The effect of resistance training with higher- and lower-loads on muscle mass and strength has been extensively studied while changes in muscle endurance have received less attention. This trial aimed to assess the effect of training load on absolute (AME) and relative muscle endurance (RME). Sixteen untrained women (22.7±3.3 yr: mean ± SD) had one arm and leg randomly assigned to train with higher-loads (HL; 80-90% 1RM), and the contralateral limbs trained with lower-loads (LL; 30-50% 1RM) thrice weekly to volitional fatigue for 10 weeks. Heavy and light load AME and RME, strength, and muscle mass were assessed pre- and post-training. Strength increased more in the HL compared to LL leg (P = <0.01), but similar increases in strength were observed between upper body conditions (P = 0.46). Lower body heavy and light load AME improved in both conditions, but HL training induced a larger improvement in heavy load AME (HL, 9.3±4.3, vs. LL, 7.5±7.1 repetitions, Time × Limb P < 0.01) and LL training induced a larger improvement in light load AME (LL, 24.7±22.2, vs. HL, 15.2±16.7 repetitions, Time × Limb P = 0.04). In the upper body, HL and LL training induced similar increases in both heavy (Time × Limb P = 0.99), and light load (Time × Limb P = 0.16) AME. Dual-energy x-ray absorptiometry showed no change in leg fat-and-bone-free mass (FBFM) for either condition, and an increase in only LL arm FBFM. AME improved in a manner specific to the training loads used. ClinicalTrials.gov (NCT04547972).

Background Many individuals develop excess skin (ES) following massive weight loss (MWL). Patient reported outcomes demonstrate that abdominal ES negatively impacts perceived physical function which is improved by abdominal body contouring surgeries (ABCS). However, the effect of ABCS on objective measures of physical function is unknown. Objectives To examine the impact of ABCSs on objective measures of physical function in individuals who have undergone MWL. Methods Patients who have undergone MWL with abdominal ES (≥ grade 2) underwent physical function assessments including 9-item modified physical performance test (mPPT), chair stand, star excursion balance test (SEBT), timed up and go (TUG), modified agility t-test, and 6-minute walk test (6-MWT). Perception of physical exertion and BODY-Q questionnaire scales were also collected. Non-surgical controls (n=21) and those who had undergone ABCS (n=6) after the first visit performed a second physical function assessment 8-12 weeks later to allow for post-operative healing. Results No ceiling or floor effect was detected for any physical function measures. Intra-class correlation (ICC ± 95% CI) was 0.78 (0.44, 0.91) for the mPPT and above 0.80 for all other measures. The effect sizes (± 75% CI) were for mPPT 0.74 (0.19, 1.28), SEBT 0.54 (0.00, 1.08), modified agility t-test -0.63 (-1.17, -0.09), and 6-MWT 0.79 (0.24, 0.13). Conclusions The mPPT and tests involving dynamic balance, agility, and walking were reliable and showed medium to large effect sizes suggesting that these tests may be sensitive to change following ABCS.