Monitoring Within-Individual Dose-Response Relationships in Professional Soccer Players: The Importance of Fitness Level.

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.

Variability of External Load Measures During Soccer Match Play: Influence of Player Fitness or Pacing?

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.

Training Practices of Football Players During the Early COVID-19 Lockdown Worldwide.

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.

Monitoring training in women's volleyball: Supine or seated heart rate variability?

We aimed to examine changes in resting heart rate variability, submaximal exercising heart rate (HRex), countermovement-jump height (CMJ), perceptual wellbeing, and internal load throughout preparatory training in elite women's volleyball players. We also aimed to determine which HRV measurement position (supine vs. seated) provided greater associations with the various markers of training adaptation. Thirteen players (age = 25.8 ± 3.0 years, height = 178.1 ± 6.7 cm, weight = 69.7 ± 7.6 kg) were monitored throughout four successive training camps preceding the Asia Cup. Daily measures of the root-mean square of successive differences were used to calculate the mean (LnRMSSDM) and coefficient of variation (LnRMSSDCV) for each camp. Averages were also determined for Hooper's Index and session ratings of perceived exertion (sRPE). HRex and CMJ were tested at the start of each camp. RESULTS: Seated LnRMSSDCV, HRex, CMJ, and sRPE increased at camp 3 (p < 0.05), then reverted to values similar to camp 2. Changes in seated LnRMSSDM were associated with changes in HRex (r = -0.68 to -0.71, p < 0.05). Occasional associations (p < 0.05) were observed between LnRMSSDCV and Hooper's Index (r = 0.59) and CMJ (r = -0.57), and changes in HRex (r = 0.69) and HRR (r = -0.62). CONCLUSIONS: A reduced cardiorespiratory response to a standardized submaximal workload was associated with increased seated LnRMSSDM. Higher seated LnRMSSDCV was observed in response to increased sRPE and was often associated with decrements in various status markers. Seated LnRMSSD provided more associations with indicators of training adaptation than supine measures.

Session-to-session variations in external load measures during small-sided games in professional soccer players.

The aims of this study were 1) to analyse session-to-session variations in different external load measures and 2) to examine differences in within-session intervals across different small-sided game (SSG) formats in professional players. Twenty professional soccer players (mean ± SD; age 28.1 ± 4.6 years, height 176.7 ± 4.9 cm, body mass 72.0 ± 7.8 kg, and body fat 10.3 ± 3.8%) participated in 3v3, 4v4, and 6v6 SSGs under different conditions (i.e., touch limitations and presence of goalkeepers vs. free touch and ball possession drill) over three sessions. Selected external load measures-including total distance (TD), high-intensity running (HIR, distance covered > 14.4 km.h-1), high-speed running (HSR, distance covered > 19.8 km.h-1), and mechanical work (MW, accelerations and deceleration > 2.2 m.s2)-were recorded using GPS technology during all SSG sessions. Small to large standardized typical errors were observed in session-to-session variations of selected measures across SSGs. TD.min-1 showed less variability, having a coefficient of variation (CV) of 2.2 to 4.6%, while all other selected external load measures had CV values ranging from 7.2% to 29.4%. Trivial differences were observed between intervals in TD.min-1 and HIR.min-1 for all SSGs, as well as in HSR.min-1 and MW.min-1 for most SSG formats. No reductions or incremental trends in session-to-session variations were observed when employing touch limitations or adding goalkeepers. The increased noise observed in higher speed zones (e.g., high-speed running) suggests a need for more controlled, running-based conditional drills if the aim is greater consistency in these measures.

Dose-Response Relationships between Training Load Measures and Physical Fitness in Professional Soccer Players.

