HIGH INTENSITY INTERVAL TRAINING CREATES MANY PHYSIOLOGICAL AND ANATOMICAL IMPROVEMENTS

High Intensity Interval Training (HIIT) →

  • ↑ muscular, cardiorespiratory fitness + ↓ obesity
  • ↑ skeletal muscle oxidative capacity and endurance
  • ↑metabolic control during aerobic-based exercise  
  • ↑ skeletal muscle health
  • ↑ satellite cells; skeletal muscle‐specific stem cells
  • satellite cells → ↑ skeletal muscle repair + ↑ regeneration   
  • ↑cardiovascular adaptation   
  • ↑ capillarisation of skeletal muscle
  • ↑ myoglobin concentration
  • ↑ oxidative capacity of type II skeletal muscle fiber        
  • voluntary wheel running ↑ gene expression changes in brain
  • exercise ↑ + supports brain function
  • soccer was found very HIIT beneficial for good health 
  • exercise ↑ brain-derived neurotrophic factor, a molecule increases neuronal survival, enhances learning, protects against cognitive decline

Research revealed that “recreational football (soccer) and High Intensity Interval Training (HIIT) elicited improvements in all muscular and cardiorespiratory fitness measures.

“In contrast, the control group, which performed only physical education classes, increased body mass, BMI, and fat mass.

Therefore, additional activities such as recreational football or HIIT might counter the prevalence of overweight and obesity in children. [Exercise training in overweight and obese children: Recreational football and high‐intensity interval training provide similar benefits to physical fitness N. Cvetković, E. Stojanović, N. Stojiljković, D. Nikolić, A. T. Scanlan, Z. Milanović, 06 July 2018, Scandinavian Journal of Medicine & Science in Sports]

Likewise the “Football is Medicine‐model suggests that integrating sports science, sport training physiology, sports medicine, sports psychology and sports sociology results are beneficial (Fig1)2.

“Football (soccer) for Health have all been published in the Scandinavian Journal of Medicine and Science in Sports and they tell a unique story about the development of the research and the gradually increasing focus on football as therapy. The first was published in 2010 focusing on “Football as prevention”,12-14 the second in 2014 expanded on the work on “Football as prevention and treatment”,15-19 and the present special issue published in 2018 is entitled “Football is Medicine” and emphasizes the comprehensive results and the huge implications of using the world’s most popular sport, with an estimated 500 million regular participants,2 as a therapy. [The “Football is Medicine” platform—scientific evidence, large‐scale implementation of evidence‐based concepts and future perspectives by P. Krustrup et al 19 June 2018 Scandinavian Journal of Medicine & Science in Sports]

“Regular endurance training was demonstrated that improved performance during tasks that rely mainly on aerobic energy metabolism, in large part by increasing the body’s ability to transport and use oxygen and altering substrate metabolism by working skeletal muscle.

“However, many studies have shown that a sufficient volume of high-intensity interval training (HIT), performed for at least 6 weeks, increases peak oxygen uptake (V˙O2peak) and the maximal activity of mitochondrial enzymes in skeletal muscle (16,21).

“Recent evidence suggests that a number of metabolic adaptations usually associated with traditional high-volume endurance training can be induced faster than previously thought with a surprisingly small volume of HIT.

“The present article briefly summarizes work from our laboratory (5-8,11) and others (18,21) that sheds new light on the potency of HIT to induce rapid changes in exercise capacity and skeletal muscle energy metabolism

“High-intensity interval training (HIT) is a potent time-efficient strategy to induce numerous metabolic adaptations usually associated with traditional endurance training. As little as six sessions of HIT over 2 week or a total of only approximately 15 min of very intense exercise (~600 kJ), can increase skeletal muscle oxidative capacity and endurance performance and alter metabolic control during aerobic-based exercise. [Metabolic Adaptations to Short-term High-Intensity Interval Training: A Little Pain for a Lot of Gain? By Gibala, Martin J.1; McGee, Sean L.2 Exercise and Sport Sciences Reviews: April 2008 – Volume 36 – Issue 2 – p 58-63]

“Satellite cells are indispensable for skeletal muscle repair and regeneration and are associated with muscle growth in humans.

