From here: http://builtblog.wikidbody.com/2007/06/11/how-to-do-cardio-if-you-must/
How to do Cardio if you MUST!


We don’t do the same lifting workouts all the time – why should cardio be any different?

HIIT – High Intensity Interval Training
HIIT is a protocol of alternating high and low intensity exercise, for example sprint/walk intervals.

Research has shown a number of physique-enhancing benefits to HIIT:

• “High intensity training may prove beneficial if used properly. For example, its potent stimulation of whole body lipolysis during exercise leads to a rapid influx of plasma free fatty acids after intensity is lowered. In this context, it is postulated that performing a notably short, high intensity session, followed by a long duration, low to moderate intensity workout, may optimize lipid oxidation.” (4)

By following HIIT with a little steady state cardio, you’ll oxidize mobilized FFAs so they don’t re-esterify into triglyceride and hang around. Cool eh?

• In fact, HIIT may actually curtail the propensity for fat storage:

”…it is highly probable that sprinting-evoked, systemic AMPk activation simultaneously curtails an individual’s natural genetic propensity for fat-storage as well. This is because, in response to the rapid ATP-depletion prompted by those repeated, maximal-intensity bouts of anaerobic expenditure, AMPk also works to curtail Acyl-coenzyme A: diacylglycerol acyltransferase (DGAT1) activity and glucose uptake into adipocytes.

This saves ATP for energy repletion rather than having it “misallocated” to synthesize new triacylglycerol (TAG) in your adipocytes. (5)

• HIIT has a higher EPOC (excess post-exercise oxygen consumption) than steady state cardio.

• It leads to rapid improvements in VO2max and endurance performance (6) – this means you’ll perform better lifting workouts, too.

• It doesn’t promote the conversion of type IIb (the so-called “pure” fast-twitch muscles) to type IIa slow-twitch analogues (7) (see below, steady-state cardio discussion).

• And it can help increase carbohydrate metabolism, which can improve nutrient partitioning. (

HIIT doesn’t “work” by burning off fat – it works by stimulating catecholamines (9), and catecholamines strongly stimulate lipolysis in mammals. Plasma fatty acid concentrations increase dramatically immediately after intense exercise, where fatty-acid oxidation decreases. That’s why you do some steady state cardio at the end.
How often: If you’re going to do any cardio, do HIIT at least once and at most three times a week. Ideally, do it either on its own day, or on a leg day at least 6-8 hours away from your workout.If you must do it in the same session as your workout, do it right after, on a leg day. Although this may seem counterintuitive, HIIT is quite the leg workout. Doing HIIT on upper body days may compromise recovery since your legs will have less time to rest.What to eat: Because of the strong anaerobic component, feed HIIT the same as you would a lifting workout – target some carbohydrate and protein to provide an available pool of amino acids and to stimulate the cortisol-blunting insulin response.

For those of us whose diets are lower in carbs, you’ll want a little carb in you pre-workout or you WON’T be able to give these sprints your all, much like a lifting workout. If your carb consumption is ample, just focus on post-HIIT carbs. At least one study showed that post-workout carbs/protein didn’t impact FFA burning post-exercise: “in the post-exercise recovery period, muscle glycogen resynthesis has high metabolic priority, resulting in post-exercise lipid combustion despite a high carbohydrate intake”. (10) So your post-workout shake with dextrose is fine here.

Hill Repeats

“Hill training is excellent for improving maximal oxygen uptake because both high heart rate and high systolic pressure (the multiplication of these factors is known as the “rate-pressure product”) are achieved, and these components stimulate left ventricular hypertrophy and vascular development.”

“When doing full-fledged in-season work at VO2max, your aim should be to create a session which can blend in favourably with other sessions and races and which allows you to accumulate enough time to provide a viable stimulus for improvement without overdoing it.

Avoiding overkill basically means minimizing the negative effects of acidosis, so that your movements remain efficient, muscle groups are recruited in harmonious concert, and aerobic energy production dominates your efforts as long as possible. This is best achieved if you orchestrate the rest intervals between bouts so as to allow adequate recovery while also keeping the circulatory system active, thus reducing the possibility of “venous pooling” and allowing for some lactate to be reconverted to other metabolites by the heart and skeletal muscles.” (13)

“Those who run on hills have also been shown to be less likely to lose fitness when they take time off from training. And many scientists believe that hill training can improve the elasticity of muscles, tendons and ligaments, allowing these tissues to carry out more work with less effort and fatigue…Other research, carried out by Dr. Bengt Saltin, discovered that runners who trained on hills have much higher concentrations of aerobic enzymes - the chemicals which allow your muscles to function at high intensity for long periods without fatigue - in their quadriceps muscles than those who did all their running on flat terrain.” (14) So, well-conditioned ligamefnts and tendons in leg muscles that are resistant to fatigue – all good things for those of us who do a lot of heavy squats!

“One of the objectives for longer interval training is to improve the body’s ability to function in the presence of lactate. The higher level of effort raises the body’s energy demand beyond what can be generated through primarily aerobic metabolism, and the anaerobic systems become more important. The body’s aerobic energy systems are much more efficient than the anaerobic systems, but have a limited rate of energy release. Training for endurance sports, such as marathons or triathlons, focus on developing the body’s cardiovascular system to increase its aerobic capacity, and also on increasing the lactate threshold, which allows sustained physical effort at a higher, partially anaerobic level.

