There is abundant evidence of a time-of-day effect on performance in strength and power sports—performance is significantly enhanced later in the day compared to in the morning. The effect is thought to be due to variations in body temperature, hormone concentrations, muscle contraction ability, and even the ability of the muscles to remove waste products like lactic acid. However, a recent study found that it’s possible to improve strength and power performance by drinking caffeinated coffee.
This study used elite athletes and had them perform three trials in which maximal squat and bench press strength and power were measured. The first trial was in the morning at 10 a.m. and the athletes received 3 mg/kg/bw of caffeine; the second trial was in the morning at 10 a.m. and they received a placebo; and the third trial was in the evening at 6 p.m. and they received a placebo.
Results showed that the extra kick of caffeine enhanced maximal strength and power performance in the bench press and squat by 3 to 6 percent over the morning placebo trial. In fact, strength and power were nearly equal to levels recorded in the evening trial when performance peaked.
The reason for enhanced performance from caffeine is thought to be that it acts directly on the muscles to produce greater strength and power output. There was a significant increase in norepinephrine concentration in the morning caffeine trial that was equal to the evening trial.
Researchers suggest that the increase in norepinephrine stimulated sympathetic muscle activity for greater performance. In simple terms this means caffeine increases muscle strength and power through an effect directly in the muscle rather than acting on the central nervous system.
The take away is that caffeine is a potent performance enhancer for morning competitions and training. A fairly large dose of caffeine is necessary—225 mg of caffeine for someone weighing 75 kg based on the 3 mg/kg amount tested here, which equals about 2.5 espressos.