International Journal of Environmental Research and Public Health
The purpose of this study was to investigate blood-based biomarkers and their regulation with reg... more The purpose of this study was to investigate blood-based biomarkers and their regulation with regard to different recovery-stress states. A total of 35 male elite athletes (13 badminton, 22 soccer players) were recruited, and two venous blood samples were taken: one in a ‘recovered’ state (REC) after a minimum of one-day rest from exercise and another one in a ‘non-recovered’ state (NOR) after a habitual loading microcycle. Overall, 23 blood-based biomarkers of different physiologic domains, which address inflammation, muscle damage, and tissue repair, were analyzed by Luminex assays. Across all athletes, only creatine kinase (CK), interleukin (IL-) 6, and IL-17A showed higher concentrations at NOR compared to REC time points. In badminton players, higher levels of CK and IL-17A at NOR were found. In contrast, a higher value for S100 calcium-binding protein A8 (S100A8) at REC was found in badminton players. Similar differences were found for BDNF in soccer players. Soccer players al...
This article critically examines the execution of VO(2)-peak testing in cardiac patients and ques... more This article critically examines the execution of VO(2)-peak testing in cardiac patients and questions their appropriate interpretation. In the first part, the most common clinical implications of VO(2)peak measurements are discussed: assessment of (changes in) functional capacity, evaluation of the necessity of invasive diagnostic/therapeutic measures, reference for exercise prescriptions, determination of prognosis. In the second part, important methodological problems and constraints are addressed and illustrated by references to scientific studies. Finally, recommendations are given for meaningful VO(2)peak testing. It is evident that failure to strictly follow such recommendations might result in misleading ergometric findings and, thus, in over- or underestimation of endurance capacity and/ or training effects.
Key Performance Indicators (KPIs) are used to evaluate the offensive success of a soccer team (e.... more Key Performance Indicators (KPIs) are used to evaluate the offensive success of a soccer team (e.g. penalty box entries) or player (e.g. pass completion rate). However, knowledge transfer from research to applied practice is understudied. The current study queried practitioners (n = 145, mean ± SD age: 36 ± 9 years) from 42 countries across different roles and levels of competition (National Team Federation to Youth Academy levels) on various forms of data collection, including an explicit assessment of twelve attacking KPIs. 64.3% of practitioners use data tools and applications weekly (predominately) to gather KPIs during matches. 83% of practitioners use event data compared to only 52% of practitioners using positional data, with a preference for shooting related KPIs. Differences in the use and value of metrics derived from positional tracking data (including Ball Possession Metrics) were evident between job role and level of competition. These findings demonstrate that practiti...
The purpose of this study was to investigate blood-based biomarkers and their regulation with reg... more The purpose of this study was to investigate blood-based biomarkers and their regulation with regard to different recovery-stress states. A total of 35 male elite athletes (13 badminton, 22 soccer players) were recruited, and two venous blood samples were taken: one in a ‘recovered’ state (REC) after a minimum of one-day rest from exercise and another one in a ‘non-recovered’ state (NOR) after a habitual loading microcycle. Overall, 23 blood-based biomarkers of different physiologic domains, which address inflammation, muscle damage, and tissue repair, were analyzed by Luminex assays. Across all athletes, only creatine kinase (CK), interleukin (IL-) 6, and IL-17A showed higher concentrations at NOR compared to REC time points. In badminton players, higher levels of CK and IL-17A at NOR were found. In contrast, a higher value for S100 calcium-binding protein A8 (S100A8) at REC was found in badminton players. Similar differences were found for BDNF in soccer players. Soccer players al...
ABSTRACT Objectives Influenza vaccination was used to assess whether induction of immunity or sid... more ABSTRACT Objectives Influenza vaccination was used to assess whether induction of immunity or side effects are influenced by the timing of the last training session before vaccination. Methods Forty-five healthy athletes (36 male, 23 ± 8 yr, ≥5 training sessions per week, predominantly national competition level) were vaccinated with the tetravalent influenza vaccine; blood samples were collected immediately before and 1, 2, and 26 wk after vaccination. Athletes were randomly assigned to vaccination within 2 h after the last training session versus after 24–26 h. Influenza-specific T cells were quantified after stimulation with the vaccine based on intracellular cytokine staining. Antibodies (IgA, IgG, IgM) were quantified by enzyme-linked immunosorbent assay and neutralization assay. Participants documented resulting side effects and training restrictions using a standardized diary. Results Both groups showed an increase in influenza-reactive CD4 T-cell levels, which peaked 1 wk after vaccination (fold changes to baseline; median (interquartile range), 3.7 (3.0–5.4; P < 0.001) in the 2-h group; 4.6 (2.8–7.4; P < 0.001) in the 26-h group) with no difference between groups (P = 0.52). Influenza-specific antibodies showed a significant increase after vaccination in both groups (at least 1.4-fold, each P < 0.001, no group differences; P = 0.24–0.97 for different antibody types). Only antibodies toward the Brisbane strain showed a trend toward significant differences in neutralization titers between groups (4-fold (2–17.8) in the 2-h group, 16-fold (4–32.9) in the 26-h group; P = 0.06), whereas other specificities did not differ (P = 0.16–0.72). No intergroup differences were found for side effects; no athlete reported a loss of training time due to the vaccination or its side effects. Conclusion Infection prophylaxis in elite athletes by influenza vaccination seems to be effective and safe. Timing of vaccination after prior training does not seem to require specific constraints.
