The tracking of morning fatigue status across in-season training weeks in elite soccer players

Thorpe RT, Strudwick AJ, Buchheit M, Atkinson G, Drust B and Gregson W. The tracking of morning fatigue status across in-season training weeks in elite soccer players. IJSPP, In Press. Full text here

Thorpe IJSPP 2016

Purpose: To quantify the mean daily changes in training and match load and any parallel changes in indicators of morning-measured fatigue across in-season training weeks in elite soccer players.
Methods/ Following each training session and match, ratings of perceived exertion (RPE) were recorded to calculate overall session load (RPE-TL) in 29 English Premier League players. Morning ratings of fatigue, sleep quality, muscle soreness, as well as sub-maximal exercise heart rate (HRex), post-exercise heart rate recovery (HRR%) and variability (HRV) were also recorded. Data were collected for a median duration of 3 weeks (range: 1-13) and reduced to a typical weekly cycle including a weekend match day. Data were analysed using within-subjects linear mixed models.
Results: RPE-TL was approximately 600 AU (95%CI: 546-600) higher on match day vs the following day (P<0.001). RPE-TL progressively decreased by ˜ 60 AU per day over the 3 days prior to a match (P<0.05).  Morning-measured fatigue, sleep quality and soreness tracked the changes in RPE-TL, being 35-40% worse on post-match day vs pre-match day (P<0.001).  Perceived fatigue, sleep quality and soreness improved by 17-26 % from post-match day 1 to day 3 with further smaller (7-14%) improvements occurring between post-match day 4 and pre-match day (P<0.01). There were no substantial or statistically significant changes in HRex, HRR% and HRV over the weekly cycle (P>0.05).
Conclusions: Morning-measured ratings of fatigue, sleep quality and muscle soreness but not HR-derived indices are sensitive to the daily fluctuations in session load experienced by elite soccer players within a standard in-season week.
Key Words-Training, Performance, Wellness, Recovery

Sprint running performance monitoring: methodological and practical considerations

Haugen T & Buchheit M. Sprint running performance monitoring: methodological and practical considerations. Sports Med 2015, In press

Full text here

Fig 4 R2

Fig. Percentage changes in 10-m sprint time and maximal sprinting speed (best 10-m split during a 40-m sprint, MSS) in a well-trained young soccer player. Error bars represent the typical error of each variable (i.e., 1.6 and 2.9% for 10-m and maximal sprinting speed (MSS), respectively, Table 2). Details of the methods have been published elsewhere [34]. The grey area represents trivial changes. *: likely change, **: very likely change and ***: almost certain change. Multiples of the smallest worthwhile changes (SWC) were used to assess the magnitude of the changes based on Cohen’s effect size principle, where 1, 3 and 6 multiples of the SWC stand for small, moderate and large changes.

The aim of this review is to investigate methodological concerns associated with sprint performance monitoring, more specifically the influence and magnitude of varying external conditions, technology and monitoring methodologies not directly related to human physiology. The combination of different starting procedures and triggering devices can cause up to very large time differences, which may be many times greater than performance changes caused by years of conditioning. Wind, altitude, temperature, barometric pressure and humidity can all combine to yield moderate time differences over short sprints. Sprint performance can also be affected by the athlete’s clothing, principally by its weight rather than its aerodynamic properties. On level surfaces, the track compliance must change dramatically before performance changes larger than typical variation can be detected. An optimal shoe bending stiffness can enhance performance by a small margin. Fully-automatic timing systems, dual-beamed photocells, laser guns and high-speed video are the most accurate tools for sprint performance monitoring. Manual timing and single-beamed photocells should be avoided over short sprint distances (10-20 m) due to large absolute errors. The validity of today’s GPS technology is satisfactory for long distances (>30 m) and maximal velocity in team sports, but multiple observations are still needed due to questionable reliability. Based on different approaches used to estimate the smallest worthwhile performance change and the typical error of sprint measures, we have provided an assessment of the usefulness of speed evaluation from 5 to 40 m. Finally, we provide statistical guidelines to accurately assess changes in individual performance; i.e., considering both the smallest worthwhile change in performance and the typical error of measurement, which can be reduced while repeating the number of trials.

