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Purpose: To (1) examine within-individual player dose–response associations between selected training-load measures and changes in aerobic fitness level via submaximal exercise heart rate (HRex%) and (2) measure the relationships between these dose–response associations with basal HRex% (to study the influence of fitness level on dose–response relationship). Methods: During an in-season phase, selected training-load measures including total minutes, total distance, mechanical work (the sum number of accelerations and decelerations > 3 m2), high metabolic load distance, and Edwards' training impulse were collected via Global Positioning System and heart-rate sensors for analyzing accumulated load. A submaximal warm-up test was used repeatedly before and after 9 phases to elicit HRex% and track fitness changes at an individual level. Results: Negative to positive extensive ranges of within-individual associations were found among players for different metrics (r = −.84 to.89). The relationship between pooled HRex% (basal fitness) and dose–response correlations showed inverse very large (r = −.71) and large (r = −.65) values for accumulated weekly minutes and distance. However, moderate values were found for all other measures (r = −.35 to −.42). Conclusions: Individual players show extensive different ranges of dose–response associations with training measures. The dose–response association is influenced by players' fitness level, and players with lower fitness levels show stronger inverse relationships with accumulated minutes and total distance. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were to examine the variability of selected external load metrics within 15-minute intervals during soccer match play and examine their relationship with players' high-intensity intermittent fitness. Methods: A total of 18 male soccer players were monitored for their external load metrics during 26 matches, which included total distance, high-metabolic-load distance, and mechanical work (defined as the sum of accelerations and decelerations >3 m2). Additionally, players completed the 30-15 Intermittent Fitness Test. Results: Total distance had lower coefficients of variation than high-metabolic-load distance and mechanical work (effect size [ES]: 5.2 to 6.4; very large). Within-player Δ-15min showed moderate to large decreases (ES: −0.7 to −1.6) and increases (ES: 0.9 to 1.8) in absolute and coefficient-of-variation values, respectively. Large relationships (r =.55 to.61) were observed between the Intermittent Fitness Test and 15-minmean and 15-minbest in all selected external load metrics. However, small to moderate (0.27 to 0.41) associations were observed between the Intermittent Fitness Test and Δ-15min in selected external load metrics. Conclusions: These findings suggest that players with relatively lower intermittent running capacity might show lower variability during matches, as evidenced by smaller reductions in high-intensity actions during the final 15 minutes. We attribute these observations to players' possessing better pacing strategies. [ABSTRACT FROM AUTHOR]

New training approaches have emerged advocating for the implementation of compensatory physical training. This approach aims to provide additional training that balances the load typically experienced by non-starters during a match. This may help maintain their readiness and ensures that their physical fitness is not compromised by the reduced exposure to match loads. Thus, this narrative review aims to describe the differences in external loads between starting and non-starting players and describe the studies conducted in compensatory training. Studies examining external load metrics such as total distances covered, high-speed running, and sprinting suggest that, adjusted for playing time, values are often higher in non-starting players. Although not standardized, there is an obvious decrease in exposure for these critical variables in non-starters. Additionally, internal load parameters such as perceived exertion and heart rate tend to be higher in starting players. Regarding the physical fitness impacts, evidence suggests differences observed between starters and non-starters in some aspects of physical performance, although the extent and significance of these differences can vary. The studies on compensatory training are limited, and the typical approach usually centres on running-based exercises and small-sided games, offering differing approaches to address the physical needs. The gap in research underscores the necessity for improved study designs that can shed light on the real impact of compensatory training. Presently, the practice of compensatory training has been adopted, yet a definitive understanding of its genuine influence, particularly in terms of enhancing physical fitness and mitigating injury risks, remains elusive. [ABSTRACT FROM AUTHOR]