The aim of this cohort study was two-fold: (i) to analyze within-group changes of final velocity in a 30-15 intermittent fitness test (VIFT), final velocity in a Vameval test (Vvameval), 20-m sprint and countermovement jump (CMJ); (ii) to explore the relationships between VIFT and Vvameval outcomes and their changes with internal and external loads. Twenty-two professional soccer players (mean ± SD; age 27.2 ± 3.4 years, height 174.2 ± 3.6 cm, body mass 69.1 ± 6.4 kg, and body fat 10.4 ± 4.1%, 3.1 ± 1.5 years in the club) participated in this study. External and internal loads were obtained using global positioning system, heart rate and rate of perceived effort (sRPE) after each training session. Players were assessed in CMJ, 20-m sprint, Vameval and 30-15 intermittent fitness test, before and after the observed period. Very large relationships were observed between VIFT and Vameval for pre- (r = 0.76), post (r = 0.80) and pooled-data (r = 0.81). Vvameval showed less sensitivity (-22.4%, [-45.0 to 9.4]), ES -0.45 [-1.05 to 0.16]) than VIFT. ∆VIFT had unclear associations with all sRPE, but had moderate correlations with objective internal and external measures, while, ∆Vvameval varied between large and very large relationships with all sRPE, but had unclear associations with all other selected training loads. Objective internal and external loads may be used to track aerobic power related changes from VIFT.

Relationships Between Aerobic Performance, Hemoglobin Levels, and Training Load During Small-Sided Games: A Study in Professional Soccer Players.

The purposes of this study were (1) to analyze between-session variations of external and internal load measures during small-sided games (SSGs) and (2) to test the relationships between the maximum speed reached (VIFT) during the last stage of the 30-15 Intermittent Fitness Test, hemoglobin levels, and training load measures during SSG intervals among professional soccer players. Sixteen professional soccer players (mean ± SD; age 27.2 ± 3.4 years, height 174.2 ± 3.6 cm, body mass 69.1 ± 6.4 kg, and body fat 10.4 ± 4.1%) participated in this study. Hemoglobin and aerobic performance were first tested, and then a 3-week SSG program was applied using a 3 vs. 3 format. During those 3 weeks, internal and external load of entire sessions were also monitored for all training sessions. Trivial-to-small, standardized differences were observed between sessions for external and internal measures during SSGs. Total distance (TD) and mechanical work (MW) were the only variables that indicated small changes. Large-to-very-large relationships were found between VIFT and external loads: TD (r range: 0.69; 0.87), high-intensity running (HIR; r range: 0.66; 0.75), and MW (r range: 0.56; 0.68). Moderate-to-large negative relationships were found between hemoglobin levels and internal loads: Edwards' TRIMP (r range: -0.36; -0.63), %HRmax (r range: -0.50; -0.61), and red zone (r range: -0.50; -0.61). VIFT had unclear relationships with overall internal loads, while hemoglobin levels presented unclear relationships with overall external loads. In conclusion, no meaningful changes were found between sessions considering the format of play used. Additionally, the detected relationships indicate that VIFT and hemoglobin levels are good indicators of the performance capacity and physiological profile of players during SSGs. Also, the use of SSGs protocols as a monitoring complement of the 30-15IFT is suggested.

Session-to-session variations of internal load during different small-sided games: a study in professional soccer players.

The aim of this study was to analyse variations of internal load across small-sided games (SSG) in professional soccer. Twenty players (mean ± SD; age 28.1 ± 4.6 yo, height 176.7 ± 4.9 cm, weight 72.0 ± 7.8 kg) performed 3v3, 4v4, and 6v6 formats with/without goalkeeper and touch limitations. Each condition was repeated over three sessions and heart rate (HR) measures including average HR (HRavg), Edwards' training impulse (Edwards' TRIMP) and time in red zone (>80% of maximal HR) were recorded. All measures had trivial-to-moderate typical error (TE) and trivial differences were observed within intervals. The HRavg showed less coefficient of variations (0.9% to 1.7%) compared to Edwards'TRIMP.min-1 and red zone.min-1 (2% to 9.7%). A reduction trend in TE was observed when touching limitations or using goalkeepers. Practitioners can use different SSG formats but if the aim is to have less noise at higher intensities, more controlled drills are recommended.

Fitness Monitoring in Elite Soccer Players: Group vs. Individual Analyses.

