Q: What is the best way to balance overload and recovery to help provide gains in fitness and performance?
A: One major challenge for those seeking to improve fitness or prepare for competition is determining the optimal level of training to promote improvements while avoiding injury or decreases in performance. Adaptation is a basic principle that highlights the requirement for a sufficient and regular training stimulus to bring about a desired physiological change (2). A sufficient stimulus must be above the training threshold (or minimum level required), and this level of training provides for “overload.” For example, overload in aerobic conditioning might involve increases in intensity or frequency; overload in muscular conditioning might involve increases in resistance or the number of sets or repetitions. Although overload is required for improvement, concerns arise when excessive overload is combined with inadequate recovery (6).
Unfortunately, injuries do occur. In the United States, sports and exercise account for approximately 18% of reported injuries, and leisure activities (excluding sports) account for approximately 23% of reported injuries (3). In 2014, the National Electronic Injury Surveillance System noted 62,700 injuries in emergency departments coded as “exercise equipment” (note that this does not include swimming pools, weights, bicycles, and various sporting equipment such as balls and rackets) (8). Of that total, the number of injuries associated with treadmills was the highest (24,400 in 2014) (8). To minimize the chance of acute injury, become familiar with the equipment and be sure to use the equipment in the manner intended. The American College of Sports Medicine (ACSM) has made available a number of full-color downloadable brochures with practical information on selecting and effectively using various types of exercise equipment (e.g.. free weights, home weight machines, medicine balls, resistance bands, stability balls, treadmills, stationary bikes, elliptical trainers, stair climbers) at http://acsm.org/access-public-information/brochures-fact-sheets/brochures.
Unlike acute injuries, overuse injuries result when the intensity of exercise is maintained at a high level for an extended period without adequate rest (2). The right amount of training must be individualized, taking into account overall training load and other variables, including nutrition and rest (2). When training intensity is not balanced with adequate recovery, needed cellular repair may be hampered (4). Subclinical tissue damage may occur even before pain or other symptoms are reported (4). Overuse injuries of tendons include collagen fiber degeneration and a hampered healing response (unlike acute injuries that are inflammatory in nature) (4). Slow recovery along with required modifications in activity and rest are typical in these situations. For runners and endurance athletes, overuse injuries may include patellofemoral pain syndrome, iliotibial band friction syndrome, medial tibial stress syndrome, Achilles tendinopathy, plantar fasciitis, and stress fractures (4). A classic study (7) examining the impact of training load on aerobic fitness and injury is included in Box 1.
CLASSIC STUDY EXAMINING IMPACT OF TRAINING LOAD ON FITNESS AND INJURY
Pollock et al. (7) examined the impact of aerobic exercise frequency and duration on improvement in cardiorespiratory fitness (maximal oxygen consumption, V˙O2max) and injury rate during a 20-week jogging program. Subjects were assigned to 1 of 6 groups, including 15, 30, or 45 minutes on 3 days per week or 30 minutes per session on 1, 3, or 5 days per week. The training overload did improve aerobic fitness in direct relation to the frequency and duration of training (i.e., V˙O2max improvements were greatest for those exercising 45 minutes on 3 days per week and 30 minutes on 5 days per week). However, the injury rates also were the highest for these two groups (54% for those exercising 45 minutes per session and 39% incidence rate for those exercising 5 days per week). These results underscore the need for overload to generate improvements (reflected by the greater increases for those exercising more frequently or for longer duration) but highlight the dilemma of potential of injury with higher training levels.
Unlike acute injuries, overuse injuries result when the intensity of exercise is maintained at a high level for an extended period without adequate rest. The right amount of training must be individualized, taking into account overall training load and other variables, including nutrition and rest.
Incidence of injury is influenced by many factors, including one’s current fitness status, training level, biomechanics, and training techniques (2). Consider the increased risk of injury for an individual with a low fitness level who attempts an activity with improper form at an excessively high intensity. Some risk factors are intrinsic, including prior injury history, joint or bone alignment issues, body composition, and inadequate fitness. Other risk factors are extrinsic, including training errors (e.g.. excessive distances, fast progression, poor technique), environmental conditions (e.g.. heat/cold, humidity, altitude, wind, lighting), faulty equipment, and the surface on which the activity takes place. To lower the risk of injury, focus on aspects that can be modified (e.g.. having correct footwear, seeking correct instruction on technique, applying gradual progression) (2).
Finding the right exercise prescription is key to improving fitness and performance ultimately (1). However, when overload is excessive, performance can be jeopardized, with the potential for overtraining syndrome (OTS). A joint consensus statement by the European College of Sports Medicine and ACSM provides a comprehensive overview of prevention, diagnosis, and treatment of OTS (6).
The statement provides definitions for the commonly used terminology of overreaching and overtraining (see Box 2). The difference between the two terms centers on the time required for performance to be restored rather than a particular training stress or level of impairment (6).
Overreaching (6): “an accumulation of training and/or nontraining stress resulting in short-term decrement in performance capacity with or without related physiological and psychological signs and symptoms of maladaptation in which restoration of performance capacity may take from several days to several weeks.”
Overtraining (6): “an accumulation of training and/or nontraining stress resulting in long-term decrement in performance capacity with or without related physiological and psychological signs and symptoms of maladaptation in which restoration of performance capacity may take several weeks or months.”
