on primary prevention. This recent meta-analysis analyzed all-cause mortality with special reference to intensity categories. A computerized systematic literature search was performed in EMBASE, PUBMED, and MEDLINE data bases (1990-2006) for prospective cohort studies on physical leisure activity. Thirty-eight studies were identified and evaluated. The presentation refers to studies with 3 or 4 different intensities of regular physical activity according to a standard questionnaire. There was a significant association of lower all-cause mortality for active individuals compared with sedentary persons. For studies with three activity categories (mildly, moderately, and highly active) and multivariate-adjusted models, highly active men had a 22% lower risk of all-cause mortality (RR=0.78; 95% CI: 0.72 to 0.84) compared to mildly active men. For women, the relative risk was 0.69 (95% CI: 0.53 to 0.90). We observed similar results in moderately active persons compared to mildly active individuals (RR=0.81 for men and RR=0.76 for women). This association of activity to all-cause mortality was similar and significant in older subjects. Regular physical activity over longer time is strongly associated with a reduction in all-cause mortality in active subjects compared to sedentary persons. There is a dose-response curve especially from sedentary subjects to those with mild and moderate exercise with only a minor additional reduction with further increase in activity level.
471 citations
351 citations
TL;DR: The results show that both types of training are equally effective at improving pre-season YYIRTL1 performance, despite GTG being perceived to be more intense.
Abstract: The aim of this study was to compare 7 weeks of soccer-specific small-sided game (SSG) and mixed generic fitness training, on selected physiological, perceptual and performance variables. Twenty-five elite youth players were randomly allocated to either a SSG (coach selected) or generic training group (GTG), in a randomised, parallel matched-group design. In addition to normal training, each group completed two fitness training sessions per week of equal duration. Players completed a V O (2 max) treadmill test, Multistage Fitness Test (MSFT), Yo-Yo Intermittent Recovery Test Level 1 (YYIRTL1), 12x20 m test of repeated-sprint ability (RSA) and 20-m sprint test pre and post training. Training heart rate, perceived training intensity and perceptual fatigue measures were recorded throughout the training period. There were no differences in training heart rate or perceptual well-being measures. However, the GTG did perceive their training to be more intense than SSG. There were no changes in either group for V O (2 max), MSFT, RSA or sprint performance. However, there were improvements in YYIRTL1 performance for both groups over time, but not between groups. The results show that both types of training are equally effective at improving pre-season YYIRTL1 performance, despite GTG being perceived to be more intense.
256 citations
TL;DR: Both HIT and HBT were found to be effective training modes for adolescent handball players, however, HBT should be considered as the preferred training method due to its higher game-based specificity.
Abstract: This study compared the effect of high-intensity interval training (HIT) versus specific game-based handball training (HBT) on handball performance parameters. Thirty-two highly-trained adolescents (15.5+/-0.9 y) were assigned to either HIT (n=17) or HBT (n=15) groups, that performed either HIT or HBT twice per week for 10 weeks. The HIT consisted of 12-24 x 15 s runs at 95% of the speed reached at the end of the 30-15 Intermittent Fitness Test (V(IFT)) interspersed with 15 s passive recovery, while the HBT consisted of small-sided handball games performed over a similar time period. Before and after training, performance was assessed with a counter movement jump (CMJ), 10 m sprint time (10 m), best (RSAbest) and mean (RSAmean) times on a repeated sprint ability (RSA) test, the V(IFT) and the intermittent endurance index (iEI). After training, RSAbest (-3.5+/-2.7%), RSAmean (-3.9+/-2.2%) and V(IFT) (+6.3+/-5.2%) were improved (P<0.05), but there was no difference between groups. In conclusion, both HIT and HBT were found to be effective training modes for adolescent handball players. However, HBT should be considered as the preferred training method due to its higher game-based specificity.
189 citations
TL;DR: It is concluded that the ACTN3 R allele is associated with top-level sprint performance and the X allele and XX genotypes may not be critical but rather additive to endurance performance.
Abstract: Corrigendum / Erratum / Correction to: ACTN3 R577X Polymorphism and Israeli Top-level Athletes ---- Int J Sports Med 2009; 30(09): 695-698 DOI: 10.1055/s-0029-1220731
178 citations
TL;DR: It is revealed that the SAFT(90) produced time dependent impairments in sprinting performance and kinematics of technique which may result from shorter hamstring muscle length, which may have implications for the increased predisposition to hamstring strain injury during the latter stages of soccer match-play.
