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Gas exchange and lactate threshold are valid indicators of moderate-intensity aerobic exercise, rat study finds

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Gas exchange and lactate threshold are valid indicators of moderate-intensity aerobic exercise, rat study finds
Credit: Andrea Piacquadio from Pexels

Researchers at University of Tsukuba identified a previously unconfirmed gas exchange threshold in rats and demonstrated that this threshold, together with the lactate threshold, serves as an indicator of moderate-intensity exercise to determine the effectiveness of training in enhancing aerobic performance.

The study is published in Medicine & Science in Sports & Exercise. This achievement is fundamental for basic research on exercise. It will be useful for researchers in the field of health and fitness promotion as it provides a useful moderate-intensity index for rats.

During incremental aerobic exercise, there are thresholds where blood lactate levels begin to rise, and CO2 production increases rapidly relative to O2 uptake. The former threshold is termed the lactate threshold (LT), and the latter, the gas exchange threshold (GET). In humans, these thresholds are moderate-intensity exercise indices, with LT and GET at 45%–74% of the maximal oxygen uptake (VO2max). Training at or above these thresholds improves aerobic performance.

In contrast, in rats, LT has been identified, but GET is not known yet. Furthermore, it is unclear whether the rat GET and LT can be useful indicators of exercise intensity similar to the thresholds in humans.

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The researchers previously established a rat model for identifying the LT during running exercise. This study aimed to simultaneously identify LT and GET by integrating this LT model with the standard human GET identification method, known as the V-slope method.

Subsequently, the relationships among the identified GET, LT, and VO2max, as well as the changes in these thresholds following aerobic training below or above the LT, were examined. The results showed that GET and LT in rats occurred synchronously at intensities ranging from 41.0% to 65.5% VO2max, and that the maximal (VO2max) and submaximal (GET, LT) aerobic capacities were enhanced only in rats that trained at intensities above the LT.

These results suggest that the GET and LT in rats are valid indices of moderate-intensity exercise in training prescription to enhance aerobic performance as in humans. The findings of this study are expected to serve as a catalyst for further research in the field of rat studies focused on exercise intensity, ultimately contributing to the advancement of human exercise prescription strategies. In particular, the noninvasive and easily identifiable nature of the GET from the exhaled gas suggests a wide range of potential applications.

More information:
Koshiro Inoue et al, Setting Treadmill Intensity for Rat Aerobic Training Using Lactate and Gas Exchange Thresholds, Medicine & Science in Sports & Exercise (2024). DOI: 10.1249/MSS.0000000000003562

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Move Over, Aches and Pains: 11 Best Yoga Stretches For Easing Tightness, Tension, and Stiffness

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Move Over, Aches and Pains: 11 Best Yoga Stretches For Easing Tightness, Tension, and Stiffness

I’m getting old.

Well, I’m not, not really. But as I creep further into my late twenties, the aches and pains are starting to feel worthy of someone beyond my years. They’ve even become a running dinner table topic amongst my friends. Each of us seems to have acquired a niggle, a dodgy joint or a pulled muscle we can compare over pasta, right alongside our new obsessions with homeware and the unexpected thrill of a good vacuum cleaner.

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Fitness Experts Share Their Number-1 Aerobic Exercise Tip for Longevity

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Fitness Experts Share Their Number-1 Aerobic Exercise Tip for Longevity

As strength-training after the age of 50 has been steadily rising in popularity in recent years, love for traditional cardiovascular or aerobic exercise has been on the decline. Still, making this form of exercise a regular part of your routine is just as important to maintaining your vitality as you age—and following the below aerobic exercise tips for 50 plus can help you get the most out of every session.

According to the Cleveland Clinic, aerobic exercise is any activity that you do continuously that increases your heart rate, such as walking, jogging, cycling, swimming, or dancing. “Regular aerobic activity helps mitigate risks like cardiovascular disease, insulin resistance, and bone density loss by improving heart health, managing body composition, enhancing insulin sensitivity, and reducing systemic inflammation,” said Mark Kovacs, Ph.D., C.S.C.S., a human performance scientist and longevity expert.

