The essential workout guide to how many reps you should be doing in the gym

5 x 5, 4 x 8 or something else entirely? Here's what you need to know about rep ranges
How many workout reps you should be doing

Open any fitness magazine or workout plan, and two ubiquitous words will stare you in the face: reps and sets. Put simply, that's the number of repetitions of a move you do and how many times you repeat that set of repetitions - for example, 10 squats repeated four times. Sounds clear enough. But why do they matter?

Obviously, you're going to need more than one push up to get your upper body strong, but the more you look into how many to do, the more complex it seems to get.

Reps and sets are another area of fitness the internet has gone wild on making overly confusing and complicated - it doesn't take much more than a cursory Google to stumble upon swarms of gym-goers arguing on forums about exactly how many reps and sets you need, and how long to rest for.

If all that gets a bit overwhelming, or if you're brand new to strength training and want to know what works best, you're in the right place. We've sifted through the research and spoken to pros, ready to give you all the info you need about how reps to do, how many times and with what weight.

Why does the number of reps I do matter?

How many reps should I do?

At the most basic level, any number of reps is better than none at all. However, if you're aiming for a particular goal then you'll want to tailor the reps you do to help guide you there. "Essentially, the number of reps and sets matter when completing resistance workouts as they lead to different results," says personal trainer Hannah Lewin.

"Generally speaking, lower rep ranges increase strength, and higher ranges increase strength endurance. Both focuses are important to ensure that you are training your body and your central nervous system effectively, essentially helping your “muscle memory” become more efficient when training."

Strength and hypertrophy

Strength is the more self-explanatory of the two. The aim of this goal is to build strength - thanks Captain Obvious over here. But what actually is strength? If this is your goal, you're looking to increase the amount of force your body can produce. That can be in the classic sense of weight lifting, or it can extend to cross-training and sport-specific workouts.

If you're a runner, you may want to strengthen your glutes and hamstrings to improve your sprinting ability. If you dance or do gymnastics, you may wish to improve your fast-twitch muscles in a similar way. For disciplines that involve competitive weight lifting, such as power lifting and CrossFit, you'll want to work on increasing your body's capability to lift heavier weights and potentially endure longer periods of doing so.

How many reps should I do?

Hypertrophy, on the other hand, is the goal of increasing muscle size. The most famous example of hypertrophy would probably be the bodybuilding community, but not all people who train for hypertrophy are looking for results quite that extreme.

If you're looking to generally train for aesthetic purposes, for example to get bigger biceps, then clearly increasing your muscle size through hypertrophy training is the way to do that – not a fake tan or posing pouch in sight. Additionally, if you're looking to target a particular muscle for injury rehab, you may be prescribed a hypertrophy style reps and sets routine. More on this later, but generally for strength, you'd do a lower number of reps with a higher weight.

If you have an inactive or lazy muscle that needs work and you dive straight into the heavy stuff, chances are your body will recruit stronger, surrounding muscles to help. Lighter weights (or even bodyweight work) with higher reps are therefore more effective for specifically targeting a lazy muscle.

How many reps should I do?

How many reps should I do?

While everyone's fitness journey is unique to their own body and its idiosyncrasies, the core elements of rep ranges remain the same. " Rep ranges, much like everything else on social media, are a total mess," says Richard Tidmarsh, personal trainer and owner of Reach Fitness. "There's information overload. You can't get away from the basics." These basics are:

  • 10 reps x 5 sets with rest = hypertrophy
  • 6 reps x 5 sets with rest = strength
  • 3 reps and under = power

"The theory of progressive overload is important here," says Lewin. "Your body adapts rather quickly to load, so it’s important to ensure that you increase intensity of your workouts over time. This can be from increasing your weights over time, decreasing rest times or increasing reps."

Does it matter how heavy I lift?

How many reps should I do?

The rep ranges you need for strength and hypertrophy guide you some way as to figuring out how heavy you need to lift. If your goal is hypertrophy, there's no point in aiming for 10 reps with a weight you can only lift for two or three.

