Methods: This study included 21 healthy adults (10 men and 11 women) aged 23.2 ± 3.3 years. Participants recruited from a chiropractic institution performed 2 fatiguing protocols (with a lordotic posture or free of instructions), each immediately preceded and followed by a maximum voluntary contraction. Force data and surface electromyography of 6 muscles were recorded. The influence of posture on endurance time as well as the effect of posture on MedF/time slopes for each individual muscle throughout the first 4 30-seconds time segments was assessed.
Results: Mean time until exhaustion was 261.3 ± 149.8 seconds for the lordotic condition and 358.8 ± 206.4 seconds for the free condition. The lordotic condition induced significantly more fatigue than the free condition in 3 muscles during the first 30 seconds. However, both conditions induced similar levels of fatigue for the following 30 seconds. After the first 60 seconds, no significant differences in fatigability were noted between the 2 experimental conditions.
Conclusion: For the subjects studied, lumbar lordosis had a significant influence on trunk muscle fatigue during abdominal muscle endurance assessment. Specifically targeting the abdominal muscles during an endurance task remains a challenge.
This abstract is reproduced with the permission of the publisher; full text by subscription. Click on the above link and select a publisher from PubMed's LinkOut feature.