High Intensity Interval Training

A HIIT program done 3 times/week for 20 to 40 minutes could save considerable time72 and provide the same cardiovascular benefit and perhaps better weight-loss results without the compensatory food behaviors.

From: Textbook of Natural Medicine (Fifth Edition) , 2020

The Role of Physical Activity and Exercise in Managing Obesity and Achieving Weight Loss

Dr. Matthew D. Campbell PhD, ACSM CEP, BSc , Dr. Zoe H. Rutherford PhD, MSc, BSc , in Practical Guide to Obesity Medicine, 2018

High-Intensity Intermittent-Based Exercise

High-intensity intermittent exercise—which is often termed interval or HIIT training—involves performing repeated bouts of exercise at an intense effort interspersed by low-intensity exercise or periods of rest with varied recovery times. The exercise periods may range from 5   s to 8   min long with recovery periods varying in length and with total exercise duration lasting between 20 and 60   min. 4

The most obvious advantage of high-intensity exercise is the shorter time frame needed to expend an appropriate amount of energy. 17 This is an important consideration because when energy expenditure is matched, the reduction in weight is the same as when exercising for 300   min/week at a moderate intensity or 200   min/week at a vigorous intensity. 18 Interestingly, Ross and colleagues 18 observed differential changes in body fat distribution, following a high-intensity versus aerobic-based exercise training program. Following 24   weeks of a high-intensity exercise program, abdominal obesity was reduced by ∼4.6   cm (range −6.2 to 3.0   cm) compared with a reduction of ∼3.6   cm (range −5.1 to 2.2   cm) following an aerobic training program of equivalent length. Considering that a reduction in abdominal girth of ∼5   cm is associated with 9% lower mortality risk, 19 this finding is all the more clinically relevant. In addition, increasing exercise intensity may provide additional health benefits beyond increased energy expenditure. 18,20,21

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323485593000208

Volume 1

Keoni Teta ND , ... Ralph Esposito ND, LAc , in Textbook of Natural Medicine (Fifth Edition), 2020

Safety of Interval Exercise

HIIT, and intense weight training, can be used effectively and safely when combined with the appropriate use of heart rate (HR) monitoring, perceived exertion rate (PER), and the use of intervals: periods of exertion followed by rest. Studies show that this type of activity is manageable in several illness models, including chronic obstructive pulmonary disease, 91,92 post–coronary artery bypass patients, 93 congestive heart failure, 93 and heart transplantation patients. 94 This type of anaerobic stimulus more realistically mimics real-world challenge and allows for self-paced exercise that is safe, tolerable, and more beneficial for many heart and lung patients. 91–98 Cardiac patients also may have less risk with this type of activity because it has more favorable effects on ST-segment changes and heart rate variability (HRV). 96–98

Monitoring HR is useful for any health care provider prescribing exercise. It is important to understand that HR equations are merely estimates based on age; there is much variability. HR equations, in general, underestimate HRs in the very fit. The old HR equation of 220 − age is an inferior HR equation that underestimates HR in the old and overestimates in the young. 99 Newer equations allow for better predictive value. Based on current understanding, women and men should use separate equations for predicted HR percentages. For men, the MHR equation should be 208 − age (0.7). 99 For women, this equation should be 206 − age (0.88). 100 It is also useful to know the equation for translating percent of MHR to percent of oxygen uptake (VO2), and vice versa. That equation is %MHR = (0.64) %VO2 + 37.

Because multiple drugs and disease states can interfere with HR, exertion ratings used alone or combined with HR are a more useful clinical tool. In exercise research, a 16-point exertion scale called the Borg scale is used. It is a cumbersome tool to use and teach in clinical practice. A simple 1 to 10, with 10 being maximum exertion and 1 being at rest, is a far more useful tool clinically. It is easy to teach and implement. Traditional aerobic exercise scores between 6 and 8 on the 1 to 10 scale. HIIT will reach between 8 and 10 on the work phase and between 1 and 4 on the rest phase. In clinical practice, this is a useful aid in working with exercise intensity. Combining HR percent monitoring with PERs and heart rate recovery (HRR) allows for tight control of workout safety.

