Human Limits

This is the time of year where people in colder climates do more indoor exercise.   People also make New Year’s resolutions to get in shape.   Some serious athletes use indoor training year round because it is possible to better control the exercise intensity and the overall effort of the training session on a treadmill or bicycle ergometer.   All of this is easier now than it was 20-30 years ago before the widespread availability of well-equipped fitness centers.

However, indoor exercise can be boring and it is easy to lose fitness this time of the year.   Getting to the gym can be a hassle and short days along with the urge to sort of hibernate during the winter can make finding time to train a bit harder.   So the question is how to get the most bang for your training buck until it gets warmer and the days get longer?

One thing I do is interval train on the Treadmill 2-3 times per week.   I start slowly about 6.1 miles per hour (mph) and then use a saw tooth pattern of increasing speed.   I go up 0.5 mph on the even numbered minutes and down 0.2 mph on the odd numbered minutes.  After about 10 minutes I get to a pace of around 7.7 mph and then do 10 repeats of 1 min at 7.7 mph followed by two minutes of running in the 8.5-9.5 mph range.    The goal is for each of the two minute repeats to be at a faster speed.   In interval training lingo that is known as “descending” the workout.  A Lot of times I increase my pace by 0.1 mph every 10 breaths, so I pick it up during the fast part of the cycle.   Counting your breaths is also a good way to learn to relax while you are running fast.  Using this pattern, the first mile is almost exactly 9 minutes and then I try to do a bit over 4 miles in the next 31 minutes.  The total session takes 40 minutes.

Along these lines there is an excellent recent paper from colleagues in Denmark on the efficacy and efficiency of this type of training strategy.   They asked moderately fit people in their 30s who had been running about 15-20 miles per week to either keep doing more or less the same thing or do three sessions a week of interval training for seven weeks.  The intervals consisted of three or four 5 minute intervals with two minutes of jogging in between.  However, during the fast part of the intervals low-, moderate-, and high-speed running (<30%, <60%, and >90% of max) for 30, 20, and 10 seconds was used each minute.   This is pretty complicated to describe but the figure below shows a typical heart rate pattern for such a training session.  The heart rate shown with dashed lines is higher during 5 minute intervals and lower during the recovery period than during a steady state training session shown with the solid line.  The slight variations in heart rate during the intervals are due to the 30-20-10 changes in running speed.

Key findings included:

• The interval training group reduced training volume by 54% (14 vs. 30 km/wk about 9 vs 18 miles/wk) while CON continued the normal training.
• After seven weeks VO₂max (a key marker of fitness), and performance in a 1,500-m and a 5-km run improved by 21 and 48 s, respectively.
• Blood pressure and cholesterol values also improved more in the interval training group.

The authors concluded that:

“The present study shows that interval training with short 10-s near-maximal bouts can improve performance and V̇O₂max despite a ∼50% reduction in training volume. In addition, the interval training regime lowers resting systolic blood pressure and blood cholesterol, suggesting a beneficial effect on the health profile of already trained individuals.”

Summary

Relatively brief but high intensity interval training is a great way to maintain and even improve your fitness in the winter.  For people with competitive goals it means that you will be ready for more and harder training as the days get longer and warmer and you head outside in March or April.   There is also a growing body data about the value of higher intensity exercise for people of every ability level and age group.    A New Year’s resolution that includes interval training might be a good way to start.

This entry was posted on Thursday, December 27th, 2012 at 6:48 am and is filed under Current Events, Research and Health. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.