Additive effects of caffeine and cold water during submaximal leg exercise

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry

Background:

• Cold water immersion is known to affect metabolic and physiological responses during exercise.
• Caffeine is a common ergogenic aid used to enhance athletic performance.

Purpose of the Study:

• To investigate the additive effects of cold water immersion and caffeine (CF) ingestion on energy production and core temperature during exercise.
• To determine if combining cold water and caffeine provides physiological benefits beyond individual effects.

Main Methods:

• Ten male participants exercised for 55 minutes at 1.5 W.kg-1 in both 28°C and 18°C water.
• Two trials were conducted at each water temperature: one with CF (5 mg.kg-1) and one with a placebo (PL).
• Measurements included free fatty acids (FFA), glycerol, lactate, VO2, minute ventilation (VE), heart rate (HR), respiratory exchange ratio (RER), and rectal temperature.

Main Results:

• Cold water alone decreased FFA and glycerol, while increasing lactate, VO2, and VE.
• Caffeine alone increased FFA, glycerol, lactate, VO2, VE, HR, and rectal temperature.
• Combined cold water and CF showed additive effects on FFA, glycerol, lactate, VO2, and VE, but not RER or rectal temperature.

Conclusions:

• The combination of cold water and caffeine alters substrate availability and increases energy production during exercise.
• Despite increased energy production, the combined intervention does not enhance lipid utilization or affect core body temperature.
• The use of caffeine during exercise in cold water offers no discernible physiological benefit.