## 1 Introduction  
Exercise intensity refers to the amount of force exerted during an action and the degree of tension in the body. It is one of the main factors that determines exercise load and has a great stimulating effect on the human body. There are positive dose-response health/fitness benefits that result from increasing exercise intensity [1]. Appropriate exercise intensity can effectively promote bodily functions, thereby enhancing physical fitness. If the intensity of exercise is too high, it will reduce bodily functions and even cause sports injuries. Determining the exercise intensity is key to obtaining exercise benefits (improvement of cardiorespiratory fitness (CRF), muscular strength and endurance, flexibility, body composition, neuromotor fitness, etc.) and is one of the core steps in generating personalized exercise prescriptions [2]. There are many effective exercise intensity calculation methods that can be used to formulate personalized exercise prescriptions [1]. Absolute methods (oxygen uptake (VO2), metabolic equivalent of energy (METs), etc. ), relative methods (heart rate reserve (%FIRR), maximal heart rate (%HRmax), maximal oxygen uptake (%VO2 max), etc. ), and actual energy expenditure (EE) are commonly used. Although the absolute method can easily provide the exercise items necessary for achieving the target intensity (such as a comparison table of physical activity intensity [3; 4]), it does not consider an individual's CRF level, age, physiology differences, health status, living habits, or other personal factors. Thus, when estimating exercise intensity, the result may be too high or too low [5; 6], leading to misclassification of exercise intensity [7; 8; 9], and the recommended exercise is unreasonable. Therefore, it is more often recommended to use relative methods to formulate exercise prescriptions under the guidelines issued by the American College of Sports Medicine [9; 10], but the relative methods also have shortcomings. Relative methods do not directly give the specific exercise to achieve the target intensity but indirectly express the exercise intensity through other indicators. Among them, the commonly used %HRR method, the oxygen uptake reserve (VO2R) method, the %HRmax method, and the %VO2 max method obtain exercise intensity in terms of target heart rate (THR) and target VO2R, but the exercise wastage (amount of exercise) required by different individuals to reach a specific THR or target VO2R is different, which is affected by multiple factors such as gender, height, and weight. Exercise prescriptions are used to guide the public to exercise. For most ordinary exercisers who perform exercise prescriptions, their exercise knowledge is relatively limited, or they do not have with smart wearable devices. Prescriptions for these types of persons that define intensity only in terms of THR or target VO2R for exercise often result in the exerciser having difficulty understanding the meaning of the prescription and then performing it with an inappropriate intensity. Users will still encounter these problems when using exercise prescriptions for the first time, even if they have the knowledge and devices. In the current Chinese society, sports equipment has become popular, especially indoor electronic sports equipment. Not only do many communities provide free sports equipment for residents to use, but also, each family spends more on purchasing such equipment. Compared to traditional sports such as running and dancing, the use of sports equipment is more controllable because of the fewer external factors (such as running road conditions and dancing types). Therefore, the manner in which to combine sports equipment to accurately achieve target exercise intensity has become more important. This study used a linear regression model to find the relationship between heart rate and exercise wattage (because we changed the exercise load by adjusting the setting parameters (wattage) of the equipment) and describes the relationship with the slope S of the model's graph.