Aerobic Energy Sources Research Articles

The physiological demands of elite epée fencers during competition

ABSTRACTThe aim of this study was to determine the physiological demands of epée fencing performance. Eight elite male epée fencers competed in a competition consisting of 7 Poule and 7 Direct Elimination (DE) fights. Core temperature (TC), heart rate (HR), movement patterns, training load, and differentiated ratings of perceived exertion (RPE) were collected for all Poule and DE fights. Expired gas, and energy expenditure (EE) were measured using breath-by-breath gas analysis during selected fights, along with blood lactate concentration. Maximal HR and RPE were greater in DE than Poule fights. There was a tendency for greater increases in TC in DE compared to Poule fights (p = 0.052). Blood lactate concentration decreased during the competition from Poule to DE suggesting reliance on phosphocreatine and aerobic energy sources during fencing. High oxygen consumption (~50 ml.kg−1.min−1) and EE (~13 kcal.min−1) were recorded in both Poule and DE. Fencers covered 3 times more distance in DE than Poule fights. High training load scores were also recorded. This is the first study to show an increased physiological strain, with high aerobic and anaerobic demands, as fencing competition progressed from Poule to DE. Additionally, there was a considerable energy demand exhibited during epée competition.

Ergometer Rowing With and Without Slides

A rowing ergometer can be placed on a slide to imitate 'on-water' rowing. The present study examines I) possible differences in biomechanical and physiological variables of ergometer rowing with and without slides and II) potential consequences on training load during exercise. 7 elite oars-women rowed in a randomized order in a slide or stationary ergometer at 3 predefined submaximal and at maximal intensity. Oxygen uptake was measured and biomechanical variables of the rowing were calculated based upon handle force (force transducer) and velocity/length (potentiometer) of the stroke. Stroke frequency was higher (%-difference between conditions) at each intensity level (1-11.4%, p<0.05) during slide compared to stationary rowing. Furthermore, at the 2 highest intensities a lower mean force (4.7-9.0%, p<0.05) and max force (3.2-10.6%, p<0.05) were observed on the slide ergometer. During maximal rowing no difference was seen in heart rate, mean oxygen uptake and R-value while maximal oxygen deficit was higher (30.8%, p<0.05) during slide rowing. In conclusion the biomechanical load is lower on a slide than on a stationary ergometer. However, as a training tool the slide ergometer seems just as demanding with regard to aerobic energy sources, and for anaerobic sources possibly even higher, compared with the stationary ergometer.

Physical Demands Of A Single Ballet Exercise In Adolescent Female Dancers

Classical ballet is one of the most ancient, performed and standardized system of dance. In spite of its long history and high diffusion, only limited studies give us information on the physiological aspects of ballet dance exercise. Purpose The purpose of this study was to compare the energy cost and the energy sources of the same ballet dance exercise performed by two different groups of dancers. Methods Two groups of adolescent female dancers ranging from 13–16 years of age performed a ballet dance exercise (210 seconds of “grand adage”). Subjects had different ballet practice: twelve advanced dancers (Group A: VO2max 46.2 ± 2.1 ml.kg−1·min−1) were training at least 10 h per week, while thirteen beginner dancers (Group B: VO2max 38.1 ± 1.9 ml.kg−1·min−1) were training on average of 4 h per week. Oxygen consumption (VO2) was measured by a telemetric system (K4 b2 COSMED system) before, during and after the dance exercise. The blood lactic acid concentration was measured at rest and at 3, 6, 10 minutes of the recovery phase. The overall energy requirement of dance exercise (VO2eq) was obtained by adding the amount of VO2 during exercise above resting (aerobic source: VO2ex) to the VO2 up to the fast component of recovery (anaerobic alactic source: VO2al) and to the energy equivalent of peak blood lactate accumulation (lactic source: VO2la) of recovery. Results Energy cost (VO2eq) of exercise performed by advanced dancers was 107 ± 4 ml.kg−1. The higher fraction of VO2eq was represented by VO2ex (65%). The remaining energy requirement (35%) was made up of VO2al (31%) and VO2la (4%). Energy cost (VO2eq) of exercise performed by beginner dancers was 106 ± 5 ml.kg−1. Fractions of aerobic, anaerobic alactic, and lactic energy sources were 50%, 41%, and 9% respectively. Between groups, significant differences (p<0.01) in VO2ex, VO2al and VO2la were found. Conclusions The overall energy cost of dance exercise performed by advanced and beginner dancers was similar. However, metabolic power requirement represented the 66% and 80% of VO2max for advanced and beginner dancers respectively. Moreover, the percent of energy source contribution was significantly different between groups. The utilization of aerobic energy source prevailed considerably in advanced dancers (group A). The aerobic energy source, was the most utilized also in group B, but the contribution of anaerobic alactic source was rather high. Only a limited contribution was offered by anaerobic lactic energy source in both groups.

