Showing papers in "International Journal of Sports Medicine in 2007"
TL;DR: The paper provides a detailed description of the demands placed on elite soccer players, according to their positional role at different work intensities, which may be helpful in the development of individualized training programs.
Abstract: The paper provides a large-scale study into the motion characteristics of top class soccer players, during match play, according to playing position. Three hundred top-class outfield soccer players were monitored during 20 Spanish Premier League and 10 Champions League games using a computerized match analysis system (Amisco Pro ® , Nice, France). Total distance covered in five selected categories of intensity, and the mean percentage of playing time spent in each activity were analyzed according to playing position. Midfield players covered a significantly greater total distance (p < 0.0001) than the groups of defenders and forwards did. Analyzing the different work rates showed significant differences (p < 0.5 – 0.0001) between the different playing positions. There were no significant differences between halves in the total distance covered, or in distances covered at submaximal and maximal intensities. However, significantly more distance was covered in the first half compared to the second in medium intensities (11.1 – 19 km/h). The current findings provide a detailed description of the demands placed on elite soccer players, according to their positional role at different work intensities, which may be helpful in the development of individualized training programs.
1,072 citations
TL;DR: The main finding was that TD, HIR and VHIR were greater at the end of the season compared to Best opponent teams compared to Worst opponent teams, which may be used to interpret meaningful changes in match performance in top level soccer.
Abstract: This study examined the influence of the opposing team, seasonal variations and the influence of first half activity on match performance in top-level soccer players. Physical performance measures were collected using the ProZone match analysis system from 20 professional soccer players from the same team and their opponents (n = 188) during a season. Match activities (standing, walking, jogging, running, high-speed running and sprinting), distances (total distance [TD], high-intensity running [HIR] and very high-intensity running [VHIR]) and other measures including involvement with the ball and peak running speed were collected. The influence of opponent team, the level of opposition, first half physical activities on second half activities, and playing position were analysed. The main finding was that TD (r = 0.62, p < 0.05), HIR (r = 0.51, p < 0.05), and VHIR (r = 0.65, p < 0.05) of the reference team was influenced by the activity profile of the opponent teams. The TD and HIR was higher against Best opponent teams compared to Worst opponent teams (p < 0.05), and the TD, HIR and VHIR travelled in the first half significantly influenced the distances covered in the second half. TD, HIR and VHIR were greater at the end of the season. These results may be used to interpret meaningful changes in match performance in top level soccer.
752 citations
TL;DR: Empirical support is given to the construct validity of RSA and incremental running tests as measures of match-related physical performance in top-level professional soccer players.
Abstract: The aim of this study was to examine the construct validity of selected field tests as indicators of match-related physical performance. During the competitive season, eighteen professional soccer players (age 26.2 +/- 4.5 yrs, mass 80.8 +/- 7.8 kg, and height 181.9 +/- 3.7 cm) completed an incremental running field test to exhaustion, a vertical-jump and a repeated-sprint ability (RSA) test. Match physical performance was quantified during official matches using a video-computerized, semi-automatic, match analysis image recognition system, (ProZone, Leeds, UK). The selected measures of match physical performance were: total distance covered (TD), high intensity running (HIR: > 14.4 km . h (-1)), very high intensity running (VHIR:> 19.8 km . h (-1)), sprinting (> 25.2 km . h (-1)) and top running speed. Significant correlations were found between peak speed reached during the incremental field test and TD (r = 0.58, R (2) = 0.34; p < 0.05), HIR (r = 0.65, R (2) = 0.42; p < 0.01) and VHIR (r = 0.64, R (2) = 0.41; p < 0.01). Significant correlations were also found between RSA mean time and VHIR (r = - 0.60, R (2) = 0.36; p < 0.01) and sprinting distance (r = - 0.65, R (2) = 0.42; p < 0.01). Significant differences were found between the best and worst group as defined by the median split technique for peak speed (TD = 12 011 +/- 747 m vs. 10 712 +/- 669, HIR = 3192 +/- 482 m vs. 2314 +/- 347 m, and VHIR = 1014 +/- 120 vs. 779 +/- 122 m, respectively; p < 0.05) and RSA mean time (VHIR = 974 +/- 162 m vs. 819 +/- 144 m, and sprinting = 235 +/- 56 vs. 164 +/- 58 m, respectively; p < 0.05). In conclusion, this study gives empirical support to the construct validity of RSA and incremental running tests as measures of match-related physical performance in top-level professional soccer players.
560 citations
TL;DR: It is suggested that muscular strength, power and endurance were reduced following the overload training, indicating a state of overreaching.
Abstract: The purpose of this study was to examine the influence of overreaching on muscle strength, power, endurance and selected biochemical responses in rugby league players. Seven semi-professional rugby league players (.VO(2max) = 56.1 +/- 1.7 mL . kg (-1) . min (-1); age = 25.7 +/- 2.6 yr; BMI = 27.6 +/- 2.0) completed 6 weeks of progressive overload training with limited recovery periods. A short 7-day stepwise reduction taper immediately followed the overload period. Measures of muscular strength, power and endurance and selected biochemical parameters were taken before and after overload training and taper. Multistage fitness test running performance was significantly reduced (12.3 %) following the overload period. Although most other performance measures tended to decrease following the overload period, only peak hamstring torque at 1.05 rad . s (-1) was significantly reduced (p < 0.05). Following the taper, a significant increase in peak hamstring torque and isokinetic work at both slow (1.05 rad . s (-1)) and fast (5.25 rad . s (-1)) movement velocities were observed. Minimum clinically important performance decreases were measured in a multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) following the overload period. Following the taper, minimum clinically important increases in the multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) and 10-m sprint performance were observed. Compared to resting measures, the plasma testosterone to cortisol ratio, plasma glutamate, plasma glutamine to glutamate ratio and plasma creatine kinase activity demonstrated significant changes at the end of the overload training period (p < 0.05). These results suggest that muscular strength, power and endurance were reduced following the overload training, indicating a state of overreaching. The most likely explanation for the decreased performance is increased muscle damage via a decrease in the anabolic-catabolic balance.