“Aerobic exercise training results in improved skeletal muscle health also translating to an increase in satellite cell pool activation. We postulate that aerobic exercise improves satellite cell function in skeletal muscle.

“Skeletal muscle‐specific stem cells are termed ‘satellite cells’ and are indispensable for skeletal muscle repair and regeneration.

“In addition, recent studies suggest that satellite cells also may respond to endurance exercise.

“Because satellite cells are imperative to skeletal muscle regeneration, heightened activation of the satellite cell pool after aerobic exercise training may render skeletal muscle repair more efficient after injury.

“The potential of aerobic exercise to improve the capacity of skeletal muscle to repair and remodel via improved satellite cell function is markedly improved. [The Impact of Aerobic Exercise on the Muscle Stem Cell Response, Joanisse, Sophie1; Snijders, Tim2; Nederveen, Joshua P.3; Parise, Gianni3,4 Exercise and Sport Sciences Reviews: July 2018 – Volume 46 – Issue 3 – p 180–187]

“High-intensity aerobic interval training results in a greater beneficial adaptation of the heart compared with that observed after low-to-moderate exercise intensity.

“This is supported by recent epidemiological, experimental, and clinical studies. Cellular and molecular mechanisms of myocardial adaptation to exercise training are discussed in this review. [High-Intensity Interval Training to Maximize Cardiac Benefits of Exercise Training? By Wisløff, Ulrik 1,2; Ellingsen, Øyvind 1,2; Kemi, Ole J.3 Exercise and Sport Sciences Reviews: July 2009 – Volume 37 – Issue 3 – p 139-146]

“The maximal oxygen uptake (V-dotO(2max)) is considered an important physiological determinant of middle- and long-distance running performance.

“Training intensities of 40-50% V-dotO(2max) can increase V-dotO(2max) substantially in untrained individuals. The minimum training intensity that elicits the enhancement of V-dotO(2max) is highly dependent on the initial V-dotO(2max).

“Well trained distance runners probably need to train at relative high percentages of V-dotO(2max) to elicit further increments. Some authors have suggested that training at 70-80% V-dotO(2max) is optimal. Many studies have investigated the maximum amount of time runners can maintain 95-100% V-dotO(2max) with the assertion that this intensity is optimal in enhancing V-dotO(2max).

“Presently, there have been no well controlled training studies to support this premise. Myocardial morphological changes that increase maximal stroke volume, increased capillarisation of skeletal muscle, increased myoglobin concentration, and increased oxidative capacity of type II skeletal muscle fibres are adaptations associated with the enhancement of V-dotO(2max).

“The strength of stimuli that elicit adaptation is exercise intensity dependent up to V-dotO(2max), indicating that training at or near V-dotO(2max) may be the most effective intensity to enhance V-dotO(2max) in well trained distance runners. Lower training intensities may induce similar adaptation because the physiological stress can be imposed for longer periods.

“This is probably only true for moderately trained runners, however, because all cardiorespiratory adaptations elicited by submaximal training have probably already been elicited in distance runners competing at a relatively high level.

“Well trained distance runners have been reported to reach a plateau in V-dotO(2max) enhancement; however, many studies have demonstrated that the V-dotO(2max) of well-trained runners can be enhanced when training protocols known to elicit 95-100% V-dotO(2max) are included in their training programmes.

