Neuromuscular,anaerobic, and aerobic performance characteristics of elite power athletes

Summary Various aspects of neuromuscular, anaerobic, and aerobic performance capacity were investigated in four powerlifters, seven bodybuilders, and three wrestlers with a history of specific training for several years. The data (means ± SD) showed that the three subject groups possessed similar values for maximal isometric force per unit bodyweight (50.7±9.6, 49.3±4.1, and 49.3±10.9 N/kg, respectively).However, significant (P<0.05) differences were observed in the times for isometric force production, so that e.g., times to produce a 30% force level were shorter for the wrestlers and bodybuilders (28.3±3.1 and 26.4±6.6 ms) than that (53.3±23.7 ms) for the powerlifters. Utilization of elastic energy by the wrestlers was significantly (P<0.05) better than that of the other two subject groups, as judged from differences between the counter-movement and squat jumps at 0, 40, and 100 kg's loads. No differences were observed between the groups in anaerobic power in a 1-min maximal test, but the values for max were higher (P<0.05) among the wrestlers and bodybuilders (57.8±6.6 and 50.8±6.8 ml·kg^–1·min^–1) as compared to the powerlifters (41.9±7.2 ml ·kg^–1·min^–1). Within the limitations of the subject sample, no differences of a statistical significancy were observed between the groups in fibre distribution, fibre areas, or the area ratio of fast (FT) and slow (ST) twitch fibres in vastus lateralis. In all subjects the vertical jumping height was positively (P<0.01) correlated with the FT fibre distribution, and negatively with the time of isometric force production (P<0.05). Maximal force was correlated (P<0.001) with thigh girth. Muscle cross-sectional area did not correlate with mean fibre area. It was assumed that the selected aspects of neuromuscular, anaerobic, and aerobic performance capacity may be influenced by muscle structure, but also specifically and/or simultaneously by training lasting for several years.     

Three-dimensional surfaces for human muscle kinetics

Summary Torque, angular velocity and angular position data were collected on six subjects performing maximum knee extensions at 11 speeds. Three-dimensional (3-D) surfaces were drawn for each subject and for the normalised, averaged data. For each subject, the moment arms of knee extensor and patella excursion were determined from radiographs and averaged across subjects. These data were then used to convert the angular data to linear force, velocity and information on muscle length. Surfaces were plotted for these data and evaluated. Results indicate a major difference between the knee positions for production of peak force or torque. Peak linear force was found to occur at an average of 75° of flexion, while peak torque was found at 57°. It was also suggested that 3-D surfaces provide more information than the traditional methods of presenting dynamic strength results.Currently on leave of absence from the University of Otago     

Skeletal muscle properties and performance in elite female track athletes

Summary Selected biochemical and physiological properties of skeletal muscle were studied in light of performance capabilities in 24 elite female track athletes. The feasibility of quantifying end point histochemistry and relating oxidative staining density (reduced nicotinomide adenine dinucleotide diaphorase: NADH-D) to whole body maximal oxygen consumption ( max) was also investigated, while muscle fiber types, classified according to alkaline APTase stains, were studied and related to muscle oxidative capacity (succinate dehydrogenase: SDH), max and “in vivo” torque-velocity properties. Muscle biopsies were taken from the vastus lateralis of each subject and maximal knee extensor torques were recorded at 30‡ from full extension at four selected velocities. While results confirm earlier reports on skeletal muscle properties and performance it was concluded that end point histochemistry could be reliably quantified and that an “oxidative” stain such as NADH-D correlates extremely well with max (r=0.86,p<0.001) whereas correlations between %slow twitch fibres (alkaline ATPase stain) and max were lower (r=0.44,p<0.05). Additionally, as knee extension velocity increased from 0–1.7 rad·s⁻¹ angle specific extensor torque production did not decline as observed in vitro and pentathletes displayed significantly larger torques at all velocities when compared to the other athletes. These data confirm that while myofibrillar ATPase staining correlates with force-velocity properties of muscle, max is better correlated with quantified oxidative staining. Supported in part by a Public Health Service Biomedical Research Support Grant to UCLA, Public Health Service Grant 10423 and by the National Aeronautics and Space Administration (NASA)     