256 citations
TL;DR: The present results suggest that none of the physiological and biochemical variables measured in this study were effective for the early identification of overreaching in experienced triathletes, however, the RESTQ-76 Sport questionnaire may provide a practical tool for recognizing over reaching in its early stages.
Abstract: The present investigation compared responses in previously identified physiological, biochemical, and psychological markers of overreaching in triathletes. Sixteen experienced male triathletes (.VO(2max) [mean +/- SD] = 55.7 +/- 4.9 mL . kg (-1) . min (-1), age = 31.3 +/- 11.7 yr) were divided into matched groups according to physical and performance characteristics, and were randomly assigned to either intensified training (IT) or normal training (NT) groups. Physiological, biochemical, and psychological measures were taken at baseline, following four weeks of overload training and following a two-week taper. The IT group completed 290 % greater physical training load than the NT group during the overload period. The subjects completed a 3-km run time trial (3-km RTT) each week in order to assess the time course of change in endurance performance. 3-km RTT performance was significantly reduced (3.7 +/- 7.5 %; p < 0.05) following four weeks of overload training in the IT group confirming a state of overreaching. During the same period, 3-km RTT performance significantly improved in the NT group (3.0 +/- 1.1 %; p < 0.05). Following the two-week taper, 3-km RTT performance significantly improved in the IT group (7.0 +/- 5.6 %; p < 0.05). Hemoglobin concentration significantly decreased and urea increased in both groups during the overload period (p < 0.05). During the taper hemoglobin normalized with a greater increase in the IT group compared to the NT group (p < 0.05). A significant increase in free testosterone to cortisol ratio was also observed in the IT group compared to the NT group during the taper (p < 0.05). No significant changes were observed for any other biochemical variables during the period of investigation. The RESTQ-76 Sport questionnaire showed an impaired recovery-stress state with increased training load, which improved following the taper in the IT group (p < 0.05). These present results suggest that none of the physiological and biochemical variables measured in this study were effective for the early identification of overreaching in experienced triathletes. However, the RESTQ-76 Sport questionnaire may provide a practical tool for recognizing overreaching in its early stages. These findings have implications for monitoring training status in athletes in a practical training setting.
240 citations
TL;DR: It is concluded that the short contact times required in economical and high speed running suggests that fast force production is important for both economical running and high top running speed in distance runners.
Abstract: The main purpose of the present study was to investigate the relationships between running mechanics, top running speed and economy in young endurance athletes. Twenty five endurance athletes (age 19.8 +/- 1.1 years, stature 1.82 +/- 0.07 m and body mass 69.4 +/- 7.5 kg) performed two separate tests on an indoor track. The first test was 8 x 30 m with increasing speed, and the second test was incremental 5 - 6 x 1,000 m. In the first test, ground reaction forces and stride characteristics were measured from each running speed. In the second test, running economy at the speed of 3.89 m . s (-1) and maximal oxygen uptake were determined. Ground contact time was the only factor which correlated significantly with both running economy (r = 0.49, p < 0.05) and maximal running speed (r = - 0.52, p < 0.01). Furthermore, maximal running speed was correlated significantly with the mass-specific horizontal force (r = 0.56, p < 0.01) but not with the vertical effective force. It is concluded that the short contact times required in economical and high speed running suggests that fast force production is important for both economical running and high top running speed in distance runners.
229 citations
TL;DR: This study investigated the influence of CAI on the performance of a dynamic postural control task, the Star Excursion Balance Test (SEBT), after fatiguing activities to investigate the effects of chronic ankle instability and lower extremity fatigue on measures of neuromuscular control.
Abstract: The combined effects of chronic ankle instability (CAI) and lower extremity fatigue on measures of neuromuscular control have not been well established. The purpose of this study was to investigate the influence of CAI on the performance of a dynamic postural control task, the Star Excursion Balance Test (SEBT), after fatiguing activities. Thirty subjects with (n = 14) or without (n = 16) unilateral CAI completed anterior, medial, and posterior reaching directions of the SEBT performed before and after a lunging fatigue protocol and an open chain ankle isokinetic fatigue protocol. Pre-post fatigue change scores were calculated for sagittal plane kinematics of the stance leg and the normalized reach distances (%MAXD). Using a regression model, group and kinematic data were used to explain between subject differences in %MAXD. For each reaching direction, a separate analysis was completed for the two fatigue conditions. When reaching anteriorly after the lunge fatigue condition, CAI and the changes in knee and hip flexion predicted approximately 49 % of the variance in %MAXD (R2 = .487; p = .001). When reaching medially under lunge fatigue, CAI predicted approximately 20 % of the variance in %MAXD (R2 = .198; p = .014). Isolated ankle fatigue did not cause significantly different responses between groups. For two of the reaching directions, CAI status significantly influenced the variances in %MAXD under the influence of lunge fatigue. Functional fatigue protocols
199 citations
TL;DR: It is concluded that during an endurance event such as the Tour de France, although the overall contribution of moderate (VT1 to VT2) or high intensity exercise (>VT2) is substantially lower than that of light, aerobic exercise (
Abstract: The aim of the present investigation was to evaluate the heart rate response of 8 professional cyclists (26+/-3 yr; 68.9+/-5.2 kg; V02max: 74.0+/-5.8 ml x kg(-1) x min(-1)) during the 3-week Tour de France as an indicator of exercise intensity. Subjects wore a heart rate telemeter during 22 competition stages and recorded data were analysed using computer software. Two reference heart rates (corresponding to the first and second ventilatory thresholds or VT1 and VT2) were used to establish three levels of exercise intensity defined as phases I ( VT2) is substantially lower than that of light, aerobic exercise (
196 citations
TL;DR: Aerobic exercise decreased both central and peripheral arterial stiffness, while resistance exercise significantly increased central arterials stiffness only.
