# Effect of low-volume exercise on hepatic steatosis in adults with obesity plus normal glucose, prediabetes or type 2 diabetes: a randomised controlled trial PMID: 39371414 Journal: BMJ open sport & exercise medicine Published: 2024 Authors: Baker C, Hocking SL, Wang X, Gerofi J, Colagiuri S, Sabag A, Molyneaux L, Xu Y, Li M, Bi Y, Min D, Johnson NA, Twigg SM ## Question Does 12 weeks of combined low-volume high-intensity aerobic exercise and progressive resistance training reduce hepatic steatosis and improve cardiometabolic outcomes in inactive adults with overweight/obesity across glucose-status strata? ## Summary This randomized trial tested whether a modest 12-week exercise program combining low-volume HIIT and progressive resistance training could reduce liver fat in inactive adults with overweight or obesity and normal glucose, prediabetes, or newly diagnosed type 2 diabetes. The program did not significantly reduce liver fat in the whole sample compared with a stretching control, although people with prediabetes showed a subgroup reduction and a weight-stable sensitivity analysis favored exercise. The program improved several cardiometabolic and fitness-related measures, including fasting glucose, triglycerides, estimated cardiovascular risk, liver enzymes, strength, and in the weight-stable analysis VO2peak. Supervised attendance was about 80%, and no intervention-related adverse events were reported. ## Population - Inactive adults with overweight/obesity and normal glucose, prediabetes, or newly diagnosed type 2 diabetes. - Sample size: 162 - Age: Mean 58.2 years (SD 12.2) - Sex: 58% women - Fitness level: Inactive; mean VO2peak about 30 mL/kg/min - Health status: BMI at least 25 kg/m2; normal glucose, prediabetes, or type 2 diabetes within 2 years ## Methodology - Parallel-group randomized controlled trial with exercise versus sham stretching control, stratified by glucose group. - 12 weeks - Community healthcare/university clinic in Sydney, Australia, with two supervised weekly exercise sessions and one unsupervised home HIIT session. - Randomized and controlled study design. ## Protocol - Low-volume HIIT plus progressive resistance training. - Modality: Stationary cycling plus machine resistance training; home HIIT used available modality. - Work intervals: One 4-min HIIT bout. - Sets or repetitions: One HIIT bout; two sets of 8-12 reps for nine resistance exercises. - Intensity: HIIT 85-95% age-predicted HRmax after ramp-in; resistance 80% 1RM. - Session duration: Not fully reported; supervised session included 4 min HIIT plus resistance training. - Frequency: 3 HIIT sessions/week; 2 supervised combined sessions/week plus 1 home HIIT session/week. - Program length: 12 weeks. - Progression: 2-week ramp from 65% age-predicted HRmax and 60% 1RM, followed by 10 weeks at target intensity; 1RM retested week 6. - Stretching control. - Modality: Stretching. - Sets or repetitions: Four stretches targeting major muscle groups. - Intensity: Low-intensity sham control. - Session duration: 15 min. - Frequency: 3 sessions/week. - Program length: 12 weeks. ## Outcomes ### Hepatic steatosis Status: no clear change Primary whole-sample hepatic steatosis change was not significantly different between exercise and control. Exercise -1.3% (SD 4.9) vs control +0.1% (SD 7.1), p=0.22. ### Prediabetes subgroup hepatic steatosis Status: improved Participants with prediabetes had a significant liver-fat reduction with exercise compared with control. Exercise -1.2% vs control +1.7%, p=0.019. ### Weight-stable sensitivity analysis Status: improved Among participants with less than 5% body-weight change, exercise reduced hepatic steatosis and improved several metabolic and fitness markers. Hepatic steatosis p=0.017; VO2peak p=0.047; HOMA-IR p=0.041; ASCVD risk p=0.008. ### Strength Status: improved Exercise increased leg press, seated row, and chest press strength compared with control. All three strength outcomes p<0.001. ### Safety Status: improved The intervention was completed with no intervention-related adverse events. 80% supervised session attendance; no related adverse events. ## Practical Insights - A very low HIIT dose can be feasible and well attended in screened, previously inactive adults when ramped up and partly supervised. - One 4-min hard interval paired with resistance training should not be marketed as a reliable liver-fat reduction protocol because the primary whole-sample endpoint was null. - Prediabetes may be a more responsive subgroup for liver-fat change than normal glucose or newly diagnosed type 2 diabetes in this protocol. - For app translation, fidelity tracking is important because the study did not measure the unsupervised weekly HIIT session. ## Limitations - COVID-19 disruptions paused and modified the intervention. - Unsupervised home HIIT adherence and intensity were not measured. - Lifestyle changes outside the intervention could influence liver fat and metabolic outcomes. - Participants were not blinded. - The protocol used resistance machines and clinical supervision. ## Safety And Adherence - No adverse events related to the intervention. - Authors recommend supervision for people with high cardiovascular risk. - COVID-19 lockdowns required pauses or telehealth maintenance for some exercise participants. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/39371414/) (pubmed) - [DOI](https://doi.org/10.1136/bmjsem-2023-001878) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11448222/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.