Objectives Develop the Markov Index Load State (MILS) model, based on hidden Markov chains, to assess athletes’ workload responses and investigate the effects of menstrual cycle (MC)/oral contraception (OC), sex steroids hormones and wellness on elite athletes’ training.Methods On a 7-month longitudinal follow-up, daily training (volume and perceived effort, n=2200) and wellness (reported sleep quality and quantity, fitness, mood, menstrual symptoms, n=2509) data were collected from 24 female rowers and skiers preparing for the Olympics. 51 MC and 54 OC full cycles relying on 214 salivary hormone samples were analysed. MC/OC cycles were normalised, converted in % from 0% (first bleeding/pill withdrawal day) to 100% (end).Results MILS identified three chronic workload response states: ‘easy’, ‘moderate’ and ‘hard’. A cyclic training response linked to MC or OC (95% CI) was observed, primarily related to progesterone level (p=8.23e-03 and 5.72e-03 for the easy and hard state, respectively). MC athletes predominantly exhibited the ‘easy’ state during the cycle’s first half (8%–53%), transitioning to the ‘hard’ state post-estimated ovulation (63%–96%). OC users had an increased ‘hard’ state (4%–32%) during pill withdrawal, transitioning to ‘easy’ (50%–60%) when on the pill. Wellness metrics influenced the training load response: better sleep quality (p=5.20e-04), mood (p=8.94e-06) and fitness (p=6.29e-03) increased the likelihood of the ‘easy’ state. Menstrual symptoms increased the ‘hard’ state probability (p=5.92e-02).Conclusion The MILS model, leveraging hidden Markov chains, effectively analyses cumulative training load responses. The model identified cyclic training responses linked to MC/OC in elite female athletes.

Estimating the potential of alpine skiers is an unresolved question, especially because of the complexity of sports performance. We developed a potential estimation model based solely on the evolution of performance as a function of age. A bayesian mixed model allowed to estimate the potential curve and the age at peak performance for the population (24.81 ± 0.2) and for each individual as the uncertainty around this curve. With Gaussian mixtures, we identified among all the estimates four types of curves, clustered according to the performance level and the progression per age. Relying on the uncertainty calculated on the progression curve the model created also allow to estimate a score and an uncertainty associated with each cluster for all individuals. The results allows to: i) describe and explain the relationship between age and performance in alpine skiing from a species point of view (at 0.87%) and ii) to provide to sport staffs the estimation of the potential of each individual and her/his typology of progression to better detect sports potential. The entire methodology is based on age and performance data, but the progression identified may depend on parameters specific to alpine skiing.

This study aims to identify the potential bias of the relative age effect (RAE) in French alpine skiers and to propose a mathematical correction adjustment for such a bias. All performances and birthdates of skiers on the national and international circuit were collected from the 2004 up to 2019. A goodness-of-fit chi-square test and the residuals were used to study the distribution of birth trimesters in youth competitors. A linear relationship between the distribution of performances and the months obtains a calibration coefficient allowing to rebalance the performance by considering the effect of RAE. Individuals born at the beginning of the year are over-represented in the elite young selections in all disciplines for both genders. A coefficient based on the relationship between month of birth and performance adjusts individual performance and cancels out the effect of RAE. The results show that RAE is present in French alpine skiing. We present a method allowing to consider the effect of the RAE in the performances realized in each gender and discipline. This method allows coaches to have a more objective opinion on performance and to reduce selection bias.

