Michel Marina

Nutritional behavior of cyclists during a 24-hour team relay race: a field study report

BackgroundInformation about behavior of energy intake in ultra-endurance cyclists during a 24-hour team relay race is scarce. The nutritional strategy during such an event is an important factor which athletes should plan carefully before the race. The purpose of this study was to examine and compare the nutritional intake of ultra-endurance cyclists during a 24-hour team relay race with the current nutritional guidelines for endurance events. Additionally, we analyzed the relationship among the nutritional and performance variables.MethodsUsing a observational design, nutritional intake of eight males (mean ± SD: 36.7 ± 4.7 years; 71.6 ± 4.9 kg; 174.6 ± 7.3 cm; BMI 23.5 ± 0.5 kg/m2) participating in a 24-hour team relay cycling race was assessed. All food and fluid intake by athletes were weighed and recorded. Additionally, distance and speed performed by each rider were also recorded. Furthermore, before to the race, all subjects carried out an incremental exercise test to determine two heart rate-VO2 regression equations which were used to estimate the energy expenditure.ResultsThe mean ingestion of macronutrients during the event was 943 ± 245 g (13.1 ± 4.0 g/kg) of carbohydrates, 174 ± 146 g (2.4 ± 1.9 g/kg) of proteins and 107 ± 56 g (1.5 ± 0.7 g/kg) of lipids, respectively. This amount of nutrients reported an average nutrient intake of 22.8 ± 8.9 MJ which were significantly lower compared with energy expenditure 42.9 ± 6.8 MJ (P = 0.012). Average fluid consumption corresponded to 10497 ± 2654 mL. Mean caffeine ingestion was 142 ± 76 mg. Additionally, there was no relationship between the main nutritional variables (i.e. energy intake, carbohydrates, proteins, fluids and caffeine ingestion) and the main performance variables (i.e. distance and speed).ConclusionsA 24-hour hours cycling competition in a team relay format elicited high energy demands which were not compensated by energy intake of the athletes despite that dietary consumption of macronutrients did not differ to the nutritional guidelines for longer events.

High energy deficit in an ultraendurance athlete in a 24-hour ultracycling race.

This case study examined the nutritional behavior and energy balance in an official finisher of a 24-hour ultracycling race. The food and beverages consumed by the cyclist were continuously weighed and recorded to estimate intake of energy, macronutrients, sodium, and caffeine. In addition, during the race, heart rate was continuously monitored. Energy expenditure was assessed using a heart rate-oxygen uptake regression equation obtained previously from a laboratory test. The athlete (39 years, 175.6 cm, 84.2 kg, maximum oxygen uptake, 64 mL/kg/min) cycled during 22 h 22 min, in which he completed 557.3 km with 8760 m of altitude at an average speed of 25.1 km/h. The average heart rate was 131 beats/min. Carbohydrates were the main macronutrient intake (1102 g, 13.1 g/kg); however, intake was below current recommendations. The consumption of protein and fat was 86 g and 91 g, respectively. He ingested 20.7 L (862 mL/h) of fluids, with sport drinks the main fluid used for hydration. Sodium concentration in relation to total fluid intake was 34.0 mmol/L. Caffeine consumption over the race was 231 mg (2.7 mg/kg). During the race, he expended 15,533 kcal. Total energy intake was 5571 kcal, with 4058 (73%) and 1513 (27%) kcal derived from solids and fluids, respectively. The energy balance resulted in an energy deficit of 9915 kcal.

High bar swing performance in novice adults: effects of practice and talent.

An individuals a priori talent can affect movement performance during learning. Also, task requirements and motor-perceptual factors are critical to the learning process. This study describes changes in high bar swing performance after a 2-month practice period. Twenty-five novice participants were divided by a priori talent level (spontaneous-talented [ST] and nonspontaneous-talented [NST]) and compared to experienced gymnasts. Additionally, we assessed their perception of their performance level before and after practice. We defined three events independently for hip (H) and shoulder (S) angle joints and for the lag between consecutive events (phases [P]): the smallest angle during downswing (P1H, P1S), the largest angle after P1 (P2H, P2S), and the smaller angle during upswing (P3H, P3S). Movement performance variables were the maximum elevation on the downswing (Pi) and the upswing (Pf), and the total path between both (swing amplitude). Data were collected during pre-and postpractice sessions by two video cameras. At the end of both sessions, participants drew a sketch to represent their perception of their performance level relative to the Pi, Pf, and the hip events. Results showed a similar practice effect in the swing amplitude in both novice groups. However, the ST groups performance and perception variables on the downswing improved more than the NST group due to practice. This study suggests that (a) downswing improvements were easier than in the upswing, possibly due to familiarity of the visual reference in combination with proprioceptive feedback; and (b) being ST may involve a better or faster gain in perception of self-action compared to NST.