Abstract: We examined arterial stiffness, baroreflex sensitivity (BRS), and systolic arterial pressure (SAP) variability after an acute bout of aerobic exercise compared to resistance exercise. We hypothesized that arterial stiffness would be reduced after aerobic exercise, while it would be increased after resistance exercise, and these alterations would be associated with differential changes in BRS and SAP variability. Arterial stiffness, BRS, and SAP variability were assessed before and 20 min after a bout of aerobic exercise and resistance exercise in 13 male participants. Pulse wave velocity (PWV) was used to measure central (carotid-femoral) and peripheral (femoral-dorsalis pedis) arterial stiffness. BRS was derived via the sequence technique. Spectral decomposition of beat-to-beat SAP variability was used as an estimate of sympathetic vasomotor tone. A mode-by-time interaction (p < 0.001) was detected for central PWV, due to an increase in PWV (p < 0.05) following resistance exercise and a decrease in PWV following aerobic exercise (p < 0.05). A mode-by-time interaction was also detected for peripheral PWV (p < 0.05), due to a decrease in peripheral PWV following aerobic exercise (p < 0.05) with no change following resistance exercise. BRS was significantly lower following resistance compared with aerobic exercise (p < 0.004). SAP variability increased following resistance exercise (p < 0.05) but there was no interaction. In conclusion, aerobic exercise decreased both central and peripheral arterial stiffness, while resistance exercise significantly increased central arterial stiffness only. BRS was reduced after both bouts of exercise, but significantly greater reductions were seen following resistance exercise.
163 citations
TL;DR: Both SMT and ST improved jump performance in well trained young athletes but induced opposing adaptations of the H (max)/M (max)-ratio when measured during dynamic contractions.
Abstract: In young elite athletes the influence of a sensorimotor training (SMT = balance training) on strength, jump height and spinal reflex excitability was compared with adaptations induced by strength training (ST). Seventeen athletes were randomly assigned to either a SMT or a ST group. Before and after 6 weeks of training, maximal isometric strength (MVC) and rate of force development (RFD (max)) were determined. Changes in jump height and EMG activity were assessed during squat- (SJ), countermovement- (CMJ) and drop-jump (DJ). To evaluate neural adaptations, H-reflex recruitment was recorded at rest and during dynamic activation of the plantarflexors following stance perturbation. MVC was enhanced after ST but not influenced by SMT. RFD (max) was not affected by any training. Both SMT and ST significantly improved jump performance in SJ, CMJ, and DJ. Maximum H-reflex to maximum M-wave ratios (H (max)/M (max)-ratios) at rest remained unchanged. During stance perturbation, H (max)/M (max)-ratios were significantly reduced following SMT whereas ST augmented H (max)/M (max)-ratios (p < 0.05). In contrast to other studies, no changes in RFD were found. This may be explained by methodological and/or training specific differences. However, both SMT and ST improved jump performance in well trained young athletes but induced opposing adaptations of the H (max)/M (max)-ratio when measured during dynamic contractions. These adaptations were task-specific as indicated by the unchanged reflexes at rest. Decreased spinal excitability following SMT was interpreted as the attempt to improve movement control, whereas augmented excitability following ST accounts for the effort to enhance motoneuron output. Functionally, our results emphasise that SMT is not only beneficial for prevention and rehabilitation but also improves athletic performance.
137 citations
TL;DR: It is hypothesized that a bout of high or low volume eccentric exercise would protect against muscle damage following a subsequent high volume bout and that adaptation would be attributable to neural changes, independent of the initial exercise volume.
Abstract: We hypothesized that a bout of high or low volume eccentric exercise would protect against muscle damage following a subsequent high volume bout and that adaptation would be attributable to neural changes, independent of the initial exercise volume. Sixteen males performed either 45 (ECC45) or 10 (ECC10) maximal eccentric contractions using the elbow flexors, followed by an ECC45 bout 2 weeks later. Damage markers were measured for the following 96 h; EMG and work done during the first 10 eccentric contractions were also recorded. CK, soreness, and decrements in MVC and range of motion (ROM) were greater in bout 1 than bout 2 (p < 0.01). Soreness, MVC and ROM were greater after the initial ECC45 bout compared to the initial ECC10 bout and the repeated bouts of ECC45 exercise in both groups (p < 0.01). Median frequency decreased from bout 1 to bout 2 (p < 0.001), no differences between groups were observed. An ECC45 bout of maximal eccentric exercise causes more initial damage than an ECC10 bout of maximal eccentric exercise, although both confer protection from subsequent ECC45 bouts of maximal eccentric contractions, which are attributable, at least in part, to a shift in the frequency content of EMG.
