If you had to pick the better runner — a sprinter or a marathoner — the answer would depend on the type of race. In a 200-meter race, the sprinter will have an edge over the marathoner, but if it calls for, say, 18 miles, the marathoner will outrun the sprinter.
That’s how you should think about high-intensity interval training (HIIT) and low-intensity steady-state (LISS) cardio. One type of workout isn’t necessarily better than the other, but one might be better suited for you, depending on your fitness goals.
What exactly is the difference between HIIT and LISS cardio? HIIT involves alternating between short bursts of intense effort with periods of rest or active recovery. There are many ways to do HIIT, but some of the most popular work-to-rest ratios are 30 seconds of work and 30 seconds of rest, 45 seconds of work and 15 seconds of rest, or four minutes of alternating between 20 seconds of work and 10 seconds of rest (also known as a Tabata).
LISS cardio is low-intensity exercise, such as walking, jogging and cycling, at a relatively easy pace.
“If you’re looking to do a marathon, mud run or endurance-based activity, put some energy into LISS. But if you’re looking to be more explosive, athletic or build muscle, HIIT workouts are best suited to help you do that,” said Rafique “Flex” Cabral, a NASM-certified personal trainer and Isopure athlete.
To help you decide which type of exercise is best for you, here are different scenarios where HIIT or LISS could be more beneficial.
If you’re new to exercise and just want to get moving
Whether you’re a gym newbie or are getting back into working out after a hiatus, LISS is a good way to ease into exercise. Because you’re working at a low intensity, you may be able to work out for a longer period of time and exercise more consistently. HIIT workouts — although shorter — require more effort from your muscles and can be stressful on the joints.
“Older adults experience great results with LISS cardio as it improves their bone density and musculoskeletal health, in turn promoting healthier aging. These benefits also allow for a cost-effective means in promoting positive improvements in the ability to carry out activities of daily living,” said Lisa Reed, MS, CSCS, a performance coach and owner of Lisa Reed Fitness, LLC.
If you want to lose weight and rev up your metabolism
Doing any type of LISS cardio will burn calories, helping you achieve the calorie deficit you need to lose weight. But turning up the intensity of your workout is ultimately going to help you burn more calories, giving HIIT an edge.
“LISS is great for improving endurance activities and cardiovascular work capacity, and aids in recovery and weight loss. But if you’re trying to gain muscle, which helps burn fat, LISS may not be the best thing to add into your routine frequently,” explained Cabral.
HIIT helps you build and maintain moderate amounts of lean muscle mass. It also produces an afterburn effect called excess post-exercise oxygen consumption (EPOC), said Cabral. EPOC is the amount of calories you burn long after your workout is over, and HIIT is the most effective workout for stimulating EPOC, according to the American Council on Exercise.
The after-burn effect of EPOC can last anywhere from 12 to 48 hours, according to the ACE. “[With HIIT] you will produce an after-burn effect with 25 percent more calories burned post-workout compared to going for a run or walk,” said Reed, and your metabolism can be boosted by up to 10 percent for three days after a HIIT workout. “Maintaining a routine that involves HIIT training three to four times a week will help compound that post-workout effect on your metabolism,” Cabral explained.
If you want to boost your athletic performance
“Incorporating resistance training into your HIIT workouts can help build and maintain muscle, particularly your type II fast-twitch muscle fibers, which are necessary for athletic movement,” Cabral said.
You have two different muscle fibers: type I (slow-twitch muscle fibers) and type II (fast-twitch muscle fibers). Your type I muscle fibers are built for endurance activities, such as running a marathon and biking long distances, while type II muscle fibers are made for quick, explosive movements. Think: sprints, jumps and heavy lifts.
So if you have your sights set on improving the height of your jumps or increasing the load of your deadlifts, then HIIT is the way to go.
That said, HIIT is extremely taxing on the body, so you shouldn’t do it every day. Doing HIIT two to three times a week is more than enough, and you should aim to recover at least 48 hours between your workouts, per the ACE.
LISS cardio is a great way to add variety to your workouts and prevent over training. Mixing in some low-intensity work, like walking or doing a leisurely bike ride or swim, allows you to get some movement as your muscles repair.
If you don’t have a lot of time to exercise
What’s great about HIIT is that you don’t have to work nearly as long as LISS cardio to get an effective workout, and you can customize your workout with different exercises and pieces of equipment.
“HIIT workouts are an excellent way to increase your workout intensity in a short amount of time — 20 minutes or less. You can also keep things interesting by switching up the sequence or swapping out different exercises from strength to high-intensity movement,” Reed said.
In fact, a small study in the Journal of Strength and Conditioning Research compared the calorie expenditure of nine healthy men doing 30 minutes of strength training, endurance cycling, endurance running on a treadmill, and HIIT training. The results showed that HIIT burned more calories than the other three workouts, suggesting that you can burn more calories with a 30-minute HIIT workout than doing steady-state cardio in the same amount of time.
That’s not to say that you can’t get a great workout with LISS cardio, too. LISS cardio can help you get more movement into your day while reaping the benefits of exercise. But HIIT can be helpful if you want to get more out of your workout in less time.
