Predicting maximal lactate steady state from lactate thresholds determined using methods based on an incremental exercise test in beagle dogs: A study using univariate and multivariate approaches.

The reliability of four lactate threshold (LT) methods to estimate the maximal lactate steady state (MLSS), defined as the highest intensity that can be maintained without plasma lactate ([La-]) accumulation over time, was determined in Beagle dogs. Six male Beagle dogs performed a standardized incremental exercise test on a treadmill when plasma lactate ([La-]) measurements were performed. The LTs for predicting MLSS, were determined by visual inspection (LTV), using a bi-segmented linear regression model (LTBI), or using a polynomial function on the [La-]/velocity ratio (LTP) by considering the vertices of the curve and calculating the point that yields the maximal distance from a curve representing [La-] as a function of velocity to the line formed by the two endpoints of the curve (LTDMAX method). The agreement was assessed using Bland-Altman plots and ordinary least products (OLP) regression among the velocities corresponding to the LTs identified using different methods (VLTv, VLTBI, VLTP, and VLTDMAX) and the velocity corresponding to the MLSS (VMLSS). A principal component (PC) analysis approach was performed to detect the degree of co-relatedness among the variables. The mean ± SD [La-] at MLSS was 1.03 ± 0.24 mM. VMLSS had a lower mean bias with VLTv, followed by VLTBI. The VLTDMAX underestimated MLSS. VLTv and VLTBI had the lowest limits of agreement with the VMLSS. The VLTP and VLTDMAX showed relatively high limits of agreement with MLSS. VLTv, VLTBI, and VMLSS had more collinearity and were dominantly aligned with the second component (PC2). VLTv and VLTBI can be used as simple methods to objectively determine aerobic fitness in Beagle dogs.

Workload of official contests, net cost of transport, and metabolic power of Mangalarga Marchador horses of marcha batida or picada gaits.

This study aimed to characterize the maximum heart rate (HR) and the intensity of official marcha contests (OMC) and to compare the cost of transport (COT) and metabolic power (Pmet) of Mangalarga Marchador (MM) horses of marcha batida (MB) and marcha picada (MP) gaits. Twenty-two MM horses participated in this study. The experiment was conducted in 3 phases: 1) maximum effort test (MET), 2) OMC, and 3) standardized marcha test (SMT). To characterize the HR, 19 horses (14 MB and 5 MP) underwent a MET. Of those, 13 (9 MB and 4 MP) were monitored during the OMC, which consisted of 4 stages: marcha, walk, functional trial, and rest. The average heart rate (HR) in each stage of the OMC was related to the HR to determine their relative intensity. The SMT was performed with 14 horses (9 MB and 5 MP), of which 11 had already participated in the previous stages. The COT and Pmet were calculated from the HR values obtained during the SMT. Blood samples were collected to analyze plasma lactate concentration ([Lac]). One-way ANOVA or 1-way repeated-measures ANOVA followed by the Tukey's test ( < 0.05) were used to analyze the results. The average HR was 211 ± 11 and 214 ± 11 beats/min (bpm) for the MB and MP groups, respectively, with no difference ( = 0.7066) between them. The [Lac] increased as a result of the MET ( < 0.05), with no difference between groups ( > 0.05). This indicated that horses of both groups had the same physical fitness levels. The OMC stages defined in our study differed ( < 0.05) regarding the relative intensity of the HR, except for the walk and standing stages, which were similar ( = 0.0875). The MP group presented greater COT ( = 0.0247) and Pmet ( = 0.0193). It can be concluded that the mean HR of MM horses (MB and MP) is 212 ± 11 bpm. The OMC of the MM breed can be characterized as an effort of intermittent and submaximal intensity. In addition, the locomotion of the MB horses is probably more energetically efficient than that of MP horses.

