Training abdominals with cardio seems like a natural fit intuitively. Whether it’s just the “feel good” factor or a more physiological scientific reason, the two modalities combine well.
Unlike combining cardio and weight training, the goal of cardio and abs training is often to lose fat. More specifically, to lose fat near the core, that which is comprised of the abdominal muscles, obliques, and lower back.
It’s not uncommon to see someone perform a few sets of crunches and planks before hopping on the treadmill with the intent of targeting fat loss.
We are often told that you can’t target fat loss. Many people tend to hold fat in their abdominal region, so naturally they would want to lose fat where they store it the most. The practice of attempting to lose fat in a specific region is called spot reduction.
The refuted claim has merit, since fat loss is systemic. In other words, burning fat is a multi step process where fatty acids are taken from a seemingly random location in the body, circulate the blood, and enter the muscle cell before they are converted to energy.
Systemic fat loss makes logical sense when you think about it. If you’ve ever seen an obese individual lose a great deal of weight, you may notice that their face gets leaner. But it’s not as if they were doing facial exercises or chewing gum vigorously, it’s just evidence of how fat is lost overall. It is lost from all parts of the body.
Carbohydrates, on the other hand, are stored in the muscle. The muscle performing an exercise will preferentially use the stored carbohydrates, also known as glycogen, in that very muscle. If you are performing a bicep curl, you are likely using glycogen stored in the bicep to perform the contraction.
But is there a way to influence where fat is lost?
Many studies have said no, but some had flawed designs, whether it was in the methods or the measurements.
For example, some studies will have participants train one body part but not another, to see if fat loss is greater in the trained muscle. The conclusion was often no, but in many cases there was no fat loss overall. How can you compare fat loss between body parts if there is none to begin with?
In addition, the studies were for resistance training only. We want to look at the combination of resistance training and cardio.
A recent study looked at the relationship between exercise and cardio to see if fat loss could be targeted to a certain degree. Individuals were separated into two groups; one did lower body training followed by cardio, the other did upper body training followed by cardio.
The lower body group lost more fat in their legs while the upper body group lost more fat in the upper region. The great thing about this study was that both groups lost significant body fat, which made it easier to measure.
In addition, both groups still lost fat in the non-exercised portions of the body, but fat loss was proportionally higher in the regions that were being worked. Based on this study, we can hypothesize that performing abs before a cardio session may be more beneficial for fat loss in the stomach area.
The proposed mechanism for why abs before cardio is the better method is quite simple. Performing resistance exercise brings blood to the muscle being worked. With that potentially comes the liberation of fatty acids from body fat.
Fat is stored in adipose tissue as triglycerides. A triglyceride is composed of 3 fatty acids held together by a glycerol backbone. In order to burn body fat, those fatty acids must separate and enter the bloodstream.
Performing cardio after abs can help oxidize, or burn, fat that has been liberated from said fat tissue. This is via the cardio itself, increases in temperature, and regulation of hormones that burn fat.
For this to occur, the abs training and cardio must be intense. You can’t expect to lose abdominal fat from a set of planks and a 10 minute walk. The best way to do so is probably through high intensity interval training (HIIT) or at the very least moderate intensity steady state (MISS) training.
HIIT can take many forms so long as it features a series of high intensity exercise followed by low intensity exercise, or in some cases just rest. The differences between HIIT and low intensity steady state cardio (LISS) are outlined here.
With the abdominal exercises themselves, don’t hesitate to do some weight bearing movements like cable crunches or weighted decline sit-ups, provided you are able to handle it.
The idea is to get significant blood flow to the abdominal area before the cardio session. Doing this requires adequate tension on the core. Sometimes the typical body weight exercises for abs aren’t enough to achieve this. Don’t be afraid to use supersets or high repetition sets to ensure the program is working.