Q During recent running I found that I lacked energy, and even though my heart rate was sky-high, I seemed to be plodding around every run. I went to my GP, and he diagnosed an underactive thyroid and prescribed Thyroxine. After a month, however

. Circadian rhythms of heart rate, respiration and oxygen consumption increase during normal waking hours, and our heart rate is about 20 per cent higher at noon than it is at midnight (even if you sleep at noon). Injury risksTriathletes are also more likely

decreases, so your heart has to pump less blood faster to keep you cool, making you heat up more and making your heart beat even faster."The hours of training you put in make your body better at transporting oxygen to your muslces, so you stay below your

't running long distances, you could still be at risk of overtraining. If you're super-busy at work, stressed or having relationship problems, it can impact upon your training and trigger UPS.What are the symptoms?Elevated resting heart rate Overtraining can

between 50 and 70 per cent of your maximum heart rate. When you exercise at this low intensity, your body draws energy from fat. As your heart rate goes up, more energy comes from carbs. So it seems logical that to lose fat you should keep your heart

? In addition to keeping your heart rate at or below 140 bpm, experts advise you to train outdoors, rather than indoors on a treadmill where the wind’s cooling effect is eliminated. If you are inside, be sure the area is well ventilated; keep the windows

to exercise only at 140 bpm heart rate or below, for example, may be over-cautious for many athletes.If you're having an uncomplicated pregnancy and you were already running beforehand, then as long as everything is progressing as it should be and your doctor

soreness), don't work out. "Running with a fever can make the illness worse and there's a risk of passing the virus to the heart," Nieman says. Sip hot liquidsA study found that people who drank hot beverages rated cold symptoms as less severe than those

50 and 70 per cent of your maximum heart rate. When you exercise at this low intensity, your body draws energy from fat. As your heart rate goes up, more energy comes from carbs. So it seems logical that to lose fat you should keep your heart rate low

. The last physiological variable to adapt is your sweat rate, which takes eight to 14 days to reach maximum efficiency. Other, faster responders include increased plasma volume, decreased sodium concentration in the blood, decreased heart rate while running