Ok chaps, you were right... the time seems to have come where my old workout has become pointless

Ive found that now im in teh swing of it, i simply cannot run round all teh machines and hrow a few weights about as it feels like ive done sod all and i dont even break a sweat, so this week ive started to isolate areas as suggested in this room often...

Monday = Arms and Chest.
Pedal Bike (warmup)
10mins on level 6 at 90 - 100 rpm, heartrate ends around 150.

Pec Deck:
30kg x8 3 sets
45kg x8 3 sets
55kg to failure...

Lat pulldowns seated:
40Kg x8 3 sets
55Kg x8 3 sets
60kg to failure...

Tricep Pushdown:
40kg x8 2 sets
60kg x8 2 sets
70kg x8 1 sets
70kg to failure...

Tricep Curls:
40kg x8 2 sets
60kg x8 2 sets
70kg x8 1 sets
70kg to failure....

Dumbells:
Alternating Bicep curls, (18KG) 2 sets of 8
Hammer Curls, (18KG) 2 sets of 8
Side extensions, (8KG)2 sets of 8
Unsure of names of other two. Like a simple bar bell press but with dumbells, 18KG each hand.


Wednesday = Legs day:
Pedal Bike (warmup)
10mins on level 6 at 90 - 100 rpm, heartrate ends around 150.
Leg extension machine (up)
30Kg x 10 2 sets
50kg x10 4 sets
60kg to failure...

Leg extension machine (down)
40Kg x 10 2 sets
70kg x10 4 sets
80kg to failure...]

Calve press. On Horizontal leg press:
50kg x8 3 sets
70kg x8 3 sets

Leg press. Horizontal:
40kg x8 3 sets
70kg x8 3 sets
80kg to failure...


Tuesday And Thursday= CV at Gym or swim:
Pedal bike, rower, stepper, X trainer & crunches.

Friday:
??


So, the question.....
What do i do Friday? Im thinking my back, but dont really know where to start with the equiptment i have access to...

Any comments welcome on the workout listed above, bad especially welcome so i can improve