What is Exercise Snacking? How it is different and potentially better than other exercise? What health & fitness goals is it suited to? Why might you choose to experiment with it? These are the questions I am going to answer within this post.
If you are convinced to give it a go and want a guide on how jump to Exercise Snacking How To Guide.
Exercise Snacking Goals & Results shares my personal experience of Exercise Snacking for eight weeks. Read that for a deep dive into my goals, approach, outcomes and reflections.
Caveats first. I am fit, healthy and have been exercising regularly for most of my life. I have qualified as a personal trainer but have limited practical experience of training others. I am neither a physical training expert nor a physician. Everything I share therefore is offered as a starting point for your own thinking and discussion with experts you trust. Exercise performed poorly can discourage or injure you. Safety first.
What is Exercise Snacking? 4-Hour Body Version
I came across the concept of Exercise Snacking within 4-Hour Body by Tim Ferriss. Tim presents exercise snacking as a “biohack”. A biohack is a practice intended to deliver some specific physical or mental benefit or both.
The exercise snack biohack described by Tim is a short and intense burst of exercise prior to a large meal. Tim’s own exercise snack consists of 90 seconds of body weight exercises, air squats, a chest press motion and a back rowing motion. The intended benefit of exercise snacking prior to a large meal is to favour muscle over fat gain following the meal. The reason Tim thinks this might be effective is rather complex. The short version reads like this:
- Intense Exercise activates production of a transport protein called “GLUT-4”
- GLUT-4 regulars blood glucose transport to muscle and fat cells
- More GLUT-4 results in more blood glucose being transported into muscle cells and less to fat cells
Quoting from Tim
The more muscular gates we have open before insulin triggers the same GLUT-4 on the surface of fat cells, the more we can put in muscle instead of fat
Tim does offer one study in support of this biohack. The study was performed on rats and used an exercise duration of 280 seconds. Tim is a bestselling author and I am an unknown blogger. I reckon Tim has some crazy good ideas and some crazy ideas. I am unsure which bucket this one falls into. The idea intrigued me enough to add to my “find out more” list and potentially give it a personal trial. As a result of both of those things I believe there may be some value in the practice depending on your specific goals.
What is Exercise Snacking? Wider reading version
Exercise Snacking has much in common with more familiar forms of exercise and activity for which there is extensive evidence of health and fitness benefits. It is similar to High Intensity Training (HIT), High Intensity Interval Training (HIIT), Sprint Interval Training (SIT), Peripheral Heart Action Training (PHAT) and the Burst Training promoted by Dr. Axe.
It might be better to think about what Exercise Snacking is an alternative to. Short bursts of vigorous Exercise Snacking are an alternative to longer and continuos periods of low intensity steady state (LISS) or moderate intensity steady state (MISS) exercise. These cover most forms of aerobic activity such as jogging, cycling, rowing, ergo-training and circuit training with light resistance.
Tim Ferriss proposes Exercise Snacking specifically as a ‘biohack’ for use prior to very high calorie meals eaten once per week. In contrast I have experimented with Exercise Snacking as part of a holistic body composition and fitness regimen. This matters a lot as these goals are very different. There is strong positive evidence for the effectiveness of Exercise Snacking for general health and fitness benefits. The evidence for the ‘biohack’ is fascinating but far more speculative.
Exercise Snacking Compare & Contrast
Below I offer a highly simplified comparison between Exercise Snacking and both similar and different forms of exercise. The information is shared from a Google Sheet set for Public Access. You can also view it directly in Google Drive by clicking here.
So why do Exercise Snacking?
I share why I personally chose to experiment with Exercise Snacking within Exercise Snacking Goals & Results. That post also covers why I am confident it ‘works’ for me. Why should you use it? Here are the are the top reasons.
#1 Similar results in less time
Assuming you exercise for health benefits rather than for enjoyment alone Exercise Snacking might free up time you can use to enjoy other things. If short bursts of vigorous exercise are manageable for you and provide similar fitness and body composition benefits to exercise that takes far longer why not do it?
#2 Practicality & Simplicity
In addition to time liberation the exercises performed within Exercise Snacking can be done just about anywhere and anytime. At home, work, during travel for business or vacation. Exercise Snacking is easy because there are plenty of suitable exercises that require little or no equipment at all and do not even require you to change clothes or shower. Combine this with the short duration and you have exercise you can very easily fit into a daily routine. Got 10 minutes? You can probably complete an Exercise Snack!
Exercise Snacking How To Guide covers several easy ways to practice Exercise Snacking. I reckon there is at least one for everyone!
