The correct answer is B. A combination of basic level training and HIIT is needed to improve endurance.
“The radical change of speed in HIIT (high-intensity interval training) is specifically designed to ‘stress’ the body, which responds by adapting and getting stronger. But anyone who replaces basic level training entirely with HIIT runs the risk of overexertion, weakening the immune system and even worsening performance. It’s like building a house: you can only build a roof once the foundations are in place. In sport, basic level training is the foundation. However, running at only a basic level, never pushing out of your comfort zone, will keep you fit but won’t improve your performance. A combination of basic level training and HIIT is essential for improving endurance.
If you don’t exercise regularly, you must start with basic level training to strengthen your endurance first. For example, you could jog for half an hour at a pulse rate of just under 100 beats a minute. Once you’ve built a solid foundation, you can start adding HIIT. Start with short intervals of between 15 and 30 seconds at a higher pulse rate. You can gradually extend the intervals.
Beginners or elderly people should consult a doctor before starting HIIT as their cardiovascular systems are not used to high performance peaks. A cardiovascular check-up will determine what level of stress your body can withstand and find a healthy intensity level for you.”
Andreas Tasci, Master Personal Trainer