This article was provided by Training and Conditioning
By: Ryan Curtis MS, ATC, CSCS, Associate Director of Athlete Performance and Safety, Korey Stringer Institute
Athlete monitoring is becoming standard practice for maximizing player performance,reducing injury risk, and optimizing competition readiness. For high-performance programs, monitoring load-performance and load-injury relationships are essential for providing insight into how athletes are responding to stresses incurred during and outside of training and competition. Ultimately, how an athlete performs is impacted by the accumulation of stress and the efficacy of training. Therefore, it is important to evaluate stress imposed during training and match sessions, as well as, the strain incurred by each athlete. Understanding the difference between stressors (i.e., intense exercise, heat, cold, altitude, etc) and the strain (body’s response to stress) experienced by a biological system (i.e., human body) is essential to monitoring and manipulating parameters important for athlete preparation. Other benefits to monitoring athletes beyond determining training efficacy, such as gathering scientific explanations for changes in performance or injury risk, enhancing coach and practitioner confidence when manipulating training loads, and boosting athlete-coach- practitioner relationships all contribute to the efficacy and buy-in of monitoring practices. There are four main purposes for monitoring athletes; optimizing readiness, ensuring proper prescription of stress and recovery (periodization), reducing injury risk, and monitoring safe and effective return to play programs (Figure 1). While each of these purposes are important, emphasis and priority placed on these purposes will vary based on team’s load monitoring philosophy.
Monitoring Training and Competition Load
When monitoring the dosage of stress imposed during training or competition, practitioners and scientists typically refer to training load. Load is simply the product of duration and intensity of activity. Training load can be further described as either external (work imposed independent of internal strain) or internal (response of the body to external load), as shown in Figure 2. The association between external and internal load can give great insight into the status of the athlete (i.e., fresh vs. fatigued). With advancements in wearable technology, monitoring of athletes’ external load has received a great deal of attention. Specifically, global positioning systems (GPS) capabilities have allowed ease of monitoring parameters such as distance, time, and efforts in multiple velocity zones (0-7.2 km/h-walk, 7.2-14.4 km/h-jog, 14.4-21.6 km/h-run, >21.6 km/h-sprint) used for tracking running performance. GPS-enabled devices use positional differentiation to calculate distance and acceleration.
Beyond quantifying the intensity distribution of session types (i.e., match, training, conditioning, etc.), GPS metrics are often reported as aggregate measures such as high-intensity running distance (distance >14.4 km/h), number of sprints (efforts > 25.2 km/h), and average speed (meters per minute). However, GPS technology is limited in its ability to detect external movement beyond positional change and additionally, has serious limitations with tracking movement indoors. This leaves monitoring of indoor team sports such as basketball and volleyball at a disadvantage. However, modern player tracking technology typically uses integrated inertial sensors such as accelerometers, gyroscopes, and magnetometers to help quantify stress imposed in all three planes. Calculated metrics such as PlayerLoad TM (Catapult) from integrated inertial sensors have a strong relationship with running performance measures such as total distance covered, while additionally estimating general load on the body and therefore stress from actions such as tackling, accelerations, decelerations, changes of direction and collisions. Due to the inertial movement sensors ability to detect magnitude of movement (i.e., g-forces) in 3 planes of motion, a single arbitrary unit of load might give a more accurate display of total stresses incurred during activity.
Both physiological and psychological measures such as heart rate, lactate, muscle oxygen, and rating of perceived exertion (RPE) can be used to monitor loads sustained internally. Of the numerous methods of objectively quantifying internal load, heart rate derivatives such as time in heart rate zones, expressed as percent of maximum heart rate, and weighted scores such as training impulse (TRIMP) are most commonly used. These measures allow categorization of training stress into relative zones such as high, moderate, and low. Of the methods to quantify internal load by subjective means, using RPE and session RPE (sRPE) are by far the most common. sRPE is simply the product of session duration and the athlete-reported RPE post-training/competition. This subjective measure has shown good association with external running performance measures.
Monitoring Readiness, Recovery and Wellness
Monitoring readiness, recovery, and wellness requires both physiological and psychological assessment in order to gain understanding of an athlete’s true state. These assessments could be as simple as asking the athlete “how do you feel?” or as complex as using microtechnology (telemetry or photoplesthsmography) to ascertain the variability in heart beat to beat intervals during rest or sleep. Monitoring the response to training and/or competition gives the practitioner great insight into individual dose-response relationships and helps to promote precision with recovery practices. For example, if an athlete is excessively fatigued, coaches may prescribe a recovery session or reduce training load for that day. Current practices in monitoring athlete readiness prior to activity include heart rate-based autonomic nervous system assessment (i.e., heart rate variability, HRV; heart rate recovery, HRR), neuromuscular function tests (i.e., counter movement jump, CMJ; reaction tests), and wellness questionnaires/assessments (i.e., stress, fatigue, soreness, anxiety). More extensive monitoring such as biochemical/immunological/hormonal assessment (i.e., blood, saliva, and urine-biomarkers) and psychological inventories (i.e., Profile of Mood States, Sport Anxiety Scale, Rest and Recovery Questionnaire) can give insight into overtraining or maladaptation if assessed longitudinally.
Limitations in Athlete Monitoring
While there is much to gain from monitoring athletes, there are several limitations that must be considered when implementing a monitoring program. Monitoring athletes does not always require large funding sources (i.e. subjective markers of training load combined with wellness reporting), however analyzing data does require time, manpower, and experience/skill. With vast amounts of data pouring in from sometimes multiple technologies and questionnaires, persons experienced in data management and analysis are often needed derive meaning and interpretation beyond simple descriptive reporting. In addition, attaining buy-in from athletes and coaching staff is sometimes difficult if immediate returns are not seen. Regarding technological limitations, very little validation and reliability testing is conducted by parties outside of the technology manufacturer. With that, the way in which raw data is processed and filtered varies by manufacturer and software version. Because software updates can occur quite often and the way in which data is filtered and reported is changed, validity and reliability of the device will change concurrently. This has severe implications when determining the precision and consistency of measurement longitudinally.
Taken together, programs must weigh the benefits and limitations of athlete monitoring together. Without structure in data management, plans for implementation based on data analysis, and athlete-coach buy-in, monitoring athletes can be a waste of time and resources that could be used to gain advantage elsewhere. However, if care is taken in promoting, structuring, and implementing a purposeful and practical monitoring program, teams stand to gain a great advantage in maximizing the health and performance of their athletes.