Like the old adage says: sometimes, less is more.  In bodybuilding, you may be better able to progress your growth to new levels by incorporating unilateral, one-sided, isolation exercises.  

   New research explores the systems of energy production in the body and pinpoints the cause of muscle failure to it's source of chemical energy utilized to fuel vigorous contractions in the body.  

   When exercising, your body utilizes energy in the form of ATP (andosine triphospate) via the aerobic and/or anaerobic pathways for an immediate source of energy for muscle contractions.  Moderate levels of force will call upon the aerobic pathway, which utilizes oxygen in the blood to sustain the activity.  More vigorous activities, such as sprinting and weightlifting, will receive ATP energy via aerobic provisions that are supplemented by anaerobic pathways - which is a limited source of energy.

Published in the November issue of the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, the study implicates the reliance on anaerobic energy release as a key factor in the onset of muscle fatigue and impaired exercise performance...

...While the anaerobic pathways provide ATP very rapidly, their capacity is finite and must be replenished after each bout.

   Because anaerobic pathways are limiting, finite, and quickly depleted, it is important to isolate smaller muscle groups at a time, essentially "pouring" all available ATP into that one muscle.  Under these conditions, the activity may be sustained for a longer duration of time, increasing the muscle's electrical contractions as fatigue begins to set in, thus recruiting new, unfatigued, muscle fibers to perform the desired workload.  

   "Experts focusing on locomotion and whole-body activities have attributed performance limitations during running, cycling, swimming and other athletic activities that involve many muscles simultaneously to the maximum rates at which ATP can be resynthesized from all pathways and not to an impaired ability of skeletal muscles to produce force during contraction,"  said principal investigator Peter Weyand, assistant professor in kinesiology at Rice.
      
   For example, one-legged extensions will better recruit the entire musculature of each quadriceps group than two-legged extensions.  This will induce the greatest possible fatigue and fiber recruitment, leading to more muscle breakdown, more nutritious blood flow to the muscle, and induce a greater growth response.  All leading to better results - faster - than when performing extensions with both legs simultaneously.  

   Rest is crucial between each set of unilateral isolation exercises to restore your energy supply and ensure another great set.  

   And, as always...be sure to make every rep., of every set, of every exercise, count toward your goal!