Is Handgrip Strength Variation Sensitive To Leg Strength And Lean Mass Changes In Post-bariatric Surgery Patients?

Bariatric surgery (BS) is an effective therapy for obesity, promoting significant weight loss. However, the loss of lean body mass (LBM), more specifically skeletal muscle, seems to be a detrimental effect. Skeletal muscle plays a pivotal role in basal metabolic rate, weight regain risk and physical function. Handgrip strength is a valid and easy surrogate for LBM, overall functionality and even mortality. However, it is unknown if it could be a valid surrogate for LBM and lower limb strength variations in post-BS patients. PURPOSE: To assess the correlation between changes in handgrip strength, lower limb strength and LBM in post-BS patients after a resistance training program. METHODS: Six post-BS patients were assessed before and after a 16-week resistance training program for upper (handgrip dynamometer; Saehan SH5001, Masan, South Korea) and lower limb (isokinetic dynamometer 60°/second knee extension/flexion; Biodex System 4 Pro, NY, USA) muscle strength. Whole-body LBM was assessed by DXA (Hologic Horizon, Bedford, MA, USA). Pearson correlation coefficient was calculated to determine correlations between changes in handgrip strength, lower limb strength and whole-body LBM. RESULTS: After the exercise training program mean handgrip strength increased 0,25 ± -1,64 kg and, mean LBM increased 0.56 ± -0,97 kg. Mean leg extension and flexion peak torque increased 18,53 ± 14,73 N.m and 5,10 ± 4,47 N.m, respectively. Handgrip strength was negatively correlated, although not reaching significance, with leg extension (r = -0.743; p = 0.091) and leg flexion (r = -0.546; p = 0.263) peak torque variation. It was also negatively correlated with LBM change (r = -0.664; p = 0.150). Although not statistically significant, there was a trend for LBM changes to correlate positively with changes in leg extension (r = 0.644; p = 0.167) and leg flexion strength variation (r = 0.289; p = 0.579). CONCLUSIONS: Handgrip strength changes after a resistance training program do not seem to be a sensitive surrogate of whole-body LBM and lower limb strength variations in post-BS patients. Project supported by CIAFEL, ITR, Faculty of Sport, University of Porto (FADEUP), S. João Academic Hospital Center (HSJ), Portugal. Tiago Montanha and Saira Waqqar are funded by Fundação para a Ciência e Tecnologia (FCT) grants 2021.05532.BD and 2023.00444.BD, respectively.