recent internet dialogue among researchers

Posted on

Is Maximal Exercise for 75 seconds the most efficient way of burning fat?

This is an email Beth Smith (PhD student, Exercise Science at University of Michigan) sent to me. The question was posted "Is maximal exercise for 75 seconds the efficient way of burning fat?" It is really unarguable at high intensity interval training is superior to low intensity steady state training, this email suggests some interesting data and backs them up with studies and references.

"Dear All,

In addition the reply posted on the web by Joe Wright (qv) I have received some informative private replies. Here are some of the more interesting responses.

Aukje de Vrijer made a quick reply and suggested that; "at a lower intensity you will burn just as much fat, using less anaerobic energy, which makes it much more comfortable."

Dr Jon Oliver (Cardiff School of Sport) commented that; "at high-intensity the aerobic contribution will be predominantly (if not almost exclusively) from the metabolism of carbohydrate for fuel, and not fat.  The fat burning would start to come more into play during recovery". He felt that while "High-intensity activity can be useful for fat burning" it "would need to be intermittent with exercise bouts repeated a number of times" and "to get the fat loss benefits the high-intensity work would need to be performed intermittently, increasing the total overall time required (defeating your primary goal of reducing time commitment)."

Thad Buster commented that; "Another factor to consider in this discussion, is the oxygen recovery following both types of exercise.  VO2 stays elevated significantly longer after high intensity exercise.  This would suggest an elevated additional caloric expenditure following high intensity exercise as compared to lower intensity exercise." He quoted Dr. Kris Berg at the University of Nebraska Omaha who has been asking his students for years "Why don't you see fat sprinters in track and field?"

Trevor Savage suggested that; "To utilise the fat stores of the body, exercise needs to be more than 75 seconds long and at an intensity of less than 70% of maximal exertion." However, he agreed that bursts of energy do have health benefits.

Randy Dixon recommended the Tabata Protocols for anyone looking for more information. Sharon Dixon suggested a literature search for the published work of Dr Gary O'Donovan (University of Exeter UK) in this area would be useful.

Raoul Reiser pointed out that the subjects assigned to the endurance training group in <span index="41" name="incorrect" class="incorrect">Gibala</span>'s research spent considerably more time "(~ 4-fold)" exercising than those subjects assigned to sprint training.  He also mentioned some exciting advances by researchers from Colorado State University will soon be presenting preliminary data that suggest short-term sprint-interval training improves the insulin sensitivity of previously sedentary adults.

Kat Arbour (PhD Student, University of Delaware) kindly referred me to the work of Mark J Smith on "Sprint Interval Training".  Mark sent me a couple of papers complete with dozens of references. Several of the other correspondents also sent me references. Inspired by his work in this field and all of the references I have attempted to make a synopsis of the history of this field of research. Here it is.

Research has shown that the ideal duration for vigorous exercise is about 60 seconds. During a series of short high-intensity exercise tests "VO2max was reached after approximately 60 s. It is concluded that the 30 and 90 s [tests] are not strictly anaerobic although they all have a large anaerobic component" (Serresse et al, 1988).

It is vigorous exercise that increases anaerobic fitness not endurance training. Research has shown that " sprinters' anaerobic capacity was 30% larger" [than that of "endurance-trained subjects"] (Medbo, 1990). High intensity exercise is needed for burning fat off. "Plasma glucose tissue uptake and muscle glycogen oxidation increased in relation to exercise intensity.  ... Muscle triglyceride lipolysis was stimulated only at higher intensities"  (Romijn et al, 1993).

Research has shown that "high intensity exercise, either intermittent or continuous, increases recovery VO2 (L) more than prolonged low intensity exercise" (Brockman et al, 1993). High Intensity Interval Training programs also help you lose fat. A research HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with an Endurance Training (ET) program despite its lower energy cost; the decrease in the "subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program" and HIIT exercise programs " appear to favor the process of lipid oxidation" (Tremblay et al, 1994).

Japanese sports scientists designed protocols (exercise regimes such as the Tabata protocols) for training athletes using intermittent exercise bouts defined by the IE1 protocol. Their subsequent research showed that; "high-intensity intermittent training may improve both anaerobic and aerobic energy supplying systems significantly" (Tabata et al, 1996) and that " intermittent exercise ... may tax both the anaerobic and aerobic energy releasing systems almost maximally" (Tabata et al, 1997). The problem was that supra-maximal exercise was needed to achieve this. This protocol requires 6 to 7 bouts of 20-s exercise at an intensity of approximately 170% of the subject's maximal oxygen uptake with a 10 second rest between each bout).

This type of arduous exercise did not feature in public health promotion programs for obvious reasons. Highly demanding exercise regimes of this type are beyond most people who are unfit  (especially if they are over 40 and older than professional athletes). Experts argued that for the general public low intensity, long-duration exercise was preferable because it "results in a greater total fat oxidation than does moderate intensity exercise" (Thompson et al, 1998).

