Don't Have Time to Exercise? Here's 7 Reason You Should Try HIIT
By Dr. Grant Tinsley
While most people know that physical activity is healthy, it's estimated that about 30 percent of people worldwide don't get enough (1).
Unless you have a physically demanding job, a dedicated fitness routine is likely your best bet for getting active.
If this sounds like you, maybe it's time to try high-intensity interval training (HIIT).
HIIT is a broad term for workouts that involve short periods of intense exercise alternated with recovery periods.
One of the biggest advantages of HIIT is that you can get maximal health benefits in minimal time.
This article explains what HIIT is and examines seven of its top health benefits.
What Is High-Intensity Interval Training?
Typically, a HIIT workout will range from 10 to 30 minutes in duration.
The actual activity being performed varies but can include sprinting, biking, jump rope or other body weight exercises.
For example, a HIIT workout using a stationary exercise bike could consist of 30 seconds of cycling as fast as possible against high resistance, followed by several minutes of slow, easy cycling with low resistance.
This would be considered one "round" or "repetition" of HIIT, and you would typically complete 4 to 6 repetitions in one workout.
The specific amount of time you exercise and recover will vary based on the activity you choose and how intensely you are exercising.
Regardless of how it is implemented, high-intensity intervals should involve short periods of vigorous exercise that make your heart rate speed up (8).
Not only does HIIT provide the benefits of longer-duration exercise in a much shorter amount of time — it may also provide some unique health benefits (4).
How to Get Started With HIIT
There are many ways to add high-intensity intervals to your exercise routine, so it isn't hard to get started.
To begin, you just need to choose your activity (running, biking, jumping, etc.).
Then, you can experiment with different durations of exercise and recovery, or how long you are performing intense exercise and how long you are recovering.
Here are a few simple examples of HIIT workouts:
- Using a stationary bike, pedal as hard and fast as possible for 30 seconds. Then, pedal at a slow, easy pace for two to four minutes. Repeat this pattern for 15 to 30 minutes.
- After jogging to warm up, sprint as fast as you can for 15 seconds. Then, walk or jog at a slow pace for one to two minutes. Repeat this pattern for 10 to 20 minutes.
- Perform squat jumps (video) as quickly as possible for 30 to 90 seconds. Then, stand or walk for 30 to 90 seconds. Repeat this pattern for 10 to 20 minutes.
While these examples can get you started, you should modify your own routine based on your own preferences.
Summary: There are many ways to implement HIIT into your exercise routine. Experiment to find which routine is best for you.
The Bottom Line
High-intensity interval training is a very efficient way to exercise, and may help you burn more calories than you would with other forms of exercise.
Some of the calories burned from high-intensity intervals come from a higher metabolism, which lasts for hours after exercise.
Overall, HIIT produces many of the same health benefits as other forms of exercise in a shorter amount of time.
These benefits include lower body fat, heart rate and blood pressure. HIIT may also help lower blood sugar and improve insulin sensitivity.
So, if you are short on time and want to get active, consider trying high-intensity interval training.
Here are the seven top health benefits of HIIT:
HIIT Can Burn a Lot of Calories in a Short Amount of Time
One study compared the calories burned during 30 minutes each of HIIT, weight training, running and biking.
The researchers found that HIIT burned 25–30 percent more calories than the other forms of exercise (9).
In this study, a HIIT repetition consisted of 20 seconds of maximal effort, followed by 40 seconds of rest.
This means that the participants were actually only exercising for 1/3 of the time that the running and biking groups were.
Although each workout session was 30 minutes long in this study, it is common for HIIT workouts to be much shorter than traditional exercise sessions.
This is because HIIT allows you to burn about the same amount of calories, but spend less time exercising.
Summary: HIIT may help you burn more calories than traditional exercise, or burn the same amount of calories in a shorter amount of time.
Your Metabolic Rate Is Higher for Hours After Exercise
One of the ways HIIT helps you burn calories actually comes after you are done exercising.
In the same study, HIIT was also found to shift the body's metabolism toward using fat for energy rather than carbs.
Another study showed that just two minutes of HIIT in the form of sprints increased metabolism over 24 hours as much as 30 minutes of running (14).
