Assessing overreaching with HRR: what is the minimal exercise intensity required?

Le Meur Y, Buchhei M, Aubry A, Coutts AJ and Hausswirth Ch. Assessing overreaching with HRR: what is the minimal exercise intensity required? IJSPP 2016, In press.

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Figure 1 – Changes in heart rate recovery (HRR) at all running intensities during the maximal incremental running test during the overload period. f-OR: functional overreaching.

ABSTRACT

 Purpose: Faster heart rate recovery (HRR) following high-to-maximal exercise (i.e. ≥90% HRmax) has been reported in athletes suspected of functional overreaching (f-OR). This study investigated whether this response would also occur at lower exercise intensity. Methods and Results: Heart rate recovery and rate of perceived exertion (RPE) responses were compared during an incremental intermittent running protocol to exhaustion in twenty experienced male triathletes (8 control and 13 overload subjects led to f-OR) before (Pre), immediately after an overload training period (Mid) and following a 1-week taper (Post). Both groups demonstrated an increase in HRR values at Mid, but this change was very likely to almost certainly larger in the f-OR group at all running intensities (large to very large differences, e.g. +16 ±7 bpm vs. +3 ±5 bpm, in the f-OR and control groups at 11 km×h-1, respectively). The highest between-group differences in changes in HRR were reported at 11 km×h-1 (13 ±4 bpm) and 12 km×h-1 (10 ±6 bpm). A concomitant increase in RPE values at all intensities was reported only in the f-OR group (large-to-extremely large differences, +2.1 ±1.5 to +0.7 ±1.5 AU). Conclusion: These findings confirm that faster HRR does not systematically predict better physical performance. However, when interpreted in the context of the athletes’ fatigue state and training phase, HRR following submaximal exercise may be more discriminant than HRR measures taken following maximal exercise for monitoring f-OR. These findings may be applied in practice by regularly assessing HRR following submaximal exercise (i.e., during warm-up) for monitoring endurance athletes responses to training.

 Keywords: fatigue, overtraining, heart rate, cardiac response, endurance training

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Shooting performance and fly time in highly-trained wing handball players: not everything is as it seems

Karcher C & Buchheit M. Shooting performance and fly time in highly-trained wing handball players: not everything is as it seems. IJSPP 2016

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Abstract

Purpose: The aims of this investigation were to 1) assess the usefulness of counter movement jump (CMJ) testing to predict handball-specific jumping ability and 2) examine the acute effect of transiently- modified jumping ability (i.e., flight time) on shooting efficiency in wing players. Methods: Eleven young highly-trained wing players performed 3 counter movement jumps and 10 typical wing jump shots with 3 different modalities: without any constraint (CONTROL), while stepping on a 14-cm step (STEP) and wearing a weighted vest (VEST, 5% of body mass). Flight time and the associated scoring efficiency during the jump shots were recorded. Results:  There was no clear correlation between jump shot and CMJ flight time, irrespective of the condition (r=0.04-0.18). During jump shots, flight time was most likely longer (ES=1.42-1.97) with VEST (635.4±31 ms) and STEP (615.3±32.9 ms) than CONTROL (566±30.5 ms) and very likely longer with VEST than with STEP (ES=0.6). The correlation between scoring efficiency and jump shot flight time was not substantial both within each modality and for all shots pooled. The difference in scoring efficiency between the 3 jumps with the longest vs. shortest flight times were either small (VEST, 48% vs. 42%) or non-substantial (two other conditions). Conclusions: The use of CMJ as a predictor of handball-specific jumping ability is questioned given the dissociation between CMJ and jump shot flying time. These results also show that transiently-affected flight time may not affect scoring efficiency, which questions the importance of jumping ability for success in wing players.

 Key Words: shooting efficiency; strength training; transfer.

Metabolic power requirement of change of direction speed in young soccer players: not all is what it seems

Hader K, A Mendez-Villanueva , D Palazzi, S Ahmaidi and M Buchheit. Metabolic power requirement of change of direction speed in young soccer players: not all is what it seems. PlosOne, In press. Full text here

Abstract

Purpose. The aims of this study were to 1) compare the metabolic power demand of straight-line and change of direction (COD) sprints including 45° or 90°-turns, and 2) examine the relation between estimated metabolic demands and muscular activity throughout the 3 phases of COD-sprints.

Methods. Twelve highly-trained soccer players performed one 25-m and three 20-m sprints, either in straight-line or with one 45º- or 90º-COD. Sprints were monitored with 2 synchronized 100-Hz laser guns to assess players’ velocities before, during and after the COD. Acceleration and deceleration were derived from changes in speed over time (Figure 1). Metabolic power was estimated based on di Prampero’s approach (2005). Electromyography amplitude (RMS) of 2 lower limb muscles was measured. The expected energy expenditure during time-adjusted straight-line sprints (matching COD sprints time) was also calculated.