Rabbani, A, Kargarfard, M, and Twist, C. Fitness monitoring in elite soccer players; group vs. individual analyses. J Strength Cond Res 34(11): 3250-3257, 2020-The aims of this study were to (a) examine changes in group and individual HR measures during a submaximal warm-up test, and (b) investigate the relationship between accumulated internal training loads and HR changes during an in-season phase among elite soccer players (n = 14). Before and after an in-season phase (24 days), exercise HR (HRex) and HR recovery (HRR) expressed either as the number of beats recovered (HRR60s) or as the mean HR (HRpost1) during 1 minute of recovery were analyzed. Heart rate measures were expressed as the % of maximal HR. Session rating of perceived exertion (sRPE) was computed for all training/match sessions. Group and individual HR changes were analyzed using magnitude-based inferences. Pearson correlation coefficients were also used to examine the relationships. Group analyses of HR changes revealed there were possibly to likely trivial changes in all HR measures. When analyzing individual data, no substantial change was observed for HRR60s%. However, substantial changes in HRex% and HRpost1% were observed for 4/14 and 5/14 players, respectively. The relationships between HRex% and HRpost1% were nearly perfect (r = 0.90, confidence limits [0.82-0.95]). The associations between changes in HRex% and HRpost1% were also nearly perfect (r = 0.92, 0.80-0.97). A very large inverse correlation was observed between HRex% and accumulated sRPE (r = -0.75, -0.44 to -0.90). This study highlights the value of conducting individual vs. group aerobic fitness monitoring. This study also showed the importance of how HRR is reported when aerobic fitness monitoring of elite soccer players.

Combined Small-Sided Game and High-Intensity Interval Training in Soccer Players: The Effect of Exercise Order.

The aim of the present study was to compare combined small-sided game (SSG) and high-intensity interval training (HIT) with different order. Twenty-one semi-professional soccer players were divided into two groups: SSG+HIT (n = 10) and HIT+SSG (n = 11), and underwent similar four-week training programs. Players completed the 30-15 Intermittent Fitness Test (30-15IFT) before and after the experiment; maximum speed (VIFT) was recorded. During the experiment, seven sessions of SSG (3 vs 3) and HIT (15"-15" with 95-100% VIFT) were implemented. Weekly accumulated training loads for both groups during the experiment were similar. Moderate improvements in VIFT were observed in both SSG+HIT (+6.2%, 90% confidence limits, [CL] 4.6; 7.7 and Effect Size, [ES] +0.96) and HIT+SSG (+6.9%, 90% CL 4.6; 9.3 and ES +0.97) groups. Between-group difference in changes of VIFT was trivial (+0.7%, 90% CL -1.8; 3.3 and ES +0.11). Combining SSG and HIT in different order elicited the same enhancement in high-intensity intermittent performance in soccer players.

Session-To-Session Variations of External Load Measures of Youth Soccer Players in Medium-Sided Games.

The aim of this study was to analyze the variability of time-motion variables during five vs. five games when completed within the same session as, and between, two different sessions. Ten under-19 male soccer players (18.27 ± 0.47 years old) participated in this study. The five vs. five matches (3 × 5 min) were played twice with a 3-day interval of rest in the same week. Moderate between-session variations were observed for TD (total distance) (range coefficient of variation (CV), 6.9; 8.3%, confidence interval (CI), (5.0; 14.0), standardized typical error (STE), 0.68; 1.06, (0.64; 1.75)) and RD (running distance) (range CV, 53.3; 145.7%, (36.6; 338.9), STE, 0.83; 1.09, (0.60; 1.76)). PL (player load) showed small variations (range CV, 4.9; 6.0%, [3.6; 10.1], STE, 0.37; 0.43, (0.27; 0.71)). In within-session analyses for examining the differences between sets, a small decrease was observed in RD in set 3 versus set 2 (-14.8%, 90% CI (-32.1; 6.9%); standardized difference (ES): -0.39 (0.95; 0.16)). TD decreased with moderate (-3.5%, (-6.8; -0.1%); ES: -0.65(-1.30; -0.01)) and large (-8.2%, (-11.4; -4.9%); ES: -1.58(-2.24; -0.92)) effects in sets 2 and 3, respectively, versus set 1. Our results suggest that PL is the most stable performance variable. It was also verified that measures had a progressive decreasing tendency within a session.

