A few years ago a group of fitness researchers in both Canada and Sweden conducted a series of experiments involving combined weight training and aerobic exercise, and what they found basically overturned previous accepted theories about doing weights and aerobics at the same time.
For years the general theory among those involved in the fitness industry was that training should be separated, that is, weights should be done on one day and aerobic exercise should be done on a different day.
The theory was that doing weights and aerobics on the same day would lead to some kind of muscle confusion and therefore an ‘antagonism’ between them. So, anyone who went for a five-kilometre run in the morning shouldn’t then come back and start pushing iron, or vice versa. This is not because doing both would do any damage as such, but because the benefits of doing them separately would be better than doing them combined.
In fact, there was very little evidence for this theory, so the Swedish and Canadian studies were of great use in actually debunking this long-held theory.
Without going into the specifics of the testing by the research scientists, the bottom line was that neither study saw any evidence of the expected muscle ‘confusion’ from combining a weight and aerobic protocol.
The Karolinska Institute in Sweden stated, ‘It appears concurrent aerobic and resistance exercise may enhance the skeletal muscle anabolic environment.’ They concluded that resistance training and aerobic activity ‘can successfully be scheduled on the same day without compromising performance…’
The Canadians, at McMaster University, suggested ‘that concurrent training is as effective as either isolated mode in stimulating acute myofibrillar and mitochondrial protein synthesis rates…’
In plainer English, endurance is built on mitochondria pathways while strength is generated by myofibrils. So the Canadians were saying both strength and endurance gains were not hampered in any way by doing both activities concurrently. If you happen to be training at home with some Power blocks and then finish off by getting aboard the stationery bike for five, 10, 20 minutes or whatever, then your body will not be ‘confused’ by this in any way.
Indeed, the Swedish and Canadian researchers suggested doing both might even lead to a better long-term result that doing just one or the other on a specific day.
The bottom line is that if you happen to be in the mood or in a position to spend, say, 15 minutes going for a three-kilometre run and then you feel fresh enough to do another 15-20 minutes of weights, then go for it.
If you’d still prefer to do just one or the other on different days, then that’s fine as well.