Specific force capacities might be a limiting factor for alpine skiing performance, yet there is little consensus on the capabilities in question, and whether they differ between disciplines. We aimed to test discipline (speed and technical) and performance (event‐specific world standing) effects on lower limb force‐production qualities. National‐level skiers (N = 31) performed loaded squat jumps and isometric mid‐thigh pulls to detect dynamic force output at extremely low and high velocities and maximum isometric force and rate of force development, respectively. Discipline differences were assessed via a general linear model including performance and allowing for interaction effects, with performance associations further characterized via distinct Pearson's correlations. Jump height did not differentiate disciplines, with absolute power slightly higher in speed athletes (F(1,27) = 4.42, P = .045, ω2 = 0.10), and neither variables were related to performance. Speed athletes possessed greater dynamic force at low velocities (F0; F(1,27) = 13.8, P < .001, ω2 = 0.17), and greater relative and absolute maximum isometric force (F(1,25) = 11.19‐20.70, ω2 = 0.16‐0.22, P < .003). Overall, higher ranked athletes possessed more force‐dominant profiles (F(1,27) = 16.28, ω2 = 0.34; r = 0.60 to 0.67, P < .001) and increased rate of force development characteristics (average and maximum, r = −0.50 to −0.82, P < .048). Very robust associations existed between maximum isometric force and speed performance (r = −0.88, P < .001), but only a trend for higher absolute isometric force in technical athletes (r = −0.49, P = .052). Alpine skiers display a preponderance for dynamic force output at low velocities, and isometric force for speed athletes, which highlights the interest in specific assessment and conditioning practices for ski athletes.

In jumping, countermovement increases net propulsive force and improves performance. We aimed to test whether this countermovement effect is velocity specific and examine the degree to which this varies between athletes, sports or performance levels. Force-velocity profiles were compiled in high-level skiers (N= 23) and sprinters (N= 30), with their performance represented in their overall world ranking and season-best 100 m time, respectively. Different ratios between force-velocity variables were computed from squat and countermovement jumps (smaller = less effect): jump height (CRh), maximum power (CRP), force (CRF), and velocity (CRv). Countermovement effect differed per velocity (inverse relationship between CRF and CRv, rs = -0.74, p< .001), and variation force-velocity profiles with countermovement. Skiers exhibited smaller CRF (rrb = -0.675, p< .001), sprinters smaller CRv (rrb = 0.426, p= .008), and "moderate" velocity conditions did not differentiate groups (CRP or CRh, p> .05). 33% of the variance in skiers' performance level was explained by greater maximum force and a lower CRF (i.e., high explosiveness at low-velocities without countermovement), without an association for sprinters. Countermovement effect appears specific to movement velocity, sport and athlete level. Consequently, we advise sports-specific assessment, and potentially training to reduce the countermovement effect per the relevant velocity.

Alpine ski racers require diverse physical capabilities. While enhanced force production is considered key to high-level skiing, its relevance is convoluted. The aims of this study were to i) clarify the association between performance path length and velocity, ii) test the importance of radial force, and iii) explore the contribution of force magnitude and orientation to turn performance. Ski athletes ( N = 15) were equipped with ski-mounted force plates and a global navigation satellite system to compute the following variables over 14 turns: path length ( L ), velocity normalized energy dissipation [Δ e mech / v in ], radial force [ F r ], total force (both limbs [ F tot ], the outside limb, and the difference between limbs), and a ratio of force application ( RF = F r / F tot ). Data were course-averaged or separated into sectional turn groupings, averaged, and entered into stepped correlation and regression models. Our results support Δ e mech / v in as a discriminative performance factor ( R 2 = 0.50–0.74, p < .003), except in flat sections. Lower course times and better Δ e mech / v in were associated with greater F r ( R 2 = 0.34–0.69 and 0.31–0.52, respectively, p < .032), which was related to both F tot and RF ( β = 0.92–1.00 and 0.63–0.81, respectively, p < .001) which varied in predictive order throughout the sections. F tot was associated with increased outside limb force and a more balanced contribution of each limb ( β = 1.04–1.18 and -0.65– -0.92, respectively, p < .001). F r can be improved by either increasing total force output or by increasing technical effectiveness (i.e., proportionally more force radially) which should increase the trajectories available to the skier on the ski course.