Ratings of perceived recovery and exertion in elite youth soccer players: Interchangeability of 10-point and 100-point scales.

The purpose of this study was to examine the interchangeability of a new perceived recovery status scale (PRS) of 100 points through a comparison to the original 10-point version. This study also aimed to test the interchangeability of CR100 scale (Borg's rate of perceived exertion scale) in comparison to the CR10. Twenty-five male elite youth soccer players (age: 18.0 ±â€¯0.5 years old; body mass: 70.1 ±â€¯6.7 kg; height: 177.8 ±â€¯6.5 cm; experience: 11.7 ±â€¯1.2 years) from the same team competing in the first national under-19 competition participated in this study. During two consecutive weeks, the players completed PRS (both 10- and 100-points) and CR10 and CR100 scales. Nearly perfect relationships were observed between 0-to-10 and 0-to-100 scales, both for recovery status (r = 0.96, confidence interval [0.95;0.97]) and ratings of perceived exertion (RPE) (r = 0.97 [0.97;0.98]). Moreover, almost 95% of individuals showed nearly-perfect-to-perfect associations between 0-to-10 and 0-to100 in terms of RPE and recovery scales. Both a PRS of 100 points and CR100 can be used interchangeably with a PRS of 10 points and CR10, respectively.

Training/Match External Load Ratios in Professional Soccer Players: A Full-Season Study.

The aim of this study was two-fold: (i) to describe the training/match ratios of different external load measures during a full professional soccer season while analyzing the variations between different types of weeks (three, four and five training sessions/week) and (ii) to investigate the relationship between weekly accumulated training loads and the match demands of the same week. Twenty-seven professional soccer players (24.9 ± 3.5 years old) were monitored daily using a 10-Hz global positioning system with a 100-Hz accelerometer. Total distance (TD), running distance (RD), high-speed running (HSR), sprinting distance (SD), player load (PL), number of high accelerations (ACC), and number of high decelerations (DEC) were recorded during training sessions and matches. An individual training/match ratio (TMr) was calculated for each external load measure. Weeks with five training sessions (5dW) presented meaningfully greater TMr than weeks with four (4dW) or three (3dW) training sessions. Additionally, TDratio (TDr) was significantly greater in 5dW than in 3dW (mean differences dif: 1.23 arbitray units A.U.) and 4dW (dif: 0.80 A.U.); HSRr was significantly greater in 5dW than in 3dW (dif: 0.90 A.U.) and 4dW (dif: 0.68 A.U.); and SDr was significantly greater in 5dW than in 3dW (dif: 0.77 A.U.) and 4dW (dif: 0.90 A.U.). Correlations between the weekly training loads and the match demands of the same week were small for PL (r = 0.250 [0.13;0.36]), ACC (r = 0.292 [0.17;0.40]) and DEC (r = 0.236 [0.11;0.35]). This study reveals that ratios of above 1 were observed for specific measures (e.g., HSR, SD). It was also observed that training sessions are not adjusted according to weekly variations in match demands.

Match Fatigue Time-Course Assessment Over Four Days: Usefulness of the Hooper Index and Heart Rate Variability in Professional Soccer Players.

The aims of the present study were to (a) examine recovery time-course and (b) analyze the usefulness of the Hooper-Index (wellness index) and resting heart rate variability (HRV) in professional soccer players during an in-season phase. The Hooper-Index and resting HRV were collected on matchday and on the four following days in three consecutive in-season weeks in nine players (25.2 ± 4.3-years). The usefulness of monitoring variables was assessed by (a) comparing noise (typical error, TE) to the smallest worthwhile change (SWC) (TE/SWC) and (b) comparing match-related changes (i.e., signal) to TE (i.e., signal-to-noise ratio). Between-days standardized differences in the changes of Hooper-Index and HRV were compared to the SWC using magnitude-based inferences. The magnitudes of TE were small and moderate for the Hooper-Index and HRV, respectively. The Hooper-Index showed to be more useful than HRV for monitoring match-induced fatigue as having a lower TE/SWC (3.1 versus 4.4) and a higher signal-to-noise ratio (5.5 versus 1.5). Small-to-very large [range of effect sizes, 0.48; 2.43, confidence limits (0.22; 2.91)] and moderate-to-large [-1.71; -0.61 (-2.44; -0.03)] detrimental changes in Hooper-Index and HRV, respectively, were observed on the days following matchday. While group analyses showed a similar pattern for recovery time-course, more individual players responded, similarly when tracked using the Hooper -Index compared to when they were tracked using HRV. An inverse moderate within-individual relationship was observed between changes in the Hooper index and HRV [r = -0.41, (-0.60, 0.18)]. The Hooper index is an easy-to-use, no-cost, and non-invasive monitoring tool and seems promising for tracking match-induced fatigue during in the season in professional soccer.