These benefits become especially important during and after menopause, when your risk of developing osteoporosis and heart disease go up. “Estrogen helps keep blood vessels flexible and cholesterol levels in check,” explained Brooke Bussard, M.D., a certified personal trainer and owner of Brooke’s Balanced Blueprint, a lifestyle medicine health coaching practice in Baltimore, MD. “When estrogen drops, regular aerobic exercise helps pick up the slack by keeping your circulatory system healthy.”

In fact, adults at 50 with ideal cardiovascular health are expected to live an additional 36.2 years, on average, while adults with poor cardiovascular health were only expected to live an additional 27.3 years, according to a 2023 study in the journal Circulation.

Meet the experts: Mark Kovacs, Ph.D., C.S.C.S., is a human performance scientist and longevity expert. Brooke Bussard, M.D., is a certified personal trainer and owner of Brooke’s Balanced Blueprint, a lifestyle medicine health coaching practice in Baltimore, MD.

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The best part? You don’t need to run marathons or swim hundreds of laps to get the benefits. You don’t need to be an experienced exerciser either. So whether you’re just getting started or looking for ways to mix up your exercise regimen, these expert-backed tips will help you feel better and healthier for years to come.

Just be sure to check with your doctor before starting a new fitness routine, especially if you have high blood pressure or any heart problems, including heart disease. And if you feel off while exercising, get medical help right away.

How to get the most out of aerobic exercise at 50 plus

1. Aim for 150 minutes a week—but break it into small chunks.

    The CDC recommends 150 minutes of moderate-intensity aerobic activity per week. But “this is a minimum recommendation,” said Kovacs: People who worked out two to four times above the moderate physical activity recommendations (about 300 to 599 minutes each week) saw the most benefit in a 2022 study published in Circulation.

    Still, something is better than nothing. “The best plan is the one you can stick with,” said Dr. Bussard, who recommends walking for about 30 minutes five times a week. If three 10-minute dance breaks a day works better for you, that’s cool, too. It all adds up—and workouts of less than 10 minutes still count toward recommended weekly activity goals, according to the CDC.

    2. Use the talk test to measure your intensity.

    Not sure if you’re working hard enough for your activity to count as a workout? Try talking. “For heart-healthy aerobic exercise, you should be slightly breathless but still able to hold a conversation,” said Dr. Bussard.

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    You can also determine intensity using a scale from 1 to 10. “Moderate intensity (like a brisk walk or steady cycling) typically corresponds to a five or six out of 10 on the effort scale,” said Kovacs, “while vigorous aerobic exercise (fast walking uphill or jogging) should feel like a seven to eight out of 10, where talking becomes difficult.”

    3. Don’t count out low-impact activities.

    Cycling, elliptical training, swimming, or walking on an incline are all joint-friendly ways to raise your heart rate. “These options reduce joint stress, which is critical as cartilage, tendons, and ligaments may become less resilient with age,” said Kovacs.

    But “low-impact doesn’t mean low-intensity,” said Dr. Bussard. “You can absolutely work up a sweat and challenge your heart and lungs without pounding your joints.” Just pay attention to the effort you’re exerting in the moment and aim to hit that five out of 10.

    4. Work in short, quick bursts.

    “Adding short bursts of faster-paced intervals to your aerobic routine boosts the benefits,” said Dr. Bussard, as long as you’re cleared by your doctor to work harder. Recent research in the journal Lipids in Health and Disease shows that high-intensity interval training (HIIT) can improve insulin sensitivity, blood pressure, and overall fitness—“all areas that can decline during menopause,” she added.

    This kind of training is considered vigorous activity, so you don’t need as much of it: Just two HIIT sessions per week (with a total training time of 20 minutes per workout) improved working memory and lower-body muscle function more than moderate-intensity continuous cycling, and boosted cardiorespiratory fitness just as much, according to a 2023 study published in The Journals of Gerontology.

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    5. Mix up your workouts.

    Boredom is the enemy of consistency. Try different types of cardio—like hiking, aqua aerobics, Zumba, or even pickleball. “Varying modalities challenges different muscle groups, reduces overuse injury risk, and improves neuromuscular coordination,” said Kovacs. “It also helps sustain motivation and supports functional aging by preparing the body for a wider range of physical challenges.”