TL;DR: The findings of the study point towards the need for improvement of specific knowledge of doping among students and that their attitude towards doping must be altered.
Abstract: Goal-directed measures to prevent doping and drug abuse in sports requires empirical data. In this connection, a cross-sectional analysis was carried out in 2004. The purpose of the study, on the one hand, was to register reliable data of the current situation in Thuringia, and, on the other hand it was to give information on possible interventional steps with scientific support. Within three months, 2319 adolescents from 16 Thuringian schools (5 regular schools, 4 secondary schools, 3 sport schools and 4 vocational schools) were surveyed. Three hundred and forty-six (15.1 %) students out of 2287 students (26 students without a statement) indicated use of prohibited substances from the WADA list in the previous year: 16 (0.7 %) anabolic-androgenic steroids (AAS), 10 (0.4 %) growth hormones, 56 (2.4 %) stimulants, 305 (13.2 %) cannabis, 2 (0.1 %) diuretics, 52 (2.2 %) cocaine/heroin and 6 (0.3 %) erythropoeitin. Moreover, nonathletes (N = 490) reported a substance use that was approximately 5.0 % higher than that of recreational athletes (N = 1254) and nearly three times higher than that of competitive athletes (497). All three groups (nonathletes, recreational athletes and competitive athletes) performed poorly on a knowledge test regarding doping in general with an average below 60 % in each case. Another main aspect of the study was to determine factors influencing substance use in sports. Besides the doping specific knowledge (beta = 0.06, p < 0.05), age contributed (beta = 0.09, p < 0.05), as well as anti-doping attitude (beta = -0.34, p < 0.05), to the resulting variance. Gender, however, played no role. The findings of the study point towards the need for improvement of specific knowledge of doping among students and that their attitude towards doping must be altered. The goal in this case is to test the effectiveness of appropriate scientific intervention.
TL;DR: The concurrent explosive strength and endurance training improved anaerobic and selective neuromuscular performance characteristics in young distance runners without decreases in aerobic capacity, although almost 20% of the total training volume was replaced by explosive strength training for eight weeks.
Abstract: To study effects of concurrent explosive strength and endurance training on aerobic and anaerobic performance and neuromuscular characteristics, 13 experimental (E) and 12 control (C) young (16 - 18 years) distance runners trained for eight weeks with the same total training volume but 19% of the endurance training in E was replaced by explosive training. Maximal speed of maximal anaerobic running test and 30-m speed improved in E by 3.0 +/- 2.0% (p < 0.01) and by 1.1 +/- 1.3% (p < 0.05), respectively. Maximal speed of aerobic running test, maximal oxygen uptake and running economy remained unchanged in both groups. Concentric and isometric leg extension forces increased in E but not in C. E also improved (p < 0.05) force-time characteristics accompanied by increased (p < 0.05) rapid neural activation of the muscles. The thickness of quadriceps femoris increased in E by 3.9 +/- 4.7% (p < 0.01) and in C by 1.9 +/- 2.0% (p < 0.05). The concurrent explosive strength and endurance training improved anaerobic and selective neuromuscular performance characteristics in young distance runners without decreases in aerobic capacity, although almost 20% of the total training volume was replaced by explosive strength training for eight weeks. The neuromuscular improvements could be explained primarily by neural adaptations.
TL;DR: Music affects warm-up and may have a transient beneficial effect on anaerobic performance in elite national level adolescent volleyball players and had no significant effect on meanAnaerobic output or fatigue index in both genders.
Abstract: Music is believed to improve athletic performance. The aim of the present study was to determine the effect of arousing music during warm-up on anaerobic performance in elite national level adolescent volleyball players. Twenty-four players (12 males and 12 females) performed the Wingate Anaerobic Test following a 10-minute warm-up with and without music (two separate occasions, random order). During warm-up with music, mean heart rate was significantly higher. Following the warm-up with music, peak anaerobic power was significantly higher in all volleyball players (10.7 +/- 0.3 vs. 11.1 +/- 0.3 Watts/kg, p < 0.05, without and with music, respectively). Gender did not influence the effect of music on peak anaerobic power. Music had no significant effect on mean anaerobic output or fatigue index in both genders. Music affects warm-up and may have a transient beneficial effect on anaerobic performance.
TL;DR: This study has shown that VTs could be assessed during an incremental running test performed on a track using a simple beat-to-beat heart rate monitor, which is less expensive and complex than the classical respiratory measurement devices.
Abstract: The present study examined whether the ventilatory thresholds during an incremental exhaustive running test could be determined using heart rate variability (HRV) analysis. Beat-to-beat RR interval, V(.-)O (2), V(.-)CO (2) and V(.-) (E) of twelve professional soccer players were collected during an incremental test performed on a track until exhaustion. The "smoothed pseudo Wigner-Ville distribution" (SPWVD) time-frequency analysis method was applied to the RR time series to compute the usual HRV components vs. running speed stages. The ventilatory equivalent method was used to assess the ventilatory thresholds (VT1 and VT2) from respiratory components. In addition, ventilatory thresholds were assessed from the instantaneous components of respiratory sinus arrhythmia (RSA) by two different methods: 1) from the high frequency peak of HRV ( FHF), and 2) from the product of the spectral power contained within the high frequency band (0.15 Hz to fmax) by FHF (HF x FHF) giving two thresholds: HFT1 and HFT2. Since the relationship between FHF and running speed was linear for all subjects, the VTs could not be determined from FHF. No significant differences were found between respective running speeds at VT1 vs. HFT1 (9.83 +/- 1.12 vs. 10.08 +/- 1.29 km x h (-1), n.s.) nor between the respective running speeds at VT2 vs. HFT2 (12.55 +/- 1.31 vs. 12.58 +/- 1.33 km x h (-1), n.s.). Linear regression analysis showed a strong correlation between VT1 vs. HFT1 (R (2) = 0.94, p < 0.001) and VT2 vs. HFT2 (R (2) = 0.96, p < 0.001). The Bland-Altman plot analysis reveals that the assessment from RSA gives an accurate estimation of the VTs, with HF x FHF providing a reliable index for the ventilatory thresholds detection. This study has shown that VTs could be assessed during an incremental running test performed on a track using a simple beat-to-beat heart rate monitor, which is less expensive and complex than the classical respiratory measurement devices.