High intensity treadmill training has shown that in the heart lactate uptake is "increased much more after high-intensity training than after moderate-intensity training"
(Baker et al, 1998) but "high intensity, intermittent interval exercise training is more effective for stimulation of fatty acid oxidation than continuous sub-maximal exercise" (Chilibeck et al, 1998)

The use of split sessions of exercises rather than continuous exercising increases effectiveness of exercise by maximizing excess post-exercise oxygen consumption (EPOC); research has shown that the combined magnitude of EPOCs from split sessions "was significantly greater than that from CONT [continuous exercising] " (Almuzaini et al, 1998).
However, the total amount of exercise is also important. In the "Harvard Alumni Health Study" vigorous activities and large total amounts of exercise "showed the strongest reductions in CHD risk" (Sesso et al, 2000).

Despite this there is growing evidence that short burst of intense activity might also be useful.
At the onset of exercise "oxygen uptake of the exercising muscles increases after a delay of only a few seconds, and oxygen extraction peaks after approximately 50 s of exercise" (Bangsbo et al, 2000) and (as I mentioned in my initial BIOMCH message) "The duration of maximal exercise at which equal contributions are derived from the anaerobic and aerobic energy systems appears to occur between 1 to 2 minutes and most probably around 75 seconds, a time that is considerably earlier than has traditionally been suggested"  (Gastin, 2001).

Suddenly high intensity exercise appears to be competing with low intensity exercise in the health promotion stakes; "high-intensity exercise favors a lesser body fat deposition" (Yoshioka et al, 2001) and for patients with coronary artery disease "High intensity aerobic interval exercise is superior to moderate exercise for increasing VO2peak " (Rognmo e
t al, 2004). In addition, research also showed that Sprint Interval Training has beneficial effects on "aerobic" exercise capacity; "short sprint interval training (approximately 15 min of intense exercise over 2 wk) increased muscle oxidative potential and doubled endurance capacity" (Burgomaster et al, 2005).

Moreover, sprint-interval training (SIT) " is a time-efficient strategy to induce rapid adaptations in skeletal muscle and exercise performance" (Gibala et al, 2006) and the HUNT study in Norway found that "A single weekly bout of exercise of high intensity reduced the risk of cardiovascular death ... There was no additional benefit from increasing the duration or the number of exercise sessions per week" (Wisloff et al, 2006). The abstract noted that; "these results challenge the current recommendation that expenditure of at least 1000 kcal per week is required to achieve exercise-induced protection against premature cardiovascular mortality." Mark J Smith has commented that decreasing the intervals to a minute, and in turn increasing the intensity to a supra-maximal level, would yield an even greater overall benefit than that found by these researchers.

Research on weekend exercises seems to back this theory up. Activities that involve short bursts of intense activity appear to be more beneficial for the health of office workers than more leisurely pastimes like golf and gardening. In a study that compared "weekend warriors" with other sedentary workers found that "weekend warriors" had the best "health profile" but they were "the heaviest; they also were least likely to take vitamin/mineral supplements, most likely to eat red meat, and least likely to eat vegetables" (Lee et al, 2004). The most common activities undertaken by weekend warriors were tennis (38 percent), golf (13 percent) and the rest did more tranquil activities like gardening. All in all, while leisurely activities are better than nothing (and are no doubt good for the soul i.e. good for relaxing and contemplation) nothing seems to beat getting up a good old fashioned sweat on a regular basis.

In view of all this evidence two eminent scientists in the UK (O'Donovan and Shave, 2007) recently recommended that; "Policymakers have an obligation to equip the public to make fully informed decisions about physical activity and health. British physical activity guidelines should be amended because most men and women erroneously believe that moderate activity offers greater health benefits than vigorous activity."

References

1. Serresse O, Lortie G, Bouchard C, Boulay M, (1988), "Estimation of the contribution of the various energy systems during maximal work of short duration", Int J Sports Med, 1988 Dec, 9, (6), pp 456-60.

2. Medbø JI, Burgers S, (1990), "Effect of training on the anaerobic capacity", Med Sci Sports Exerc, 1990 Aug, 22, (4), pp 501-7.

3. Romijn JA, Coyle EF, Sidossis LS, Gastaldelli A, Horowitz JF, Endert E, Wolfe R, (1993), "Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration", Am J Physiol, 1993 Sep, 265, (3 Pt 1), pp E380-91. hyperlink at; http://www.ncbi.nlm.nih.gov/pubmed/8214047

4. Brockman L, Berg K, Latin R, (1993), " Oxygen uptake during recovery from intense intermittent running and prolonged walking", J Sports Med Phys Fitness, 1993 Dec, 33, (4), pp 330-6.  http://www.ncbi.nlm.nih.gov/pubmed/8035581

5. Tremblay A, Simoneau JA, Bouchard C, (1994), " Impact of exercise intensity on body fatness and skeletal muscle metabolism", Metabolism, 1994 Jul, 43, (7), pp 814-8.
http://www.ncbi.nlm.nih.gov/pubmed/8028502

6. Tabata I, Nishimura K, Kouzaki M, Hirai Y, Ogita F, Miyachi M, Yamamoto K, (1996), "Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max", Med Sci Sports Exerc, 1996 Oct, 28, (10), pp 1327-30. http://www.ncbi.nlm.nih.gov/pubmed/8897392

