Effect of sauna-based heat acclimation on plasma volume and heart rate variability

Stanley, J., Halliday, A., D’Auria, S., Buchheit, M. and Leicht, AS. Effect of sauna-based heat acclimation on plasma volume and heart rate variability. Eur J App Physiol, In press.

PV EAJP Full text here / Video of the talk here

Abstract
Purpose: We investigated the effect of post-exercise sauna bathing on plasma volume (PV) expansion and whether such responses can be tracked by changes in heart rate (HR) based measures.
Methods: Seven, well-trained, male cyclists were monitored for 35 consecutive days (17 d baseline training, 10d training plus sauna, 8d training). Sauna exposure consisted of 30 min (87°C, 11% relative humidity) immediately following normal training. Capillary blood samples were collected to assess PV changes while resting seated. HR (HRwake) and vagal-related HR variability (natural logarithm of square-root mean squared differences of successive R−R intervals, ln rMSSDwake) were assessed daily upon waking. A sub-maximal cycle test (5 min at 125 W) was performed on days 1, 8, 15, 22, 25, 29, and 35 and HR recovery (HRR60s) and ln rMSSDpostex were assessed post-exercise. Effects were examined using magnitude-based inferences.
Results: Compared with baseline, sauna resulted in: 1) peak PV expansion after 4 exposures with a likely large increase [+17.8% (90% confidence limits, 7.4;29.2)]; 2) reduction of HRwake by a trivial-to-moderate amount [−10.2% (−15.9;−4.0)]; 3) trivial-to-small changes for ln rMSSDwake [4.3% (1.9;6.8)] and ln rMSSDpostex [−2.4% (−9.1;4.9)]; and 4) a likely moderate decrease in HRR60s [−15.6% (−30.9;3.0)]. Correlations between individual changes in PV and HR measures were all unclear.
Conclusions: Sauna-bathing following normal training largely expanded PV in well-trained cyclists after just 4 exposures. The utility of HR and HRV indices for tracking changes in PV was however uncertain. Future studies will clarify mechanisms and performance benefits of post-training sauna bathing.
Keywords: heat exposure; blood volume; cardiac parasympathetic activity; post-exercise; cyclists.

@jamiestanley85

Relative match intensities at high altitude in highly-trained young soccer players (isa3600)

qantas-joeys-held-to-scoreless-draw-in-bolivia_00048620-leadimageMartin Buchheit, Kristal Hammond, Pitre C. Bourdon, Ben M. Simpson, Laura A. Garvican-Lewis, Walter F. Schmidt, Christopher J. Gore and Robert J. Aughey. Relative match intensities at high altitude in highly-trained young soccer players (isa3600). Journal of Sports Science and Medicine, In press.

Figure 1Full text here

ABSTRACT

To compare relative match intensities of sea-level versus high-altitude native soccer players during a 2-week camp at 3600 m, data from 7 sea-level (Australian U17 National team, AUS) and 6 high-altitude (a Bolivian U18 team, BOL) native soccer players were analysed. Two matches were played at sea-level and three at 3600 m on Days 1, 6 and 13. The Yo-Yo Intermittent recovery test (vYo-YoIR1) was performed at sea-level, and on Days 3 and 10. Match activity profiles were measured via 10-Hz GPS. Distance covered >14.4 km.h-1 (D>14.4 km.h-1) and >80% of vYo-YoIR1 (D>80%vYo-YoIR1) were examined.

Upon arrival at altitude, there was a greater decrement in vYo-YoIR1 (Cohen’s d +1.0, 90%CL ± 0.8) and D>14.4 km.h-1 (+0.5 ± 0.8) in AUS. D>14.4 km.h-1 was similarly reduced relative to vYo-YoIR1 in both groups, so that D>80%vYo-YoIR1 remained similarly unchanged (-0.1 ± 0.8). Throughout the altitude sojourn, vYo-YoIR1 and D>14.4 km.h-1 increased in parallel in AUS, so that D>80%vYo-YoIR1 remained stable in AUS (+6.0%/match, 90%CL ± 6.7); conversely D>80%vYo-YoIR1 decreased largely in BOL (-12.2%/match ± 6.2).

In sea-level natives competing at high-altitude, changes in match running performance likely follow those in high-intensity running performance. Bolivian data confirm that increases in ‘fitness’ do not necessarily translate into greater match running performance, but rather in reduced relative exercise intensity.

Key words: association football; hypoxia; match running performance

Cardiac Parasympathetic Activity and Race Performance: An Elite Triathlete Case Study

Stanley J, D’Auria S, Buchheit M. Cardiac Parasympathetic Activity and Race Performance: An Elite Triathlete Case Study. Int J Sports Physiol Perform. 2014 Oct 29. [Epub ahead of print]