Two other useful clinical tools for health care practitioners are the "talk test" and HRR. Exertion and respiration are closely linked. The ability of a person to talk during exercise is a direct indication of whether they have crossed into the anaerobic zone. 101 For the unfit, this usually occurs around 55% of VO2 max, and for the very fit, it occurs around 85% VO2 max. This corresponds to 72% MHR and 91% MHR, respectively, leaving the average healthy exerciser right around 80% of MHR for the anaerobic threshold, at which point the ability to talk will be compromised. Correlating this "talk test" with an individual's HR allows practitioners to closely monitor exercise. HRR is a measure of how fast the heart recovers from exertion and is an indication of sympathetic and parasympathetic tone. A healthy heart should recover at least 25 beats/min or more within 1 minute after exertion. A heart that recovers 10 or fewer beats in 1 minute is a concern that should constitute a referral to a cardiologist. 102

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323430449000364

Physiology of Training Plan: Periodization

Zsolt Radák , in The Physiology of Physical Training, 2018

Acute Exercise at Maximal and Submaximal (>   85% of Maximum) Intensity Will Bring About the Following Physiological Responses

Generally, high intensity interval exercise, like exercise with Tabata protocol which consists of eight sets of exercise at the intensity of 170% of VO2max with 10-s rest (Tabata et al., 1996), results in enhanced mRNA expression, especially of those proteins that are involved in mitochondrial biogenesis and/or enhanced protein synthesis (AMPK, PGC-1a, SIRT1, NRF1, NRF2, TFAM, Akt, mTOR, HIF1a (Abe et al., 2015; Terada and Tabata, 2004 ) in skeletal muscle. Dr. Izumi Tabata, currently a professor at Ritsumaker University, Japan, was one of the first scientists to use and describe the effects of high intensity interval training.

Exercise with intensities over 130% of VO2max increases oxygen flow to muscle mitochondria by about 100-fold, and despite a large increase in blood delivery to contracting skeletal muscle, partial hypoxia takes place. This increase in metabolic demand cannot be covered by adequate energy supply, leading to increased levels of AMP, lactic acid, Pi, and other metabolites. For improved oxygen delivery, HIFa and VEGF induction would initiate the development of enhanced vascularization, especially with active recovery between exercise bouts (Wahl et al., 2014). It is important to note that active rest between exercise sets would further enhance the effects of this exercise regimen compared to passive resting periods, by enhancing lactate clearance and glycogen resynthesis (Choi et al., 1994). Similar findings have been reported when the effects of four sprints at maximal effort of 300, 3   ×   100, 400, and 2   ×   200   m were done by young athletes. The applied methods all resulted in increased elevation of lactic acid, but intermittent workouts (3   ×   100, 2   ×   200   m running) appeared to be superior when compared with continuous workouts of the same total distance by increasing the ability for energy production via the lactate system (Saraslanidis et al., 2009).

When the acute results of high intensity interval cycling and high-volume cycling of well-trained cyclists were studied for their hormonal profile, it turned out that high intensity work increased circulating growth hormone and cortisol levels compared to the high-volume exercise. High intensity-associated acidosis could be important in the elevation of these hormones, as the hormones elevate protein synthesis, protein turnover, repair, regulation of metabolic function, etc. Acute high intensity exercise results in elevated levels of circulating microRNA, which could be important as regulators of vascular and anabolic adaptive responses (Kilian et al., 2016).

High intensity resistance exercise results in elevated circulation of testosterone, suggesting an enhanced anabolic process. However, it must be mentioned that longer resting periods between sets, such as 3   min, is superior to short 1-min rest periods for the body to enjoy the long-term effects of elevated testosterone (Scudese et al., 2016). In addition, active rest with high acute intensity eccentric exercise readily cause micro damage if sarcomeres leading to muscle soreness (see Chapter 3 for a detailed description of muscle soreness).

Exercises that enhance cardiovascular function can beneficially affect motor learning, which could be important in the enhancement of sport performance. The results of a recent study indeed reveal that high intensity interval exercise improves the learning of ballistic tasks in trained and untrained limbs by reducing interference between trained and untrained hemispheres in the brain (Lauber et al., 2017). The authors also suggest that high intensity interval exercise could contributes to cognitive health, as it alters the event-related potential measured by electroencephalography (Kao et al., 2017). These results suggest that certain effects of exercise on brain function are dependent on the intensity of the exercise.

