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exercise trends

INFO PANEL 2 : Literature review A

UT University’s review of 45 published journal articles, carried out on behalf of Les Mills, focused on 24 papers that compared HIT with steady-state moderate intensity

exercise. Although the studies covered groups as diverse as elite athletes and post-cardiac event patients, the authors focused on moderately trained recreational athletes through to those with general metabolic syndrome (including obesity and hypertension) as more representative of the general population. The training studies ranged from two to 20 weeks in duration, with training frequency typically three to fi ve sessions a week. Some studies used supra-maximal intensity (up to a reported 170 per cent of VO2

of around 90 per cent VO2

max). However, most used ‘work’ phases max – also described as 15–17 out

of 20 on a self-rating scale of perceived exertion (hard to very hard). Sessions generally lasted around 40 minutes, including work and recovery phases: work phases lasted eight seconds to four minutes, but were typically 30 seconds to two minutes; recovery phases were mostly one to four minutes of light to moderate intensity exercise (around 70 per cent HR max). In terms of results, in several studies HIT produced 5–10 per cent greater increases in VO2

max than moderate exercise,

often in less total time. In some cases even greater differences were observed. Where the steady state group did experience signifi cantly greater increases in VO2

to very big differences in training volume”. max “it was patently owing

Work phases typically last between 30 seconds and two minutes

In all cases, HIT produced greater

improvements in anaerobic fi tness, insulin sensitivity, endothelian function and body fat levels, with signifi cantly greater reductions also observed in systolic and diastolic pressure in several studies. Although often anecdotally quoted as a benefi t of HIT, only one study specifi cally examined EPOC (excess post-exercise oxygen consumption) and found no signifi cant difference compared with steady-state moderate intensity exercise. Several of the papers commented anecdotally that subjects

typically reported their enjoyment of interval-style training more than steady-state training, leading to good adherence. The authors of the review found no evidence that repeat high intensity exercise bouts had a harmful effect on any of the populations encountered within the studies. They also found no evidence that exercise intensity alone has a negative effect on resting hormone levels (testosterone, cortisol etc).

the shape and tone you dream about.” (See info panel 1, p40, and info panel 2, above, for further details.) Huntington adds: “Interval training has the potential to burn more calories than conventional aerobic/strength training and is an effective means of improving strength/muscular endurance. In addition, it has always delivered faster results. However, all this is at the potential expense of injury and endocrine burnout. It takes quite some time to adapt to such workouts, and in most cases adherence is less time than the required time to adaptation. If we are to bring it into the gym environment, we need to make it fun so people will continue to do it, thereby gaining a cumulative effect.” There is also an argument that,

HIT: Perceived exertion levels of 15–17 out of 20

particularly for those seeking performance training, a HIT circuit may not deliver optimum results. Huntington continues: “In the late 80s and early 90s, Keiser developed the XPress Circuit to meet the needs of the time-conscious, non- elite member. This was done in the full knowledge that circuit training will always compromise the true effectiveness of the fi ve S’s – strength, speed, skill, stamina, suppleness – when they are not done as discreet parts of a programme. Does this make HIT or circuit training bad? Absolutely not. It just means that the best results you can get will be less than the best result you could achieve by focusing on any one of the fi ve S’s individually.”

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A BROAD APPEAL For non-elite athletes, however, the sort of benefi ts outlined earlier will already be very compelling. Not only that, but the AUT University/Les Mills review paper also highlights benefi ts for a far more diverse range of exercisers than might have been expected (see info panel 2, above). Gym-based use of HIT could, it seems, be of relatively broad appeal. So how can the hi-tech science of HIT be translated into the gym environment? How do we create a programme that’s suitable for a non-elite audience, ensuring it’s safe for the average gym-going participant? We’ll investigate ways to bring HIT to the gym in the second part of this series, which will appear in the August issue of Health Club Management.

kate cracknell july 2012 © cybertrek 2012



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