Comparison of maximal lactate steady state with V2, V4, individual anaerobic threshold and lactate minimum speed in horses / Comparação da máxima fase estável do lactato com a V2, V4, o limiar anaeróbio individual e lactato mínimo em equinos

The anaerobic threshold is a physiologic event studied in various species. There are various methods for its assessment, recognized in the human and equine exercise physiology literature, several of these involving the relationship between blood lactate concentration (LAC) and exercise load, measured in a standardized exercise test. The aim of this study was to compare four of these methods: V2, V4, individual anaerobic threshold (IAT) and lactate minimum speed (LMS) with the method recognized as the gold standard for the assessment of anaerobic threshold, maximal lactate steady-state (MLSS). The five tests were carried out in thirteen trained Arabian horses, in which velocities and associated LAC could be measured. The mean velocities and the LAC associated with the anaerobic threshold for the five methods were respectively: V2 = 9.67±0.54; V4 = 10.98±0.47; V IAT = 9.81±0.72; V LMS = 7.50±0.57 and V MLSS = 6.14±0.45m.s-1 and LAC IAT = 2.17±0.93; LAC LMS = 1.17±0.62 and LAC MLSS = 0.84±0.21mmol.L-1. None of the velocities were statistically equivalent to V MLSS (P<0.05). V2, V4 and V LMS showed a good correlation with V MLSS , respectively: r = 0.74; r = 0.78 and r = 0.83, and V IAT did not significantly correlate with V MLSS. Concordance between the protocols was relatively poor, i.e., 3.28±1.00, 4.84±0.30 and 1.43±0.32m.s-1 in terms of bias and 95% agreement limits for V2, V4 and LMS methods when compared to MLSS. Only LAC LMS did not differ statistically from LAC MLSS. Various authors have reported the possibility of the assessment of anaerobic threshold using rapid protocols such as V4 and LMS for humans and horses. This study corroborates the use of these tests, but reveals that adjustments in the protocols are necessary to obtain a better concordance between the tests and the MLSS.

O limiar anaeróbio é um evento fisiológico estudado em várias espécies. Sua mensuração possui vários métodos reconhecidos na literatura da fisiologia do exercício humano e equino, muitos deles envolvendo a relação entre a concentração sanguínea de lactato (LAC) e a carga de exercício. O objetivo do presente estudo foi comparar quatro desses métodos: V2 , V4 , limiar anaeróbio individual (LAI) e o teste do lactato mínino (LM) com o método reconhecido na literatura como o padrão ouro para a mensuração do limiar anaeróbio, a máxima fase estável do lactato (MFEL). Os cinco testes foram realizados em treze equinos árabes treinados, nos quais as velocidades e suas respectivas LAC puderam ser quantificadas. As velocidades médias e LAC associadas ao limiar anaeróbio aferido pelos cinco métodos foram respectivamente: V2 = 9,67±0,54; V4 = 10,98±0,47; V LAI = 9.81±0.72; V LM = 7,50±0,57 e V MFEL = 6,14±0,45m.s-1 ; e LAC LAI = 2,17±0,93; LAC LM = 1,17±0,62 e LAC MFEL = 0,84±0,21mmol.L-1. Nenhuma dessas velocidades foi estatisticamente igual à V MFEL (P<0,05). A V2 , a V4 e a V LM mostraram uma boa correlação com a V MFEL , respectivamente r = 0,74; r = 0,78 e r = 0,83, e a V LAI não se correlacionou significativamente com a V MFEL. A concordância entre os protocolos foi relativamente fraca, sendo 3,28±1,00; 4,84±0,30 e 1,43±0,32m.s-1 em termos de viés e limites de concordância a 95% para os métodos V2 , V4 e LM comparados à MFEL. Muitos autores relataram a possibilidade da mensuração do limiar anaeróbio pelo uso de protocolos rápidos, como a V4 e o LM, para humanos e equinos. O presente estudo corrobora a utilização desses testes, mas revela que ajustes nos protocolos são necessários para se obter uma melhor concordância entre os mesmos e a MFEL.

Comparison of the lactate minimum speed and the maximal lactate steady state to determine aerobic capacity in purebred Arabian horses.

