Impact of (long) COVID on athletes' performance: a prospective study in elite football players.

OBJECTIVES: To investigate possible persistent performance deficits after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in elite athletes. METHODS: A prospective cohort study in three Belgian professional male football teams was performed during the 2020 - 2021 season. Participants were submitted to strength, jump, and sprint tests and an aerobic performance test (the Yo-Yo Intermittent Recovery test (YYIR)). These tests were repeated at fixed time intervals throughout the season. Assessment of SARS-CoV-2 infection was performed by a polymerase chain reaction (PCR) test before each official game. RESULTS: Of the 84 included participants, 22 were infected with SARS-CoV-2 during follow-up. At the first testing after infection (52.0 ± 11.2 days after positive PCR testing) significantly higher percentages of maximal heart rate (%HRmax) were seen - within the isolated group of infected players- during (p = .006) and after the YYIR (2 min after, p = .013), compared to pre-infection data. This increase in %HRmax was resolved at the second YYIR testing after infection (127.6 ± 33.1 days after positive PCR testing). Additionally, when comparing the first test after infection in formerly infected to non-infected athletes, significantly higher %HRmax were found during (p < .001) and after the YYIR test (p < .001),No significant deficits were found for the jump, muscular strength or sprint tests.Aerobic performance seems compromised even weeks after infection. Simultaneously, anaerobic performance seemed to be spared. Because of the potential detrimental effects on the immune system, caution might be advised with high-intensity exposure until aerobic performance is restored.KEY MESSAGESElite football players' aerobic performance seems to be affected for weeks after they return to sports after a SARS-CoV-2 infection.Similarly, anaerobic performance tests showed no discernible changes between both before and after SARS-CoV-2 infections.Regular YYIR testing is recommended to monitor aerobic performance after SARS-CoV-2 infection.

Muscle Fibre Typology as a Novel Risk Factor for Hamstring Strain Injuries in Professional Football (Soccer): A Prospective Cohort Study.

BACKGROUND: Hamstring strain injuries (HSI) are prevalent in team sports and occur frequently in the later phase of matches. In the search for interindividual factors that determine muscle fatigue and possibly injury risk, muscle fibre typology is a likely candidate. OBJECTIVE: The aim of the study was to determine whether muscle fibre typology is a risk factor for HSI. METHODS: A prospective cohort study was conducted over three seasons in professional football players competing in the Belgian Jupiler Pro League (n = 118) and in the English Premier League (n = 47). A total of 27 HSI were sustained during this period. Muscle fibre typology was non-invasively estimated using proton magnetic resonance spectroscopy and was characterized as a fast, slow, or intermediate typology based on the carnosine concentration in the soleus. A multivariate Cox model was used to identify risk factors for HSI. RESULTS: Football players exhibited a wide variety of muscle typologies (slow 44.9%, intermediate 39.8%, fast 15.3%). In the combined cohort, players with a fast typology displayed a 5.3-fold (95% confidence interval [CI] 1.92-14.8; P = 0.001) higher risk of sustaining an index HSI than slow typology players. This was also independently observed in both leagues separately as, respectively, a 6.7-fold (95% CI 1.3-34.1; P = 0.023) and a 5.1-fold (95% CI 1.2-20.4; P = 0.023) higher chance was found in fast typology players than in slow typology players of the Jupiler Pro League and the Premier League cohort. CONCLUSION: We identified muscle fibre typology as a novel and potent risk factor for HSI in team sports.

Sleep, training load and performance in elite female gymnasts.

Training load (TL) and recovery should be in optimal balance to obtain maximal performance gains. We aimed to study sleep as a recovery technique and its relationship with TL and performance in elite athletes. Twenty-six elite female artistic gymnasts were divided into an under 13 (n = 6), an under 14 (n = 6), a junior (n = 7; 14-15y) and a senior (=World Championship (WC) competitors, n = 7; ≥16y) category. Sleep, through sleep logs, and training parameters, using the session Rate of Perceived Exertion (sRPE) scale, were monitored to calculate total sleep time (TST), sleep efficiency (SE), TL, monotony and strain. Performance of WC competitors was evaluated through coach and WC qualification ranking. For the entire group, TST (effect sizes (ES) = -1.12, confidence intervals (CI) = -60:-47, P < .05) and SE (ES = -0.13, CI = -1.40:-0.10, P = .022) were shorter during week than weekend nights. TST and SE were highest in youngest gymnasts (P < .05). TL was lowest in under 13 and senior gymnasts (P < .05), while TL, monotony and strain were highest in junior gymnasts (P < .05). A negative regression was found between TST and TL the day after, while higher TL also led to lower TST the following night (P < .001). For the WC competitors, TST the night before the qualifications was shorter than the mean TST of the WC period (ES = -0.95, CI = -170:24, P = .030). TST correlated with coach ranking (r = -0.857, P = .014). Higher TL correlated with worse WC (r = 0.829, P = .042) and coach (r = 0.893, P = .007) ranking. This research in elite gymnasts indicated associations between decreased TST, augmented TL and inferior performance. Optimizing sleep and TL may therefore represent strategies to enhance performance.