#3 Reduced risk
Assuming you can exercise at vigorous intensity and perform movements properly and safely using Exercise Snacking is a way of getting a ‘minimum effective dose’ of exercise. That means just enough for you to enjoy health and fitness benefits but thanks to the low volume, reduced risk. Specifically, reduced risk of overuse injury, reduced long term wear on your joints, tendons and connective tissues and reduced inflammation and stress from training.
#4 Break up of sedentary time
Exercise is essential for better health but so too is reduction of extended periods of time spent being inactive. Independent of physical fitness and activity extended periods of doing nothing are associated with poorer health and all cause mortality. Running 10k on the weekend is great but does not prevent damage done by sitting still at a desk most of the day every day in the week.
Exercise Snacking can be used to break up inactive time and prevent harm. There is extremely convincing evidence for the independent benefits of both exercise and reduction of sedentary time for major health risks and all cause mortality.
#5 Blood Glucose and Insulin Control
There is very specific and compelling evidence showing that brief periods of intense activity prior to meals are an effective method to moderate the blood glucose response to the meal and support insulin sensitivity. This is of value to most people and not just those with diabetes or pre-diabetes. Insulin sensitivity is good. Insulin resistance is bad.
#6 Glut-4 Activation
Well it *might* work! If anyone has tried this or knows of any evidence or knows of any way to test the theory I would love to know about it. I am a volunteer study participant given the right protocol!
Why not do Exercise Snacking?
Opposing the good reasons to use Exercise Snacking there are some very good reasons not to use it too.
#1 Injury Risk
Yes, I featured reduced risk as a benefit too but the big caveat is about the safety of ‘vigorous effort’. For maximum results in minimal time Exercise Snacking requires vigorous effort. Suitable exercises, including body-weight based moves such as Squats, Presses and Rows need to be performed properly to avoid risk of injury. Sprinting and jumping can easily and painfully strain muscles and connective tissues.
If you are beginning an exercise routine from a sedentary and untrained starting point the combination of vigorous exertion and the need for good form make Exercise Snacking a potentially risky practice.
This is not exactly a reason not to use Exercise Snacking. Instead it is a reason to use it sensibly and safely. Start out slow and if you are new to exercise get some skilled instruction on how to perform exercises safely. This will set you up for success and independence.
#2 Sport Specificity
If you train to enhance performance for a sport Exercise Snacking may well not help you perform better. It will make demands on your total recovery and adaptation capacity. It may even negatively impact on your sporting performance if it competes with more focused activity matched to the particular demands of your sport.
If for example I were a competitive swimmer, power-lifter, gymnast or sprinter I highly doubt that Exercise Snacking would be something helpful in addition to the highly demanding needs for my sport. Exercise Snacking is probably ideally suited to the general population. People who are not athletes and who do not have a very physically demanding job. That still makes it a great candidate for most!
#3 Training Overload
Exercise Snacks will contribute to overall training load and recovery need. If you use them as your primary form of Exercise, no problem. If you layer them on top of an existing regimen they might just be too much and slow or reverse progress towards your goals. I write this as a 40+ year old very mindful of recovery ability. I recommend this excellent article covering How Much Cardio You Should Do and How Much is Too Much?
Similarly if you have existing activity that offers a combination of exercise and pleasure such as many team and competitive sports Exercise Snacking may simply not be as much fun! They are arguably best suited to general fitness and well-being goals for non-athletes. That still makes them an excellent option for most people.
How to do Exercise Snacking?
What does science say about Exercise Snacking?
Short answer? Science says a lot, and what it says makes very clear that Exercise Snacking offers many benefits.
There is a wealth of research into the outcomes of short bursts of intense activity including comparison and contrast with lower intensity steady state alternatives. Most of the research does not use the specific term ‘Exercise Snacking’. However this reflects that Exercise Snacking can itself refer to many different things. If you see research covering things like High Intensity Interval Training or Sprint Interval Training or ‘Minimum Effective Dose’ of exercise it may well have something interesting to say about Exercise Snacking.
What follows is a highly selective ‘pick & mix’ list of relevant studies lending credibility to Exercise Snacking as an effective way to pursue various health and fitness goals. There are links to every article for those with the appetite to delve into the detail and a key quote takeaway.
Headline: Less Time for Similar Results
This was an intervention study with young active male subjects. It observed ” . . . similar increases in muscle oxidative capacity . . . and protein content . . .” and concluded that “Given the large difference in training volume, these data demonstrate that sprint intervals training is a time-efficient strategy to induce rapid adaptations in skeletal muscle and exercise performance that are comparable to endurance training in young active men”
“High Intensity Interval Training is more effective at improving . . . vascular function than moderate intensity continuous training”. “Four intervals of 4 minutes at 85-95% maximum heart rate three times per week for at least 12 weeks is a powerful form of exercise to enhance vascular function”
Note the very sensible caveat about HIIT relative to lower intensity exercise is that high intensity may present greater risk of injury and adverse effects.