AIM: To compare five different protocols for estimating the lactate minimum speed (LMS) with that for estimating the maximal lactate steady state (MLSS) in Arabian horses, in order to obtain a more rapid method for monitoring aerobic capacity and prescribing training schedules. METHODS: Eight purebred Arabian horses were conditioned to exercise on a treadmill for 12 days then submitted to three to five exercise sessions to determine the MLSS. Blood samples were collected from a jugular catheter at specific intervals for measurement of lactate concentrations. The MLSS was the velocity maintained during the last 20 minutes of constant submaximal exercise, at which the concentration of lactate increased by no more than 1.0 mmol/L. The LMS test protocols (P1 - P5) included a warm-up period followed by a high-intensity gallop. The speed was then reduced to 4 m/s, and the incremental portion of the test was initiated. In P1, P2, and P3, the velocity increment was 0.5 m/s, and the duration of each incremental stage was three, five and seven minutes, respectively. In P4 and P5, the velocity increments were 1.0 and 1.5 m/s, respectively, and the duration of the stages was fixed at five minutes each. A second-degree polynomial function was fitted to the lactate-velocity curve, and the velocity corresponding to the lowest concentration of lactate was the LMS. RESULTS: Only the mean LMS determined by P1 and P2 did not differ from the velocity determined by the MLSS test (p > 0.1). There was a strong correlation (r >0.6) between P1 and the MLSS velocity. A limits of agreement plot revealed that the best agreement occurred between the MLSS test and P1 (mean bias = 0.14 m/s), followed by P2 (bias = -0.22 m/s). The lactate concentrations associated with the various LMS protocols did not differ. CONCLUSIONS: This study shows the variation between protocols of the LMS test for determining the onset of blood lactate accumulation but also reveals that, at least for Arabian horses, the P1 protocol of the LMS has good agreement with the MLSS.

The workload and plasma ion concentration in a training match session of high-goal (elite) polo ponies.

REASONS FOR PERFORMING STUDY: This study was designed to consider the complexity of the physical effort inherent to horses in polo competitions and the absence of reports in the literature on the effort, intensity and electrolyte changes resulting from a collective team training session aimed at preparing for a polo championship. OBJECTIVES: To determine the effort and ion changes caused by an outdoor polo training match for a 25 goal handicap (elite) based on physiological variables including acid-base status (venous pH, PCO(2) and HCO(3)(-)), packed cell volume (PCV), haemoglobin (Hb), lactate, glucose, sodium, chloride and potassium and strong ion difference (SID) as well as creatine kinase (CK) activity. METHODS: Twenty-three clinically healthy 'high-goal' polo ponies were used, which included 10 geldings and 13 females. The horses performed a training match, as a preparation for a 25 goal tournament, consisting of 6 chukkas of 7 min duration each. Blood samples were collected during resting, and at 5 min, 6 and 12 h after each chukka. Data were analysed using ANOVA for repeated measures followed by Tukey's test. RESULTS: Differences (P < 0.001) were evident mainly in post exercise for all variables studied. There was a reduction in pH, PCO(2) and HCO(3)(-) and SID, together with an increase in PCV and Hb, lactate, glucose, Na(+) and Cl(-). K(+) levels remained constant at all times of collection. The average resting value for CK was 255 ± 9 iu/l, and 6 h after effort there was a 35% increase in enzyme activity. CONCLUSIONS: This study indicates that the horses participating in a training match underwent a high-intensity effort with alterations in electrolytes and acid-base equilibrium. POTENTIAL RELEVANCE: Training matches should be carefully conducted, with a suitable recovery period before the main match.

Influência do treinamento aeróbio sobre o cortisol e glicose plasmáticos em equinos / Influence of the aerobic training on cortisol and glucose levels in horses

Estudou-se a resposta do cortisol e da glicemia em 12 equinos da raça Puro Sangue Árabe destreinados (T0) por oito meses e submetidos a um período de 90 dias de treinamento aeróbio (T90). Para avaliação dos efeitos do treinamento, empregou-se teste ergométrico constituído de exercício progressivo em esteira rolante, acompanhado por colheitas de sangue 15 segundos antes do término de cada etapa de esforço. A velocidade (intensidade) do treino foi definida como sendo 80 por cento da V4 (velocidade na qual a lactacidemia atinge 4mmol/L). Adicionalmente, no último mês de treinamento, foi instituído, uma vez por semana, exercício com velocidades variáveis, chamado "fartlek". Após 90 dias de treinamento, a concentração plasmática de cortisol elevou-se e após o teste de esforço (20min), houve aumento da glicemia. Este resultado reflete a possibilidade de adaptação ao treinamento. Conclui-se que o cortisol plasmático pode ser utilizado como ferramenta na avaliação de um programa de treinamento em equinos.