Key points
-Monitored sprint times over very short distances may vary up to 50-60% due to differences in equipment and methodology
-Presented calibration equations are needed to compare sprint times across varying settings
-We provide guidelines to accurately monitor and interpret sprint performance changes, based on established magnitude thresholds and practices to decrease typical errors with trials repetitions

The effect of body mass on eccentric knee flexor strength assessed with an instrumented Nordic hamstring device (Nordbord) in football players

Figure 1Buchheit M, Cholley Y, Nagel M and Poulos N. The effect of body mass on eccentric knee flexor strength assessed with an instrumented Nordic hamstring device (Nordbord) in football players. Int J Sports Physiol and Perf, In press – full text hereFigure 2Abstract
Purpose. The aims of the present study were to 1) examine the effect of body mass (BM) on eccentric knee flexor strength using the Nordbord, and 2) offer simple guidelines to control for effect of BM on knee flexors strength.
Methods. Data from 81 soccer players (U17, U19, U21, senior 4th French division and professionals) and 41 Australian Football League (AFL) players were used for analysis. They all performed one set of three maximal repetitions of the bilateral Nordic hamstring exercise, with the greatest strength measure used for analysis. The main regression equation obtained from the overall sample was used to predict eccentric knee flexor strength from a given BM (moderate TEE, 22%). Individual deviations from the BM-predicted score were used as a BM-free index of eccentric knee flexor strength.
Results. There was a large (r = 0.55, 90% confidence limits: 0.42;0.64) correlation between eccentric knee flexor strength and BM. Heavier and older players (professionals, 4th French division and AFL) outperformed their lighter and younger (U17-U21) counterparts, with the soccer professionals presenting the highest absolute strength. Professional soccer players were the only ones to show strength values likely slightly greater than those expected for their BM.
Conclusions. Eccentric knee flexor strength, as assessed with the Nordbord, is largely BM-dependent. To control for this effect, practitioners may compare actual test performances with the expected strength for a given BM, using the following predictive equation: eccentric strength (N) = 4 x BM (kg) + 26.1. Professional soccer players with specific knee flexors training history and enhanced neuromuscular performance may show higher than expected values.

Keywords: hamstring strength; injuries; Australian Football League; soccer; association football.

Figure 3

The development of functional overreaching is associated with a faster heart rate recovery in endurance athletes

Aubry A, Hausswirth C, Louis J, Coutts AJ, Buchheit M & Le Meur Y. The development of functional overreaching is associated with a faster heart rate recovery in endurance athletes. Plos1, In press.

Purpose: The aim of the study was to investigate whether heart rate recovery (HRR)
may represent an effective marker of functional overreaching (f-OR) in endurance
athletes. Methods and Results: Thirty-one experienced male triathletes were tested (10
control and 21 overload subjects) before (Pre), and immediately after an overload
training period (Mid) and after a 2-week taper (Post). Physiological responses were
assessed during an incremental cycling protocol to exhaustion, including heart rate,
catecholamine release and blood lactate concentration. Ten participants from the
overload group developed signs of f-OR at Mid (i.e. -2.1 ± 0.8% decreased
performance with concomitant high perceived fatigue). Additionally, only the f-OR
group demonstrated a 99% chance to demonstrate an increase in HRR during the
overload period (+8 ± 5 bpm, large effect size). Concomitantly, this group also revealed
a >80% chance of decreasing blood lactate (-11 ± 14%, large), plasma norepinephrine
(-12 ± 37%, small) and plasma epinephrine peak concentrations (-51 ± 22%,
moderate). These blood measures returned to baseline levels at Post. HRR change
was negatively correlated to changes in performance, peak HR and peak blood
metabolites concentrations. Conclusion: These findings suggest that i) a faster HRR is
not systematically associated with improved physical performance, ii) changes in HRR
should be interpreted in the context of the specific training phase, the athletes
perceived level of fatigue and the performance response; and, iii) the faster HRR
associated with f-OR may be induced by a decreased central command and by a lower
chemoreflex activity.

Fig2CTL: controls; AF: acute fatigue; f-OR: functional overreaching.

 Anael   julien  Xtof

Aaron  Yann

Quantification of training and competition load across a season in an elite Australian Football Club

Ritchie D, Hopkins WG, Buchheit M, Cordy J, & Bartlett JD. Quantification of training and competition load across a season in an elite Australian Football Club. IJSPP, In press.

Figure 1Full text here


Purpose: Load monitoring in Australian Football (AF) has been widely adopted, yet team sport periodization strategies are relatively unknown. Here we have aimed to quantify training and competition load across a season in an elite AF team, using rating of perceived exertion (RPE) and GPS. tracking.

Methods: Weekly totals for RPE and GPS loads (including accelerometer data; Playerload) were obtained for 44 players across a full season for each training modality and for competition. General linear mixed models compared mean weekly load between 3x pre-season and 4x in-season blocks. Effects were assessed with inferences about magnitudes standardized with between-player SD.

Results: Total RPE load was most likely greater during pre-season, where the majority of load was obtained via skills and conditioning. There was a large reduction in RPE load in the last pre-season block. During in-season, half the total load came from games and the remaining half from training, predominantly skills and upper-body weights. Total distance, high-intensity running, and Playerload showed large to very large reductions from pre-season to in-season, whereas changes in mean speed were trivial across all blocks. All these effects were clear at the 99% level.