Summary: Due to the intensity of the workout, HIIT can elevate your metabolism for hours after exercise. This results in additional calories being burned even after you have finished exercising.
It Can Help You Lose Fat
Studies have shown that HIIT can help you lose fat.
One review looked at 13 experiments and 424 overweight and obese adults.
Additionally, one study found that people performing HIIT three times per week for 20 minutes per session lost 4.4 pounds or 2 kgs, of body fat in 12 weeks—without any dietary changes (16).
Perhaps more important was the 17 percent reduction in visceral fat, or the disease-promoting fat surrounding your internal organs.
Summary: High-intensity intervals can produce similar fat loss to traditional endurance exercise, even with a much smaller time commitment. They can also reduce unhealthy visceral fat.
You Might Gain Muscle Using HIIT
Additionally, it's important to note that increases in muscle mass are more likely to occur in individuals who were less active to begin with (24).
Some research in active individuals has failed to show higher muscle mass after HIIT programs (25).
Summary: If you are not very active, you may gain some muscle by starting HIIT but not as much as if you performed weight training.
HIIT Can Improve Oxygen Consumption
Oxygen consumption refers to your muscles' ability to use oxygen, and endurance training is typically used to improve your oxygen consumption.
Traditionally, this consists of long sessions of continuous running or cycling at a steady rate.
One study found that five weeks of HIIT workouts performed four days per week for 20 minutes each session improved oxygen consumption by 9 percent (6).
This was almost identical to the improvement in oxygen consumption in the other group in the study, who cycled continuously for 40 minutes per day, four days per week.
Another study found that eight weeks of exercising on the stationary bike using traditional exercise or HIIT increased oxygen consumption by about 25 percent (7).
Once again, the total time exercising was much different between groups: 120 minutes per week for the traditional exercise versus only 60 minutes per week of HIIT.
Summary: High-intensity interval training can improve oxygen consumption as much as traditional endurance training, even if you only exercise about half as long.
It Can Reduce Heart Rate and Blood Pressure
HIIT may have important health benefits, as well.
One study found that eight weeks of HIIT on a stationary bike decreased blood pressure as much as traditional continuous endurance training in adults with high blood pressure (7).
In this study, the endurance training group exercised four days per week for 30 minutes per day, but the HIIT group only exercised three times per week for 20 minutes per day.
Some researchers have found that HIIT may even reduce blood pressure more than the frequently recommended moderate-intensity exercise (29).
However, it appears that high-intensity exercise does not typically change blood pressure in normal-weight individuals with normal blood pressure (20).
Summary: HIIT can reduce blood pressure and heart rate, primarily in overweight or obese individuals with high blood pressure.
Blood Sugar Can Be Reduced by HIIT
Based on this information, it is possible that high-intensity exercise is particularly beneficial for those at risk for type 2 diabetes.
In fact, some experiments specifically in individuals with type 2 diabetes have demonstrated the effectiveness of HIIT for improving blood sugar (32).
Summary: High-intensity interval training may be especially beneficial for those needing to reduce blood sugar and insulin resistance. These improvements have been seen in both healthy and diabetic individuals.
Reposted with permission from our media associate Authority Nutrition.