Cortisol and glucose responses were evaluated in 12 Arabian (PSA) horses submitted to a detraining period of eight months (T0) and to 90 days of aerobic training (T90). For the evaluation of the effect of training, a standardized incremental exercise test in a treadmill was used. Fifteen seconds before the ending of each effort step, blood samples were collected. The speed (intensity) of the training was defined as being 80 percent of the V4 (speed at which the blood lactate concentration reaches 4mmol/L). Additionally, in the last month of training, velocity play, a type of exercise with varying velocities called "fartlek" was instituted, once a week. Results showed that after 90 days of training, the plasmatic concentrations of cortisol and glucose increased when compared to the untrained horses. This result reflects the possibility of adaptation to the training. The blood cortisol levels may be used as a tool for the evaluation of a training program in horses.

Alterations in muscular enzymes of horses competing long-distance endurance rides under tropical climate / Alterações em enzimas musculares de cavalos em competições de enduro de longa distância em clima tropical

This study tried to monitor the alterations of muscle enzymes activity - creatinokinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) - in a group of horses that participated of 70 and 100km distance rides in five competitions of an annual endurance championship under tropical climate. Pre ride levels (U/l) were 245.13±9.84 for CK, 496.61±14.76 for LDH, and 328.95±8.65 for AST. When compared to these levels, the results revealed a significant decrease in all enzymes activities in the first moment of the rides. Peak levels, significantly different, were reached, immediately after rides by CK (413.591±50.75); 24 hours post rides by LDH (628.61±33.30); and 48 hours after rides by AST (389.89±16.96). Monitoring of recovery period revealed different behavior among enzymes activities with CK values returning to pre ride values (279.61±23.05) 24 hours post rides, while LDH and AST values returned to pre ride values (505.25±33.78 and 359.35±24.90, respectively) 72 hours post rides. These data revealed different alterations in concentration of muscular enzymes in endurance horses directly related to the duration of the effort.

Estudaram-se as alterações de atividade das enzimas musculares creatino quinase (CK), lactato desidrogenase (LDH) e aspartato aminotransferase (AST) em um grupo de cavalos que utilizados em provas de enduro de 70 e 100km de distância, em cinco competições. Os valores (U/l) basais (antes da largada) foram 245,13±9,84 para CK, 496,61±14,76 para LDH e 328,95±8,65 para AST. Todas as atividades das enzimas decresceram no primeiro momento das provas (~30km). Valores de pico, significativamente diferentes, foram alcançados para CK (413,59±50,75) imediatamente após 70km de distância; 24 horas após para LDH (628,61±33,30); e 48 horas após as provas para AST (389,89±16,96). A monitoração do período de recuperação revelou diferente comportamento entre as concentrações enzimáticas com CK retornando aos valores basais 24 horas pós-provas (279,61 ± 23,05). LDH e AST retornaram aos valores basais, 72 horas pós-provas (505,25±33,78 e 359,35±24,90, respectivamente). Os dados obtidos revelaram diferentes alterações na concentração de enzimas musculares de cavalos de enduro, diretamente relacionadas com a duração do esforço.

Blood lactate threshold reflects glucose responses in horses submitted to incremental exercise test / Limiar sangüíneo de lactato reflete a resposta da glicose em cavalos submetidos a teste de exercício progressivo

Determinou-se, em eqüinos, o efeito do treinamento sobre as concentrações sangüíneas de lactato e plasmáticas de glicose durante exercício de intensidade progressiva em esteira rolante. Demonstrou-se que o treinamento aeróbico causou diminuição da concentração máxima de lactato e que o limiar de lactato corresponde ao ponto de inflexão da curva de glicose plasmática, confirmando esse parâmetro como indicador da capacidade aeróbica de cavalos.