Research in football for a long time has focused on the physical nature of fatigue as opposed to ... more Research in football for a long time has focused on the physical nature of fatigue as opposed to its mental aspects. However, since 2016, six original articles have investigated the effects of induced mental fatigue in football on isolated physical, skill and decision-making performance tests, along with physical, technical and tactical performance outcomes in small-sided games. Whilst these studies have overall shown a negative impact of mental fatigue on task performance, this current opinion aims to critically examine the methodological approach to this problem, most notably the lack of ecological validity when inducing mental fatigue and the present approach to measuring mental fatigue using visual analogue scales (VAS). It is suggested that future research on mental fatigue in football may benefit from the use of surveys/interviews to understand the true cognitive demands of elite football players. Additionally, future research should aim to reduce the reliance on using VAS to measure mental fatigue as results from this tool may be confounded by several response biases. In conclusion, this article highlights the need for mentally fatiguing tasks that adequately represent football-associated mental fatigue and assessments of mental fatigue that minimise the confounding effect of response bias.
Many publications about the treatment and return to play after severe football injuries are avail... more Many publications about the treatment and return to play after severe football injuries are available from the scientific literature, particularly about injuries requiring surgery. In contrast, less severe football injuries, such as muscle strains, ankle sprains and contusions, are less well addressed in the literature although these represent the most frequent type of injury. Additionally, such reports often have a low level of evidence and guidelines on treatment and the return to play process are very rare. Thus, the time away from football and the timing of return to play after minor injuries depends on the experience and skills of the responsible medical team. To achieve the aim of stay and play on the field, the medical team should be highly knowledgeable in interdisciplinary football medicine, prevention strategies, first aid on the field, clinical and manual diagnostics, tissue regeneration, symptomatic and conservative treatment as well as in return to play decision-making....
A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an a... more A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an athlete's individual responses to training to optimize the scheduling of training and recovery strategies. Resting and exercise-related heart rate measures have received growing interest in recent decades and are considered potentially useful within multivariate response monitoring, as they provide non-invasive and time-efficient insights into the status of the autonomic nervous system (ANS) and aerobic fitness. In team sports, the practical implementation of athlete monitoring systems poses a particular challenge due to the complex and multidimensional structure of game demands and player and team performance, as well as logistic reasons, such as the typically large number of players and busy training and competition schedules. In this regard, exercise-related heart rate measures are likely the most applicable markers, as they can be routinely assessed during warm-ups using short (3-...
Fatigue is a complex state with multiple physiological and psychological origins. However, fatigu... more Fatigue is a complex state with multiple physiological and psychological origins. However, fatigue in soccer has traditionally been investigated from a physiological perspective, with little emphasis on the cognitive demands of competition. These cognitive demands may induce mental fatigue, which could contribute to the fatigue-related performance decrements observed during and after soccer matches. Recent research investigating the relationship between mental fatigue and soccer-specific performance supports this suggestion. This leading article provides an overview of the research in this emerging field, outlining the impact of mental fatigue on soccer-specific physical, technical, decision-making, and tactical performances. The second half of this review provides directions for future research in response to the limitations of the existing research. Emphasis is placed on translating the current body of knowledge into practical applications and developing a greater understanding of...
Money has frequently been used as an extrinsic motivator since it is assumed that humans are will... more Money has frequently been used as an extrinsic motivator since it is assumed that humans are willing to invest more effort for financial reward. However, the influence of a monetary reward on pacing and performance in trained athletes is not well-understood. Therefore, the aim of this study was to analyse the influence of a monetary reward in well-trained cyclists on their pacing and performance during short and long cycling time trials (TT). Twentythree cyclists (6 ♀, 17 ♂) completed 4 self-paced time trials (TTs, 2 short: 4 km and 6 min; 2 long: 20 km and 30 min); in a randomized order. Participants were separated into parallel, non-randomized "rewarded" and "non-rewarded" groups. Cyclists in the rewarded group received a monetary reward based on highest mean power output across all TTs. Cyclists in the non-rewarded group did not receive a monetary reward. Overall performance was not significantly different between groups in short or long TTs (p > 0.48). Pow...
