Is it better to lift light weights with high repetition, or heavy weights with low reps?

This is a question I am often asked in classes and the answer isn't totally straightforward as there's not really a single 'best' choice, so I hope this article helps to break down the science, the practical pros and cons, and how members of 'en Joy dance fitness can use both approaches to get stronger, leaner, and more resilient.

In summary;

Answer 1. Low reps and heavy weights, or high reps with light weights - whatever you like, as long as you’re lifting!

Answer 2. It depends on your fitness goals, but for all round health and fitness it can actually be good to do both!

What are the main differences between lifting heavy weights with low reps verses light weights with high reps?

Repeated contractions with lighter loads increase muscular endurance, improve stamina, and create metabolic signals that contribute to muscle growth when sets are pushed close to failure. So, yes, light weights can certainly help you build muscle, but this technique is more ideal for muscular endurance than muscle growth, due to the sheer amount of reps it may take to reach failure. (When we talk about 'failure', it's actually a good thing when you're trying to build muscle, it is the point where you cannot physically perform any further reps while keeping the correct form and technique and the point in which you must rest). Light weights are great for combining with cardio, in classes such as Box-IT, Disco Dumbbells and Zumba Toning, where we are able to repeatedly work the muscles, building endurance while also getting a great cardio workout. These combined classes are excellent for all round fitness and helping to prevent the decline of muscle mass as we age.

Heavy weights place large mechanical loads on muscle and connective tissue, producing faster strength gains and clearer progression, which is why this method is favoured by most people wanting to build muscle, strength and power. It is also the way in which you can continue to challenge your body week after week, month after month, year after year. Your progress will be very limited by sticking with the same weights for a long period of time, and increasing reps infinitely is not really sustainable! It is always a good idea to start light and build up gradually to heavier weights, to avoid injury. Building up to using heavier weights (progressive loading) will not only help you build muscle, but you’ll also be loading the bones and therefore helping to strengthen them too, which is really important as you get older.

What does lifting weights do for bones?

We often talk about muscles and the importance of maintaining and strengthening them, but bones not so much... and we absolutely should! Small amounts of impact or pressure on the bones can ultimately help maintain them. Bone, just like muscle, is made of living tissue and responds to force placed upon it. Your body needs to be under a certain level of stress (through exercise) on a regular basis in order for bone and muscle to become stronger.

On a nutrition level, while muscle requires protein to rebuild its fibres, bones require calcium and vitamin D in order to stay healthy. Bone mass tends to decline from mid life (and quite rapidly during menopause), so it is never too early to start building up bone density, or at least aiming to maintain your bone mass as much as possible. Strong bones will help you sustain a good quality of life and independence into older age, and of course will help prevent fractures if you fall. While older adults generally won’t see a huge increase in bone density, exercise can certainly help prevent bone loss, and also of course maintain muscle mass to preserve the surrounding bone. 

What if my goal is weight loss? Won't lifting weights just make me heavier?

In short, yes, building muscle may make the weight go up slightly on the scales, or it may stay the same, but please do not take this as a bad thing. Building muscle is good for you. So, so, so incredibly good for you! What many people don't realise when they try to lose 'weight' is that they often lose muscle, especially if they are not training the muscles sufficiently. Losing muscle is not good, particularly as we get older, we want to keep hold of as much muscle mass as we can! As well as bone density, we also naturally lose muscle mass as we age, so if we fail to maintain or build muscle, we lose strength, we lose balance, and ultimately we lose quality of life. The key to a healthy relationship between food, exercise and weight loss is realising you actually just want to lose fat, not general 'weight'. And building muscle can actually help you with this.

Building muscle will not make you ‘bulky’ – unless you are specifically training, quite intensely, for that, while also following a specific nutrition plan. At ‘en Joy we don’t use super heavy weights (we wouldn't have room to store them!) and none of our group fitness classes will turn you into bodybuilder material. Building muscle will not only make you stronger, more able to carry out daily tasks such as carrying shopping bags, lifting young children, etc, but muscle also burns energy – even at rest – it is always metabolically active! So the more muscle you have, the more you’ll be increasing your body’s base metabolic rate, which is great news if your goal is fat loss or body recomposition.

Our higher intensity HIIT style sessions, such as Box-IT and Zumba+Lift, are also metabolic conditioning style workouts, combining full body movements using multiple muscle groups, which will really elevate the heart rate and can help you burn a higher amount of energy during, but also in the hours after the class, so are great if your goal is to lose fat while maintaining muscle.

The recovery process from resistance exercise also adds to your body's daily energy expenditure. Over time, building, or at least maintaining muscle mass will help with a healthy body composition, increasing the ratio of lean muscle to fat. Yes, it is a slow process but a sustainable one, much more so than any quick fix weight loss methods.

How do I know what's best for me? How heavy is heavy?!

It is very important to listen to your own body. A ‘heavy’ weight for some will be a light weight for others, and visa versa! Much of it is also down to preference – you’ll be more likely to stick with the type of workout you enjoy. You might not enjoy lifting heavy weights right now, but after a while building up you may well find that changes as you start to feel stronger. What is important is that you have control and correct form, but you need to fatigue your muscles in order to strengthen them – for some people, that will be a few reps with heavy weights, while for others it will be more reps with lighter weights, continuing until you feel you can no longer perform another repetition with proper form and control. The same rule applies for bodyweight exercises such as squats and lunges, as well as other equipment such as resistance bands – if you keep going to the point you physically can do no more with correct form, your muscles will have been working hard enough to stimulate growth.

My recommendation is that a blended approach - with both heavy and light resistance work — delivers the broadest benefits: strength, size, endurance, and long‑term resilience.

What else can I do to help my muscles grow stronger? Should I eat loads of protein?

You have probably experienced DOMS (delayed onset muscle soreness) in the days after a challenging resistance workout, but this doesn’t necessarily mean you’ve overdone it or done anything wrong. The soreness is caused by tiny microtears in the muscle tissue. (This doesn’t necessarily mean ‘no pain, no gain’, you don’t have to be aching to have worked your muscles, and you certainly shouldn’t be in pain – this could be inflammation and if you continue to workout through pain you could risk further injury). Your body will then respond by working to regenerate muscle fibres which are bigger and stronger than before. In order to rebuild these, your body does need an adequate amount of protein within a balanced diet. Too much protein will not necessarily make you any stronger, you’ll just end up consuming more overall calories than you need, especially if you are choosing sugary ‘protein’ bars etc over whole foods. While exercising to build muscle, you also need to ensure your body has sufficient energy (yes, from complex carbs!) to help preserve your lean muscle tissue from being burned to fuel your exercise.

One more very important thing is that you must allow your body to recover. Rest days are important, and adequate sleep is vital as that is when your body is able to recover and repair itself properly.

My final point is that you do have to be consistent. There is very little point in lifting weights every now and again. Muscle is much easier to lose than it is to build. To build, or even maintain muscle mass, you really do need to ‘use it, or lose it’.

Learn more about nutrition and body recomposition in our online Body Bootcamp