Following on from Should you be doing HIT training? Part 1, which looked at how HIT is useful for sports performance, this time I’m looking at how it benefits people wanting to improve their general health and fitness. If you want to lose weight or improve your health, it’s worth having a rough understanding of the physiological effects of HIT training.
This is where the headline-grabbing investigations and episode of the BBC’s Horizon programme by Michael Mosley come in. While the initial findings about the effects of HIT training were of interest to sports performance, the health benefits and time-efficient aspects of HIT training also made it an important area of research for improving public health and a number of studies looking at how the approach could benefit the general population have been carried out.
A study in 2011 by Richard Metcalfe and his team of researchers at Heriott-Watt University1 took the HIT training principle and asked, just how little high-intensity training is needed to improve health markers? They dubbed their approach REHIT (or Reduced Exertion HIT) and their test reduced the total duration of the high-intensity intervals of 02:40 per session in the Tabata protocol to a tiny 00:10, increasing to 00:40 per session over the course of 4 weeks.
Micro-sessions with 1-2 intervals lasting 10-40 sections improved insulin sensitivity by 28%
Astonishingly, these micro-sessions three times per week improved VO2 Max by 12-15% in women and men respectively, and improved insulin-sensitivity by 28%. VO2 Max is a measure of aerobic capacity and represents the volume of oxygen your body can take in per minute, relative to your bodyweight. Insulin sensitivity is an important measure in calculating the risk of someone developing Type II Diabetes so it’s easy to see why this research garnered so much attention.
Michael Mosely in his investigation for Horizon followed a HIT training programme somewhere between the Tabata protocol and Metcalfe’s REHIT, completing 3 x 20s maximal effort intervals on an exercise bike 3 times a week for 4 weeks and in line with the Metcalfe study, found his insulin sensitivity fell by 24% which was really meaningful for Mosely given he has a family history of diabetes.
Different people have different adaptation responses to training
If you’ve ever trained with a friend and completed the same sessions but not seen the same results, it might not come as a huge surprise to you that different people respond differently to training. While there was a big improvement in insulin sensitivity, Mosely’s aerobic fitness as measured by VO2 Max, did not improve significantly. Jamie Timmons, a Professor of Biology he was working with at Birmingham University, explained that this was due to Mosely’s genetic profile. Timmons has studied2 response to aerobic training and found different genetic profiles respond to different forms of training and his profiling of Mosely’s DNA suggested that HIT training was not the ideal training to improve VO2 Max for him, although the insulin sensitivity improvements were extremely worthwhile.
What does this mean for me?
We know from early studies that very intense sessions of HIT training had remarkable improvements in performance for well-trained athletes, but research that has followed to establish whether using the same principle but adapting the protocol for the general public has found that other variants of the protocol which use short, high-intensity bursts can also have a profound impact on vital functions.
It would be misleading to suggest that a few sessions of HIT training each week will burn fat much faster than other forms of cardiovascular workout – the length of the session plus factoring in the seductive-but-oversold ‘afterburn’ effect or EPOC is still likely to burn fewer calories overall compared to an hour of steady running for example, however it’s likely that incorporating some HIT will jump-start some improvements in aerobic and anaerobic capacity, making longer sessions more manageable and more fun.
As with any new training approach, the key is to find out what works for you. Here’s how:
- Test yourself before starting a HIT programme and see what improvements you’ve had after a 6-8 week block of training.
- Don’t be put off if the benefits aren’t obvious – you can’t measure body functions like insulin sensitivity at home but there should be improvements here.
- Learning about your body is a valuable outcome. The fitness journey is about getting to know your body better – if you don’t seem to make great strides, you’ve learned something and you can move on.
- Try different approaches to find out what works best for you. This also gives you a great excuse to mix it up and try something different. Variety is one of the best ways to stay motivated and to continuously challenge your body with something new.
Want help putting it into practice? Come and train with me at the London Aquatics Centre or around the Olympic Park! Contact me to arrange your free consultation.
- Metcalfe RS, Babraj JA, Fawkner SG, Vollaard NB. “Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training.” Eur J Appl Physiol. 2012 Jul;112(7):2767-75. http://www.ncbi.nlm.nih.gov/pubmed/22124524 accessed 05/12/2015.
- James A. Timmons, Steen Knudsen, Tuomo Rankinen, Lauren G. Koch, Mark Sarzynski, Thomas Jensen, Pernille Keller, Camilla Scheele, Niels B. J. Vollaard, Søren Nielsen, Thorbjörn Åkerström, Ormond A. MacDougald, Eva Jansson, Paul L. Greenhaff, Mark A. Tarnopolsky, Luc J. C. van Loon, Bente K. Pedersen, Carl Johan Sundberg, Claes Wahlestedt, Steven L. Britton, Claude Bouchard “Using molecular classification to predict gains in maximal aerobic capacity following endurance exercise training in humans.” Journal of Applied Physiology Jun 2010, 108 (6) 1487-1496; DOI: 10.1152/japplphysiol.01295.2009 http://jap.physiology.org/content/108/6/1487 accessed 05/12/2015