I have exercised and jogged regularly, trouble-free for decades.   About 6 weeks ago very sudden stiffness (nearly cramps) started in the lower part of my legs (between ankles and calves and more on the 'outside' of my legs than centrally). This feeling spreads into my calves.  The feeling moves into my hamstrings.  Then into my quads/thighs.  And sometimes into my groin (left side mainly in all cases).  It can be in two places at once.  My diet had not changed.  It has now: more water and hydrates, etc.  But the stiffness, near-cramp symptoms continue in all the major muscles groups in my legs.  Slowly I plough on and complete 2-mile jogs but only 1-2 times per week. Walking normally, no problem.  But the slightest increase in effort, such as walking up a steep hill, and the stiffness starts, fast.  Also, for the past few months I've noticed that my thighs seem under 'tension' when I wake up, and throughout the day.  As though they never fully relax.  Like a TV being on stand-by, rather than being turned off.  If this is the case it means my thigh muscles (and probably the rest of the muscles in my legs) are always 'at work' though the level of effort 'at rest' causes no additional strain. Internet research about muscle stiffness/cramps leads one to read about every dreadful life-threatening ailment known to man when one's own specific symptoms can't be found. Key words: muscle cramp, muscle stiffness, cramps.  Can anyone shed light on this?