By Dr Murray McDonald
When people talk about starting to exercise, I genuinely get excited. It’s nothing weird, I just like it when people start taking their health SERIOUSLY for once. But while the first step of simply committing to exercise is very important, it does tend to be followed by the question:
“Ok - now what?”
And fair enough. Should you be lifting weights or doing cardio? Hitting the bench or the road? And the answer, to be frank, depends on what you want.
Because your body follows the SAID Principle: Specific Adaption to Imposed Demand.
That means your body only changes to the specific stimulus under which you place it. You run, you get better at running. But running will do almost nothing to benefit your bench press. In fact, running even has limited benefit to your cycling - it’s THAT specific.
Let’s look at the differences between Weights and Cardio:
WEIGHTS
|
CARDIO
| |
Power
|
Higher
|
Lower
|
Tension/Resistance
|
Higher
|
Lower
|
Muscle Damage
|
Loaded eccentric* = High
|
Unloaded eccentric* = Low(ish)
|
Energy system
|
Anaerobic i.e. no O2 (mostly)
|
Aerobic i.e. O2 (mostly)
|
Fuel
|
Creatine / Glucose
|
Glucose / Fat
|
System targeted
|
Neuromuscular (more)
|
Cardiovascular (more)
|
*’eccentric’ contraction is when the muscle is contracting but lengthening e.g. lowering a weight
So if we know that higher tension, more muscle damage, and ‘the burn’ from short-term fuel sources running out are the main driving forces for the gun show, we can see why weights tend to make your muscles bigger (N.B. cardio also does - just less).
High oxygen needs tend to cause your heart and lungs to get bigger and better at acquiring it and your muscles more efficient at using it.
[There is considerable overlap - it’s more of a spectrum - but let’s keep it simple for now.]
So what do you want? Let’s assume you just want to be healthier and live longer (I know - crazy, right?). Which would work the best? With heart and lung disease being a very common cause of poor health, public health organizations have traditionally recommended aerobic (cardio) activity for 3-5 days per week, as it improves cardiovascular risk factors like lowering LDL cholesterol, triglycerides, waist circumference, and fat mass while increasing lung function e.g. VO2 max (a measure of cardiovascular fitness).
Research has shown that as little as 30min walking five days a week can reduce your risk of heart disease by 20%. But the important thing to note is that exercise shows what we call a “dose-response” relationship - that means that the more you do it, the better your results. Meaning that walking seven days a week or 30min jogging instead would likely be even better.
But shouldn’t that mean if you exercise constantly that you’ll live forever? Yeah, nice try - there is a ceiling on the benefits: if you exercise so much that your body can’t recover properly, you can end up injured or even become overtrained (“burn out”) which are definitely NOT healthy.
However, many health agencies have recently added some resistance training (weights) for 2 days a week to their recommendations as it shows significantly increased levels of HDL cholesterol (that’s good) and decreased blood pressure & blood glucose. But it also - very importantly - increases muscle mass and bone density, movement stability and quality of life (especially important in older folks). And if resistance training is done with only minimal rest periods between exercises, it can provide a significant improvement in cardiovascular fitness.
So where does that leave us?
Generally speaking:
- You should be active (breathing harder) for >30min on at least 5 days of the week
- Over time, try to increase how vigorous that activity is
- Include some higher resistance (weights, calisthenics*) on at least two of those days
- Get your health checked regularly to see the improvements you’re making
Easy peasy.
*calisthenics is basically using your bodyweight as resistance e.g. pushups
