The phrase 'use it or lose it' has never been more true than when applied to muscle mass. Just as we can gain muscle through appropriate exercise routines, we will gradually lose muscle if we stop training in the same way.
To answer this, it's necessary to consider how we build and maintain muscle in the first place. When we exercise, we place demands on our body, from our cardiovascular system to our muscles. Resistance training is a type of exercise which puts our muscles under stress by creating a resistance for them to work against. To cope with this extra demand, changes happen within our bodies to ensure our muscles are equipped to deal with the extra stress placed upon them.
These changes are anything from neurological adaptations to improvements in blood supply, or increases in the size of muscle fibres. The changes ensure our muscles cope more easily with the demand placed upon them, to ensure we avoid injury and continue to perform optimally. If we keep placing more and more demand on our muscles – e.g. lifting heavier and heavier weights – our muscles will continue to adapt to the extra stress.
Now reverse this and imagine taking away the demand on muscles through inactivity. Over time, this signals to the body we no longer require the ability to lift such heavy weights, as this is no longer a part of our routine. In a bid to conserve energy, our body will begin to adapt in the opposite direction, by decreasing the size of muscle fibres and reducing the blood and nutrient supply to our muscles. This results in a gradual loss of muscle mass until it plateaus at a level which best suits our day-to-day activity.
The rate at which muscle mass and strength starts to decline depends on a number of factors, from how long you have been training for and your level of muscle mass, to your age and your diet. The exact level of inactivity will also play a role in the rate of decline, as one study found men lost muscular fitness after two weeks of complete leg-immobilisation (1), whereas another study suggests muscle strength can maintain for three weeks without training (2). As a general rule a 3-4 week training break should not cause significant reductions in muscle mass and strength – but longer than this will result in a gradual decline.
The good news is, there may be such a thing as muscle memory! What this means is that we can regain our muscular fitness faster than we developed it first time around (3). So if you have trained for months to get yourself to a certain level of muscle mass and strength, but have to take a 6 week break due to injury, you should be able to get back to your pre-injury levels pretty quickly.
Where possible remain consistent with your training and avoid breaks of three weeks or more. If necessary due to commitments or fatigue for example, a 2-3 week rest period now and again is fine, but periods longer than this should be avoided.
Aim to follow a regular training program which targets all the major muscle groups – 2-3 sessions per week should be sufficient.
It's essential to keep progressing your routine to gradually increase the demand placed on your muscles. Following the same routine week after week will not only mean you won't seen any further gains, but you will likely get bored and stop working as hard. This could result in a decline in muscle mass and strength over time as the demand placed on your muscles gradually reduces.
Progress comes in the form of intensity and duration, so aim to up both or one of these to ensure you're gradually upping the demand. This means lifting heavier or working out for longer.
Your diet is essential for maintaining muscle mass. All the weightlifting in the world won't help if you are not providing your body with adequate energy and protein to help it build muscle mass. Eating too few calories can mean your body starts to break down muscle mass as a source of energy too, so it's important to eat enough calories to fuel your activity. This means avoiding very low intakes (less than 1,200) if you are being active on a regular basis. An adequate protein intake is around 0.75-1g.kg body weight for general activity, with intakes closer to 1.2-1.6g.kg being more suited to gaining muscle mass.
Overtraining is real, and inadequate rest can hinder efforts to maintain or build muscle mass. Rest days are essential to give your muscles time to repair and grow. Exactly how much rest you need does depend on the type of training you're doing and also you as an individual, but as a general rule allow at least 1-2 days recovery per muscle group. So if you train legs one day, avoid legs the next for example. Also, aim for 1-2 days of complete rest to avoid burnout.
Sleep also falls under this bracket too! This is when our body does a lot of its healing, so it's vital we get enough each night. Prioritise your 7-9 hours every night to help maintain your fitness and energy levels.
Nutritionist Emma Brown (ANutr), MSc Human Nutrition is passionate about how food science applies to the human body, and how the nutrients in what we eat affect us and ultimately have an impact on our health.