According to the European Food Safety Authority, healthy adults can have up to 400 mg of caffeine a day safely, or 200 mg during pregnancy. A cup of filter coffee holds about 90 mg, a can of energy drink about 80 mg. Remember to add up tea, cola and chocolate. Palpitations and jitters are signs you've overdone it.
Chlorine on its own is fairly gentle. But when it combines with urine, sweat and other grime from swimmers, it forms chloramines, which cause stinging eyes and that classic 'chlorine smell'. A well-kept pool barely smells at all. Shower before you swim and never pee in the water.
Muscle mass slowly shrinks with age, putting independence at risk. But in 1990, a study had nursing home residents aged 86 to 96 train their legs for eight weeks: their strength more than doubled. Muscle responds to training at any age. Getting up from a chair without using your hands is already an exercise.