Eccentric and concentric torque-velocity relationships during arm flexion and extension

Summary Forty men were tested with a computerized dynamometer for concentric and eccentric torques during arm flexion and extension at 0.52, 1.57, and 2.09 rad·s^–1. Based on the summed concentric and eccentric torque scores, subjects were placed into a high strength (HS) or low strength (LS) group. The eccentric and concentric segments of the torque-velocity curves (TVCs) were generated using peak torque and constant-angle torque (CAT) at 1.57 and 2.36 rad. Angle of peak torque was also recorded. Compared to LS, HS had significantly greater estimated lean body mass (+ 10.2 kg) and approximately 25% greater average torque output. Reliability of the peak torque scores on 2 days in 20 subjects wasr0.85. The difference between observed torques and the mathematically computed criterion torque scores averaged 1% for three validation loads that ranged from 11.4 to 90.4 kg. Statistical analysis revealed that torque output in LS plateaued at low concentric velocities and was also flattened with increasing eccentric velocities. Conversely, torque ouptput for HS increased with decreasing concentric velocities and increased with increasing eccentric velocities. The method of plotting the TVCs for peak or CAT did not influence the pattern of TVC. Eccentric flexion peak torque occurred at a significantly shorter muscle length (1.88 rad) than concentric torque (2.12 rad). This difference was also present for extension; it was 1.88 rad for eccentric and 2.03 rad for concentric torque. These findings are discussed in terms of study design, neural inhibition, activation history, muscle-tendon elasticity, muscle fiber types, muscle architecture, and methodological considerations. The present results illustrate the importance of strength level to explain individual differences in TVC.     

Serum hormone concentrations during prolonged training in elite endurance-trained and strength-trained athletes

Summary A study of 1 year was performed on nine elite endurance-trained athletes (swimmers) and on eight elite strength-trained athletes (weightlifters) in order to examine the effects of training on the endocrine responses and on physical performance capacity. The measurements for the determination of serum hormone concentrations were performed at about 4-month intervals during the course of the year. The primary findings demonstrated that during the first and most intensive training period of the year in preparing for the primary competitions similar but statistically insignificant changes were observed in the concentrations of serum testosterone, free testosterone and cortisol in both the endurance-trained and strength-trained groups. After that period the changes in hormonal response over the year were infrequent and minor. A significant (p<0.01) decrease occurred in the strength-trained group in serum-free testosterone during the second period, which was characterized by the highest overall amount of training. Over the entire year the concentrations of serum hormones remained statistically unaltered in both groups. Slight but statistically insignificant increases of 1.2%±0.8% and 2.1%±5.1% were observed in the competitive performances over the year in the endurance-trained and strength-trained groups, respectively. The present findings in the two groups of elite athletes, who differed greatly with regard to the type of physiological loading, demonstrated that the overall hormonal responses both during the most intensive and during prolonged training periods were rather similar and the infrequent small changes remained well within the normal physiological range. The observations further indicate that the training may not have been too strenuous, with no noticeable symptoms of overtraining, and/or that it could have been in greater amount and/or of greater intensity, leading perhaps to greater improvement in competitive performance capacity.     

Isokinematic muscle mechanics in four groups of women of increasing age

Summary The purpose of this study was to evaluate the effects of age on dynamic muscle attributes of the knee extensors and flexors in postmenopausal women. Young healthy women (3rd decade,n = 15; 4th decade,n = 5) and older healthy women (6th decade,n = 9; 7th decade,n = 6) were tested at six angular velocities from 60° · s^–1 to 400° · s^–1. The 3rd and 4th decade groups produced greater extensor and flexor values for strength related variables at all angular velocities (peak torque, angle specific torque, work, power) than both the 6th and 7th decade groups (P<0.05). However, relative changes in these variables, with increments in angular velocity, were equivalent among the groups. Analysis of the flexor: extensor ratios for these variables demonstrated a differential loss in flexor function with increased age, perhaps indicative of type II motor unit loss or muscle fibre atrophy. It is suggested that such changes may be present even within 4th decade subjects.     