Aerobic training, but not creatine supplementation, alters the gluteus medius muscle.

The aim of the present study was to investigate the effect of oral supplementation of creatine on the muscular responses to aerobic training. Twelve purebred Arabian horses were submitted to aerobic training for 90 d, with and without creatine supplementation, and evaluated with respect to BW and BCS and to the area and frequency of the different types of muscle fibers in the gluteus medius. Supplementation consisted of the daily administration of 75 g of creatine monohydrate mixed into the ration for the 90 d of training. Physical conditioning was conducted on a high-performance treadmill, and training intensity was stipulated by calculating the velocity at which blood lactate reaches 4 mmol/L, determined monthly for each animal. The individual intensity of physical force at 80% of aerobic threshold was established. Morphometry of gluteus medius muscle fibers was performed on frozen sections processed for histochemical analysis of myosin adenosine triphosphatase and immunohistochemistry of slow-contracting myosin. The results demonstrated that the animals maintained a moderate BCS without alteration of BW during the course of training, providing evidence of equilibrium between food intake and caloric expenditure during the study period. The present study demonstrated that aerobic training for 90 d caused hypertrophy of fiber types I (P = 0.04), IIA (P = 0.04), and IIX (P = 0.01), as well as an increase in the relative area occupied by type I fibers (P = 0.02) at the expense of type IIX fibers (P = 0.03), resulting in modifications of the contractile and metabolic characteristics of the gluteus medius muscle. It was not possible to show any beneficial effect from creatine on the skeletal muscle characteristics examined.

Observaçöes clínicas, anatomopatológicas e tratamento de seis casos de dermovilite exsudativa vegetante crônica (cancro da ranilha) de eqüinos / Clinical aspects, anatomopathologic observations and treatment of six cases of chronic hypertrophic pododermatitis (equine canker)

Relataram-se oito casos de dermovilite exsudativa vegetante crônica em seis eqüinos de diferentes raças, com idades entre 14 meses e 19 anos. A lesäo iniciava-se pelo aparecimento de um tecido podofiloso infiltrativo na regiäo da ranilha e da sola do casco, caracterizado por crescimento rápido e desordenado, de aspecto papiliforme, de coloraçäo esbranquiçada na raiz e escura nas pontas, com secreçäo necrótica de odor extremamente fétido. Microscopicamente, observou-se a presença de exuberante tecido epidérmico proliferativo, entremeado por escasso tecido conjuntivo. Bactéria gram negativas, associadas à má higiene e umidade, estäo incluídas entre os fatores etiológicos, porém prescidem de confirmaçäo científica. Os eqüinos foram divididos em dois grupos de tratamento. No primeiro grupo, constituído de três éguas jovens e um potro, portando lesöes em apenas um membro, realizou-se inicialmente remoçäo cirúrgica da massa invasiva, seguida de cauterizaçäo das bordas restantes e posterior aplicaçäo, diária, local de substâncias anti-sépticas. Em três desses pacientes ocorreram recidivas da lesäo inicial, com rápido crescimento do tecido hiperplásico, atingindo quase toda a ranilha e metade da sola. Dois animais desenvolveram deformidades do caso, denominadas encastelamento. O segundo grupo, constituído por um macho e uma fêmea, com lesöes em dois membros, após o debridamento cirúrgico do tecido, receberam aplicaçöes diárias de ácido pícrico a 5 por cento, associado ao uso local de oxitetraciclina. Embora um desses casos tenha requerido uma segunda intervençäo cirúrgica para remoçäo da massa, os eqüinos apresentaram após um período de dois a três meses total desaparecimento do tecido infiltrativo. A utilizaçäo de ácido pícrico a 5 por cento e oxitetraciclina local associada ao debridamento cirúrgico prévio mostrou-se mais eficiente que a utilizaçäo de substâncias anti-sépticas no tratamento da dermovilite exsudativa vegetante crônica de eqüinos