A 1964 French decree reserves the word 'surgelé' (deep-frozen) for food chilled very quickly to its core, down to -18 °C (0 °F), then kept there until sale. Speed is everything: rapid freezing forms tiny ice crystals, while slow freezing, as in a home freezer, grows large crystals that tear cells apart. Once thawed, the food then leaks more water and turns mushy.
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.