Abstract: The aim of this study was to investigate the effect of a multi-directional soccer-specific fatigue protocol on sprinting kinematics in relation to hamstring injury risk. Nine semi-professional soccer players (Mean +/- SD: Age: 21.3 +/- 2.9 year; Height 185.0 +/- 8.7 cm; Body Mass 81.6 +/- 6.7 kg) completed the SAFT(90); a multi-directional, intermittent 90 min exercise protocol representative of soccer match-play. The 10m sprint times and three-dimensional kinematic data were recorded using a high-speed motion capture system (Qualisys Track Manager) every 15 min during the SAFT(90). A significant time dependent increase was observed in sprint time during the SAFT(90) (P<0.01) with a corresponding significant decrease in stride length (P<0.01). Analysis of the kinematic sprint data revealed significantly reduced combined maximal hip flexion and knee extension angle, indicating reduced hamstring length, between pre-exercise and half-time (P<0.01) and pre-exercise and full-time (P<0.05). These findings revealed that the SAFT(90) produced time dependent impairments in sprinting performance and kinematics of technique which may result from shorter hamstring muscle length. Alterations in sprinting technique may have implications for the increased predisposition to hamstring strain injury during the latter stages of soccer match-play.
160 citations
TL;DR: It is indicated that the 6MWT is highly reproducible in obese subjects and could thus be used as a fitness indicator in clinical studies and clinical care in this population.
Abstract: The six-minute walk test (6MWT) is an inexpensive, quick and safe tool to evaluate the functional capacity of patients with heart failure and chronic obstructive pulmonary disease. The aim of this study was to determine the reproducibility of the 6MWT in overweight and obese individuals. We thus undertook a prospective repeated-measure validity study taking place in our academic weight management outpatient clinic. The 6MWT was conducted twice the same day in 21 overweight or obese adult subjects (15 females and 6 males). Repeatability of walking distance was the primary outcome. Anthropometric measures, blood pressure and heart rate were also recorded. Participant's mean BMI was 37.2+/-9.8 kg/m(2) (range: 27.0-62.3 kg/m(2)). Walking distance in the morning (mean=452+/-90 m) and in the afternoon (mean=458+/-97 m) were highly correlated (r=0.948; 95% Confidence Interval 0.877-0.978; p<0.001). Walking distance was negatively correlated with BMI (r=-0.47, p=0.03), waist circumference (r=-0.43, p=0.05) and pre-test heart rate (r=-0.54, p=0.01). Our findings indicate that the 6MWT is highly reproducible in obese subjects and could thus be used as a fitness indicator in clinical studies and clinical care in this population.
144 citations
TL;DR: The observed decrement in rapid muscle force capacity is likely to have negative impact on performance in explosive playing actions (i.e. accelerations, kicking, sprinting) that typically is involved in soccer match play.
Abstract: The present study examined the fatigue development in muscle mechanical properties with emphasis on rapid force characteristics and neuromuscular activity in response to high level soccer match play. Young elite soccer players (n=9) were tested before (CON) and after (POST) a soccer match for maximal knee extensor and flexor isometric strength (MVC) and contractile rate of force development (RFD) with synchronous surface electromyography (EMG) recording. Furthermore, maximal vertical jump power and related parameters were assessed. Isometric knee extensor and flexor MVC decreased approximately 10% (p< or =0.01) along with a right-shift in the moment-time curve. RFD decreased approximately 9% (0-200 ms) for the knee flexors while there was a tendency towards reduced RFD during knee extension following soccer match play. Similar reductions were observed for some but not all selected EMG parameters during the MVC and RFD tests. Mechanical jump parameters generally remained unchanged post match play. This study is the first to examine the fatigue induced changes in rapid muscle force production (RFD) induced by soccer match play. The observed decrement in rapid muscle force capacity is likely to have negative impact on performance in explosive playing actions (i.e. accelerations, kicking, sprinting) that typically is involved in soccer match play.
136 citations
TL;DR: The criterion-related validity of the SRT and the modified sit-and-reach test for estimating hamstring flexibility is weak and the present data do not support that the MSRT is a more valid method than the S RT in children and adolescents.
Abstract: The purpose of the present study was to examine the criterion-related validity of the sit-and-reach test (SRT) and the modified sit-and-reach test (MSRT) for estimating hamstring flexibility in children and adolescents as well as to determine whether the MSRT is more valid than the SRT. A total of 87 (45 boys and 42 girls) children (6-12 years old) and adolescents (13-17 years old) performed the SRT and the MSRT. Hamstring flexibility was measured with goniometry through the passive straight-leg raise test. Regression analysis was performed to study the association of SRT and MSRT with hamstring flexibility (criterion measure). The SRT was associated with hamstring flexibility in both children (beta=1.089, R (2)=0.281, p=0.001) and adolescents (beta=0.690, R (2)=0.333, p=0.004). The MSRT was also associated with hamstring flexibility in both children (beta=1.296, R (2)=0.298, p<0.001) and adolescents (beta=0.588, R (2)=0.243, p=0.027). It is concluded that the criterion-related validity of the SRT and the MSRT for estimating hamstring flexibility is weak. The present data do not support that the MSRT is a more valid method than the SRT in children and adolescents.
