The Benefits of Doing Both Weights and Cardio

Weights and cardio together?

Let's start with the hardcore scientific facts: weights and cardio don't go well together.

This is because they both compete to make your body a certain way; when you perform endurance cardio together with strength training, muscle growth, strength, and explosiveness are reduced.

Basically, your body wants to adapt only way one or the other. Gym-goers call too much cardio with weights "losing your gains", scientists call it the concurrent training effect, or the "interference effect."

Your muscle fibre types actually change depending on the type of training you do, and the signalling pathways prefer one direction or the other.

The enzyme AMPK and PKB (protein kinase B/Akt) both fight each other and want two different things:

PKB: Reduces protein breakdown and activates protein synthesis (good for muscle growth).

AMPK: Increases glucose transport and mitochondrial protein; ideal for increases in endurance and cardiorespiratory fitness.

The pair simply block the signalling of one another. 

But is this really a bad thing?

I argue it depends on your goals.

I know many health and fitness fanatics who love the benefits from endurance training:

- Improved metabolism.
- Reduction of cardiovascular risk.
- Reduced all-cause and cardiovascular mortality.
- Improved cardiorespiratory fitness.
- Improved mental health.

Now they are some great benefits!

And they combine it with resistance training to also increase strength and to grow some muscle mass in conjunction with their endurance work.

But one of the big things here is mental health, whilst resistance training improves mental health too, a fresh study argues for combining both resistance training and endurance training!

Executed right here in Australia in 2020, the researchers analysed the data of 1.48 million American adults for seven years, 18 per cent of whom had been diagnosed with depression. They reported:

"A physical activity routine that includes both aerobic and MSA (muscle-strengthening activity) is likely to be optimal for the prevention of depression."

So, there's a strong argument for combining both!

But this is when we ask ourselves the question: why do we partake in exercise?

If you're a bodybuilder looking for maximal muscle size, then obviously endurance cardio is not your optimal strategy.

But if you're someone passionate about great mental health, cardiorespiratory fitness, and some muscle mass to boot, then combining both strength and endurance training is a great idea, even if it slightly reduces the potential outcomes of both.

Moreover, if you wanted to try a form of cardio that doesn't hinder muscle growth, then HIIT is a great idea; you don't see many skinny sprinters!

But take it easy if you're in a very low-calorie deficit with HIIT as recovery can become very difficult.

HIIT also offers up many cardiorespiratory fitness benefits, though some might find it harder to perform than endurance exercise. It really comes down to personal preference.

However, if you want to combine both cardio and weights together, there is a way to do it to reduce the negative effects; try them on different days or cardio after lifting.

This recent review showed weights before cardio is better for strength improvement compared to doing it after. 

And if you want to just lose weight, then you can do it without cardio! 

Fat loss is simply governed by a calorie deficit. And, whether or not you create a deficit from dieting or from a combination of diet and exercise; your fat loss results will be the same.

The bottom line is that whilst endurance cardio and weight training interfere with one another, there's a strong argument for doing both. It comes down to what your goals are with your training and what outcomes you want. For maximal muscle growth, resistance training only is the best bet. But with the mental health benefits from combing both endurance cardio and weights, that option is terrific, in concert with the other cardiorespiratory benefits not seen in resistance training alone. If weight loss is the goal, it can be achieved without exercise.