The COVID-19 lockdown challenged the training options of athletes worldwide, including players from the most popular sport globally, football/soccer. Purpose: The authors explored the training practices of football players worldwide during the COVID-19 lockdown. Methods: Football players (N = 2482, 30% professional, 22% semipro, and 48% amateur) completed an online survey (May–July 2020) on their training practices before versus during lockdown (March–June 2020). Questions were related to training frequency and session duration, as well as training knowledge and attitudes. Results: Before lockdown, more professional (87%) than semipro (67%) and amateur (65%) players trained ≥5 sessions/wk, but this proportion decreased during the lockdown to 55%, 35%, and 42%, respectively. Players (80%–87%) trained ≥60 minutes before lockdown, but this proportion decreased to 45% in professionals, 43% in amateurs, and 36% in semipros during lockdown. At home, more than two-thirds of players had training space (73%) and equipment (66%) for cardiorespiratory training, while availability of equipment for technical and strength training was <50% during lockdown. Interactions between coach/trainer and player were more frequent (ie, daily) among professional (27%) than amateur (11%) and semipro (17%) players. Training load monitoring, albeit limited, was mostly performed by fitness coaches, more so with professionals (35%) than amateurs (13%) and semipros (17%). The players' training knowledge and attitudes/beliefs toward training were relatively modest (50%–59%). Conclusion: COVID-19 lockdown negatively affected training practices of football players worldwide, especially amateurs and semipros, for example, in training frequency, duration, intensity, technical, recovery, and other fitness training and coaching-related aspects. During lockdown-like situations, players should be monitored closely and provided appropriate support to facilitate their training. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationship between accumulated global positioning system-accelerometer-based and heart ratebased training metrics and changes in high-intensity intermittent-running capacity during an in-season phase in professional soccer players. Methods: Eleven male professional players (mean [SD] age 27.2 [4.5] y) performed the 30-15 Intermittent Fitness Test (30-15IFT) before and after a 5-wk in-season training phase, and the final velocity (VIFT) was considered their high-intensity intermittent-running capacity. During all sessions, Edwards training impulse (Edwards TRIMP), Banister TRIMP, Z5 TRIMP, training duration, total distance covered, new body load (NBL), high-intensity running performance (distance covered above 14.4 km ⋅h-1), and very-high-intensity running performance (distance covered above 19.8 km⋅h-1) were recorded. Results: The players' VIFT showed a most likely moderate improvement (+4.3%, 90% confidence limits 3.1-5.5%, effect size 0.70, [0.51-0.89]). Accumulated NBL, Banister TRIMP, and Edwards TRIMP showed large associations (r = .51 -.54) with changes in VIFT. A very large relationship was also observed between accumulated Z5 TRIMP (r = .72) with changes in VIFT. Large to nearly perfect within-individual relationships were observed between NBL and some of the other training metrics (ie, Edwards TRIMP, Banister TRIMP, training duration, and total distance) in 10 out of 11 players. Conclusions: Heart rate-based training metrics can be used to monitor high-intensity intermittent-running-capacity changes in professional soccer players. The dose-response relationship is also largely detected using accelerometer-based metrics (ie, NBL) to track changes in high-intensity intermittentrunning capacity of professional soccer players. [ABSTRACT FROM AUTHOR]

This study compared the relative physical demands of official matches and sided games (medium and large) in professional soccer players by means of a global positioning system. Twenty-three professional male soccer players (24.632.84 years old; 180.946.49 cm; 77.196.46 kg; 52.995.01 VO2max) participated in the study. Total distance, running distance, sprinting distance, number of sprints, and acceleration sum were quantified per minute to compare the different games. Running distance in full match was greater than in 5vs5+GK (d = 2.303, moderate effect), 6vs6+GK (d = 1.719, moderate effect) and 9vs9+GK (d = 1.084, minimum effect) sided games. Greater values for sprinting distance were found in the full match compared to 5vs5+GK (d = 3.673, strong effect), 6vs6+GK (d = 2.606, moderate effect) and 9vs9+GK (d = 1.903, moderate effect) sided games. However, the load was greater in the 5vs5+GK game compared to the 6vs6+GK (d = 1.323, moderate effect) and 9vs9+GK (d = 1.030, minimum effect) games and the full match (d = 1.478, moderate effect). This study revealed that medium-sided games are not appropriate for simulating the sprinting conditions of official full matches. However, medium-sided games are more intense than full matches in that accelerations are made more often in medium-sided games. [ABSTRACT FROM AUTHOR]