TL;DR: The data suggest that protein carbonyl concentration is elevated by cycling exercise performed at 70 % VO (2peak), is greater following longer duration rides, begins to recover within one hour following exercise, and is not different between men and women.
Abstract: The purpose of this study was to determine the effect of aerobic exercise duration on plasma protein carbonyl concentrations, a marker of protein oxidation, in aerobically trained men and women. Eight men (age: 27 +/- 4 years, VO (2peak): 4.09 +/- 0.26 L x min (-1); mean +/- SD) and 7 women (age: 27 +/- 6 years, VO (2peak): 2.33 +/- 0.24 L x min (-1)) exercised on an electrically-braked cycle ergometer at 70 % VO (2peak) for 30, 60 or 120 minutes on three separate days. Plasma samples collected before and immediately, 30- and 60-minutes post-exercise were analyzed for protein carbonyls. Mean oxygen uptake was greater for men in all conditions (2.75 +/- 0.03 L x min (-1); 38 +/- 0.43 ml x kg (-1) x min (-1)) compared to women (1.57 +/- 0.03 L x min (-1); 24.1 +/- 0.47 ml x kg (-1) x min (-1)). Total work performed during the exercise sessions was also greater for men than for women during the 30 (368 +/- 11 versus 223 +/- 7 kJ), 60 (697 +/- 17 versus 423 +/- 18 kJ), and 120-minute conditions (1173 +/- 44 versus 726 +/- 28 kJ) (Mean +/- SEM). Although these comparisons were significant (p < 0.0001), sex differences in total work performed and mean VO (2) did not result in sex differences in protein carbonyls. However, a condition by time interaction was observed with greater post-exercise values following the 120-minute condition compared to both the 30- and 60-minute conditions. Protein carbonyl concentration was greatest immediately post-exercise for both men and women and generally declined in a linear trend through one hour of recovery. These data suggest that protein carbonyl concentration is elevated by cycling exercise performed at 70 % VO (2peak), is greater following longer duration rides, begins to recover within one hour following exercise, and is not different between men and women.
TL;DR: The main finding is that in the authors' sample of trained subjects significant age-related losses in endurance performance did not occur before the age of 50 years, suggesting that the majority of older athletes are able to maintain a high degree of physical plasticity.
Abstract: We examined age-related changes in endurance performance of marathon and half-marathon finishers. A total of 405 515 running times were separated into groups based on age, sex, and distance. After exclusion of repetitive running times, 300 757 runners were analyzed by ANOVA (factors: age, sex). For each age group (six decades, 20-79 years), mean running times for all finishers, as well as top-ten performers, were assessed. As expected, age and sex had significant influence on running times. Female running times were about 10 % (marathon) and 13 % (half-marathon) above the corresponding times of their age-matched peers. The main finding is that in our sample of trained subjects significant age-related losses in endurance performance did not occur before the age of 50 years. Mean marathon and half-marathon times were virtually identical for the age groups from 20-49 years. Moreover, age-related performance decreases (p < 0.01) of the 50 - 69-year-old subjects were only in the range of 2.6 - 4.4 % per decade. These results suggest that the majority of older athletes are able to maintain a high degree of physical plasticity. The hypothesis that lifestyle factors have considerably stronger influences on functional capacity than the factor age is also supported by these findings from physically active and fit elderly.
TL;DR: Over-the-muscle electrostimulation would neither result in motor unit recruitment according to Henneman's size principle nor would it result in a reversal in voluntary recruitment order.
Abstract: Whether the involvement of motor units is different between surface neuromuscular electrostimulation and voluntary activation remains an unresolved issue. The aim of this pilot study was to verify if motor unit activation during electrostimulation is nonselective/random (i.e., without obvious sequencing related to fibre type), as recently suggested by Gregory and Bickel [6]. Sixteen healthy men randomly performed submaximal isometric contractions (10-s duration) of the quadriceps femoris muscle at 20, 40 and 60 % of maximal voluntary torque under both stimulated and voluntary conditions. During the contractions, paired stimuli were delivered to the femoral nerve (twitch interpolation technique) and the characteristics of the superimposed doublet were compared between the two conditions. For each torque level, time-to-peak torque was significantly longer (p range = 0.05 - 0.0002) during electrostimulation compared to voluntary contractions. Moreover, time-to-peak torque during voluntary trials decreased significantly when increasing the torque level from 20 to 60 % of maximal voluntary torque (p range = 0.03 - 0.0001), whereas it was unchanged during electrostimulation. In conclusion, over-the-muscle electrostimulation would neither result in motor unit recruitment according to Henneman's size principle nor would it result in a reversal in voluntary recruitment order. During electrostimulation, muscle fibres are activated without obvious sequencing related to fibre type.
