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Cardiorespiratory and aerobic demands of squat exercise – Scientific Reports

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Cardiorespiratory and aerobic demands of squat exercise – Scientific Reports

The main questions of our study are to examine the maximal V̇O2 achieved during five sets of squat exercises (10 reps per set, 5 sets, 3 min rest interval, 65% of 1RM) in relation to predetermined V̇O2max and how these values differ according to participants’ training status. Our study showed that the highest V̇O2 was observed during the 5th set of squat exercises, almost reaching 100% of the participants’ predetermined V̇O2max. When the highest V̇O2 values were presented according to training status, participants with higher strength experienced an increase in V̇O2 during squat exercise up to 108% of their V̇O2max, while the highest V̇O2 of participants with lower strength was 93.7% of their V̇O2max, measured immediately after the final set. When the highest V̇O2 during five sets were averaged, participants reached over 90% of their V̇O2max. Regardless of participants’ training status, oxygen demand during squat exercise was extremely high.

An increase in V̇O2 during resistance exercises has been previously reported. However, there are substantial differences in the amount of V̇O2 between our study and previous studies9,19. Previous studies reported V̇O2 during squat exercises ranging from approximately 16 to 31.3 ml/kg/min depending on the length of the rest intervals9,19. In the present study, we observed values above 40 ml/kg/min, and in some participants, V̇O2 increased above 50 ml/ kg/min, exceeding their pre-determined V̇O2max. A significantly greater V̇O2 observed among our participants could be due to training status and the specific exercise protocol. The 1RM among our participants was 141.4 ± 31.3 kg, whereas the 1RM reported by Ratamess et al.9 was 127.9 ± 31.1 kg. Furthermore, Ratamess et al.9 employed higher intensity resistance exercise, set at 75% of 1RM, whereas our study employed a lower intensity, 65% of 1RM. Given that all participants in our study successfully completed 10 reps of squats until the fifth set whereas participants from Ratamess et al.9 did not, the exercise in the current study elicited a higher demand for aerobic metabolism. Another rationale for the relatively higher V̇O2 during our squat exercise could be due to different squat techniques. In the present study, all participants were instructed to perform a full squat with a full range of motion. In contrast, other studies either utilized only half squats or did not specify the depth of the squat. Performing full squatting is likely to elicit a higher oxygen demand.

Interestingly, the levels of V̇O2 relative to V̇O2max and the highest heart rate relative to maximal heart rate clearly showed that multiple sets of resistance exercise could be considered as vigorous- or high-intensity cardiovascular activity20,21,22. When viewed from an intensity perspective, squat exercise can be classified as a form of vigorous- or high-intensity activity22. However, since vigorous- or high-intensity aerobic activity is defined as an activity sustained for a prolonged period (e.g., ≥ 10 min)22, squat exercise does not meet this criterion given the rest interval periods and therefore may not be described as such. Furthermore, our findings suggest that aerobic demand of resistance exercise is much greater when individuals could exercise at a higher intensity without sacrificing the volume, represented as number of repetitions. Among the participants with high strength, V̇O2 exceeded their pre-determined V̇O2 max at the 4th set of squat exercise, while participants with low strength reached up to 91.69% of their V̇O2max at the 4th set. One noteworthy implication of our study is that we examined the fluctuations in cardiorespiratory responses and RPE throughout the progression of squatting repetitions and sets. This stands in contrast to merely assessing the average and peak V̇O2 observed during one bout (i.e., session) of squatting.

During rest intervals, we observed higher CO2 production than VO2 consumption, whereas the opposite was observed during the squat exercise periods. Typically, individuals only breathe once at each descending and ascending motion within a repetition during squat exercise, resulting in this distinctive breathing pattern that may cause a difference between pulmonary and cellular metabolic demands. During squatting exercises, participants may not be able to exhale sufficient amounts of CO2 produced as a result of bicarbonate buffering process. Breathing is modulated by central and peripheral chemoreceptors, which may respond to CO2 and H+23,24. Although elevations in CO2 and H+ during squat exercise are the primary precursors to an increase in breathing, breathing is limited to the exercise rhythm during squatting, which may cause hypercapnic acidosis24,25. When breathing was no longer limited to the exercise rhythm during rest intervals, participants hyperventilated and exhaled CO2. The increase in V̇CO2 in relation to V̇O2 was significant. While we did not measure the partial pressure of arterial CO2, our results indicated that participants experienced hypercapnia during the five sets of squat exercise. This was demonstrated by the ventilatory efficiency (Supplemental Fig. 2), which showed a continuous increase with successive sets. Diverse breathing techniques employed during squatting may yield varying V̇O2 and V̇CO2 responses.