This study examined sleep-wake habits and subjective jet-lag ratings of 55 German junior rowers (... more This study examined sleep-wake habits and subjective jet-lag ratings of 55 German junior rowers (n = 30 male, 17.8 ± 0.5 years) before and during the World Rowing Junior Championships 2015 in Rio de Janeiro, Brazil. Athletes answered sleep logs every morning, and Liverpool John Moore's University Jet-Lag Questionnaires each evening and morning. Following an 11-h westward flight with 5-h time shift, advanced bedtimes (-1 h, P < .001, ηp(2) = 0.68), reduced sleep onset latency (P = .002, ηp(2) = 0.53) and increased sleep duration (P < .001, ηp(2) = 0.60) were reported for the first two nights. Jet-lag symptoms peaked upon arrival but were still present after 6 days. Sleep quality improved (P < .001, ηp(2) = 0.31) as well as some scales of the Recovery-Stress Questionnaire for Athletes. Participation was successful as indicated by 11 of 13 top 3 placings. Overall, the initial desynchronisation did not indicate negative impacts on competition performance. As travel fatigue ...
The Acute Recovery and Stress Scale (ARSS) and the Short Recovery and Stress Scale were first est... more The Acute Recovery and Stress Scale (ARSS) and the Short Recovery and Stress Scale were first established in German for the purposes of monitoring athletes' current recovery-stress states in an economical and multidimensional manner. The aim of this paper is to document the development and initial validation of the English versions of these two psychometric monitoring tools. A total of 267 English-speaking athletes from a variety of team and individual sports participated in the study. The English versions demonstrated satisfactory internal consistency for both instruments (Cronbach α of .74-.89). Furthermore, good model fit was found for the eight scales of the ARSS, matching the structure and results of the German counterparts. Correlations among and between the scales reciprocate the theoretical constructs of stress and recovery, supporting the construct validity of the scales. Correlation coefficients within stress and recovery ranged between rs = .29 and .68. The correlatio...
International Journal of Environmental Research and Public Health
The purpose of this study was to investigate blood-based biomarkers and their regulation with reg... more The purpose of this study was to investigate blood-based biomarkers and their regulation with regard to different recovery-stress states. A total of 35 male elite athletes (13 badminton, 22 soccer players) were recruited, and two venous blood samples were taken: one in a ‘recovered’ state (REC) after a minimum of one-day rest from exercise and another one in a ‘non-recovered’ state (NOR) after a habitual loading microcycle. Overall, 23 blood-based biomarkers of different physiologic domains, which address inflammation, muscle damage, and tissue repair, were analyzed by Luminex assays. Across all athletes, only creatine kinase (CK), interleukin (IL-) 6, and IL-17A showed higher concentrations at NOR compared to REC time points. In badminton players, higher levels of CK and IL-17A at NOR were found. In contrast, a higher value for S100 calcium-binding protein A8 (S100A8) at REC was found in badminton players. Similar differences were found for BDNF in soccer players. Soccer players al...
This article critically examines the execution of VO(2)-peak testing in cardiac patients and ques... more This article critically examines the execution of VO(2)-peak testing in cardiac patients and questions their appropriate interpretation. In the first part, the most common clinical implications of VO(2)peak measurements are discussed: assessment of (changes in) functional capacity, evaluation of the necessity of invasive diagnostic/therapeutic measures, reference for exercise prescriptions, determination of prognosis. In the second part, important methodological problems and constraints are addressed and illustrated by references to scientific studies. Finally, recommendations are given for meaningful VO(2)peak testing. It is evident that failure to strictly follow such recommendations might result in misleading ergometric findings and, thus, in over- or underestimation of endurance capacity and/ or training effects.
Key Performance Indicators (KPIs) are used to evaluate the offensive success of a soccer team (e.... more Key Performance Indicators (KPIs) are used to evaluate the offensive success of a soccer team (e.g. penalty box entries) or player (e.g. pass completion rate). However, knowledge transfer from research to applied practice is understudied. The current study queried practitioners (n = 145, mean ± SD age: 36 ± 9 years) from 42 countries across different roles and levels of competition (National Team Federation to Youth Academy levels) on various forms of data collection, including an explicit assessment of twelve attacking KPIs. 64.3% of practitioners use data tools and applications weekly (predominately) to gather KPIs during matches. 83% of practitioners use event data compared to only 52% of practitioners using positional data, with a preference for shooting related KPIs. Differences in the use and value of metrics derived from positional tracking data (including Ball Possession Metrics) were evident between job role and level of competition. These findings demonstrate that practiti...