TL;DR: Cold water immersion caused a significant decrease in sprint cycling performance with one-hour recovery between tests, and peak power, total work and postexercise blood lactate were significantly reduced following cold water immersion compared to the first exercise test and the control condition.
Abstract: This study investigated the effects of cold water immersion on recovery from anaerobic cycling. Seventeen (13 male, 4 female) active subjects underwent a crossover, randomised design involving two testing sessions 2 - 6 d apart. Testing involved two 30-s maximal cycling efforts separated by a one-hour recovery period of 10-min cycling warm-down followed by either passive rest or 15-min cold water immersion (13 - 14 degrees C) with passive rest. Peak power, total work and postexercise blood lactate were significantly reduced following cold water immersion compared to the first exercise test and the control condition. These variables did not differ significantly between the control tests. Peak exercise heart rate was significantly lower after cold water immersion compared to the control. Time to peak power, rating of perceived exertion, and blood pH were not affected by cold water immersion compared to the control. Core temperature rose significantly (0.3 degrees C) during ice bath immersion but a similar increase also occurred in the control condition. Therefore, cold water immersion caused a significant decrease in sprint cycling performance with one-hour recovery between tests.
TL;DR: Good golf performance in this competition was related to low T/C ratio and CSAI-2 somatic anxiety with physiological measures of anxiety, indicating a significant hormonal response during 10 hours of competitive golf.
Abstract: The purpose of this investigation was to study the effects of 36 continuous holes of competitive golf on salivary testosterone, cortisol, and testosterone-to-cortisol ratio and their relation to performance in eight elite male collegiate golfers (age 20.3 [± 1.5] years). Thirty-six holes of a 54-hole NCAA golf tournament were played on the first day of the competition. A saliva sample was taken 45 minutes prior to the round and immediately following each hole for a total of 37 samples per subject. Time matched baseline samples were collected on a different day to account for circadian variation. Six-hole areas under the curve (AUC) values were calculated for endocrine measures. Significant (p < 0.05) increases were noted for cortisol during competition, however, testosterone did not change during competition compared to baseline. Testosterone-to-cortisol (T/C) ratio was significantly lower throughout the competition compared to baseline measures. Thirty-six-hole AUC testosterone-to-cortisol ratio response was correlated (r = 0.82) to 36-hole score. There was a high correlation between pre-round testosterone (r = 0.71), T/C ratio response (r = 0.82), and 36-hole score. CSAI-2 somatic anxiety was correlated to pre-round cortisol (r = 0.81) and testosterone (r = - 0.80) response. These results indicate a significant hormonal response during 10 hours of competitive golf. Good golf performance (low golf scores) in this competition was related to low T/C ratio (r = .82). Additionally, results from this investigation validated CSAI-2 somatic anxiety with physiological measures of anxiety.
TL;DR: The data indicate that while the prevalence of clinical eating disorders is low in judo athletes, many are "at risk" for an eating disorder, which places them at an increased risk for menstrual irregularity and bone injuries.
Abstract: The aim of the study was to examine the prevalence and relationships between disordered eating, menstrual irregularity, musculoskeletal injuries and psychological characteristics in 24 judo athletes (12 females and 12 males) and 31 controls (14 females and 17 males). All these parameters were assessed by a health/medical, dieting and menstrual history questionnaire, the Eating Attitudes Test (EAT-26), the Multidimensional perfectionism scale, the Rosenberg Self-esteem, the Body esteem scale, and the Profile of Mood States. Body mass index (BMI) was also computed. Twenty-five percent of female athletes would be "at risk" of EDs (EAT-26 > 20) and 0 % in the other sample groups. Bone injuries sustained over the judo athlete career were reported by 25 % of females and 33.3 % of males, while 35.7 % of the female controls reported bone injuries. The total frequency of menstrual dysfunction among judo athletes was 58.3 %, while 7.1 % of female controls reported oligoamenorrhea. Regression analyses showed that BE-Weight Satisfaction and BMI contributed to 54.6 % and 17 % of the variance, respectively, in the prediction of log-transformed Global EAT scores among female judo athletes. These data indicate that while the prevalence of clinical eating disorders is low in judo athletes, many are "at risk" for an eating disorder, which places them at an increased risk for menstrual irregularity and bone injuries. This study also highlights the relevance of body esteem to eating disorder symptoms.
TL;DR: Elevated initial HF levels could be important in the parasympathetic activity increases during taper and, hence, in swimming performance improvement.
Abstract: The aim of the present study was to investigate the relationships between heart rate variability (HRV) changes and both training variations and performances in elite swimmers. A secondary purpose was to measure catecholamine urinary excretion in elite swimmers to validate the HRV indices of sympathetic activity during training. Thirteen swimmers (4 females and 9 males) were tested before and after 4 weeks of intense training (IT) and 3 weeks of reduced training (RT). At the end of each period, the swimmers participated in an official competition of their best event. Individual performances were expressed as percentage of the previous season's best performance. Spectral analysis was used to investigate RR interval variability. HRV indices failed to show any significant changes between the study periods (p>0.05). Pre-IT HF was correlated with performance (r=0.45; p=0.05) and HFnu (r=0.59; p<0.05) during RT. On the other hand, once RT was completed, HFnu was correlated positively to performance (r=0.81; p<0.01) and negatively to fatigue (r=- 0.63; p<0.03). Conversely, the indices of sympathetic activity, i.e., LFnu and LF/HF ratio were inversely related to performance (both r=- 0.81; p<0.01); total fatigue score was correlated to the changes in HFnu (r=- 0.63; p<0.03) and in the LF/HF ratio (r=0.58; p<0.05). Changes in the adrenaline/noradrenaline ratio over the follow-up period were related to the changes in the LF/HF ratio (r=0.45; p<0.03). In highly trained swimmers coping well with a training program, including 4 weeks of IT followed by 3 weeks of RT, HRV indices were unaltered. On the other hand, after the 3 weeks of RT, HFnu was positively related to performance and inversely related to the fatigue score. Thus, elevated initial HF levels could be important in the parasympathetic activity increases during taper and, hence, in swimming performance improvement.