It is unclear whether training proficiency and subsequent muscular strength are determinants of cardiorespiratory fitness26,27,28,29. Highly trained individuals are accustomed to a higher training intensity and frequency than relatively less-trained individuals, leading to greater neuromuscular output and adaptation30. As such, highly trained individuals can perform a greater volume (load, repetitions, intensity) of squat exercises, which may result in a higher level of V̇O2 than those with low strength during resistance exercise. Interestingly, we observed that the high strength group showed a higher level of V̇O2 (relative; normalized to body weight) at the same relative intensity compared with the low strength group. These results suggest that aerobic demand of resistance exercise may be more evident among individuals with certain levels of resistance training status. In addition, the predetermined V̇O2max level was lower in the high strength group compared to the low strength group, although this difference was not statistically significant. Furthermore, it is crucial to note that all study participants performed the squat exercise at 65% of their individual 1RM. This indicated that the squat load was obviously higher in the high strength group compared to the load used by the low strength group. Therefore, the high strength group may exhibit higher V̇O2 responses compared to the low strength group due to relatively lower aerobic efficiency and/or the absolute training load during exercise in the high strength group. Individuals, who are not accustomed to resistance exercise, may not have the same cardiorespiratory response as observed in our study.

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The effort inherent to the execution of squatting exercises at 65% of 1RM, as performed in our study, is submaximal. This relative intensity corresponds to a margin of repetitions that is less than maximal exertion, influencing the V̇O2 observed. Previous research11,31 has established a relationship between the number of repetitions and selected percentages of one repetition maximum in both trained and untrained men. These studies11,31 indicate that the effort required at 65% of 1RM is substantial but not maximal, which aligns with our findings of significant oxygen demand during the exercise intervals. Our study further highlights that the substantial oxygen demand observed during the squatting exercise is influenced by both the training status of the participants and the submaximal nature of the effort. The high strength group demonstrated a higher V̇O2 relative to their V̇O2max compared to the low strength group. This suggests that individuals with higher strength capacity may be able to sustain higher aerobic demands during resistance exercises, even at submaximal intensities.

This study has several limitations. First, the findings of this study are specific to the squat exercise protocol used and cannot be generalized to other resistance exercise protocols, such as chest presses or arm curls. Different volumes (i.e., intensity, repetition, and training load) of squat exercises may result in different outcomes11. Second, nutritional and hydration intakes, which may be potential confounders, were not controlled for in this study. These factors may have impacted the association between squatting and cardiorespiratory outcomes. Lastly, our findings may not be generalizable to wider populations, given that we examined young, healthy, well-trained, male participants only.

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Mere minutes of daily vigorous exercise can cut your risk of 8 diseases | CNN

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Mere minutes of daily vigorous exercise can cut your risk of 8 diseases | CNN

Move more. Sit less. For many years, that’s been accepted guidance for people wanting to get healthier.

Now that message is getting refined, with a growing body of research suggesting that certain types of movements may be more beneficial than others when it comes to health benefits.

The intensity of your exercise may matter as well. A new study published in the European Heart Journal found that a small amount of vigorous activity may be linked to lower risk of eight different chronic diseases.

The findings raise questions about why intensity matters and how people can incorporate more intense exercise routines into everyday life. To better understand the study’s implications, I spoke with CNN wellness expert Dr. Leana Wen, an emergency physician and clinical associate professor at George Washington University. She previously served as Baltimore’s health commissioner.

Before beginning any new exercise program, consult your doctor. Stop immediately if you experience pain.

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CNN: What did this study examine about exercise and its relationship to chronic disease?

Dr. Leana Wen: This investigation looked at how the intensity of physical activity is related to the risk of developing a range of chronic diseases. Researchers analyzed data from two very large groups in the UK Biobank, which is a long-term health study in the United Kingdom that tracks medical and lifestyle information from hundreds of thousands of participants. One group included about 96,000 people who wore wrist activity trackers that objectively measured their movement, and the other included more than 375,000 people who self-reported their activity.

