fitness and fat oxidation in overweight chinese, indian and malay men

Conditions: Overweight and Obesity

Summary: south asian men have lower cardiorespiratory fitness (crf) than white men which is associated with a reduced capacity to oxidise fat during exercise. this is a risk factor for weight gain/regain. whilst comparisons with europeans are valuable, asians are not a homogenous group and substantial differences in obesity and body fat partitioning exist with ethnicity. this cross-sectional pilot investigation aims to compare crf and fat oxidation at rest and during exercise in chinese, indian and malay men (from singapore) with elevated bmi (23 -30 kg/m2). forty-five men (15 each ethnicity) with elevated body mass index (23 -30 kg/m2) will complete testing in a fasted state on two separate mornings separated by ≥72 hours: (i) for a measure of crf; and (ii) for a measure of fat oxidation at rest and during incremental exercise.

south asian men have lower cardiorespiratory fitness (crf) than white men which is associated with a reduced capacity to oxidise fat during exercise. this is a risk factor for weight gain/regain. whilst comparisons with europeans are valuable, asians are not a homogenous group and substantial differences in obesity and body fat partitioning exist with ethnicity. this cross-sectional pilot investigation aims to compare crf and fat oxidation at rest and during exercise in chinese, indian and malay men (from singapore) with elevated bmi (23 -30 kg/m2). forty-five men (15 each ethnicity) with elevated body mass index (23 -30 kg/m2) will complete testing in a fasted state on two separate mornings separated by ≥72 hours: (i) for a measure of crf; and (ii) for a measure of fat oxidation at rest and during incremental exercise. a submaximal exercise test will be used to estimate crf (maximum oxygen uptake, vo2max) during walking using a standard protocol where subjects walk on a treadmill at 5 km/h with regular increments in gradient until individuals reach 80% of their estimated maximum heart rate \[220 - age (years)\]. perceived exertion will be monitored assessed periodically during the test and expired gases continuously measured via a mouthpiece attached to an automated metabolic cart (parvomedics mms-2400; parvomedics, sandy, ut). oxygen consumption will be extrapolated to estimate vo2max based on estimated maximum heart rate. resting fat oxidation will be determined via a 30 minute measure of expired gases under a ventilated hood attached to an automated metabolic cart. fat oxidation during exercise will be determined via walking on a treadmill with increments in speed and gradient until the respiratory exchange ratio is ≥ 0.95. primary outcomes will be compared among groups and adjusted for any covariates (e.g., bmi, body fat percentage) as necessary.

Eligibility criteria:
inclusion criteria: * male * age 25 - \<45 years * chinese, indian or malay based on self-identity for three generations (parents and grandparents) * bmi ≥ 23 - \< 30 kg/m2 and/or waist circumference ≥ 90 cm * physically inactive defined as \< 150 minutes moderate or \< 75 minutes vigorous leisure-time physical activity per week, or the equivalent combination of both exclusion criteria: * females * personal history of cardio-metabolic diseases * dieting (i.e. restricting food/energy intake) * smokers * consuming alcohol \> 3 times per week with \> 3 drinks per time * using any medications which affect carbohydrate or lipid metabolism * any lower body injuries * fasting blood glucose \> 6.1 mmol/l