Bottollier, V, Coulmy, N, Le Quellec, L, and Prioux, J. Energy demands in well-trained alpine ski racers during different duration of slalom and giant slalom runs. J Strength Cond Res 34(8): 2156-2164, 2020-The purpose of this study was to investigate the energy demands of different duration slalom (SL) and giant slalom (GS) events in well-trained alpine ski racers. Eight well-trained alpine ski racers (age: 18.2 ± 0.8 years; stature: 1.72 ± 0.10 m; body mass: 65.8 ± 12.0 kg) performed an incremental laboratory test on cycle ergometer and 4 standardized alpine ski runs: short (ST) and long (LG) versions of SL and GS (SLST, SLLG, GSST, and GSLG). Oxygen uptake (V[Combining Dot Above]O2) and heart rate (HR) were recorded continuously in all conditions. Blood lactate ([La]) was determined immediately before run and 3 and 5 minutes after run ([La]peak). The contribution of aerobic, glycolytic, and phosphagen energy systems was estimated. The aerobic system was the primary energy system involved in GSST (43.9 ± 5.7%) and GSLG (48.5 ± 2.5%). No significant difference in the contribution of aerobic and glycolytic systems was observed in SLST and SLLG. [La]peak was higher in SLLG (11.10 ± 2.41 mmol·L) than in GSST (8.01 ± 2.01 mmol·L). There was no difference in oxygen uptake peak between GSST and GSLG. Energetic training goals should focus on the improvement of both aerobic, glycolytic, and phosphagen systems for alpine ski racers who perform SL and GS. Giant slalom specialists might benefit from emphasizing the improvement of the aerobic system, without neglecting other systems.

EDITORIAL article Front. Physiol., 24 April 2019Sec. Exercise Physiology Volume 10 - 2019 | https://doi.org/10.3389/fphys.2019.00481

To analyze if live high–train low (LHTL) effectiveness is improved when daily training is guided by heart rate variability (HRV).

In elite endurance sport, the goal of training is to optimally distribute intensity and load to improve aerobic capacity [11, 35], and it is known that this distribution has to be individualised [11]. Some training periods are characterised by very high training load (TL) aimed at the maximal stress supportable by the athlete, followed by periods of lighter TL in order to induce supercompensation. The monitoring of fitness and fatigue is essential, but it remains difficult to diagnose training-induced fatigue. It is complex to differentiate the fatigue instrumental in enhanced physiological adaptations from the fatigue that overtakes the recovery capacities of the athlete and leads to nonfunctional overreaching (NFOR) or overtraining (OTS) [20]. Heart rate variability (HRV) has been presented as a promising tool to differentiate fatigue states, and many studies have reported the influence of the training components (intensity and volume) on HRV due to a modulation in autonomic nervous system (ANS) activity [2, 10, 14, 17, 20, 25, 46]. In a preceding study, we reported that HRV spectral analysis permits sorting four different patterns of fatigue in elite Nordic skiers [33], whereas a swimming Olympic champion displayed three different patterns [31]. Schmitt Laurent et al. Influence of Training Load ... Int J Sports Med 2018; 00: 00–00 Influence of Training Load and Altitude on HRV Fatigue Patterns in Elite Nordic Skiers

We aimed to analyse the relationship between training load/intensity and different heart rate variability (HRV) fatigue patterns in 57 elite Nordic-skiers. 1063 HRV tests were performed during 5 years. R-R intervals were recorded in resting supine (SU) and standing (ST) positions. Heart rate, low (LF), high (HF) frequency powers of HRV were determined. Training volume, training load (TL, a.u.) according to ventilatory threshold 1 (VT1) and VT2 were measured in zones I≤VT1; VT1VT2, IV for strength. TL was performed at 81.6±3.5% in zone I, 0.9±0.9% in zone II, 5.0±3.6% in zone III, 11.6±6.3% in zone IV. 172 HRV tests matched a fatigue state and four HRV fatigue patterns (F) were statistically characterized as F(HF-LF-)SU_ST for 121 tests, F(LF+SULF-ST) for 18 tests, F(HF-SUHF+ST) for 26 tests and F(HF+SU) for 7 tests. The occurrence of fatigue states increased substantially with the part of altitude training time (r2=0.52, p<0.001). This study evidenced that there is no causal relationship between training load/intensity and HRV fatigue patterns. Four fatigue-shifted HRV patterns were sorted. Altitude training periods appeared critical as they are likely to increase the overreaching risks.

