Generalized linear mixed model fit by maximum likelihood (Laplace
  Approximation) [glmerMod]
 Family: Negative Binomial(9.1498)  ( log )
Formula: Velocity ~ Sex + Bodymass + Starttime + Trainingsday * Trial +  
    Age + (1 | ID)
   Data: data

     AIC      BIC   logLik deviance df.resid 
  5248.2   5303.9  -2612.1   5224.2      757 

Scaled residuals: 
       Min         1Q     Median         3Q        Max 
-2.3867379 -0.6691812 -0.0243646  0.6495992  3.9505065 

Random effects:
 Groups Name        Variance   Std.Dev.
 ID     (Intercept) 0.03466785 0.186193
Number of obs: 769, groups:  ID, 52

Fixed effects:
                                      Estimate    Std. Error  z value
(Intercept)                        2.312163998   0.218781604 10.56837
Sexm                              -0.106357551   0.060679876 -1.75276
Bodymass                          -0.002235682   0.001636927 -1.36578
Starttime                        191.226049568  22.099344146  8.65302
TrainingsdayFirst Training        -1.120096596   0.160168508 -6.99324
TrainingsdayLast Training          0.198222140   0.086827964  2.28293
Trial                              0.008858310   0.016037817  0.55234
Age                                0.002213329   0.002320432  0.95384
TrainingsdayFirst Training:Trial   0.187402713   0.081463773  2.30044
TrainingsdayLast Training:Trial   -0.095806294   0.019861022 -4.82384
                                   Pr(>|z|)    
(Intercept)                      < 2.22e-16 ***
Sexm                               0.079642 .  
Bodymass                           0.172008    
Starttime                        < 2.22e-16 ***
TrainingsdayFirst Training       2.6861e-12 ***
TrainingsdayLast Training          0.022435 *  
Trial                              0.580716    
Age                                0.340163    
TrainingsdayFirst Training:Trial   0.021423 *  
TrainingsdayLast Training:Trial  1.4082e-06 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Correlation of Fixed Effects:
            (Intr) Sexm   Bdymss Strttm TrnnFT TrnnLT Trial  Age    TrFT:T
Sexm        -0.192                                                        
Bodymass    -0.304 -0.093                                                 
Starttime   -0.488  0.010  0.001                                          
TrnngsdyFrT -0.403  0.026  0.017  0.027                                   
TrnngsdyLsT -0.507  0.053 -0.152  0.001  0.417                            
Trial       -0.224 -0.020  0.007 -0.001  0.304  0.556                     
Age         -0.533  0.125 -0.506  0.071  0.339  0.538  0.003              
TrnngsdFT:T  0.049  0.016 -0.079 -0.007 -0.830 -0.084 -0.198  0.064       
TrnngsdLT:T  0.185  0.021 -0.022  0.006 -0.246 -0.743 -0.807  0.003  0.160
fit warnings:
Some predictor variables are on very different scales: consider rescaling
optimizer (Nelder_Mead) convergence code: 0 (OK)
Model is nearly unidentifiable: very large eigenvalue
 - Rescale variables?
Model is nearly unidentifiable: large eigenvalue ratio
 - Rescale variables?