2s Men's caloundra enduro triathlon 2011 fs 2s-12-MAbstract

We examined whether changes in heart rate (HR) variability (HRV) could consistently track adaptation to training and race performance during a 32-week competitive season. An elite male long-course triathlete recorded resting HR (RHR) each morning and vagal-related indices of HRV (natural logarithm of square-root of mean squared differences of successive R-R intervals; ln rMSSD and the ratio of ln rMSSD to R-R interval length; ln rMSSD:RR) were assessed. Daily training load was quantified using a power meter and wrist-top GPS device. Trends in HRV indices and training load were examined by calculating standardised differences (ES). The following trends in week-to-week changes were consistently observed: 1) when the triathlete was coping to a training block, RHR decreased [ES, -0.38 (90% confidence limits, -0.05;-0.72)] and ln rMSSD increased [+0.36 (0.71;0.00)], 2) when the triathlete was not coping, RHR increased [+0.65 (1.29;0.00)] and ln rMSSD decreased [-0.60 (0.00;-1.20)], 3) optimal competition performance was associated with moderate decreases in ln rMSSD [-0.86 (-0.76;-0.95)] and ln rMSSD:RR [-0.90 (-0.60;-1.20)] in the week prior to competition, and 4) sub-optimal competition performance was associated with small decreases in ln rMSSD [-0.25 (-0.76;-0.95)] and trivial changes in ln rMSSD:RR [-0.04 (0.50;-0.57)] in the week prior to competition. To conclude, in this triathlete, a decrease in RHR concurrent with increased ln rMSSD compared with the previous week consistently appears indicative of positive training adaptation during a training block. A simultaneous reduction in ln rMSSD and ln rMSSD:RR during the final week preceding competition appears consistently indicative of optimal performance.

 

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

Effect of birth date on playing time during international handball competitions with respect to playing positions

Karcher, C, Ahmaidi S and Buchheit M. Effect of birth date on playing time during international handball competitions with respect to playing positions. Kinesiology 46(2014) 1:23-32. Full text here / Journal original website

Abstract: While a relative age effect (RAE) has been reported in handball, such analyses do not consider actual playing time during competitions, which may actually have more impact on performance in matches. The objective of the present study was to examine the RAE on playing time during international competitions with respect to playing positions. Team compositions (477 players) of the quarter finalists of the 2012 Olympic Games, 2013 World Championships, and 2014 European Championships were analyzed. Month and year of birth where collected in the starting list of each team for center, left and right backs, left and right wings, goalkeepers and pivots. Players were categorized into birth quartile (Q1 Jan–Mar; Q2 Apr–Jun; Q3 Jul– Sep; and Q4 Oct–Dec) and as odd/even year. Playing times were retrieved from official statistics. Data were analyzed for practical significance using magnitude-based inferences. We observed a strong selection bias towards players born earlier within a two-year selection period for all playing positions (Chi-square, p<.001). There was, however, an inconsistent effect of age (i.e. expected, reversed or a lack of it) on actual playing time during competitions. In conclusion, the present study showed for the first time that, despite its large effect on players’ selection, players’ relative age had a limited and position-dependent effect on their actual playing time during top-level competitions. Present findings suggest that the reasons supporting the relative age effect with respect to team selection are at odds with the current utilization of players by coaches in the field.

Key words: relative age effect, team selection, main competitions

 

Integrating different tracking systems in football

khalifa international stadium 2-2 Buchheit, M., Poon, T.K., Allen A., Modonutti, M.,  Gregson, W., and Di Salvo V. Integrating different tracking systems in football: multiple camera semi-automatic system, local position measurement and GPS technologies. J Sports Sci, 2014, In press. For 50 free reprints try here

Pages from Tracking system comparison Report 08.05.2013 - CopyAbstract
During the past decade substantial development of computer-aided tracking technology
has occurred. Therefore, we aimed to provide calibration equations to allow the
interchangeability of different tracking technologies used in soccer. Eighty-two highly-trained soccer players (U14-U17) were monitored during training and one game. Player
activity was collected simultaneously with a semi-automatic multiple-camera (Prozone),
local position measurement (LPM) technology (Inmotio) and two global positioning
systems (GPSports and VX). Data were analyzed with respect to three different field
dimensions (small, <30m2 to full-pitch, match). Variables provided by the systems were
compared, and calibration equations (linear regression models) between each system
were calculated for each field dimension. Most metrics differed between the four
systems with the magnitude of the differences dependant on both pitch size and the
variable of interest. Trivial-to-small between-system differences in total distance were
noted. However, high-intensity running distance (>14.4km/h) was slightly-to-moderately
greater when tracked with Prozone, and accelerations, small-to-very largely
greater with LPM. For most of the equations, the typical error of the estimate was of a
moderate magnitude. Interchangeability of the different tracking systems is possible
with the provided equations, but care is required given their moderate typical error of
the estimate.

Key Words: soccer; tracking system; match analysis; training load; agreement;
calibration equations.

Pages from Tracking system comparison Report 08.05.2013

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.

19e8f14d0fefc1da546be244d2de8960_400x400@ALDOLITO

Sensitivity of heart rate and psychometric measures to monitor physical performance in handball

Buchheit, M. Sensitivity of heart rate and psychometric measures to monitor physical performance in handball. Int J Sports Med, 2014, In press.

cropped-bandeauAbstract

 The aim of the present study was to examine whether monthly resting heart rate (HR), HR variability (HRV) and psychometric measures can be used to monitor changes in physical performance in highly-trained adolescent handball players. Data were collected in 37 adolescent players (training 10±2.1 h.wk-1) at 11 occasions from September to May during the in-season period, and included an estimation of training status (resting HR and HRV, the profile of mood state (POMS) questionnaire), and three physical performance tests (a 10-m sprint, a counter movement jump and a graded aerobic intermittent test, 30-15 Intermittent Fitness Test). The sensitivity of HR and psychometric measures to changes in physical performance was poor (<20%), irrespective of the training status markers and the performance measures. The specificity was however strong (>75%) irrespective of the markers and the performance measures. Finally, the difference in physical performance between players with better vs. worse estimated training status were all almost certainly trivial. The present results highlight the limitation of monthly measures of resting HR, HRV and perceived mood and fatigue to predict in-season changes in physical performance in highly-trained adolescent handball players. This suggests that more frequent monitoring might be required, and/or that other markers might need to be considered.

Key words: heart rate variability; POMS; speed tests; counter movement jump, 30-15 Intermittent Fitness Test; progressive statistics.