What is the ruling on studying physical fitness curricula that contain pictures of semi-naked women, and which cannot be studied without looking at these pictures?

Looking at pictures of immodestly dressed women is a gateway to tribulation and evil, so you must avoid it. Seek an alternative with pictures of men, or delete the pictures of women, and benefit from the scientific content without looking at them. If this is not possible, then avert your gaze whenever it falls upon a picture. Whoever fears Allah, He will make for him a way out, and whoever leaves something for the sake of Allah, Allah will compensate him with something better. Fear Allah as much as you can, and be keen to lower your gaze in compliance with His (the Most High) saying: "Tell the believing men to reduce [some] of their vision and guard their private parts." This is due to the great corruptions that result from letting the gaze wander, such as the darkening and corruption of the heart.