Here's some 'Gain only' data for my 18 yo 4* 15T Academy AML/ML, Hard Training - who's now 5*.

I can't offer any data on injuries because I've yet to get one on this player, or my high value 18yo 5* Market buy, while training.

Stretching Cardio Practice
Gain Gain Gain
56 78 156
47 77 127
43 109 121
42 79 163
48 114 159
47 102 108
46 88 157
54 73 122
41 113 165
58 119 111
54 104 134
41 80 171
51 118 128
39 74 159
37 118 122
Average 46.93 96.40 140.20