Therefore, you'll be likely to use a lighter weight for hypertrophy than you will for strength. Likewise, for strength reps you'll be likely to use a heavier weight, but be aware of your form – it's no good grinding out a few heavy squats with terrible form. Opt for a weight that's heavy enough to challenge you but light enough that your form isn't compromised.


Don't feel like you have to stick to a particular arbitrary weight either. "Paying attention to your effort levels is hugely important," says Lewin. "The last few reps should be noticeably more difficult than the first few. If you are completing your reps at the same effort level throughout your set it may time to increase them!"

One study published in the Journal of Applied Physiology found that when men lifted at 30% of their max and 80% of their max, they gained muscle size either way as long as they lifted to failure. This is good news if you're not keen on going super heavy – you can still build hypertrophic muscle simply by maxing out.

However, the group working with a lighter weight gained less strength overall, so if your goal is to shift serious weight, then you'll have to practice lifting heavy.

Does it matter how long my rest periods are?

How many reps should I do?

You're not going to do 6 x 5 reps of heavy lifting back to back, because frankly, that would be madness. You need a break in between sets to let your heart rate settle, your hormones stabilize and your central nervous system recover enough to come back and tackle your next round. But does it actually matter how long you rest for?

One study published in the Journal of Strength and Conditioning Research found that there was no statistically significant change in the hormonal response to either two-minute or five-minute rest periods across a six-month hypertrophic training program.

Another found that untrained men who had a one-minute rest as opposed to 2.5-minute rest between sets had a greater hormonal response during the first week they trained. However, those responses had disappeared by the tenth week of training.

Rest periods and how long they last are personal to everyone, but as long as you don't leave it more than a few minutes between each set you should be on track to perform well.

I'm a beginner when it comes to strength training. What do I do?

If you're brand new to strength work then don't panic - you don't have to immediately start pounding out deadlifts at twice your bodyweight. Work with a PT to ensure you're completing bodyweight exercises with good form, then build up weight gradually so your muscles, bones and tendons can adapt. "Working in the hypertrophy zone will likely be the best idea here, as this approach will allow for both strength and endurance improvements," says Lewin.

What about workouts with rep ranges like 21-15-9 or 12-9-6-3?

If you've tried CrossFit or a metcon class, you may have come across these rep ranges as part of a workout. What's the benefit of these? "CrossFit as a sport believes that the best athlete is the one that has no weaknesses," says Gustavo Vaz Tostes, head coach at WIT Training London.

"The foundation of the CrossFit methodology will take athletes through three main pillars: functional movements, constantly varied, under high intensity. As a coach, my goal is that my athletes would be able to face any challenge that life could bring them on a daily basis. In order to do that, I will always focus on 10 physical skills when working on programmes. These are cardiovascular, strength, stamina, power, flexibility, speed, coordination, agility, balance and accuracy."

How many reps should I do?

Training all those skills in one session proves tricky though, which is why CrossFit blends elements of weight lifting, gymnastics and endurance. How does that lead to those crazy reps in WODs though?

"In pre-season, we will be doing loads of 5 x 1 or 5 x 5, or even hypertrophy sets such as 4 x 8 or 3 x 10," says Vaz Tostes. "Then we can move into heavy loads and short rep schemes. The benefit of mixed rep workouts like 21-15-9 is that in a very short period of time we can bring massive metabolic changes. Not just increase someone's aerobic capacity, but also their anaerobic, based on how many reps they can achieve in a short time."

"A great variation is that if you want to focus more on the aerobic side you can use a slightly lighter weight and less complex moves, and go for a 27-21-15-9. But in the same way, if you want to focus more on anaerobic training, you can increase weights, and decrease rep scheme, such as 12-9-6-3."

So, if you're looking to push your muscular strength and build aerobic or anaerobic capacity, CrossFit and the varied reps it uses may be for you.

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