Across today's professional sports worlds, managers prioritize data-driven decision making right alongside traditional training and coaching. Athlete monitoring sensors lead the forefront of this revolution. Sensors assist with injury prevention, recovery management, health assessment, performance evaluation and optimization.
This article explores the different types of sensors used in athlete monitoring devices that enable coaches, athletes and trainers to maximize an athlete's performance.
Accelerometers maximize performance and identify injuries
Nearly every type of motion sensor uses accelerometers. In sports, accelerometers are used in Inertial Monitoring Unit (IMU) devices to help quantify athletes' readiness, responsiveness, and fatigue. IMU devices can reveal discrete motion, providing biomechanical analysis in activities like running, cycling, swimming, or tracking steps.
For example, at the beginning of a running training session, an accelerometer can monitor a runner's stride and their control of their body throughout a single stride. An increase in inertial loads during a stride can indicate an athlete's fatigue levels during the run. Sophisticated software is combined with accelerometers to establish training models using athlete data and provide optimized training regimes.
Athlete monitoring accelerometers like the ADXL362 typically utilize kHz sampling rates to provide high accuracy data and operate on low power to maximize battery life.
Accelerometers are also placed inside helmets and headgear to detect high impacts and predict injury. In the National Football League (NFL), mouthguard systems use accelerometers to collect individual players' head kinematic data. This data reveals how fast and in what direction a player's head moves during impact, helping to detect concussions and monitor impact data over time. NFL engineers can also use this data to analyze the position-by-position impacts experienced and work with helmet manufacturers to make position-specific head protection to better defend against different types of impact.
GPS/GNSS track athlete speed and distance
While accelerometers track step count, GPS/GNSS motion sensors are the best way to track athlete travel distance and elevation. GPS and GNSS sensors are common activity trackers for professional and amateur sports, worn on the body or specialized gear. Popular activity trackers such as Garmin, Fitbit and Apple watches are worn on an athlete's wrist and utilize GPS/GNSS sensors to track athlete speed, distance covered and elevation.
Other devices, such as Garmin cycling devices, can be 'worn' on the handlebars of a bicycle to help the cyclist navigate, track their speed and provide performance monitoring insight using GPS sensors. By tracking speed, incline and distance, insights about the cyclist's endurance and power output help calculate optimal training load and real-time performance.
GPS and GNSS receivers that can operate on low power, such as TESEO-LIV3R, are common in athlete monitoring devices. Typically, GPS receivers are the most energy-hungry sensors in an athlete monitoring device.
Heart rate sensors
The heart rate monitoring sensor is perhaps the most important sensor to provide individualized performance statistics. Optical Heart Rate monitors are the most common heart rate monitors used in wearable athlete monitoring devices. Optical Heart Rate monitoring (HRM) — also known as Photoplethysmography (PPG) — is a complex technology that is now common in wristwatches and chest wearables.
Heart rate monitors monitor exercise intensity and can calculate heart rate intensity zones, heart rate variability, caloric expenditure, cardiac efficiency and overall training load. When paired with other sensor data such as distance, incline and speed, heart rate data can help determine overall training status and track athlete performance over time.
Professional soccer offers a popular example of this combination. Players wear a FIFA-approved STATSports heart rate monitor and GPS tracker during training and games. This data helps managers optimize training load and gameday player health by tracking individual athlete exercise intensity and overall team exertion. Optical HRM devices, such as the Si117x/8x series, can be worn on the skin surface and provide a noninvasive method of detecting a user's pulse.
Blood oxygen monitors and lactate sensors
Like a heart rate monitor, blood oxygen and lactate sensors can provide in-depth insights into an athlete's performance over time. This information is most valuable in endurance sports such as running and cycling, where athletes can exercise for several hours without pause.
Oxygen is critical for cellular respiration, which is how athletes fundamentally exercise at a cellular level. Monitoring blood oxygen saturation levels in athletes is essential for endurance athletes, especially those training at high altitudes where oxygen is less available. If an athlete's oxygen levels drop too low, blood lactate levels can increase, thereby lessening the effectiveness of their training or hindering competition performance.
Blood lactate sensors have historically required a blood sample via a finger prick. However, noninvasive wearable monitors that measure lactate levels in sweat are gaining popularity, despite uncertainty about correlations between lactate levels in sweat and in blood. An athlete's lactate threshold is the point at which lactate begins to accumulate in the blood, which is an indication of overexertion that reduces performance. To maximize training and performance, athletes can use continuous blood lactate monitors to optimize their training load. If they train too hard, they can decrease their load to exercise for longer.
Environmental sensors: temperature, humidity and altitude sensors
Environmental sensors are helpful for creating athlete performance models to adapt training programs. For example, training in hot and humid environments causes the body to divert oxygen from working muscles to help keep the body cool, reducing performance. In higher temperatures, some professional runners may decrease their pace by over 10% to compensate for the drop in muscular oxygen delivery. The same is true at higher elevations due to an overall decrease in oxygen availability.
However, athletes often train in the heat and at altitude intentionally to increase heat-shock proteins and produce more blood plasma volume, making it easier for the human body to keep exercising while purging heat more efficiently. This blood oxygen efficiency can be estimated via performance models when combined with performance tracking (such as speed and heart rate) and environmental data. For example, Garmin smartwatches track athletes' VO2 Max (oxygen use efficiency) and heat acclimation to help optimize their training and recovery load.
Temperature, humidity and pressure sensors such as the BME280 must be small and energy efficient to be suitable for portable, battery-powered devices. In some cases, such as the Garmin Fenix 6X Pro, the temperature sensor is likely integrated within the MCU, thereby reducing the footprint demand.
Sensors track the future of athletics
Advanced sensor technology in sports paves the way for teams' and individual athletes' success. Athlete monitoring sensors are invaluable tools that help prevent injury and increase performance. When paired with software, data and human knowledge, sensors provide a competitive advantage in nearly every sport.