7. Tabata I, Irisawa K, Kouzaki M, Nishimura K, Ogita F, Miyachi M, (1997), "Metabolic profile of high intensity intermittent exercises", Med Sci Sports Exerc, 1997 Mar, 29, (3), pp 390-5. Hyperlink: http://www.ncbi.nlm.nih.gov/pubmed/9139179

8. Thompson DL, Townsend KM, Boughey R, Patterson K, Bassett DR Jr, (1998), "Substrate use during and following moderate- and low-intensity exercise: implications for weight control"
Eur J Appl Physiol Occup Physiol, 1998 Jun, 78, (1), pp 43-9.

9. Baker SK, McCullagh KJ, Bonen A, (1998), " Training intensity-dependent and tissue-specific increases in lactate uptake and MCT-1 in heart and muscle", J Appl Physiol, 1998 Mar, 84, (3), pp 987-94. http://www.ncbi.nlm.nih.gov/pubmed/9480961 <http://www.ncbi.nlm.nih.gov/pubmed/9480961?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum >

10. Chilibeck PD, Bell GJ, Farrar RP, Martin T, (1998), " Higher mitochondrial fatty acid oxidation following intermittent versus continuous endurance exercise training", Can J Physiol Pharmacol, 1998 Sep, 76, (9), pp 891-4. http://www.ncbi.nlm.nih.gov/pubmed/10066139

11. Almuzaini KS, Potteiger JA, Green S, (1998), "Effects of split exercise sessions on excess postexercise oxygen consumption and resting metabolic rate", Can J Appl Physiol, 1998 Oct, 23, (5), pp 433-43. http://www.ncbi.nlm.nih.gov/pubmed/9738129

12. Sesso HD, Paffenbarger RS Jr, Lee I, (2000), "Physical activity and coronary heart disease in men: The Harvard Alumni Health Study", Circulation, 2000 Aug 29, 102, (9), pp 975-80. http://www.ncbi.nlm.nih.gov/pubmed/10961960

13. Bangsbo J, Krustrup P, González-Alonso J, Boushel R, Saltin B, (2000), " Muscle oxygen kinetics at onset of intense dynamic exercise in humans", Am J Physiol Regul Integr Comp Physiol, 2000 Sep, 279, (3), pp R899-906. http://www.ncbi.nlm.nih.gov/pubmed/10956247

14. Gastin P, (2001), "Energy system interaction and relative contribution during maximal exercise", Sports Med, 31(10), 725-41. http://www.ncbi.nlm.nih.gov/pubmed/11547894

15. Yoshioka M, Doucet E, St-Pierre S, Alméras N, Richard D, Labrie A, Després JP, Bouchard C, Tremblay A, (2001), "Impact of high-intensity exercise on energy expenditure, lipid oxidation and body fatness", Int J Obes Relat Metab Disord, 2001 Mar, 25, (3), pp 332-9. Hyperlink http://www.ncbi.nlm.nih.gov/pubmed/11319629

16. Rognmo Ø, Hetland E, Helgerud J, Hoff J, Slørdahl S, (2004), "High 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, 2004 Jun, 11, (3), pp 216-22. http://www.ncbi.nlm.nih.gov/pubmed/15179103

17. Burgomaster KA, Hughes SC, Heigenhauser GJ, Bradwell SN, Gibala M, (2005), "Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans", J Appl Physiol, 2005 Jun, 98, (6), pp 1985-90. http://www.ncbi.nlm.nih.gov/pubmed/15705728

18. Gibala M, Little J, van Essen M, Wilkin G, Burgomaster K, Safdar A, Raha S, Tarnopolsky M, (2006), "Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance", J Physiol, 2006 Sep 15, 575, (Pt 3), pp 901-11.  http://www.ncbi.nlm.nih.gov/pubmed/16825308

19. Wisløff U, Nilsen TI, Drøyvold WB, Mørkved S, Slørdahl SA, Vatten L, (2006), "A single weekly bout of exercise may reduce cardiovascular mortality: how little pain for cardiac gain? 'The HUNT study, Norway'", Eur J Cardiovasc Prev Rehabil, 2006 Oct, 13, (5), pp 798-804. http://www.ncbi.nlm.nih.gov/pubmed/17001221
For Mark Smith's comments see "Sprint Interval Training - 'It's a HIIT' " by Mark J Smith (March 2008). Hyperlink: 
http://www.xiser.com/downloads.php

20. Lee IM, Sesso HD, Oguma Y, Paffenbarger R, (2004), "The "weekend warrior" and risk of mortality", Am J Epidemiol, 2004 Oct 1, 160, (7), 636-41.
http://www.ncbi.nlm.nih.gov/pubmed/15383407

21. O'Donovan G, Shave R, (2007), "British adults' views on the health benefits of moderate and vigorous activity", Prev Med, 2007 Dec, 45, (6), pp 432-5.
http://www.ncbi.nlm.nih.gov/pubmed/17804045 "