Development and usability of a computer-tailored pedometer-based physical activity advice for breast cancer survivors.

This observational study aimed to adapt a computer-tailored step advice for the general population into a feasible advice for breast cancer survivors and to test its usability. First, several adaptations were made to the original design (adding cancer-related physical activity (PA) barriers and beliefs, and self-management strategies to improve survivors' personal control). Second, the adapted advice was evaluated in two phases: (1) a usability testing in healthy women (n = 3) and survivors (n = 6); and (2) a process evaluation during 3 weeks in breast cancer survivors (n = 8). Preliminary usability testing revealed no problems during logging-in; however, three survivors misinterpreted some questions. After refining the questionnaire and advice, survivors evaluated the advice as interesting, attractive to read, comprehensible and credible. Inactive survivors found the advice novel, but too long. The process evaluation indicated that the majority of the women (n = 5/8) reported increased steps. Monitoring step counts by using a pedometer was perceived as an important motivator to be more active. To conclude, this study provides initial support for the usability and acceptability of a computer-tailored pedometer-based PA advice for breast cancer survivors. After testing efficacy and effectiveness of this intervention, this tool can broaden the reach of PA promotion in breast cancer survivors.

Quadriceps muscle fatigue in trained and untrained boys.

This study aimed to explore muscle oxygen extraction and muscle activation pattern during bilateral intermittent submaximal isometric knee-extensions by combining Near-infrared Spectroscopy (NIRS) and Electromyography (EMG) measurements from the M. Vastus Lateralis. A group of highly specifically trained boys (youth sailors) (n=10) and untrained matched controls (n=10) performed 12 bouts of 90 s bilateral submaximal (30-40% MVC) isometric knee-extension interspersed with 6 s recovery-periods. Patterns of deoxygenated haemoglobin and myoglobin concentration (Deoxy[Hb+Mb]) were observed during each bout and the entire protocol. Reoxygenation Index (RI) was assessed for each recovery period as the amplitude of Deoxy[Hb+Mb]-decrease relative to amplitude of Deoxy[Hb+Mb]-increase during each bout. Root Mean Square (RMS) and Mean Power Frequency (MPF) were calculated for each bout as an average of the final 60 s. Deoxy[Hb+Mb], RI, RMS and MPF were analyzed by repeated-measures ANOVA. Results indicated significantly higher Deoxy[Hb+Mb]-increase and lower RI in specifically trained boys compared to untrained controls. These differences are presumably related to the differences in EMG-measurements which demonstrated lower RMS-increase and MPF-decrease for trained compared to untrained boys. In conclusion, specifically trained boys indicate delayed onset of muscle fatigue in comparison to untrained controls, which might be associated with the different pattern of muscle O2-extraction or muscle activation pattern (i. e., a more accurate recruitment of slow-twitch fibres).

Physical activity levels and supportive care needs for physical activity among breast cancer survivors with different psychosocial profiles: a cluster-analytical approach.

The transition from breast cancer patient to survivor is associated with many treatment-related and psychosocial factors, which can influence health behaviour and associated needs. First, this study aimed to identify clusters of treatment-related and psychosocial factors among breast cancer survivors. Second, clusters' physical activity levels and care needs for physical activity were evaluated. Breast cancer survivors (n= 440; 52 ± 8 years) (3 weeks to 6 months post treatment) completed self-reports on physical and psychological symptoms; illness representations; social support and coping; physical activity and care needs for physical activity. Analyses identified four clusters: (1) a low distress-active approach group; (2) a low distress-resigned approach group; (3) a high distress-active approach group; and (4) a high distress-emotional approach group. Physical activity levels were higher in the low distress groups than in the high distress-emotional approach group. However, women with low distress and an active approach reported equal care needs for physical activity than women with high distress and an emotional approach. These findings suggest that care needs for physical activity are unrelated to distress and actual physical activity levels. The results emphasise the importance of screening for needs and provide a framework supporting the referral of breast cancer survivors to tailored interventions.