During incline or pace intervals, you’re moving the body’s energy production in and out of mostly aerobic and mostly anaerobic modes” (15)

Hill “repeats” performed in this manner burn a lot of calories, because they force the larger muscles of your body (i.e. glutes) to do more work. They improve exercise economy as much as exhaustive distance training (16) but may help you avoid the disadvantageous fibre-conversion problems associated with extended steady state cardio.

“Economy is measured during the aerobic endurance test on the treadmill and is expressed simply as the volume of oxygen (VO2), relative to your body weight (ml/kg/min), that your body requires in order to run at a sub maximal speed. It is therefore a measure of the “cost of the body’s movement” during each stage of the test.” (17) Now, as a lazy person, the word economy makes me nervous – makes me feel like I’m becoming an economy car. But wait: “As well as running for sufficient distances, running economy may also be improved by hill running or strength training. In particular, explosive strength training which includes sprinting, jumping and weight training using high to maximal movement speeds and low loads (up to 40% of 1 repetition maximum) can improve running economy.” So, since weight training can improve running economy anyway, it’s probably not worth worrying about for hill repeats performed once a week during a cut, okay?

Summarizing – we get to burn a lot of calories without needing to be fed extra calories or carbohydrate for the task. We improve the heart stroke, so resting heart rate goes down like it does with extended, boring steady state cardio, possibly with less risk of fibre-type conversion.

Increased heart stroke volume means increased VO2 and hence more oxygen circulating through your body. Lactic acid is a result of anaerobic metabolism (i.e. lifting), so with faster lactic acid clearance from the improved VO2 max, you’ll experience less fatigue you’ll lower the rate of lactic acid build-up.

(Low Intensity) Steady State Cardio

The good

Steady State (SS) cardio is often over-stressed and may be over-rated as a principal exercise modality, but it isn’t entirely useless. Research has shown that capillary density increases with low intensity cardio (19), and that means better blood supply to the muscles. It also translates to improved lipid profiles, possibly because of the improved glucose uptake due to this improvement in blood supply. And it can be helpful as a form of active recovery from more intense forms of activity. (20)

When trained subjects were tested at 25%, 65%, and 85% of maximal oxygen consumption (VO2max), plasma glucose tissue uptake and muscle glycogen oxidation increased in relation to exercise intensity, while peripheral lipolysis was stimulated maximally at the lowest exercise intensity. (21)

Furthermore, low-intensity steady-state cardio isn’t particularly taxing to the body’s resources, an important consideration for athletes looking at avoiding overtraining, particularly in a caloric deficit.

The bad

That being said, while SS cardio is not particularly catabolic, it doesn’t create much of a caloric deficit. There is also an increased risk of repetitive strain injury (talk to any marathon runner). And there is evidence that extended endurance training promotes a transition from type II to type I muscle fibre types. (22) This is one REALLY important reason why it is so important to incorporate other types of cardiovascular training into your programme.

Endurance training has another ugly side – although fat oxidation increases in trained athletes, with conditioning, more and more of this fat comes from muscle triglyceride (23) – meaning less and less comes from adipose tissue. It seems the body learns to store muscle triglyceride where it’s being used (24), so it’s available for energy more quickly that it would be from adipose tissue – a phenomenon Charles Poliquin so eloquently describes as “Kobe beef thighs and butt, all plump and marbled with fat inside”.

Conclusion: endurance training is less and less likely to lean you out as you get used to it.

And the ugly

Steady State cardio sessions of up to 60 minutes a day can be used as an option to drop calories further as your cut progresses. To alleviate boredom and introduce still more complexity, these can be split up into separate sessions on the same day or divided amongst different modalities – for example, 20 minutes of incline treadmill, 20 minutes of stair climbing, 20 minutes of cycling.

How often: Ohhh, this is a tough one. For physique goals, my gut says 3 hours a week at the most. If you’re doing more than this to lose weight, look first to your diet, then to different forms of cardio, such as HIIT and hill-repeats. If it’s because you enjoy it, well, I’m sorry, but I’m far too lazy to understand you. Maybe try to watch more TV…?

What to eat: Because SS cardio uses fat as the primary fuel substrate, it doesn’t require any particular feeding paradigms. On days with SS cardio, eat as you would have otherwise.

Post workout SS cardio

For the same reason as was found by Romijn et al (25) in the HIIT summary above, SS cardio following a lifting workout may burn off FFAs mobilized by the intense lifting.

It can also act as active recovery and a means of burning off accumulated lactic acid as a fuel (26), protecting the muscles from ensuing hardness, which, while temporarily attractive, may leave the athlete more prone to injury. As a final note, Cressey suggests the improved nutrient delivery and clearance of metabolic wastes (27) afforded by increased capillary density due to steady-state cardiovascular conditioning may serve to reduce DOMS (28) (delayed onset muscle soreness) – so all you exercise-masochists will have to find something else to enjoy about your killer workouts!