Interestingly, acute high intensity exercise could have a beneficial impact on patients with type 1 or type 2 diabetes. This kind of exercise results in increased production and accumulation of lactic acid, which is considered to preserve cognitive function and awareness of hypoglycemia (Rooijackers et al., 2017); moreover, the production of nitric oxide metabolites with this intensity of exercise could be important to the health-promoting effects of Tabata protocol.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780128151372000127

Impact of Lifestyle and Clinical Interventions on Mitochondrial Function in Obesity and Type 2 Diabetes

Brenna Osborne , ... Nigel Turner , in Mitochondria in Obesity and Type 2 Diabetes, 2019

2.3 High-Intensity Interval Training (HIIT)

More recently, many studies have looked at HIIT protocols in an effort to establish the best type of activity for improving cardiometabolic health, particularly in respect to patients with insulin resistance. 41 Because of its high intensity and shorter duration, HIIT exercise might be more appealing to patients who are time poor or struggle with the prescribed volume of lower intensity but longer duration workouts, 42 although the intensity required might not be appropriate for all patients. 43 One such study showed that rapid skeletal muscle remodeling similar to that seen in endurance training (see Fig. 1) can occur rapidly in response to HIIT training in young active men following a single acute HIIT protocol (4   ×   30   s bouts of all-out cycling). 44 mRNA levels of PGC1α increased (although no change was detected in total protein), combined with changes in signaling proteins in skeletal muscle such as AMPK subunits 1 and 2 and the p38 MAPK pathway immediately following exercise. 44 Little et al. later showed that a 6-week HIIT intervention in young healthy individuals also found significant mitochondrial biogenesis and skeletal muscle remodeling, with increases in the activity of CS and COX, as well as total protein content of CS, COX subunits II and IV, and the TFAM.

The abundance of nuclear PGC1α and the protein content of its proposed activator, the sirtuin SIRT1, was increased following HIIT training. 45 Followup studies by the same group in a more clinically relevant cohort of middle-age sedentary adults found that HIIT training for 2 weeks (6 sessions) was sufficient to induce skeletal muscle remodeling and mitochondrial biogenesis reported as increases in protein content of CS, COX, and PGC1α. In this study it correlated with improvements in insulin sensitivity measured by homeostatic model assessment (HOMA), a method of assessing insulin sensitivity in human subjects. 46 Six weeks of HIIT in overweight but healthy subjects also showed increases in mitochondrial content and oxidative phosphorylation capacity in skeletal muscle fibers, but no effect in adipose tissue explants. 47 Larsen et al. also showed that, in contrast to results seen with resistance and endurance exercise, 30, 48 HIIT intervention was unable to affect the oxidation of lipid substrates in mitochondria in skeletal muscle. 47 In spite of differences in the intensity and duration of the aerobic exercise, most studies agree that aerobic exercise as a lifestyle intervention in obese and type-2 diabetic subjects has beneficial effects on mitochondrial health.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B978012811752100016X

Lifestyle Interventions

Eva Prescott , in Chronic Coronary Artery Disease, 2018

Interval Training

In recent years the trend of increasing intensity has also been implemented through high-intensity interval training. Independent of energy expenditure, vigorous physical activity is more efficient than moderate activity in inducing cardiorespiratory fitness and metabolic fitness. 75,81,82 High-intensity interval training has been very popular among athletes for decades because it leads to more rapid improvement in cardiorespiratory fitness. A 2015 meta-analysis of studies comparing interval training with moderate continuous training in patients with coronary heart disease confirmed that interval training was more efficient in achieving cardiorespiratory fitness. 83 Some studies have indicated the superiority of a high-intensity interval training to moderate aerobic training for a variety of outcomes such as glycemic control, metabolic syndrome, and heart failure. 84,85 Not all studies confirm this though 86 and more larger-scale, multicenter studies with extended follow-up are needed to determine whether high-intensity interval training is superior to moderate training in leading to sustainable effects on cardiorespiratory fitness and, ultimately, improved outcomes.

