How do you know if you're working hard enough?

I recently started a long-term client on a free weight-based strength training programme and having previously only done lighter, resistance band training with cardio elements, she saw her heart rate data (from a Fitbit/exercise tracker) and wondered out loud whether she had worked hard enough…

My client’s question/thought is a great question: how do you actually know if you’ve worked hard enough during a session? Anyone can perform an exercise, get out of breath or get tired and think they have worked hard enough, but how do you actually know if you’re pushing yourself properly?

Your training

The type of training you’re doing (and your goal) determines what metrics you should use to see how hard you’re training…

Fat-burning

When working with clients who are specifically focused on fat-burning, I track their heart rate (including time spent in specific heart rate zones) and calories burned during a session. The optimum fat-burning levels are when clients are training at 70-90% of their maximal heart rate. For example, when I do boxing workouts on the punchbag, I know I’m pushing myself when my heart rate reaches the 70-90% level.

Lean muscle development

Lean muscle is developed by performing exercises that break down the existing muscle fibre and (using proteins) repair and grow larger muscle fibres. (This is a very top-level summary of the highly complex process). 

The optimum rep range for muscle growth is 8-12 reps; if you can achieve 12 reps relatively comfortably on any given exercise you should increase the weight/resistance for your next session.

Strength / Flexibility training

Similar to growing muscle, you can tell if you’re working hard enough if you’re getting to the point where it is hard to perform the exercise with proper form. Strength and flexibility training can be very subjective so I use a client’s form and technique as a guide to their levels of fatigue. For example, after performing a number of static lunges, a client who is fatigued and reaching muscle failure will struggle to return to the ‘start’ position using incorrect form.

To generalise, if you’re struggling to finish the exercise with correct technique then you’re working hard enough :)