The acute and chronic effects of "NO LOAD" resistance training.
Level 2 - randomized trial
Within-subject randomized/controlled trial comparing two exercise conditions across arms in 13 participants
PubMed 27329807 · doi:10.1016/j.physbeh.2016.06.024
What was done
Thirteen participants completed 18 sessions of unilateral elbow flexion exercise. Using a within-subject design, each arm was assigned to either a NO LOAD condition (repeated maximal contractions through a full range of motion without external load) or a HIGH LOAD condition (70% of 1RM). Anterior muscle thickness at 50%, 60%, and 70% sites and 1RM strength were assessed pre- and post-intervention.
What was found
Anterior muscle thickness increased similarly from Pre to Post with no differences between conditions for the 50% [Pre: 2.7 (0.8) vs. Post: 2.9 (0.7)], 60% [Pre: 2.9 (0.7) vs. Post: 3.1 (0.7)], or 70% [Pre: 3.2 (0.7) vs. Post: 3.5 (0.7)] sites. There was a significant condition-by-time interaction for 1RM (p=0.017), with HIGH LOAD (+2.3kg) increasing more than NO LOAD (+1kg).
Why it matters
This study shows that muscle hypertrophy can occur independently of an external load when contracting maximally through a full range of motion, though heavier external loads remain necessary for optimizing maximal strength.
Limits
The sample size was very small (n=13) and limited to a single single-joint exercise (elbow flexion). Participant characteristics (sex, age, training experience) and data on acute perceptual and physiologic responses mentioned in the objective are not reported in the abstract.