“This supports the premise that high-intensity training may be effective or even necessary for well-trained distance runners to enhance V-dotO(2max). However, the efficacy of optimised protocols for enhancing V-dotO(2max) needs to be established with well controlled studies in which they are compared with protocols involving other training intensities typically used by distance runners to enhance V-dotO(2max). [Is there an optimal training intensity for enhancing the maximal oxygen uptake of distance runners?: empirical research findings, current opinions, physiological rationale and practical recommendations by Adrian Wayne Midgley, Lars Mcnaughton Michael Wilkinson, Sports Medicine 36(2):117-32 · February 2006, Source: PubMed]

“Physical activity, in the form of voluntary wheel running, induces gene expression changes in the brain. Animals that exercise show an increase in brain-derived neurotrophic factor, a molecule that increases neuronal survival, enhances learning, and protects against cognitive decline.

“Microarray analysis of gene expression provides further support that exercise enhances and supports brain function. [Exercise Enhances and Protects Brain Function by Cotman, Carl W.; Engesser-Cesar, Christie, Exercise and Sport Sciences Reviews: April 2002 – Volume 30 – Issue 2 – p 75-79 2002]

“Exercise training at a variety of intensities increases maximal oxygen uptake (VO2max), the strongest predictor of cardiovascular and all-cause mortality.

“Research performed a systematic review, meta-regression and meta-analysis of available literature to determine if a dose-response relationship exists between exercise intensity and training-induced increases in VO2max in young healthy adults.

“These data suggest that exercise training intensity has no effect on the magnitude of training-induced increases in maximal oxygen uptake in young healthy human participants, but similar adaptations can be achieved in low training doses at higher exercise intensities than higher training doses of lower intensity (endurance training).

“Collectively, the results of the analyses carried out in the current work suggest that training at any intensity above ~60% of VO2max is likely to improve maximal oxygen uptake in healthy adults.

“Our observations suggest that high-intensity, sub- and near-maximal exercise (~80–92.5% VO2max) may be the ideal exercise intensity range for eliciting improvements in VO2max as both training volume, and exercise intensity are low compared to moderate and supramaximal intensity training, respectively.

“While our data supports claims regarding the efficiency and potency of high-intensity training, they also highlight future directions for research examining the impact of exercise intensity on improvements in VO2max and the mechanisms by which high-intensity exercise achieves its potency. [SCRIBBANS TD, VECSEY S, HANKINSON PB, FOSTER WS, GURD BJ. The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis. International Journal of Exercise Science. 2016;9(2):230-247]

“Some individuals show little or no increase in maximal oxygen consumption (V˙O2max) in response to training programs consistent with public health guidelines. However, results from studies using more intense programs challenge the concept that some humans have limited trainability. We explore the implications of these divergent observations on the biology of trainability and propose a new set of twin studies to explore them. [Concepts About V˙O2max and Trainability Are Context Dependent by Joyner, Michael J.1; Lundby, Carsten2, Exercise and Sport Sciences Reviews: July 2018 – Volume 46 – Issue 3 – p 138–143]

“Increases in maximal oxygen uptake (VO2max) are widely reported in response to completion of high intensity interval training (HIIT), yet the mechanism explaining this result is poorly understood. This study examined changes in VO2max and cardiac output (CO) in response to 10 sessions of low-volume HIIT.

“Data demonstrated significant improvements in VO2max (2.71±0.63 L/min to 2.86±0.63 L/min, P<0.001) and COmax (20.0±3.1 L/min to 21.7±3.2 L/min, P=0.04) via HIIT that were not exhibited in CON.

“Maximal Stroke Volume was increased in HIIT (P=0.04) although there was no change in maximal HR (P=0.57). The increase in VO2max seen in response to ten sessions of HIIT is due to improvements in oxygen delivery.  [J Sports Med Phys Fitness. 2018 Jan-Feb;58(1-2):164-171. doi: 10.23736/S0022-4707.16.06606-8. Epub 2016 Jul 8., Increased cardiac output and maximal oxygen uptake in response to ten sessions of high intensity interval training, by Astorino TA1, Edmunds RM2, Clark A2, King L2, Gallant RM2, Namm S2, Fischer A2, Wood KA2]

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