Cranium describes the part of the skeleton that protects the brain. It is the upper part of the skull formed by several bones that fuse together to create a protective case around the brain. The jawbone is not part of the cranium, being part of the facial skeleton instead. The spine, ribcage, and pelvis are separate skeletal structures and do not enclose the brain. So cranium refers to the skull.

Specific goals give you a clear target to work toward. When a goal is precise about exactly what you want to achieve, you can break it down into concrete steps, choose the right practice activities, and plan your training to reach that exact outcome. It also makes it easy to know when you’ve hit the target, so progress can be measured and kept motivating. That’s why the statement about being as specific as possible regarding what you want to achieve is the best choice. If goals are vague, you’re unsure what to improve or practice. If they’re unmeasurable, you can’t tell whether you’ve improved. If goals are the same for everyone, they don’t account for individual starting points or needs. And aiming for something that’s unmeasurable or too flexible makes it hard to focus and track progress.

In IPM, Output is the actual motor action produced by the performer—the movement that happens once the brain has made a decision. It’s the observable physical response, like the kicking motion in football or the swing of a bat, driven by the brain sending commands to the muscles. Think of it as the transition from thought to action: sensing the situation (input), processing that information (deciding what to do), and then carrying out the chosen action (output). The other ideas in the options relate to other stages: data processed by the brain describes input and processing, the evaluation of performance is feedback after the action, and the memory of past performances relates to memory or retrieval.

Low-intensity exercise relies on aerobic metabolism because the body can deliver enough oxygen to the working muscles to meet the energy demand. In the aerobic system, glucose and fats are broken down in the mitochondria using oxygen to produce ATP, which can fuel activity for longer periods without quickly causing fatigue. While this system works slower than the immediate energy you get from the ATP-PC system, it lasts much longer, making it ideal for sustained, easy to moderate efforts. The ATP-PC system provides energy for very short, explosive bursts (about up to 10 seconds) and the anaerobic/lactic system becomes important at higher intensities when oxygen delivery can’t keep up, producing lactate. Oxygen debt is about the extra oxygen needed after exercise to recover, not the energy source during the activity. So, for low-intensity work, the aerobic system is the main supplier of energy.