122 citations
TL;DR: Positive training effects were observed for cardiopulmonary and muscle function, with significant increases in peak oxygen uptake and in the one-repetition maximum, and there were no effects of training on body composition, endocrine and immune function, and haematological variables.
Abstract: This systematic review summarizes the research of previous studies that used resistance training in the post-treatment phase of cancer patients with a focus on methodological quality, training methods and physical outcome measures. We found twenty-four studies (10 RCTs, 4 controlled clinical trials and 10 uncontrolled trials) that met all inclusion criteria. The studies were of moderate methodological quality. The majority of studies involved breast cancer patients (54%), followed by prostate cancer patients (13%). Most studies used a combination of resistance and aerobic training, which was mostly supervised. Resistance training involved large muscle groups, with 1-3 sets of 8-12 repetitions. The duration of the resistance training programs varied from 3-24 weeks, with a training frequency of 1-5 sessions per week. The training intensity ranged from 25% to 85% of the one-repetition maximum. Overall, positive training effects were observed for cardiopulmonary and muscle function, with significant increases in peak oxygen uptake (range: 6-39%), and in the one-repetition maximum (range: 11-110%). In general, there were no effects of training on body composition, endocrine and immune function, and haematological variables. No adverse effects of the resistance training were reported. Based upon these results, we recommend to incorporate resistance training in cancer rehabilitation programmes.
TL;DR: The accuracy of the Velotron cycle ergometer and the SRM power meter appears to be dependent on the type of test being performed, as each power monitoring system measures power at various positions, particularly when power is variable.
Abstract: The purpose of this study was to determine the accuracy of the Velotron cycle ergometer and the SRM power meter using a dynamic calibration rig over a range of exercise protocols commonly applied in laboratory settings. These trials included two sustained constant power trials (250 W and 414 W), two incremental power trials and three high-intensity interval power trials. To further compare the two systems, 15 subjects performed three dynamic 30 km performance time trials. The Velotron and SRM displayed accurate measurements of power during both constant power trials (<1% error). However, during high-intensity interval trials the Velotron and SRM were found to be less accurate (3.0%, CI=1.6-4.5% and -2.6%, CI=-3.2--2.0% error, respectively). During the dynamic 30 km time trials, power measured by the Velotron was 3.7+/-1.9% (CI=2.9-4.8%) greater than that measured by the SRM. In conclusion, the accuracy of the Velotron cycle ergometer and the SRM power meter appears to be dependent on the type of test being performed. Furthermore, as each power monitoring system measures power at various positions (i.e. bottom bracket vs. rear wheel), caution should be taken when comparing power across the two systems, particularly when power is variable.
TL;DR: During adolescence dribbling performance can assist in identifying the best players for the future, and the longitudinal results showed that during adolescence the talented players who ultimately became professionals were on average 0.3 s faster on 30m peak dribbled performance and on average 1 second faster on 3 x 30m repeated dribble performance than the players whoUltimately turned amateur.
Abstract: The purpose of this study was to investigate the relationship between the development of the technical skill dribbling during ages 14-18 and adulthood playing level. The results gained insight in the required level of the technical skill dribbling during adolescence to be capable of becoming a professional soccer player. Talented players (n=131), aged 14-18 were measured while they were part of a developmental soccer program, testing took place annually. The players were identified as professional (n=54) or amateur (n=77) later on in their career (age>20). In total 238 measurements of dribbling performance were assessed by means of the Shuttle Dribble Test. A longitudinal model estimated the development for optimal dribbling performance (peak dribbling) and for dribbling performance under fatigue (repeated dribbling), for players ultimately reaching professional status and for players reaching amateur status. The longitudinal results showed that during adolescence the talented players who ultimately became professionals were on average 0.3 s faster on 30m peak dribbling performance and on average 1 second faster on 3 x 30m repeated dribbling performance than the players who ultimately turned amateur (p=0.001). It is concluded that during adolescence dribbling performance can assist in identifying the best players for the future.
TL;DR: In conclusion, a short period of traditional strength training can improve RE in well-trained runners, but this improvement can be dependent on the strength training characteristics.
