Renee Walton

Date Approved


Date Posted


Degree Type

Open Access Senior Honors Thesis


Health Promotion and Human Performance

First Advisor

Christopher Herman

Second Advisor

Dennis Kerrigan


Prior studies in patients following bariatric surgery have demonstrated an associated reduction in lean muscle mass concomitant with total weight loss. Less described are any changes of skeletal muscular strength following bariatric surgery and if changes in strength are propmiional to total weight loss. Purpose: To describe changes in upper and lower body strength following weight loss surgery. Methods: Seven subjects (age (yr) = 48 ±13; weight (kg)= 137.4 ± 5.4; BMI (kg/m2 ) =50 ±5) who underwent laparoscopic bariatric surgery at Henry Ford Hospital (6 Roux-en-Y bypass and 1 vetiical sleeve) were assessed. Within 30 days prior to surgery upper and lower body strength were assessed, respectively, by performing a one repetition max test on an isotonic chest press (CP) machine (Cybex) and a single-leg knee extension (KE) using an isokinetic dynamometer (Biodex). Strength tests were repeated three months following surgery. AN OVA tests were used to compare differences in strength between baseline, three months, and six months. Results: At three months there was a 20% weight loss (p < 0.001), and 25% reduction ofBMI (p < 0.001). Overall strength was reduced at three months. The absolute decrease in strength was significant only for peak torque at 120° · sec·1 • All other strength measures trended towards significance. However, when body weight was controlled for, relative strength for all tests were no different before and after bariatric surgery. Conclusion: This preliminary data shows reductions in absolute strength following weight loss surgery, are related to total weight loss. Future studies should examine if these changes persist beyond three months post surgery as well as if a post-operative strength-training program can minimize this impact.