Coordination Analysis Reveals Differences in Motor Strategies for the High Bar Longswing among Novice Adults

Coordination between arm-trunk and trunk-leg is important for effective longswing performance. This research describes inter-segmental coordination changes after a practice period of longswing on high bar in a novice cohort. Novices were divided by initial skill level (talent) into two groups: spontaneously-talented, (ST, n = 10, closer to expert performance) and non-spontaneously-talented (NST, n = 15). Additionally, post-practice longswing coordination was compared to expert gymnasts (n = 9). Longswing amplitude and coordination (inter-joint reversal points and continuous relative phase, CRP) were assessed for pre- and post-practice sessions. ANOVAs showed similar practice effects in swing enlargements for the ST (11%) and NST (18%), but inter-joint reversal points and positive area in CRP during the downswing were different. Due to practice, the ST group paired shoulder and hip reversal points (events) during the downswing closer and with larger velocity of the arm in relation to the trunk than the NST group. The NST failed to modify coordination probably due to a large variability at the beginning of the downswing. Given a similar amount of practice, talent could help to achieve the right temporal events’ sequence during downswing, which would allow the exploration of different segmental coordination. However, upswing coordination of the novice groups (ST and NST) requires more focused practice to achieve expert levels than downswing, especially the arm-trunk coordination.

Physiological demands of cyclists during an ultra-endurance relay race: a field study report.

This study was to describe and compare the physiological demands of ultra-endurance cyclists during a 24 h cycling relay race. Eleven male athletes (means +/- SD: 34.8 +/- 5.6 years; 71.6 +/- 4.9 kg; 174.6 +/- 7.3 cm; BMI 23.5 +/- 0.5 kg/m2; VO2 max: 66.0 +/- 6.4 ml/kg/min) participated in the study; eight in teams with a format of four riders (4C) and three in teams with six riders (6C). To investigate exercise intensity, heart rate (HR) was recorded while cycling using portable telemetric monitors. Three different exercise intensities were defined according to the reference HR values obtained during a pre race laboratory incremental VO2 max test: Zone I (< anaerobic threshold [AT]), Zone II (between AT and the respiratory compensation point [RCP]), Zone III (> RCP). Total volume and intensity were integrated as a single variable (training impulse: TRIMP). The score for TRIMP in each zone was computed by multiplying the accumulated duration in this zone by a multiplier for this particular zone of exercise intensity. The average intensity did not differ between cyclists in 4C (means +/- SD; 4C: 87 +/- 3 HRmax) and 6C (87 +/- 1% of HRmax), despite the higher volume performed by 4C (means +/- SD; 4C: 361 +/- 65; 6C: 242 +/- 25 per min; P = 0.012). These differences in total exercise volume significantly affected the values TRIMP accumulated (means +/- SD; 4C: 801 +/- 98, confidence interval [CI] 95%: 719 - 884; 6C: 513 +/- 25, CI 95%: 451 - 575; P = 0.012). The ultra-endurance threshold of 4C and 6C athletes lies at about 87% of HRmax for both. Although the intensity profile was similar, the TRIMP values differed significantly as a consequence of the higher volume performed by the 4C cyclists.

Validez comparativa y fiabilidad de dos métodos para la valoración de la fuerza de salto vertical.

Resum La forga explosiva del tren inferior es pot valorar mitjancant la prova de salt vertical, mesurant: 1) l’abast de la ma durant el salt (Dma), o 2) el temps de vol mesurat en una plataforma de contactes, per avaluar l’elevacio del centre de gravetat (Dcg). Els objectius de l’estudi son establir la validesa comparativa entre els dos metodes de mesurament i la seva fiabilitat, aixi com relacionar matematicament els resultats de tots dos metodes a traves d’una equacio de regressio. Van ser estudiats 65 adults sans (35 homes i 30 dones; 46 ± 8 anys d’edat), els quals van fer tres intents de prova de salt vertical en que es van mesurar les dues variables de salt (Dma i Dcg) i es va seleccionar el millor intent (Dma max i Dcg max ). EI Dma max (40 ± 11 cm) va ser significativament superior que no el Dcg max (31 ± 8 cm). Aixi mateix, la fiabilitat de Dma (r=0,97; coeficiente de variacion=5%) va ser superior que la de Dcg (r=0,93; c.v.=6%). Es va determinar l’equacio: Dma max =1,06 Dcg max +0,11 pes -0,80 (n=59; rm=0,95; r 2 =0,90; SE=3,3 cm). Es pot concloure que: 1) tots dos metodes de mesurament de la prova de salt vertical son molt fiables, sobretot en valorar Dma segons la tecnica descrita; 2) la valoracio del Dma, comparada amb la del Dcg, resulta comparativament valida, mes fiable, mes senzilla i mes economica, rao per la qual concloem que la seva aplicabilitat en estudis de camp en adults es superior.