Abstract: The objective of this study was to compare the effect of different strength training protocols added to endurance training on running economy (RE). Sixteen well-trained runners (27.4 +/- 4.4 years; 62.7 +/- 4.3 kg; 166.1 +/- 5.0 cm), were randomized into two groups: explosive strength training (EST) (n = 9) and heavy weight strength training (HWT) (n = 7) group. They performed the following tests before and after 4 weeks of training: 1) incremental treadmill test to exhaustion to determine of peak oxygen uptake and the velocity corresponding to 3.5 mM of blood lactate concentration; 2) submaximal constant-intensity test to determine RE; 3) maximal countermovement jump test and; 4) one repetition maximal strength test in leg press. After the training period, there was an improvement in RE only in the HWT group (HWT = 47.3 +/- 6.8 vs. 44.3 +/- 4.9 ml . kg (-1) . min (-1); EST = 46.4 +/- 4.1 vs. 45.5 +/- 4.1 ml . kg (-1) . min (-1)). In conclusion, a short period of traditional strength training can improve RE in well-trained runners, but this improvement can be dependent on the strength training characteristics. When comparing to explosive training performed in the same equipment, heavy weight training seems to be more efficient for the improvement of RE.
TL;DR: Results of this study suggest the importance of optimal approach technique to reach a maximal JH in the volleyball SJ, and suggest the SJ movement is influenced by general jumping ability.
Abstract: The purpose of this study was to determine the influence of upper and lower extremity movements on the volleyball spike jump (SJ) and how this movement may differ from the standing vertical jumps due to its asymmetry. The 3-D kinematics of body segments were measured in 16 experienced volleyball players with a VICON motion capture system. The jump heights (JH) of counter-movement (CM) and SJ were determined utilizing a force platform. A significant correlation was found between the JH during the SPJ and the maximal horizontal velocity of the center of mass (CoM) (r=0.71, p=0.002), the minimum height of the CoM (r=-0.68, p=0.004), the JH during CMJ (r=0.66, p=0.006) and SJ (r=0.74, p=0.001), the range of movement of right knee flexion-extension (r=0.76, p=0.001) and the angular velocity of left shoulder hyperextension (r=0.72, p=0.002). The asymmetry of the SJ revealed differences in angles, angular velocities of the right and left legs and arms, and a significant difference (p=0.001) between the distances of the left and right foot center to the CoM. Results of our study suggest the importance of optimal approach technique to reach a maximal JH in the volleyball SJ. The SJ movement is influenced by general jumping ability.
TL;DR: During run-based repeated sprinting, AR was associated with reduced repeated sprint ability and higher muscle deoxygenation during short repeated maximal running.
Abstract: The purpose of this study was to compare the effect of active (AR) versus passive recovery (PR) on muscle deoxygenation during short repeated maximal running. Ten male team sport athletes (26.9+/-3.7y) performed 6 repeated maximal 4-s sprints interspersed with 21 s of either AR (2 m.s (-1)) or PR (standing) on a non-motorized treadmill. Mean running speed (AvSp (mean)), percentage speed decrement (Sp%Dec), oxygen uptake (V O (2)), deoxyhemoglobin (HHb) and blood lactate ([La] (b)) were computed for each recovery condition. Compared to PR, AvSp (mean) was lower (3.79+/-0.28 vs. 4.09+/-0.32m.s (-1); P<0.001) and Sp%Dec higher (7.2+/-3.7 vs. 3.2+/-0.1.3%; P<0.001) for AR. Mean V O (2) (3.64+/-0.44 vs. 2.91+/-0.47L.min (-1), P<0.001), HHb (94.4+/-16.8 vs. 83.4+/-4.8% of HHb during the first sprint, P=0.02) and [La] (b) (13.5+/-2.5 vs. 12.7+/-2.2 mmol.l (-1), P=0.03) were significantly higher during AR compared to PR. In conclusion, during run-based repeated sprinting, AR was associated with reduced repeated sprint ability and higher muscle deoxygenation.
TL;DR: Preliminary data suggest that the implementation of additional fitness training is beneficial for contemporary dance students to achieve a better performance outcome, and whether supplementary exercise interventions, in addition to normal dance training, further improves contemporary dance performance.
