By Dr. Mercola
Short, intense workouts are all the rage in the fitness world. While it was once believed that the longer you stayed on the treadmill or elliptical machine, the better, it's now known that you can seriously maximize your fitness results while working out for a fraction of the time, as long as you sufficiently ramp up the intensity (interspersed with periods of rest).
Very short workouts, as in seven minutes or even less, are also becoming regulars in the fitness scene, although I would stop short of calling them a trend. The fact is, humans have been exercising in very short, intense bursts since the beginning, although they didn't call it exercise; they called it survival.
As such, your body is biologically programmed to respond to similarly intense bursts of activity. But because this is something many modern humans no longer do in the course of their daily grind, many are seeking it out via high-intensity interval training (HIIT).
In the video above, you can see one example of a full-body, seven-minute exercise routine by Hannah Bronfman, founder of the wellness site HBFit.
This workout is particularly useful because you can do the movements (a combination of jumping jacks, side kicks, abdominal work and more) virtually anywhere with no equipment required.
Short HIIT workouts can be deceptive, appearing simple on paper then surprising you with how challenging they are to complete. Still, a full workout in only seven minutes? Is it really too good to be true?
'Maximum Results With Minimal Investment'
Brett Klika, a performance coach for the Human Performance Institute (HPI) in Orlando, Florida, and Chris Jordan, the director of exercise physiology at the HPI, conducted a study to determine the health benefits of high-intensity circuit training (HICT), which for their study used only body weight as resistance.
Notably, they work with professionals and athletes with "incessant demands on their time," many of whom also travel frequently. They pointed out that typically aerobic and resistance training are performed on two or three nonconsecutive days each week.
For resistance training, the American College of Sports Medicine (ACSM) recommends eight to 12 repetitions, and two to four sets, for each major muscle group.
For aerobic training, 150 minutes per week of moderate-intensity exercise for 30 to 60 minutes per session and/or 75 minutes per week of vigorous-intensity exercise for 20 to 60 minutes per session are recommended.
"Although these traditional protocols can be effective, they may not be realistic enough for time-conscious adults because of the amount of time necessary to complete each program, in addition to some limitations to effectiveness demonstrated in the literature," the ACSM noted.1
As such, they developed a program that combines aerobic and resistance training, is quick (seven minutes) and can be performed anywhere, without special equipment. They wrote in the ACSM's Health & Fitness Journal:2
"Our approach combines aerobic and resistance training into a single exercise bout lasting approximately [seven] minutes. Participants can repeat the [seven]-minute bout two to three times, depending on the amount of time they have.
As body weight provides the only form of resistance, the program can be done anywhere.
HICT is not a new concept, but it is growing in popularity because of its efficiency and practicality for a time-constrained society. The combination of aerobic and resistance training in a high-intensity, limited-rest design can deliver numerous health benefits in much less time than traditional programs."
Proven Benefits of a 7-Minute Workout
The HICT program developed by Klika and Jordan was loosely based on circuit-style training that was first developed by R.E. Morgan and G.T. Anderson in 1953 at the University of Leeds in England.
Their program included nine to 12 exercises that were performed at moderate intensity for a specified number of repetitions or amount of time. Improvements in muscle strength, endurance and aerobic fitness were noted. The featured study also explained multiple benefits for their HICT workout, including:3
Fat Loss and Weight Loss
HICT involves using multiple large muscles with very little rest between sets, yielding aerobic and metabolic benefits, the latter of which may continue for up to 72 hours after the workout has been completed.
HICT may lead to greater fat loss than typical aerobics or resistance training because it increases levels of catecholamines (which increase resting energy expenditure) and human growth hormone (HGH) in your blood.