Although there is some evidence pointing toward a more beneficial effect of exercise of greater intensity, this should be weighed against the greater risk of muscular and other injuries and, in selected patients with coronary heart disease, the potential risk of adverse cardiac events. For some individuals, e.g., patients with reduced left ventricular ejection fraction or patients who have residual reversible ischemia, the risk/benefit ratio for vigorous or hard exercise may be reversed.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323428804000182

Acute Medical Conditions: Cardiopulmonary Disease, Medical Frailty, and Renal Failure

Matthew N. Bartels , David Z. Prince , in Braddom's Physical Medicine and Rehabilitation (Sixth Edition), 2021

High-Intensity Interval Training

A new and exciting area of emerging research is the conditioning of cardiac patients with high-intensity interval training (HIIT). 124 , 156 Following appropriate screening and evaluation, patients are enrolled in a traditional cardiac rehabilitation program. Once they are familiar with the execution of exercise intervals, an accurate setup of exercise machines trials of HIIT can be introduced. Patients are instructed to exercise at high intensity (>85% of Vo 2max) for short or ultra-short intervals followed by low-intensity or rest intervals. 126 It is recommended to start HIIT training on seated machines to reduce likelihood of falls on standing machines due to loss of balance, distraction during interval initiation or termination, and dizziness from blood pressure fluctuations. Meticulous blood pressure and telemetry monitoring should take place until the practitioner is confident they have established an individualized baseline response for each patient. Additional considerations are the potential for exercise-induced hypoglycemia—an expected and physiologically beneficial outcome. Symptomatic hypoglycemia can be quickly treated with any source of oral glucose. It is important to reassure cardiac patients that hypoglycemic symptoms are not the onset of cardiac ischemia to reduce negative associations with exercise. HIIT has been shown to provide significant conditioning benefits in the cardiac rehabilitation population with medically supervised selection of candidates. 88

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323625395000278

BEAST Fitness Training

Greg LeMond , Mark Hom M.D. , in The Science of Fitness, 2015

Before we enter into specific training categories, it should be explained what they have in common (varied in proportion and emphasis, depending on the fitness goals):

1.

High-intensity interval training (HIIT) in order to trigger mitochondrial biogenesis. With more mitochondria, the athlete will have more energy on tap. With this power the athlete will go faster and endure longer.

2.

Frequent exercise to avoid mitochondrial atrophy. With mitochondrial energy, it is use it or lose it. To maintain fitness, we must exercise at least every other day. If we stop exercising for a week or more, we can lose massive amounts of fitness that will take many weeks or months to regain.

3.

Base mileage to promote endurance and mitochondrial fat burning. When beginning a new sport or starting a new season, a foundation of low to moderate levels of exercise is especially important to prime the body in preparation for the more intense training to follow.

4.

Strength building with resistance exercises to build muscle mass. This will raise metabolism, increase power, change body composition (more muscle and less fat), improve outward appearance, and lessen or prevent age-related muscle atrophy.

5.

Avoidance of overuse, overtraining, and injury. Too much exercise of the wrong type can be counterproductive. Any serious or nagging injury can be a major impediment in attaining fitness.

6.

A balanced diet including: fuel for cellular energy, hydration for optimal performance, and nutrients for the recovery and rebuilding of our cells and muscles.

7.

The motivation to stay with a sport or exercise program for years (or a lifetime). Exercise should always be a pleasure and should never become a chore.

8.

The goal of ever improving fitness. Although an Olympic athlete knows what it is like to reach the highest levels in a sport, most of us fall well short of reaching our true athletic potential. SciFit training advice will try to raise the athletes' bar, so they can expect more and get more out of their training.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780128010235000119

Exercise-Based Cardiovascular Therapeutics: From Cellular to Molecular Mechanisms

Siyi Fu , ... Junjie Xiao , in Lifestyle in Heart Health and Disease, 2018

Exercise Treatment

The Oxford Dictionary defines exercise as "activity requiring physical effort, carried out to sustain or improve health and fitness." As a planned, structured, and repetitive physical activity, exercise can be divided as aerobic and anaerobic one such as swimming, jogging, high-intensity interval training (HIIT), cycling, yoga, or even tai chi [10,11]. Endurance proper exercise, short time for high-intensity anaerobic exercise, or long time for low-intensity aerobic exercise have increasingly been found to contribute to health and are considerable ways for physical rehabilitation. There is a vast literature on the beneficial effects of physical exercise on all-cause and CVD-related mortality [12]. Here, we focus on the effects of physical exercise on CVD, and the underlying mechanism will also be discussed.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780128112793000070

Molecular and Cellular Regulation of Adaptation to Exercise

David A. Hood , ... Heather Carter , in Progress in Molecular Biology and Translational Science, 2015

9 Alternative Exercise Programs: High-Intensity Interval Training

Endurance training has been known for many years to stimulate mitochondrial biogenesis, an effect which contributes to an increased aerobic endurance capacity in trained subjects. 11,60 However, endurance training requires a notable time commitment, in terms of both the frequency and duration of exercise sessions, in order to elicit positive results. In order to circumvent these challenges, alternative training programs to induce similar outcomes have been explored.