Abstract: It has been suggested that dancers are less fit compared to other athletes. However, the majority of studies make their arguments based on data deriving mainly from ballet. Therefore, the aim of the current review was to investigate: a) aerobic and anaerobic fitness, muscular strength and body composition characteristics in contemporary dancers of different levels, and b) whether supplementary exercise interventions, in addition to normal dance training, further improves contemporary dance performance. Three databases (Medline, Cochrane and the Cumulative Index to Nursing & Allied Health research database) were searched to identify publications regarding the main fitness components of contemporary professional and student dancers. At a professional level, it appears that contemporary dancers demonstrate higher maximal oxygen uptake and higher scores in muscular endurance than ballet dancers. However, contemporary dance students are equally fit compared to their ballet counterparts and their body composition is also very similar. Only two studies have investigated the effects of supplementary exercise training on aspects of dance performance. Further research is needed in order to confirm preliminary data, which suggest that the implementation of additional fitness training is beneficial for contemporary dance students to achieve a better performance outcome.
TL;DR: Ten weeks of PT induced musclehypertrophy of the upper and lower limb muscles in older men may yield better results in muscle hypertrophy when compared with TRT, according to the results.
Abstract: The present study aimed at comparing the effects of traditional resistance training (TRT) and power training (PT) in inducing muscle hypertrophy in older men. Twenty older men (aged between 69 and 76 years) were divided in two groups: TRT training (n=9) and PT training (n=11). The volunteers trained twice a week, during 10 weeks. Both groups performed an equal work output and the same exercises with loads between 40% and 60% of 1 RM. Three sets of eight repetitions of each exercise were performed with rest intervals of 90 s between sets. Muscle thickness was measured by ultrasound at the biceps brachii (BIC) and rectus femoris (RF), using a 12 MHz high resolution scanning probe. An ANCOVA was used to compare post training muscle thickness values between TRT and PT, using baseline values as covariates. According to the results, RF muscle thickness increased only in PT, while BIC muscle thickness increased in both groups, but with larger increases in PT. In conclusion, ten weeks of PT induced muscle hypertrophy of the upper and lower limb muscles in older men. PT training may yield better results in muscle hypertrophy when compared with TRT.
TL;DR: Compared methods of using skinfold data and an equation for predicting body fat values in professional soccer players to derive an equation incorporating anterior thigh, abdominal, triceps and medial calf sites, demonstrating the lowest bias and highest relationship and agreement with DXA.
Abstract: The use of generic equations for estimating percent body fat from skinfold thicknesses can be criticised when applied to specific sports. The present aims were to compare existing methods of using skinfold data and to derive an equation for predicting body fat values in professional soccer players. Forty-five professional soccer players (24.2 +/- 5.0 years; 82.0 +/- 8.5 kg; 1.82 +/- 0.07 m) participated. Skinfold thicknesses were assessed at eight sites for the application of existing prediction equations. Skinfold data were also utilised to determine a novel soccer-specific equation. All players had a reference estimate of percent fat by dual-energy x-ray absorptiometry (DXA). The existing skinfold equations differed from the DXA-referenced values by varying degrees, the equation of Withers et al. (1987) demonstrating the lowest bias and highest relationship and agreement with DXA. Regression analysis resulted in an equation incorporating anterior thigh, abdominal, triceps and medial calf sites, accounting for 78.4% variance in DXA criterion values.
TL;DR: Findings support use of the supramaximal testing protocol to confirm VO2max attainment in healthy, sedentary men and women completing incremental cycle ergometry.
Abstract: Supramaximal testing is widely used to verify VO2max attainment, yet its efficacy in sedentary subjects is unknown The aim of the study was to test this hypothesis in men and women completing maximal cycle ergometry Fifteen sedentary subjects (age=224+/-39 year) completed incremental exercise, and returned at least 24 h later to complete constant load exercise at 105% peak work rate (Wmax) Another group of nine sedentary men and women (age=218+/-5 year) completed supramaximal exercise at 115% Wmax 1-15 h after incremental exercise During exercise, gas exchange data and heart rate (HR) were continuously obtained VO2max was similar (p>005) between incremental and supramaximal exercise in subjects in the first (3232+/-481 mL/kg/min vs 3180+/-535 mL/kg/min) and second subset (4063+/-361 mL/kg/min vs 4166+/-555 mL/kg/min) Maximal HR was lower (p<005) with supramaximal exercise, yet respiratory exchange ratio was higher (p<005) Test-retest reliability (r=081-089, p<005) for VO2max was high during repeated bouts of supramaximal testing Findings support use of this protocol to confirm VO2max attainment in healthy, sedentary men and women completing incremental cycle ergometry
TL;DR: Final treadmill velocity in an VO2max test is the single best predictor of 5000-m performance in untrained and trained states, and stepwise regression analysis showed that only velocity at lactate threshold significantly improved the accuracy of prediction provided by final treadmill velocity alone.
