Cardio for muscle maintenance is a noisy topic. When you imagine a cardio-based athlete, or cardio junkie at your local gym, a muscular physique doesn’t spring to mind. More than likely the image of someone who loves their cardio is a slimmer person, with less muscle mass.
So, does that mean that cardio burns muscle, and thus it must be avoided? Luckily, no, and unluckily, also no.
Where did this notion that cardio burns muscle crop up from then?
This came from misinformed trainers, who saw a crude correlation between slim athletes and cardio, and hypothesised the catabolic relationship hereafter. Unsurprisingly they were not able (or willing) to properly test and prove or disprove this notion, but spread the gospel near and far nevertheless; that cardio kills muscle mass.
Cardio is also widely believed to hinder the growth of muscle mass and development of strength, but this is also not entirely true. The problem is perceived to be that building muscle requires a calorie surplus, and cardio will take you out of that necessary surplus. This could indeed happen, but is easily resolved by consuming more calories, or tapering back your cardio output. Another view is that fasted HIIT may utilise some muscle tissue for energy, which could also arguably be true.
For periods where you are trying to drop fat, you will need to be in a calorie deficit. You cannot lose 100% of the weight shed when dieting from fat stores alone – most annoyingly some will be always be from skeletal muscle too. Therefore excess cardio may push you into a greater energy (calorie) deficit, where the body will start utilising muscle mass (which is an energy expensive tissue) at a faster rate compared to a slower rate of muscle loss experienced at a lesser deficit (less aggressive diet plan).
Another way cardio could hinder muscle maintenance is by reducing our performance. Excess or very intense CV sessions may reduce your energy levels, and subsequently impede the intensity of your resistance workouts. This is an issue because reducing the weight you lift and/or the total volume (sets x reps x weight) per muscle group through fatigue, means that you will lose unnecessary muscle mass over time.
I have an inkling that I’m not selling cardio to you very well at this point. However, I would always suggest maintaining cardio in your fitness regime; regardless of whether you are bulking, cutting or simply aiming to maintain your weight.
The reason I would keep cardio an ever-present – alongside strength training – in any fitness regime, is that it can help maintain and improve overall health, fitness and performance in both sports and weightlifting. I think we can agree that there’s no point looking like Hercules if you can’t walk up a flight of stairs without breaking into a sweat, or play recreational sport without gasping for air after 10 minutes.
But how do you use cardio for muscle maintenance, or even to build muscle mass?
You can do this by being sensible with the frequency of cardio sessions per week. For instance, if I have already dropped my calories, and was previously doing no consistent cardio work, then a single cardio session would be a good addition. If you can make progress with a minimal output, which is more sustainable long term, then you should, because you can easily add more cardio if required. Essentially, we should start almost always start small and build up our intensity when required. This prevents cardio pushing you into an unnecessarily large calorie deficit, and also reduces the likelihood of impeding mental and physical performance elsewhere in your day or week.
The type of cardio session can also be important. If you have routinely sore knees, hips or back muscles, and you do a weight bearing form of cardio (running, rugby, football) the day before a legs or full body session, then it could easily hinder your lifting performance. It can do this through muscle soreness and by psychologically draining you of energy – especially for the day we all find hardest to motivate ourselves for in the gym (legs, obvs). So, I would opt for lower impact cardio discipline in closer proximity to leg day for example, and making it specific to your niggles, injuries, schedule and preferences is another good tactic longer term.
The timing of cardio in relation to your weights and meals is worth considering. If cardio comes before weights, then it will reduce energy available for lifting, and likely hinder total volume you are likely to achieve. This can also reduce coordination, and increase the likelihood of accident and or injury occurring. In addition to this, frequent and repeated bouts of high intensity fasted cardio may catabolise some muscle tissue. Thus we would suggest positioning cardio away from or immediately after weights in the same visit to the gym for maximum benefits, and also convenience and adherence. Whilst if you regularly utilise fasted cardio (which isn’t necessary or the best route to fat loss) early in the morning, we would consider supplementing with BCAAs 15-30 minutes beforehand.
In addition to the cardio suggestions above, you should track your calorie and protein intake. This way you know exactly how much energy you are consuming, and thus how to adjust your diet (or cardio regime) if you are dropping weight too fast, or not at all. Sufficient protein intake of around 1-2g per kilogram of bodyweight, will also help you repair and maintain muscle mass, which will help limit muscle loss when dieting down.
In essence, cardio is not evil, and even if used sub-optimally, it shouldn’t make any visible negative difference to your physique over the course of the average diet (6-12 weeks). Your main take homes should be:
- To try and maintain cardio year round for improved cardiovascular health and overall fitness.
- Start with the minimum effective dose, and then increase cardio volume (session frequency, output or duration) as progress stalls.
- Position cardio sessions tactically within your training regime. Taking special care not to aggravate niggles or chronic injuries, or to fatigue yourself routinely before lifting weights.
- Track the total volume you lift in your sessions. If this decreases in line with your strength, then you will lose muscle mass accordingly. Try to maintain total volume in a cut, and increase it at maintenance or when bulking.
- Track your calories; as a calorie deficit is necessary for fat loss, but too large a deficit will spare less muscle mass. You can remedy this by adding calories, or reducing your output (cardio). The same rules apply if you are struggling to gain size, which will be down to stagnant total volume, not being in a calorie surplus (which excessive cardio can also be at fault for), or both.
- The actual discipline isn’t of great importance. Find something you enjoy, as you will adhere to this more frequently. But consider if it is something that contributes to ache or injury, that it may prevent you from reaching your potential body composition.
- HIIT and LISS are both fine to do. It is the calorie burn that is most important for the majority of us. But consider supplementing with BCAAs to preserve more muscle mass if you frequently complete HIIT fasted.
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