A novel multidisciplinary educational programme for patients with chronic skin diseases: Ghent pilot project and first results.

Chronic inflammatory skin disorders have a major impact on the patients' health related quality of life. Preliminary studies to date have suggested that additional educational and psychological training programmes may be effective in the management of chronic skin diseases, although more rigid methodology is needed. Our purpose was to investigate the effect on quality of life of a novel multidisciplinary educational programme for patients, 18 years or older, with chronic skin diseases. The 12-week intervention encompasses cognitive education on skin and general health issues, and stress-reducing techniques. Quality of life questionnaires were used to assess the participants at baseline and at the end of the program. These comprehend Dermatology Life Quality Index (DLQI), Skindex-29, Psoriasis Disability Index (PDI) and Quality of Life Index for Atopic Dermatitis (QoLIAD). Fifty-five patients participated in six programmes since 2006. Forty-three patients completed the programme. Overall, compared to baseline, DLQI (n = 39) improved by 5.64 points (p < 0.001; SD ±6.09), Skindex-29 (n = 27) by 19.67 points (p < 0.001; SD ±17.37), PDI (n = 9) improved by 7.44 points (p = 0.019; SD ±7.60) and QoLIAD (n = 13) improved by 4.39 points (p = 0.036; SD ±6.69) by the end of the intervention. Preliminary results show that the quality of life of the patients with chronic skin diseases improved significantly after participation to the programme. These positive initial results are stimulating to set up a prospective controlled randomised trial investigating the impact on quality of life, the clinical efficacy and the cost-effectiveness of this educational intervention programme.

Running economy in early and late maturing youth soccer players does not differ.

PURPOSE: The aim of this study was to investigate the influence of maturity on running economy in a population of young soccer players. METHODS: 13 boys (mean age 14.3 years) active in soccer were divided into two groups: 6 early and 7 late maturers. Anthropometrical characteristics, respiratory exchange ratio, heart rate and maximal oxygen uptake were measured. Running economy was assessed at three submaximal running speeds (8, 9.5 and 11 km/h). Allometric coefficients were calculated and used to diminish the effect of body mass. In addition, running style was analysed biomechanically (stride length and meaningful kinematic values). RESULTS: There was no significant difference in the running economy of early and late maturing soccer players, nor any significant differences in mass adjusted physiological values. Therefore physiological differences cannot explain why late maturers succeed in keeping up with early maturers. Late maturing boys take longer relative strides, and have more anteversion of the thigh at heel contact, a smaller knee-angle during swing-phase and a lower mass moment of inertia. CONCLUSION: Running style seems to be an important determinant in running economy of children.

Soil clean up by venting: comparison between modelling and experimental VOC removal results.

Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: fuels (gasoline or gas oil), fuel oil and lubricants. Pollution by petroleum products is a source of volatile organic compounds in soil. Therefore, laboratory column venting experiments were completed in order to investigate the removal of a pure compound (toluene) and a mixture of two (toluene and n-heptane) and five (toluene, n-heptane, ethylbenzene, m-xylene and p-xylene) compounds. The choice of the compounds, as well as their proportion in the mixture was made on the basis of the real fuel composition. The objective of this study is a comparison between the experimental volatile organic compounds removal results and the predicted values of a simple classical analytical mathematical model that enables the modelling of the venting process. The proposed model for the contaminants transport describes the removal of organic compounds from soil, the contaminants being distributed among four phases: vapour, nonaqueous liquid phase, aqueous and "solid" phase; local phases equilibrium and ideal behaviour of all four phases were found to be accurate enough to describe the interphase mass transfer. The testing of the mathematical model accuracy has been done by using the following performance criteria: dynamic absolute error, average error, model accuracy and correlation coefficient. The reasonable agreement between the predicted and the experimental results as well as the values of the performance criteria prove that the mathematical model is suitable to describe the removal of volatile organic compounds pollutants by venting in the range of experimental conditions used in the pilot plant.

A multidisciplinary selection model for youth soccer: the Ghent Youth Soccer Project.