Abstract: In this study, we aimed to investigate physiological determinants of endurance performance that best predict 5000-m average run velocity before and after endurance training. Thirty-nine previously untrained participants completed a 5000-m run; a constant velocity test (measuring running economy); and an incremental treadmill test to determine maximal oxygen uptake, final treadmill velocity, and velocity and oxygen uptake at lactate threshold, before and after six weeks of endurance training. Maximal oxygen uptake, final treadmill velocity, and velocity and oxygen uptake at threshold all increased significantly after training (p < 0.05). Average velocity for 5000 m increased significantly (p < 0.05). Running economy was not significantly altered. Correlation analysis revealed final treadmill velocity was most strongly related to 5000-m performance, in both untrained and trained states (r = 0.89, 0.83). Lactate threshold velocity (r = 0.73, 0.76), maximal oxygen uptake (r = 0.55, 0.51) and oxygen uptake at threshold (r = 0.45, 0.45) also showed significant correlations. In contrast, running economy was not significantly related to performance. These results demonstrate that final treadmill velocity in an VO2max test is the single best predictor of 5000-m performance in untrained and trained states. Furthermore, stepwise regression analysis showed that only velocity at lactate threshold significantly improved the accuracy of prediction provided by final treadmill velocity alone.
TL;DR: The main findings are that there are virtually no relevant running time differences in marathon finishers from 20 to 55 years and the majority of middle-aged and elderly athletes have training histories of less than seven years of running.
Abstract: Successful finishing of marathon requires regular endurance training and appropriate lifestyle. Thus, marathon running times and training data from large samples of physically active and fit elderly are ideal for the assessment of age-related performance. In the present study we analyzed 439 278 running times from result lists of 108 marathon competitions and data from a survey via internet questionnaire about training and behavioural factors of marathon finishers. Marathon times and 6 992 data sets from the internet questionnaire were separated into groups based on age and sex and analyzed by two-way ANOVA. Our main findings are that 1) there are virtually no relevant running time differences (p 0.01). The present findings strengthen the concept that considers aging as a biological process that can be considerably speeded up or slowed down by multiple lifestyle related factors.
TL;DR: Clinicians should consider the magnitude of muscle activation and activation ratios when prescribing hamstring and quadriceps exercises as well as the RMS EMG of the BF to RF and BF to VL activation ratios between exercises.
Abstract: This study evaluated the biceps femoris (BF), rectus femoris (RF), and vastus lateralis (VL) activation and activation ratios of a variety of resistance training exercises characterized by knee extension, and determined if subject strength or gender affects these variables. The exercises evaluated included the leg extension, squat, deadlift, lunge, and step up. Subjects included 20 athletes and recreationally active college students. Electromyography (EMG) of the muscles expressed as a percentage of maximum voluntary isometric contraction (MVIC), as well as the BF to RF and BF to VL EMG ratio, were determined for each exercise. There was no significant interaction between gender and exercise type for the RMS EMG of the BF (p = 0.67), RF (p = 0.53), or VL (p = 0.06). Main effects were found for the RMS EMG of the BF (p = 0.00), RF (p = 0.00), and VL (p = 0.00), as well as the RMS EMG of the BF to RF activation ratio (p = 0.00) and BF to VL activation ratios (p = 0.003), between exercises. Peak RMS EMG was also assessed. Post hoc analysis identified specific differences in muscle activation and ratios between exercises. Clinicians should consider the magnitude of muscle activation and activation ratios when prescribing hamstring and quadriceps exercises.
TL;DR: Exercise duration and intensity are essential factors in eliciting cTnT release interactively following an endurance exercise, and exercise intensity compared to duration appears to cause a more pronounced increase in cTNT levels.
Abstract: The purpose of this study was to evaluate the interactive effects of exercise duration and intensity on the elevation of serum cardiac troponin T (cTnT) in trained adolescent athletes following prolonged exercise in a laboratory-based setting. Thirteen male adolescent runners (mean age 14.8+/-1.6 year) performed two 45-min and two 90-min constant-load treadmill runs with intensities set at the running speeds that corresponded to either 80% or 100% ventilatory threshold (Th(vent)): 80%Th(vent)45 min, 80%Th(vent)90 min, 100%Th(vent)45 min and 100%Th(vent)90 min. Serum cTnT was assessed pre and post exercise. In the 100%Th(vent)45 min trial, the post-exercise serum cTnT level [(Median) 0.015 ng x ml(-1); (Range)<0.01-0.375 ng x ml(-1)] was greater than that of the 80%Th(vent)45 min (undetectable cTnT) and 80%Th(vent)90 min (detectable cTnT in two subjects, 0.021 and 0.133 ng x ml(-1)) trials (P<0.01). The serum cTnT level was further increased in the 100%Th(vent)90 min trial [(Median) 0.063 ng x ml(-1); (Range)<0.01-0.417 ng x ml(-1)] when the treadmill run was sustained for an additional 45 min (P<0.05). Similar changes were observed in the cTnT positive rate in subjects. These findings suggest that exercise duration and intensity are essential factors in eliciting cTnT release interactively following an endurance exercise. Nevertheless, exercise intensity compared to duration appears to cause a more pronounced increase in cTnT levels.