Purpose: To analyze the effects of different training strategies (i.e., mainly intensity distribution) during living high – training low (LHTL) between elite cross-country skiers and Nordic-combined athletes. Methods: 12 cross-country skiers (XC) (7 men, 5 women), and 8 male Nordic combined (NC) of the French national teams were monitored during 15 days of LHTL. The distribution of training at low-intensity (LIT), below the first ventilatory threshold (VT1), was 80% and 55% in XC and NC respectively. Daily, they filled a questionnaire of fatigue, and performed a heart rate variability (HRV) test. Prior (Pre) and immediately after (Post), athletes performed a treadmill incremental running test for determination of V˙O2max and V˙O2 at the second ventilatory threshold (V˙O2V T2), a field roller-skiing test with blood lactate ([La-]) assessment. Results: The training volume was in XC and NC, respectively: at LIT: 45.9 ± 6.4 vs. 23.9 ± 2.8 h (p < 0.001), at moderate intensity: 1.9 ± 0.5 vs. 3.0 ± 0.4 h, (p < 0.001), at high intensity: 1.2 ± 0.9 vs. 1.4 ± 02 h (p = 0.05), in strength (and jump in NC): 7.1 ± 1.5 vs. 18.4 ± 2.7 h, (p < 0.001). Field roller-skiing performance was improved (-2.9 ± 1.6%, p < 0.001) in XC but decreased (4.1 ± 2.6%, p < 0.01) in NC. [La-] was unchanged (-4.1 ± 14.2%, p = 0.3) in XC but decreased (-27.0 ± 11.1%, p < 0.001) in NC. Changes in field roller-skiing performance and in [La-] were correlated (r = -0.77, p < 0.001). V˙O2max increased in both XC and NC (3.7 ± 4.2%, p = 0.01 vs. 3.7 ± 2.2%, p = 0.002) but V˙O2V T2 increased only in XC (7.3 ± 5.8%, p = 0.002). HRV analysis showed differences between XC and NC mainly in high spectral frequency in the supine position (HFSU). All NC skiers showed some signs of overreaching at Post. Conclusion: During LHTL, despite a higher training volume, XC improved specific performance and aerobic capacities, while NC did not. All NC skiers showed fatigue states. These findings suggest that a large amount of LIT with a moderate volume of strength and speed training is required during LHTL in endurance athletes.

The purpose of this study was to investigate the evolution of ground reaction force during alpine skiing turns. Specifically, this study investigated how turn phases and slope steepness affected the whole foot normal GRF pattern while performing giant slalom turns in a race-like setting. Moreover, the outside foot was divided into different plantar regions to see whether those parameters affected the plantar pressure distribution. Eleven skiers performed one giant slalom course at race intensity. Runs were recorded synchronously using a video camera in the frontal plane and pressure insoles under both feet's plantar surface. Turns were divided according to kinematic criteria into four consecutive phases: initiation, steering1, steering2 and completion; both steering phases being separated by the gate passage. Component of the averaged Ground Reaction Force normal to the ski's surface([Formula: see text], /BW), and Pressure Time Integral relative to the entire foot surface (relPTI, %) parameters were calculated for each turn phases based on plantar pressure data. Results indicated that [Formula: see text] under the total foot surface differed significantly depending on the slope (higher in steep sections vs. flat sections), and the turn phase (higher during steering2 vs. three other phases), although such modifications were observable only on the outside foot. Moreover, [Formula: see text] under the outside foot was significantly greater than under the inside foot.RelPTI under different foot regions of the outside foot revealed a global shift from forefoot loading during initiation phase, toward heel loading during steering2 phase, but this was dependent on the slope studied. These results suggest a differentiated role played by each foot in alpine skiing turns: the outside foot has an active role in the turning process, while the inside foot may only play a role in stability.

