During warming up, muscle temperature increases. When muscles heat up, their tissues become more pliable and stretch more easily because enzymes work faster, blood flow rises, and the muscle-tendon unit becomes less stiff. This improved elasticity supports a greater range of motion and lowers injury risk. So the expected outcome is higher muscle temperature with greater elasticity. If temperature dropped or stayed the same, or elasticity decreased, that would not align with the warming-up effect.

RPE is a subjective way to measure how hard you feel your body is working during exercise, and it’s used to tune intensity to the person in front of you. In exercise prescription, you’ll have the client rate their effort on a scale (such as 0–10 or 6–20) while they exercise, and you adjust pace, resistance, or duration to keep the workout within a target effort range. This allows you to set and modify intensity without relying on exact heart-rate numbers or VO2 measurements. Using RPE helps because effort can vary day to day due to fatigue, temperature, hydration, or caffeine, and some people respond differently to the same workload. For example, you might aim for a moderate range around 12–14 on the 6–20 scale (roughly corresponding to comfortable but challenging work) or around 5–6 on a 0–10 scale. For intervals, you’d push into higher ranges (like 15–18) and drop back for recovery. RPE is especially useful when heart rate is unreliable (medications, heat, or deconditioning) and for fostering autoregulation, where the client adjusts effort to how they feel in the moment.

Heart rate is the number of times the heart beats in one minute. It’s a rate, shown in beats per minute, that tells you how often the heart is contracting. It can rise with exercise, stress, or excitement, and it falls with rest or improved fitness. The other ideas describe different things: a single beat during rest is just one beat, not how often it happens; the speed of blood flow through arteries refers to how fast blood moves (velocity); and the force of heart contractions refers to how hard the heart squeezes each beat (contractility). So the best description is the count of heartbeats per minute.

Being physically inactive is a common risk factor for heart disease. When you live a sedentary life, your blood pressure, cholesterol, and blood sugar regulation can worsen, and weight can increase, all of which raise cardiovascular risk. Regular exercise counters these issues by strengthening the heart, improving lipid profiles, lowering blood pressure, aiding weight management, and improving insulin sensitivity. So the risk factor exercise helps mitigate is a sedentary lifestyle. An active lifestyle lowers risk, high hydration status isn’t a typical heart disease risk factor, and regular endurance training is a protective behavior rather than a risk factor to address.