The sticking point in weight lifting
The “sticking point” in weightlifting represents the point in the movement where there is a disproportionate increase in difficulty that often results in compensation and lift failure. Understanding the various biomechanical and physiological factors that lead to sticking points has a significant role in injury prevention and strength rehabilitation. For this reason, the authors of the present study sought to consolidate our current understanding on three benchmark exercises: the deadlift, bench press and squat.
Overall, it was shown that when comparing muscle activity across individuals, there was no significant change in the electromyographic (EMG) patterns around the sticking points. Furthermore, the location of the sticking point varied significantly within the individual movements and depended largely on the different mechanics and lifting styles (for instance conventional deadlift versus sumo deadlift).
The bench press is a popular movement for enhancing upper extremity strength and size. Lying supine the athlete lowers a bar eccentrically towards the chest followed by concentric contraction of the pectoralii and anterior shoulder musculature. With regards to the literature it was shown that the sticking point was at approximately 30% of the total bar height. The sticking point tended to vary significantly as a result of hand width. Neutral or middle grip resulted in a sticking point that had a further vertical distance from the shoulder joint then wide or narrow grip.
The squat is an extensively studied movement that requires synergistic hip and knee flexion during eccentric descent, followed by concentric extension of the hips and knees during ascent. The sticking point was consistently (among several studies) shown to occur at an angle of thirty degrees relative to the ground. Furthermore, one study showed that there was greater variation (5-6 degrees) amongst the different lifting parameters (wide, neutral and narrow stance) than across all groups (2 degrees).
The deadlift is a complex movement requiring triple extension (hips, knee and thoracolumbar spine) often incorporated to promote gross strength and hypertrophy of the back musculature. The mean sticking point was shown to occur at an angle of sixty degrees (relative to the ground), emphasizing the importance of hip extension. Interestingly, a study has found that the sticking point does not occur at the “weakest” point of the lift. By investigating the isometric force outputs in various positions, it was shown that 3400N was exerted when lifting from the ground, followed by 4100N at knee height and 4900N at lock out.
In conclusion, the authors used an observational review approach to consolidate our current understanding of the sticking point within the deadlift, bench press and squat. By shedding light into the biomechanical and physiological limitations of these lifts it helps clinicians approach programming and rehabilitation in weightlifting populations.
> From: Kompf et al., Sports Med (2016) (Epub ahead of print). All rights reserved to The Author(s). Click here for the Pubmed summary.