Associations Between Selected Training-Stress Measures and Fitness Changes in Male Soccer Players.

PURPOSE: To investigate the relationship between accumulated global positioning system-accelerometer-based and heart rate-based 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 intermittent-running capacity of professional soccer players.

Variations of external load variables between medium- and large-sided soccer games in professional players.

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 (24.63[Formula: see text]2.84 years old; 180.94[Formula: see text]6.49 cm; 77.19[Formula: see text]6.46 kg; 52.99[Formula: see text]5.01 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.

Monitoring collegiate soccer players during a congested match schedule: Heart rate variability versus subjective wellness measures.

The aims of this study were a) to examine within-group changes of wellness and heart rate variability measures and b) to compare their sensitivity to a congested match schedule in collegiate soccer players (n = 8). Wellness (Hooper index and its subsets) and heart rate variability (Ln rMSSD, SDNN) measures were assessed after selected low-load (training sessions) and high-load (a congested match schedule) phases. Session rating of perceived exertion (sRPE) was computed for training and match sessions. A very likely large difference in accumulated sRPE was observed between low-load and high-load phases (+148.4%, 90% confidence interval CI [87.3; 229.5%]); effect size, ES, 2.16 [1.49; 2.82]. While the Hooper index showed an almost certainly moderate increase (+49.8%, [33.9; 67.5%]), ES, 1.05 [0.76; 1.34], heart rate variability measures (i.e., Ln rMSSD and SDNN) only changed with a possible trivial effect (range -2.1; 8.2%, [-7.1; 16.7%]), ES, -0.15; 0.15 [-0.50; 0.44]. The Hooper index showed a moderately higher sensitivity than Ln rMSSD to a congested match schedule (34.7%, [26.9; 41.6%], ES, 0.81 [0.60; 1.03]). Relationships between changes in the Hooper index and some of its subsets (∆Hooper index, ∆sleep, and ∆fatigue), with changes in mean sRPE (∆sRPE) were very large (range r = 0.72; 0.89). However, small associations were observed between changes in heart rate variability (∆Ln rMSSD, and ∆SDNN) and ∆sRPE (range r = -0.21; 0.10). This study suggests the use of subjective wellness indices, instead of heart rate variability measures, to monitor collegiate soccer players during congested match schedules.

Reliability and Validity of a Submaximal Warm-up Test for Monitoring Training Status in Professional Soccer Players.

Rabbani, A, Kargarfard, M, and Twist, C. Reliability and validity of a submaximal warm-up test for monitoring training status in professional soccer players. J Strength Cond Res 32(2): 326-333, 2018-Two studies were conducted to assess the reliability and validity of a submaximal warm-up test (SWT) in professional soccer players. For the reliability study, 12 male players performed an SWT over 3 trials, with 1 week between trials. For the validity study, 14 players of the same team performed an SWT and a 30-15 intermittent fitness test (30-15IFT) 7 days apart. Week-to-week reliability in selected heart rate (HR) responses (exercise heart rate [HRex], heart rate recovery [HRR] expressed as the number of beats recovered within 1 minute [HRR60s], and HRR expressed as the mean HR during 1 minute [HRpost1]) was determined using the intraclass correlation coefficient (ICC) and typical error of measurement expressed as coefficient of variation (CV). The relationships between HR measures derived from the SWT and the maximal speed reached at the 30-15IFT (VIFT) were used to assess validity. The range for ICC and CV values was 0.83-0.95 and 1.4-7.0% in all HR measures, respectively, with the HRex as the most reliable HR measure of the SWT. Inverse large (r = -0.50 and 90% confidence limits [CLs] [-0.78 to -0.06]) and very large (r = -0.76 and CL, -0.90 to -0.45) relationships were observed between HRex and HRpost1 with VIFT in relative (expressed as the % of maximal HR) measures, respectively. The SWT is a reliable and valid submaximal test to monitor high-intensity intermittent running fitness in professional soccer players. In addition, the test's short duration (5 minutes) and simplicity mean that it can be used regularly to assess training status in high-level soccer players.

