WHAT IS HIGH INTENSITY INTERVAL TRAINING?

High intensity interval training (HIIT) is a variation of interval training. Generally Interval training consists of increasing intensity workouts (low to high) that are interspersed by periods of rest. [1]The high-intensity bursts of the workout are perceived to be periods of anaerobic exercise or leading to that physical state [2]. Contrastingly the rest or recovery periods are of significantly lower intensity [3]. By increasing the output of work/effort in the high intensity intervals the overall bulk of training decreases [4].

WHY AND HOW IS HIIT SUGGESTED FOR COPD PATIENTS?

Physical training is known to be beneficial to COPD patients and is therefore implemented in the ‘comprehensive management of the disease’.[5]Patients with this condition commonly suffer from dyspnea symptoms which can easily lead to a cycle of deconditioning [6]. This occurs when the physical activeness of a chronically ill patient lessens, affecting their ability to perform exercise and daily activities.

In establishing rehabilitative exercise routines for COPD patients limiting factors that were considered when evaluating the response to training compared to healthy individuals, in order to establish optimal patient-specific exercise plans, included([7][8][9]):

• Abnormalities in gas exchange
• Dynamic lung hyperinflation
• Limiting expiratory flow
• Energy supply to peripheral and respiratory muscles being insufficient

Due to the above within minutes of starting the routine patients are faced with breathlessness and exhaustion.

HIIT has proven to work around these limitations as maximal loads on both oxygen-transporting organs and peripheral muscles [10] (that are aerobic processes) without much engagement of anaerobic processes[11]that lead to lactic acid accumulation. Therefore slowing the time of exhaustion by slowing the usage of anaerobic fuel stores.

HIIT may be particularly suitable for patients with advanced COPD who cannot sustain exercise intensities for a time period long enough to experience a physiological training [12]effect by allowing dyspnea sensations to be tolerated for longer, lactic acidosis puts pressure on the ventilation system and in HIIT only a small increase in arterial lactate is observed [13]. Thus reducing the acid stimulus to breathe and in turn the stress on the ventilation system ([14]).

Although further studies will be required, in order to appropriately set time/interval training work load in patients differing in COPD severity, an established matter is the frequency of the exercise which ideally should be undertaken 3-4 times weekly. [15]

If we take exercising on an ergometer following a HIIT workout as an example to explore how we should set up training measures for people with severe COPD. We must consider using short intensity intervals, as these patients find them more tolerable [16]). By setting a work to rest interval ratio 30 seconds to 30 seconds we can, as a starting point, exercise them at an intensity 80% equivalent to their maximal work load. Overtime increasing their work load by 5-10% when they perceive their dyspnea as moderate. Then we should find that the COPD patient has more control over his/her breathing [17]. In addition if, in the 30-second breaks when patients focus solely on breathing techniques, taught by physiotherapists patients adopt pursed lip breathing then enhanced improvements in tidal volume as well as decrease end-expiratory volume should be evident [18]

SUPPORTING STUDIES

In order to fully understand and appreciate the benefits of HIIT on COPD, researchers use Continuous exercise as a normal to compare to.

Rognmo et al set up a randomised controlled trial (RCT), lasting 10 weeks to evaluate VO2 peak. In which patients were places into HIIT or MCT (moderate continuous exercise) groups [19].

• HIIT group performed 4 sets of 4 minutes high-intensity exercise intervals at 80-90% their VO_2peak (maximum oxygen uptake) paired with low-intensity exercise intervals at 50%–60% VO_2peak for a total time of 33 min.
• MCT group exercised for 41 continuous min at 50%–60% of their VO_2peak.
• Total amount of training done was equal for the 2 groups using percentage of VO_2peak to calculate this and ensure a fair measure.¹⁹

The graph represents the results from the RCT and it is evident that although the VO2 peak for both groups increased significantly the HIIT’s VO2 peak improvement of 17.9% was significantly greater than the improvement of 7.9% found for the MCT group. Taking into account that none of the patients in either exercise groups suffered from cardiac events during the programme, in cardiac patients HIIT proved greater aerobic capacity adaptations compared to MCT without any increase in medical risk.

A COPD patient undergoing any form of exercise activity will experience symptoms of Dyspnea, Leg fatigue and lactic acid build up in the blood stream. Prescribed exercise plans should aim to reduce the impact of these symptoms, below is a graph comparing the effects of the two training methods (HIIT and MCT).

In all 3 graphs, 10 minutes into the continuous exercise routine the maximal level of Dyspnea, leg fatigue and Lactic acid concentration was reached meaning the patients could no longer continue the work out. However all 3 symptoms increased during the first 10 minutes of the interval training and continued to rise steadily (at a slower rate to the initial 10 mins) and only after around 30 minutes did Leg fatigue and Dyspnea experienced reach its maximum level while as maximal lactic acid effects were not reached as concentration stabilised remaining at the same level for the duration of the work out. Thus supporting previously mentioned benefits.

