In 1929, A. V. Hill conducted a series of experiments with frogs that led him to conclude that lactic acid accumulation is the primary cause of failure in muscle tissue. Today, the role of lactic acid in muscle fatigue is still a hotly debated topic. Which of the following arguments pose a credible challenge to A. V. Hill's conclusions about the effect of lactic acid on muscle fatigue?
More recent experiments demonstrate that the Hill effect does not occur at human body temperatures (37°C).