TL;DR: The aim of this study was to evaluate the demands of riding a "Grand Tour" by monitoring both heart rate and power output in 15 professional cyclists by establishing average power, heart rate (HR) and cadence produced in different terrain categories.
Abstract: The aim of this study was to evaluate the demands of riding a "Grand Tour" by monitoring both heart rate and power output in 15 professional cyclists. SRM power output profiles (SRM Trainingsystem, Julich, Germany) were collected during 148 mass start stages during the 2005 Tour de France and analyzed to establish average power, heart rate (HR) and cadence produced in different terrain categories (flat [FLT]; semi-mountainous [SMT]; mountainous [MT]). The maximal mean power (MMP) for progressively longer durations was quantified. Average HR was similar between FLT (133 +/- 10 bpm) and SMT (134 +/- 8 bpm) but higher during MT (140 +/- 3 bpm). Average power output revealed a similar trend (FLT 218 +/- 21 W [3.1 +/- 0.3 W/kg], SMT 228 +/- 22 W [3.3 +/- 0.3 W/kg], and MT 234 +/- 13 W [3.3 +/- 0.2 W/kg]). Cadence during MT was approximately 6 - 7 rpm lower (81 +/- 15 rpm) compared to FLT or SMT. During MT stages, the MMP for 1800 sec. was highest (394 W vs. 342 W) but the MMP 15 was lower (836 W vs. 895 W) compared to FLT. The data document comprehensively the power output demands during the Tour de France.
TL;DR: Results provide partial support for the benefit of acute aerobic exercise on cognitive flexibility in late middle-aged individuals.
Abstract: Research has shown that aerobic exercise enhances cognitive function, specifically executive functions. This study examines the effect of acute aerobic exercise on cognitive flexibility - an executive function - in late middle-aged individuals. Fourteen men and 45 women aged 50 - 64, were randomly assigned to moderate exercise (60 % of heart rate reserve), moderately-intense (70 % of heart rate reserve) exercise, and movie-watching control groups after a maximal exercise test. Prior to and following the exercise or control sessions participants performed two cognitive tasks: the Alternate Uses assessing cognitive flexibility and the Digit Span Forward subtest from the Wechsler Adult Intelligence Scale - Revised assessing attention span. Results indicated significant improvement in Alternate Uses in the exercise groups but not in the control group. No group differences were indicated on the Digit Span. These results provide partial support for the benefit of acute aerobic exercise on cognitive flexibility.
TL;DR: Cognitive performance following exercise is hypothesized to be related to metabolic arousal following strenuous physical activity, and the effects of exercise-induced dehydration and fluid ingestion on men's cognitive performance were assessed.
Abstract: The effects of exercise-induced dehydration and fluid ingestion on men's cognitive performance were assessed. Eleven young men attended sepa- rate sessions in which each individual cycled in a controlled environment at 60 % of V u O2max for pe- riods of 15, 60, or 120 min without fluid replace- ment or 120 min with fluid replacement. Imme- diately following the assigned submaximal exer- cise period, the participant completed a graded exercise test to voluntary exhaustion. An execu- tive processing test and a short-term memory test were performed prior to and immediately following exercise. Choice-response times during the executive processing test decreased following exercise, regardless of the level of dehydration. Choice-response errors increased following exer- cise, but only on trials requiring set shifting. Short-term memory performance improved fol- lowing exercise, regardless of the level of dehy- dration. Changes in cognitive performance fol- lowing exercise are hypothesized to be related to metabolic arousal following strenuous physical " information processing l " executive function l " memory l " fatigue
TL;DR: It was showed that the muscle strengths of the operated limb had a positive association with the functional outcome of the knee in the long-term and support the use of active rehabilitation after ACL reconstruction.
Abstract: The quadriceps and hamstring muscle strengths of 16 patients operated using a bone-patellar tendon-bone (BTB) autograft and 32 patients operated using a quadruple hamstring autograft for an arthroscopic anterior cruciate ligament (ACL) reconstruction were analyzed 4- to 7-years postoperatively. Standardized isokinetic testing, a clinical evaluation and instrumented assessment of knee laxity were done. The findings showed no significant strength deficits between the patients in the BTB and Hamstring groups and the deficits were, in general, small. The quadriceps and hamstring muscle strengths were better in patients with a longer than shorter follow-up and stable knees had less knee flexion torque deficit than unstable knees. Strength deficit was associated with lower Lysholm knee scores. The findings of this study showed that the muscle strengths of the operated limb had a positive association with the functional outcome of the knee in the long-term and support the use of active rehabilitation after ACL reconstruction.
TL;DR: Research is now required to determine the optimal training regime to enhance balance ability and whether this translates to a reduction in the incidence of ankle injuries.