TL;DR: Moderate resistance training programs can improve muscle function without injuries and can be a promising therapy to delay the functional deterioration in multiple sclerosis patients.
Abstract: This study examined the effects of an eight-week progressive resistance training on different strength manifestations, muscle mass and functionality in multiple sclerosis patients. Thirteen volunteered patients (average age 43 years; range 35-51) with a confirmed diagnosis by a neurologist and mild to moderate disability participated twice a week in an eight-week progressive resistance training program after an eight-week control period without training. Intensity ranged from 40-70% of their maximal voluntary contraction. Outcome assessments included magnetic resonance image of the right and left thighs, strength manifestations (maximal voluntary contraction, muscular endurance and power), and functionality by the Up and Go test. All outcome assessments remained unaltered during the eight-week control period. After the eight-week strength training period, isometric strength (+16%, p<0.01), muscular endurance (+84%; p<0.001), maximal power (+51%, p<0.001), muscular hypertrophy from slice 6/27 to slice 11/27 of both thighs (p<0.05), and functionality (p<0.001) improved significantly. Moderate resistance training programs can improve muscle function without injuries and can be a promising therapy to delay the functional deterioration in multiple sclerosis patients.
TL;DR: The notion that similar changes are observable in the EMG signal pre- and post-training at fatigue when exercising with the same relative load supports the notion that the muscle is relatively able to work more and accumulate more metabolites before task failure.
Abstract: This study examined the effects of heavy resistance training on dynamic exercise-induced fatigue task (5 x 10RM leg-press) after two loading protocols with the same relative intensity (%) (5 x 10RM(Rel)) and the same absolute load (kg) (5 x 10RM(Abs)) as in pretraining in men (n=12). Maximal strength and muscle power, surface EMG changes [amplitude and spectral indices of muscle fatigue], and metabolic responses (i.e.blood lactate and ammonia concentrations) were measured before and after exercise. After training, when the relative intensity of the fatiguing dynamic protocol was kept the same, the magnitude of exercise-induced loss in maximal strength was greater than that observed before training. The peak power lost after 5 x 10RM(Rel) (58-62%, pre-post training) was greater than the corresponding exercise-induced decline observed in isometric strength (12-17%). Similar neural adjustments, but higher accumulated fatigue and metabolic demand were observed after 5 x 10RM(Rel). This study therefore supports the notion that similar changes are observable in the EMG signal pre- and post-training at fatigue when exercising with the same relative load. However, after training the muscle is relatively able to work more and accumulate more metabolites before task failure. This result may indicate that rate of fatigue development (i.e. power and MVC) was faster and more profound after training despite using the same relative intensity.
TL;DR: In world-class cyclists, a significant genotype effect with no concomitant covariate effect for ACTN3 is found, with cyclists who were not alpha-actinin-3 deficient (RR + RX genotypes) having higher PPO and VT values than their XX counterparts.
Abstract: We assessed the possible association between variants of the genes encoding for the angiotensin-converting enzyme ( ACE) and alpha-actinin-3 ( ACTN3) (both individually and combined) and several endurance phenotypic traits, eg, peak power output (PPO), ventilatory (VT) and respiratory compensation threshold (RCT), among others, in professional road cyclists and sedentary controls (n = 46 each) We applied an ANCOVA test using the aforementioned phenotype traits as dependent variables, ACE and/or ACTN3 genotype as the fixed (independent) factor and age and body mass as covariates We only found a significant genotype effect with no concomitant covariate effect for ACTN3, with cyclists who were not alpha-actinin-3 deficient (RR + RX genotypes) having higher PPO and VT values than their XX counterparts (mean [SEM]: 74 (01) vs 71 (01) W/kg, p = 0035; and 45 (01) vs 43 (01) W/kg, p = 0029, respectively) Cyclists with an "extreme" ACTN3 and ACE genotype combination, ie, most strength/power oriented (DD + RR/RX), had higher RCT values than those with the "intermediate" combinations (II + RX/RR, p = 0036; and DD + XX, p = 0004) but similar to those with the most endurance oriented genotype (II + XX) No significant differences (p > 005) were found in controls In summary, in world-class cyclists, we only found an association between ACTN3 genotypes and VT and PPO, and between ACTN3/ACE genotype combinations and RCT
TL;DR: It is concluded that short-term, moderate intensity and low volume endurance training can significantly increase testosterone concentration in previously untrained men.