How can you make your HIIT and LISS workouts more challenging?
To level up your LISS cardio workouts, Cabral recommended adding different types of activities into your routine, like running, biking, swimming and rowing.
When it comes to HIIT, Cabral said experimenting with different variables can spice things up. Some ideas: “Decreasing the rest time while increasing the work time or increasing both the work and rest periods, adding more rounds, and increasing the weights for strength-based movements,” Cabral said. “HIIT workouts
How many times a week should you do HIIT and LISS training?
Reed recommended incorporating both LISS cardio and HIIT into your workout routine to reap their health benefits. “My philosophy has always been that every little bit counts. Walk for at least 30 minutes, five times a week and perform a HIIT workout two to three times per week [for] 10 to 20 minutes per workout,” Reed suggested.
Another great way to add both LISS cardio and HIIT into your routine: Perform a 15-minute HIIT workout followed by 30 minutes of LISS cardio. “You will be burning more calories from fat when you follow HIIT with any LISS activity,” Reed said.
Cabral recommended following a 2:1 HIIT to LISS ratio for building muscle, and if your goal is more endurance-based, reverse that ratio.
For beginners, Cabral suggested working out two to three times a week, working your way up to three to five times per week.
“Your fitness goals will determine the balance of what you need to be able to look and perform the way you want. Everyone is different, so finding that balance might take a little trial and error, which is ultimately worth it when you find what works best for you,” Cabral said.
Ancient Jordanian town destroyed by a meteor blast may have inspired Biblical stories, scientists say – CBC.ca
A thriving town in the Jordan River valley was utterly annihilated by the explosion of a meteor 3,600 years ago, which produced a flash and shock wave that scorched and shattered buildings, animals and people.
That’s the scenario painted by a large collaboration of archaeologists, earth and space scientists who have been studying the remains of the Bronze Age town at a site called Tall el-Hammam in Jordan, not far from the Dead Sea.
Before its destruction, Tall el-Hammam was a bustling town of perhaps 8,000 people, with mud-brick buildings and a four-story palace. There is evidence that the site of the town had been occupied for several thousand years.
Archaeologists have been excavating the ruins of the town for more than 15 years, revealing a rich history during its long occupation that included ruins from fires, warfare and earthquakes.
Their findings were published this month in the journal Scientific Reports.
The ‘destruction layer’
But their excavations also revealed destruction that didn’t have any ordinary explanation: a one-and-a-half-metre-thick layer of debris the team dubbed the “destruction layer,” encompassing the whole settlement, and dated to 1650 BC. This layer showed signs of an incredibly violent event.
It included melted pottery and bricks, soot, melted plaster and metal, that only could have resulted from temperatures approaching 2,000 C. It also contained ruins of flattened buildings, including the town’s palace and four metre-thick outer wall.
“The city was built with millions of mud bricks, in the walls, the ramparts, the buildings,” space physicist Malcolm LeCompte, who was part of the research team, told Quirks & Quarks host Bob McDonald. “Much of the mud brick was just disintegrated and blown away off the upper stories of these structures into the next valley.”
Most gruesomely, the debris also contained the remains of humans and animals that had been burned and torn apart.
“The human remains and bones were abundant. There’s very few total skeletal remains. Those that do remain are pretty disarticulated — just shattered,” said LeCompte. “It’s pretty horrifying, actually.”
The extreme temperatures and the widespread and violent destruction began to point the research team to a culprit. But microscopic examination of the debris also helped build the case. They found sand grains with unique cracks and fractures within them called “shocked quartz,” which are often found in the debris from super-high velocity impacts, like those generated by a meteor strike.
This led them to conclude that the best fit for what they were seeing was an “air burst” by meteor likely composed of rock and ice. The object, perhaps 50 metres across, would have hit the Earth’s atmosphere above the town travelling at perhaps 60,000 km/h. At that speed the atmosphere would have behaved as if it was almost solid, causing the meteor to explode violently.
“The evidence we have suggests that it was something like … a megaton-yield event in terms of its equivalent in atomic or nuclear bombs.” said LeCompte.
On the ground, the flash of heat from the explosion would have caused hair and textiles to burst into flame, and melted metal and brick. Moments later, a shock wave would have hit, causing winds that researchers estimate reached speeds of up to 1,200 km/h — knocking structures in the town flat and killing every living thing in the town.
“The shock wave would have come and just torn them apart,” said LeCompte.
It will happen again, LeCompte warns
The researchers point out that there are modern precedents for an event like this. In 1908 a similar-sized object is thought to have exploded in the atmosphere over Siberia, in what is known as the Tunguska event. It flattened 2,000 square kilometres of forest, and started a huge forest fire.
In 2013 a roughly 200-metre meteor exploded over Chelyabinsk in Russia, shattering windows and causing more than 1,000 injuries.
So far the team has found some material they think could be from the meteor, including tiny samples of rare metals often found in meteorites, but need to do more work to confirm their origin. LeCompte points out that excavation in the area can be difficult, particularly as much of the local landscape is currently occupied by Syrian refugees.
