Which condition can lead to excessive strain in a horse's muscles?

Inadequate warm-up before exercise is a critical factor that can lead to excessive strain in a horse's muscles. Warm-up activities are essential as they help to gradually increase the horse's heart rate, improve blood flow to the muscles, and prepare the musculoskeletal system for the physical demands of exercise. Without an adequate warm-up, the muscles may not be sufficiently prepared for activity, increasing the risk of strains, injuries, or muscle soreness.

In contrast, excessive rest periods can impact a horse's overall fitness, but they do not directly cause strain during exercise. Regular stretching routines, when done appropriately, can help maintain flexibility and reduce the risk of injury, while a balanced diet provides the necessary nutrition for maintaining muscle health and overall performance in horses. However, these factors do not directly relate to the immediate risks associated with insufficient warm-up activities.