    6. Let your body recover.

    As you age, your body may take longer to bounce back. “Recovery between workouts often takes longer due to a combination of physiological changes,” said Kovacs. “These include slower muscle protein synthesis, reduced hormone levels (like estrogen and growth hormone), and less efficient mitochondrial function—all of which contribute to slower tissue repair and reduced energy availability.”

    Make sure to allow 48 to 72 hours of muscle recovery between higher-intensity sessions, and prioritize adequate sleep, sufficient nutrition, and active recovery, like gentle walking or mobility work. And listen to your body; if you feel wiped out for days, scale back and allow more rest between sessions.

    7. Take the time to warm up.

    Older muscles and joints need more prep. “As estrogen drops, tendons and ligaments get stiffer, so warming up is more important than ever to prevent injuries,” said Dr. Bussard. “A good warm-up should move your joints through a full range of motion and activate your major muscles.” Try inchworms, bodyweight squats with overhead reaches, and side-to-side lunges—just five to 10 minutes can prime your body for exercise.

    8. Pair cardio with strength-training.

    Women over 50 benefit most when they combine cardio and strength-training, as both play essential but distinct roles in healthy aging. “Aerobic exercise keeps your heart healthy, but you need strength training to keep your muscles and bones strong,” said Dr. Bussard. Putting them together is the real key. “Combined, they form the foundation of long-term healthspan and mobility,” said Kovacs.

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Runners share their wellness journeys on KSAT Connect ahead of the San Antonio Marathon

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Runners share their wellness journeys on KSAT Connect ahead of the San Antonio Marathon

Full and half-marathons will take place Dec. 7

Runners, joggers and walkers shared their health and fitness experiences on KSAT Connect in anticipation of the San Antonio Marathon weekend. (KSAT Connect)

SAN ANTONIO – Runners, joggers and walkers shared their health and fitness experiences on KSAT Connect in anticipation of the San Antonio Marathon this weekend.

Ahead of the inaugural SATX Marathon on Dec. 7, KSAT invites you to share photos, short videos and personal stories about why you are running, who you’re running for and what the race means to them.

>> What to know about the San Antonio Marathon: Street closures, routes, expo

Check out these photos and videos uploaded to KSAT Connect:

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Raul

Running the SA Rock and Roll Marathon, 2yrs. With my dog Cannoli. We ran 26.2 miles. This year, I will be running solo, 26.2 miles. With my dog Cannoli, running the last 3 miles. Crosssing the finish line together.

Jam1230

–My running journey started many years ago with a prayer for discipline to exercise consistently and from my first run to my current exercise activity I thank God for the ability to do so. As many of my immediate family members battle diabetes, I strive to exercise diligently keeping them in mind and believing for them to remain courageous in their fight. Endurance running has shown me enhanced health, physical growth and increased faith. I’m so glad to participate in the first San Antonio Half Marathon this weekend. Good luck and God bless all participants.

Julian

How to participate:

  • Open the KSAT News app, KSAT Weather app, or visit the KSAT Connect web page. We recommend using the KSAT News app for regular access to KSAT Connect!
  • If you’re on the KSAT News app, click KSAT Connect in the navigation bar at the bottom of your screen. If you’re in the KSAT Weather Authority app, open the navigation bar at the top left of your screen and click KSAT Connect.

  • Sign in or sign up for a FREE KSAT Insider (member) account by clicking the orange button with the text “Log in to Upload a Pin.”

  • Once you’re signed in, you’ll click the orange button that now reads “Upload a Pin.”

  • Click the blue button at the top to choose the photo or video you’d like to share.

  • Select “Outdoors” as the channel and “Activities” as the category.

  • Tell us about your photo or video by including a description.

  • Click the orange button at the bottom to upload.

KSAT may select submissions to feature on air and online. KSAT encourages entrants to respect privacy and only post media they own or have permission to share.

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Share your training, your triumphs and the reasons you run — KSAT wants to tell your story.


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