You're asking a great question about calorie expenditure! According to the U.S.-based Cleveland Clinic, the more intense an activity, the higher your metabolic equivalent of task (MET) and, consequently, the greater your calorie burn. Exercise physiologist Ben Kuharik notes that any physical activity burns calories, but some are more efficient at boosting your metabolism.

Here's a breakdown of the top calorie-burning workouts based on a 150-pound person exercising for one hour, as provided by the Cleveland Clinic:

Running: This full-body workout can burn a significant number of calories depending on your pace:

Jogging: Approximately 476 calories per hour.

Running at 5 mph: 544 calories per hour.

Running at 6 mph: 680 calories per hour.

Running at 10 mph: Up to 1,088 calories in just an hour.
Running engages your legs, core, and upper body, with higher speeds or inclines demanding more energy expenditure.

Jumping Rope: Described as "high-intensity, high-reward," jumping rope is a very efficient calorie burner:

Slow pace: Around 544 calories per hour.

Fast pace: Up to 816 calories per hour.
Kuharik recommends it for short, intense cardio bursts or as a workout finisher for quick results.

Swimming: This low-impact, total-body workout offers good calorie burn with the added benefit of being gentle on joints:

Casual pace: About 476 calories per hour.

Vigorous swimming: Can increase to 680 calories per hour.
The natural resistance of water strengthens muscles and reduces joint stress.

Cycling: Another joint-friendly cardio option, cycling's calorie expenditure varies greatly with intensity and environment:

Leisurely pace (around 5.5 mph): Roughly 272 calories per hour.

Moderate pace (12–13 mph): Around 544 calories per hour.

Faster pace (16–19 mph): Up to 816 calories per hour.
Kuharik points out its effectiveness, especially when cycling outdoors.

Walking: While lower in intensity, walking is a valuable exercise, particularly for beginners:

Walking at 3 mph: About 224 calories per hour.

Brisk walk at 4 mph: Can increase to 340 calories per hour.
Kuharik emphasizes that walking is a great way to build an exercise habit and contributes to overall calorie output, even if it's less intense than other activities. It's important to note that calorie burn for walking can vary based on individual factors like weight, sex, and ethnicity, as mentioned by Healthline.

In summary, running at 10 mph appears to torch the most calories in an hour, reaching up to 1,088, among the activities listed for a 150-pound person. However, the intensity at which each activity is performed significantly impacts the total calories burned.