In addition to exercise duration and frequency, exercise intensity is a central determinant of the cellular and biochemical alterations which occur in response to a training program. As different muscle fiber types are recruited in a hierarchical manner determined by the intensity of exercise employed, it would appear that an intensity of exercise sufficient enough to recruit the greatest number of fiber types might be the most useful in facilitating whole muscle adaptations. Dudley et al. provided one of the first pieces of evidence, suggesting that exercise intensity is directly related to the magnitude with which skeletal muscle mitochondrial enzyme content is augmented. 61 This work also put forward the idea that a variety of high-intensity interval training (HIIT) programs may be capable of yielding increases in skeletal muscle oxidative capacity similar to that of a continuous endurance training program. This has since been corroborated by evidence in human skeletal muscle, as both endurance and interval training approaches provide similar increases in the expression of oxidative genes 62 and mitochondrial content markers. 63,64 The increase in mitochondrial proteins is likely due to the increase in the phosphorylation of p38, AMPK, and p53, which can be evoked by a single bout of HIIT, 65,66 and can mediate the translocation of PGC-1α protein to the nucleus. This translocation has been associated with increases in the mRNA and protein levels of a variety of mitochondrial markers, such as citrate synthase and cytochrome c oxidase subunit IV during the recovery phase. 67–69 These changes appear to be a product of the accruing effects of repeated mitochondrial mRNA "bursts" which follow each individual training bout. 70

In addition to promoting mitochondrial biogenesis, it has been suggested that interval training programs can foster the remodeling of the mitochondrial network. An increase in the protein expression of the mitochondrial fusion protein Mfn1 as well as the fission proteins Fis1 and Drp1 as a result of a HIIT program has been documented. 70 This may have implications for mitochondrial function, as skeletal muscle mitochondria isolated from individuals who have undergone a HIIT program display an increase in the maximal ADP-stimulated respiration rate and respiratory control ratio. 71

In sum, when contrasting these two approaches to increasing skeletal muscle mitochondrial content at this point in time, the HIIT routine appears to afford a notable reduction in the time invested in exercise, perhaps providing an attractive substitute for continuous training regimens. Whether this exercise regime is suitable for all populations remains under debate.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/S1877117315001398

Exercise and Physical Activity for Older Adults

Dale Avers , in Guccione's Geriatric Physical Therapy, 2020

Interval and High-Intensity Interval Training

Interval aerobic training programs are the most efficient to improve cardiopulmonary and endurance performances and general health, even in older adults. 71 Interval training is suitable for healthy adults and those with cardiorespiratory disease, vascular disease, and diabetes. 72,73 The advantages of an interval program over constant-intensity programs are the superior improvements in several cardiovascular outcomes, as well as in fitness and performance, 72,74,75 even in those with cardiopulmonary and vascular disease. Box 8.6 lists the benefits of interval and HIIT training. 76 Interval training may be more effective in untrained individuals than sustained aerobic activity of similar duration in improving cardiopulmonary fitness and blood glucose concentrations but less effective in improving resting heart rate, body composition, and total cholesterol–to–high-density lipoprotein (HDL) ratio. 14

HITT is a form of interval training exercise in which individuals alternate periods of short, intense, nonoxidative exercise at maximum effort with less intense recovery periods. HIIT allows equal or improved outcomes for markedly less time investment and is associated with greater adherence, with results apparent in as little as 2 weeks. 77 Examples of HITT protocols are listed in Table 8.3. Although few studies have examined HIIT on older adults, the Generation 100 study, 19 using HITT principles, demonstrated 60% adherence to the prescribed intensity (≥   15 on the Borg scale) at two times/week over 1 year without strict supervision, although women had a lower adherence rate with high-intensity exercise than did men. HITT is known to be safe for healthy older adults as well as those with diabetes, stable angina, and heart failure, and after myocardial infarct, cardiac stenting, and coronary artery grafting. 73,78

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323609128000087