Martha is trying to figure out what type of exercise will help her lose the most weight. She decides to spend the summer figuring it out. She weighs herself and begins walking on a treadmill for 30 minutes 6 days per week at 2.8-3 miles per hour. She plans to use this method for 4 weeks. After the end of 4 weeks she weighs herself and found that she has lost 6 pounds. For the next 4 weeks Martha decides she will now try cycling. She will ride her bike for 30 minutes 6 days per week. She plans to ride 3 miles each day. After the 4 weeks Martha finds that she has lost a total of 11 pounds. For the last 4 weeks Martha decides to take an aerobics class 3 times per week. The classes are 1 hour in length. At the end of that 4 week period she finds that she has lost a total of 20 pounds.Which intervention appears to have been the least effective