Predicting changes in high-intensity intermittent running performance with acute responses to short jump rope workouts in children.

The aims of the present study were to 1) examine whether individual HR and RPE responses to a jump rope workout could be used to predict changes in high-intensity intermittent running performance in young athletes, and 2) examine the effect of using different methods to determine a smallest worthwhile change (SWC) on the interpretation of group-average and individual changes in the variables. Before and after an 8-week high-intensity training program, 13 children athletes (10.6 ± 0.9 yr) performed a high-intensity running test (30-15 Intermittent Fitness Test, VIFT) and three jump rope workouts, where HR and RPE were collected. The SWC was defined as either 1/5(th) of the between-subjects standard deviation or the variable typical error (CV). After training, the large ~9% improvement in VIFT was very likely, irrespective of the SWC. Standardized changes were greater for RPE (very likely-to-almost certain, ~30-60% changes, ~4-16 times >SWC) than for HR (likely-to-very likely, ~2-6% changes, ~1-6 times >SWC) responses. Using the CV as the SWC lead to the smallest and greatest changes for HR and RPE, respectively. The predictive value for individual performance changes tended to be better for HR (74-92%) than RPE (69%), and greater when using the CV as the SWC. The predictive value for no-performance change was low for both measures (<26%). Substantial decreases in HR and RPE responses to short jump rope workouts can predict substantial improvements in high-intensity running performance at the individual level. Using the CV of test measures as the SWC might be the better option. Key pointsDecreased HR and RPE responses to short jump rope workouts can be confidently used to track improvements in high-intensity intermittent running performance in children familiarized with this exercise mode. Rope jumping is a particularly convenient exercise, since it can be performed in a restricted space and allows the testing of a large number of athletes simultaneously.We recommend using the CV of the measures (i.e., 3 and 4% for HR and RPE (OMNI scale) responses, respectively) as the SWC.

The 30-15 Intermittent Fitness Test versus the Yo-Yo Intermittent Recovery Test Level 1: relationship and sensitivity to training.

The aim of the current study was to examine the relationship between performance of the Yo-Yo Intermittent Recovery Test Level 1 (Yo-YoIR1) and the 30-15 Intermittent Fitness Test (30-15IFT) and to compare the sensitivity of both tests to training. Fourteen young soccer players performed both tests before and after an 8-wk training intervention, which included 6 sessions/wk: 2 resistance training sessions, 2 high-intensity interval training sessions after technical training (4 sets of 3:30 min of generic running and small-sided games [4v4] during the first and second 4-wk periods, respectively [90-95% maximal HR], interspersed with 3 min at 60-70% maximal HR), and 2 tactical-only training sessions. There was a large correlation between 30-15IFT and Yo-YoIR1 (r = .75, 90% confidence limits [CL] 0.57;0.86). While within-test percentage changes suggested a greater sensitivity to training for the Yo-YoIR1 (+35%, 90%CL 24;45) than for the 30-15IFT (+7%; 4;10), these changes were similarly rated as almost certain (with chances for greater/similar/lower values after training of 100/0/0 for both tests) and moderate, ie, standardized difference, ES = +1.2 90%CL (0.9;1.5) for Yo-YoIR1 and ES = +1.1 (0.7;1.5) for 30-15IFT. The difference in the change between the 2 tests was clearly trivial (0/100/0, ES = -0.1, 90%CL -0.1;-0.1). Both tests might evaluate slightly different physical capacities, but their sensitivity to training is almost certainly similar. These results also highlight the importance of using standardized differences instead of percentage changes in performance to assess the actual training effect of an intervention.