Effect of aerobic exercise on insulin resistance and centra1 adiposity disappeared after the discontinuation of intervention in overweight women

Purpose： This study aimed to assess whether the benefits of exercise on central adiposity and insulin resistance （HOMA-IR） are maintained after discontinuation of intervention in the overweight/obese （OWOB） women. Methods： The study subjects were from 2 independent studies with similar aerobic exercise （AE） intervention programs. In study I, I50WOB postmenopausal women with pre-diabetes （body mass index, BMI = 24-33 kg/m2, aged 52-65 years） completed an 8-month exercise intervention and were followed for 2 years after the intervention. In study lI, 12 OWOB （BM1 = 25-35 kg/m2, aged 30-50 years） premenopausal women participated in a 6-week AE and were followed for 4 years after the intervention. The exercise program consisted of progressive AE with intensity of 60%-75% of initial fitness level, 30-60 min/time and 3-5 times/week. Fat mass （FM） was assessed by Dual Energy X-ray Absorptiometry （DXA Prodigy; study I） or bioelectrical impedance device （Inbody 720; study II）. Plasma glucose and insulin were assessed by chemiluminescent immunoassay and HOMA-IR was calculated. Results： Both 8-month and 6-week moderate AE were effective in reducing HOMA-IR （-18.9%, p = 0.012 and -26.7%, p = 0.046, respectively）, and 8-month AE reduced FM at upper abdominal region （-6.2%, p = 0.021）. However, these improvements were not maintained in either study at the follow-up. Conclusion： The AE program used in these studies was effective to reduce insulin resistance and/or FM in central body region among overweight and obese women. However, when exercise intervention was discontinued, the beneficial effects following both short- and long-term intervention disappeared. Thus maintaining exercise seems to be required if one wants to reap the benefits of exercise in the long-term.

目的:本研究旨在分析有氧运动干预停止后,运动对超重/肥胖女性腹部脂肪含量和胰岛素抵抗(HOMA-IR)的作用是否消失。方法:研究对象来自2项相似的独立有氧运动干预研究。研究Ⅰ中,15名绝经后并患有糖尿病的超重,肥胖女性(BMI=24-33 kg/m^2,年龄52-65岁)完成为期8个月的有氧运动干预,并在干预停止后2年随访。研究Ⅱ中,12名绝经前的超重/肥胖妇女(BMI=25-35 kg/m^2,年龄30-50岁)接受为期6周的有氧运动干预,并在干预停止后4年随访。运动方案中,运动强度为60%-75%最大摄氧量、每次30-60 min,每周3-5次运动。通过双能X线(DXA Prodigy;研究1)或生物电阻抗(Inbody 720;研究Ⅱ)测定脂肪含量。用化学荧光免疫法测定血浆葡萄糖和胰岛素水平,算出胰岛素抵抗水平(HOMA-IR)。结果:8个月和6周中等强度有氧运动干预均能有效降低HOMA-IR(-18.9%,p=0.012;-26.7%,p=0.046),8个月的有氧运动干预使上腹部脂肪含量降低(-6.2%,p=0.021),但这些作用在干预停止后的随访中均消失。结论:有氧运动干预能有效降低超重/肥胖女性的腹部脂肪含量和胰岛素抵抗水平。但无论短期还是长期有氧运动,在干预停止后其产生的益处都消退。因此,为获得长期益处,有必要维持长期有氧运动。