Overtraining is a danger for any motivated distance runner. In striving to improve your performance, you progressively increase the volume and intensity of your training. When races go well, the positive reinforcement spurs you to train harder. When races go poorly, you figure you aren’t fit enough, and train even harder. At some point, you hit your individual training threshold. This is the amount of training stress above which you start to break down.
Individual training thresholds vary greatly between runners. Jerry Lawson trained comfortably at 140 miles per week, while some runners cannot maintain 40 miles per week. Similarly, some runners can handle 2-3 hard days of training in succession, while others need 2-3 easy days after each hard workout. Your individual training threshold also changes with time. Jerry couldn’t always handle such big mileage, but increased his mileage as his capacity to withstand the strain increased.
It is important to clarify what overtraining is and isn’t. Fatigue for a day or 2 after a hard training session isn’t overtraining. In fact, it is a necessary step in the recovery and development process. When training stress is applied in the appropriate dosage, then you improve at the optimal rate. If your training stress is above the optimal level, you may still improve, but at a slower rate. Only above a higher threshold (your individual training threshold) does true overtraining occur. The zone between optimal training for improvement and the point at which performance decreases is termed “overreaching.” This zone is where many runners spend much of their time.
Overreaching occurs when you string together too many days of hard training. Your muscle fatigue is most likely due to glycogen (carbohydrate) depletion, and you simply need time for metabolic recovery. A few days of moderate training combined with a high carbohydrate diet should quickly remedy the situation. Overreaching can also be caused by dehydration, a lack of sleep, or the addition of other life stresses on top of your normal training. In all these cases, your body should rebound quickly when the extra stress is removed.
Repeated overreaching eventually leads to overtraining syndrome, which is thought to be regulated by the hypothalamus. Located at the base of the brain, the hypothalamus controls body temperature, sugar and fat metabolism, and the release of a variety of hormones, and is essentially your master control center for dealing with stress. When your hypothalamus cannot handle the combination of training and other stresses in your life, the result is overtraining syndrome. The symptoms are fatigue, decreased motivation, irritability, and poor athletic performance.
In the July, 1998 issue of Medicine and Science in Sports & Exercise, Carl Foster, Ph.D., presents a new technique to help athletes detect and avoid overtraining. The technique is based in part on evidence that horses progress following a hard-easy training program, but become overtrained when the workload on the easy days is increased. The hypothesis is that overtraining is related to both the difficulty of training (the training load) and the “monotony” of training. To assess the former, an athlete rates the difficulty of a training session on a scale of 1-10, and then multiplies this number by the total number of minutes of the training session. Monotony of training is the variation (or lack thereof) in the difficulty of training from day-to-day. Monotonous training typically consists of one moderately hard day after another, whereas varied training consists of a mix of hard days, easy days, and the occasional rest day.
Training strain is the combined effect of the training load and the training monotony. Dr. Foster has found that training strain can predict overtraining-related illness and injury. In a study with 25 endurance trained athletes, 84% of illnesses were preceded by an increase in training load above the athlete’s individual training threshold, while 77% of illnesses were preceded by an increase in training monotony. Training load and training monotony combined (training strain) explained 89% of illnesses among these athletes. Almost half of the peaks in training above these athletes’ individual strain thresholds resulted in illness.
These results suggest not only that training load is a useful predictor of overtraining-related illness, but that training monotony is also a contributing factor. This is the best evidence to date that mixing easy recovery days into your training program is necessary for optimal improvement without breaking down.
The 2 tables below present sample weeks with the same training load. Training schedule A is an example of a low monotony week. There are 3 days with a training load >500 (hard days = Tuesday, Wednesday, and Sunday), 1 day between 300 and 500 (moderate day = Friday), and 3 days <300 (easy days = Monday, Thursday, and Saturday). Following this schedule, you would get in high quality training with adequate recovery and could expect your fitness to steadily improve.
Total Load: 2,975
Training schedule B is an example of a high monotony week. There is 1 day > 500 (hard day = Sunday), and the other 6 days are between 300 and 500. Following this schedule, you would be training fairly hard all the time, and would never feel particularly fresh for your next workout. Foster’s results suggest that continued training in this way would be more likely to lead to overtraining syndrome than if you followed training schedule A. Training schedule B would also lead to a slower rate of improvement than training schedule A.
Try recording your training this way for several months and see if you can detect your individual strain threshold. If you can find the combination of training load and monotony that puts you over the edge, then you can keep your training strain below that threshold for optimal training and optimal performance.
Total Load: 2,975
(This column originally appeared in Running Times Magazine.)