La valutazione della risposta cardiometabolica durante l’attività di equitazione

Horse riding changes its meaning over time. Formerly horses were considered just for transports of humans and things. In last centuries they became hobbies and team mates for equestrian activities. Horse riding today includes several disciplines, and many of these are olimpic sports. As such, equestrian deserve the attention of sports researchers, who are interested in cardiometabolic adaptations during training and competition. Cardio-Pulmonary Exercise Test The cardio-pulmonary exercise testing (CPET) today is the most reliable test that provides data on cardio metabolic and ventilatory function during exercise. Data derive from the analisys of : VO2: oxygen uptake (ml/min); VCO2: carbon dioxyde production (ml/min); VE: pulmonary ventilation (L/min); HR: heart rate (bpm); It became fundamental to obtain and understanding of physiological capacities underlying sports performance. It would be useful to know the energy demands and whether the anaerobic metabolism is recruited. CO2 excess To obtain an index of anaerobic glicolysis, excess of carbon dioxyde production (CO2 excess) was assessed as follow: CO2 excess = VCO2- (RER rest ? VO2) WALK TROT CANTERING It is quite well correlated with the rate of lactate accumulation in the blood . (Hirakoba et al. 2006, Yano et al. 2002) It allows to continuous measuring of the recruitment of lactacid metabolism during exercise, without stopping. (Crisafulli et al. 2009) VO2, VCO2, VE e HR were recorded during a training session in which riders performed four gaits: walk, trot sitting, trot rising and canter. Data collected were subsequently compared to same parameters gathered during a previous incremental cardiopulmonary test on cycloergometer. However few studies described the cardiometabolic response during riding: Westerling’s study Westerling’s study VO2 varies according to different equine gaits, ranging between 40% and 80% of rider?s maximal aerobic power. The aerobic demands during riding test were high and corresponded to the oxygen uptake at a workload of 120 Watt in the bycicle ergometer test. Devienne and Guezennec's study Rider’s mean energy expenditure when riding was between 25 and 70% of VO2max. Different gaits require more energy expenditure by the rider because they need to work harder to maintain the centre of mass. Our study Ten riders were enrolled. They underwent two different tests: A) Cardiopulmonary exercise test (CPET): a standard incremental bicycle ergometer test until exhaustion on an electromagnetically braked cycle ergometer. VO2, VCO2, VE, and HR were measured by a gas analyzer (Ultima CPX, MedGraphics, USA). B) Riding session (RS): after 3 minutes of rest to collect baseline data, riders performed 5 minutes of walking, 10 minutes of trot, and 5 minutes of cantering. Throughout RS, VO2, VCO2, VE and HR were collected by a portable telemetric metabolimeter (VO2000, MedGraphics, USA). VO2 and VCO2 mean values gathered during RS were below the maximum and anaerobic threshold level reached during CPET. Futhermore all gaits required an energy expenditure significantly higher respect rest and the previous gait. MATERIALS AND METHODS parties Involved Nineteen athletes-riders between the ages of seventeen and forty years (mainly practitioners sporting-competitive), after giving informed consent, were involved in the testing and They are subjected to two different tests: one in the laboratory and the other on the field of horseback riding. EXPERIMENTAL PROTOCOL Cardiopulmonary exercise testing Exercise testing cardio-pulmonary (CPET) today it is the most reliable test to to provide data cardiometabolic and lung function during exercise. Data derived from the analysis: • VO2: oxygen consumption (ml / min); • VCO2: carbon dioxide production (ml / min); • VE: pulmonary ventilation (L / min); • HR: heart rate (bpm); This test has become essential for optimum sports performance and for the understanding of the physiological capabilities of the base. From the values of respiratory gases, measured during the CPET, you also get a useful capacity index anaerobic lactic-athlete. To obtain an index of use of anaerobic metabolism is measured the excess production of carbon dioxide (CO2 excess) via the following equation: Excess CO2 = VCO2- (RER rest • VO2), where RER stands for respiratory ratio calculated as the ratio VCO2 / CO2: ! 19! ! [CO2 = excess VCO2- (RER rest • VO2)] The graph of the figure below shows the trend of the excess CO2 in according to the different conditions of motion of the horse nell'equitazione (data laboratory). Previous experiments have shown that the excess CO2 correlates well with the rate of accumulation of lactate in the blood (10, 11). Moreover, this parameter allows continuous measurement of recruitment of lactate metabolism during exercise, without the need to stop in order to perform the blood samples necessary for this assessment (12). Instrumentation Metabolimeter Laboratory (CPX, Medgraphics, USA) to measure breath for breath: VO2, VCO2, Ve. Metabolimeter portable and wearable (VO2000, CPX, Medgraphics, USA) for the measurement of breath-by-breath: VO2, VCO2, Ve and frequency Heart rate (HR). Experimental session conducted in the laboratory Each athlete recruited performed a cardiopulmonary exercise testing to ergometer (CS), with incremental load until exhaustion (13). During the test they were detected values breath for breath: VO2, VCO2, VE, HR, through the use of metabolimeter CPX, Medgraphics, USA. Experimental session conducted on the field After a week of laboratory tests, each athlete recruited He performed a test drive of the horse (RS) with the following protocol: 1) Implementation of the control test consisting of 3 minutes of rest, for collecting basic data, 2) Perform a 5 minute walk, 3) Perform a 10-minute jog, 4) Make a 5-minute gallop. During the test RS were acquired the values of: VO2, VCO2, VE, HR, through metabolimeter wearable VO2000 - Medgraphics 2000 li He sent via radio to the stationary unit (14). Data processing For each trial phase, in the two sessions of tests performed, It was calculated the mean value ± the standard error (SE) of each variable considered in each subject tested. The average values were then compared with each other via the statistical test Analysis of variance (ANOVA) and differences were considered statistically significant for P <0.05. EXPERIMENTAL RESULTS In figure N ° 1 the vertical columns represent the average values ± ES of oxygen consumption (VO2 on the ordinate axis) during the various stages in which consisted of riding the test in the field, while the horizontal line dotted in red it represents the average value of maximum consumption oxygen (VO2-max) achieved by athletes during exercise testing incremental cycle ergometer, implemented in the laboratory. The horizontal line dotted in black it represents the value of the oxygen consumption corresponding to the anaerobic threshold (VO2-AT) during the experiment incremental.Conclusion Present findings demonstrate that each of the different gaits of equine movement requires different metabolic response It appears that, while walking and trotting involve predominantly the aerobic metabolism, anaerobic glycolisis is also recruited during cantering This fact probably reflects the diverse pattern of riders' muscle contraction during each of the specific equine movements