The force-velocity relationship of arm flexion in untrained males and females and arm-trained athletes

Summary The force-velocity curve (FVC) of arm flexion was established in 123 untrained males and 110 untrained females aged from 15 to 36 years, and 48 arm-trained athletes competing in different sport disciplines. The FVC was described by Hill's equation and defined by the parameters: maximal static moment (M₀), maximal angular velocity (₀), maximal power (P₀) and the concavity of the FVC (H). Within the given age range the level of the curve parameters of both untrained men and women was independent of age.On average, H was the same in all three groups. As compared to M₀ of the untrained males, M₀ of the athletes was 33% higher and M₀ of the females was 38% lower; with regard to P₀ these differences were +30% and –43% respectively. ₀ was the same for trained and untrained males, wherease ₀ of the women was 10% lower than ₀ of the men.     

Effects of long-term training specificity on maximal strength and power of the upper and lower extremities in athletes from different sports

Maximal concentric one repetition maximum half-squat (1RM_HS), bench-press (1RM_BP), power-load curves during concentric actions with loads ranging from 30% to 100% of 1RM_HS and 1RM_BP were examined in 70 male subjects divided into five groups: weightlifters (WL, n=11), handball players (HP, n=19), amateur road cyclists (RC, n=18), middle-distance runners (MDR, n=10) and age-matched control subjects (C, n=12). The 1RM_HS values in WL, HP and RC were 50%, 29% and 28% greater, respectively, (P<0.001–0.01) than those recorded for MDR and C. The half-squat average power outputs at all loads examined (from 30% to 100%) in WL and HP (P<0.001 at 45% and 60% with HP) were higher (P<0.05–0.001) than those in MDR, RC and C. Average power output at the load of 30% of 1RM_HS in RC was higher (P<0.05) than that recorded in MDR and C. Maximal power output was produced at the load of 60% for HP, MDR and C, and at the load of 45% for WL and RC. The 1RM_BP in WL was larger (P<0.05) than those recorded in HP, RC, MDR and C. In the bench press, average muscle power outputs in WL and HP were higher (P<0.05–0.001) than those in MDR, RC and C, and were maximized at a load of 30% of 1RM for WL and HP, and at 45% for RC, MDR and C. In addition, the velocities that elicited the maximal power in the lower extremities were lower (≈0.75 m·s^–1) than those occurring in the upper extremities (≈1 m·s^–1). The data suggest that the magnitude of the sport-related differences in strength and/or muscle power output may be explained in part by differences in muscle cross-sectional area, fibre type distribution and in the muscle mechanics of the upper and lower limbs as well as by training background. Electronic Publication     

Neuromuscular and hormonal responses in elite athletes to two successive strength training sessions in one day

Summary Acute neuromuscular and endocrine adaptations to weight-lifting were investigated during two successive high intensity training sessions in the same day. Both the morning (I) (from 9.00 to 11.00 hours) and the afternoon (II) (from 15.00 hours to 17.00 hours) training sessions resulted in decreases in maximal isometric strength (p<0.01 and <0.05), shifts (worsening) in the force-time curve in the absolute scale (p<0.05 and ns.) and in decreases in the maximal integrated EMG (p<0.01 and <0.05) of the selected leg extensor muscles. Increases in serum total (p<0.05) and free testosterone (p<0.01) and in cortisol (p<0.01) concentrations were found during training session II. These were followed by decreases (p<0.001 andp<0.01 and ns.) in the levels of these hormones one hour after the termination of the session. The responses during the morning training session were different with regard to the decreases in serum total testosterone (p<0.05), free testosterone (ns.) and cortisol (p<0.05). Only slight changes were observed in the levels of luteinizing hormone and sex hormone-binding globulin during the training sessions. Increases (p<0.01) took place in somatotropin during both training sessions. The present findings suggest that high intensity strengthening exercises may result in acute adaptive responses in both the neuromuscular and endocrine systems. The diurnal variations may, however, partly mask the exercise-induced acute endocrinological adaptations in the morning. Recording of muscle activation and muscle strength and analysis of certain serum hormone concentrations with sufficient frequency during the training process may be useful in optimizing and controlling the contents of individual training sessions and the full training program.     