Abstract: This project measured pre-season balance ability and determined its relationship to knee and ankle ligament injuries during the season for professional Australian footballers. The balance test involved the players stepping onto a foam balance mat on top of a force plate and maintaining single limb balance. Throughout the playing season, injuries were monitored. The results from two hundred and ten players participating in this project were analysed. During the 2003 season, 8 % (17 out of 210) sustained a knee ligament injury and 10 % (21 out of 210) sustained an ankle ligament injury. Multivariate analysis revealed that pre-season balance ability was a significant independent predictor of ankle ligament injury. Players with low balance ability had at least twice as many ankle ligaments injuries as those with average or good balance ability. Balance ability was not a significant predictor of knee ligament injuries. The height of the players was the only significant independent predictor of knee ligament injuries. Low pre-season balance ability was associated with an increased risk of ankle ligament injury. A modifiable injury risk factor has been identified. Research is now required to determine the optimal training regime to enhance balance ability and whether this translates to a reduction in the incidence of ankle injuries.
TL;DR: It is concluded that independent of the type of ergometry the force-velocity relationship is similar in the measured range of velocities which suggests that the number of muscle groups and joints engaged in movement are more important than body balance and weight-bearing factors present while running on a treadmill.
Abstract: Since body balance and weight-bearing factors present while running on the treadmill might cause additional muscle recruitment and thus could influence the force-velocity relationship and power, the present study was undertaken to find out whether the F-V and F-P relationships measured while running on the treadmill are different from the respective indices measured during cycling. On two separate occasions, 32 male subjects were tested using a series of 5 sec, all-out sprints against different braking forces on the Gymrol Sprint treadmill and on the Monark ergometer. The maximal peak power (PPmax) and maximal mean power (MPmax) were measured. The equation: EP = 0.5 maximal force (Fo) x0.5 maximal velocity (Vo) was used to calculate the estimated values of peak power (EPP) and mean power (EMP). The F-V relationship was linear in both cycle ergometer and treadmill measurements. PPmax, MPmax, EPP, and EMP values on the treadmill were lower than the respective values on the ergometer. EPP on the ergometer and on the treadmill, as well as EMP values on the ergometer, were slightly higher than the corresponding measured values of PPmax and MPmax. The levels of braking force at which PP, MP, PPmax, and MPmax were obtained were lower on the ergometer than on the treadmill. High correlation coefficients were found between PPmax, MPmax, EPP, and EMP measured on the ergometer and on the treadmill (r = 0.86, r = 0.84, r = 0.71, r = 0.78, respectively, P<0.01). In both tests, significant relationships between PPmax, MPmax, EPP, and EMP were observed. It is concluded that independent of the type of ergometry the force-velocity relationship is similar in the measured range of velocities which suggests that the number of muscle groups and joints engaged in movement are more important than body balance and weight-bearing factors present while running on a treadmill.
TL;DR: It is concluded that acute and chronic exercise does not directly affect circulating adiponectin or oligomer distribution in lean and healthy individuals, and specifically HMW adip onectin is closely correlated with HDL cholesterol.
Abstract: Beneficial effects of physical exercise include improved insulin sensitivity, which may be affected by a modulated release of adiponectin, which is exclusively synthesized in white adipose tissue and mediates insulin sensitivity. Adiponectin circulates in three different oligomers, which also have a distinct biological function. We therefore aimed to investigate the distribution of adiponectin oligomers in human serum in relation to physical activity. Thirty-eight lean and healthy individuals were investigated. Seven healthy women and 8 healthy men volunteered to investigate the effect of chronic exercise, at 3 different time points with different training intensities. These individuals were all highly trained and were compared to a control group with low physical activity (n = 15). For studying acute exercise effects, 8 healthy men participated in a bicycle test. Adiponectin was determined by ELISA, oligomers were detected by non-denaturating western blot. Total adiponectin and oligomers were unchanged by acute exercise. LDL cholesterol was significantly lower in the chronic exercise group (p = 0.03). Total adiponectin levels and oligomers were not different between these two groups and were unaltered by different training intensities. However, total adiponectin and specifically HMW oligomers correlated with HDL cholesterol (r = 0.459; p = 0.009). We conclude that acute and chronic exercise does not directly affect circulating adiponectin or oligomer distribution in lean and healthy individuals. Whether such regulation is relevant in individuals with a metabolic disorder remains to be determined. However, our data suggest that adiponectin oligomers have distinct physiological functions IN VIVO, and specifically HMW adiponectin is closely correlated with HDL cholesterol.
TL;DR: The results of this study revealed a decline in the endurance ratio compared with the maximal strength ratio in the dominant leg after 30 repetitions and a difference in resistance to fatigue provokes an imbalance that may affect the stabilizing function of the thigh muscles.
Abstract: An imbalance in the agonist/antagonist ratio has been identified as a pathologic factor Using an isokinetic dynamometer, several studies have investigated the loss of quadriceps strength due to fatigue, but few have explored this phenomenon in the hamstrings This study assessed the decline in strength of the hamstring and quadriceps muscles with fatigue The goal was to determine whether a divergence in the decline in strength occurs that would affect the hamstring to quadriceps ratio of endurance Twenty-seven professional soccer players were selected for endurance testing to evaluate fatigue on an isokinetic dynamometer The decline in hamstring strength was significantly greater than that of the quadriceps after 15 repetitions for the dominant leg and after 40 repetitions for the nondominant leg This study also revealed a decline in the endurance ratio compared with the maximal strength ratio in the dominant leg after 30 repetitions In fatigue states, the decline in hamstring strength diverges from that of the quadriceps in both legs This difference in resistance to fatigue provokes an imbalance that may affect the stabilizing function of the thigh muscles These results can be considered as indicators of an increased risk of injury during exhausting effort