The purpose of this study was to measure the difference in normal force under both feet during alpine skiing giant slalom turns. Eleven experienced alpine skiers performed a giant slalom course at race intensity. All trials were recorded synchronously using a video camera and a plantar pressure measuring system. The mean force on the grouped two feet varied from 0.7 BW at the start of a turn to 1.5 BW during the steering phase of a turn performed in a steep slope condition. When skiing on FLAT slope condition, it reached only 1.3 BW. Results also showed that the outside foot receives significantly more pressure than the inside foot during the entire turn except the initiation phase. This last finding is not affected by slope steepness.

Background: There is little known about return to sport and performance after anterior cruciate ligament (ACL) tear in high-level alpine skiers. Purpose: To analyze the parameters that influence the return to sport and performance after an ACL tear in French alpine skiers from 1980 to 2013. Study Design: Descriptive epidemiology study. Methods: The study population included 239 male and 238 female skiers who competed on the national French alpine ski team for at least 1 season between 1980 and 2013 in the speed (downhill and super-G) and technical disciplines (giant slalom and slalom). Two groups were formed: group 1 (G1) included athletes who had sustained an ACL rupture, and group 2 (G2) included athletes who had never sustained an ACL rupture. Three performance indicators were selected: International Ski Federation (FIS) points calculation, FIS ranking, and podium finishes in the World Cup, World Championships, and Olympic Games. Results: The first-decile FIS points and international FIS ranking showed that G1 skiers obtained better performance than did G2 skiers. The mean ± SD career length of G1 skiers (men, 7.9 ± 4.7 years; women, 7.1 ± 4.1 years) was longer than that of G2 skiers (men, 4.5 ± 3.3 years; women, 4.2 ± 3.5 years). In addition, 12.8% (61 of 477) of the skiers achieved at least a podium finish during their careers: 23.0% (34 of 148) in G1 and 8.3% (27 of 329) in G2. The mean age at ACL rupture was 22.6 ± 4.1 years for men and 19.9 ± 3.5 years for women. In G1, 55 podiums were achieved before ACL rupture and 176 after in all competitions. Skiers who improved their performances after ACL rupture were significantly younger (men, 22.2 ± 3.0 years; women, 18.7 ± 2.2 years; P < .0001) at the time of injury than those showing a performance deterioration after ACL rupture (men, 25.3 ± 4.2 years; women, 22.4 ± 4.0 years). All skiers who had ACL tears continued their competitive careers after the injury. Conclusion: The overall results showed that it is possible to return to preinjury or even higher levels of performance after an ACL rupture and that age is the main element that guides postsurgical recovery.

This study investigated changes in heart rate variability (HRV) in elite Nordic-skiers to characterize different types of "fatigue" in 27 men and 30 women surveyed from 2004 to 2008. R-R intervals were recorded at rest during 8 min supine (SU) followed by 7 min standing (ST). HRV parameters analysed were powers of low (LF), high (HF) frequencies, (LF+HF) (ms(2)) and heart rate (HR, bpm). In the 1 063 HRV tests performed, 172 corresponded to a "fatigue" state and the first were considered for analysis. 4 types of "fatigue" (F) were identified: 1. F(HF(-)LF(-))SU_ST for 42 tests: decrease in LFSU (- 46%), HFSU (- 70%), LFST (- 43%), HFST (- 53%) and increase in HRSU (+ 15%), HRST (+ 14%). 2. F(LF(+) SULF(-) ST) for 8 tests: increase in LFSU (+ 190%) decrease in LFST (- 84%) and increase in HRST (+ 21%). 3. F(HF(-) SUHF(+) ST) for 6 tests: decrease in HFSU (- 72%) and increase in HFST (+ 501%). 4. F(HF(+) SU) for only 1 test with an increase in HFSU (+ 2161%) and decrease in HRSU (- 15%). Supine and standing HRV patterns were independently modified by "fatigue". 4 "fatigue"-shifted HRV patterns were statistically sorted according to differently paired changes in the 2 postures. This characterization might be useful for further understanding autonomic rearrangements in different "fatigue" conditions.