The researchers followed participants over an average of about nine years and examined the development of eight conditions: major cardiovascular events, atrial fibrillation, type 2 diabetes, immune-related inflammatory diseases, fatty liver disease, chronic respiratory disease, chronic kidney disease and dementia, as well as overall mortality.

The key finding was that the proportion of activity done at vigorous intensity mattered. People who had more than about 4% of their total activity classified as vigorous had substantially lower risks of developing these conditions compared with people who had no vigorous activity at all. The numbers were stunning, with the participants having the following results:


  • 63% lower risk of dementia,

  • 60% lower risk of type 2 diabetes,

  • 48% lower risk of fatty liver disease,

  • 44% lower risk of chronic respiratory disease,

  • 41% lower risk of chronic kidney disease,

  • 39% lower risk of immune-mediated inflammatory diseases,

  • 31% lower risk of major cardiovascular events,

  • 29% lower risk of atrial fibrillation, and

  • 46% lower risk of death from any cause.

These results are amazing. Imagine if someone invented a medication that could reduce the risks of all these diseases at once — it would be very popular! Crucially, even people who exercised a lot still benefited if the proportion of time they spent doing vigorous physical activity was increased. Conversely, people who were relatively inactive also benefited from adding just a little bit of higher-intensity exercise to their daily routines.

CNN: What counts as “vigorous” physical activity?

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Wen: Vigorous activity is generally defined as exercise that substantially raises your heart rate and breathing. A simple way to gauge it is the “talk test.” If you can speak comfortably in full sentences while exercising, you are likely in the low to moderate range. If you are so out of breath that you can only say a few words at a time, that is vigorous.

Running, cycling, lap swimming or climbing stairs quickly could count. But this also depends on people’s baseline fitness. For some individuals, taking longer strides with walking can be vigorous exercise. Others who are already fairly fit would need to do more. It’s also important to remember that vigorous activity doesn’t have to be in the context of a structured exercise plan. Short bursts of effort in daily life, such as rushing to catch a bus or carrying heavy groceries upstairs, can also qualify if they raise your heart rate and make you breathless.

CNN: Why might higher intensity exercise provide additional health benefits?

Wen: Higher intensity activity places greater demands on the body in a shorter period. This type of movement can improve cardiovascular fitness, increase insulin sensitivity and support metabolic health more efficiently than lower-intensity activity alone. Some studies have also linked vigorous activity with cognitive benefits.

Greater intensity may have distinct benefits across different organ systems. The researchers found that some conditions, such as immune-mediated inflammatory diseases, appeared to be more strongly linked to the intensity of activity than to the total amount. On the other hand, type 2 diabetes and kidney disease were influenced by both how much activity people did and how intense it was. Why this is the case is not yet known, but intensity appears to have a significant impact across diseases affecting multiple organs.

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CNN: How much vigorous activity do people need?

Wen: The threshold for people seeing a benefit appears to be relatively low. The researchers found that once people reached more than about 4% of their total activity as vigorous, their risk of developing chronic diseases dropped substantially.

To put that into practical terms, we are not talking about professional athletes dedicating their lives to hours of high-intensity training. Everyday people may see benefits from just doing a few minutes of vigorous effort daily.

CNN: How can people realistically incorporate vigorous activity into their daily routines?

Wen: One helpful way to think practically is that vigorous activity does not have to happen all at once. It can be accumulated in short bursts throughout the day.

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People can take the stairs instead of the elevator and do so at a faster pace than usual. When they are heading to work, they can add some speed walking. They can park farther away when grocery shopping and walk briskly while carrying groceries.

Structured exercise also can incorporate intervals where people alternate between moderate and more intense effort. If you’re swimming laps, you can warm up at a more leisurely pace, then do a few laps at a faster pace, then again at a leisurely pace and repeat. This suggestion applies to any other aerobic exercise: Aim for multiple intervals of at least 30 seconds to a minute each where your body is working hard enough that you feel noticeably out of breath.

CNN: What about someone who is older or has mobility issues?

