Cardio, Resistance and Molecules...

Have you ever wondered what, exactly, happens to your muscles during your workout? And do you know that cardio and resistance training affect your muscles in fundamentally different ways? It’s true. In fact, how you train – cardio or lifting weights – determines if you grow.

A new study sought to test the effects of repeated sprinting and repeated resistance exercise on how muscle tissue adapts in people. Researchers had a small group of men do a one-repetition maximum (1RM) leg extension. Participants were randomly assigned to groups that either performed resistance exercise followed by sprints or vice versa. Researchers took various measurements 15 minutes and three hours after each workout session.

The results showed that repeated sprinting before weightlifting can interfere with the signals generated by weight training. Put simply, the signals generated from doing too much cardio can interfere with the signaling generated by lifting heavy weights. In this way, cardio can stop you from growing muscle.

So here’s your FUSION FACTOID: You need cardio – make no mistake – but doing too much too soon can kill your muscle gains. The solution? Try to do your cardio and weight sessions as far apart as possible to avoid signal interference. If you can’t do that, taper down the intensity near the end of your cardio session in anticipation of your heavy lifting session. Doing this well before the two-minute cooldown period will help ensure minimal signal interference.

www.fusionbodybuilding.com

Source: Coffey VG, Jemiolo B, Edge J, et al. Effect of consecutive repeated sprint and resistance exercise bouts on acute adaptive responses in human skeletal muscle. Am J Physiol Regul Integr Comp Physiol. 2009 Nov;297(5):R1441-51. Epub 2009 Aug 19.