Results. As shown in Figure 2, locomotor-dependant metabolic demand was largely lower with COD (90°, 142.1±15.0 J.kg-1) compared with time-adjusted (effect size, ES = -3.0; 193.2±18.7 J.kg-1) and non-adjusted straight-line sprints (ES = -1.7; 168.4±18.2 J.kg-1). Metabolic power requirement was angle-dependent, moderately lower for 90º-COD vs. 45º-COD sprint (ES = -1.0; 149.5±12.9 J.kg-1). Conversely, the RMS was slightly– (45°, ES = +0.5; +2.1%, 90% confidence limits (±3.6) for vastus lateralis muscle (VL)) to-largely (90°, ES = +1.6; +6.1 (3.3%) for VL) greater for COD-sprints. Metabolic power/RMS ratio was 2 to 4 times lower during deceleration than acceleration phases (Figure 7).

Conclusion. Present results show that COD-sprints are largely less metabolically demanding than linear sprints. This may be related to the very low metabolic demand associated with the deceleration phase during COD-sprints that may not be compensated by the increased requirement of the reacceleration phase. These results also highlight the dissociation between metabolic and muscle activity demands during COD-sprints, which questions the use of metabolic power as a single measure of running load in soccer.

Key words: Energy demand, muscular activity, electromyography amplitude, acceleration, deceleration, sprint, braking forces, running load.

 

Fig 1w

Fig. 1: Electromyography amplitude (RMS) of vastus lateralis and biceps femoris muscles and speed profiles during sprints with (45° or 90°) or without (i.e., straight-line, SL) one change of direction (COD). 90°25: 25-m sprint with one 90°-COD. The medial panel represents the standardized difference (Std Diff) of RMS between COD- and SL- sprints. The number of ‘*’ and ‘†’ refers to possible, likely, very likely and almost certain difference versus straight-line and 45°-COD sprints, respectively.

 

Fig 2

Fig. 2: Estimated energy expenditure of sprints with (45° or 90°) or without (i.e., straight-line, SL) one change of direction (COD); 90°25: 25-m sprint with one 90°-COD. The upper panel represents the standardized difference (Std Diff) between COD- and SL sprints. Since 90°25 vs. 20-m SL sprints could not be properly compared (i.e., differences in both running time and distance), their standardized difference (black circle) was not provided. The number of ‘*’ and ‘†’ refers to possible, likely, very likely and almost certain between-sprints differences versus the 45°-COD sprint trial, and within-sprint differences vs. the acceleration phase, respectively. The associated number refers to the magnitude of the difference, with 1 standing for small, 2 for moderate, 3 for large and 4 for very large magnitude.

 

Fig7 Ratio phases

Fig. 7: Metabolic power/electromyography amplitude (RMS) ratio during the different phases of sprints with (45° or 90°) or without (i.e., straight-line (SL)) one change of direction (COD). 90°25: 25-m sprint with one 90°-COD; BF: biceps femoris; VL: vastus lateralis. The number of ‘*’ and ‘†’ refers to possible, likely, very likely and almost certain difference versus straight-line and 45°-COD sprints, respectively. The associated number refers to the magnitude of the difference, with 1 standing for small, 2 for moderate, 3 for large and 4 for very large magnitude

 

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

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

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HR vs Speed based HIT

Abstract

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.

Ali

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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

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Abstract

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.

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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 

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Abstract

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, W.kg-1) or locomotor demands (PGPS, W.kg-1). 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 W.kg-1 distances (all CVs >50%), while total distance, average PVO2 and PGPS showed CVs <10%. ICC ranged from very low- (acceleration and >20 W.kg-1 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 W.kg-1 questions its value for monitoring purposes in soccer.

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

Mechanical determinants of acceleration and maximal sprinting speed in highly-trained young soccer players

Buchheit, M., Samozino, P., Glynn, J., Simpson, B.M., Al Haddad, H., Mendez-Villanueva, A. and Morin, JB. Mechanical determinants of acceleration and maximal sprinting speed in highly-trained young soccer players. Journal of Sports Sci, In press.