Static and dynamic assessment of the Biodex dynamometer

Summary The validity and accuracy of the Biodex dynamometer was investigated under static and dynamic conditions. Static torque and angular position output correlated well with externally derived data (r=0.998 andr>0.999, respectively). Three subjects performed maximal voluntary knee extensions and flexions at angular velocities from 60 to 450° · s^–1. Using linear accelerometry, high speed filming and Biodex software, data were collected for lever arm angular velocity and linear accelerations, and subject generated torque. Analysis of synchronized angular position and velocity changes revealed the dynamometer controlled angular velocity of the lever arm to within 3.5% of the preset value. Small transient velocity overshoots were apparent on reaching the set velocity. High frequency torque artefacts were observed at all test velocities, but most noticeably at the faster speeds, and were associated with lever arm accelerations accompanying directional changes, application of resistive torques by the dynamometer, and limb instability. Isokinematic torques collected from ten subjects (240, 300 and 400° · s^–1) identified possible errors associated with reporting knee extension torques at 30° of flexion. As a result of tissue and padding compliance, leg extension angular velocity exceeded lever arm angular velocity over most of the range of motion, while during flexion this compliance meant that knee and lever arm angles were not always identical, particularly at the start of motion. Nevertheless, the Biodex dynamometer was found to be both a valid and an accurate research tool; however, caution must be expercised when interpreting and ascribing torques and angular velocities to the limb producing motion.     

Effects of different strength training regimes on moment and power generation during dynamic knee extensions

This study examined the effect of different training regimes on moment and power generation during maximal knee extensions at low to very high extension velocities (0–1000°·s^–1 individual range). A group of 24 soccer players performed 12 weeks of progressively adjusted strength training of the knee extensors at either high resistance (HR,n=7), low resistance (LR,n=6), loaded kicking movements (FU,n=6), while one group served as controls (n=5). Moment and power generation of the knee extensors were determined before and after the training period with a nonisokinetic measuring method recently described. Following HR training, knee extension moment increased 9%–10% at knee angular velocities 0 (isometric) and 30° · s^–1 (P<0.05), peak moment increased 20% at 240–300°·s^–1 (P<0.05), while power generation increased 5%–29% at 240–480° · s^–1 (P<0.01). In addition, in the HR group maximal recorded power increased 45% (P<0.01). After FU training a 7%–13% increase in moment and power was observed at 30–180° · s^–1 (P<0.05). Following LR training, peak moment increased 9% at 120° · s^–1 (P<0.05). Improvements in knee extension moment and power were generally related to the angular velocities employed during training. However, as evaluated using the present measuring method, moment and power increased not only at very low but also at high knee angular velocities following the high-resistance strength training.     

Seasonal fluctuations of selected physiological characteristics of elite alpine skiers

The effects of heavy resistance training and jumping exercise were examined during the 1989–1990 season in 12 international level alpine skiers. The athletes were tested before, during, immediately after training and during the period off training (June, July, October 1989, April 1990). Their mechanical behaviour was investigated using firstly squat jumps performed without (SJ) or with low extra loads (20 kg, SJ_20kg) and high extra loads (equivalent to body mass on the shoulders, SJ_bm) and secondly 15–30 s continuous jumping. These tests allowed the assessment of explosive dynamic strength production (SJ and SJ_20kg), slow dynamic strength (SJ_bm) and maximal mechanical power (continuous jumping). The training adopted resulted in specific changes in neuromuscular performance; in fact all the variables studied showed a significant improvement (P<0.01) from the beginning compared to the end of training. The range of improvement was between 55.4% (SJ_bm) and 12.5% (average power during 15-s continuous jumping). The enhancement of SJ had become significant by July. Surprisingly, even when no strength or jumping training was performed during the competition period (November-April), no deterioration in the neuromuscular performance was observed, there being no significant difference between the test values obtained in October 1989 and April 1990. It was concluded that the demanding competition programme of alpine skiers may provide a training stimulus adequate to maintain the neuromuscular improvement induced by training throughout the competition season.     

