Caffeine-Augmented Sprint Interval Training Outcomes in Obese Women: An Examination by Inter-Individual Analysis on Physical and Physiological Adaptive Responses

Xinying Zhao¹Yang Liu^2*

• ¹Xi'an Peihua University, Xi'An, China
• ²Shenzhen Technology University, Shenzhen, China

Background: The objective of the present study was to elucidate the impact of a 12-week caffeine consumption before sprint interval training on the physical and physiological adaptations in obese women. Methods: Thirty overweight and obese women volunteered and were randomly divided into three groups: Caffeine (3 mg·kg⁻¹ body mass, n = 10), Placebo (3 mg·kg⁻¹ body mass in cellulose, n = 10), and Control (n = 10). Over 12 weeks, subjects in the Caffeine and Placebo groups consumed their supplements three times per week, ~60 minutes before each sprint interval training session. Fat mass, lower body strength, and cardiorespiratory fitness were evaluated at baseline and after the intervention. Fasting glucose, lipid profiles, and adipokines (leptin, adiponectin, and irisin) were measured 48 hours before and after the intervention. Results: Both the Caffeine and Placebo groups exhibited significant improvements (p < 0.05) in these variables after 12 weeks of training. The Caffeine group showed significantly greater adaptive responses (p < 0.05) than the Placebo group in reducing fat mass (SMD = -0.27), enhancing strength (SMD = 0.30) and cardiorespiratory fitness (SMD = 0.43), and altering fasting glucose (SMD = -0.74), leptin (SMD = -0.23), adiponectin (SMD = 0.18), and irisin (SMD = 0.42) after the intervention. Conclusions: Supplementation of 3 mg·kg -1 body mass caffeine before sprint interval training resulted in greater reductions in fat mass and improvements in strength and cardiorespiratory fitness, as well as more pronounced changes in fasting glucose and adipokines among overweight and obese women.