Subjective Load: Understanding Perceived Effort in Training

What is Subjective Load?

Subjective load refers to an individual's internal perception of the effort and physiological stress experienced during a physical activity or training session, serving as a crucial complement to objective measures of training intensity.

Understanding Training Load

In exercise science, "training load" encompasses the total physiological and psychological stress imposed on the body by exercise. It's a critical concept for optimizing performance, preventing overtraining, and ensuring effective progression. Training load is typically broken down into two primary components:

• Objective Load: This refers to quantifiable, external measures of work performed. Examples include the weight lifted (e.g., kilograms or pounds), repetitions performed, sets completed, distance covered (e.g., meters or miles), speed, power output (e.g., watts), and heart rate data. These metrics are externally verifiable and do not depend on the individual's perception.
• Subjective Load: This is the individual's internal interpretation of the difficulty, effort, and fatigue associated with the objective load. It accounts for personal factors that objective measures alone cannot capture, such as sleep quality, stress levels, nutritional status, and recovery.

Defining Subjective Load

Subjective load is the "feeling" of the workout. While two individuals might lift the same weight for the same number of repetitions, their subjective experience of that effort can vary widely based on their current physical and mental state, training history, and individual physiological responses.

The most common ways to quantify subjective load involve scales that allow an individual to rate their perceived exertion or how many more repetitions they could have performed. These methods provide valuable insight into the internal response to an external stimulus.

Common Measures of Subjective Load

Several validated tools are used to assess subjective load, each offering a slightly different perspective:

• Rating of Perceived Exertion (RPE): RPE is a psychophysical scale used to measure the intensity of exercise based on how hard you feel your body is working. It considers various factors, including heart rate, breathing, muscle fatigue, and sweating.

  • Borg Scale (6-20): This traditional scale, developed by Gunnar Borg, ranges from 6 (no exertion) to 20 (maximal exertion). The numbers are often correlated with heart rate (e.g., an RPE of 12-13 corresponds to roughly 120-130 bpm).
  • OMNI Scale (0-10) or CR10 Scale: These simplified scales range from 0 (no effort) to 10 (maximal effort). They are often preferred for their ease of use and direct interpretation, where a 7-8 might indicate a "hard" effort.
  • Session RPE (sRPE): This method extends the RPE concept to an entire training session. After a workout, the individual rates the overall perceived exertion for the entire session, which is then often multiplied by the session duration (e.g., sRPE x duration in minutes) to derive a cumulative training load score (e.g., Foster's TRIMP).

• Repetitions in Reserve (RIR): RIR is a subjective measure primarily used in resistance training to gauge the proximity to muscular failure. Instead of rating overall effort, an individual estimates how many more repetitions they could have performed with good form at the end of a set.

  • RIR 0: No more repetitions could be performed (training to failure).
  • RIR 1: One more repetition could have been performed.
  • RIR 2: Two more repetitions could have been performed.
  • And so on. RIR is highly effective for autoregulation, allowing lifters to adjust their training intensity daily based on how they feel, ensuring they are always training within a desired effort range relative to their current capacity.

The Importance of Subjective Load Monitoring

Integrating subjective load monitoring into training practices offers numerous benefits for athletes, clients, and trainers:

• Individualization of Training: Objective loads are universal, but subjective responses are personal. Monitoring subjective load allows for truly individualized programming that adapts to an individual's unique daily fluctuations in recovery and readiness.
• Fatigue Management and Overtraining Prevention: A sudden increase in subjective load for a given objective load can signal accumulating fatigue or inadequate recovery, indicating a need to reduce intensity or volume to prevent overreaching or overtraining syndrome.
• Program Adjustment and Periodization: Subjective data helps inform real-time adjustments to training plans. If a planned "moderate" session feels "very hard," it might indicate a need for a deload or a shift in subsequent sessions. It helps ensure the athlete is training in the correct "zone" for their periodization phase.
• Enhanced Client Communication and Autonomy: Teaching clients to use RPE or RIR empowers them to take ownership of their training and communicate their experience more effectively. It fosters a deeper understanding of their body's responses.
• Improved Exercise Adherence: By allowing for daily adjustments based on how an individual feels, subjective load monitoring can make training more sustainable and enjoyable, reducing the risk of burnout or injury.

How to Effectively Use Subjective Load

To maximize the utility of subjective load metrics:

• Consistent Application: Use the chosen scale consistently (e.g., always use the 0-10 RPE scale, or always apply RIR to your sets).
• Education and Practice: For RPE, explain what each number means and encourage individuals to practice rating their effort across various intensities. For RIR, ensure they understand how to accurately estimate remaining repetitions.
• Combine with Objective Data: Subjective load should not replace objective measures but complement them. Analyze the relationship between the two (e.g., "Why did 100kg feel like an 8 RPE today, when it usually feels like a 7?").
• Post-Session Reflection: Encourage individuals to reflect on their subjective experience immediately after a set or session, as recall can fade quickly.
• Track Trends: Look for patterns over time. A consistent increase in subjective load for the same objective work may indicate a need for a recovery week.

Limitations and Considerations

While invaluable, subjective load measures do have limitations:

• Inherently Subjective: The primary strength is also its weakness; it relies on individual perception, which can be influenced by mood, motivation, pain, or even desire to impress.
• Experience Level: Novice exercisers may struggle to accurately rate their RPE or estimate RIR due to a lack of experience with maximal effort or understanding of their body's limits.
• Contextual Factors: External factors like a noisy gym, a bad day at work, or an argument can influence perceived effort, even if physiological stress is unchanged.
• Lack of Direct Physiological Measurement: Subjective load does not directly measure physiological variables like heart rate, lactate, or oxygen consumption, which are crucial for certain research or high-performance applications.

Conclusion

Subjective load is a powerful, practical, and highly adaptable tool in the arsenal of any serious fitness enthusiast, athlete, or coach. By providing a window into the internal experience of training, it allows for a more nuanced, individualized, and responsive approach to programming. When combined with objective measures, subjective load monitoring facilitates smarter training decisions, optimizes adaptation, and ultimately helps individuals achieve their fitness goals more effectively and sustainably while minimizing the risk of overtraining and injury. Embracing subjective load means truly listening to your body and adjusting your training accordingly.