OBJECTIVES: To determine the relationships between physical and performance characteristics and level of skill in youth soccer players aged 12-16 years. METHODS: Anthropometry, maturity status, functional and sport-specific parameters were assessed in elite, sub-elite, and non-elite youth players in four age groups: U13 (n = 117), U14 (n = 136), U15 (n = 138) and U16 (n = 99). RESULTS: Multivariate analyses of covariance by age group with maturity status as the covariate showed that elite players scored better than the non-elite players on strength, flexibility, speed, aerobic endurance, anaerobic capacity and several technical skills (p<0.05). Stepwise discriminant analyses showed that running speed and technical skills were the most important characteristics in U13 and U14 players, while cardiorespiratory endurance was more important in U15 and U16 players. The results suggest that discriminating characteristics change with competitive age levels. CONCLUSIONS: Characteristics that discriminate youth soccer players vary by age group. Talent identification models should thus be dynamic and provide opportunities for changing parameters in a long-term developmental context.

A home-based multidimensional exercise program reduced physical impairment and fear of falling.

OBJECTIVE: To investigate the efficacy of a guided and graded home-based exercise program for improving a range of physical outcomes in older people. DESIGN: Controlled clinical trial of 16 weeks. SETTING: Two geographical areas in Gent, Belgium. PARTICIPANTS: 66 independent-living older people (age: 71-98) with a history of falls and moderate physical impairment. INTERVENTION: Twenty-four 30-minute training sessions were given by a trained physiotherapist over a period of 16 weeks in the participant's home. Different types of exercises on balance, aerobic performance, flexibility, and muscle strength were provided. MAIN OUTCOME MEASURES: Muscle strength, static and dynamic balance, aerobic performance, activities in daily living, fear of falling and avoidance of daily activities were assessed at baseline and after 16 weeks intervention. RESULTS: At baseline, there were no significant differences in the measured variables between exercise and control groups. After 16 weeks, the exercise group showed significantly improved ankle muscle strength, balance performance and aerobic capacity, and decreased fear of falling, dependency in daily activities and avoidance of daily activities compared to the control group. The improvements in knee muscle strength, timed chair stands, and functional reach were not significant. CONCLUSION: The home-based, individualized exercise program was effective in reducing several physical factors associated with falls in community-dwelling older people with moderate physical impairment. The decrease in fear of falling and other behavioural variables needs to be considered with care and needs further investigation.

[Drag-out in metal finishing industries]. / L'entrainement dans les ateliers de traitement de surface.

Currently, environmental regulations induce industrialists to implement source reduction techniques in order to comply with the prevention principle toward sustainable development. The project PIPSI (PIlotage Propre des Systèmes Industriels/industrial system dean piloting) financing by Rhone-Alps Region is carried out with the aim to contribute to this objective. The study presented in this article concerns the pollution transfer in a metal finishing treatment line in order to minimise the environmental impact obtained notably with the pollution balance. Drag-out and draining phenomena have been particularly studied. Results obtained showed that a 10 seconds of draining reduced drag-out from 65 to 85% in terms of pieces design. Moreover, during the experiments, 5 drag-out levels were identified by medium values from 26 to 1700 ml m(-2). So that, either a piece can be associated to a level or knowing the piece drag-out level, it is possible to evaluate its medium drag-out value. Then the pollution balance will be obtained more easily.

Age at menarche in relation to anthropometric characteristics, competition level and boat category in elite junior rowers.

BACKGROUND: Within the context of the effects of training for sports on growth and maturation, there is very little menarcheal data for elite rowing athletes. Knowledge of the relationship of the maturational status with training level, different boat categories, and somatic features of the athletes will clarify the assumed impact of rowing training on the growth and maturational process of youngsters. AIM: The aim of this study was to determine the age at menarche in world top junior rowing athletes and to investigate its relationship with anthropometric characteristics, and competition level, rowing style and boat category. SUBJECTS AND METHODS: The sample consisted of 212 female junior rowers, with a mean chronological age of 17.6 +/- 0.8 years, all participants at the 1997 FISA World Junior Rowing Championships. Anthropometric dimensions, somatotype and body composition characteristics were measured, and age at menarche and training data were retrospectively obtained by questionnaires. RESULTS: Results revealed that the mean age at menarche of the total group of rowers was 12.8 +/- 1.2 years and did not differ from a non-athletic reference population. Rowers who started their rowing training before menarche (n = 78) showed a significant (p

Which factors predict outcome in the treatment program of anterior knee pain?

