# Maximum Heart Rate- and Lactate Threshold-Based Low-Volume High-Intensity Interval Training Prescriptions Provide Similar Health Benefits in Metabolic Syndrome Patients PMID: 36900716 Journal: Healthcare (Basel, Switzerland) Published: 2023-02-28 Authors: Reljic D, Frenk F, Herrmann HJ, Neurath MF, Zopf Y ## Question In obese adults with metabolic syndrome, does low-volume HIIT prescribed from a submaximal lactate-threshold test produce cardiometabolic and quality-of-life benefits comparable to HIIT prescribed from measured maximum heart rate? ## Summary This randomized clinical trial substudy compared two ways of prescribing low-volume HIIT intensity in adults with obesity and metabolic syndrome: percentages of measured maximum heart rate versus heart rate at a submaximal lactate threshold. Both exercise groups completed two supervised 14-minute cycling sessions per week for 12 weeks, while all groups also received nutritional counseling. The two HIIT prescriptions produced similar improvements in VO2max, exercise power, blood pressure, glycemic markers, metabolic syndrome severity score, waist circumference, and quality of life, with high adherence and no LOW-HIIT-related adverse events. ## Population - Adults with obesity, metabolic syndrome, and a mainly physically inactive lifestyle. - Sample size: 75 - Age: At least 18 years; exact mean age not available in extracted text. - Sex: Mixed female and male sample. - Fitness level: Mainly physically inactive; low baseline VO2max around 22 mL/kg/min. - Health status: Obese metabolic syndrome patients without heart disease or other major exercise contraindications. ## Methodology - Randomized controlled clinical-trial substudy with three groups: HIIT prescribed by maximum heart rate, HIIT prescribed by lactate threshold, and non-exercising control. - 12 weeks, with pre-intervention and post-intervention testing in the week after the program. - Hector-Center for Nutrition, Exercise and Sports at University Hospital Erlangen; exercise sessions were supervised in an exercise center. - Randomized and controlled study design. ## Protocol - LOW-HIIT HRmax or lactate-threshold cycling. - Modality: Electronically braked cycle ergometer. - Work intervals: Five 1-minute vigorous bouts. - Recovery: One-minute recovery phases between bouts. - Sets or repetitions: 5 intervals per session. - Intensity: HIIT-HR: 80-95% HRmax; HIIT-LT: 95-105% heart rate at lactate threshold. - Session duration: 14 minutes including 2-minute warm-up and 3-minute cool-down. - Frequency: 2 sessions per week. - Program length: 12 weeks. - Progression: HIIT-HR progressed every 4 weeks from 80-85% to 85-90% to 90-95% HRmax; HIIT-LT progressed from 95-100% LT HR in weeks 1-4 to 100-105% LT HR in weeks 5-12. - Non-exercising control with nutritional counseling. - Modality: No exercise intervention. - Program length: 12 weeks. ## Outcomes ### VO2max Status: improved Relative VO2max improved by 3.6 mL/kg/min in HIIT-HR and 3.7 mL/kg/min in HIIT-LT, while control did not improve. Both HIIT within-group changes p < 0.001; group-by-time interaction for relative VO2max p < 0.001, eta2 = 0.39. ### Exercise power Status: improved Both HIIT groups improved Wmax, WVT1, and WVT2; HIIT-LT also improved WLT. HIIT-HR and HIIT-LT Wmax changes were 25 W and 26 W, both p < 0.001; WLT in HIIT-LT increased 12 W, p = 0.012. ### Blood pressure Status: improved Both HIIT groups reduced systolic and diastolic blood pressure; control did not change. SBP reductions were -11 mmHg and -13 mmHg, both p < 0.001; DBP reductions were -8 mmHg and -10 mmHg, both p < 0.001. ### Glycemic and metabolic syndrome markers Status: improved Both HIIT groups reduced HbA1c, serum insulin, HOMA-index, and MetS z-score, whereas control did not show significant changes. HbA1c changed -0.2% (p = 0.012) and -0.3% (p < 0.001); HOMA-index changed -1.3 (p = 0.005) and -1.0 (p = 0.014); MetS z-score changed -1.9 and -2.5, both p < 0.001. ### Body composition Status: mixed All groups lost weight, but only the HIIT groups significantly reduced fat mass and waist circumference, with larger waist reductions than control. Weight loss: HIIT-HR -3.9 kg, HIIT-LT -5.6 kg, CON -2.6 kg. Waist reduction versus control: -7 cm in HIIT-HR (p = 0.010) and -8 cm in HIIT-LT (p < 0.001). ### Quality of life Status: improved EQ-VAS improved in both HIIT groups and did not significantly change in control. EQ-VAS increased 10 points in HIIT-HR (p = 0.029) and 11 points in HIIT-LT (p = 0.002). ### Safety and adherence Status: improved Compliance was high in both exercise groups and no LOW-HIIT-related adverse events were observed. Attendance was 96 +/- 6% in HIIT-HR and 94 +/- 8% in HIIT-LT. ## Practical Insights - A 14-minute cycling HIIT session with only 5 minutes of hard work can improve VO2max and several cardiometabolic markers over 12 weeks in screened metabolic syndrome patients. - For users who cannot or should not complete maximal exercise testing, submaximal threshold-based intensity prescription may be a clinically viable alternative. - Twice-weekly supervised sessions with progressive intensity targets achieved high adherence in this clinical sample. ## Limitations - Nutritional counseling in all groups may confound body composition and metabolic changes. - The protocol used supervised cycle ergometer sessions and clinical testing, limiting direct translation to unsupervised app workouts. - The sample excluded several higher-risk conditions and should not be generalized to contraindicated patients. - The final analysis included 58 patients after 17 dropouts. ## Safety And Adherence - No adverse events related to LOW-HIIT were observed. - The study excluded patients with heart disease, pregnancy, cancer, substantial musculoskeletal disorders, or other major contraindicating health limitations. - All exercise sessions were supervised and heart-rate monitored. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/36900716/) (pubmed) - [DOI](https://doi.org/10.3390/healthcare11050711) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10000820/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.