{"id":6032,"date":"2014-10-24T09:04:59","date_gmt":"2014-10-24T09:04:59","guid":{"rendered":"https:\/\/fitproblog.mysites.io\/1000-calories-burn-energy-part-2\/"},"modified":"2014-10-24T09:04:59","modified_gmt":"2014-10-24T09:04:59","slug":"1000-calories-burn-energy-part-2","status":"publish","type":"post","link":"https:\/\/www.fitpro.com\/blog\/1000-calories-burn-energy-part-2\/","title":{"rendered":"1,000 calories to burn: Energy expenditure during class by Tony Lycholat, part 2"},"content":{"rendered":"

If haven’t read part 1, you can find it\u00a0here<\/a><\/p>\n

What about HIIT?<\/h2>\n

Clearly, with all-out efforts (as with high-intensity\u00a0interval training [HIIT]) you could\u00a0conceivably exercise at higher intensities\u00a0yet for a reduced total time, since you\u00a0will often be working anaerobically and\u00a0your blood lactate levels will rise steadily\u00a0if there are limited recovery periods.\u00a0Remarkably, given the recent promotion\u00a0and marketing of HIIT in the UK, very little\u00a0published research exists using this class\u00a0format, although some rather unscientific\u00a0claims have been made by extrapolating\u00a0data from laboratory studies on elite\u00a0athletes training on a cycle ergometer in\u00a0the laboratory.<\/p>\n

\n

Even if working at\u00a0a high intensity for\u00a0three times as long\u00a0were possible, the\u00a0average total energy\u00a0expenditure would\u00a0be 720-1,080kcal<\/p>\n<\/blockquote>\n

However, two relevant studies have\u00a0been carried out recently in the US. One\u00a0(by Olsen) is the subject of an abstract\u00a0(i.e., not in full peer-reviewed journal\u00a0format), while the other (by Porcari) is\u00a0described in a letter to the editor of the\u00a0Journal of Sports Sciences and Medicine<\/em>.\u00a0Olsen arrives at the conclusion that the\u00a0average energy expenditure in her group\u00a0of 13 men and three women was 54kcal\u00a0for the typically recommended four-minute\u00a0Tabata class protocol. Porcari\u2019s\u00a0research as described provides a little\u00a0more detail. He took 16 trained volunteers\u00a0(eight men; eight women) and used a\u00a0laboratory-based assessment to arrive\u00a0at heart rate and oxygen consumption\u00a0values for each subject, later using these\u00a0data to predict oxygen uptake and energy\u00a0expenditure during the Tabata class. The\u00a0workout consisted of four four-minute\u00a0segments, with each segment comprising\u00a0typical exercises (e.g., high-knee run,\u00a0burpees, box jumps, jumping jacks).\u00a0Subjects completed as many repetitions\u00a0of each exercise as possible, followed by\u00a010 seconds of rest and, after each four-minute\u00a0segment, there was one minute\u2019s\u00a0rest. Blood lactate was measured at the\u00a0end of each four-minute segment, along\u00a0with ratings of perceived exertion (RPE)\u00a0using the 6-20 scale. Energy expenditure\u00a0was calculated using the HR\/oxygen\u00a0consumption equations created for each\u00a0subject in the lab, with energy expenditure\u00a0being calculated (indirectly) assuming a\u00a0constant 5kcal\/litre of oxygen consumed.<\/p>\n

In this study, energy expenditure\u00a0averaged 14.5kcal per minute with\u00a0total energy expenditure ranging from\u00a0240-360kcal for the 20-minute workout.\u00a0Heart rates averaged 86% of HR max,\u00a0predicted maximum oxygen uptake was\u00a074%, RPE was 15.4 and blood lactates\u00a0averaged 12.1. In short, these were hard\u00a0workouts for the subjects, with evidence\u00a0of a progressively accumulating lactate\u00a0concentration. Even if working at this\u00a0intensity for three times as long were\u00a0possible (and the lactate data suggests\u00a0not), the average total energy expenditure\u00a0the group would be 720-1,080kcal.\u00a0This is entirely consistent with their\u00a0maximum oxygen uptake data as provided\u00a0by Porcari.<\/p>\n

Afterburn<\/h2>\n

Of course, calories expended during\u00a0exercise are not the only consideration,\u00a0since advocates of HIIT argue that the\u00a0simplistic calculations carried out (as\u00a0above) ignore the \u2018afterburn effect\u2019 \u2013 or\u00a0what is more technically known as excess\u00a0post-exercise oxygen consumption\u00a0(EPOC). Exercise recovery has two stages:\u00a0the most immediate initial phase (\u2018getting\u00a0your breath back\u2019) lasting a few minutes\u00a0followed by a slower second phase lasting\u00a0a number of hours, which appears to be\u00a0determined by exercise intensity and\u00a0duration as the body restores itself to\u00a0its pre-exercise level and adapts to the\u00a0specific training stimuli associated with the\u00a0workout.<\/p>\n