The goal of this prospective study was to determine the outcome-predictive role of various parameters in the nonoperative treatment of chronic anterior knee pain patients. Thirty patients followed a five-week treatment program, which consisted out of only closed kinetic chain exercises. Prior to this treatment all subjects were evaluated on muscular characteristics, subjective symptoms, weight, sex, duration of symptoms and functional performance. A multiple stepwise regression analysis revealed that the reflex response time of m. vastus medialis obliquus (VMO) (P=0.041; 0.026), and the duration of symptoms (P=0.019; 0.045) were the only two parameters which were significantly associated with the outcome (evaluated by the Kujala score) at five weeks, and at three months. The shorter the duration of symptoms, or the faster the reflex response time of VMO prior to the treatment, the better the outcome after a closed kinetic chain exercise program. The statistical significance of these parameters in this study may be seen as an indication of the importance of these variables as predictors of the outcome of a closed kinetic chain strengthening program. Using this information, it seems clinically important to begin the treatment program before the anterior knee pain becomes more chronic and treatment results become less good.

Kinetics of light emission and oxygen consumption by bioluminescent bacteria.

Oxygen plays a key role in bacterial bioluminescence. The simultaneous and continuous kinetics of oxygen consumption and light emission during a complete exhaustion of the exogenous oxygen present in a closed system has been investigated. The kinetics are performed with Vibrio fischeri, V. harveyi, and Photobacterium phosphoreum incubated on respiratory substrates chosen for their different reducing power. The general patterns of the luminescence time courses are different among species but not among substrates. During steady-state conditions, substrates, which are less reduced than glycerol, have, paradoxally, a better luminescence efficiency. Oxygen consumption by luciferase has been evaluated to be approximately 17% of the total respiration. Luciferase is a regulatory enzyme presenting a positive cooperative effect with oxygen and its affinity for this final electron acceptor is about 4-5 times higher than the one of cytochrome oxidase. The apparent Michaelis constant for luciferase has been evaluated to be in the range of 20 to 65 nM O2. When O2 concentrations are as low as 10 nM, luminescence can still be detected; this means that above this concentration, strict anaerobiosis does not exist. By n-butyl malonate titration, it was clearly shown that electrons enter the luciferase pathway only when the cytochrome pathway is saturated. It is suggested that, in bioluminescent bacteria, luciferase acts as a free-energy dissipating valve when anabolic processes (biomass production) are impaired.

Effects of three different training modalities on the cross sectional area of the lumbar multifidus muscle in patients with chronic low back pain.

OBJECTIVES: To determine the effect of different training schedules on the cross sectional area (CSA) of the lumbar multifidus muscle in patients with chronic low back pain. METHODS: Each of 59 nine patients was randomly assigned to one of three programmes: 10 weeks of stabilisation training (group 1; n = 19); 10 weeks of stabilisation training combined with dynamic resistance training (group 2; n = 20); 10 weeks of stabilisation training combined with dynamic-static resistance training (group 3; n = 20). Before and after 10 weeks of training, multifidus CSAs were measured from standard computed tomography images at three different levels (upper end plate of L3 and L4, and lower end plate of L4). RESULTS: The CSA of the multifidus muscle was significantly increased at all levels after training in group 3. In contrast, no significant differences were found in groups 1 and 2. CONCLUSIONS: General stabilisation exercises and dynamic intensive lumbar resistance training have no significant effect on the CSA of the lumbar multifidus muscle in patients with chronic low back pain. The static holding component between the concentric and eccentric phase was found to be critical in inducing muscle hypertrophy during the first 10 weeks. Treatment consisting of stabilisation training combined with an intensive lumbar dynamic-static strengthening programme seems to be the most appropriate method of restoring the size of the multifidus muscle.

Anthropometric characteristics of elite female junior rowers.

