Predictive interest of physiological and gait variables in French Trotters performance Pégase Mayenne - France
Introduction : French Trotters’ industry Level of performance reached by one generation (8 years of potential career) About 94 % of Trotters : lack of profitability • Huge wastage in French Trotters’ industry • Improvement in selection of horses • Development of tools of evaluation of athletic capacities
Problematic • French Trotters : middle distance runners • Racing distance : 1 600 m up to 4 400 m • High aerobic capacity • Relationships between physiological variables and performance in trotters (Roneus et al. 1999; Rasanen et al. 1995; Casini and Greppi 1996; Couroucé et al. 1997; Davie et al. 2002). • Relationships between locomotor variables and performance in trotters Bayer (1973), Barrey et al. (1995), Leleu et al. (2004) • What about young horses ?
The aim Analyse the relationships between physiological and locomotor variables measured at 2 year-old and racing performance at the end of their 4th year Any predictive interest ?
Methods • 98 two year-old born in 1999 • Physiological and locomotor test in summer 2001 • Standardisation of test conditions (track, climatic conditions, material) and training state (prepared for qualification, endurance and sprint training)
Methods : physiological test • Field exercise test • 3 steps of 3 min at increasing velocity of 500, 560 and 620 m/min • Speed and heart-rate recorded • Blood samples at the end of each step for determination of blood lactate concentration • V4 : velocity for blood lactate of 4 mmol/l • V200 : velocity for HR : 200 bpm
Methods : locomotor test Accelerometric device : Equimetrix Locomotor variables : Stride frequency Stride length Stance duration Propulsion duration Symmetry Regularity Dorso-ventral, longitudinal and lateral activities
Methods : performance indexes 2 years after the test (31/12/03): • Max ITR (Index Trot): Normal distribution (100, 20) • Earnings (€) • Best time On the basis of earnings, 4 groups of performance : • Group A : > 30 000 € (n=16) • Group B : 10 – 30 000 € (n = 26) • Group C : < 10 000 € (n= 32) • Group D : not qualified (n = 20)
Methods : Statistics • Means and sd calculated for each group • ANOVA : influence of the level of performance • Khi 2 : repartition of performance groups in the physiological groups • Matrix of correlations
Results : physiological variables V4 : 583 m/min (28) V200 : 566 m/min (37) On the basis the V4, 3 groups of horses : Group 1 : V4 > 595 m/min (n = 37) Group 2 : 560 < V4 < 595 m/min (n= 33) Group 3 : V4 < 560 m/min (n= 28)
Results : physiological variables and performance a b c d ; p < 0.05
Results : physiological variables P < 0.05
Results :distribution Performance groups (Earnings (E) at 4 y-old) Physiological groups (V4 at 2 y-old) 75 % of Group 1 : medium – good performers 75 % of group 3 : poor performers
Results : locomotor variables and performance No difference between the performance groups in gait variables No correlations between performance index and locomotor variables.
Discussion : Performance and physiological data • Relationships between lactates and racing performance in Trotters :(Casini and Greppi, 1996; Couroucé et al., 1997; Roneus et al., 1999, Davie et al., 2002; Leleu et al., 2004a) Sub-maximal vs maximal exercise Treadmill vs field Blood vs plasma lactate • Variability of athletic potential • Most studies : mature horses • Means of V4 and V200 similar to previous studies (Couroucé et al., 1999, 2002) • Measurements at 2 y–old related to performance
Discussion • Field test : Control of external factors Reproducibility of the test (Dubreucq et al., 1995) • Level of training : homogeneity (sampling) • Type of competition in France : Harnessed or mounted Distance : 2700 – 3200 m (1600 to 4400 m) Different surfaces : sand, clinker, grass Inclination More demands in aerobic capacities ?
Discussion: Gait and performance • Validation and reproducibility of gait measurements in trotters described (Leleu et al. 2002; 2004b) • Age and level of performance : factors of variation (Bayer, 1973, Barrey et al., 1995, 2001; Leleu et al., 2004c, 2004d) Age : SL, Sym, Reg and thoracic displacements in the 3 D Performance : Higher SF, relative stance and propulsion durations. • Gait characteristics at 2 y-old not related to early performance • 2 explanations : • Important modifications of gait variables during the first years of training, • limiting factors are essentially physiological at the beginning of training, locomotion becomes limiting factor in a second time.
Conclusion • No predictive interest of gait measurements • Early measurements of V4 and V200 related to performance in the 2 years following the test • Predictive interest of physiological tests • Control of important factors : test, training level. Gait Energetics
Same results in 2007 • with 200 2 y old measured • Racing performance at the age of 5.