Screenshot 2014-09-09 23.46.41

Abstract

 The aim of the present study was to examine, in highly-trained young soccer players, the mechanical horizontal determinants of acceleration (Acc) and maximal sprinting speed (MSS). Eighty-six players (14.1±2.4 yr) performed a 40-m sprint to assess Acc and MSS. Speed was measured with a 100-Hz radar and theoretical maximal velocity (V0), horizontal force (F0) and horizontal power (Pmax) were calculated. Within each age group, players were classified as High Acc/Fast MSS (>2% faster than group mean), medium (between -2 and +2%), and Low/Slow (>2% slower). Acc and MSS were very largely correlated (-0.79, 90%CL[-0.85;-0.71]). The determinants (multiple regression r2=0.84[0.78;0.89]) of Acc were V0 (partial r:0.80[0.72;0.86]) and F0 (0.57[0.44;0.68]); those of MSS (r2=0.96[0.94;0.97]) were V0 (0.96[0.94;0.97]) and Pmax (0.73[0.63;-0.80]). High/Med have likely greater F0 (cohen’s d: +0.8[0.0;1.5]), V0 (+0.6[-0.1;1.3]) and Pmax (+0.9[0.2;1.7]) than Low/Med. High/Fast have an almost certainly faster V0 (+2.1[1.5;2.7]) and a likely greater Pmax (+0.6[-0.1;1.3]) than High/Med, with no clear differences in F0 (-0.0[-0.7;0.6]). Speed may be a generic quality, but the mechanical horizontal determinants of Acc and MSS differ. While maximal speed training may improve both Acc and MSS, improving horizontal force production capability may be efficient to enhance sprinting performance over short distances.

 Keywords: football association; force-velocity profile; horizontally-oriented force

Changes in repeated-sprint performance in relation to change in locomotor profile in highly-trained young soccer players

How to use changes in non soccer-specific locomotor entities (i.e., maximal aerobic and sprinting speeds) to predict changes in performance that is believed to be soccer specific (although I have my doubts too!)

Figure 1Buchheit, M. and Mendez-Villanueva, A., Changes in repeated-sprint performance in relation to change in locomotor profile in highly-trained young soccer players, J Sports Sci., 2014, In press

To examine the effects of changes in maximal aerobic (MAS) and sprinting (MSS) speeds, and the anaerobic reserve (ASR), on repeated-sprint performance, 270 highly-trained soccer players (14.5±1.6 yr) completed three times per season (over 5 years) a maximal incremental running test to approach MAS, a 40-m sprint with 10-m splits to assess MSS and a repeated-sprint test (10×30-m sprints), where best (RSb) and mean (RSm) sprint times, and percentage of speed decrement (%Dec) were calculated. ASR was calculated as MSS-MAS. While ∆RSb were related to ∆MSS and ∆body mass (r2=0.42, 90%CL[0.34;0.49] for the overall multiple regression, n=334), ∆RSm was also correlated with ∆MAS and ∆sum of 7 skinfolds (r2 =0.43 [0.35;0.50], n=334). ∆%Dec was related to ∆MAS (r2=0.02 [-0.07;0.11], n=334). Substantial ∆MSS and ∆MAS had a predictive value of 70 and 55% for ∆RSm, respectively. Finally, ∆ASR per se was not predictive of ∆RSm (Cohen’s = +0.8 to -0.3 with increased ASR), but the greater magnitude of ∆RSm improvement was observed when MSS, MAS and ASR increased together (0.8 vs. +0.4 with ASR increased vs. not, additionally to MSS and MAS). Low-cost field tests aimed at assessing maximal sprinting and aerobic speeds can be used to monitor ∆RS performance.

Key words: football association; repeated-sprint ability; maximal sprinting speed; maximal aerobic speed; anaerobic speed reserve

Body Dimensions of Elite Handball Players

Karcher, C, Ahmaidi S and Buchheit M. Body Dimensions of Elite Handball Players With  Respect To Laterality, Playing Positions and Playing Standard. Journal of Athletic Enhancement SciTechnol, 2014, In press.

Abstract

Purpose: The aim of the present study was to examine, using a large player database, between-playing positions and playing standard differences in body dimensions.

Methods: We compared stature and body mass of 1295 male elite handball players from different playing positions, i.e., backs (left and right), center backs, goalkeepers, pivots, wings (left and right) and playing standards (European championship, Champions league matches and national leagues from Germany, Spain and France).

Results: When all playing standards were pooled together, wings (left 185±6cm, right 185±6cm) were almost certainly slightly-to-moderately shorter than center backs (188±5 cm), which were slightly-to-largely shorter than backs (left 196±5cm, right 194±5cm), pivots (194±6cm) and goalkeepers (193±5cm). Pivots (100.1±9.1kg) were almost certainly slightly-to-very-largely heavier than the other positions, with backs (left 95.1±7.6kg, right 92.5±8kg) and goalkeepers (93.5±8.5kg) being moderately-to-largely heavier than wings (left 83.3±7.8kg, right 82.1±7kg) and center backs (88±7.6kg). Center, left and right backs were almost certainly slightly-to-moderately taller in the European championships, goalkeepers and right wings in Champions league, left backs in the German first league and pivots in the Spanish first league. Center and left backs were almost certainly slightly-to-moderately heavier in the European championship. Left wings were almost certainly slightly heavier in the German first league and pivots in the Spanish first league.

Conclusions: These data show the importance of considering players’ laterality when assessing their body dimensions. They might also serve as anthropometric benchmarks when profiling talented young players.

Key words: stature; body mass; anthropometric benchmarks; talent identification; players selection.

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