The purpose of this study was to investigate blood-based biomarkers and their regulation with reg... more The purpose of this study was to investigate blood-based biomarkers and their regulation with regard to different recovery-stress states. A total of 35 male elite athletes (13 badminton, 22 soccer players) were recruited, and two venous blood samples were taken: one in a ‘recovered’ state (REC) after a minimum of one-day rest from exercise and another one in a ‘non-recovered’ state (NOR) after a habitual loading microcycle. Overall, 23 blood-based biomarkers of different physiologic domains, which address inflammation, muscle damage, and tissue repair, were analyzed by Luminex assays. Across all athletes, only creatine kinase (CK), interleukin (IL-) 6, and IL-17A showed higher concentrations at NOR compared to REC time points. In badminton players, higher levels of CK and IL-17A at NOR were found. In contrast, a higher value for S100 calcium-binding protein A8 (S100A8) at REC was found in badminton players. Similar differences were found for BDNF in soccer players. Soccer players al...
ABSTRACT Objectives Influenza vaccination was used to assess whether induction of immunity or sid... more ABSTRACT Objectives Influenza vaccination was used to assess whether induction of immunity or side effects are influenced by the timing of the last training session before vaccination. Methods Forty-five healthy athletes (36 male, 23 ± 8 yr, ≥5 training sessions per week, predominantly national competition level) were vaccinated with the tetravalent influenza vaccine; blood samples were collected immediately before and 1, 2, and 26 wk after vaccination. Athletes were randomly assigned to vaccination within 2 h after the last training session versus after 24–26 h. Influenza-specific T cells were quantified after stimulation with the vaccine based on intracellular cytokine staining. Antibodies (IgA, IgG, IgM) were quantified by enzyme-linked immunosorbent assay and neutralization assay. Participants documented resulting side effects and training restrictions using a standardized diary. Results Both groups showed an increase in influenza-reactive CD4 T-cell levels, which peaked 1 wk after vaccination (fold changes to baseline; median (interquartile range), 3.7 (3.0–5.4; P < 0.001) in the 2-h group; 4.6 (2.8–7.4; P < 0.001) in the 26-h group) with no difference between groups (P = 0.52). Influenza-specific antibodies showed a significant increase after vaccination in both groups (at least 1.4-fold, each P < 0.001, no group differences; P = 0.24–0.97 for different antibody types). Only antibodies toward the Brisbane strain showed a trend toward significant differences in neutralization titers between groups (4-fold (2–17.8) in the 2-h group, 16-fold (4–32.9) in the 26-h group; P = 0.06), whereas other specificities did not differ (P = 0.16–0.72). No intergroup differences were found for side effects; no athlete reported a loss of training time due to the vaccination or its side effects. Conclusion Infection prophylaxis in elite athletes by influenza vaccination seems to be effective and safe. Timing of vaccination after prior training does not seem to require specific constraints.
Research in football for a long time has focused on the physical nature of fatigue as opposed to ... more Research in football for a long time has focused on the physical nature of fatigue as opposed to its mental aspects. However, since 2016, six original articles have investigated the effects of induced mental fatigue in football on isolated physical, skill and decision-making performance tests, along with physical, technical and tactical performance outcomes in small-sided games. Whilst these studies have overall shown a negative impact of mental fatigue on task performance, this current opinion aims to critically examine the methodological approach to this problem, most notably the lack of ecological validity when inducing mental fatigue and the present approach to measuring mental fatigue using visual analogue scales (VAS). It is suggested that future research on mental fatigue in football may benefit from the use of surveys/interviews to understand the true cognitive demands of elite football players. Additionally, future research should aim to reduce the reliance on using VAS to measure mental fatigue as results from this tool may be confounded by several response biases. In conclusion, this article highlights the need for mentally fatiguing tasks that adequately represent football-associated mental fatigue and assessments of mental fatigue that minimise the confounding effect of response bias.
Many publications about the treatment and return to play after severe football injuries are avail... more Many publications about the treatment and return to play after severe football injuries are available from the scientific literature, particularly about injuries requiring surgery. In contrast, less severe football injuries, such as muscle strains, ankle sprains and contusions, are less well addressed in the literature although these represent the most frequent type of injury. Additionally, such reports often have a low level of evidence and guidelines on treatment and the return to play process are very rare. Thus, the time away from football and the timing of return to play after minor injuries depends on the experience and skills of the responsible medical team. To achieve the aim of stay and play on the field, the medical team should be highly knowledgeable in interdisciplinary football medicine, prevention strategies, first aid on the field, clinical and manual diagnostics, tissue regeneration, symptomatic and conservative treatment as well as in return to play decision-making....
