If you’re beginning a new fitness routine or trying to take your current one to the next level, it’s completely normal to wonder: “How hard should I work out?”
This question is more nuanced than it seems. There isn’t a perfect answer that applies to everyone. Workout intensity depends on your experience level, your goals, your health history, and even how you’re feeling on a particular day. Instead of thinking of intensity as a single number, it’s more helpful to view it as a dial. It’s something that you adjust up or down depending on what your body needs.
Finding the right training intensity is both an art and a science, and striking that balance is essential for progress, injury prevention, and long-term consistency. Push too hard, and you risk burnout or injury. Don’t push enough, and you may struggle to see meaningful results. The key is learning how to read and respond to your body’s signals.
In this guide, we break down what exercise intensity really means, how to measure it, what national guidelines recommend, and how factors like injury, pain, and recovery influence how hard you should train.
Understanding Exercise Intensity
Exercise intensity describes the amount of effort you’re putting into your workout, and it can be measured in several ways. Some people prefer scientific tools like heart rate monitoring. Others may rely on the Rate of Perceived Exertion (RPE), which reflects how hard the workout feels on a scale from easy to extremely challenging.
For strength training, one of the most practical tools is the concept of Repetitions in Reserve (RIR). RIR simply estimates how many repetitions you could perform after completing a set. If you finish 10 push-ups and feel confident you could have performed two more, you’re working at about 2 RIR.
Lower RIR values (zero to one) reflect near-maximal effort and demand a high level of recovery. A range of one to two RIR is typically ideal for strength gains, offering enough training stimulus without unnecessary strain. Higher RIR levels, three or more, indicate a lighter workload, which may be appropriate for endurance sessions, warm-ups, beginners, or days when your energy or recovery is low. This flexibility makes RIR a useful guide for adjusting intensity based on how your body feels that day.
National Exercise Guidelines
While individual training intensity should always be personalized, national organizations like the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) provide helpful baselines. For general health, adults are encouraged to accumulate at least 150 minutes of moderate aerobic activity per week. This includes activities such as brisk walking or cycling, or 75 minutes of vigorous activity like running.
Strength training is also essential and should be performed at least twice a week, targeting all major muscle groups to support muscle mass, bone density, and overall mobility. Additionally, incorporating regular stretching and balance work is strongly recommended, especially for older adults, to enhance coordination and support joint health. These guidelines offer a broad structure, but the ideal training intensity within them will still depend on your body’s needs and daily readiness.
Training While Injured or in Pain
One major factor that influences workout intensity is tissue irritability, a term physical therapists use to describe how sensitive a tissue (muscle, tendon, joint, etc.) is to load, movement, or activity. If you’re struggling with discomfort, your level of tissue irritability can guide your intensity choices.
- Listen to Your Body
Not all pain means “stop,” but persistent or sharp pain is a sign something needs to be modified. Distinguishing soreness (normal after exercise) from true pain (signal of overload) helps prevent setbacks.
- Adjust Your RIR on Painful Days
If something feels irritated:
- Increase your RIR
- Choose lighter loads
- Slow down your reps
- Prioritize form and control
This allows you to maintain training stimulus without stressing sensitive tissues.
- Incorporate Active Recovery
Activities such as walking, gentle cycling, mobility work, or swimming help increase blood flow and reduce stiffness without overloading the body.
- Consult a Physical Therapist When Pain Persists
A physical therapist can identify underlying issues such as mobility restrictions, muscular imbalances, or improper movement patterns. From that, build a program that keeps you active while you heal.
How to Find Your Ideal Workout Intensity
Striking the right balance between challenging yourself and giving your body time to recover is essential for long-term progress. If you’re just starting out, the best approach is to begin with moderate intensity and build gradually; your body adapts quickly, and giving it time to adjust helps prevent the discouragement that often comes with doing too much too soon.
Tracking how your workouts feel, especially noting your RIR, energy levels, and any discomfort, can help you identify when it’s appropriate to increase the intensity or when a lighter day may be more beneficial. Recovery practices, such as getting adequate sleep, staying hydrated, and fueling your body with nutrient-rich foods, play just as important a role as training itself. When your recovery habits are consistent, your body becomes more resilient and better able to adapt to increasing demands. Over time, you’ll develop an intuitive sense of how hard you should work out on any given day, making your fitness journey more sustainable and enjoyable.
Building a Sustainable Relationship With Exercise
A sustainable fitness routine isn’t built on pushing yourself to your limits every single day. It’s built on understanding what your body needs and developing a healthy, flexible relationship with movement. Instead of viewing exercise as something that requires constant intensity, it’s helpful to think of it as a long-term partnership with your body. Some days you’ll feel energetic and capable of challenging workouts; other days you’ll benefit more from lighter movement or focused recovery. Both types of days are valuable, and both contribute to your progress.
The goal is to finish most workouts with a sense of accomplishment rather than exhaustion. You should feel energized, more confident in your abilities, and motivated to continue, not worn down or discouraged. If you regularly find yourself overly fatigued or mentally drained afterward, it may be a sign that your training needs to be adjusted or that recovery isn’t keeping pace with your workload.
Sustainability also comes from consistency, and consistency thrives when exercise feels purposeful and enjoyable rather than punishing. This means choosing activities you like, setting realistic goals, and celebrating small wins along the way. When the focus shifts from “how hard can I push today?” to “how can I support my progress today?” your training becomes more adaptable and empowering. Over time, you’ll build trust in your body’s signals, confidence in your capabilities, and a rhythm of movement that aligns with your lifestyle.
Working with a physical therapist or movement professional can make this process even more effective. They can help identify imbalances, refine your form, and design programs that match your goals while respecting your body’s limits. With guidance and mindful progression, exercise becomes not just a method for building strength. but a meaningful, enjoyable part of your daily life.
Your Ideal Intensity Is Personal
Your ideal workout intensity isn’t defined by a number, a trend, or someone else’s routine. It’s determined by your goals, your recovery, your body’s feedback, and your life circumstances. By using tools like RIR, paying attention to tissue irritability, and following evidence-based guidelines, you can train smarter, not just harder, and build a fitness routine that supports long-term health and enjoyment.
Challenge yourself when it serves you. Ease up when your body asks for it. Stay consistent, stay curious, and let your own progress guide the way.
Not sure where to start or need assistance recovering? If so, Therapy Excellence Physical Therapy can help. Contact us today to get started.