The aims of this study were to: 1) compare the effects of speed-based versus heart-rate-based high-intensity interval training (HIIT) on changes in high-intensity intermittent running performance, and 2) examine the between-group differences in heart rate (HR) and rating of perceived exertion (RPE) responses during the training sessions. Sixteen female students were divided into the HR-based (n=8, M±SD, age 17.3±0.2 years, body mass, 59.2±5.7 kg, and body height, 167.8±2.2 cm) and speed-based (n=8, age 17.2±0.3 years, body mass, 57.7±6.4 kg, and body height, 171.0±5.1 cm) groups before commencing the HIIT intervention. After completing five weeks of HIIT, both the HR-based and speed-based groups showed most likely moderate enhancement in high-intensity intermittent running performance (+9%, 90% confidence limits [CL] [6.4; 11.7]; standardized change [ES] +1.04 [0.75; 1.33]) and (+9.2%, [6.0; 12.5]; +1.09 [0.73; 1.46]), respectively. However, the difference between the experimental groups with regard to changes in high-intensity running performance was trivial. Between-group differences of weekly average HR and RPE responses showed trivial to moderate (ES range; -0.95; 0.15) and moderate to very large (ES: -0.63; -2.88) values, respectively. Although it seems that both the speed-based and HR-based HIIT approaches have some limitations when implementing for HIIT individualization, using the speed reached at the end of the 30-15 Intermittent Fitness test (VIFT) seems to elicit the same performance enhancement, but with lower psychophysiological responses during short-term interventions. [ABSTRACT FROM AUTHOR]

New training approaches have emerged advocating for the implementation of compensatory physical training. This approach aims to provide additional training that balances the load typically experienced by non-starters during a match. This may help maintain their readiness and ensures that their physical fitness is not compromised by the reduced exposure to match loads. Thus, this narrative review aims to describe the differences in external loads between starting and non-starting players and describe the studies conducted in compensatory training. Studies examining external load metrics such as total distances covered, high-speed running, and sprinting suggest that, adjusted for playing time, values are often higher in non-starting players. Although not standardized, there is an obvious decrease in exposure for these critical variables in non-starters. Additionally, internal load parameters such as perceived exertion and heart rate tend to be higher in starting players. Regarding the physical fitness impacts, evidence suggests differences observed between starters and non-starters in some aspects of physical performance, although the extent and significance of these differences can vary. The studies on compensatory training are limited, and the typical approach usually centres on running-based exercises and small-sided games, offering differing approaches to address the physical needs. The gap in research underscores the necessity for improved study designs that can shed light on the real impact of compensatory training. Presently, the practice of compensatory training has been adopted, yet a definitive understanding of its genuine influence, particularly in terms of enhancing physical fitness and mitigating injury risks, remains elusive., Competing Interests: The authors declare no conflict of interest., (Copyright © Institute of Sport – National Research Instutite.)

The COVID-19 lockdown challenged the training options of athletes worldwide, including players from the most popular sport globally, football/soccer., Purpose: The authors explored the training practices of football players worldwide during the COVID-19 lockdown., Methods: Football players (N = 2482, 30% professional, 22% semipro, and 48% amateur) completed an online survey (May-July 2020) on their training practices before versus during lockdown (March-June 2020). Questions were related to training frequency and session duration, as well as training knowledge and attitudes., Results: Before lockdown, more professional (87%) than semipro (67%) and amateur (65%) players trained ≥5 sessions/wk, but this proportion decreased during the lockdown to 55%, 35%, and 42%, respectively. Players (80%-87%) trained ≥60 minutes before lockdown, but this proportion decreased to 45% in professionals, 43% in amateurs, and 36% in semipros during lockdown. At home, more than two-thirds of players had training space (73%) and equipment (66%) for cardiorespiratory training, while availability of equipment for technical and strength training was <50% during lockdown. Interactions between coach/trainer and player were more frequent (ie, daily) among professional (27%) than amateur (11%) and semipro (17%) players. Training load monitoring, albeit limited, was mostly performed by fitness coaches, more so with professionals (35%) than amateurs (13%) and semipros (17%). The players' training knowledge and attitudes/beliefs toward training were relatively modest (50%-59%)., Conclusion: COVID-19 lockdown negatively affected training practices of football players worldwide, especially amateurs and semipros, for example, in training frequency, duration, intensity, technical, recovery, and other fitness training and coaching-related aspects. During lockdown-like situations, players should be monitored closely and provided appropriate support to facilitate their training.