'Channing was in decent shape when I started working with him but like a lot of guys, he likes to eat fast food and sink a few drinks,' says William J Harris, the New York-based personal trainer who helped the up and coming movie star get in shape for Fighting.

Bulking up, however, wasn’t on the agenda. ‘Channing didn't need to get bigger,’ says Harris. ‘In fact, we wanted him to shed some weight to make him look more agile, more like a fighter. The programme I devised help him shift 13.6kg in the three weeks before filming started.’

But rocking up to the set looking like a waif wouldn’t work either. ‘He needed to have strength, flexibility and endurance so I came up with a routine of rope turns and callisthenic bodyweight exercises, such as jumping jacks, burpees, press-ups, pull-ups and squats, to help him build that. I also threw in some classic compound moves using barbells and kettlebells.’

Tatum was given three exercises to perform each session and had to complete as many 'rounds' as he could within 20 minutes. 'Working out at a high intensity keeps the heart pumping and burns more calories,' says Harris. 'For the main barbell lifts, such as deadlifts, military presses, squats and clean and jerks, we found a weight Channing could lift quickly and comfortably ten times while maintaining perfect form.’

‘We changed what we did every session to keep his mind engaged and his body guessing,’ Harris says. 'I put him through a three-day-on, one-day-off routine and kept workouts to just 30 minutes. If you keep the intensity high you don't need to train for any longer than that.'
 
If you're more concerned with putting on muscle than burning fat, add more weight to these lifts and focus on completing four rounds in the session, rather than as many as you can in 20 minutes.

Day One
Warm-up – Five-minute jog.
Main workout – 20 minutes to do as many rounds as possible of 100 rope skips, 10 pull-ups and five clean and jerks.
Cool down – Five-minute light jog and stretching.
 
Day Two
Warm-up – Five-minutes of skipping.
Main workout – 20 minutes to do as many rounds as possible of 20 burpees, 15 hanging leg raises and 20 bodyweight squats.
Cool down – Five minutes of skipping and stretching.
 
Day Three
Warm-up – Five minutes of skipping.
Main workout – 20 minutes to do as many rounds as possible of 400m sprints, 10 kettlebell swings and 10 press-ups.
Cool down – Five-minute light jog and stretching.
 
Day Four
Rest day before starting the routine again. To avoid getting bored during the following weeks, mix up the exercises from different sessions or include some of the additional ones listed below, but leave at least one day's rest between exercises that work the same muscle groups.

Other exercises to do:
25 burpees
75 press-ups
50 sit-ups
25 box jumps
Five deadlifts
50 walking lunges
20 jumping jacks
Five military press
10 bench press

If you want guides to performing the above moves, go to the exercise section of our site.

Tatum's daily diet
Harris was responsible for Tatum’s diet, too. 'Just as exercise is all about intensity, food is all about quality,’ says Harris. ‘So we swapped the unhealthy ingredients in the food Channing likes for healthy ones – we gave him lean turkey rather than beef, for example, and swapped takeaway pizzas for homemade wholewheat ones topped with organic veggies. Processed and frozen foods, salt, sugar and alcohol were all no-nos.’
 
Breakfast: Omelette with veg, wholewheat toast and an orange.
Snack: Apple and unsalted nuts.
Lunch: Grilled chicken breasts, spinach and sweet potato.
Snack: Cottage cheese and mixed nuts.
Dinner: Turkey burger with mixed veg.
Snack: Yoghurt and a handful of almonds.

If you want to add serious bulk a la Hugh Jackman in X-Men Origins: Wolverine, have a gander at this exclusive Wolverine workout we got from his trainer Michael Ryan.

For more movie workouts, check out the mag. You can try three issues for £1 here.