Q.Which method of endurance development alternates measured work periods (for example, repeated 400 m runs) with planned recovery periods?

The key phrase is "alternates measured work periods … with planned recovery periods." That is the exact signature of the interval method: you run a fixed distance (say 400 m) at a target pace, then rest for a set time (e.g. 90 seconds), then repeat. The work and rest are both prescribed in advance.

• (a) Continuous method — steady, uninterrupted effort (e.g. a 5 km jog). No alternating recovery periods. …

This question tests your understanding of the core methods used to develop endurance — a fundamental component of physical fitness. The key is to recognize what distinguishes each method by its structure of work and rest.

The interval method is built on the principle of alternating measured work bouts (e.g., running 400 m at a specific pace) with planned recovery intervals (e.g., walking or jogging for a set time). The recovery is not complete rest — it's active recovery, and the duration is carefully controlled so the athlete can repeat the work at the same intensity. This method is highly effective for improving both aerobic and anaerobic endurance because it pushes the heart rate up during work and allows it to partially recover during the rest period, training the cardiovascular system to adapt.

Now look at the other options and why they don't fit:

• (a) Continuous method: This involves sustained, uninterrupted activity at a steady pace (e.g., a 30-minute jog). There are no planned work/rest alternations — it's one continuous effort. So it's wrong here. …