Improved VO2 Max
VO2 maxes the maximum amount of oxygen you can take in while exercising. Your VO2 max can be used as a measure of cardiovascular endurance. "When HICT protocols have been compare with traditional steady state protocols in the laboratory, HICT elicits similar and sometimes greater gains in VO2 max despite significantly lower exercise volume," they wrote.4
Decreased Insulin Resistance
Research supports the use of HICT (and HIIT) for reducing insulin resistance, which is a contributing factor in the development of type 2 diabetes. Unfit but otherwise healthy middle-aged adults were able to improve their insulin sensitivity and blood sugar regulation after just two weeks of such training (three sessions per week).5
A follow-up study also found that HIIT positively impacted insulin sensitivity. The study involved people with type 2 diabetes, and just one session was able to improve blood sugar regulation for the next 24 hours.6 Kilka and Jordan added, "Positive changes have been observed in insulin resistance in as little as eight minutes per week when executed at an intensity more than 100 [percent] VO2 max."7
12 Exercises in 7 Minutes
You may now be wondering what, exactly, Kilka and Jordan's sample HICT program entails. The exercises were designed to:
✓ Promote strength development for all major muscle groups
✓ Use large muscle groups to create resistance and aerobic intensity
✓ Create a balance of strength throughout your body
✓ Be immediately modified or adapted as necessary to increase or decrease intensity
✓ Be safe and appropriate for participants
✓ Be interactive with features of the training environment, such as stairs and walls)
✓ Be easily transitioned to accommodate minimized rest time
You can watch a demonstration of the exercise sequence in the video above, and they're also described below. Each exercise is performed for about 30 seconds with 10-seconds allowed for transitions. This adds up to an approximately seven-minute workout, which may be repeated in its entirety two or three times. The exercises should be done in the order given, as they're selected to allow opposing muscle groups to alternate between resting and working.
1. Jumping jacks (total body)
2. Wall sit (lower body)
3. Pushup (upper body)
4. Abdominal crunch (core)
5. Step-up onto chair (total body)
6. Squat (lower body)
7. Triceps dip on chair (upper body)
8. Plank (core)
9. High knees/running in place (total body)
10. Lunge (lower body)
11. Pushup and rotation (upper body)
12. Side plank (core)
As Intensity Increases, Duration Decreases
How many times you should repeat the seven-minute workout (one to three times, max) depends on a variety of factors, including intensity. The harder you work, the shorter your workout should be.
Research has shown proven benefits, including improvements in VO2 max and insulin sensitivity in just four minutes of HIIT exercise. However, to achieve these benefits, you likely need to be working at an intensity that's equal to or greater than 100 percent of your VO2 max.8
This is a level of intensity that many people may not be able to achieve or maintain, especially if you're just starting out. During a typical HIIT workout, the American Council on Exercise (ACE) notes, "Training is done at a submaximal level; around 80 to 95 percent of maximal aerobic capacity."9
In other words, on an exertion scale of 1 to 10, a typical moderate-intensity workout (such as running or stair climbing) would be an exertion level of 5 to 6. A typical HIIT workout is done at an exertion level of 7 or higher. Very short HIIT workouts, such as Tabata Training, are an exertion level of 10.
The good thing about HIIT is that you can tweak it to your needs. You can still get benefits from working out at a slightly lower intensity; you simply increase the time you work out to make up for it. You'll still be working out very intensely, remember, so your total workout will still be short, relatively speaking.
I typically recommend an HIIT session of 20 minutes. If you were using the protocol above, you could therefore repeat it three times. According to the featured study:10
"More moderate protocols (90 [percent] to 100 [percent] of VO2 max) have been examined for various total exercise durations. Although these protocols seem to require slightly more total exercise time to be effective, they still are well below the steady state exercise time requirements.
Because most individuals may not be able to execute the program at an intensity significantly greater than 100 [percent] of their VO2 max following the established ACSM guidelines for high-intensity exercise of at least 20 minutes is recommended. This may require multiple repetitions (or circuits) of a multistation exercise circuit."
If You Think You're Too Busy to Exercise, HIIT Is for You
Lack of time is one of the most common excuses used for not exercising. HIIT removes this hurdle, because virtually everyone can squeeze in seven minutes. If you have a bit more time, and you're performing the workout at less than 100 percent, try repeating it two or three times.
With this minimum time investment, you'll likely enjoy decreased body fat, improved insulin sensitivity and muscle strength and increased VO2 max. As Kilka and Jordan noted, "Individuals who previously believed that they did not have the time for exercise can now trade total exercise time for total exercise effort and get similar or better health and fitness benefits."11