A strenuous activity or action involves a lot of energy or effort. 艰苦的; 剧烈的
adjective [原级] 费力的,艰苦的;积极的,坚决的
Avoid strenuous exercise in the evening. 应避免在傍晚进行剧烈的运动。
stren(=strength力量) + uous → 需要用力量的 → 费力的
Avoid strenuous exercise in the evening. 应避免在傍晚进行剧烈的运动。