One intriguing, if speculative, possibility that the researchers have suggested is that the destruction of Tall el-Hammam might be the inspiration behind Biblical legends like the destruction of Sodom — in what is described as a “rain” of “fire and brimstone” — or the destruction of the walls of Jericho.
But LeCompte says those that look at Tall el-Hammam as a historical curiosity are missing the point. Instead, he said, they should look at it as a warning.
“The significance to its past pales in what it foretells for the future, because this is going to happen again,” he said. The Tunguska event shows that the Earth can still be struck by destructive objects from space, and if something similar were to happen over a city or populated region, the devastation would be enormous.
“It just took it out in an instant, so that’s a serious warning of what could happen — what will happen — in the future.”
Written by Jim Lebans. Produced by Mark Crawley.
Archaeologists find oldest known human footprints in the Americas – HeritageDaily
Archaeologists conducting research in the White Sands National Park in New Mexico has identified the oldest known human footprints in the Americas.
The findings provide the earliest unequivocal evidence of human activity in the Americas from over 23,000 years ago, a period during the height of the last glacial cycle, known as the Last Glacial Maximum.
Archaeologists have debated for decades when the first people arrived in the Americas, but Vance T. Holliday from the UArizona School of Anthropology and Department of Geosciences said: “Few archaeologists see reliable evidence for sites older than about 16,000 years. Some think the arrival was later, no more than 13,000 years ago by makers of artefacts called Clovis points. The White Sands tracks provide a much earlier date. There are multiple layers of well-dated human tracks in streambeds where water flowed into an ancient lake. This was 10,000 years before Clovis people.”
The team used radiocarbon dating of seed layers above and below the footprints to determine their age, which showed human presence at the site lasting two millennia, and the oldest track dating back 23,000 years.
Kathleen Springer from the U.S. Geological Survey said: “Our dates on the seeds are tightly clustered and maintain stratigraphic order above and below multiple footprint horizons – this was a remarkable outcome”.
An analysis on the size of the human footprints suggests that they were mainly teenagers and younger children, whilst other tracks indicate that they were left by mammoths, giant ground sloths, dire wolves, and birds.
“It is an important site because all of the trackways we’ve found there show an interaction of humans in the landscape alongside extinct animals, like mammoths and giant sloths.” said Sally Reynolds of Bournemouth University. “We can see the co-existence between humans and animals on the site as a whole, and by being able to accurately date these footprints, we’re building a greater picture of the landscape.”
Header Image Credit : David Bustos – White Sands National Park
Bird reports rose during lockdowns | Cornell Chronicle – Cornell Chronicle
Around 80% of bird species examined in a new study were reported in greater numbers in human-altered habitats during pandemic lockdowns, according to new research based on data from the eBird program at the Cornell Lab of Ornithology.
In the paper, “Reduced Human Activity During COVID-19 Alters Avian Land Use Across North America,” published Sept. 22 in Science Advances, researchers compared online eBird observations from the United States and Canada from before and during the pandemic. They focused on areas within about 100 km of urban areas, major roads, and airports.
Vast amounts of data from a likewise vast geographic area were vital for this study. The researchers used more than 4 million eBird observations of 82 bird species from across Canada and the U.S.
“A lot of species we really care about became more abundant in human landscapes during the pandemic,” said study senior author Nicola Koper of the University of Manitoba, which led the research. “I was blown away by how many species were affected by decreased traffic and activity during lockdowns.”
Reports of bald eagles increased in cities with the strongest lockdowns. Ruby-throated hummingbirds were three times more likely to be reported within a kilometer of airports than before the pandemic. Barn swallows, a threatened species in Canada, were reported more often within a kilometer of roads than before the pandemic.
A few species decreased their use of human-altered habitat during the pandemic. Red-tailed hawk reports decreased near roads, perhaps because there was less roadkill when traffic declined. But far more species had increased counts in these human-dominated landscapes.
The authors filtered pandemic and pre-pandemic eBird reports so that the final data sets had the same characteristics, such as location, number of lists, and level of birdwatcher effort.
“We also needed to be aware of the detectability issue,” said co-author Alison Johnston, assistant director of the Center for Avian Population Studies and Ecological Data in the Lab of Ornithology. “Were species being reported in higher numbers because people could finally hear the birds without all the traffic noise, or was there a real ecological change in the numbers of birds present?”
The study tested whether better detectability might be a factor in the larger bird numbers reported. If it was, the scientists expected that to be more noticeable for smaller birds, which are harder to detect beneath traffic noise. However, effects were noticed across many species, from hawks to hummingbirds, suggesting that the increased numbers were not only caused by increased detectability in the quieter environments.
“Having so many people in North America and around the world paying attention to nature has been crucial to understanding how wildlife react to our presence,” says lead author Michael Schrimpf, a postdoctoral fellow at the University of Manitoba. “Studies such as this one rely on volunteer birdwatchers, so if you enjoy watching wildlife, there are many projects out there, like eBird and iNaturalist, that can use your help.”
The study was funded by Natural Sciences and Engineering Research Council of Canada with in-kind support provided by Environment and Climate Change Canada and the Cornell Lab of Ornithology.
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