Do you need more reps or heavier weights to tone up? Fitness expert settles the debate

It's an age-old debate for fitness junkies. What's better for building muscle - lifting heavier, or more frequently? 

Now, fitness professionals have attempted to settle the question of reps vs weight for good.

According to Amanda Place, a personal trainer and founder of the UK-based coaching firm Sculptrition,  if you want to boost the size and strength of your muscles, a relatively short-lived workout will do the trick.

But it won't be an easy one. 

She explains: 'If you aim to maximize muscle size and strength, lifting heavier weights with lower repetitions is the preferred approach, as it promotes hypertrophy and significant muscle growth.'

Doing many repetitions with lighter weights can help you build endurance

Ali Malik, a personal trainer and founder of UK-based boutique gym Fitness Labs explained to Stylist that this is a 'fundamental principle in strength training and exercise science'.

'It involves gradually increasing the demands placed on your muscles, typically by lifting heavier weights or increasing resistance overtime,' she says.

This leads to muscular hypertrophy, or growth. 

According to the University of New Mexico, the strain of lifting heavy weights causes tiny tears in your muscle cells, which the body promptly comes in to repair. 

When your body repairs these tears, it adds new tissue on top of the old, slowly growing the amount of muscle you have over time, and making the whole system stronger. 

Malik adds: 'Progressive overload [increasingly heavier weights] also requires increased joint stability and muscle activation, which can help to protect against joint injuries and enhance overall joint health.'

You should increase your weight to as much as you can handle without compromising your form, Malik explained. Discomfort is okay, but if you're feeling intense, sharp pain, it could be a sign that you're seriously hurting your body by lifting with bad form. 

'The effects of increasing weight without proper form may result in serious injuries, especially for strength-building exercises that may put a strain on your spine,' Malik said.

But increasing repetitions has different benefits, and is also an important part of a weights workout, experts say.

'Working in a higher rep range helps to improve the ability of your muscles to perform over an extended period,' explains Ali Malik.

'Performing more reps with shorter rest intervals can also elevate your heart rate and enhance cardiovascular conditioning.'

Doing fewer repetitions with higher weight can help you build bigger muscles

The real sweet spot is a combination of them both, because that way you can get cardiovascular benefits from the high-rep workout while increasing muscle mass.

This concept, known in the research community as periodization, has been around since at least the 1950's, and can help you achieve weight loss and muscle growth without hitting a progress plateau, according to George Mason University. 

In order to find a balance between heavy-lifting and high-rep, you should pay attention to when your workouts start to feel too easy, Malik said. 

If you're breezing through, 'hitting the top of your rep range during your sets with proper form can be a sign to go up in weight,' he said. 

Some of the common endurance exercises you can incorporate into your workout

Some popular heavy weight lifting exercises  barbell squats, bench press and shoulder press.