Abstract
The isometric belt squat has grown in popularity as a lower body strength assessment, given its reduction in spinal loading and limited involvement of the upper extremity compared to other whole-body isometric test variations. Previous research has identified knee angle ranges for the isometric belt squat that are more advantageous for vertical force generation. The relationship of knee angle and anteroposterior and mediolateral forces has not been established for the isometric belt squat. Since ground reaction force is three-dimensional, examination into anteroposterior and mediolateral forces will provide additional information on how force is developed for this movement as well as insight to optimal performance technique. PURPOSE: To determine the impact of knee positioning on isometric belt squat anteroposterior and mediolateral kinetics. METHODS: Thirty-three healthy, active collegiate female and male volunteers (n=33, male=9, 23.6 ± 3.7 years, 73.0 ± 16.3 kg, 1.69 ± 0.10 m) participated in this study. During familiarization, chain lengths were determined for positioning of knee angles for the maximal effort isometric belt squat: (A) 80-100, (B) 100-120, (C) 120-140, (D)140-160, and (E) 160-180 degrees. Participants completed a warm-up and 2 practice pushes. Then, participants completed 1, 5-second, maximal effort belt squat push for one of the five knee angle ranges mentioned above, followed by 2-minutes of rest. Similarly, maximal pushes for the remaining four angle ranges were completed in a random order. One-way repeated measures ANOVA were used to compare the difference in anteroposterior and mediolateral force range, absolute peak force, and time to absolute peak force between knee angle ranges. Post hoc analysis was done using Student’s LSD. RESULTS: No differences were found in the anteroposterior direction. Knee angle significantly affected the range of mediolateral force (F=9.639, p<0.0001). Mediolateral force ranges were significantly larger for all knee angles greater than 100º compared to 80-100º. Force range for angles 100-120º and 160-180º were significantly less than 120-140º; additionally, 160-180º was significantly less than 140-160º. Knee angle had a significant effect on peak mediolateral force (F=6.90, p<0.0001). Peak force at 120-140º and 140-160º was significantly greater than peak force at 80-100º, 100-120º, and 160-180º. In addition, peak force at 100-120º was significantly greater than at 80-100º. Lastly, knee angle had a significant effect on time to peak force in the mediolateral direction (F=2.993, p=0.0205). Time to peak force at angle 120-140º was significantly greater than 80-100º, 100-120º, and 160-180º. CONCLUSION: Alteration of isometric belt squat positioning by changing the knee angle did not significantly alter anteroposterior range, peak force, or time to peak force, likely due to restrictions from the apparatus set up and movement instructions. However, there were significant mediolateral force differences for range, peak force, and time to peak force based on positioning changes, suggesting this direction of force was more sensitive to knee position. All mediolateral findings had an inverted-u shape resembling the force-length relationship for active muscular contraction. It is likely the knee angles of 120-140 and 140-160 degrees resulted in a mid-range hip angle and provided peak force generation for this hip driven movement.
Recommended Citation
Eyre, Arianna N.; Treece, Madison; Mann, J Bryan; and Yentes, Jennifer M.
(2025)
"Isometric Belt Squat Knee Position Affects Mediolateral Kinetics,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
17, Article 157.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss17/157