“High Intensity Interval Training is superior to moderate intensity continuous training in improving cardiorespiratory fitness in participants of cardiac rehabilitation” and “HIIT appears to be as safe as Moderate Intensity Cardiorespiratory Training (MICT) for cardiac rehabilitation participants”
Headline: Diabetes and Blood Glucose Control
” . . . for those who can tolerate it, exercise at higher intensity may offer superior fitness benefits”
“We examined the effects of a 1-h bout of morning exercise versus intermittent walking bouts of short duration on glucose excursions and insulin secretion over 12-h. Short, frequent periods of exercise attenuated glucose excursions and insulin concentrations in obese individuals to a greater degree than an equal amount of exercise performed continuously in the morning”
“Dosing exercise as brief, intense ‘exercise snacks’ before main meals is a time-efficient and effective approach to improve glycaemic control in individuals with insulin resistance.”
“Two weeks of sprint interval training increased insulin sensitivity up to 3 days postintervention. Twelve weeks near maximal interval running (total exercise time 40 minutes/week) improved BG to a similar extent as running at 65% VO2max for 150 minutes/week”
Headline: Minimum Effective Dose
“Just two 10-second to 20-second “all-out” efforts performed three times per week was found to promote changes in insulin sensitivity and aerobic fitness, while offering huge time savings”
“A total of only two minutes of sprint interval exercise was sufficient to elicit similar responses as 30 minutes of continuous moderate-intensity aerobic exercise”
Analysis of 13 individual studies comparing high with moderate intensity exercise concluded that both showed similar effectiveness for positive impacts on body composition measures. The high intensity protocols required 40% less time suggesting that HIIT may offer the advantage of a far more time-efficient protocol.
” . . . a training programme based on a brief bout of high-intensity exercise, which lasted <10 min per session including warm-up, and performed three times per week for 6 weeks, improved peak oxygen uptake in young healthy subjects”
“Low-volume HIT produces moderate improvements in the aerobic power of active non-athletic and sedentary subjects”
Headline: Breaking Sedentary Time
“proportion of sedentary time was strongly related to metabolic risk, independent of physical activity” and “older people may benefit from reducing total sedentary time and avoiding prolonged periods of sedentary time by increasing the number of breaks during sedentary time”
“Prolonged sedentary time was independently associated with deleterious health outcomes regardless of physical activity”
Headline: Reduced All Cause Mortality
“Both sustained and short burst exercise delivery health benefits so long as intensity and total duration are sufficient” and “Moderate-to-vigorous workouts reduce mortality, even in short bursts under 10 minutes”
Headline: Glut-4 Activation
Okay, you have read this far, wow! Congratulations! So here are some rodent and sled dog studies that might, if findings are relevant for humans, indicate that the Tim Ferriss ‘biohack’ could work as hoped. Why no human studies? Well Glut-4 is best measured by taking a muscle biopsy and that means literally taking away some muscle fibers. Not the kind of thing humans are generally signing up for!
First a primer on what Glut-4 actually is . . .
Glucose transporter type 4 (GLUT-4) is the insulin-regulated glucose transporter found primarily in fat and muscle. Insulin-stimulated glucose uptake is primarily mediated by GLUT4. levels increase rapidly in response to exercise training and involved in the energy uptake response to aerobic exercise. Muscle contraction stimulates muscle cells to translocate GLUT4 receptors to their surfaces.
“8 days of HIT lasting only 280 s elevated both GLUT-4 content and maximal glucose transport activity in rat skeletal muscle to a level similar to that attained after LIT, which has been considered a tool to increase GLUT-4 content maximally”
“Both insulin and exercise acutely stimulate GLUT4 recruitment to the cell surfaces of muscle and adipose cells”
” . . . investigation demonstrated that acute high-intensity exercise increased GLUT4 . . . of sled dogs”
” . . . high-intensity training was more effective for increasing GLUT4 content and glycaemia reduction . . . “
In conclusion, exercise at approximately 40 and approximately 80% V(O2 peak), with total work equal, increased GLUT4 mRNA and GLUT4 protein in human skeletal muscle to a similar extent, despite differences in exercise intensity and duration.
Ready to Give it a Go?
Great, ready to go? You could very literally begin Exercise Snacking today. It is quick and super simple to begin. Get started by reading Exercise Snacking How To Guide or review my personal goals and results at Exercise Snacking Goals & Results. Within the latter I explain and share a ‘Quantified Self’ approach to setting meaningful goals and using Exercise Snacking to pursue them
Already Exercise Snacking? Tell me about it! Why? How? Need some suggestions? Ask me about it!
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