UPGRADE your thinking as well as your work-outs in 2015 with my guide to the new rules of fitness.

So swap the running machine for a rower, drop the heavy weights for a lighter touch and change your rep speed to get on the fast track to good form.

1.The new way to build muscle

Conventional thinking: To build muscle, lift huge weights.

New thinking: Let large dumbbells gather dust.

A new study has found the same degree of muscle building can be gained by using light weights.

Use it: Most people use weights 80-90 per cent of the most weight they can push once, usually doing 5-10 reps. This study proves you can do 30 per cent, average 25 reps, and still build muscle.

2. The new way to burn fat

Conventional thinking: Doing 3-5 sets on each exercise will burn extra calories.

New thinking: Less is more.

Research found one set is as good as three sets at raising the amount of calories you burn for up to three days after your work-out.

Use it: Rather than do a thorough warm-up before weightlifting, repeat a circuit once using the most weight you can manage on each exercise. Come away drenched.

3. 2015’s finest fitness machines

Conventional thinking: Running machines are the best calorie burners.

New thinking: Elliptical trainers and rowers are the top tech.

Elliptical trainers burn as many calories as the treadmill. If you are injury-prone, rowers solve that problem. The movement is soft on the joints and if done correctly, you can clock up a huge calorie burn.

Use it: Ditch the rails and pump your arms while holding a light dumbbell in each hand. “Row flat out for 45 seconds, rest for 45. Repeat this eight times, take two minutes recovery.”

4. How to focus your work-outs

Conventional thinking: Do an exercise to isolate every muscle group.

New thinking: Do strong-man moves as part of a full-body work-out.

You can’t isolate each muscle because they tend to help one another out in each lift, so you’re better off doing full-body work-outs.

Use it: Pair a lower-body exercise (squat: six reps) with an upper-body one (bench press) to create lots of lactic acid, a great fat-burner/muscle-builder. Rest for 10 seconds after squat, then do the bench; take 60 seconds before repeating three times. Pick three more pairs.

5. The new pace to work out

Conventional thinking: To grow, your lifting speed should be slow.

New thinking: Tailor your lifting speed to your goals.

Research in the Journal Of Strength and Conditioning Research discovered that surges of your muscle-building hormones such as testosterone and IGF-1 were the same for both speeds.

Use it: Varying your lifting speed is an excellent way of building both muscle and strength. Alternate between a week of fast reps (one second up, one down) and a week of slow reps (two seconds up, four down) for more muscle, a bigger calorie burn and improved sports performance.