Static dynamometer for the measurement of multidirectional forces exerted by the thumb

The functioning of a static dynamometer designed to measure simultaneous forces exerted by the thumb in the vertical and horizontal axes is described. The analysis of the output signals by a desktop computer program provides information regarding the forces generated in eight directions covering a plane transverse to the thumb by 45° increments. In 12 normal female subjects, the maximum voluntary torques exerted at the trapezo-metacarpal joint of the thumb were examined and the muscle activation patterns of the interosseus, flexor pollicis brevis and adductor pollicis brevis muscles were recorded in one subject. Torques and muscle activation patterns were depicted using polar plots. Dynamometric data indicate that strength varies with direction and that higher torques are obtained in directions that bring the thumb towards the palm, i.e. flexion, adduction, combined flexion-adduction and extension-adduction. Patterns of muscle activity vary according to the direction evaluated suggesting that strength depends on the number of activated muscles as well as the relative force contribution of each muscle.     

优秀青少年男子篮球运动员腰腹屈伸肌群生物力学特征

背景：目前,等速测试系统在评定各专项运动员肌肉功能的应用越来越受到重视,但运用等速肌力测试技术研究优秀青少年男子篮球运动员腰腹肌力特征的报道较少。 目的：研究优秀青少年男子篮球运动员腰腹屈伸肌群生物力学特征,为篮球项目的腰腹力量训练、科学选材和预防腰腹损伤提供依据。 方法：采用Cybex-Norm等速肌力测试系统,对广州男子篮球队运动员18人测定腰腹屈伸肌群在慢速60(°)/s和快速180(°)/s的肌力和做功情况。 结果与结论：受试者腰腹屈伸肌群的峰力矩和相对峰力矩在同一测试速度下,伸肌群大于屈肌群(P < 0.01);腰腹屈伸肌群的峰力矩、相对峰力矩、总功均随着测试速度的增加呈减小趋势(P < 0.05),伸肌群的峰力矩和相对峰力矩减少更显著(P < 0.01);腰腹屈伸肌群的相对功率随着测试速度的增加而呈上升趋势(P < 0.01);外线球员腰腹屈伸肌群各测试指标成绩优于内线球员;在等速向心收缩时,随测试速度加快,腰腹屈伸肌群的峰力矩屈伸比呈递减趋势,躯干稳定性减弱。结果提示,优秀青少年男子篮球运动员腰腹伸肌群肌力大于屈肌群;外线球员腰腹屈伸肌群的肌力优于内线球员;等速快速运动时,腰腹屈伸肌群力量减小,腰腹关节屈伸肌力平衡性减弱,应加强青少年男子篮球运动员腰腹核心肌群快速力量训练。   中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Anaerobic and aerobic peak power output and the force-velocity relationship in endurance-trained athletes: effects of aging