Aerobic Energy Contribution during High Intensity Exercise

LANGUAGE NOTE | Document text in English; abstract also in Chinese.The review focuses on the aerobic energy contribution during high intensity cycling exercise. It is erroneous to assume that the energy demands of an exercise task can be met exclusively by either aerobic or anaerobic sources. During peak oxygen uptake determination, especially during the latter portions of the incremental exercise test, the anaerobic energy stores are also taxed. Not surprising, during maximal exercise of a short duration, there is also energy supplementation from aerobic energy sources. However, for a test to be considered predominantly anaerobic, the aerobic contribution to the test must be kept minimal. The quantification of aerobic contribution to a maximal exercise performance is difficult because the mechanical efficiency (ME) during a non-steady state exercise task remains speculative. Nevertheless extreme ME values for cycling have been proposed to provide a general scope of the estimated values. In adults, assumptions about oxygen uptake lag time, the size and role of the stored oxygen stores, which are taken into account also affect the magnitude to the aerobic contribution. Equivalent data on young people are insecure and greater research attention in this area is advised.本文著重介紹了大強度自行車運動中的有氧供能。如果認為運動中機體所需能量僅以某一能源系統，有氧系統或無氧系統供能是不正確的。在逐級遞增負荷測定最大攝氧量的運動中，尤其在測試的後階段，無氧系統參與供能。而在短時間的最大強度運動中，有氧供能也佔有一定的比例。即使進行無氧運動，在測試中仍能發現有低比例有氧供能。很難確定有氧系統在最大強度運動中的供能量為多少，因為不穩定狀態下的運動其供能效率仍不十分明確。但對於踏車運動中最高供能效率有一估計值範圍。對於成年人，攝氧量的延遲時間以及氧的儲存量的多少將影響最大有氧供能的比例。而在青少年中：有關這方面的資料較為缺乏，有待進一步的研究。

Effect of a warm-up on energy supply during high intensity exercise in horses.

The VO2(max) in racehorses is approximately double that of elite human athletes and the rate of increase in VO2 at the onset of high intensity exercise is much greater than in man. The kinetics of gas exchange are affected by a warm-up prior to exercise in humans, there being a greater aerobic contribution to high intensity exercise after warm-up. Our hypothesis was that a warm-up would increase aerobic energy delivery in racehorses during high intensity exercise. Thirteen fit Standardbred racehorses ran to fatigue at 115% of VO2(max) on a treadmill at 10% slope. Prior to acceleration, horses were exercised either for 5 min at 50% VO2(max) followed by 5 min walk, or walked for 2 min. Samples of expired gas were collected every 10 s during the run for determination of VO2 and VCO2 and measurement of maximal accumulated oxygen deficit (MAOD). Blood lactate concentration was measured 5 min post exercise. We found that with a warm-up, horses had faster kinetics of gas exchange and a greater proportion of their total energy requirement was supplied by aerobic sources. The aerobic contribution to total energy requirement with and without warm-up was, respectively, 79.3 +/- 1.0% and 72.4 +/- 1.7% (P < 0.01). There was also a higher MAOD (P < 0.01) in horses that had not been given a warm-up (mean +/- s.e.m. 34.7 +/- 2.6 and 47.3 +/- 2.6 mLO2eq/kg bwt with and without a warm-up respectively). However, there were no significant differences in total run time or estimated total energy expenditure between the 2 protocols. We concluded that during high intensity exercise to fatigue lasting 1 to 2 min, more than 70% of energy supply is from aerobic energy sources and that this contribution is even greater when the horses have received a warm-up.