Exercise as it relates to Disease/Is HIIT training an effective intervention for blood pressure and central obesity? A comparison of males and females

This is a critique of Adriyani et al's article "Sex Differences in Blood Pressure and Body Composition after Short-Term High-Intensity Interval Training at the University of Canberra for unit 8340; Health, Disease and Exercise.

What is the background to this research?
Hypertension (high blood pressure), is a disease state wherein there is an increased outward pressure on the walls of blood vessels. Hypertension is often caused by vessel narrowing resulting from abdominal obesity, glucose intolerance and metabolic diseases. The American College of Sports Medicine (ACSM) position stand defines hypertension as greater than or equal to 140 mmHg in systolic (SBP) and 90 mmHg in diastolic blood pressure (DBP) among adults and supports regular physical activity for the prevention and treatment of hypertension.

Adriyani et al's paper discusses the effects of High Intensity Interval Training (HIIT) as an intervention for hypertension and central obesity in Indonesian male and female populations. HIIT is an exercise modality characterised by short to moderate periods of vigorous anaerobic exercise with brief intermittent recovery periods. Adriyani's study aims to outline the effects of an alternative, increasingly popular exercise modality amongst clinical populations where hypertensive exercise prescription traditionally centers on aerobic endurance exercise.

Exploring interventions with optimised, engaging exercise modalities to encourage exercise adherence among both males and females is vital in approaching preventable disease such as hypertension. Hypertension has a high association with prevalent comorbidities such as cardiovascular disease and metabolic syndrome, that may lead to debilitating lifestyle ailments such as stroke, myocardial infarction and diabetes, whilst placing a large economic burden on global healthcare.

Where is the research from?
This study was conducted in Bandung among Indonesian populations, which is important when comparing males and females from Indonesian and Australian cultures. This research was published in the "Jurnal Pendidikan Jasmani dan Olahraga"

Adriyani has 3 publications in health literature with no notable landmark research, whereas her associates Dana and Iskandar have published even fewer works. Lead author Riza Adriyani works as a public health, sports doctor at a gym (BKOM) in Bandung after studying sports science at the Bandung Institute of Technology. Adriyani appears to have no commercial or personal conflict of interest in conducting this study.

What kind of research was this?
This research is a short duration experimental intervention cohort study. This is characterised by Adriyani et al's use of pre and post data collection, selection criteria, as well as the absence of a control group when comparing the effectiveness of an intervention among two different cohort with a similar disease state.

Randomised Control Trials (RCT) are considered the "gold standard" of primary intervention studies, whilst meta analysis - an aggregation of primary studies - are even higher forms of evidence. Adriyani et al's intervention ranks lower than an RCT in the evidence based practice pyramid, however, clinically relevant conclusions can still be drawn from this study.

Study Summary
Participant Pool:

22 Indonesian males (n= 6) and females (n=6) who met the inclusion and exclusion criteria.

The Exercise Program:

10 week HIIT treadmill program with 3 x 33 minute sessions a week, which included:

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 * A 10 minute warm up at <64% Max HR (MHR)
 * 3 x 4 minute work intervals at 77-95% MHR
 * 3 minute interspersed active rest intervals at 64-76% MHR
 * A 5 minute self paced cool down.

The Data:
 * Pre-participation screening involved a health evaluation to assess inclusion criteria, exercise contraindication questionnaire and a resting ECG.
 * Reported measurements include: digitally recorded BP, Bioelectrical Impedence scanning of body composition, digital heart rate (HR) monitoring and waist circumference
 * Parametric tests or non-parametric tests were used based on the distribution of data.

Assessment of Methodology
Limitations:


 * Lack of quantitative evidence around methods: max HR calculations, contraindication assessments and adjustment time between work and rest periods.
 * Intervention Scope: No measurement of external physical activity and short program duration limits visible body composition changes.
 * Measures: Bioelectrical Impedence scanning results are heavily influenced by variable testing conditions, such as recent exercise and fluid/food consumption.
 * Hypertension criteria ranges differ from ACSM guidelines . This is likely reflective of the cultural demographic.

Advantages:
 * Participant criteria targets hypertensive populations whilst limiting comorbidity and lifestyle factors which may introduce outlying data.
 * Clinical assessments seem to have been conducted in a standardised, best practice manner.
 * Provides sparsely researched gender specific insights into training modalities for clinical populations.

What were the basic results?
Adriyani et al were modest in the appraisal of their interventions outcomes, correlating their findings with potential physiological justification. They reported:
 * A smaller reduction of BP in women than men may be attributed to greater decreases in peripheral resistance in men.
 * Greater reduction of fat and waist measures in men may be related to post exercise energy expenditure and greater use of fatty acid oxidation in HIIT caused by the large degree of muscle mass, metabolism and contractility among male populations.
 * Increased skeletal muscle mass and fat free mass among women was thought to be associated with high levels of daily activity compared to men.

What conclusions can we take from this research?
This study concludes that HIIT is a viable exercise modality for the prevention and treatment of hypertension, particularly in men. However, moderate intensity aerobic and resistance exercises can be sustained for longer volumes of time, which translates to a higher energy expenditure as well as increased mobilisation and consumption of fats in both obese males and female populations.

Adriyani et al highlights that the only other known study comparing HIIT among hypertensive males and females showed greater BP decreases in women than men, however, the referenced intervention was conducted among elderly populations over a 6 month period with near aerobic activities. A systematic review comparing HIIT and Moderate Intensity Continuous Training (MICT) interventions between 4-6 weeks long found that both yielded comparable reductions in BP measurements, while HIIT had greater improvements to cardiovascular adaptations (VO2 Max).

Practical advice
Recommendations for Exercise:


 * If SBP or DBP is greater than 200 or 115 mmHg prior to exercise, do not exercise and consult your doctor immediately
 * Measure exercise with perceived exertion scales in place of HR measures if you're on medication that influence HR such as beta-blockers
 * Start with short periods of moderate intensity continuous aerobic exercise (10-15 minutes) every second or third day, such as stationary cycling or rowing, if you were previously inactive. Add 5 minutes to each session per week to achieve 30 minutes of exercise on most days.
 * Focus on cool down and hydration, as hypertension medications may cause sudden blood pressure drops or dehydration.
 * Consider creating weekly music playlists and add HIIT, resistance or flexibility sessions over time to encourage engagement and meet the Hypertensive Physical Activity Guidelines

Further information/resources
For those who may be experiencing hypertension, seek medical advise and see below for more information:

- Hypertension Symptoms

- Heart Foundation Clinical Information and Help Lines

- Social Media Support Groups

Or see here for Academic Literature