Wen: Not everyone can or should engage in high-intensity activity in the same way. Vigorous activity is relative to that person’s baseline. For someone who is not used to exercise, even a short period of slightly faster walking or standing up repeatedly from a chair could be considered high intensity. And not everyone may be able to walk. In that case, some exercises from the chair can have aerobic benefits.

Individuals who have specific medical conditions should consult with their primary care clinicians before embarking on a new exercise routine. People with mobility issues also may benefit from working with a physical therapist who can help to tailor exercises appropriate to their specific situation.

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CNN: What is the key takeaway for people trying to improve their health?

Wen: To me, the main takeaway from this study is that it’s not only how much total exercise you get but also how hard you push yourself that matters. And you don’t have to have a lot of high-intensity exercise: Adding just a little has substantial health benefits across a wide range of chronic health conditions.

At the same time, exercise needs be practical. People should look for opportunities to safely increase intensity in ways that fit their daily lives. The most effective approach to physical activity is a balanced one: Exercise regularly, incorporate more challenging activities when you can and build habits that are sustainable over time.

Get inspired by a weekly roundup on living well, made simple. Sign up for CNN’s Life, But Better newsletter for information and tools designed to improve your well-being.

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‘Not what the fitness industry is trying to sell you’: this is the one simple move everyone really needs to be doing, according to an exercise scientist

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‘Not what the fitness industry is trying to sell you’: this is the one simple move everyone really needs to be doing, according to an exercise scientist

Ask any exercise scientist what they would prescribe to someone serious about staying strong into their 50s and beyond, and the answer is rarely what you’d hope for — and certainly not what the fitness industry is currently trying to sell you.

It isn’t long sessions on one of the best under-desk treadmills or a stationary bike like the Peloton, nor the kind of machine-based exercises that isolate muscles without ever teaching them to work together.

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Ellie Kildunne built her powerful body by keeping things simple – focusing on these fundamentals

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Ellie Kildunne built her powerful body by keeping things simple – focusing on these fundamentals

Despite being named World Rugby’s Women’s 15s Player of the Year, England rugby star Ellie Kildunne admitted on an episode of Just As Well that the ‘gym was never easy’. In order for her to feel her best, she sticks to a no-nonsense approach to training and nutrition that focuses on the fundamentals: consistent exercise and eating enough.

‘If I haven’t put the work in, if I’ve skipped reps, if I haven’t eaten the right amount for the game, I would feel anxious,’ she says in her cover interview for Women’s Health UK. ‘But I’ve never put myself in that position because I want to be the best.’

What does being the best mean to her? ‘I want to become world player of the year twice. That’s my focus. Anything else that happens is by the by.’

On her episode of Just As Well last year, she said strength training now makes her ‘feel powerful’, while she ‘hates running’ – but a lot of her training involves speed, agility and endurance practice for her time on the pitch. That mix of conditioning and strength means she has built a strong, fast and resilient body.

Speaking of her physical transformation, she admits her personal body image hasn’t always been positive: ‘Body image is such a mental challenge,’ she tells Women’s Health UK. ‘My body is what made me World Player of the Year… I’ve got to remind myself of that.’ Visibility helps too: ‘We’re in that transition phase… social media is starting to lean more towards athletic women… I see people that look like me now.’ Now, Ellie says when she sees a muscular person, she thinks, ‘Respect. Because I know exactly what goes into that.’

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Headshot of Bridie Wilkins

As Women’s Health UK’s fitness director and a qualified Pilates and yoga instructor, Bridie Wilkins has been passionately reporting on exercise, health and nutrition since the start of her decade-long career in journalism.

After earning a first-class degree in journalism and NCTJ accreditation, she secured her first role at Look Magazine, where she launched the magazine’s health and fitness column, Look Fit, before going on to become Health and Fitness writer at HELLO!

Since, she has written for Stylist, Glamour, Cosmopolitan, Marie Claire, Elle, The Metro, Runner’s World and Red. Today, she oversees all fitness content across Women’s Health online and in print, spearheading leading cross-platform franchises, such as ‘Fit At Any Age’, which showcases the women proving that age is no barrier to exercise.

She has also represented the brand on BBC Radio London, plus various podcasts and Substacks – all with the aim to encourage more women to exercise and show them how. Outside of work, find her trying the latest Pilates studio, testing her VO2 max for fun (TY, Oura), or posting workouts on Instagram.   

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