Likely the most popular form of aerobic/cardiovascular exercise is running. The sport has, in recent years, seen a surge in participants. From 1991 to 2011 the number of runners finishing official events increased from just over 5 million to almost 14 million![i] If these runners are anything like the runners I know, their love of the sport leaves little room for other exercise (even for the rest of us, it’s a time-consuming endeavor!). Let me be clear, however, I love running, and usually get in 3 or 4 good runs per week. And when I was marathon training I too did little else. Optimal health, however, must include anaerobic/resistance training.
One of the biggest challenges in the fitness industry is convincing people of just how important resistant training is; we haven't done a very good job, as for many, resistance training is still a fringe discipline only for the extreme athletes (thank you, Schwarzenegger). But avoiding resistance training is a BIG mistake, here is why.
Optimizing strength gains
While running is an excellent method for improving cardiovascular performance (heart and lung health) it does not stress the musculoskeletal system adequately, resulting in little strength gain[ii]. The point of resistance exercise is to stress the body so that it has to adapt and get stronger. It adapts by breaking down and rebuilding the affected muscles.
*warning – science talk!* There are many mechanisms in the process of musculoskeletal adaptations, one of which is hormonal; the release of testosterone and human growth hormone (HGH), to name a couple. The greatest response for hormone release occurs when the exercise utilizes large muscle groups comprised of fast-twitch muscle fibres, which are recruited for explosive/strength movement. When these fast twitch muscle fibres are recruited and damaged on a microscopic level (the nature of exercise) it generates increased levels of both testosterone and HGH .
Additionally, as we get older our levels of these hormones tend to decrease (making it harder to stimulate their release). This makes it more important to include resistance training in your workout as you get past 30.
Activating these fibres can be done via resistance training or interval/sprint training. With heavy weights type 2 fibres are utilized – especially if it involved larger muscle groups (e.g. back rows would generate a greater hormonal response than bicep curls). Additionally, while they may seem similar mechanically sprinting and jogging are quite different. The former is a strength exercise utilizing fast-twitch muscle fibres resulting in a greater hormonal response. Sprinting (running or biking) for 30 seconds and taking an active break (continuing at a slower pace) for 90 seconds is also effective.
Improving Joint health
In order for joints to receive nutrients there must be adequate compression. Cartilage for example, has no micro-vascular supply of its own. Therefore, the normal process of diffusion of nutrients is supplemented by the convection induced by cyclic compression and release during joint usage. In other words, move your joints with adequate resistance.
The lower body joints may be adequately stressed with aerobic exercise (for running, not so much on recumbent bikes) but in all likelihood the upper body joints do not. Resistance exercise improves joint health more than aerobic exercise, especially for upper body extremities. This is also why it’s general preferred that exercises be done standing whenever possible rather than sitting or lying down (as it loads the skeletal system).
Aerobic exercise can adversely affect the positive effects of Anaerobic exercise
Potential loss of lean mass: Research shows definitively that aerobic/endurance exercise will eventually burn protein as a fuel source. Of course, this is counter-productive to strength improvement goals.
Potential dysfunction/imbalance from repeated patterns without complimentary movements.
As Lee Boyce writes on mensfitness.com:
Above all, however, always lift weights more often than doing cardio. The repeated impact of running, linear motion of biking, swimming or rowing, and endless creations of the same movement pattern and ROM can create muscle imbalances over time that can lead to joint problems. A smart resistance training program can at least counter these effects – so be wise and make cardio supplement your weight training.[iii]
Resistance training does not have negative effects on cardiovascular health
There is no evidence that resistance training adversely effects cardiovascular improvement.
Any well designed program for adults will emphasize resistance training first, with a complimentary amount of cardiovascular work.
Again, Lee Boyce writes on mensfitness.com:
Here’s the catch – only performing steady state cardio can be counterproductive - Too much steady state cardio per week can result in muscle loss. Having said that, seek alternate methods that involve a bit more explosive movement to utilize your strongest muscle fibers available. A half hour of sprints (or even better - hill sprints), intervals, or a solid round of basketball, tennis, or football can be just what the doctor ordered.iii
Summary
- Cardio does not adequately stress the musculoskeletal system resulting in minimal strength gain/joint improvement.
- Cardio can burn lean mass as a fuel source - resulting in strength loss.
- Resistance training does not adversely affect cardiovascular health.
Solutions
- Keep your cardio workout short-medium - the rule of thumb I use is to keep my aerobic sessions to 60 minutes or less. Longer bouts are when you run the risk of burning lean mass for fuel.
- Space them out - do your resistance training sessions on a separate day or 6 hours apart from your aerobic workout.
- Run intervals – alternate between short bouts of sprinting with active recovery (slower running). However, this still won’t do much for upper body health.
- Introduce an aerobic/cardiovascular component to your resistance exercise program – lighter weights, more reps and less rest between sets. However, be leery of going to light – as the system must be adequately stressed in order to be forced to get stronger. Aim for a resistance that allows you to do about 12 reps but not much more. If you could have kept going then you need to add resistance.
Lastly, if you’re going to do cardio and resistance in the same session it’s better to do resistance training BEFORE cardio (contrary to common practice). For more on this see my forthcoming blog on common mistakes.
Cheers and happy training!
[i] http://calorielab.com/news/2013/03/18/running-grows-in-popularity-again-infographic/
[ii] Aerobic exercise stresses the musculoskeletal system more than sitting on the couch, to be certain :-)
[iii] http://www.mensfitness.com/training/cardio/trainer-qa-cardio-vs-weight-training
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