Before we start, if you haven’t read Part I of the series looking at ‘How much cardio should I do for fat loss?’ then I suggest you quickly go back and scope it out.
Done?
Let’s jump into it.
In part 1, I referred to a relatively recent meta-analysis looking at concurrent resistance training and endurance training (cardio). [1] Within this study the authors observed that as the duration and frequency of endurance training increased, the larger the negative effect on strength, hypertrophy and power.
Based on this we could assume that doing the least amount of cardio possible would result in the best performance adaptions for resistance training and therefore a better environment to maintain/build muscle during a diet.
However, when we get to that point where we decide to include cardio into our training program, there are a number of factors to consider such as intensity, modality (type of cardio) and perhaps most importantly…personal preference.
Intensity
Over the last decade the debate over which is better, high intensity interval training (HIIT) or low intensity steady state (LISS), has raged on with valid points on both sides.
High intensity cardio has shown to provide many of the benefits of longer duration low-intensity cardio such as muscle mitochondrial biogenesis (an increase in the number of mitochondria which equals increased ATP production), increased muscle oxidative capacity and increased buffering capacity (allows us to work harder for longer), but in less time. [2,3]
Remember the interference effect from part 1? Well high intensity cardio may may reduce the amount of interference with strength training! [1]
This makes sense when we consider the energy systems used and the typical work/rest periods of HIIT training and resistance training. Both utilise the creatine phosphate and anaerobic systems primarily and involve short periods of intense work followed by a longer recovery period.
There is also the personal trainer’s favourite term; post-exercise oxygen consumption (EPOC), which is increased with high intensity cardio. EPOC in basic terms, is the energy used after exercise to bring your body back to baseline (eg. Restoring oxygen debt, metabolise lactate, phosphate re-synthesis and fatty acid cycling etc.) because during exercise the body is working extra hard and doesn't have the time to do so. [4]
So essentially for a short period after high intensity exercise there is a small increase in metabolic rate. However, this is likely exaggerated and not particularly relevant to our situation.
Why?
Studies indicate that the magnitude of EPOC is related to the intensity and duration of cardio with higher intensity and longer duration increasing the effect.[4] As discussed in part 1, this goes against our original goal of minimizing the amount of total cardio performed.
Either way it can still be seen as a small but significant benefit of high intensity cardio.
Based on the above points it would seem that high-intensity cardio is the way to go!
So the question becomes, why do LISS cardio at all?
It comes down to recovery purposes. HIIT as its name implies is high intensity. True high intensity intervals are brutal! If you find yourself able to work for longer then 20-30 seconds, then your intensity isn’t high enough.
This also means that it places a greater amount of stress on the body, which the body needs to recover from. Remember we are already weight training at a relatively high intensity, and consuming less energy while dieting.
These place stress on the body and impact recovery capabilities. If you’re still recovering from HIIT to the point that it affects your resistance training, then we have to look at other avenues.
Enter LISS.
It’s like the Louis Litt of the cardio world. Not as flashy or impressive as Harvey Spectre (HIIT) and often forgotten but still a valuable tool to consider at the right time. (If you don’t watch Suits, you need to!)
Yes, it’s tedious. Yes, there have been instances when I have spent what feels like hours on a stepper or cross-trainer only to have looked at the timer and seen 04:35 staring back at me.
But don’t be so quick to exclude it from your plans. It doesn’t place much stress on the body, can act as active recovery, can create fairly large energy deficits (with time) and if kept below 60-80% VO2 max will reduce the likelihood of negative adaptions and therefore reduce interference effect.
There is also less chance of injuring ourselves.
As Eric Helms says :
“It’s hard to make the argument that you’re retaining more muscle than the guy doing slow cardio while you’re on crutches.”
It also has the added benefit of not requiring much mental energy. For example, when I get to the stage where I need to incorporate LISS I will either listen to a podcast, read a book or even watch Netflix on my Ipad while walking on an incline, cycling or on the cross-trainer ;)
Netflix and Chill, more like Netflix and TREAD-MILL…
Terrible I know…
Modality
While intensity is one of the major components to consider, the modality used often escapes most trainee’s thoughts.
Interestingly, the mode of training we choose also plays a role in the interference effect. Unfortunately (well not for me, but for all you yoggers), there is data to indicate that running may result in greater reductions in strength and muscle growth when compared to cycling.[1,5]
This may be due to increased muscle damage from the repeated impact and eccentric actions during running compared to cycling.
We can therefore hypothesize that if cardio is to be performed, cycling or full-body exercises or circuits (eg. kettlebells, ropes, sleds etc) may be more preferable than running in order to achieve our goal of retaining max muscle and losing body fat.
Personal Preference
While the majority of this article is targeted towards optimizing your cardio protocol, personal preference acts as a zoom out function of a camera allowing us to see the overall larger picture.
That picture is this. You need to take into consideration the schedule and preferences of the individual. Hour-long moonlit walks, 40 minutes on the cross-trainer, full body circuits, or HIIT sessions. They can all be effective.
I can create a client a perfect program with just the right amount and type of cardio based off the guidelines outlined in these articles. However, if they don’t enjoy or tolerate the protocols then the client is more likely to skip sessions and decrease adherence.
Wrapping it all up!
Cardio should not be the primary tool for fat loss, regardless of the intensity or modality. The majority of your energy deficit should be created through a smart nutrition strategy.
These articles were written with the explicit goal of losing body fat while minimising muscle loss. Resistance training is the most critical aspect of that goal and should therefore be a priority, with the role of cardio being a helpful tool to use when needed but not to the detriment of resistance training.
Practical Applications:
1) Choose cardio that’s easy on the joints and results in minimal soreness in the days after. Cycling may prove better than running and full body activities can keep things interesting.
2) HIIT should be emphasized early on due to its similarities to resistance training, time efficiency and adaptions. However, individual recovery rates need to be taken into consideration.
3) Utilise HIIT 1-2 times a week with an absolute maximum of 3. These sessions should last no longer than 30 minutes with a good starting point around 18 minutes including a 3-minute warm-up/cool-down and 6 x 20 second all out efforts with 1.40 minute recovery periods.
4) If further cardio is required or due to personal preference, LISS should be incrementally added as needed. Keeping intensity below 60-70% VO2 max will help minimise any adaptions that may result in interference.
5) Personal preference should always be a key factor in what you choose. If you’re not feeling up to HIIT then a longer, easier LISS session can achieve similar body composition benefits.
References:
1) Wilson JM, Marin PJ, Rhea MR, Wilson SM, Loenneke JP, Anderson JC. Concurrent training: a meta analysis examining interference of aerobic and resistance exercise. J. Strength Cond. Res. Oct 13 2011
2) Little JP, Safdar A, Wilkin GP, Tarnopolsky MA, Gibala MJ. A practical model of low‐volume high‐intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. The Journal of physiology. 2010 Mar 15;588(6):1011-22.
3) Gibala MJ, Little JP, Van Essen M, Wilkin GP, Burgomaster KA, Safdar A, Raha S, Tarnopolsky MA. Short‐term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. The Journal of physiology. 2006 Sep 15;575(3):901-11.
4) Børsheim E, Bahr R. Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Medicine. 2003 Dec 1;33(14):1037-60.
5) Koller, A, Mair, J, Schobersberger, W, Wohlfarter, T, Haid, C, Mayr, M, Villiger, B, Frey, W, and Puschendorf, B. Effects of prolonged strenuous endurance exercise on plasma myosin heavy chain fragments and other muscular proteins. Cycling vs. running. J Sports Med Phys Fitness 38: 10–17, 1998.