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Fireworks Can Trigger Flashbacks<p>Hyperarousal, a core component of PTSD, occurs when a person is hyper-alert to any sign of threat – constantly on edge, easily startled and continuously screening the environment.</p><p>Imagine, for instance, stepping down the stairs in the dark after hearing a noise; you're worried an intruder might be downstairs. Then a totally unpredictable loud sound explodes right outside your window.</p><p>For people with PTSD, that sound – reminiscent of gunfire, a thunderstorm or a car crash – <a href="https://theconversation.com/veterans-refugees-and-victims-of-war-crimes-are-all-vulnerable-to-ptsd-130144" target="_blank">can cause</a> a panic attack or trigger flashbacks, a sensory experience that makes it seem as if the old trauma is happening here and now. Flashbacks can be so severe that combat veterans may suddenly drop to the ground, the same way they would when an explosion took place in combat. Later, the experience can trigger nightmares, insomnia or worsening of other PTSD symptoms.</p><p>Those of us who set off fireworks need to ask ourselves: Are those few minutes of fun worth the hours, days, or weeks of torment that will begin for some of our friends and neighbors – including many who put their lives on the line to protect us?</p>
Who Else Is Affected?<p>Millions of others, though not diagnosed with PTSD, may similarly be affected by fireworks. <a href="https://adaa.org/about-adaa/press-room/facts-statistics" target="_blank">One in five Americans</a> have an anxiety disorder, many with symptoms of hyperarousal. Also impacted are those with autism or developmental disabilities; they find it difficult to cope with the noise, or just the drastic change from life routines. Then there are people who have to work, holiday or not: nurses, physicians and first responders, who have to be up at 4 a.m. for a 30-hour shift.</p><h3>How to Reduce the Negative Impact</h3><p>There are ways to reduce how fireworks affect others:</p><ul><li>For those with PTSD, the unexpected nature of fireworks is probably the worst part. So at least make it as predictable as possible. Do it in designated areas during designated times. Don't explode one, for instance, two hours after the designated time window. And avoid setting them off <a href="https://www.theguardian.com/society/2018/jul/04/fireworks-ptsd-fourth-of-july-veterans-shooting-survivors" target="_blank">on the 3rd</a>. People are less prepared then.</li><li>If you're aware that a veteran or trauma survivor lives in the neighborhood, move the noise as far as possible from their home and give them prior warning. Consider putting a sign in your front yard noting the time you'll set the fireworks.</li><li>Remember, it doesn't have to be super loud to make it fun. Consider using <a href="https://thehill.com/opinion/energy-environment/504964-its-time-for-silent-fireworks" target="_blank">silent fireworks</a>. And you don't have to be the one who lights the fireworks. Simply enjoy watching while your city or township does it safely.</li></ul>
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By Jeff Berardelli
For the past year, some of the most up-to-date computer models from the world's top climate modeling groups have been "running hot" – projecting that global warming may be even more extreme than earlier thought. Data from some of the model runs has been confounding scientists because it challenges decades of consistent projections.
International Effort to Evaluate Climate Models<p>For the past 25 years the international community has been evaluating and comparing the world's most sophisticated climate models produced by various teams at universities, research centers, and government agencies. The effort is organized by the World Climate Research Programme under the United Nations World Meteorological Organization.</p><p>Climate models are complicated computer programs composed of millions of lines of code that calculate the physical properties and interactions between the main climate forces like the atmosphere, oceans, and solar input. But models also go a lot further, incorporating other systems like ice sheets, forests, and the biosphere, to name a few. The models are then used to simulate the real-world climate system and project how certain changes, like added pollution or land-use changes, will alter the climate.</p><p>Every few years there is a new comprehensive international evaluation called the Coupled Model Intercomparison Project (CMIP). In the sixth such effort, known as CMIP6 and now under way, experts are reviewing about 100 models.</p><p>Information gleaned from this effort will act as a scientific foundation for the U.N.'s Intergovernmental Panel on Climate Change (IPCC) next major assessment report, scheduled for release in 2021. The goal of the report – the sixth in 30 years – is to inform the international community about how much the climate has changed, and, importantly, how much change can be expected in coming decades.</p>
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In the above CarbonBrief interactive visualization, the bars offer a comparison in the range of sensitivity in the CMIP5 models (gray) and CMIP6 models (blue).