During the 1997 Federation Internationale des Sociétés d'Aviron (FISA) World Junior Rowing Championships, the anthropometric characteristics of 245 female junior rowers aged 17.5 +/- 0.8 years (mean +/- s) were assessed. Twenty-seven body dimensions (body mass, 6 heights or lengths, 4 breadths, 10 girths and 6 skinfolds) were measured in total. The elite female junior rowers were taller (174.5 +/- 6.2 cm) and heavier (69.5 +/- 6.2 kg), with greater length, breadth and girth dimensions, but lower skinfold thicknesses than a representative sample of Flemish (Belgian) girls of the same chronological age. An anthropometric profile chart was constructed that was rowing-specific and norms were established. Compared with scullers, sweep rowers were heavier (+4.2 kg) and taller (+2.8 cm), with greater length, breadth (except for femur width) and girth dimensions (except for calf girth). Sweep rowers also had greater skinfold thicknesses (except for the thigh and calf skinfolds). Finalists were heavier (+3.6 kg) and taller (+3.9 cm), with greater length, breadth (except for femur width) and girth dimensions (except for calf girth) than non-finalists. No significant differences were found for skinfold thicknesses between finalists and non-finalists.

The effects of three different training modalities on the cross-sectional area of the paravertebral muscles.

The purpose of this study was to determine the effect of different training schedules on the cross-sectional area (CSA) of the paravertebral muscles (PA) in chronic low back pain (CLBP) patients. To achieve this goal 59 patients were randomly assigned to three different 10-week rehabilitation programs: stabilization training (group 1, n=19), stabilization training combined with dynamic resistance training (group 2, n=20) and stabilization training combined with dynamic-static resistance training (group 3, n=20). The CSA of the PA was derived from standard computerized tomography (CT) images at three different levels. The CSA of the PA was found to increase statistically in group 2 (upper end-plate of L4) and group 3 (upper end-plate of L3 and lower end-plate of L4). In contrast, no statistical differences over time were found in group 1. Since stabilization exercises have no effect on the CSA of the PA, intensive lumbar resistance training seems to be necessary to restore the size of the PA in CLBP patients with atrophied back muscles. No systematic difference in hypertrophy between dynamic and dynamic-static strengthening training modes was found.

Anthropometric characteristics of elite male junior rowers.

During the 1997 Federation Internationale des Sociétés d'Aviron World Junior Rowing Championships, anthropometric data on 383 male junior rowers were assessed. With 430 participating athletes, the sample represented 89% of the population. In addition to age, 27 dimensions were measured: body mass, six heights or lengths, four breadths, 10 girths, and six skinfolds. The elite male junior rowers were tall (187.4 (5.8) cm; mean (SD)) and heavy (82.2 (7.4) kg), with larger length, breadth, and girth dimensions than a nationally representative sample of Belgian boys of the same chronological age. A rowing specific anthropometric profile chart with norms was constructed. The stature of the junior rowers is similar to that of adult heavyweight elite rowers, except that the junior rowers are lighter. Compared with non-finalists, finalists are heavier (but still lighter than the adult heavyweight elite rower) and taller, with greater length, breadth (except for the bicristal diameter), and girth dimensions.

Metabolic and cardiorespiratory responses in young oarsmen during prolonged exercise tests on a rowing ergometer at power outputs corresponding to two concepts of anaerobic threshold.

A group of ten young experienced oarsmen [mean age 17.5 (SD 1.7) years, height 182.5 (SD 5.9) cm, body mass 77.0 (SEM 10.6) kg] exercised in a progressive incremental test (PIE: 50W x 3 min[-1]) on a rowing ergometer to determine the power output corresponding to the 4 mmol lactate x l(-1) anaerobic threshold (AT4) and the individual anaerobic threshold (IAT). Within 10 days they performed at random two 30-min prolonged exercise tests (PET) at power outputs corresponding to AT4 and IAT to demonstrate whether or not a steady-state blood lactate concentration [La-]b could be maintained. Oxygen uptake (VO2), heart rate (HR) and [La-]b were measured. The PIE revealed significant lower values at IAT compared to AT4 for power output (P < 0.01), HR (P < 0.01) and VO2 (P < 0.01). Coefficients of correlation between AT4 and IAT were 0.68 for power output, 0.79 for HR and 0.70 for VO2. All the subjects could complete the PET at IAT and only six out of the ten at AT4. The [La-]b at the end of PET was significantly higher at AT4 compared to IAT (P < 0.01). Similar results were found for VO2 (P < 0.01) and for HR (P < 0.01). A steady state of mean blood lactate concentration ([La-]ss was found only for the power output at IAT. From the results of this study, we concluded that both concepts of anaerobic threshold gave different information about submaximal endurance capacity. Only IAT represented on average [La-]ss. It is suggested that more research is needed to elicit optimal guidelines for the intensity of endurance training.