| Contrary to popular belief, women aren't the | | | | |
| only ones with biological clocks. We all have | | | | Don't Fix It If It's Not Broken |
| them, and heed their ticking on a daily | | | | |
| basis. If you are a regular exerciser, you | | | | First of all, don't change your schedule if |
| may have already determined your most | | | | you feel good beginning your day with |
| productive time to exercise and follow a | | | | exercise. Everyone agrees that exercise at |
| routine that works best for you. On the other | | | | any time is better than no exercise at all. |
| hand, if your exercise time varies from day | | | | In fact, people who exercise in the morning |
| to day, and it's wearing you out instead of | | | | are more successful at making it a habit. And |
| pumping you up, you may be interested in the | | | | though it has been suggested that morning |
| work of scientists who are studying the | | | | exercise may put some people at higher risk |
| proverbial internal clock and how to best | | | | for heart attack, further research indicates |
| determine what time of day you should | | | | that there is simply a generalized increased |
| schedule your workouts. | | | | risk of heart attacks in the morning. If your |
| | | | schedule favors an early workout, emphasize |
| Rhythm: It's Not Just For Dancing | | | | stretching and a good warm-up to insure that |
| | | | your body is ready for action. |
| The secret appears to lie in circadian | | | | |
| rhythms, the daily cycles that our bodies | | | | Other Considerations |
| follow. These rhythms originate in the | | | | |
| hypothalamus and regulate everything from | | | | If stress relief is your goal, exercise |
| body temperature and metabolism to blood | | | | always works, all the time. And if you're |
| pressure. The rhythms result from the firing | | | | wondering when it's best to train for an |
| rate of neurons. They have conformed to our | | | | upcoming event, it all depends on what time |
| 24-hour light-to-dark cycle, and may be | | | | you'll actually be competing. If an upcoming |
| regulated and reregulated each day according | | | | marathon begins at 7:00 a.m., try training at |
| to the environment. | | | | that time of day. Though training at any time |
| | | | of day will raise performance levels, |
| Warm Is Better | | | | research has shown that the ability to |
| | | | maintain sustained exercise is adaptive to |
| It is the influence of circadian rhythms on | | | | circadian rhythms. In other words, |
| body temperature that seems to yield the most | | | | consistently training in the morning will |
| control over the quality of a workout. When | | | | allow you to sustain exercise during a |
| body temperature is at its highest, your | | | | morning marathon longer than if you train in |
| workouts will likely be more productive; when | | | | the evening. |
| your temperature is low, chances are your | | | | |
| exercise session may be less than optimal. | | | | Find Your Peak |
| Body temperature is at its lowest about one | | | | |
| to three hours before most of us wake up in | | | | To determine your own circadian peak in body |
| the morning, in contrast to late afternoon | | | | temperature, record your temperature every |
| when body temperature reaches its peak. (To | | | | couple of hours for five to six consecutive |
| determine your own circadian peak, refer to | | | | days. Body temperature usually fluctuates by |
| the box to the right.) Studies have | | | | plus or minus 1.5 degrees throughout the day. |
| consistently shown that exercise during these | | | | Try exercising during the period three hours |
| late-in-the-day hours produces better | | | | before and after your highest temperature. If |
| performance and more power. Muscles are warm | | | | you are an early bird or a night owl, you may |
| and more flexible, perceived exertion is low, | | | | notice that your temperature peaks one to two |
| reaction time is quicker, strength is at its | | | | hours before or after the norm (between 4 |
| peak, and resting heart rate and blood | | | | p.m. and 6 p.m.); you can adjust your |
| pressure are low. | | | | exercise time accordingly. |