<i>While these high-intensity sessions
are believed to be critical to achieving maximal
performances, they cannot be performed optimally
if intervening basic endurance sessions are performed
at too high an intensity (Bruin et al., 1994). However,
high-intensity training sessions appear to be well
tolerated when variation in intensity of training is
ensured (Lehmann et al., 1991, 1992). Less experienced athletes may tend to train harder than prescribed during low-intensity sessions and not hard
enough during prescribed high-intensity sessions
(Foster et al., 2001).</i><p>-- <a href="http:&#x2F;&#x2F;fastforwardtriathlon.com&#x2F;wp-content&#x2F;uploads&#x2F;2010&#x2F;08&#x2F;Intensity-Distribution-in-Elite-Endurance-Athletes.pdf" rel="nofollow">http:&#x2F;&#x2F;fastforwardtriathlon.com&#x2F;wp-content&#x2F;uploads&#x2F;2010&#x2F;08&#x2F;I...</a><p>It&#x27;s oft-discussed in training plans across endurance sports.  Here are a few showing up in a quick search.<p><a href="http:&#x2F;&#x2F;www.cyclesportcoaching.com&#x2F;articlejunkmiles.html" rel="nofollow">http:&#x2F;&#x2F;www.cyclesportcoaching.com&#x2F;articlejunkmiles.html</a><p><a href="http:&#x2F;&#x2F;www.marathon-training-schedule.com&#x2F;heart-rate-training-zones.html" rel="nofollow">http:&#x2F;&#x2F;www.marathon-training-schedule.com&#x2F;heart-rate-trainin...</a><p><a href="http:&#x2F;&#x2F;coachlevi.com&#x2F;training&#x2F;junk-miles-what-why-avoid&#x2F;" rel="nofollow">http:&#x2F;&#x2F;coachlevi.com&#x2F;training&#x2F;junk-miles-what-why-avoid&#x2F;</a><p>Of course if you&#x27;re training for general fitness rather than to optimize performance, then zone 2 training is fine.  It burns calories and you feel like you get a workout without the pain and injury potential of higher intensity training.<p>This is an accessible review article:
<a href="http:&#x2F;&#x2F;www.fitnessforlife.org&#x2F;AcuCustom&#x2F;Sitename&#x2F;Documents&#x2F;DocumentItem&#x2F;02%20IJSPP_2010_Seiler_0009.pdf" rel="nofollow">http:&#x2F;&#x2F;www.fitnessforlife.org&#x2F;AcuCustom&#x2F;Sitename&#x2F;Documents&#x2F;D...</a>