The aim of this investigation was to test the hypothesis that the anaerobic peak power output (P _{an, peak}) declines more than the peak aerobic power (P _{aer, peak}) with increasing age. In addition, the force-velocity (F-) relationship was studied to determine which of these two factors is primarily responsible for the expected alterations in anaerobic power. TheP _{an, peak}, the maximalF when is equal to zero (F ₀) and the maximal whenF is equal to zero (₀) were assessed byF- test i.e. a brief intense intermittent exercise test using incremental braking forces. TheP _{aer, peak} was measured by a maximal increment exercise test. A group of 12 young athletes (YA) and 12 master athletes (MA) mean age 24.8 (SEM 1.3) and 65.1 (SEM 1.2) years, respectively, participated in this study. The YA and MA had similar body masses, heights and endurance training schedules. The results showed thatP _{an, peak} was 42.7% lower in the older subjects, corresponding to mean values of 1089 (SEM 40) compared to 624 (SEM 33) W (t = 8.9,P < 0.001) for YA compared to MA, respectively. TheF ₀ andV ₀ indices showed values that were lower by 30.3% and 15.2%, respectively. TheP _{aer, peak} was 35 % lower with mean values of 323 (SEM 12) W for YA compared to 210 (SEM 6) W for MA (t = 8.3,P < 0.001). The mean maximal oxygen uptake was 34.7% lower with 4240 (SEM 160) ml · min^–1 for YA compared to 2770 (SEM 120) ml · min^–1 for MA(t = 7.2,P < 0.001).TheP _{an, peak}:P _{aer, peak} ratio and ₀/F ₀coefficient were 12.1% lower and 18.4% higher, respectively. In summary, this study showed that in endurance-trained athletes, the age-related difference inP _{an, peak} was significantly greater than that ofP _{aer, peak}. Similarly, the age-related difference inF was significantly greater than that in .     

Anxiety and performance in elite non-professional athletes

Anxiety is one of the main motivators with regards to performance of individuals in any given task, including sporting endeavours. Our study sought to assess state anxiety levels in elite non-professional sportsmen, and to investigate if anxiety correlated with sporting performance, the IDA-Q (irritability, depression & anxiety questionnaire) was used to assess 3 mental state variables in an inter-county hurling team as well as a matched non-sporting control group, and performance was judged by completion of a standard task in 2 different settings: a non-pressurised one and a highly pressurised setting. Subjects had significantly higher anxiety scores on the IDA-Q than the controls (p = 0.019). There were no significant differences and controls in the depression and irritability scales. There was a significantly negative correlation between anxiety scores and performance on the IDA-Q; spearman r = -0.57. High anxiety levels impair sporting performance.     

EMG,muscle fibre and force production characteristics during a 1 year training period in elite weight-lifters

Summary The effects of a 1 year training period on 13 elite weight-lifters were investigated by periodical tests of electromyographic, muscle fibre and force production characteristics. A statistically non-significant increase of 3.5% in maximal isometric strength of the leg extensors, from 4841±1104 to 5010±1012 N, occured over the year. Individual changes in the high force portions of the force-velocity curve correlated (p<0.05–0.01) with changes in weight-lifting performance. Training months 5–8 were characterized by the lowest average training intensity (77.1+2.0%), and this resulted in a significant (p<0.05) decrease in maximal neural activation (IEMG) of the muscles, while the last four month period, with only a slightly higher average training intensity (79.1±3.0%), led to a significant (p<0.01) increase in maximum IEMG. Individual increases in training intensity between these two training periods correlated with individual increases both in muscular strength (p<0.05) and in the weight lifted in the clean & jerk (p<0.05). A non-significant increase of 3.9% in total mean muscle fibre area occurred over the year. The present findings demonstrate the limited potential for strength development in elite strength athletes, and suggest that the magnitudes and time courses of neural and hypertrophic adaptations in the neuromuscular system during their training may differ from those reported for previously untrained subjects. The findings additionally indicate the importance of training intensity for modifying training responses in elite strength athletes.     

Mechanical characteristics of chemically skinned guinea-pig taenia coli

Strips of intact and chemically skinned (Triton X-100) taenia coli were mounted for isometric and quick-release experiments at 23°C. Active force increased in repeated high-K⁺ induced contractures in the intact muscle. Stable maximal force was 313±24 mN/mm² (n=6). The skinned preparations activated by Ca²⁺, at 2 mM Mg²⁺, 3.2 mM MgATP and ionic strength 0.085 M, gave half maximal force atpCa=5.62±0.4 and a maximal force (63±8 mN/mm²) atpCa=4.5 (20–25 of the control K⁺-responses prior to skinning but about 60% of the first K⁺-response). Force-velocity relations were obtained from intact muscles and from the same muscles chemically skinned and activated at optimal Ca²⁺. Maximal shortening velocity (V _max) was unaltered in the skinned preparation compared to the intact muscle (0.138±0.011 vs 0.140±0.006 L/s) indicating similar kinetics of actomyosin interaction. In the intact muscle a decrease inV _max was found when the Ca²⁺ concentration was reduced. Calmodulin (1M) increased Ca²⁺ sensitivity (by about 0.6 log units) of the skinned preparation but at optimal Ca²⁺ caused no alteration in isometric force orV _max Apreliminary report of some of the results presented here was given at the Scandinavian Physiology Society Meeting in Århus, November 1981. Arner A, Hellstrand P (1982) Acta Physiol Scand (Abstract) 114: 38 A.     

