An Analysis of Factors That Cause Overtraining in Elite Swimmers in Response to Resistance Training
Take Home Points to Avoid Overtraining in Swimmers
Background on Overtraining in Elite Swimmers
Swimmers most readily take part in a concurrent training program, performing both resistance and endurance training. For most of the year, training takes place six days a week with a frequency of one to three times per day for a duration of one to three hours each. The volume of training depends on an individual’s race specialty. Sprinters, defined by those who’s best events include the 50 freestyle and the 100 of any stroke, usually perform two to six thousand yards per practice. Middle-distance swimmers are those who’s best events include the 100 and 200 of any stroke and both the 200 and 400 individual medleys. They usually perform five to seven thousand yards per practice. Distance swimmers are those who’s best events include the 500 and mile freestyle. They usually perform seven to nine thousand yards per practice. While these volumes are measured per practice, it does not account for the training that takes place outside of the pool. Swimmers also perform resistance training sessions and core work exercises. These may be done in a regular training cycle with individual loads or they may be done in circuit training, or most readily known as high intensity interval training which combines longer workouts with higher intensity resistance exercises. Lastly, swimmers undergo a period of taper prior to competition. This is a period of low volume and moderate intensity training that is intended to allow the swimmer to recover from the season while maintaining their training adaptations in preparation for peak performance.
Another measure of inflammation is neutrophil count, which are white blood cells that flock to areas of inflammation. In a study by Hooper et al. (1995), they found that neutrophil levels were shown to be higher in overtrained swimmers during taper, but not different from well trained swimmers at any other point in the season. These studies suggest that high intensity resistance training could be a strong factor in overtraining in swimmers in regards to inflammation and a prolonged effect could lead to performance decrements if the resistance training program is not discontinued with enough time to recover prior to competition.
Other markers that have commonly been used to diagnose overtraining are creatine kinase, nutrition, and infections. A common enzyme that aids in the production of energy is creaking kinase (CK). It is involved in the breakdown of phosphocreatine in short bouts of high intensity exercise seen in resistance training. Elevated levels of creatine kinase is a sign of muscular distress and inhibits muscle contraction due to their effect on decreasing the cell’s pH (20). Creatine kinase has been shown to be a good indicator of cellular damage in swimmers, as creatine kinase levels increased with high volumes of training and returned to baseline after recovery (7). Prolonged elevation in creatine kinase could indicate overtraining in swimmers as a result of resistance training.
Overtraining has also shown to be an effect of malnutrition. As stated above, swim workouts can range anywhere from one to three hours. Most swimmers consume water or gatorade during this time in order to stay hydrated. However, for durations of exercise over an hour, protein must be consumed during exercise in order to elicit a favorable fractional synthetic rate. Fractional synthetic rate (FSR) is the rate of muscle protein synthesis over muscle protein breakdown. An FSR greater than one is favorable and means there is more protein synthesis than breakdown and the opposite if it is lower than one. Studies indicate that ingesting carbohydrates only and waiting to consume protein until after training results in fractional synthetic rates less than one, suggesting more protein breakdown (4, 12). Only subjects who consumed protein during workout experienced fractional synthetic rates greater than one, suggesting more protein synthesis (12). Thus, overtraining could be the result of greater muscle protein breakdown in swimmers. However, muscle protein synthesis is also correlated with the testosterone:cortisol ratio as mentioned previously in this article. Since overtraining due to high intensity resistance training favors muscle protein breakdown in regards to hormones, it is even more important to ingest protein during exercise to elicit favorable rates in muscle protein synthesis and avoid overtraining.
Lastly, upper respiratory tract infection (URTI) is an illness caused by infection of the upper respiratory tract, such as the mouth, nose, throat, and lungs. High intensities and high volumes of training can inhibit immune function of protecting against these infections (15). Immunoglobulin A (IgA) is a common antibody that defends against these infections and research indicates a significant decrease in IgA concentrations in overtrained compared to well-trained swimmers suggesting an immune system deficiency in overtrained swimmers (15). High intensity resistance training puts high levels of stress on the body and could result in decreased immune function.
Ultimately, overtraining is most readily defined as a lack of performance despite consistent training. Though we have seen that combining resistance and endurance training improves middle-distance swimming performance, adding resistance training in excess is the cause of overtraining. This is because exhaustion seen as a result of endurance training is obvious, while serum cortisol, testosterone levels, inflammation, and other markers mentioned in this article are not frequently measured or taken into account when developing training plans. Resistance training puts greater stress on individual muscle fibers and adding high intensity resistance training along with training performed in the pool can amplify the factors of overtraining, resulting in performance decrements in swimmers.
For endurance athletes, a commonly used predictor of performance is maximal aerobic speed (MAS) and velocity at aerobic threshold (VAT). Greater maximal aerobic speed and velocity at aerobic threshold are favorable. Overtrained athletes normally see a decrease in speed at high percentages of MAS (3). Research indicates that overtrained swimmers who experienced increases in cortisol, decreases in testosterone, and elevated creatine kinase levels from resistance training saw decreases in speed at high percentages of their maximal aerobic speed, suggesting they were overtrained as a result of high intensity resistance training (23). However, these results were gender specific. Research also indicates that female swimmers display a greater ability to adapt to training volumes and intensities in regards to performance, suggesting women posses a greater ability to recover from training than men (1, 23). This could be the result of lower loads of resistance training performed by women due to different muscle fiber types and smaller muscle mass. Thus, resistance training could be a large factor of overtraining in swimmers and training plans should be gender specific in order to maximize performance.
Many physiological factors have been found in swimmers experiencing overtraining, including decreased ability to fight infections, higher levels of stress and cortisol, lower levels of testosterone, prolonged inflammation of muscle tissue, and insufficient intake of protein during training to elicit proper recovery. Though, some of these factors cannot be easily observed and are not frequently measured, it is important for coaches and parents to pay attention to their swimmers in order to help them achieve high levels of performance. Frequency, intensity, and volume of both resistance and endurance training should be carefully managed, and input from the swimmer in developing training plans is required in order to maximize performance and avoid becoming overtrained.
A special thanks goes to Tannah Broman and the Arizona State University library staff for all their help.
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- Photo of Michael Phelps retrieved from phttp://www.chasethewhiteline.info/swimming/injuries-that-face-swimmers/.
- Other photos taken by Dan Kesler and Taylor Wohrley
Written by Grant Smith swam with Swim Atlanta in Roswell, GA for most of his life and then decided to continue his education and swim at Arizona State University. After a year of swimming, he decided to focus on school and his dream of attending graduate school to receive his Doctorate in Physical Therapy. He is currently coaching at Scottsdale Aquatic Club while he pursue’s a Bachelor’s in Kinesiology and is graduating in May.