Conclusions: These data provide useful information about targeted periods of loading and unloading across different stages of a season. Our study also provides a framework for further investigation of training periodization in AF teams.

Key Words: Training organisation, training distribution, team sports

mG85mk-j_400x400  xOtMcx1U_400x400

@DeanRitchie26     @JonBartlett66

Heart rate-based versus speed-based high-intensity interval training in young soccer players

Rabbani and M. Buchheit. Heart rate-based versus speed-based high-intensity interval training in young soccer players. International Research in Science and Soccer II, 2015, In press

Full text here

HR vs Speed based HIT


While heart rate (HR) is often used to control exercise intensity during high-intensity interval training (HIT), this approach has several limitations, including the difficulty for practitioners to regulate running intensity. To overcome these limitations, using the speed reached at the end of the 30-15 Intermittent Fitness Test (VIFT) as the reference for running intensity has been suggested. The aim of the present study was to compare the effect of HR- vs. VIFT-based HIT on high-intensity intermittent running performance in young soccer players. Twenty two soccer players (15.12 ± 0.5 yrs) were divided in two different experimental groups including HR-based (n=10) or VIFT-based (n=12) HIT during their preseason preparation. The VIFT-based HIT group performed a 30-15 Intermittent Fitness Test before the intervention to detect player’s VIFT. All players performed a Yo-Yo Intermittent Recovery Test level 1 (YYIRT1) before and after the intervention. All players underwent the same conditioning and technical/tactical training programs for 4-5 weeks, except the method of individualizing soccer-specific HIT sessions with the ball (2 sessions of HIT=3 sets of 3:30 min): either according to 90-95% of maximal HR, or 65-70% VIFT. We then compared the between-group differences in weekly improvement in YYIRT1 using magnitude-based inferences. VIFT-based HIT produced likely greater weekly improvement in YYIRT1performance than HR-based HIT (+86%, 90%CL (1.5- 240%); standardized difference: +0.7(0.02- 1.40), chances for greater/similar/lower values of 95/4/1). Using VIFT as a reference speed for HIT programming may elicit greater high-intensity intermittent running performance improvements than using percentages of maximal HR in young soccer players.

Key words: high-intensity running programming; training individualization; high-intensity running performance; 30-15 Intermittent Fitness Test.



Assessing stride variables and vertical stiffness with GPS-embedded accelerometers: preliminary insights for the monitoring of neuromuscular fatigue on the field

Buchheit, M., Gray, A., and Morin J.B. Assessing stride variables and vertical stiffness with GPS-embedded accelerometers: preliminary insights for the monitoring of neuromuscular fatigue on the field. Journal of Sports Science & Medicine, In press, 2015


Full text


The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K), which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km/h) with or without his right ankle tapped (aimed at creating a stride imbalance), while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT) and flying (FT) time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations) data. The agreement between treadmill (criterion measure) and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K) and moderate (FT). The typical error of the estimate was trivial (CT), small (K) and moderate (FT), with nearly perfect (CT and K) and large (FT) correlations for treadmill vs. accelerometer. The tape induced very large increase in the right – left foot ∆ in CT, FT and K measured by the treadmill. The tape effect on CT and K ∆ measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ∆ FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running.

Keywords: movement tracking; fatigue monitoring; 

Monitoring locomotor load in soccer: is metabolic power, powerful?

Buchheit M, Manouvrier C, Cassirame J and Morin JB. Monitoring locomotor load in soccer: is metabolic power, powerful? Int J Sport Med, In press, 2015.

 Full text here 

MetabonotpowerulFigure 1. Oxygen uptake (VO2), speed and metabolic power estimated from locomotor demands (PGPS) during the warm-up and the 3 exercise bouts in a representative player. VO2max: maximal oxygen uptake reached during an incremental test to exhaustion.

Interview – discussion podcast on the paper here 



The aim of the present study was to examine the validity and reliability of metabolic power (P) estimated from locomotor demands during soccer-specific drills. Fourteen highly-trained young soccer players (15.4±1.6 yr) performed a soccer-specific circuit with the ball (3 x 1-min bouts, interspersed with 30-s passive recovery) on two different occasions. Locomotor activity was monitored with 4-Hz GPS units, while oxygen update (VO2) was collected with a portable gas analyzer. P was calculated using either net VO2 responses and traditional calorimetry principles (PVO2, or locomotor demands (PGPS, Distance covered into different speed, acceleration and P zones was recorded. Players covered 30 times more distance >20 W/kg (PGPS) than >14.4 km.h-1. While PGPS was 29 ± 10 % lower than PVO2 (Cohen’s d<-3) during the exercise bouts, it was 85 ± 7 % lower (d<-8) during recovery phases. The typical error of the estimate between PGPS vs PVO2 was moderate: 19.8%, 90% confidence limits: (18.4;21.6). The correlation between both estimates of P was small: 0.24 (0.14;0.33). Very large day-to-day variations were observed for acceleration, deceleration and >20 distances (all CVs >50%), while total distance, average PVO2 and PGPS showed CVs <10%. ICC ranged from very low- (acceleration and >20 distances) to-very high (PVO2). To conclude, PGPS largely underestimates the energy demands of soccer-specific drills, especially during the recovery phases. Together with its moderate agreement with calorimetry-related P estimations, the poor reliability of PGPS >20 questions its value for monitoring purposes in soccer.

