<span>Heart Rate Reserve, HRR. Heart rate reserve (HRR) is the difference between resting heart rate (HR<span>rest) and maximum heart rate</span> (HRmax). Heart rate reserve is used when determining exercise heart rates. The Karvonen formula is used to calculate exercise heart rate at a given percentage training intensity.</span>
Answer: spells out the terms for success, and knowing exactly what you want to accomplish goes a long way.
Explanation:
B) Vaginal
Vaginal is always the best option, all these others have a higher risk of damage to the internal glands.
Strength, stamina, and speed might be 3 good areas to focus on.