After a 4-month hiatus due to lockdown restrictions, gyms are set to reopen across the UK this coming Saturday (25^th July) - welcome news for those eager to return to their pre-lockdown exercise routines.

Alas, many of us will have curtailed our training during the past few months, exercising less or even stopping altogether. According to a survey of 2,000 people by the British Heart Foundation, 25% of responders have been doing less exercise since lockdown was imposed in the UK on March 23^rd.

Even if we’ve maintained our previous training frequency, we may have nevertheless significantly altered the types of exercise that we do. For instance, unable to access squat racks, rowing ergs and Smith machines, we’ve perhaps placed greater emphasis on light cardio (e.g. walking, running, cycling) and bodyweight exercises that require minimal equipment. If it hasn’t deteriorated then, our fitness will have likely changed over lockdown.

Add to the mix that your local gym will now have radically changed its layout to comply with social distancing guidelines, and the prospect of returning to the gym may seem daunting. But it need not be a baptism of fire.

In this article, we’ll highlight what happens to your body when you take a long break from exercise before providing some tips to ease your transition back to the gym.

What happens to our body when we take a long break from exercise?

‍

Whenever we exercise, we expose our body to physical stress. If we do this on a regular basis, our bodies compensate by making all sorts of changes to our muscles, nerves, connective tissue, and overall metabolism. These so-called training adaptations enhance our athletic performance and include things such as: increased cross-sectional area of muscle fibers, laying down of new capillaries to improve blood supply to muscles, higher bone mineral density, and improved motor neuron excitability.

Unfortunately, such training adaptations are not permanent. If we stop exercising or dramatically reduce our exercise intensity and frequency, we gradually start to lose them. This is known as the principle of reversibility, neatly summed up by the adage “Use it or lose it.” As a result of this reversal of training adaptations, our fitness and exercise performance drops – a phenomenon referred to as detraining.

Some changes that occur during detraining include:

• A decline in VO2 max (a measure of aerobic fitness). Studies suggest that short term detraining (i.e. less than 4 weeks of reduced / no training) leads to a 4-14% drop in VO2max.

• A drop in blood volume. This reduces the amount of blood pumped out with each heartbeat to working muscles, resulting in poorer exercise performance. A drop in blood volume is thought to occur within just 2 days of inactivity.

• Poorer insulin sensitivity. Exercise stimulates our muscles to produce more of a transport protein known as GLUT4. In response to insulin, this transport protein facilitates the uptake of glucose from the bloodstream into muscle cells, where it can then be burned for energy or stored as glycogen. In just 6-10 days without exercise, muscle GLUT4 levels decrease by 17-33%, resulting in reduced insulin sensitivity.

• Changes in muscle fibre size and composition. Long term detraining (i.e. more than 4 weeks of reduced / no training) is shown to alter our proportion of slow-twitch (Type I) and fast-twitch (Type IIa and IIx) muscle fibres. Generally speaking, detraining leads to a shift away from Type I to Type IIa fibres, and a shift from Type IIa (fast oxidative) to Type IIx (fast glycolytic) fibres. Furthermore, long periods of inactivity shrink the cross-sectional area of muscle fibres.

• Reduced muscle strength. The bad news is that it’s hard to cling on to those well-earned strength gains if we stop exercising. The good news, however, is that our strength subsides less than you may think. An 8-12 week period of inactivity is associated with only a 7-12 % reduction in force production.

So, with the above in mind, how should we approach our return to the gym in order to regain training adaptations and fitness?

1. Don't forget to warm up

‍

It’ll come as no surprise, but warming up before a workout prepares our body for movement, promotes blood flow to exercising muscles, and reduces our risk of injury: something which is particularly important after a long period of inactivity.

The American College of Sports Medicine recommends at least 5 – 10 minutes of warm up before your main exercise session.

In terms of what to do during warm-up, the current evidence suggests that dynamic warm up exercises involving movement are much better than static stretching. On this note, a systematic review of 31 studies found that high-load dynamic warm-ups are best for upper body strength and power performance, whereas short-duration static stretching had no effect.

Similarly, passive warming/cooling techniques, such as taking a hot bath or sitting in the sun, are also ineffective.

2. Start off slowly

‍

Tempting as it may be, it isn’t advisable to dive straight back into your old, pre-lockdown workout routine. As discussed earlier, inactivity leads to the loss of many training adaptations, leaving your body initially unprimed for exercise intensities to which it was once accustomed.

Resuming high intensity exercise straight away is likely to cause greater muscle damage, prolong recovery time, and increases the risk of injury. Accordingly, you should dial back the intensity of your workout.

But what exactly does that mean?

For cardio it’s pretty self-explanatory. If you’re on a treadmill, reduce the speed. If you’re on an exercise bike, lower the resistance.