Key words: soccer, acceleration, deceleration, energy demands, soccer-specific, training load.

Change of direction speed in soccer: How much braking is enough?

Hader K, Palazzi D and Buchheit M. Change of direction speed in soccer: How much braking is enough? Kinesiology 47(2015) 1:44-52

Full text here


Figure 1. Running speed during 20-m sprints with (45º and 90º) or without (straight line, SL) change of direction. The grey area represents the change of direction.



The aims of the present study were to examine 1) the validity and reliability of a new timing system to assess running kinematics during change of direction (COD), and 2) the determinants of COD-speed. Twelve young soccer players performed three 20-m sprints, either in straight line or with one 45º- or 90º-COD. Sprints were monitored using timing gates and two synchronized 100-Hz laser guns, to track players’ velocities before, during and after the COD. The validity analysis revealed trivial-to-small biases and smallto-moderate typical errors of the estimate with the lasers compared with the timing gates. The reliability was variable-dependent, with trivial- (distance at peak speed) to-large (distance at peak deceleration) typical errors. Kinematic variables were angle-dependent, with likely lower peak speed, almost-certainly slower minimum speed during the COD and almost-certainly greater deceleration reached for 90º-COD vs. 45º-COD sprints. The minimum speed during the COD was largely correlated with sprint performance for both sprint angles. Correlations with most of the other independent variables were unclear. The new timing system showed acceptable levels of validity and reliability to assess some of the selected running kinematics during COD sprints. The ability to maintain a high speed during the COD may be the determinant for COD-speed.

Key words: acceleration, deceleration, speed profile, sprint, laser gun, soccer

Psychometric and physiological responses to a pre-season competitive camp in the heat with a 6-hr time difference in elite soccer players

Buchheit, M., Cholley Y. and Lambert P. Psychometric and physiological responses to a pre-season competitive camp in the heat with a 6-hr time difference in elite soccer players. IJSPP, In press.

Purpose. The aim of the present study was to examine in elite soccer players some psychometric and physiological responses to a competitive camp in the heat, after travelling across 6 time-zones. Methods. Data from 12 elite professional players (24.6±5.3 yr) were analyzed. They participated in an 8-day pre-season summer training camp in Asia (heat index 34.9±2.4 ⁰C). Players’ activity was collected during all training sessions and the friendly game using 15-Hz GPS. Perceived training/playing load was estimated using session rate of perceived exertion (RPE) and training/match duration. Psychometric measures of wellness were collected upon awakening before, during and after the camp using simple questionnaires. HR response to a submaximal 4-min run (12 km/h) and the ratio between velocity and force load (accelerometer-derived measure, a marker of neuromuscular efficiency) response to 4 ~60-m runs (22-24 km/h) were collected before, at the end and after the camp. Results. After a large increase, the RPE/m.min-1 ratio decreased substantially throughout the camp. There were possible small increases in perceived fatigue and small decreases in subjective sleep quality on the 6th day. There were also likely moderate (~3%) decreases in HR response to the submaximal run, both at the end and after the camp, which were contemporary to possible small (~8%) and most-likely moderate (~19%) improvements in neuromuscular efficiency, respectively. Conclusions. Despite transient increases in fatigue and reduced subjective sleep quality by the end of the camp, these elite players showed clear signs of heat acclimatization, which were associated with improved cardiovascular fitness and neuromuscular running efficiency.

Fig 1 final color2

Figure 1. Upper panel: change in locomotor load (measured via GPS) and heat index before, during and after the Asian camp. The flights represent the different flying trips, with their specific duration indicated into brackets. As wearing GPS was not allowed during the official match, the total distance covered was extrapolated from historical club data (Team A) against Team B for illustration. The timing of the monitoring sessions is also indicated, with Run standing for the submaximal run and the 4 60-m runs, and Wellness for the psychometric questionnaires. Lower panel: changes in perceived training load (rate of perceived exertion, RPE, method) and the RPE/distance per min ratio. The gray area represents the Hong Kong (HK) camp, while the grey and shaded area represents the time spent in Beijing. ****: very likely different vs. pre camp.

Keywords: heart rate monitoring, wellness, neuromuscular efficiency, association football, heat training.