How are calories burnt when performing a bicycle crunch?

Patient: Hi, when performing a bicycle crunch are more calories burnt if the legs are extended and bought down as low & close as possible to the floor, compared to being extended and raised higher off the floor. Also, does extending and bringing the legs as close/ low to the floor help build more muscle in the legs, and is it the legs being extended and bought down as close to the floor as possible that is the toughest & best way for performing a bicycle crunch compared to the legs being extended and raised higher from the ground. Finally, does the leg and knee have to be crunched up to the 90 degree level to start burning calories or are calories burnt the moment the leg and knee is crunched up from the extended/ straightened position. And, are the same amount of calories burnt as soon as the leg and knee starts crunching up/ contracting from the extended/ straightened position, compared to the leg & knee being crunched up all the way to the 90 degree level and beyond. Do small contractions of the leg and knee that are not contracted and not bought very high/ close to chest level burn the same amount as big longer contractions that are higher & closer to the chest. Thankyou for you help and kind regards,Kelly.

Doctor: Hello,Thank you for posting your query at AskTheDoctor.comI am glad to assist you.When you are doing the bicycle crunch the recommended way of doing it is by putting the hands behind the head, and bring in the knee towards the chest while lifting the shoulders off the ground.The legs being extended and being raised higher from the ground is the toughest & best way for performing a bicycle crunch. This will ensure good leg muscles and also help the abdominal muscles contract as far as it can.Calories start burning the moment the leg is off the ground and as you keep increasing the repetitions. Try to straighten the leg out to a 45- degree angle while turning the upper body to the other side, this ensures maximum contraction and keep repeating the same throughout the workout.The smaller contractions do not burn the same calories, as the finer details need to be perfected in order to lose weight. You should ideally try to perfect the process and do a minimum of 15-20 repetitions for 3-4 sets with 30 seconds break in between. Once the body gets used to it, keep increasing the count. This ensures you keep losing adequate calories.I will be glad to assist you further,Regards