A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an a... more A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an athlete's individual responses to training to optimize the scheduling of training and recovery strategies. Resting and exercise-related heart rate measures have received growing interest in recent decades and are considered potentially useful within multivariate response monitoring, as they provide non-invasive and time-efficient insights into the status of the autonomic nervous system (ANS) and aerobic fitness. In team sports, the practical implementation of athlete monitoring systems poses a particular challenge due to the complex and multidimensional structure of game demands and player and team performance, as well as logistic reasons, such as the typically large number of players and busy training and competition schedules. In this regard, exercise-related heart rate measures are likely the most applicable markers, as they can be routinely assessed during warm-ups using short (3-...
Fatigue is a complex state with multiple physiological and psychological origins. However, fatigu... more Fatigue is a complex state with multiple physiological and psychological origins. However, fatigue in soccer has traditionally been investigated from a physiological perspective, with little emphasis on the cognitive demands of competition. These cognitive demands may induce mental fatigue, which could contribute to the fatigue-related performance decrements observed during and after soccer matches. Recent research investigating the relationship between mental fatigue and soccer-specific performance supports this suggestion. This leading article provides an overview of the research in this emerging field, outlining the impact of mental fatigue on soccer-specific physical, technical, decision-making, and tactical performances. The second half of this review provides directions for future research in response to the limitations of the existing research. Emphasis is placed on translating the current body of knowledge into practical applications and developing a greater understanding of...
Money has frequently been used as an extrinsic motivator since it is assumed that humans are will... more Money has frequently been used as an extrinsic motivator since it is assumed that humans are willing to invest more effort for financial reward. However, the influence of a monetary reward on pacing and performance in trained athletes is not well-understood. Therefore, the aim of this study was to analyse the influence of a monetary reward in well-trained cyclists on their pacing and performance during short and long cycling time trials (TT). Twentythree cyclists (6 ♀, 17 ♂) completed 4 self-paced time trials (TTs, 2 short: 4 km and 6 min; 2 long: 20 km and 30 min); in a randomized order. Participants were separated into parallel, non-randomized "rewarded" and "non-rewarded" groups. Cyclists in the rewarded group received a monetary reward based on highest mean power output across all TTs. Cyclists in the non-rewarded group did not receive a monetary reward. Overall performance was not significantly different between groups in short or long TTs (p > 0.48). Pow...
This study examined sleep-wake habits and subjective jet-lag ratings of 55 German junior rowers (... more This study examined sleep-wake habits and subjective jet-lag ratings of 55 German junior rowers (n = 30 male, 17.8 ± 0.5 years) before and during the World Rowing Junior Championships 2015 in Rio de Janeiro, Brazil. Athletes answered sleep logs every morning, and Liverpool John Moore's University Jet-Lag Questionnaires each evening and morning. Following an 11-h westward flight with 5-h time shift, advanced bedtimes (-1 h, P < .001, ηp(2) = 0.68), reduced sleep onset latency (P = .002, ηp(2) = 0.53) and increased sleep duration (P < .001, ηp(2) = 0.60) were reported for the first two nights. Jet-lag symptoms peaked upon arrival but were still present after 6 days. Sleep quality improved (P < .001, ηp(2) = 0.31) as well as some scales of the Recovery-Stress Questionnaire for Athletes. Participation was successful as indicated by 11 of 13 top 3 placings. Overall, the initial desynchronisation did not indicate negative impacts on competition performance. As travel fatigue ...
The Acute Recovery and Stress Scale (ARSS) and the Short Recovery and Stress Scale were first est... more The Acute Recovery and Stress Scale (ARSS) and the Short Recovery and Stress Scale were first established in German for the purposes of monitoring athletes' current recovery-stress states in an economical and multidimensional manner. The aim of this paper is to document the development and initial validation of the English versions of these two psychometric monitoring tools. A total of 267 English-speaking athletes from a variety of team and individual sports participated in the study. The English versions demonstrated satisfactory internal consistency for both instruments (Cronbach α of .74-.89). Furthermore, good model fit was found for the eight scales of the ARSS, matching the structure and results of the German counterparts. Correlations among and between the scales reciprocate the theoretical constructs of stress and recovery, supporting the construct validity of the scales. Correlation coefficients within stress and recovery ranged between rs = .29 and .68. The correlatio...
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Papers by Tim Meyer