CONCLUSION

Is HIIT superior to Continuous exercise training at mitigating the effects of COPD?

Although further research is required to approve the claim that HIIT is better suited for COPD patients. Data mentioned and other studies, suggest and support that in comparison to Continuous training HIIT showed better improvements in aerobic capacity, facilitating lactate removal (due to recovery bursts) as well a decreasing C-reactive protein blood levels which rise in response to inflammation an ongoing symptom in COPD suffers [20].

References:

[1] Heyward, Vivian H. (2006) [1984]. “Designing Cardiorespiratory Exercise Programs”. Advanced Fitness Assessment And Exercise Prescription (5th ed.). Champaign, Illinois: Human Kinetics. pp. 106–107. ISBN 978-0-7360-5732-5. Retrieved June 15, 2012.

[2] Kerr, Hamish (2011). “Interval Training/Fartlek”. In Micheli, Lyle. Encyclopedia of Sports Medicine. Sage. pp. 717–719. Retrieved 14 June 2015.

[3] Atkins, William. “Interval Training”. In Longe, Jacqueline. The Gale Encyclopedia of Fitness. pp. 475–477. Retrieved 14 June 2015.

[4] Lifetime Physical Fitness and Wellness: A Personalized Program 1305887271 Wener W.K. Hoeger, Sharon A. Hoeger – 2016.

[5] Rees K, Taylor R, Singh S, et al. Exercise based rehabilitation for heart failure. Cochrane Database Syst Rev. 2004 [PMC free article][PubMed]

[6] FROM ARTICLE: High-intensity interval training (HIIT) for patients with chronic diseases – chronic disease management.

[7] Puente-Maestu L, Garcia G, Martinez-Abad Y, et al. Dyspnea, ventilatory system, and changes in dynamic hyperinflation related to the intensity of constant work rate exercise in COPD. Chest. 2005;128:651–656.  [PubMed]

[8] Aliverti A, Quaranta M, Chakrabarti B, et al. Paradoxical movement of the lower ribcage at rest and during exercise in COPD patients. Eur Respir J. 2009;33:49–60.  [PubMed]

[9] Eliason G, Abdel-Halim S, Arvidsson B, et al. Physical performance and muscular characteristics in different stages of COPD. Scand J Med Sci Sports. 2008;19:865–870.  [PubMed]

[10] Astrand PO, Rodahl K. Physical training. In: Astrand PO, Rodahl K, editors. Textbook of Work Physiology. New York, NY: McGraw-Hill; 1986. pp. 412–476.

[11] Vogiatzis I, Nanas S, Roussos C. Interval training as an alternative modality to continuous exercise in patients with COPD. Eur Respir J. 2002;20:12–19.  [PubMed]

[12] Sabapathy S, Kingsley RA, Schneider DA, et al. Continuous and intermittent exercise responses in individuals with chronic obstructive pulmonary.

[13] . Koulouris NG, Dimopoulou I, Valta P, et al. Detection of expiratory flow limitation during exercise in COPD. J App Physiol. 1997;82:723–731.  [PubMed]

[14] Vogiatzis I, Nanas S, Kastanakis E, et al. Dynamic hyper-inflation and tolerance to interval exercise in patients with advanced COPD. Eur Respir J. 2004;24:385–390.  [PubMed]

[15] Mador MJ, Krawza M, Alhajhusain A, et al. Interval training versus continuous training in patients with chronic obstructive pulmonary disease. J Cardiopulm Rehabil Prev. 2009;29:126–132.[PubMed]

[16] Varga J, Porszasz J, Boda K, et al. Supervised high intensity continuous and interval training vs. self-paced training in COPD. Respir Med. 2007;101:2297–2304.  [PubMed]

[17] Breslin E. The pattern of respiratory muscle recruitment during pursed-lip breathing. Chest. 1992;101:75–78.  [PubMed]

[18] Spahija J, de Marchie M, Grassino A. Effects of imposed pursed-lips breathing on respiratory mechanics and dyspnoea at rest and during exercise in COPD. Chest. 2005;128:640–650.  [PubMed]

[19] Ø. Rognmo, E. Hetland, J. Helgerud, J.Hoff, S.A. SlørdahlHigh intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease

Eur J Cardiovasc Prev Rehabil, 11 (2004), pp. 216

[20] P.S. Munk, E.M. Staal, N. Butt, K. Isaksen, A.I. LarsenHigh-intensity interval training may reduce in-stent restenosis following percutaneous coronary intervention with stent implantation: a randomized controlled trial evaluating the relationship to endothelial function and inflammation

[21] https://en.wikipedia.org/wiki/Emil_Zátopek

[22] https://www.sciencedirect.com/science/article/pii/S2095254616300102#bib0095

[23] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941353/