Abstract: The aim of this study was to investigate the effect of short-term, moderate intensity and low volume endurance training on gonadal hormone profile in untrained men. Fifteen young, healthy men performed an endurance training of 5-week duration on a cycle ergometer. Before and after the exercise program all participants completed a maximal incremental test. Concentration of testosterone (T), sex hormone-binding globulin (SHBG) and cortisol (C) as well as blood morphology were determined in venous blood samples at rest both before and after the training. The training program resulted in 3.7% improvement of maximal oxygen uptake (VO(2max)) and 8.2% improvement of power output reached at VO(2max) (PO (max)). This was accompanied by significant increase in T (from 18.84+/-5.73 nmol.l(-1) to 22.03+/-6.61 nmol.l(-1), p = 0.0004) and calculated fT concentration (from 374+/-116 pmol.l(-1) to 470+/-153 pmol.l(-1), p = 0.00005). Moreover, the training caused a significant decrease in SHBG concentration (from 34.45+/-11.26 nmol.l(-1) to 31.95+/-10.40 nmol.l(-1), p = 0.01), whereas no significant changes were found in the cortisol concentration (334+/-138 nmol.l(-1) vs. 367+/-135 nmol.l(-1) for pre- and post-training measures, respectively, p = 0.50) and T/C and fT/C ratios. We have concluded that short-term, moderate intensity and low volume endurance training can significantly increase testosterone concentration in previously untrained men.
TL;DR: Increase in strength performance can primarily be explained by an improved neural drive of the agonist muscles and the inconsistent effect of resistance training on postural control may be explaining by heterogeneity of testing methodology or by the incapability of isolated resistance training to improve posturalControl.
Abstract: Age-related processes in the neuromuscular and the somatosensory system are responsible for decreases in maximal and explosive force production capacity and deficits in postural control. Thus, the objectives of this study were to investigate the effects of resistance training on strength performance and on postural control in seniors. Forty healthy seniors (67+/-1 yrs) participated in this study. Subjects were randomly assigned to a resistance training (n=20) and a control group (n=20). Resistance training for the lower extremities lasted for 13 weeks at 80% of the one repetition maximum. Pre and post tests included the measurement of maximal isometric leg extension force with special emphasis on the early part of the force-time-curve and the assessment of static (functional reach test) and dynamic (tandem walk test, platform perturbation) postural control. Resistance training resulted in an enhanced strength performance with increases in explosive force exceeding those in maximal strength. Improved performances in the functional reach and in the tandem walk test were observed. Resistance training did not have an effect on the compensation of platform perturbations. Increases in strength performance can primarily be explained by an improved neural drive of the agonist muscles. The inconsistent effect of resistance training on postural control may be explained by heterogeneity of testing methodology or by the incapability of isolated resistance training to improve postural control.
TL;DR: A single session WBV treatment does not affect the quadriceps stretch reflex in terms of timing or amplitude and two-way ANOVAs detected differences between groups over time.
Abstract: Whole body vibration (WBV) is theorized to enhance neural potentiation of the stretch reflex. The purpose of this study was to determine if WBV affects the quadriceps reflex from a patellar tendon tap. Subjects were 22 volunteers (age 23 +/- 2 yrs, ht 172.8 +/- 10.8 cm, body mass 68.6 +/- 12.3 kg). The stretch reflex was elicited from the dominant leg pre, post, and 30-min post WBV treatment. A matched control group repeated the procedure without WBV. WBV treatment consisted of 5, 1-min bouts at 26 Hz with a 1-min rest period between bouts while maintaining a standardized squatting position. Two-way ANOVAs were used to detect differences between groups over time for vastus medialis (VM) and vastus lateralis (VL) latency, EMG amplitude, electromechanical delay (EMD), and force output. No group x time interactions were detected for latency (VM; F ((2,40)) = 1.20, p = .313: VL; F ((2,40)) = 0.617, p = .544), EMG mean amplitude (VM; F ((2,40)) = 0.169, p = .845: VL; F ((2,40)) = 0.944, p = .398), EMD (VM; F ((2,40)) = 0.715, p = .495: VL; F ((2,40)) = 1.24, p = .301), or quadriceps force (F ((2,40)) = 1.11, p = .341) A single session WBV treatment does not affect the quadriceps stretch reflex in terms of timing or amplitude.