Allergy and asthma in elite summer sport athletes

Exercise may increase ventilation up to 200 L/min for short periods of time in speed and power athletes, and for longer periods in endurance athletes, such as long-distance runners and swimmers. Therefore highly trained athletes are repeatedly and strongly exposed to cold air during winter training and to many pollen allergens in spring and summer. Competitive swimmers inhale and microaspirate large amounts of air that floats above the water surface, which means exposure to chlorine derivatives from swimming pool disinfectants. In the summer Olympic Games, 4% to 15% of the athletes showed evidence of asthma or used antiasthmatic medication. Asthma is most commonly found in endurance events, such as cycling, swimming, or long-distance running. The risk of asthma is especially increased among competitive swimmers, of which 36% to 79% show bronchial hyperresponsiveness to methacholine or histamine. The risk of asthma is closely associated with atopy and its severity among athletes. A few studies have investigated occurrence of exercise-induced bronchospasm among highly trained athletes. The occurrences of exercise-induced bronchospasm vary from 3% to 35% and depend on testing environment, type of exercise used, and athlete population tested. Mild eosinophilic airway inflammation has been shown to affect elite swimmers and cross-country skiers. This eosinophilic inflammation correlates with clinical parameters (ie, exercise-induced bronchial symptoms and bronchial hyperresponsiveness). Athletes commonly use antiasthmatic medication to treat their exercise-induced bronchial symptoms. However, controlled studies on their long-term effects on bronchial hyperresponsiveness and airway inflammation in the athletes are lacking. Follow-up studies on asthma in athletes are also lacking. What will happen to bronchial hyperresponsiveness and airway inflammation after discontinuation of competitional career is unclear. In the future, follow-up studies on bronchial responsiveness and airway inflammation, as well as controlled studies on both short- and long-term effects of antiasthmatic drugs in the athletes are needed.     

Muscle cross-sectional area and voluntary force production characteristics in elite strength- and endurance-trained athletes and sprinters

Summary Seven male elite strength-trained athletes (SA) from different weight categories, six elite sprinters (SPA) and seven elite endurance-trained athletes (EA) volunteered as subjects for examination of their muscle cross-sectional area (CSA), maximal voluntary isometric force, force-time and relaxation-time characteristics of the leg extensor muscles. The SA group demonstrated slightly greater CSA and maximal absolute strength than the SPA group, while the EA group demonstrated the smallest values both in CSA and especially in maximal strength (p<0.05). When the maximal forces were related to CSA of the muscles, the mean value for the SA group of 60.8±10.0 N·cm⁻² remained slightly greater than that recorded in the SPA group 55.0±3.1 N·cm⁻² and significantly greater (p<0.05) than that recorded in the EA group 49.3±4.0 N·cm⁻². The mean value in the SPA was also significantly greater (p<0.05) than that of the EA group. The isometric force-time curves differed between the groups (p<0.05−0.01) so that the times taken to produce the same absolute force were the shortest in the SPA group and the longest in the EA group. With force expressed as a percentage of the maximum, the force-time curves showed that the SPA group demonstrated still shorter times to a given value (p<0.05), especially at the lower force levels, than the other two groups. With regard to the differences in force production per CSA and in the shape of the force-time curves, the present findings may be explained by possible differences both in the rate and the amount of neural activation of the muscles and/or in the qualitative characteristics of the muscle tissue itself. The present findings characterize the very specific nature of high resistance strength-, sprint- and endurance-training stimuli over a very prolonged period of time.