Again, somewhat extravagant\u00a0claims have been made for the number\u00a0of extra calories that may be attributed\u00a0to EPOC. It is possible that claims for\u00a0\u2018doubling\u2019 the energy expenditure come\u00a0from a misreading of some of the early\u00a0research literature that looked at the\u00a0potential 100% increase in EPOC with\u00a0increased intensity. A recent review of the\u00a0literature by the National Strength and\u00a0Conditioning Association (NSCA) notes\u00a0that EPOC values expressed in terms of\u00a0the percentage of total kcal expended in\u00a0the workout are modest, accounting for\u00a0less than 15% of total energy expenditure.\u00a0The NSCA concludes, \u201cMany popular\u00a0infomercials and programmes base their\u00a0weight-loss and fat-burning claims on\u00a0increased EPOC, yet EPOC values are\u00a0modest compared to the actual energy\u00a0expenditure from the exercise session\u00a0itself, accounting for only 6-15% of the\u00a0total energy cost. There is no evidence\u00a0that EPOC alone can significantly\u00a0contribute to weight loss.\u201d\u00a0<\/span>Based on\u00a0the current evidence, a reasonable rule\u00a0of thumb would be to argue for any\u00a0extra kcal associated with EPOC to be\u00a0considered as being 10% of workout kcal.\u00a0In the case of Porcari\u2019s Tabata research\u00a0described earlier, this would be 10% of\u00a0240-360kcal = 24-36 extra kcal per session.<\/p>\n

Activity monitors and\u00a0energy expenditure<\/h2>\n

Advances in technology have led to\u00a0the increased availability of heart\u00a0rate monitors and activity trackers\u00a0that purport to measure your energy\u00a0expenditure. None of them \u2018measure\u2019\u00a0energy expenditure; rather they measure\u00a0something else such as heart rate and\/or use a sensor (accelerometer) to track\u00a0motion disturbances. This information is\u00a0then used in an equation \u2013 an algorithm\u00a0\u2013 perhaps alongside other personal\u00a0data (e.g., weight, age, \u2018fitness level\u2019) to\u00a0estimate likely energy expenditure. As a\u00a0consequence, such monitors can never\u00a0be entirely accurate. A recent study that\u00a0looked at the calorie-counting accuracy\u00a0of eight activity monitors reported an\u00a0error range of 9.3-23.5% 8<\/span>. Note that\u00a0errors associated with algorithms that\u00a0place greater emphasis on heart rate\u00a0will probably over-estimate energy\u00a0expenditure in classes that involve\u00a0resistance training, sustained isometric\u00a0contractions and exercises above shoulder\u00a0height, since the heart rate response\u00a0in each of these situations is no longer\u00a0directly related to the oxygen cost of such\u00a0activities. In short, heart rate is only a good\u00a0indicator of exercise intensity\/oxygen cost\u00a0during whole-body, rhythmical aerobic\u00a0exercise.<\/p>\n

\n

The extra energy\u00a0expenditure\u00a0associated with\u00a0EPOC is probably\u00a0around 10% of the\u00a0total kcal expended\u00a0in the workout<\/p>\n<\/blockquote>\n

Conclusion<\/h2>\n

Can some people exercise at sufficient\u00a0intensity for an hour to expend 1,000kcal?\u00a0Yes \u2013 but these will be people who have\u00a0a big, aerobic \u2018engine\u2019 and are motivated\u00a0to work hard. For most people, it is likely\u00a0that typical energy expenditure during\u00a0class (or physical activity generally) will be\u00a0more modest and probably around half of\u00a0this value. The available evidence indicates\u00a0that extra energy expenditure associated\u00a0with EPOC is probably around 10% of\u00a0the total kcal expended in the workout.\u00a0Activity and heart rate monitors vary in\u00a0their accuracy and may overestimate\u00a0energy expenditure considerably if used\u00a0during activities that include resistance\u00a0training or sustained small muscle group\u00a0or isometric work above shoulder level.<\/p>\n","protected":false},"excerpt":{"rendered":"

If haven’t read part 1, you can find it\u00a0here What about HIIT? Clearly, with all-out…<\/p>\n","protected":false},"author":1,"featured_media":6033,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[69],"tags":[112,113,71,75],"class_list":{"0":"post-6032","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-cardio-strength","8":"tag-1000-calories","9":"tag-energy","10":"tag-hiit","11":"tag-triathlon-training"},"acf":[],"_links":{"self":[{"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/posts\/6032"}],"collection":[{"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/comments?post=6032"}],"version-history":[{"count":0,"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/posts\/6032\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/media\/6033"}],"wp:attachment":[{"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/media?parent=6032"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/categories?post=6032"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fitpro.com\/blog\/wp-json\/wp\/v2\/tags?post=6032"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}