Plyometric training performance in elite-oriented prepubertal female gymnasts.

Abstract Marina, M and Jemni, M. Plyometric training performance in elite-oriented prepubertal female gymnasts. J Strength Cond Res 28(4): 1015–1025, 2014—We studied the effectiveness of a combined strength and plyometric training program (experimental period) on jumping performance when compared with a training routine on apparatus (control period) over 2 successive gymnastics training seasons. Nine female elite-orientated gymnasts (around 30-hour training per week) were participated in the study. The study was based on a 20-month longitudinal design covering 2 training seasons separated by a competitive period and transition periods. Each season included 1 control and 1 experimental period (Ctrl&Dgr;1 + Ex&Dgr;1 and Ctrl&Dgr;2 + Ex&Dgr;2, respectively). Before and after each control and experimental period, we assessed plyometric performance by means of drop jumps (DJs) from 20, 40, 60, 80, and 100 cm. The jump performance variables considered were flight time (FT), contact time (CT), flight-contact ratio (FC), and estimated mechanical power (also called Bosco expression [BE]), all of which were expressed as raw data and normalized (expressed as a percentage) with respect to the recordings at the beginning of each period of analysis. Flight time was the only variable to increase not only during both experimental periods but also during both controls. Our results confirmed larger relative increments of all the variables (FT, CT, BE, and FC), except for CT at DJs of 80 and 100 cm, during the experimental periods than during their respective previous control periods. Despite the additive effect of growth, development, and maturation, the gymnasts were not able to maintain the DJ performance accomplished during Ex&Dgr;1, thereby confirming detraining during the competitive and transition periods. We conclude that a combination of heavy resistance training with high impact plyometric jumps is effective in prepubertal gymnasts, despite their initial high level of physical conditioning.

Changes in Motor Strategies Across Age Performing a Longswing on the High Bar

Purpose: Improvements in motor performance and coordination may be impacted by the interaction of practice and organismic constraints. It has been proposed that these aspects of motor learning are achieved at a different time rate: first, during placement of the events (performance), and second, segmental spatiotemporal relationships (coordination). We focused on the acquisition of the longswing in high bar as one basic skill in gymnastics. The aim of this study was to determine how longswing performance and coordination change to increase swing amplitude as age and expertise increase. Method: One hundred and thirteen male gymnasts were classified into 5 distinct age groups (G1, G2, G3, G4, and G5) on the basis of the national competition rules. Longswing performance (swing amplitude and event placements) and coordination (positive and negative areas in the continuous relative phase) were measured for each group. Results: Analyses of variance revealed that the adequate placement and coordination of the earlier events were achieved in younger groups (G1, G2), while later events and their coordination were accomplished by the older groups (G3 through G5). Conclusion: Our results suggested that the process of longswing acquisition, as age and expertise increase, follows a progression parallel to the temporal occurrence of the task events, instead of the proposed learning sequence of event placement first and then coordination.

New indices for quantification of the power spectrum of heart rate variability time series without the need of any frequency band definition

This paper presents a new family of indices for the frequency domain analysis of heart rate variability time series that do not need any frequency band definition. After proper detrending of the time series, a cumulated power spectrum is obtained and frequencies that contain a certain percentage of the power below them are identified, so median frequency, bandwidth and a measure of the power spectrum asymmetry are proposed to complement or improve the classical spectral indices as the ratio of the powers of LF and HF bands (LF/HF). In normal conditions the median frequency provides similar information as the classical indices, while the bandwidth and asymmetry can be complementary measures of the physiological state of the tested subject. The proposed indices seem to be a good choice for tracking changes in the power spectrum in exercise stress, and they can guide in the determination of frequency band limits in other animal species.

Reliability and validity of a custom-made instrument including a hand-held dynamometer for measuring trunk muscle strength

BACKGROUND Measuring isometric strength is necessary in many areas of health and sport. However, trunk muscles have some particular characteristics that make them difficult to evaluate with simple, inexpensive instruments. OBJECTIVE To evaluate the reliability and validity of an instrument constructed with a hand-held dynamometer and a metallic structure (HHD+S) for measuring maximum isometric voluntary trunk muscle strength. METHODS Maximum isometric voluntary trunk muscle strength (extension, flexion and lateral flexion) was measured in 20 healthy individuals using the custom-made instrument (HHD+S) and the gold standard Back-Check (BC). RESULTS The results showed that the two instruments had high and similar intra-subject reliability. The validity of the HHD+S was demonstrated by the high Pearson coefficient correlation between the two instruments (r ⩾ 0.78). CONCLUSIONS Given the good trial reliability and the close correlation between the two instruments, we believe that the use of a hand-held dynamometer together with the custom-made metallic structure (HHD+S) allows an evaluation of the maximum isometric voluntary trunk muscle strength to be made, that is very similar in quality, accuracy and reliability to the BC.