For strength training, avoid lifting heavy straight away. Many of you will already know your pre-lockdown 1RM or one-rep max: the maximum weight you can lift for one repetition. When returning to the gym after a long break, it’s worth limiting yourself to between 50 and 70% of your 1RM.

In future sessions, you can then gradually ramp up the weight. According to the American College of Sports Medicine, when training at a particular repetition max load, increase the weight by between 2-10% only when you’re able to perform the current workload for one to two repetitions over the desired number. In other words, if, for example, you can currently perform a maximum of 10 reps using a 20 kg weight, wait until you can comfortably perform 11-12 reps before increasing the weight (to between 20.4 – 22 kg).

In addition to reducing the weight/load, you may also want to start off with a lower number of reps. Aim to keep a few “reps in reserve” when performing strength exercises. This concept means that, if absolutely pushed, you could do a few more reps of that exercise – which, of course, you won’t do, as you’ll be taking things easy at beginning!

3. Prepare for muscle soreness

‍

If you haven’t exercised a particular muscle group in a while, expect those muscles to be sore for about 12 - 72 hours after your workout. This phenomenon, which you’ve no doubt experienced before, is known as Delayed Onset Muscle Soreness (DOMS).

DOMS is thought to result from microtears sustained by muscle fibres, followed by inflammation as the muscle tissue is remodelled. Unfortunately, by virtue of our genetics, some of us may be more susceptible to excessive inflammation following exercise. This may lead to greater exercise-induced muscle damage and longer recovery times.

You can find out more about your genetic susceptibility to exercise-induced muscle damage, as well as tips to moderate the inflammatory response, in your Muscle Damage (TNF-α trait).

Depending on your ACTN3 genotype, you may also be more likely to experience muscle damage and soreness after eccentric exercise. Eccentric contraction refers to contraction of a muscle while it is lengthening. For example, if you were to resist gravity on the downward motion of a bicep curl, your bicep muscle will be lengthening as it contracts.

None of the above is to say that you should be disheartened by muscle soreness or that you should avoid eccentric exercise altogether. In fact, due to something known as the repeated bout effect, after an initial bout of eccentric exercise, we can expect to experience less muscle damage and soreness with subsequent bouts of exercise.

‍

4. Optimise your post-workout nutrition

‍

In order to enhance your recovery between workouts, it’s important to make sure you’re eating correctly. According to the International Society of Sports Nutrition (ISSN), carbohydrates and protein are particularly important after exercise in order to stimulate synthesis of glycogen and muscle protein synthesis, respectively.

Carbohydrates

If you’re exercising moderately, you will typically require about 3 - 5 g / kg bodyweight of carbohydrates per day. If you’re exercising quite heavily (e.g. 2–3 h per day of intense exercise, 5–6 times per week), you’ll need more carbohydrate in your diet - about 5 – 8 g / kg bodyweight each day.

The timing of your carbohydrate intake is also important to optimise the synthesis of glycogen – our muscles’ main energy store. Aim to get some carbs on board within the first few hours following exercise.

Protein

Consuming protein before or after strength training has been shown to stimulate muscle protein synthesis (MPS) – the key process driving increases in strength and size of muscles. You can read more about MPS in the Muscle Hypertrophy (mTOR) trait article.

For most of us doing moderate workouts in the gym, a protein intake of 1.4 – 2.0 g / kg bodyweight per day will suffice. For people with a highly-experienced background in resistance training, there’s evidence to suggest that higher protein intakes (>3 g / kg / day) can help maintain muscle mass while promoting fat loss.

If you’re taking an acute protein dose (e.g. a protein shake) after a workout, aim for an absolute dose of between 20 - 40 g. Ideally this should contain 700 – 3000 mg of leucine, as well as other essential amino acids (EAAs). Leucine in particular is known to stimulate MPS.

Micronutrients and supplements

Various micronutrients (found both in foods and supplements) may also help to minimise long term inflammation levels and enhance recovery from exercise. You can find out more about what to eat to reduce chronic levels of inflammation in your Inflammation and IL-6 levels trait.

5. Be patient

‍

Remember that it takes time for your body to lay down new training adaptations in response to exercise. As such, don’t expect to see fitness and strength gains straight away.

The good news, however, is that we do tend to regain fitness quite quickly – which may be due to a kind of molecular muscle memory, whereby our muscle cells “remember” previous workouts. One small study showed that after 30-32 weeks of inactivity (detraining), it took just 6 weeks of retraining to get back to previous strength.

Bear in mind though that the ability to regain strength and aerobic fitness depends on several factors, one of which is our age. Studies of older adults (aged 65 and over) undergoing 12 months of detraining reported that it took 3 months of retraining to regain upper and lower limb strength, and over 9 months to regain aerobic fitness.

Our gene variants also play a role in our propensity to gain muscle too. As you can find out in your Muscle growth (IGF-1) and  Muscle hypertrophy (mTOR) traits, you may be lucky enough to be to build muscle more easily.