Obesity blunts insulin sensitivity improvements and attenuates strength gains following resistance training in nondiabetic men

Abstract

Purpose: Impaired insulin sensitivity is central in the etiology of type 2 diabetes in people with obesity. The effectiveness of resistance training (RE) alone in improving insulin sensitivity in people with obesity is undetermined. This study aimed to determine the influence of obesity on insulin sensitivity responses to RE.

Methods: Nineteen sedentary men were allocated to Lean (BMI 22.7 ± 2.5 kg m^-2; n = 10) or Obese group (BMI 33.2 ± 3.2 kg m^-2; n = 9). Participants were evaluated before and after a 10-week supervised progressive RE (3 sets of 10 repetition maximum (RM), 3 d/wk) for insulin sensitivity indexes using an oral glucose tolerance test, body composition using anthropometrics, and strength using 1RM.

Results: Groups were matched at baseline for all variables except for body composition and absolute strength. Body fat was not changed in both groups. Matsuda insulin sensitivity index, hepatic insulin resistance, and insulin area under the curve improved by 64.3 ± 61.9 unit, - 58.2 ± 102.9 unit, 2.3 ± 4.1 unit, and - 721.6 ± 858.2 µU/ml, respectively, only in the Lean group. The increased 1RM% for leg press was greater in the Lean (49.5 ± 18.7%) than in the Obese (31.5 ± 13.9), but not different for bench press (18.0 ± 9.1% vs. 16.4 ± 6.0%, respectively).

Conclusion: Sustained obesity precludes insulin sensitivity improvements and attenuates strength gains in response to progressive RE. Additional strategies such as caloric restriction might be necessary for RE to improve insulin sensitivity, particularly at high levels of obesity.

Keywords: Adiposity; Hepatic insulin resistance; Insulin resistance; Muscle insulin sensitivity; Strength exercise.