New and Encouraging Evidence Is Emerging<p>At first, scientists were uncertain whether the new model runs were on to something, so the international modeling community dug in to produce multiple studies. The results are not yet conclusive, but a gradual collective sigh of relief seems to be materializing.</p><p>"Evidence is emerging from multiple directions that the models which show the greatest warming in the CMIP6 ensemble are likely too warm," explains Dr. Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.</p><p>For example, <a href="https://www.earth-syst-dynam-discuss.net/esd-2020-23/" target="_blank">a study</a> released April 28 evaluated the past performance of the models making up the CMIP6 ensemble. The team assigned weights to each model based upon historical performance of their warming projections, weighing the poorer performing models less. By doing so, both the mean warming and the range of warming scenarios in the CMIP6 ensemble decreased, meaning the warmest models were the ones with weaker historical performance. This result supports a finding that a subset of the models are too warm.</p><p>That conclusion is supported by another new study evaluating one particular model – the Community Earth System Model (CESM2) – that showed greater warming. Using that model, the researchers simulated the climate in the early Eocene era, about 50 million years ago, when rainforests thrived in the Arctic and Antarctic. The CESM2 simulated a historical climate that seems way too warm compared with what is known about that era from geological data, indicating that the model is likely also too warm in its future projections.</p><p>Two other recent studies of the CMIP6 models being evaluated use clever analysis methods to <a href="https://www.google.com/url?q=https://www.earth-syst-dynam-discuss.net/esd-2019-86/&sa=D&ust=1589209938203000&usg=AFQjCNHYwFB-1KqndGfJ4sXdrrm9DpbLaQ" target="_blank">narrow the range</a> of future warming projections and also <a href="https://www.google.com/url?q=https://advances.sciencemag.org/content/6/12/eaaz9549&sa=D&ust=1589209938203000&usg=AFQjCNEhKY1YZ19qgjSZ_hJM14JmzqXOXw" target="_blank">reduce the projected warming</a> of the CMIP6 models by 10 to 15%.</p><p>Through the intensive research spurred by the CMIP6 climate-sensitivity curveball, scientists have been able to turn a confounding challenge into a confidence builder, providing even greater certainty than they had before in both the abilities of the climate science community and in the computer models used. Moreover, the experience has helped unearth uncertainties remaining in the modeling process.</p><p>Experts conclude much of this uncertainty probably lies in the complexity of clouds. "We have been looking as a community at why the models with greater warming are doing what they are doing – and it's tied to cloud feedbacks in the southern mid-latitudes mostly," explains Schmidt.</p><p>In fact, <a href="https://advances.sciencemag.org/content/6/26/eaba1981" target="_blank">a new study</a> addressing the increased sensitivity was published in Science Advances stating, "Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS [sensitivity] in CMIP6."</p>
Understanding the Complexity of Clouds<p>It's long been known in climate modeling circles that cloud processes and interactions are a potential weak link for climate modeling. That reality has been brought front and center by the urgent challenges posed during this CMIP6 evaluation period, but the current evaluation of models also provides an opportunity for discovery and improvement.</p><p>Cloud complexity comes from the reality that clouds have a multitude of sizes, altitudes, and textures. Some clouds cool Earth by providing shade, reflecting sunlight back into space. Others act like a blanket, trapping heat and warming the world.</p><p>Given that about <a href="https://www.nasa.gov/vision/earth/lookingatearth/icesat_light.html" target="_blank">70% of the globe</a> is covered by clouds at any given time, it's no surprise that they play an integral role in regulating the climate. The challenge is to figure out which types of clouds will increase, which will decrease, and what the net effect will be on cooling or warming as the climate changes.</p><p><a href="https://www.nature.com/articles/s41561-019-0310-1" target="_blank">One study</a> last year reached an alarming conclusion: Left unchecked, the release of CO2 into the atmosphere may lead to a tipping point where shallow low clouds disappear – leading to runaway, catastrophic warming of nearly 15 degrees F. While scientists see that outcome as only a remote possibility, it drives home the urgent need to better understand clouds.</p><p>"We have a saying at NOAA: It isn't rocket science – it's much, much harder than that," quips Dr. Chris Fairall, ATOMIC's lead investigator. "One of the major problems for modeling is there is not clean separation of scales." The photo below is one that Fairall took from the NOAA P-3 aircraft.</p>
Investigating the Secrets of Clouds<p>To address the urgent question about the dynamics and role of clouds in a warming world, NOAA and European partners launched their ongoing research effort unprecedented in scale. The U.S. contribution, ATOMIC – short for Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign – is an international science mission that was featured recently on "<a href="https://www.cbsnews.com/video/study-aims-to-examine-links-between-climate-change-and-clouds/" target="_blank">CBS This Morning: Saturday</a>."</p>
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