PurposeThis longitudinal study aimed at comparing heart rate variability (HRV) in elite athletes identified either in 'fatigue' or in 'no-fatigue' state in 'real life' conditions.Methods57 elite Nordic-skiers were surveyed over 4 years. R-R intervals were recorded supine (SU) and standing (ST). A fatigue state was quoted with a validated questionnaire. A multilevel linear regression model was used to analyze relationships between heart rate (HR) and HRV descriptors [total spectral power (TP), power in low (LF) and high frequency (HF) ranges expressed in ms(2) and normalized units (nu)] and the status without and with fatigue. The variables not distributed normally were transformed by taking their common logarithm (log10).Results172 trials were identified as in a 'fatigue' and 891 as in 'no-fatigue' state. All supine HR and HRV parameters (Beta±SE) were significantly different (P<0.0001) between 'fatigue' and 'no-fatigue': HRSU (+6.27±0.61 bpm), logTPSU (-0.36±0.04), logLFSU (-0.27±0.04), logHFSU (-0.46±0.05), logLF/HFSU (+0.19±0.03), HFSU(nu) (-9.55±1.33). Differences were also significant (P<0.0001) in standing: HRST (+8.83±0.89), logTPST (-0.28±0.03), logLFST (-0.29±0.03), logHFST (-0.32±0.04). Also, intra-individual variance of HRV parameters was larger (P<0.05) in the 'fatigue' state (logTPSU: 0.26 vs. 0.07, logLFSU: 0.28 vs. 0.11, logHFSU: 0.32 vs. 0.08, logTPST: 0.13 vs. 0.07, logLFST: 0.16 vs. 0.07, logHFST: 0.25 vs. 0.14).ConclusionHRV was significantly lower in 'fatigue' vs. 'no-fatigue' but accompanied with larger intra-individual variance of HRV parameters in 'fatigue'. The broader intra-individual variance of HRV parameters might encompass different changes from no-fatigue state, possibly reflecting different fatigue-induced alterations of HRV pattern.

Purpose. - To quantify the net energy expenditure and the respective implications of the aerobic and lactic energy sources over a giant slalom (GS) performed in the field in young ski racers.Methods. - Seven young alpine skiing competitors (14.0 +/- 0.5 years) volunteered to participate in the study. An inclusion session consisted of an evaluation of their peak oxygen consumption using a standardized incremental maximal aerobic test. Then, oxygen consumption was measured during an in situ GS. In addition, blood lactate concentrations were measured before and 2 minutes after the GS to determine the respective implications of the aerobic and lactic energy sources.Results. - At the end of the SG, lasting 76.4 +/- 10.9 seconds, oxygen consumption was 64.0 +/- 7.8% of the peak oxygen consumption and blood lactate concentration was 5.7 +/- 2.2 mmol/L. The total net energetic expenditure was 31.7 +/- 6.7 kJ/min Aerobic and lactic energy sources implications were 69.7 +/- 16.7% and 30.3 +/- 16.7%, respectively.Conclusion. - In comparison with previous values reported in adults, young ski racers show low levels of total energy expenditure while performing a GS. The ability to increase the total energy expenditure seems to be influenced by the lactic energy source involvement. (C) 2012 Published by Elsevier Masson SAS.