Acute fatigue after overload in training is to be expected. Training cycles typically include periods of overreaching during which time the training level is elevated and an individual may experience a performance decrement. Such periods of intense training are required for future enhanced performance. “Functional overreaching” is possible with appropriate time for recovery (6). The key to functional overreaching is a short-term overload balanced by sufficient recovery. However, if intense training continues, moving into “nonfunctional overreaching,” the individual will have decreases in performance that last for several weeks or even months (6). OTS may result and is characterized by a decrease in performance and disturbed mood state (i.e., increased fatigue, decreased vigor) (6). A simple visual summary of progression from training to OTS is found in Box 3. Nonfunctional overreaching and OTS have common characteristics, and OTS is diagnosed only after other potential causes for performance and mood changes are ruled out (6) (see Box 4).
Finding the right exercise prescription is key to improving fitness and performance ultimately However, when overload is excessive, performance can be jeopardized, with the potential for overtraining syndrome (OTS).
PROGRESSION FROM TRAINING TO OVERTRAINING SYNDROME*
*Adapted from Meeusen R., et al. Prevention, diagnosis, and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sports Medicine and the American College of Sports Medicine. Medicine & Science in Sports & Exercise 2013;45(1):186–205.
ETIOLOGY OF OVERTRAINING SYNDROME
Diagnosis of OTS is a challenge because of the lack of a diagnostic test. Various factors must be excluded, including diseases or infections, negative caloric balance, insufficient carbohydrate or protein intake, iron or magnesium deficiencies, and allergies (6). Other factors may contribute, including training load to recovery imbalance, training monotony, number of competitions, personal problems, and work-related issues as well as sleep disturbances, exposure to altitude, and heat stress (6). Although these and other potential contributing factors should be considered, no causative mechanism has been identified, leading to a proposed labeling of OTS as “unexplained underperformance syndrome” (6).
The goal is to create a training program that provides sufficient, but not excessive, overload. For example, in one study examining changes that occur as athletes move from acute fatigue to overreaching, researchers followed 8 cyclists during 2 weeks of normal training, 2 weeks of intensified training, and 2 weeks of recovery training (5). Performance decreased almost immediately in the intensified training period and was attributed to acute fatigue. As the training continued, fatigue, mood disturbances, and perception of effort increased while performance decreased, as did maximal heart rate. A state of overreaching developed after 1 week of intensified training (5). The results of this study reflect the challenge of creating a successful training program.
Much of the research related to overtraining/overreaching has focused on endurance training. Resistance training of high volumes or intensities tends to maintain maximum muscular strength, although high speed and power may be decreased (6). Keep in mind that the additive stress of sport-specific training that potentially occurs in addition to resistance training may play a role in overtraining or overreaching. As with endurance training, adequate recovery is key (6).
Assessment of overtraining is difficult because an effective marker for OTS must be able to distinguish between acute changes versus chronic changes and also be predictive (i.e., changes in the marker should occur before the development of OTS) (6). In addition, to be feasible within a training situation, a marker must be easy to measure, not too invasive or expensive, and should not interfere with the training process (6). The Joint Consensus Statement reviewed many potential markers but concludes that none of the currently available markers meet these criteria (6).
Given the lack of evidence for treatment options (other than rest and very light training), prevention of nonfunctional overreaching and OTS is emphasized by the Joint Consensus Statement (6). Prevention centers on appropriate periodization and inclusion of needed recovery time within the training program (6). Aspects to consider include one passive rest day each week, ensuring adequate sleep (i.e., amount of sleep that allows the individual to feel wakeful during the day), and increasing fluid, carbohydrate, and energy intake to meet training demands (6). Recommendations for coaches and trainers include keeping accurate records of performance during training and competition (and adjusting training load as needed), avoiding training monotony, individualizing training, encouraging good nutrition and sleep, maintaining communication regarding physical and emotional concerns, and allowing for recovery after illness or injury (6).
Creating a well-balanced training program requires application of sufficient overload along with adequate recovery and rest. Individuals may find value in using a training log in which exercise activities are recorded as well as subjective aspects such as fatigue, muscle soreness, and perception of effort. Avoiding injury and OTS requires careful reflection on an individualized exercise program and a willingness to modify training as needed.
• Consensus Statement: Prevention, Diagnosis, and Treatment of the Overtraining Syndrome: Joint Consensus Statement of the European College of Sport Science and the American College of Sports Medicine. Available from: http://journals.lww.com/acsm-msse/Fulltext/2013/01000/Prevention,_Diagnosis,_and_Treatment_of_the.27.aspx.
• Extreme conditioning programs. ACSM brochure available from: http://acsm.org/docs/default-source/brochures/extreme-conditioning-programs.pdf?sfvrsn=4.
• Overtraining with resistance exercise. ACSM Current Comment available from: http://acsm.org/docs/current-comments/overtrainwithresistance.pdf?sfvrsn=4.
• Sprains, strains, and tears. ACSM brochure available from: http://acsm.org/docs/brochures/sprains-strains-and-tears.pdf?sfvrsn=2.
• Staying safe. Go4Life from National Institute on Aging available from: https://go4life.nia.nih.gov/stay-safe.